@- The Geologic Occurrence Of Monazitc GEOLOGICAL SURVEY PROFESSIONAL PAPER ‘ 530 MISBOvSK/ E 92 z”; ‘ 4&1 E NCE? LIBRARY The Geologic Occurrence Of Monazitc By WILLIAM C. OVERSTREET GEOLOGICAL SURVEY PROFESSIONAL PAPER 530 fl review of tfie distriéutim of monaziz‘e mm] of t/ze geologic controls affecting t/ze amount qf t/zorium in monazite UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967 UNITED STATES'DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library of Congress catalog-card No. GS 67-191 (Aa‘fi" 5L? '; [.HBPAaY For sale by the Superintendent of Documents, US. Government Printing Office Washington, DC. 20402 CONTENTS 39’? In Pa“ Monazite localities—Continued Page Abstract ........................................... 1 Asia ______________________________________ 53 Introduction ....................................... 3 Burma _____________________________________ 53 Purpose and scope of report ...................... 3 Ceylon_____‘ _______________________________ 53 Acknowledgments _______________________________ 3 Crystalline rocks ....................... 54 Description of monazite ......................... 4 Cons01idated sedimentary rocks .......... 55 Discovery, synonymy, and synthesis ---------- 4 Fluvial deposits ________________________ 56 Physical properties .......................... 4 Beach placers __________________________ 58 Optical properties ........................... 5 China, _____________________________________ 60 Crystallography ---------------------------- 5 Federation of Malaya ....................... 62 Composition _______________________________ 6 J ohore ________________________________ 63 Production and use ............................. 6 Kedah ________________________________ 63 Occurrence ......................................... 11 Kelantan ______________________________ 64 Cycles in crystalline rocks ....................... 12 Negri Sembilan _________________________ 64 Metamorphic cycle .......................... 16 Pahang ________________________________ 64 Magmatic cycle ____________________________ 20 Perak _________________________________ 66 Cycle in sedimentary rocks. ...................... 23 Selangor _______________________________ 67 Economic relations of the cycles .................. 25 Trengganu _____________________________ 67 Age relations ................................... 25 India ______________________________________ 67 Monazite localities .................................. 26 Crystalline rocks ________________________ 68 Africa ----------------------------------------- 26 Kerala, _____________________________ 68 Algeria .................................... 26 Mysore ____________________________ 68 Central African Republic ———————————————————— 26 Andhra Pradesh ____________________ 69 Ethiopia ................................... 27 Bihar _____________________________ 69 Federation of Rhodesia and Nyasaland ———————— 27 Rajasthan _________________________ 69 Crystalline rocks ........................ 27 Consolidated sedimentary rocks .......... 69 Fluvial deposits ———————————————————————— 29 Fluvial placers _________________________ 70 Lacustrine placers ...................... 30 Beach placers __________________________ 70 Ghana .................................... 30 Kerala ____________________________ 70 Kenya ..................................... 34 Gujarat ___________________________ 72 Liberia .................................... 34 Madras and Andhra Pradesh _________ 72 Malagasy Republic ......................... 34 Orissa _____________________________ 73 Crystalline rocks, eluvium, and fluvial sedi- Japan _____________________________________ 73 111811133 ------------------------------- 34 Inner zone of southwest Japan ........... 74 Littoral deposits ........................ 38 Kyfishfi ___________________________ 74 Mauritania ................................ 39 Honshu ___________________________ 74 Mozambique ------------------------------- 39 Outer zone of northeast Japan ............ 74 Nigeria ------------------------------------ 40 Honshfi ___________________________ 74 Republic Of Cameroon ----------------------- 42 Korea, _____________________________________ 75 Republic of Guinea ......................... 42 Cholla-namdo __________________________ 76 Republic of Senegal ......................... 43 Chblla-pukto ___________________________ 76 Republic of South Africa -------------------- 43 Ch’ungch’éng-namdo ___________________ 77 Cape of Good Hope Province ............ 43 Ch’ungch’éng-pukto ____________________ 78 Transvaal Province ..................... 43 Kybngsang-namdo and Kyongsang-pukto_- 78 Natal --------------------------------- 4-6 Kangwbn-do ___________________________ 78 Republic of the Congo (Léopoldville) --------- 47 Kybnggi-do and Hwanghae—do ........... 79 Ruanda—Urundi ---------------------------- 47 P’ybngan-namdo and P’yongan-pukto ..... 79 Sierra Leone ------------------------------- 48 Hamgybng—namdo and Hamgyong-pukto_- 80 Somali Republic ............................ 48 Pakistan __________________________________ 80 South-West Africa —————————————————————————— 4-8 Philippines ________________________________ 81 Swaziland Protectorate ...................... 49 Republic of Indonesia _______________________ 81 Tanganyika ................................ 50 Sarawak and North Borneo .................. 82 Uganda Protectorate ........................ 50 Sarawak ______________________________ 82 United Arab Republic _______________________ 51 North Borneo __________________________ 83 IV Monazite localities—Continued Asia—Continued Thailand .................................. Tibet _____________________________________ Australia, New Zealand, and Antarctica ........... Australia __________________________________ Northern Territory _____________________ Queensland and New South Wales ________ South Australia ________________________ Tasmania _____________________________ Victoria _____________________________ .- Western Australia ______________________ New Zealand ______________________________ South Island ___________________________ North Island ___________________________ Antarctica ____________ North America ____________ Cuba ................ Dominion of Canada--- British Columbia- - _____________________ Manitoba ----------------------------- Newfoundland_ _ - _ _____________________ Northwest Territories- ------------------ Nova Scotia --------------------------- Ontario ------------------------------- Quebec -------------------------------- Saskatchewan __________________________ Yukon Territory- - --------------------- Greenland --------------------------------- Honduras and British Honduras ------------ Mexico --------------- L -------------------- United States of America ____________________ Alabama --------- - -------------------- Alaska ------------------------------- ' Southeastern AEaska ---------------- South-central Alaska ---------------- East-central Alaska _________________ Northeastern Alaska ---------------- Central Alaska --------------------- Southwestern Alaska ---------------- West-central Alaska ----------------- Arizona ------------------------------- Arkansas ------------------------------ California ------------------------------ Crystalline rocks ------------------- Sandstone ------------------------- Stream deposits -------------------- Beach deposits --------------------- Colorado ------------------------------ Crystalline rocks ------------------- Fossil placers ---------------------- Present stream placers -------------- Connecticut ---------------------------- Pegmatite ------------------------- Other plutonic rocks ---------------- Sandstone ------------------------- Delaware ------------------------------ Florida -------------------------------- Inland deposits --------------------- Present beaches and dunes of the Atlantic coast -------------------- Present beaches and deltas of the gulf coast ---------------------------- CONTENTS Page 83 83 83 84 84 84 9 1 92 93 94 97 98 99 105 106 106 106 108 109 109 110 110 111 111 112 113 114 114 116 116 117 118 119 121 122 122 122 124 124 124 124 126 127 130 Monazite localities—Continued North America—Continued United States of America—Continued Georgia-- ----------------------------- Crystalline rocks ----------------- Stream sediments in the Piedmont and Blue Ridge provinces _____________ Unconsolidated sediments of the Coastal Plain province -------------------- Stream sediments in the Coastal Plain province ------------------------- Beaches of the Sea Islands ........... Idaho --------------------------------- Crystalline rocks ------------------- Replacement deposits and veins ------ Placers ---------------------------- Shoshone, Latah, Clearwater, and Nez Perce Counties ----------- Idaho County ------------------ Valley County ------------------ Adams, Payette, and Gem Coun- ties ------------------------- Boise County __________________ Ada, Owyhee, Elmore, and Custer Counties --------------------- Lemhi, Camas, and Blaine Coun- ties ------------------------- Lincoln, Minidoka, Bannock, and Bingham Counties ------------ Illinois -------------------------------- Hicks Dome primary monazite ------- Detrital sources -------------------- Indiana ________________________________ Iowa __________________________________ Kentucky and Missouri ------------------ Louisiana ------------------------------ Maine --------------------------------- Maryland ------------------------------ Massachusetts -------------------------- lVIichigan ------------------------------ Minnesota ----------------------------- Mississippi ----------------------------- Sedimentary rocks of Eocene age _____ Surficial, fluvial, and beach deposits"- Montana ------------------------------ Crystalline rocks ____________________ Fossil placers ----------------------- Present stream placers --------------- Nebraska ------------------------------ Nevada ________________________________ New Hampshire ------------------------ New Jersey ____________________________ New Mexico ___________________________ Crystalline rocks ____________________ Fossil placers _______________________ Fluvial and other surficial deposits--_- New York ----------------------------- Crystalline rocks ____________________ Consolidated sedimentary rocks ______ Black sand ------------------------- Beach sand ________________________ Page 132 133 134 136 138 139 141 142 144 146 146 148 151 158 158 160 161 161 162 162 162 163 163 163 163 164 165 166 166 167 167 167 169 169 170 170 171 172 172 172 173 174 174 177 178 179 179 180 180 180 Monazite localities—Continued North America—Continued United States of America—Continued North Carolina _________________________ Hypotheses of origin ________________ Crystalline rocks and placers in the Blue Ridge province .............. Spruce Pine district _____________ Madison County and Haywood County ______________________ Zirconia district ________________ Macon, Jackson, and Clay Coun- ties _________________________ Crystalline rocks in the western mona- zite belt in the Piedmont province_- Stokes County and Surry County- Wilkes, Alexander, Catawba, Cald- well, Burke, and McDowell Counties _____________________ Rutherford County and Cleve- land County _________________ Lincoln County and Gaston County ______________________ Outlying localities in the Piedmont province between the western and eastern monazite belts ............. Gaston County _________________ Mecklenburg County ____________ Rowan County and Davidson County ______________________ Crystalline rocks in the eastern mona- zite belt in the Piedmont province- - Stream deposits in the Piedmont province _________________________ Stokes County and Surry County- Wilkes, Iredell, Alexander, Cald- well and Catawba Counties- --- Burke County and McDowell County ______________________ Rutherford, Polk, and Cleveland Counties --------------------- Lincoln County and Gaston County ---------------------- Unconsolidated sedimentary rocks in the Coastal Plain province _________ Tuscaloosa Formation ___________ Black Creek Formation .......... Yorktown Formation ____________ Pleistocene deposits _____________ Stream deposits in the Coastal Plain province _________________________ Beach deposits _____________________ Oregon ________________________________ Stream deposits -------------------- Beach deposits _____________________ Pennsylvania ___________________________ Rhode Island __________________________ Crystalline rocks ____________________ Sedimentary deposits ________________ CONTENTS Page 180 184 189 189 191 192 193 194 195 196 198 205 206 206 206 206 207 207 208 209 212 217 225 226 226 226 226 227 227 228 229 229 229 230 231 231 231 Monazite localities—Continued North America—Continued United States of America—Continued South Carolina _________________________ Crystalline rocks in the western mona- zite belt in the Piedmont province_-_ Occurrences in the central Piedmont province ------------------------- Crystalline rocks in the eastern mona- zite belt in the Piedmont province-- Fluvial placers in the western Piedmont province _________________________ Cherokee County _______________ Spartanburg County ------------ Parts of Greenville County and Laurens County -------------- Parts of Greenville, Pickens, An- derson, Abbeville, Greenwood, Oconee, and Laurens Counties- Parts of Anderson, Abbeville, and Oconee Counties ______________ Unconsolidated sedimentary rocks in the Coastal Plain province --------- Deposits of Cretaceous age ------- Deposits of Tertiary age _________ Marine terrace plains of Pleisto- cene age _____________________ Stream sediments of Quaternary age _________________________ Coastal islands and beaches ------ South Dakota -------------------------- Tennessee ______________________________ Texas _________________________________ Utah __________________________________ Vermont _______________________________ Virginia ------------------------------- Crystalline rocks -------------------- Fossil placers ----------------------- Stream and beach deposits ----------- Washington ____________________________ West Virginia -------------------------- Wyoming ______________________________ Fossil placers of Cambrian age -------- Fossil placers of Late Cretaceous age-- Recent alluvial deposits ------------- South America _________________________________ Argentina ---------------------------------- Bolivia ------------------------------------ Brazil _____________________________________ Crystalline rocks and fluvial deposits ------ Rio de Janeiro ______________________ Sao Paulo __________________________ Minas Gerais _______________________ Espirito Santo ---------------------- Bahia ----------------------------- Paraiba and Rio Grande do Norte- _ -- Goias and Mato Grosso -------------- Page 23 1 232 233 233 234 236 238 242 246 249 251 252 254 255 258 2.60 262 262 263 264 265 266 266 268 268 269 270 270 271 271 273 273 274 274 275 275 275 276 276 284 284 286 286 VI CONTENTS Monazite localities—Continued Monazite localities—Continued South America—Continued South America—Continued Page Brazil—Continued Page Colombia __________________________________ 292 Beach placers __________________________ 287 Falkland Islands ____________________________ 292 Rio de Janeiro ______________________ 287 French Guiana _____________________________ 292 Espirito Santo ______________________ 288 Peru ______________________________________ 292 Bahia _____________________________ 290 Surinam ___________________________________ 293 Paraiba do Norte ___________________ 291 Uruguay ___________________________________ 293 British Guiana _____________________________ 291 Venezuela __________________________________ 294 Chile ______________________________________ 292 Bibliography _______________________________________ 294 TABLES. Page TABLE 1. World production of monazite, in short tons, 1880—1961, exclusive of output in Europe and U.S.S.R ....... 8 2. Amount of thorium oxide in monazite related to the geologic environment of the monazite _______________ 13 3. Relative abundance of minerals associated with monazite in concentrates from Ghana ____________________ 31 4. Frequency of mineral occurrence in concentrates from Ghana _________________________________________ 32 5. Thorium and rare-earth content of monazite from beach and dune placers along the southeast coast of the Malagasy Republic __________________________________________________________________________ 38 6—8. Mineralogical composition of monazite-bearing concentrates from streams: 6. Ribawe Mountain area, Mozambique ________________________________________________________ 40 7. Oban Hills area, Nigeria ___________________________________________________________________ 40 8. Calabar area, Nigeria ______________________________________________________________________ 41 9. Chemical analyses of monazite from Nigeria _________________________________________________________ 41 10. Mineralogical composition of concentrates from streams in the Mama area, Nassawara Province, Nigeria--- 42 11. Mineralogical composition of monazite—bearing concentrates from sands in Natal, Republic of South Africa- - 46 12. Geographic distribution of monazite-bearing streams in Ceylon as determined by heavy-mineral reconnais- sance from 1905 to 1910 ______________________________________________________________________ 56 13. Minerals associated with monazite in stream deposits in Ceylon --------------------------------------- 57 14. Chemical analyses of monazite from Malayan tin-bearing placers -------------------------------------- 63 15. Mineralogical composition and bedrock sources of monazite-bearing concentrates from streams in the Kuantan , area, Pahang, Federation of Malaya ___________________________________________________________ 65 16. Heavy minerals in charnockite and leptynite from Visakhapatnam, Andhra Pradesh, India ---------------- 69 17. Heavy minerals in clay, ocher, and sandstone in Madhya Pradesh, India ------------------------------- 70 18. Abundance of monazite and amount of thorium oxide in the monazite in ilmenite concentrates from beach placers on the Malabar coast of Kerala and Madras, India ------------- ' --------------------------- 71 19. Mineralogical composition of black sands from streams, dunes, and beaches between Errada and Pudimadaka, India ______________________________________________________________________________________ 72 20. Size and tenor of selected monazite placers in Cholla-namdo, Ch’ungch’ong-pukto, and Kyonggi-do, Korea“ 77 21-24. Mineralogical composition of: . 21. Heavy-mineral fraction of monazite-bearing concentrates from sandstone of Triassic age in north- eastern Timor ________________________________________________________________________ 82 22. Concentrates from beach placers, and reserves of monazite, along the South Pacific coast of Queensland and New South Wales, Australia -------------------------------------------------------- 85 23. Monazite—bearing concentrates from sandstones in the N arrabeen Series of Triassic age in New South Wales, Australia ---------------------------------------------------------------------- 90 24. Monazite-bearing concentrates from sedimentary rocks of Permian age in New South Wales, Australia- 90 25. Monazite produced in New South Wales and Queensland, 1950—54 ------------------------------------- 91 26. Monazite produced in Australia, 1948—61 ----------------------------------------------------------- 91 27-29. Mineralogical composition of monazite—bearing concentrates from: 27. Bay and ocean beaches of Victoria, Australia ------------------------------------------------- 94 28. Permian sedimentary rocks in the vicinity of Wandagee, Western Australia ----------------------- 95 29. Beach sand near Bunbury, Western Australia ------------------------------------------------- 97 30. Monazite produced in North Carolina, South Carolina, Idaho, and Florida from 1880 to 1960 ------------- 107 TABLES 31-41. 42. 43—46. 47. 48. 49—56. 57. 58. 59. 60, 61. 62. 63. 64-66. CONTENTS Mineralogical composition of : 31. Monazite—bearing concentrates from streams in the Goddard Hot Springs area, Baranof Island, Alaska- 32. Monazite-bearing concentrates from the Miller House-Circle Hot Springs area, Alaska _____________ 33. Monazite-bearing cassiterite concentrates from churn-drill line 94 in Boulder Creek valley in area underlaiu by limestone about 0.25 mile downstream from granite, Seward Peninsula, Alaska--__ 34. Heavy-mineral fraction of monazite-bearing natural beach sand along the Atlantic coast of Florida- -_ - 35. Monazite—bearing concentrates from sand on the Atlantic coast of Florida ________________________ 36. Black sand from the Atlantic beaches of Florida ______________________________________________ 37. Concentrates from beach sand, gulf coast of Florida ___________________________________________ 38. Natural black sand from the gulf coast of Florida _____________________________________________ 39. Heavy-mineral fraction of 17 samples of sand from marine terraces in southeastern Georgia ________ 40. Concentrates from the Chattahoochee River in the Coastal Plain of Georgia _____________________ 41. Concentrates from beach sand and natural concentrates on Sea Island beaches of Georgia __________ Chemical analyses of black sand from Sapelo Island and St. Simon Island, Ga __________________________ Mineralogical composition of: 43. Auriferous natural sand and concentrates from placers in Idaho ................................. 44. Sluice-box concentrates from placer materials along Ruby Creek, Idaho County, Idaho ____________ 45. Black sands from the Gold Fork placer, Valley County, Idaho __________________________________ 46. Concentrates from drill holes in Deadwood River alluvium, Valley County, Idaho _________________ Range in tenor of the main black sand minerals in the Bear Valley Creek placer, Valley County, Idaho__-_- Principal heavy minerals of concentrates from gold placers in the Boise basin, Boise County, Idaho ........ Mineralogical composition of: 49. Concentrates from the Camp Creek placer, Camas and Blaine Counties, Idaho ___________________ 50. Monazite—bearing suites of heavy minerals from alluvium of Recent age, glacial outwash gravel of Wisconsin age, and sand of Cretaceous age in Illinois ______________________________________ 51. Monazite-bearing suites of heavy minerals from Pleistocene loess and till in Iowa ................. 52. Concentrates from two monazite-bearing sand units of Pleistocene age in Louisiana _______________ 53. Monazite—bearing concentrates from sediments in the Mississippi Delta in St. Bernard and Plaque- mines Parishes, La., and Cat Island, Harrison County, Miss ________________________________ 54. Very fine monazite-bearing concentrates from sedimentary rocks of Eocene age in Mississippi _______ 55. Heavy-mineral fraction in the Lovewell Mountain and Keene quadrangles, New Hampshire ________ 56. Heavy-mineral fraction of monazite-bearing concentrates from coastal sediments of New Jersey _____ Semiquantitative spectrographic analysis of a bulk sample of a heavy-mineral deposit in the Point Lookout Sandstone exposed in the Shiprock area of New Mexico and Colorado ______________________________ Relative rank in production of monazite-producing counties in North Carolina by years of available data, 1900—1907 __________________________________________________________________________________ Abundance of monazite in crystalline rocks in the monazite belt in the western Piedmont province including estimates of the contribution of the monazite to the thorium in the rock ____________________________ Thorium, uranium, and rare-earth composition of monazite from: 60. Whiteside Granite exposed in Macon and Jackson Counties, N.C _______________________________ 61. Crystalline rocks in eastern Rutherford County, N.C __________________________________________ Amount of monazite in saprolite and residual soil in the drainage basin of Knob Creek, Cleveland County, N.C- Estimated abundance of monazite in crystalline rocks in the Shelby quadrangle, Cleveland and Rutherford Counties, N.C _______________________________________________________________________________ Thorium and rare—earth composition of monazite from saprolite of : 64. Sillimanite schist and biotite schist exposed in the Shelby quadrangle in Cleveland County, N.C-__- 65. Biotite gneiss in Cleveland County, N.C _____________________________________________________ 66. Toluca Quartz Monzonite and microcline-oligoclase-quartz pegmatite, and from unweathered vein quartz exposed in Cleveland County, N.C ________________________________________________ . Chemical analyses of rare earth plus thoria precipitates from monazite, Rutherford and Cleveland Counties, N.C _______________________________________________________________________________________ . Thorium, uranium, and rare-earth composition of monazite from the Cherryville Quartz Monzonite exposed in Cleveland County, N.C ____________________________________________________________________ . Mineralogical composition of monazite-bearing concentrates from alluvium in Stokes and Surry Counties, N.C- . Estimated tenor of monazite-bearing sediments in Stokes and Surry Counties, N.C ______________________ . Reserves of monazite and other minerals in alluvium in the valley of the First Broad River and contiguous parts of the valleys of Wards Creek, Duncans Creek, and Hinton Creek, Cleveland County, N.C ...... . Amount of monazite in: 72. Tuscaloosa Formation in North Carolina _____________________________________________________ 73. Pleistocene deposits in North Carolina _______________________________________________________ 74. Concentrates from stream deposits in the coastal plain of North Carolina ________________________ VII Page 109 110 113 127 128 128 130 130 138 139 140 140 147 150 152 156 157 159 161 163 164 164 165 168 173 175 177 182 187 194 198 200 201 202 203 203 204 205 209 209 221 227 228 228 VIII TABLES 75, 76. 77. 78. 79. 80. 81. 82. 83. 84. 85—87. 88. . Thorium and uranium composition of monazite from Spokane County, Wash ____________________________ 90. 91. CONTENTS Mineralogical composition of natural sand and concentrates from: 75. Streams in Oregon ________________________________________________________________________ 7 6. Beaches on the coast of Oregon _____________________________________________________________ Thorium and rare-earth composition of monazite in riflie gravel from Cherokee, Spartanburg, and Greenville Counties, S.C _______________________________________________________________________________ Amount of monazite related to class of sediment in the flood plain at the junction of Thicketty Creek and Little Thicketty Creek in Cherokee County, SC ________________________________________________ Mineralogical composition of concentrates from composited samples of alluvium from two drill holes in the flood plain downstream from the confluence of the North Tyger River and Middle Tyger River in Spar- tanburg County, SC _________________________________________________________________________ Distribution of detrital heavy minerals in concentrates from riffle sand and gravel in relation to source rocks in the drainage basins of Laurel Creek and other tributaries to the Reedy River in Greenville County, SC ________________________________________________________________________________________ Relative abundance of stable and unstable heavy minerals in terrace gravel and riflie sediments in Big Bea- verdam Creek and Little Beaverdam Creek in Oconee and Anderson Counties, S.C ____________________ Inferred amount of monazite in the Tuscaloosa Formation in South Carolina ____________________________ Mineralogical composition of monazite—bearing concentrates from Holley Creek and the Savannah River, Aiken County, SC __________________________________________________________________________ Abundance of heavy minerals related to average height of sand dunes on the Isle of Palms, Charleston County, 8.0 ________________________________________________________________________________________ Mineralogical composition of monazite-bearing concentrates from: 85. Sand of Tertiary age exposed in Fayette County, Tex _________________________________________ 86. River sand in southeastern Texas ___________________________________________________________ 87. Beach sands on the gulf coast of Texas _______________________________________________________ Chemical analyses of monazite from pegmatites at Amelia Court House, Va ______________________________ Mineralogical composition of monazite-bearing auriferous sands and concentrates from streams and beaches in Washington ______________________________________________________________________________ Mineralogical composition of heavy fraction of sandstone of Paleozoic age in the J. L. Jamison well 1, Monon- galia County, W. Va _________________________________________________________________________ ILLUSTRATIONS [Plates are in pocket] PLATES 1, 2. Map showing distribution of monazite in— 1. Asia, Australia, New Zealand, Antarctica, and the eastern part of Africa. 2. North America, South America, and the western part of Africa. Page 229 230 236 238 242 244 251 252 259 261 263 263 264 267 269 270 271 THE GEOLOGIC OCCURRENCE OF MONAZITE By WILLIAM C. OVERSTREET ABSTRACT The mineral monazite is a thorium-bearing anhydrous phos- phate of the cerium earths. On the basis of 731 analyses, it contains from 0 to 31.50 percent of Th02 (thorium oxide) and averages 6 percent. This mineral is the major source for thorium. Monazite and bastnaesite, a fluocarbonate of the cerium earths, are the principal ores for the cerium group of the rare earths. In industry, thorium and the rare earths are needed in gas mantles, cores of carbon electrodes, optical glass, colored glass, ceramics, glazes, glass polishing, pyro- phoric alloys, metallurgical processes, printing and dyeing, magnesium alloys, and radioactive energy applications. The use of thorium for energy purposes in the 1940’s led to political restrictions in the international traffic in monazite and to curtailment of publication of production data. Between 1880 and 1961 the world production of monazite, exclusive of Europe and the U.S.S.R., was at least 271,000 short tons. North Carolina was the earliest commercial source of mona- zite. In the United States monazite also has been mined in South Carolina, Florida, and Idaho. Most of the world output has come from Brazil, India, and the Republic of South Africa, but 12 other countries have produced the mineral; these countries include the Malagasy Republic, Mozambique, Nigeria, Republic of the Congo (Leopoldville), United Arab Republic, Ceylon, Federation of Malaya, Korea, Thailand, Republic of Indonesia, Australia, and Argentina. Monazite is distributed throughout Africa in a wide variety of geologic environments. Most commonly it occurs as an accessory mineral in Precambrian gneisses, schists, and mig- matites. Thorium-poor monazite forms concentrations in car- bonatites and other alkalic rocks associated with volcanic calderas exposed in Kenya, Uganda, Rhodesia and Nyasaland, and the Republic of South Africa. Thorium-rich monazite is concentrated in quartz-apatite-monazite veins formed by meta- morphic differentiation in the Malagasy Republic and the Republic of South Africa. The vein deposits in the Republic of South Africa ‘were one of the world’s most important com- mercial sources of monazite in the 1950’s. Placers in Africa have been but little exploited for monazite. The principal placers mined are along the southeastern coast of the Mala- gasy Republic, the cassiterite deposits of Nigeria, and at the delta of the Nile in the United Arab Republic. Monazite deposits in Asia include the world’s largest known reserves, which are in the coastal deposits of India, and the world’s most thorium-rich monazite deposit, which is mined in Ceylon. The resources of monazite in stream and beach placers of India, southeast Asia, and Korea seem to be im- mense. Successful commercial exploitation hinges on beneficia- tion of multimineral concentrates in which monazite is asso- ciated with ilmenite, rutile, cassiterite, wolframite, and gold. 238—813—67—2 Every State in Australia has been reported to have mona- zite, and the mineral has been found in New Zealand. Al- though abundant in the tin and tungsten placers of eastern Australia, monazite has been commercially unacceptable be« cause it generally contains less than 2 percent of Th02. An annual byproduct output as great as several hundred tons of monazite having 6.6 percent Th02 was maintained from 1948 until at least 1961 at extensive zircon-rutile placers along the southeastern coast of Queensland and the northeastern coast of New South Wales. Monazite occurrences in New Zealand are not economic sources for the mineral. The shores of the Antarctic Continent have been found to have ice-rafted grains of detrital monazite and glacially de- posited boulders of igneous and metamorphic rocks containing accessory monazite. The occurrences seem to have no eco- nomic importance. North America was the first important source of monazite in world commerce. Monazite was mined from fluvial placers in North Carolina and South Carolina from 1887 through 1917, but after 1895 Brazilian beach deposits became the main source for the mineral. Other exploited sources in North America are beach placers in Florida and stream deposits in Idaho. Large resources of monazite have been discovered in fossil placers that range in age from Precambrian to Late Cretaceous. Very large low-grade resources of monazite doubtless exist with ilmenite in the sedimentary rocks of the Atlantic and Gulf Coastal Plains and in oflshore deposits of the Southeastern United States and the gulf coast of Mexico. Little monazite has been found in the northern part of the North American Continent. Marine beaches and elevated bars along the southern coast of Brazil were the world’s main source of commercial mona- zite from 1895 through 1913, and a moderate extension of these beaches and bars has been found in Uruguay. The Brazilian ilmenite—monazite placers still constitute one of the larger known resources of monazite in the world, but new discoveries in Africa, Asia, Australia, and North America lessen their international importance. Stream placers in the interior of Brazil are virtually unexplored; they may consti- tute an immense resource. Monazite is widely distributed throughout the world as a minor accessory mineral in intermediate— and high-rank meta- morphic rocks derived from argillaceous sediments. Monazite is less commonly present in metamorphic rocks of like facies formed from arenaceous sediments and is rarely present in metamorphosed calcareous sedimentary rocks. The mineral is especially common in argillaceous schists, gneisses, and migmatites of the upper subfacies of the amphibolite facies and of the granulite facies. Monazite occurs in magmatic rocks ranging in composition from diorite to muscovite gran- ite, and in associated pegmatite, greisen, and vein quartz. In 1 2 THE GEOLOGIC OCCURRENCE or MONAZITE this group it is most commonly observed in biotite quartz monzonite, two-mica granite, muscovite granite, and cassiter- ite—bearing granite. Monazite is reported to be present in only a few places in quartz porphyry, aplite, or felsite, and has not been found in silicic lava. Monazite rarely occurs in syenite, except locally in nepheline syenite and syenite peg- matite, but is commonly abundant in carbonatite and related alkalic volcanic rocks and dikes. Monazite does not occur in mafic lavas or plutonic rocks but has been observed at one locality in mafic dikes and breccia of uncertain origin. Mona- zite forms in a wide variety of veins, from simple cleft fillings of the Alpine type through mesothermal quartz veins and alteration zones to hypothermal tungsten- and tin-bearing quartz veins and alteration zones. Locally it occurs in vugs and druses. Where monazite is an accessory mineral, it rarely makes up more than a few hundredths of 1 percent of the host rock. Several extraordinary enrichments of monazite are known in plutonic terrane where thorium-rich monazite is con- centrated in veins by metamorphic differentiation. Other im— portant concentrations in crystalline rocks are hydrothermal deposits of low-thorium oxide monazite in marble and primary volcanic or postvolcanic replacement deposits in carbonatite and alkalic rocks. Monazite eroded from crystalline rocks is transported by streams and accumulates in sedimentary rocks. Locally the processes of erosion and transportation may be varied and complex, and detrital monazite may have gone through several cycles before arriving at its present site. Processes of glacial and wind erosion and transport have released, moved, and concentrated monazite, but the most efiective agents are those related to rock weathering, fluvial transport, and accumulation of eroded material on beaches. Monazite is concentrated at the site of weathering, in streams, and on beaches, but the richest and largest concentrations are the beach deposits. Because rock weathering is most effective in warm humid en- vironments Where chemical weathering exceeds the rate of erosion, the greatest present placers are along beaches in tropi- cal and subtropical regions where monazite from the weath- ered rocks received preliminary concentration in coastal plain sediments and where these sediments are being eroded by the ocean. Monazite has a restricted occurrence in crystalline and sedi- mentary rocks. In crystalline rocks its presence can be related to conditions of temperature and pressure during metamorphic or magmatic crystallization. In metamorphic rocks the tem- perature and pressure conditions are shown by the grade of regional metamorphism. In magmatic rocks they are indicated by the composition of the rock and the degree of alteration of the wallrocks. In sedimentary rocks the occurrence of monazite is controlled by mechanical processes. Monazite in the epizone is characteristically of hydrothermal origin in veins, vugs, and disseminations associated with shal- low late-tectonic or posttectonic plutons of granitic rocks. It may be present in highly differentiated alkalic volcanic rocks but is rarely found in epizonal slate, phyllite, or schist. Mona- zite formed in the epizone, except in cassiterite—bearing gran- ites, tends to be lean in thorium. Monazite from epizonal plutons tends to have 200—800 percent more thorium than monazite from the wallrocks. Monazite in the mesozone is typically of metamorphic or magmatic origin. It is more abundant in granitic rocks than in metasedimentary rocks, but both rocks contain more mona- zite than their equivalents in the epizone. Monazite from the mesozone has more thorium than that from the epizone, and the amount of thorium in monazite from mesozonal magmatic rocks is about 50—200 percent greater than the amount of thorium in monazite from metasedimentary wallrocks. Monazite in the katazone is about equally abundant in meta- sedimentary and magmatic rocks and is much more common in both kinds of rock than it is in the mesozone or epizone. The amount of thorium in monazite from granitic rocks in the katazone is generally only 10—20 percent greater than the amount in monazite from metasedimentary rocks. An enrich- ment in thorium takes place in monazite formed in pegmatites in the katazone, and such pegmatites contain the most thorium- rich monazite known. Monazite in metamorphic rocks participates in a metamor- phic cycle whose chief feature is the loss of detrital monazite and the formation of authigenic metamorphic monazite. De- trital monazite is unstable in early stages of regional meta- morphism. It breaks down and shares its components with other minerals. As the grade of regional metamorphism in- creases, an environment is reached in which monazite becomes stable. Metamorphic monazite begins to form at a few centers of crystallization; these centers multiply with increasing grade of metamorphism until the rock finally contains far more metamorphic monazite than it originally had detrital monazite. The main sources for the metamorphic monazite are thorium, rare earths, and phosphorus held by other detrital components of the original sediment, chiefly hydrolyzates, clays, mica, and apatite. Many features of monazite in paraschists and paragneisses show that it is of metamorphic origin. Chief among them are direct relation between grade of metamorphism and amount of monazite in the rock; inverse relation between amount of monazite in metamorphic rock and grain size of original sedi- ment; lack of similarity between the range in grain size of particles of monazite in paraschists and paragneisses and the probable size range in the original sedimentary rock; correla- tion between physical properties of monazite and metamorphic grade of host rock; inclusions in monazite identical with meta- morphic minerals in the host rock; intergrowths between mona- zite and metamorphic minerals in the host rock; a reverse relation between monazite, allanite, and other thorium—bearing ‘ minerals in metamorphic rocks; and a direct relation between the amount of thorium in monazite and the grade of regional metamorphism. The last feature is particularly convincing: the average amount of thorium oxide in monazite from rocks ‘ of the greenschist facies is 0.4 percent; from rocks of the albite—epidote-amphibolite facies, 3 percent; from rocks of the amphibolite facies, 4.9 percent; and from rocks of the granulite facies, 8.9 percent. The presence and composition of monazite formed in mag- matic rocks are controlled by the degree of differentiation and spatial and temporal relations of the host. Differentiation under plutonic conditions gives granitic masses of batholithic dimension in which monazite is a minor accessory mineral, but large volumes of monazite—rich rocks are not formed. Differ- entiation of alkalic rocks forms large concentrations of tho- rium-poor monazite in carbonatite. Fractionation during crystallization produces thorium-rich monazite in pegmatites. Among magmatic rocks, monazite is most common in granitic rocks, particularly synkinematic granites in the upper sub- facies of the amphibolite facies and in the granulite facies. An increase in the average amount of thorium is noted in monazite from plutonic granitic rocks. If the metamorphic facies of the wallrocks is regarded as an index of plutonism, the average amount of thorium in monazite from granites in INTRODUCTION 3* different metamorphic facies is as follows: Greenschist facies, about 0.5 percent of Th02; lower and middle subfacies of the amphibolite facies, 4.2 percent; middle and upper subfacies of the amphibolite facies, 6 percent; granulite facies, about 8 percent. Monazite from pegmatites shows no detectable relation to the grade of metamorphism of the wallrocks, but pegmatite itself is rare in metasedimentary rocks of lower grade than the amphibolite facies. Fractionation of the fluid that yields the various rock types of complex pegmatites may well be a major control of the composition of the monazite. The average amount of thorium in monazite from veins in- creases from the epithermal to the hypothermal stages: 0.2 percent of Th02 in monazite from epithermal veins, 1.4 per- cent in monazite from mesothermal veins, and 3.4 percent in monazite from hypothermal veins. Geologic control of monazite in sedimentary rocks is related to the fact that monazite is stable in the weathering profile and to the fact that it has a greater specific gravity than ordinary rock-forming minerals. The sedimentary cycle of monazite be- gins with its release from host materials and ends with the onset of regional metamorphism. The geologic processes are domi- nated by mechanical agencies except at the outset when chemical weathering is active. Mechanical activity in the sedimentary cycle tends to concentrate monazite in placers. The richest monazite placers are formed by a succession of sedimentary cycles; for example, the monazite-enriched coastal plain deposits have been further concentrated through wave erosion and resorting on ocean beaches. Fossil placers of great antiquity and richness testify that intrastratal solution does not destroy 01d placers. The amount of thorium in monazite from placers varies from place to place in the world and depends upon the kind of crystalline rocks from which the monazite originally came. In general, the more plutonic the source, the more thorium the placer monazite contains. Because of mechanical blending during transport and deposition, bulk samples of monazite from various parts of a placer tend to have a more uniform composition than bulk samples of monazite from various parts of a mass of crystalline rock. Monazite is more common, and tends to have more thorium, in crystalline rocks in Precambrian terrane than in areas un- derlain by younger crystalline rocks. Geologic age, however, is only an indirect factor, because regions occupied by Pre- cambrian rocks contain a greater proportion of plutonic rocks than younger parts of the earth’s crust. Nonplutonic Pre- cambrian rocks or rocks otherwise petrologically unfavorable as a host are as lean in or as devoid of monazite as similar but geologically younger rocks; conversely, petrologically favor- able rocks of Paleozoic or younger age are as rich in accessory monazite as similar Precambrian rocks. INTRODUCTION PURPOSE AND SCOPE OF REPORT In this report, data on the geographic distribution, mode of geologic occurrence, composition, and com- mercial production of monazite are compiled from the literature. The report shows how the amount of thorium in monazite varies according to the origin of the monazite and describes the geologic cycles of mona- zite. In scope the report covers monazite occurrences throughout the world exclusive of Europe and the USSR. The few occurrences in Europe are, however, the subject of an extensive literature—more than 200 articles in 15 languages as of 1958—and the available reports on monazite in Russia, some of which are scientifically very important, numbered at least 118 by 1958. For each of the areas discussed, an efl'ort has been made to give the date of the local discovery of monazite and to cite reports between the discovery date and 1958. For some areas it has been possible to bring the review up to 1963. The area discussions are arranged alphabetically by continent and by country under each continent. Smaller political units in some large countries are also discussed alphabetically. Within a country the text generally follows geologic mode of occurrence in the following order: Crystalline rocks, sedimentary rocks, stream deposits, and beach deposits. In important areas a given mode of occurrence may be further subdivided geologically or geographically. A particular mode of occurrence generally is discussed in chronologic se- quence. Geographic names are used as they were known on January 1, 1962. The spelling accords with usage of the US. Board on Geographic Names where decisions are available. For clarity, some recommended names are followed in parentheses by the spelling found in the article cited. Place names for which recommended spellings are unavailable are given as they were spelled in the original article. Many old analyses are quoted in which the symbol Di is used for didymium. Didymium is unseparated neodymium (Nd) and praseodymium (Pr). The sym- bol Di is no longer employed in chemistry but has been retained here to show what the analyst originally reported. The stratigraphic nomenclature is that of the pub- lished sources and does not necessarily conform to that of the U.S. Geological Survey. ACKNOWLEDGMENTS Many analyses and reports of monazite are scattered in the literature. In large part they are in such obscure sources that they were virtually lost until the 1950’s when Margaret Cooper and her coworkers in the U.S. Geological Survey and US. Atomic Energy Commis— sion completed an extensive bibliography of uranium and thorium (Cooper, 1953a, b, 1954, 1955, 1958). Through this bibliography and the continuing aid of Miss Cooper, it became possible to recover the many reports and to review the literature on monazite in a practicable length of time. It is a pleasure to acknowl- 4 THE GEOLOGIC OCCURRENCE or MONAZITE edge the help Miss Cooper’s work has been to the preparation of this report. Acknowledgment is also made of the aid received from Amos M. White of the US. Geological Survey in searching the South American literature, particularly that of Brazil. DESCRIPTION OF MONAZITE DISCOVERY, SYNONYMY, AND SYNTHESIS The mineral monazite, an anhydrous phosphate of the cerium group of the rare earths, was named by Breithaupt (1829, p. 301). Breithaupt selected the name from a Greek verb meaning “to be solitary” in recognition of the rarity of the mineral at the site of its discovery near Miask in the Ilmen Mountains of Russia. Other names by which it has been known are turnerite (Levy, 1823), mengite (Brooke, 1831, p. 189), edwardsite (Shepard, 1837a, p. 163), eremite (Shepard, 1837b), kryptolith (Wtihler, 1846, p. 268), monazitoi'd (Hermann, 1847a, p. 28—29), phospho-cerite (Watts, 1849, p. 131), urdit (Forbes and Dahll, 1855, p. 226), korarfveite (Radominski, 1874, p. 766), and erikite (Fleischer, 1959). The name turnerite was actually proposed earlier than monazite, but because turneritc was not as well described as monazite, the name mona- zite, according to Frondel (1958, p. 150), was retained for the mineral after the two were found to be the same by J. D. Dana (1866) and Des Cloizeaux (1873). Long fragile prismatic crystals of monazite were formed artificially in 1875 by Radominski (1875, p. 305), who fused mixtures of cerium phosphate and cerium chloride. The crystals thus formed were as much as 0.75 inch long and resembled the natural mineral. Synthetic monazite was also produced through fusion methods at temperatures of 1,400°C by Karkhanavala (1956) . Dry-fusion syntheses of mona- zite, however, are of academic interest, as natural monazite is formed in environments in which water is free to move. The hydrothermal synthesis of monazite is of more petrogenic interest. Anthony (1957) pro- duced monazite in bombs from mixtures of dried cerium hydroxide gel and phosphoric acid at tempera- tures as low as 200°C, and Carron, Naeser, Rose, and Hildebrand (1958, p. 255—257) succeeded in synthe- sizing monazite from aqueous solutions of cerous chlo- ride and phosphoric acid by fractional phosphate pre- cipitation of pairs of rare—earth elements at a tempera- ture of 300°C and a pressure of about 90 atmospheres. Attempts by Carron, Naeser, Rose, and Hildebrand to form monazite at temperatures between 100° and 250°C were unsuccessful. PHYSICAL PROPERTIES Most monazite is various shades of yellow. Honey yellow to golden yellow and also shades of transparent pale yellow are commonly mentioned in descriptions of detrital monazite from stream and beach placers and in descriptions of accessory monazite from granulite and gneiss. Shades of yellowish brown, brown, reddish brown, red, yellowish green, green, and greenish brown are locally common in detrital monazite from streams and lakes and in accessory monazite in schist, gneiss, granite, and, particularly, pegmatite. Pale-orange- yellow to yellowish-gray, white, gray, or nearly color- less monazite is rare, but monazite having these colors has been found in veins and vugs. Black monazite, apparently owing its color to carbon, has been reported from pegmatite in Canada, a stream in Korea, and the beaches of Taiwan. Other than the possible relation of black to the presence of carbon, no chemical basis is known for the color of natural monazite. The streak of monazite is white, very pale yellow, or very pale brown. Monazite is transparent to subtransparent in small grains, but superficial alteration may render it opaque. Its luster is resinous to vitreous and is more brilliant in transparent grains than in subtransparent ones. Earthy monazite has been observed (Rose and others, 1958, p. 995). Monazite is brittle. It is commonly modified by conchoidal or uneven fractures. Its hardness is 5 to 51/2 on the Mohs scale; that is, it is as hard as or slightly harder than apatite but not as hard as ortho— clase. Rinds of superficially altered grains are softer than apatite. The specific gravity of Virtually pure (Ce, La) P04 is 5.15 i 0.05 (Frondel, 1958, p. 157). Differences in the chemical composition of monazite cause the spe- cific gravity to range from 4.6 to 5.47. Theoretically, an increase in the amount of thorium in monazite is accompanied by an increase in specific gravity (Her- mann, 1847b, p. 22). By actual analysis this relation has been difficult to demonstrate because the material accepted as monazite generally has not been pure; re— ported observations show that the theoretical increase in specific gravity which should accompany an increase in thorium, is only a poorly developed trend. Distinct cleavage is on the [100] plane, less distinct cleavage on the [010], and indistinct cleavage is rare on the [110], [101], and [011] planes. A strong part- ing occurs on the [001] plane and is thought to result from lamellar twinning (Frondel, 1958, p. 156). This parting, because of its perfection, has been question- INTRODUCTION 5 ably called cleavage (Dana, 1892). Parting is rarely present on the [111] (Palache and others, 1951, p. 693). Monazite occurs most abundantly as subhedral to round grains, the roundest grains being found gener- ally, but not exclusively, in detrital deposits. Small euhedral crystals from granitic rocks, schist, and gneiss are commonly tabular or wedge shaped and are accom- panied by a fair to large proportion of subhedral to round grains. Monazite is rarely found in grains larger than 0.02 inch across, and particles of monazite weighing more than a few milligrams are rare in placers. Some granular masses and exceptional large single crystals have been discovered in uncommon geologic occurrences. In the southeastern United States a fragment of monazite weighing nearly 60 pounds was found near Mars Hill, North Carolina (Pratt, 1916, p. 38). The original crystal from which the fragment came is estimated to have weighed nearly 100 pounds; the fragment is regarded as the world’s largest monazite crystal (Schaller, 1933, p. 436). Monazite has high magnetic susceptibility, which, as Mertie (1953, p. 5) showed, is an inherent property deriving from the paramagnetism of the rare earths (Yost and others, 1947, p. 12—19) in the mineral. This property led Murata, Rose, and Carron (1953, p. 300) to infer that it would be possible to isolate monazite of specific composition through the use of a magnetic separator if a quantitative relationship could be found between the composition and the paramagnetism. In 1961 Richartz (1961, p. 54—56) reported the magnetic separation of monazite into six fractions of decreasing magnetic susceptibility from grains almost as magnetic as ilmenite to grains almost as nonmagnetic as zircon. A systematic variation in the abundance of the rare earths was observed in the fractions: the most magnetic grains contained the least lanthanum and cerium and the most neodymium, samarium, gadolinium, and yttrium. Under ultraviolet radiation unaltered monazite neither fluoresces nor phosphoresces (Baskerville, 1903, p. 466), but it strongly absorbs violet, blue, and yellow radiation from an unfiltered mercury-vapor lamp and, as observed by the naked eye, assumes the green color of the unabsorbed radiation from the lamp (Murata and Bastron, 1956, p. 888). Monazite containing neo- dymium can be identified by a strong band in the yel— low and a faint band in the green if the mineral is observed by hand spectroscope in reflected sunlight (Derby, 1889, p. 111; Kithil, 1915, p. 8; Mertie, 1949, p. 630). Monazite undergoes no chemical or structural changes on heating to about 1,000°C in the atmosphere (Frondel, 1958, p. 157), but heating to 1,130°C sharp- ens the X-ray powder pattern and increases the spe— cific gravity, index of refraction, and birefringence (Karkhanavala and Shankar, 1954, p. 71). The mona- zite structure was reported to show change to the xenotime structure at high temperature (Gliszczynski, 1939, p. 15—16), but such change was not observed by Karkhanavala and Shankar. Liquid and gaseous inclusions are very rare, but they have been observed in monazite from localities in Brazil (Hintze, 1922, p. 354—355; Hussak and Reit- inger, 1903, p. 551). Sillimanite, rutile, hematite, mus- covite, biotite, quartz, epidote, apatite, magnetite, gal- ena, and garnet have been found in monazite from several localities, but the mineral generally lacks in- clusions. OPTICAL PROPERTIES Monazite is biaxial positive; relief is high and dis- persion is strong. The greatest, intermediate, and least indices of refraction are 1837—1849, 1.788—1.801, and 1.787—1.800 (Winchell, 1933, p. 139). The optic angle ranges from 5° to 15°. In thin section or immersion oils, monazite is almost colorless, pale yellow, or pale yellowish brown; it lacks pleochroism. Distinct ab- sorption is Y>X=Z. Like the other properties, the optical properties probably change with variation in the amount of thorium in monazite, but data are lack- ing (Frondel, 1958, p. 157). CRYSTALLOGRAPHY Monazite is monoclinic, in the prismatic crystal class, and is commonly tabular, wedge shaped, equant, or twinned (Frondel, 1958, p. 154—155). Summaries of crystal forms reported for the mineral have been given by Goldschmidt (1920, p. 51—57), Hintze (1922, p. 295—296), R. L. Parker (1937, p. 573), Palache, Ber- man, and Frondel (1951, p. 692), and Frondel (1958, p. 154). Interfacial angles of the same forms on crys- tals vary as the composition of the monazite varies. Comparison of crystals illustrated by Goldschmidt and geologic source of the monazite suggests that simple crystal form is common among monazite grains from vugs and low temperature veins and that complex forms tend to be common among monazite crystals from pegmatites. Monazite grains from plutonic gneisses and schists generally lack crystal form and are globular. Summaries of the unit-cell dimensions and X-ray data of monazite have been given by Gliszczynski (1939, p. 2—14), Parrish (1939, p. 652), Pabst (1951, 6 THE GEOLOGIC OCCURRENCE OF MONAZITE p. 62), Ueda (1953, p. 230—244), Karkhanavala and Shankar, (1954, p. 69—70), and Carron, Naeser, Rose, and Hildebrand (1958, p. 263—265). The size of the unit cell varies with variation in the abundance of the different rare earths, but systematic variation of the cell dimension and abundance of thorium has not been demonstrated (Kate, 1958, p. 230). According to Ahrens (1955, p. 299), monazite is rarely if ever met- amict, but Karkhanavala and Shankar (1954, p. 71) showed that X-ray data do not entirely support this contention and that thorium—rich monazite may attain a fairly high degree of metamictization. COMPOSITION Monazite is a thorium-bearing phosphate of the cerium earths. The cerium earths are the oxides of the metals lanthanum, cerium, praseodymium, neodymium, prometheum, samarium, and europium, which have atomic numbers that range from 57 for lanthanum to 63 for europium. The cerium earths include the ele- ments of lower atomic number in the group of elements called the rare earths. Rare earths of higher atomic number, uncommon in monazite, comprise oxides of the metals gadolinium, terbium, dysprosium, holmium, erb- ium, thulium, ytterbium, lutetium, and yttrium. Thorium, atomic number 90, is not a rare earth but is commonly associated with the rare earths in nature. It is classed with protactinium, uranium, and the trans- uranium elements in a radioactive group called the ac- tinides (Rankama and Sahama, 1950, p. 570). Thor- ium is about four times as abundant as uranium in the earth’s crust (Fleischer, 1953, p. 5). The first report identifying thorium in monazite was made by Kersten (1839, p. 186). The abundance of thorium and rare earths in mona- zite, the ratio of thorium to the rare earths, and the ratio of cerium to lanthanum vary widely. Thorium may be absent, as in monazite from tin veins in Bolivia (Gordon, 1944, p. 330) and in monazite from carbona- tite deposits in Africa (Mining World, 1954), or it may reach 31.5 percent, as it does in a rare variety of monazite from a pegmatite in India (Bowie and Horne, 1952, p. 2; 1953, p. 95). Murata and his asso- ciates have shown that systematic variations in the rare earths in monazite may be related to processes of fractional crystallization in nature (Murata and others, 1953, p. 292), but they have been unable to relate the content of thorium to that of any rare earth in mona- zite. The analyses given in this report make evident a correlation between the abundance of thorium in monazite and the geologic environment in which the monazite crystallized. Discussion of this correlation is reserved for the section on monazite in crystalline rocks. The cerium to lanthanum ratio is about 1:1 in nominal monazite [(Ce, La) P04] (Matveyefi, 1932, p. 228; Vainshtein and others, 1956, p. 161—162) and about 2.1 :1 in monazite from the Southeastern United States (Murata and others, 1953, p. 294; Murata and others, 1957, p. 148) . Uranium is commonly present in monazite but rarely reaches amounts greater than 0.5 percent. Plutonium and neptunium in extremely small amounts have been detected in monazite from North Carolina and Brazil (Seaborg, 1958, p. 78-79) and are probably present in thorium— and uranium-bearing monazite from other localities: Percent U (P”°/U)X10-13 North Carolina ________________________ Brazil ________________________________ 1. 64 . 24 3. 6 8. 3 Thorium, uranium, and samarium make monazite highly radioactive, a characteristic of the mineral first observed by Mme. Curie (1898, p. 1102). Some minor elements noted in its composition, like helium and lead, are at least partly of radiogenic origin. Small amounts of the yttrium earths occur in men- azite from many localities, but the ratio of the yttrium earths to cerium earths is always low. Small amounts of calcium, magnesium, ferrous and ferric iron, aluminum, zirconium, manganese, beryllium, tin, titanium, and tantalum have been reported in various analyses of monazite. As much as several percent of silica may be present. These constituents appear in careful analyses of selected materials and are not just found in analyses of concentrates consisting of mixtures of monazite and other heavy minerals (Wylie, 1948). To be marketable without penalties, monazite must have a total rare earths plus thorium oxide content of at least 65 percent (Lamb and others, 1953, p. 1355). PRODUCTION AND USE Monazite is the major source of thorium, and to- gether with bastnaesite, a fluocarbonate of the cerium earths, is the principal source of the cerium group of rare earths. An industrial need for thorium and the rare earths originated in 1883 when Carl Auer of Austria devel- oped an illuminating gas mantle composed of the ox- ides of lanthanum and other metals. The composition of the mantles was gradually modified until, in 1891, a mixture consisting of 99 percent of Th02 and 1 per- cent of CeOz was accepted as best. Immediately after World War I and the general introduction of the tung- sten—filament electric lamp, the declining demand INTRODUCTION 7 caused a corresponding decrease in the production of monazite; however, new applications for thorium and the rare earths were found, and by 1935 world output of monazite had returned to its pre-War level. The United States, Brazil, India, and the Republic of South Africa have been the chief sources of monazite, but small amounts have come from many other coun- tries. In the late 1950’s uranothorianite [thorianite] produced in the Malagasy Republic and leach liquors from uranium ores produced at Blind River, Ontario, Canada, became important sources for thorium. Be- tween 1880 and 1961 the world production of monazite, exclusive of the output in Europe and the U.S.S.R., was at least 271,000 short tons (table 1). The loca- tions of the monazite—producing countries and the places where monazite has been found but not pro- duced, exclusive of occurrences in Europe and the U.S.S.R., are shown on plates 1 and 2. The uses of the rare earths have been discussed by many authors in recent years, and the reader is re- ferred to their reports for details (see Lortie, 1943; Sanderson, L., 1943; West, C. A., 1944; Hammond, 1947; Johnstone, 1948; Mining J0ur., 1954a; Lamb, 1955a, b; Baroch, 1957; Crawford, 1957b; Heinrich, 1958; Paone, 1958; Lewis, 1959; and Gibson and others, 1959). The following summary is drawn from a re- view by Lamb (1955b, p. 6—7). The rare—earth fluor— ides and oxides are used as cores of carbon electrodes to produce brilliant white light for projection of mov- ing pictures and for high-speed photography. Lan- thanum oxide is used to make optical glass of high index of refraction and low dispersion. Cerium metal serves as a reducing agent in some metallurgical proc— esses and is a major component of pyrophoric alloys. Cerium oxide is an opacifier in porcelain and is used as an abrasive for polishing lenses and mirrors. Com- pounds of cerium are employed as oxidizing catalysts in organic preparations, as industrial driers, in various aspects of photography, and for the tanning of leather. Praseodymium and neodymium are used both to color glass and glazes and in mixtures to produce glass that absorbs ultraviolet light. A mixture of the rare earths in metallic form, called Misch metal, is used for pyro- phoric alloys. Misch metal added to aluminum im- proves the stress—rupture properties of aluminum alloys at temperatures of 700°—800°F. Addition of Misch metal to magnesium increases its resistance to creep at temperatures between 400° and 600°F. Added to hot- dip aluminum baths, the rare earth alloys substitute for fluxes in producing smooth coatings on steel. The rare earths added to molten steel reduce the size of the grain in the steel, increase its resistance to low- temperature oxidation, and improve its workability. Rare-earth metals are excellent deoxidizing agents for copper and nickel. Other uses include chemicals for the waterproofing, weighting, and dyeing of cloth, and chemicals for printing inks and phosphors. Improved processes for the separation of the rare earths, separa- tions formerly possible only through complex and costly fractional crystallization, should lead to their greater use by industry. Thorium in nonenergy applications since World War II has been used chiefly for the manufacture of gas mantles and in magnesium alloys where the addition of 3 percent of Th to 96.3 percent of Mg and 0.7 percent of Zr improves resistance to creep (Crawford, 1957a, p. 2—3) and maintains strength at elevated tempera- tures. Small amounts of thorium are consumed as refractories and polishing compounds, as chemicals and medicines, and in electric apparatus. Thorium-232, the common isotope of the element, is not a nuclear fuel but is a fertile material. By cap- ture of a slow neutron, the thorium-232 becomes thor- ium-233, a negative-beta emitter which has a half-life of 23 minutes and disintegrates into protactinium-233. The protactinium-233 has a half-life of 27.4 days, is a negative-beta emitter, and disintegrates into uranium— 233, an alpha emitter with a half-life of 1.63 X 105 years. Uranium-233 is fissionable by slow neutrons; hence, it is a possible fuel material for a sustained chain reaction (Glasstone, 1950, p. 400—401). The thorium-232 must be especially pure and free from the rare-earth metals. As little as 5 parts per million gadolinium in the thorium is enough to stop the re- action with slow neutrons (Franklin and Eigo, 1955, p. 80). Many aspects of the use of thorium in power reactors were discussed at the International Conference on the Peaceful Uses of Atomic Energy held in Gen- eva, Switzerland, in 1955. Reactors designed to supply electric power and breed uranium-233 from fertile thorium-232 were under construction by private indus- try and the US. Atomic Energy Commission in 1956 (Crawford, 1957a, p. 2-3). Political considerations resulting from the use of thorium for energy purposes as indicated in this para- graph have led to restrictions, beginning in 1944, in the international traffic in monazite and to curtailment of publication of production, export, and import data on thorium-bearing ores and compounds. Thorium is a source material under the US. Congressional Atomic Energy Act of 1946; thus, producers of thorium com- pounds in the United States must be licensed by the US. Atomic Energy Commission, and statistics on the domestic output of thorium and thorium compounds are classified as security information. In 1944 Aus- tralia forbade shipments of monazite to markets out- THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 1. —W orld production of monazite, in short tons, Africa [Data are from this report Asia Malagasy Republic Mozambique Nigeria Republic of South Africa Republic of the Congo United Arab Republic Ceylon Federation of Malaya 3 1943 _____________________ See footnotes at end of table. ‘3 3.5 DITRODUCTION 9 1880—1961, exclusive of output in Europe and U.S.S.R. unless otherwise noted] Asia—Continued Australial North America South America 1 Queensland India 4 Korea Thailand Republic of and New Florida Idaho North Carolina South United States 5 Brazil 5 Indonesia South Wales Carolina ___________________________________________________________________ 0.015 __________ 0 015 __-_______ __________________________________________________________________ (7) ____-_____ (7) ___-______ __________________________________________________________________ 12 12 815, 000 __________________________________________________________________ (7) __-._-_--_ (7) _________- ___________________________________________________________________ 65 __--______ 65 _-________ __________________________________________________________________ 273 -_________ 273 _____-____ ____________________________ (9) 787 787 m3, 307 ____________________________ 5 -______ -~______ 15 ___--____- 15 192 ____________________________ (9) _____-_ ________ 22 _________- 22 249 _____________________________________________________ 125 __.._____-- 125 2, 149 _____________________________________________________ 175 ____-_-___ 175 2,932 _____________________________________________________ 454 ___-__-___ 454 1,633 _____________________________________________________ 374 374 1,811 ______________________________________ (1') _______ _-____-_ 401 _-_____-__ 401 1, 328 _____________________________________________________ 387 44 431 3, 636 _____________________________________________________ 343 29 372 5, 357 _____________________________________________________ 447 225 672 4, 891 _____________________________________________ 12 2—3 349 74 423 4, 797 _____________________________________________ (12) 228 46 274 4, 891 _____________________________________________ (‘2) 155 56 211 5, 473 _____________________________ (9) -______ 12 196 75 271 7,121 _______________________________________ L-______ (12) 42 8 50 5, 994 932 ________________________________________________________ ‘2 __________ (12) 4, 064 1, 271 ________________________________________________________ (12) __________ (12) 3, 746 1, 382 __________________________________________________________________________________________ 1, 584 1, 328 __________________________________________________________________________________________ 661 1, 241 _________________________________________________________ 18 __________ 18 484 1, 447 ________________________________________________________ 19 __________ 19 __________ 2, 173 ________________________________________ 11 _________ 39 __________ 50 1, 252 2, 371 __________________________________________________________________________________________ 551 2, 266 ________________________________________ (14) ______________________________ (15) 161 1, 838 __________________________________________________________________________________________ 1,270 1, 411 __________________________________________________________________________________________ 366 140 __________________________________________________________________________________________ 127 276 ____________________________________________________________________________________________________ 697 ____________________________________________________________________________________________________ __________________________________________________ 1 ______-_ ____..-_-____ __-_______ ___-_______- 22 72 __________________________________________________________________________________________ 221 314 __________________________________________________________________________________________ 224 115 __________________________________________________________________________________________ 112 202 __________________________________________________________________________________________ 99 16 __________________________________________________________________________________________ 17 101 ____________________________________________________________________________________________________ 732 __________________________________________________________________________________________ 331 156 __________________________________________________________________________________________ 449 l, 130 _____________________________________________________________________________________________________ 4, 277 ____________________________________________________________________________________________________ 2, 943 __________________ 736 _________________________________________________________________________ 3, 451 __________________ 408 _______________________________________________________________ 460 5, 848 __________________ 433 ______________________________________________________________ 356 ____________________________ 136 ____________ ________ ________ -__--.._-____ --_______- ____________ 53 ‘5 4, 561 __________________________________________________________________________________________ 198 ‘5 3, 822 __________________________________________________________________________________________ 941 13 1, 430 __________________________________________________________________________________________ 1, 576 w 2, 099 ____________________________ (19) __________________________________________________ 1, 709 10 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 1,—World production of monazite, in short tons, [Data are from this report Africa Asia Year Malagasy Mozambique Nigeria Republic of Republic of United Arab Ceylon Federation Republlc South Africa the Congo Republic of Malaya 3 1944 _____________________________________________________________________________________ 1945 _____________________________________________________________________________________ 1946 _____________________________________________________________________________________ 1947 _____________________________________________________________________________________ 1948 _____________________________________________________ (5) __________ 7 1949 _____________________ (5) __________ 3 ______________________ 1950 _____________________ (5) __________ 80 ______________________ 1951 _____________________ (5) 41 1 __________ 84 1952 ______________________ 5 300 15 7 16 63 1953 _____________________ 5 5, 000 12 7 56 208 1954 _____________________________________________________ 5 9, 000 4 9 51 391 1955 _____________________ 72 ____________________ 5 9, 000 5 1 67 279 1956 _____________________ 168 __________ 86 5 9, 000 1 7 58 707 1957 _____________________ 331 0. 5 104 5 9, 314 __________ (7) 150 549 1958 _________________________________ . 1 64 5 8, 112 __________ (7) 124 479 1959 ___________________________________________ 15 5 2, 402 __________ 27 165 94 264 1960 _____________________ 471 1. 0 13 (5) __________ (7) 370 47 1961 _____________________ 503 . 2 8 (5) __________ (7) 239 780 Total _______________ 23 1, 547. 9 1. 8 294. 5 4 52, 131. 5 78 288. 1 1, 907 4, 071 1 Tasmania, 1900—05, small intermittent, unrecorded output; 1941, small amount in mixed concentrates, output unknown. 2 Argentina, 1 ton produced in 1956. 3 Exports. 41911—38 1948 from Mertie (1953, p. 6); 1940—47 from Krishnan (1951, p. 298); 1951, 1958 from . G. Parker, U.S. Bur. of Mines (written oommun., 1962). 6 1948—61 from J. G. Parker, U.S. Bur. of Mines (written commun., 1962, 1963).. 0 1895-1949 from Mertie (1953, p. 6); 1950—61 from J. G. Parker, U.S. Bur. Mmes (written commun., 1962). 7 Data on output not available. side the United Kingdom and the United States. The Atomic Energy Control Board of Canada regulates the development of thorium—bearing deposits and the dis- posal of ores. The Republic of South Africa has sim- ilar regulations. India restricted exports in 1946. At the beginning of 1951, Brazil ceased to issue export licenses but was, like India, considering offers of for- eign firms to process monazite within the country (Leonardos, 1950; Mattos Netto, 1951; Lamb, 1955b, p. 3). Rare earths extracted from the monazite would be exported and the thorium retained in the country of origin. By the end of 1952 India had opened a state-owned plant at Always, Travancore, for the proc- essing of monazite concentrates, and the Government of Ceylon had constructed a pilot plant at Katurkur- unda for placer monazite (Keiser, 1955, p. 1108). At 85.0 Paulo and Victoria in Brazil, thorium and the rare earths were produced from placer monazite at two plants of the Industrias Quimieas Reunidas S.A., and export markets were sought for the rare earths (Strod, 1953, p. 123; Crawford, 1957a, p. 5). National controls and agreements have become a part of the international traffic in monazite. 3 Surreptitious exports of concentrates, 1885—90 estimated by Leonardos (193 ,7a p. 3); possibly much less. 9 Small but unspecified output. 1° Exports from production in 1893—95. 11 Small, intermittent, and unrecorded output in the late 1800’s and early 1900’s. 11 Small production, not marketed. 13 Output between 1900 and 1918 exact years unknown; part may be from Swazi- land Protectorate. “ One producer, output unreleased, State unspecified. 16 Figure withheld to avoid disclosing company’s confidential data. The price of monazite has been affected by the polit- ical controls. It has increased from $50 to $60 per short ton prior to World War II to about $300 per short ton in 1955 for carload lots (f.0.b. West Chicago, Ill.). These prices are for material having a minimum of 55—60 percent of the rare earths plus thorium oxide (Franklin and Eigo, 1955, p. 78). In 1955 massive monazite having 55 percent total rare earths plus tho- rium oxide brought $0.13 per pound at ports in the United States, and the price per pound of monazite sand in the same year was $0.18 for 55 percent grade, $0.20 for 66 percent grade, and $0.22 for 68 percent grade. The prices are subject to negotiation, and quantity, quality, and the producer’s refining costs are the chief considerations (Franklin and Eigo, 1955, p. 78). Prices per pound of rare-earth oxides in 1958 ranged from $1.85 to $1.90 for optical—grade cerium oxide to $850 to $900 for europium oxide (Lewis, 1959, p. 3). Pound lots of mixed rare-earth chemical com- pounds (sulfate, hydrate, carbonate, chloride, nitrate, acetate, fluoride, and oxalate) brought $025—$165; pound lots of thorium compounds (carbonate, chloride, fluoride, nitrate, and oxide) sold for $3—$8.50, and INTRODUCTION 1880—1961, admin of output in Europe and U.S.S.R.-—Continued unless otherwise noted] 11 Asia—Continued Australial North America South America' Queensland India 4 Korea Thailand Republic of and New Florida Idaho North Carolina South United States 0 Brazil 0 Indonesia South Wales Carolina 1, 576 Is 2, 218 21 3, 928 __________________ 22 0. 1 __________________________________________________ 3 13 1, 724 ___________________________________________________________________________________________ 1, 135 18 66 (23) ___________________________________________________________ 1, 378 13 677 _________________________________________________ 24 40 _____________________ 24 40 1, 930 2, 258 ____________________________ 25 942 _____________________________ 2, 205 (7) ____________________________ 25 208 (15) (15) ______________________ (15) 3 2, 381 (7) ____________________________ 25 175 (7) (7) ______________________ 7 767 (7) 530 ____________________________ 25 374 (7) (7) ______________________ 1, 497 (7) (7) 3" 903 __________________ 25 129 (7) (7) ______________________ 2, 229 (7) (7) 26 845 ________ 314 25 283 (7) (7) (x5) __________ 1, 232 (7) (7) 26 1, 108 ________ 11 25 199 7) (7) ______________________ 1, 971 2, 976 (7) 26 560 ________ 122 25 216 15) 15) ____________ (15) 1, 219 (7) (7) 26 203 18 (7) 25 268 15) (w) ____________ (15) 15) (7) (7) 2“ 392 64 (7) 25 148 15) (15) ____________ (15) *4 2, 006 (7) 4, 122 26 355 1 (7) 25 474 (15) (15) ____________ (15) 24 722 1,162 (7) 2° 65 (7) ( ) 25 371 15) (24) ______________________ 24 770 1, 222 (7) 2" 11 (7) 25 386 ‘5) ______________________________ (23) l, 153 (7) 26 854 (7) 111 25 1, 739 (16) ______________________________ (23) 27 930 61, 637 29 9, 224 83 2, 276 3° 5, 912 31 12 3‘ 43 4, 926 32 557 17, 947 108, 270 16 Monazite and euxenite exports, first quarter only. 13 Small, unrecorded output of monazite-fergusonite concentrate. VI Total output also said to be 700 short tons during 1918—29. ’4 Shipments. 18 Madras. 2‘ Total for high-grade concentrate, low-grade concentrate, and concentrate. 1' Commercial production from beach sand, output not listed (Mining Jour., 3° Reported as concentrates containing 45—55 percent of RE201; also reported as 1954a, p. 97). 30 percent Ce, which may be high. 2° Additional 200 tons monazite-zircon concentrate shipped; tenor unknown. 21 Monazlte—zircou concentrate of unknown tenor; includes 1,598 short tons reported to contain 4-5 percent of monazite produced between 1942 and 1945 at the P’unggi placer in Kyfingsang-pukto. 22 Johnstone (1948, p . 615) . thorium metal cost $12.50—$19.55 per pound in 1961 (Baker and Tucker, 1962, p. 4). OCCURRENCE Monazite is widely distributed throughout the world as a minor accessory mineral in intermediate- and high- rank metamorphic rocks derived from argillaceous sedi- ments. It is less commonly present and less abundant as an accessory mineral in metamorphic rocks of like ranks formed from arenaceous sediments. Monazite is rarely present in metamorphosed calcareous or carbonaceous sedimentary rocks. It is especially common in pelitic schists, gneisses, and migmatites of the upper subfacies of the amphibolite facies and of the granulite facies. It may occur in magmatic rocks ranging in composition from diorite to muscovite granite and also in associated pegmatite, greisen, and vein quartz. In this group, accessory monazite is commonly observed in biotite quartz monzonite, two-mica granite, muscovite granite, and cassiterite-bearing granite. It has been more com- monly reported in porphyritic granite than in aplite or felsite, but it has not been found as a primary con- stituent of silicic lava. Monazite is very rarely found 31 Estimate, U.S. Bur. 28 Items listed only. 19 Includes 1,598 short tons of concentrate having 4—5 percent of monazite. 3° Includes low-grade concentrate. ‘1 Large output since 1949 not included. :2 Large output 1955—58 not included. Mines. in syenite but does occur locally in nepheline syenite and syenite pesgmatite; it is abundant in carbonatite from many localities and in related alkalic volcanic rocks and dikes. It is not known to occur in mafic lavas, nor has it been observed in plutonic mafic rocks, but at a diamond locality in Brazil, monazite has been found in weathered mafic dikes and breccia of un- certain composition and origin. Monazite is found in a wide variety of veins, from simple quartz—chlorite veins and epithermal deposits, through mesothcrmal quartz veins and siliceous alteration zones, to hypo- thermal tungsten- and tin-bearing quartz veins and alteration zones associated with topaz and other min- erals. Locally monazite occurs in vugs and druses. As an accessory mineral, monazite rarely makes up more than a few hundredths of 1 percent of its host rock. Several extraordinary enrichments of monazite are known in plutonic terrane where thorium-rich mona- zite is concentated in veins formed by metamorphic diflz'erentiation. Other important concentrations in crystalline rocks include low-thorium oxide monazite in marble and carbonatite. Pegmatite, although a source of monazite specimens for museums, is rarely a source of monazite ores and 12 THE GEOLOGIC OCCURRENCE OF MONAZITE where monazite is present, it tends to be sparse. Mona- zite from pegmatite may locally contain exceptional amounts of thorium, and the monazite richest in thor- ium comes from pegmatite. Erosion of crystalline rocks releases monazite for transport and accumulation in sedimentary rocks. Lo- cally the processes of erosion and transportation may be varied and complicated, the detrital monazite travel- ing through several cycles of transport and deposition before being lodged in the deposits Where it is pres- ently found. Processes of glacial and wind erosion and transport are known to have released, moved, and con- centrated monazite, but the most effective agents are those related to rock weathering, fluvial transport, and accumulation of weathered material on beaches. Rock weathering is especially effective in warm humid re- gions Where chemical weathering exceeds the rate of erosion and thick mantles of thoroughly weathered residuum accumulate. Chemical weathering reduces the variety of heavy minerals in the crystalline rocks and residuum until only the most inert ones remain to form eluvial deposits and to be washed into streams. In streams the heavy minerals are further winnowed and mechanically concentrated into fluviatile placers. Stream placers are not static deposits. A constant flow of monazite-bearing sediment moves downstream to interior basins or to the sea where the discharged sedi- mentary materials are further sorted. The tide, along- shore currents, waves, and wind continue to work and rework the monazite. These processes tend to concen- trate it with other insoluble heavy minerals in beach and dune placers. Economically the most important monazite deposits are beach placers, which are the end product of several stages of concentration of thorium and the rare earths. These stages are metamorphism which develops the primary source; weathering; con- centration in streams; concentration in littoral sedi- ments; and reconcentration in beach placers. Recent placers are generally in unconsolidated sedi- ments. Fossil placers are preserved in lithified sedi- ments of many ages, and accessory detrital monazite is found in sedimentary rocks, mainly sandstone, of all ages from Precambrian to Quaternary. Fossil placers are especially common in rocks of Precambrian, Cam- brian, Cretaceous, and Tertiary age. The review of the geographic and geologic occur- rence of monazite, forming the main part of this text, shows that monazite has a restricted occurrence in crys- talline and sedimentary rocks evidently resulting from geologic control. In crystalline rocks the presence, amount, and composition of monazite are affected by chemical and physical aspects of the geologic environ- ment, but in sedimentary rocks these relations are sub- ject to mechanical processes in the environment. Thus, general aspects of the occurrences of monazite can be related to geologic cycles in crystalline and sedimen- tary rocks. A semblance of control related to geologic age of occurrences is actually an expression of phys- ical and chemical factors in the cycles in crystalline rocks. In the following review of the occurrences of monazite, the economically most important deposits, beach placers, appear near the end of the discussion because they are interpreted to be the end product of the geologic cycle of monazite. CYCLES IN CRYSTALLINE ROCKS Occurrences of accessory monazite in crystalline rocks can be related to one of two formative cycles here called the metamorphic cycle. and the magmatic cycle. Occurrences seem to be more common in the meta- morphic cycle than in the magmatic cycle. For both cycles the geologic factors that generally and perva- sively control the abundance of monazite in the host rock and the amount of thorium in the monazite are the temperature and the pressure existing at the time monazite crystallizes. (See table 2.) In the meta- morphic cycle these factors are shown by the grade of regional metamorphism, but in the magmatic cycle the temperature and the pressure must be inferred from a greater variety of evidence. The role of temperature and pressure in the two cycles of monazite may be conveniently summarized by referring to the concept of three zones of rock forma- tion determined by regional geologic environment. The epizone has the lowest pressure and temperature condi- tions, the katazone has the greatest pressure and tem- perature, and the mesozone is intermediate. Monazite in the epizone is characteristically of hy- drothermal origin in veins, vugs, druses, and dissem- inations associated with shallow late tectonic or post— tectonic masses of granitic rock. Granitic rocks of the epizone, except the cassiterite—bearing granites, rarely contain monazite, and Where they do, monazite is sparse. Monazite is unreported in the efl’usive equivalents of the granitic rocks. Highly differentiated alkalic vol- canic rocks of the epizone contain low-thorium oxide monazite. Monazite is rarely found in epizonal slate, phyllite, or schist. Monazite formed in the epizone tends to be lean in thorium; locally, however, monazite from epizonal granite may be moderately rich in thor- ium. At those places in the epizone where monazite occurs in both granite and metasedimentary rocks, the amount of thorium in monazite from granite tends to be 200—800 percent greater than the amount in mona- zite from metasedimentary rocks. INTRODUCTION 13 TABLE 2.—Amount of thorium oxide in monazite related to the geologic environment of the monazite [Complete analyses are given in appropriate geographic parts of the report] Th0: in monazite (percent) Source of monazite Location Number of analyses Minimum Maximum Average Metamorphosed pelitic and arenaceous sedimentary rocks Greenschist facies: Talc schist ________________________________ Republic of the Congo (Léopoldville)__ l ________________ 0. 2 Sericite phyllite ___________________________ Minas Gerais, Brazil _________________ 2 0. 00 1. 09 . 54 Albite-epidote-amphibolite facies: Quartzite _________________________________ Federation of Rhodesia and Nyasaland- 1 ________________ 3. 07 Amphibolite facies: Middle and upper subfacies: Biotite gneiss _____________________________ New Zealand _______________________ l ________________ 5. 32 Mica schist and gneiss _____________________ Minas Gerais, Brazil _________________ 5 3. 3 6. 1 4. 9 Upper subfacies (sillimanite-almandine sub- facies) : Sillimanite schist __________________________ New Zealand _______________________ 1 ________________ 5. 47 North Carolina, U.S.A _______________ 16 3. 4 9. 0 4. 8 Biotite schist ______________________________ North Carolina, U.S.A _______________ 31 2. 1 6. 9 4. 8 Biotite gneiss _____________________________ North Carolina, U.S.A _______________ 9 3. 7 8. 8 5. 4 Muscovite schist __________________________ Pennsylvania, U S A _________________ 1 ________________ 4. 5 Sillimanite schist __________________________ Washington, U.S.A __________________ 2 3. 92 4. O6 3. 99 Granulite facies: Gneiss ___________________________________ Malagasy Republic __________________ 4 8. 6 10. 0 9. 4 Ceylon _____________________________ 2 8. 7 9. 26 9. 0 Feldspathic granulite in charnockite _________ Ceylon _____________________________ l ________________ 9. 81 Monazite-apatite metamorphic difierentia- Malagasy Republic __________________ 5 5. 28 12. 37 8. 43 tion assemblage. Monazite—apatite metamorphic difierentia— Republic of South Africa _____________ 1 ________________ 8. 01 tion assemblage. Metamorphosed calcarous sedimentary rocks Greenschist facies: Micaceous dolomite, magnesite—rich schist- _ __ Republic of the Congo (Léopoldville) _ _ l ________________ 0. 2 Amphibolite facies: Middle and upper subfacies: Calcite-diopside skarn ______________________ Quebec, Canada _____________________ 1 ________________ (1) Metamorphosed limestone intruded by granite Malagasy Republic __________________ 1 ________________ 1. 05 and calcite pegmatite. Migmatites Amphibolite facies: Kyanite—staurolite subfacies _________________ Central African Republic _____________ 1 ________________ 6 Sillimanite—almandine subfacies ______________ Northwest Territories, Canada ________ 1 ________________ 4. 8 North Carolina, U.S.A _______________ 3 5. 77 7. 72 6. 83 Upper subfacies(?) _________________________ Malagasy Republic __________________ 1 ________________ 6. 9 Sierra Leone ________________________ 2 10. 0 12. 6 11. 3 India ______________________________ 1 ________________ 10. 7 Metamorphosed pelitic and arennceous sedimentary rocks and mig'matites intruded by granitic rocks Amphibolite facies: Lower middle subfacies: Mica schist, mica gneiss, granite _____________ Georgia, U.S.A ______________________ 1 ________________ 4 Staurolite-kyanite subfacies: Staurolite schist, gneiss, granite _____________ Taiwan ____________________________ 6 3. 20 6. 79 5. 24 Georgia, U.S.A ______________________ 1 ________________ 4. 42 Staurolite schist, kyanite schist, mica schist, North Carolina, U.S.A _______________ 10 3. 30 7. 28 5. 1 gneiss, granite, pegmatite. Middle subfacies(?) : Schist, migmatite, granite __________________ Ghana _____________________________ 1 ________________ 6. 5 Mozambique ________________________ 1 ________________ 5 Mica schist, injection gneiss, granite _________ Korea ______________________________ 1 ________________ 6. 9 See footnotes at end of table. 14 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 2.—Amount of thorium oxide in monazite related to the geologic environment of the monazite—Continued Th0; in monazite (percent) Source of monazite Location Number of analyses Minimum Maximum Average Metamorphosed pelitic and arenaeeous sedimentary rocks and mimatites intruded by granitic rocks—Continued Amphibolite facies—Con. Middle and upper subfacies(?): Schist, granite _____________________________ Central African Republic _____________ 1 ________________ 7 Federation of Rhodesia. and Nyasaland- 1 ________________ 7. 1 Schist, granite gneiss, granite _______________ Korea ______________________________ 1 ________________ 5. 5 Brazil ______________________________ 5 5. 0 . 49 5. 8 Uféper subfacies(?) : chist, gneiss, granite ______________________ Nigeria _____________________________ 6 2. 30 8. 00 5. 03 Queensland and New South Wales, 8 6. 3 7. 4 7. 1 Australia. Garnetiferous gneiss, pegmatite ______________ Rio de Janeiro, Brazil ________________ 2 7. 2 7. 5 7. 3 Sillimanite—almandine subfacies: Garnet-sillimanite gneiss, two-mica granite---- Malagasy Republic __________________ 1 ________________ 4. 1 Garnetiferous sillimanite schist, biotite gneiss, North Carolina, U.S.A _______________ 36 3 7. 28 5. 5 quartz monzonite. Upper subfacies and granulite facies: Migmatite, gneiss, granite __________________ Malagasy Republic __________________ 18 5. 28 9. 44 7. 08 Gneiss, granulite, granite, pegmatite _________ Ceylon _____________________________ , 1 ________________ 10. 75 Gneiss, schist, granite ______________________ India ______________________________ 33 5. 0 11. 0 8. 6 Granulite facies: Granulite, granite _________________________ Ceylon _____________________________ l ________________ 14. 31 Igneous rocks Diorite and granodiorite: Diorite intrusive into slate __________________ Victoria, Australia ___________________ 1 ________________ 6.6 Granodiorite _____________________________ Mexico ____________________________ 1 ________________ :I: 4 Granodiorite, postkinematic(?) in upper Washington, U.S.A __________________ 1 ________________ 2.74 amphibolite facies gneiss. Unclassified granitic rocks ______________________ Victoria, Australia ___________________ 1 ________________ 5.20 Nova Scotia, Canada ________________ 3 2.9 8.6 5.3 California, U.S.A ____________________ 3 3.49 4.4 3.9 Montana, U.S.A ____________________ 2 4.1 6 5 Virginia, U.S.A _____________________ 1 ________________ 6.8 Bahia, Brazil _______________________ 2 3.76 10.05 6.90 Rio Grande do Norte, Brazil _________ 1 ________________ 8. 1 Sao Paulo, Brazil ___________________ 1 ________________ 1 .99 Granitic rocks ranked by metamorphic facies of wallrocks: Greenschist facies(?): Postkinematic granite ______________________ Uganda Protectorate ________________ 1 ________________ 47 Epidote-albite—amphibolite facies(?): ' Microgranite _____________________________ Sarawak ___________________________ 1 ________________ 6 . 8 Lower and middle subfacies of amphibolite facies: Granite __________________________________ Idaho, U.S.A _______________________ 34 2.2 6.24 4 Staurolite—kyanite subfacies of amphibolite facies: Granite __________________________________ North Carolina, U.S.A _______________ 1 ________________ 5.19 Synkinematic quartz monzonite _____________ North Carolina, U.S.A _______________ 2 4.21 4.64 4.42 Postkinematic quartz monzonite ____________ North Carolina, U.S.A _______________ 3 5.6 6.9 6.4 Middle and upper subfacies of amphibolite facies: Granite __________________________________ Korea ............................. 10 4.6 7.08 5.9 Granite, pegmatite _________________________ Korea _____________________________ 2 5.81 6.6 6.2 Granite, pegmatite, schist, gneiss ____________ Bahia, Brazil _______________________ 14 3.5 9.4 6.1 Espirito Santo, Brazil ________________ 15 5.2 7.09 6.1 Rio de J aneiro, Brazil _______________ l ________________ 5.87 Uruguay ___________________________ 1 ________________ 4. 1 Silliafmanite-almandine subfacies of amphibolite ames: Gneiss ___________________________________ New Hampshire, U.S.A ______________ 1 ________________ 2.48 Quartz monzonite _________________________ New Hampshire, U.S.A ______________ 1 ________________ 5.06 Granite __________________________________ New Hampshire, U.S.A ______________ 1 ________________ 3.25 Synkinematic quartz monzonite _____________ North Carolina, U.S.A _______________ 21 4.3 8.8 6. 1 Synkinematic quartz monzonite, gneiss, schist- North Carolina, U.S.A --------------- 36 4.47 7.84 5.94 South Carolina, U.S.A --------------- 29 3.00 7.85 5.77 Up er subfacies of amphibolite facies: (granite ---------------------------------- Korea ----------------------------- 1 ---------------- 7 . 3 New Jersey, U.S.A ------------------ 1 ---------------- 13.66 Gneissic biotite granite -------------------- Minas Gerais, Brazil ---------------- 1 ---------------- 6.7 See footnotes at end of table. INTRODUCTION TABLE 2.--Amount of thorium oxide in monazite related to the geologic environment of the monazite—Continued 15 Th0: in monazite (percent) Source of monazite Location Number of analyses Minimum Maximum Average Igneous rocks—Continued Granitic rocks ranked by metamorphic faces of wallrocks—Continued Upper subfacies of amphibolite facies to granu- lite facies: Granite __________________________________ Malagasy Republic __________________ 1 ________________ 7.8 Cassiilaierite- and (or) wolframite—bearing granitic roc : Granodiorite, granite ______________________ Tasmania, Australia _________________ 3 2 7.29 3 Granite __________________________________ Republic of South Africa _____________ 2 3 .48 3.51 3 .5 Granite(?) _______________________________ Burma _____________________________ 1 ________________ 7 Granite __________________________________ Federation of Malaya _______________ 14 .62 9.41 5.1 Thailand ___________________________ 2 5.7 5.7 5.7 Indonesia __________________________ 4 .00 3.4 1 .7 New South Wales, Australia __________ 17 .35 2.2 1.0 Cassiterite— and wolframite—bearing granite____ New South Wales, Australia __________ (2) (3) (3) 4. 11 Cassiterite granite, cassiterite pegmatite ______ New South Wales, Australia __________ 1 ________________ 6.18 Granite __________________________________ Queensland, Australia ________________ 3 1.2 3.0 2.3 Granite in slate ___________________________ Tasmania, Australia _________________ 2 2.5 3.0 2.7 Granite __________________________________ Alaska, U.S.A _______________________ 1 ________________ —4 A 1 Gneiss, granite, pegmatite __________________ Minas Gerais, Brazil _________________ 10 5.37 10.80 7. 7 p ite: Aplite and granite _________________________ Federation of Rhodesia and Nyasaland- 1 ________________ 6.2 Aplite-pegmatite __________________________ Colorado, U.S.A _____________________ 1 ________________ .94 Pegmlatite ranked by metamorphic facies of wall- roc s: Greenschist facies _________________________ India ______________________________ 2 2.25 3 .91 3.08 Greenschist or albite—epidote-amphibolite fa- India ______________________________ 1 ________________ 18.75 cies. South Australia _____________________ 2 10.7 19.4 15.0 Manitoba, Canada ___________________ 2 14.42 15.63 15.02 Albite—epidote—amphibolite facies or lower sub- Federation of Malaya ________________ 1 ________________ 6 facies of amphibolite facies. Japan ______________________________ 1 ________________ 5 .53 Staurolite-kyanite subfacies of amphibolite South Australia _____________________ 1 ________________ 8.0 facies. Connecticut, U.S.A __________________ 5 ~ 8.0 10.8 8.7 North Carolina, U.S.A _______________ 7 5.48 8.18 6.45 Middle subfacies of amphibolite facies(?) _____ Japan ______________________________ 1 ________________ 6.49 Ontario, Canada ____________________ 1 ________________ 7.32 Quebec, Canada _____________________ 4 3.38 4.25 3.64 California, U.S.A ____________________ 1 ________________ 22.29 Colorado, U.S.A _____________________ 1 ________________ 5.62 Virginia, U.S.A ______________________ 7 7.21 18.6 12.2 Middle and upper subfacies of amphibolite Korea ______________________________ 6 5.1 7.1 5.8 a01es. Upper subfacies of amphibolite facies ________ Malagasy Republic __________________ 1 ________________ 15.38 Mozambique ________________________ 1 ________________ 9 .84 India ______________________________ 9 4.0 31.50 10.2 Korea ______________________________ 5 9.49 10.7 9.8 Quebec, Canada _____________________ 1 ________________ 12.60 New Mexico, U.S.A _________________ 13 6.70 12.0 9.1 Bahia, Brazil _______________________ 1 ________________ 8.88 Espirito Santo, Brazil ________________ 1 ________________ 14 Goias, Brazil ________________________ 1 ________________ 9.8 Minas Gerais, Brazil _________________ 17 6.0 15.3 8.8 Rio Grande do Norte, Brazil __________ 3 .41 8.4 3.8 sec Paulo, Brazil ____________________ 3 10.93 11.6 11.3 Sillimanite—almandine subfacies of amphibolite North Carolina, U.S.A _______________ 50 3.8 11.2 6. 1 facies. Minas Gerais, Brazil _________________ 3 5.3 10.17 7 .3 Granulite facies ___________________________ Malagasy Republic __________________ 1 ________________ 1.83 Ceylon _____________________________ 9 4.91 28.20 10.81 Other pegmatite ___________________________ Federation of Rhodesia and Nyasaland- 2 2 .72 9 .36 6.04 Malagasy Republic __________________ 3 8.9 11.23 9.7 Swaziland Protectorate _______________ 3 6.5 7.0 6.7 Japan ______________________________ 7 6.0 11.73 9.4 Korea ______________________________ 1 ________________ 11.0 New South Wales, Australia __________ 1 ________________ 1.63 Queensland, Australia ________________ 2 5.73 6.22 5.97 Western Australia ___________________ 7 3.80 5.93 4.94 Bolivia _____________________________ 1 ________________ 10 . 1 Minas Gerais, Brazil _________________ 15 5.68 17.0 8.4 See footnotes at end of table. 16 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 2.~——Amount of thorium oxide in monazite related to the geologic environment of the monazite—Continued Th0: in monazite (percent) Source of monazite Location Number of analyses Minimum Maximum Average Igneous rocks—Continued Akalic rocks: Nepheline syenite _________________________ Greenland __________________________ 1 ________________ (1) Carbonatite _______________________________ Eederation of Rhodesia and Nyasaland_- 3 . 00 2. 2 (1). 8 enya _____________________________ 1 ________________ — Republic of South Africa _____________ 2 2. 07 2. 40 2. 23 Arkansas, U.S.A ____________________ 1 ________________ . 00 California, U.S.A ____________________ 6 1 3. 01 2. 3 Illinois, U.S.A ______________________ 1 ________________ 4. 4 Veins, alteration zones, and vugs Epithermal veins: Chlorite vein ______________________________ Republic of the Congo (Léopoldville)--- 1 ________________ 0. 2 Mesothermal veins and alteration zones: Auriferous quartz vein _____________________ South Australia _____________________ 1 ________________ . 18 Opaline alteration zone in granite ___________ Republic of South Africa _____________ 2 1. 5 2. 5 2. 0 Hypothermal veins and alteration zones: Quartz-fluorite-molybdenite vein _____________ Republic of South Africa _____________ 5 1. 0 4. 0 2. 8 Wolframite—scheelite-quartz vein _____________ Japan ______________________________ 1 ________________ 4. 51 Wolframite-quartz vein _____________________ Northern Territory, Australia _________ 1 ________________ 1 Cassiterite-wolframite—quartz vein ___________ Queensland, Australia ________________ 4 (2) (2) 4. 1 Disseminated with tourmaline and apatite____ South Australia _____________________ 1 ________________ . 16 Associated with talc, mica, and tremolite in South Australia _____________________ 1 ________________ 8 shear zone between veins composed of il- menite and hematite. Cassiterite—wolframite—topaz—quartz vein ______ Tasmania, Australia _________________ 1 ________________ 3 Hydrothermal dissemination in marble _______ Idaho, U.S.A _______________________ 1 ________________ . 85 Synkinematic quartz vein in sillimanite North Carolina, U.S.A _______________ 1 ________________ 6. 1 schist. Vugs: In quartz vein and spodumene pegmatite _____ North Carolina, U.S.A _______________ 1 ________________ 1. 48 In cassiterite—quartz vein ___________________ Bolivia _____________________________ 1 ________________ . 00 Druse in marble ___________________________ Bahia, Brazil _______________________ 1 ________________ . 05 1 Very low. 2 Range not given in source. Monazite in the mesozone is typically of meta- morphic or magmatic origin. It is a moderately com— mon accessory mineral in pelitic schists and gneisses and in syntectonic and posttectonic granitic rocks, par- ticularly quartz monzonite, two-mica granite, muscov- ite granite, cassiterite-bearing granite, and pegmatite. Monazite in the mesozone is more abundant in granitic rocks than in metasedimentary rocks, but both kinds of rock contain more monazite than their equivalents in the epizone. Monazite from rocks in the mesozone has more thorium than monazite from rocks in the epizone. The difference between mesozonal schist and mesozonal granitic rocks in tenor of thorium is not as great as the difference between these rocks in the epizone. Monazite from granitic rocks tends to contain from 50—200 percent more thorium than monazite from mesozonal schists and gneisses. Monazite in the katazone tends to be about as abund- ant in metasedimentary rocks as in granitic rocks; moreover, it is much more common in both kinds of rock in the katazone than in the mesozone. Sillimanite schist and gneiss, granulite, silicic charnockite, and synkinematic quartz monzonite generally have copious accessory monazite. Furthermore, monazite in the katazone is especially rich in thorium. In only a few places is the amount of thorium in monazite from granitic rocks in the katazone more than 10—50 percent greater than the amount in monazite from metasedi- mentary rocks, and it is generally only 10—20 percent greater. Monazite formed in pegmatites associated with katazone or mesozone rocks locally contains more thorium than monazite from any other rocks. METAMORPHIC CYCLE As long ago as 1900 the metamorphic origin of monazite in paraschist was clearly described by Derby (1900b, p. 219—220), and in 1913 Hess (1913, p. 1028) recognized its formation in regionally metamorphosed rocks. The contrary opinion that particles of mona- zite in paraschists and paragneisses are relict detrital grains, however, is still generally held. Observations in the present work confirm the metamorphic origin of monazite in paraschists and paragneisses, and also show that monazite participates in a previously unrec- ognized metamorphic cycle. The chief features of this cycle as defined in clayey sedimentary rocks are as INTRODUCTION follows: Detrital monazite in the sediment is unstable in early stages of regional metamorphism so that at the onset of metamorphism it breaks down and shares its components with other minerals and detrital mona- zite as such disappears. As the grade of regional meta- morphism increases, an environment is reached at which monazite is again stable, and metamorphic monazite begins to form at a few centers of crystalliza- tion, which multiply with increasing grade of meta- morphism. Many features of monazite in paraschists and para- gneisses described in the main part of this report sup- port the interpretation that this monazite is of meta- morphic origin. These features are the direct relation between grade of metamorphism and amount of mona- zite in the rock; the inverse relation between amount of monazite in the rock and grain size of the original sediment; the lack of similarity between the range in grain size of particles of monazite in paraschists and paragneisses and the probable range in size in the original sedimentary rocks; correlation between phys- ical properties of monazite and metamorphic grade of the host rock; inclusions in monazite identical with metamorphic minerals in the host rock; intergrowths between monazite and metamorphic minerals in the host rock; inverse relations between monazite, allanite, and other thorium-bearing minerals in metamorphic rocks; systematic variation in the amount of thorium in monazite related to grade of regional metamorphism of the host rock. A possible exception to the interpre- tation that monazite is metamorphic in origin is the occurrence of detrital monazite in quartzite. The literature shows that there is a direct relation in paraschists and paragneisses between the amount of monazite and the metamorphic facies of the host rock. Accessory monazite is exceedingly rare in the green— schist facies, rare to sparse in the albite-epidote-amphi- bolite facies, sparse to common in the amphibolite facies, and common to abundant in the granulite facies. This relation can be seen in monazite-bearing areas throughout the world but is especially evident along the east coast of the Malagasy Republic, in Ceylon, In— dia, Japan, the South Island of New Zealand, the Southeastern United States, and the Diamantina dis- trict of Brazil. The literature shows that at uniform metamorphic facies an inverse relation exists between the amount of monazite in a metamorphic rock and the coarseness of grain in the sediment from which the metamorphic rock was formed. Greater amounts of monazite are found in paraschists and paragneisses formed from argillaceous sediments than in rocks formed from arenaceous sediments. This relation holds even for thinly interlayered units of metamorphosed sandstone 17 and shale; monazite is chiefly in the biotite—rich or sillimanite-rich layers formed from the shaly compo- nent and is sparse or absent in quartzo-feldspathic lay- ers formed from the more sandy components. That a greater amount of monazite is found in schist and gneiss of pelitic origin than in rocks of equivalent facies formed from sandstone and graywack is a re- versal of the usual distribution of detrital heavy min— erals in shale and sandstone. Coarse clastics ordinarily are richer in heavy minerals—including monazite— than fine-grained sedimentary rocks. Obviously some process other than initial sedimentary concentration is required to account for the inverse relation that exists after metamorphism. This inverse relation has received the most study in the metamorphic rocks of North and South Carolina. A general lack of similarity has been noted in North and South Carolina, Ceylon, and the Malagasy Repub- lic between the range in grain size of particles of mona— zite from paraschists and paragneisses and the prob— able range in grain size in the original sedimentary rocks. Poorly sorted monazite having a wide range in grain size is typical of schists and gneisses through the amphibolite facies, but at the granulite facies the range in grain size tends to become narrow. At low and in- termediate metamorphic facies, a wide range of grain size in monazite from single samples of schist and gneiss can be interpreted to indicate a mode of forma- tion independent of hydraulic transport and sedimen— tary deposition because the sedimentary process tends to perfect the sorting of heavy minerals (Trainer, 1930, p. 197). A reduction in range of grain size that corre- lates with increase in metamorphic grade is unlikely to reflect sedimentary sorting. The specific gravity and the unit-cell size of mona- zite from metamorphic rocks seem to vary with meta- morphic grade. Data are incomplete but suggest that the specific gravity of monazite increases and that unit- cell size decreases as the metamorphism of the host rock increases. Inclusions in monazite at several localities are iden- tical to metamorphic minerals in the host rock. Mona- zite also occurs intimately intergrown with meta— morphic minerals in the host rock. These relations can be interpreted as resulting from the metamorphic growth of monazite. Noteworthy examples are inter- growths with sericite and chlorite in quartzite from Transvaal Province, Republic of South Africa; inter- growths with and inclusions of biotite and kyanite from North Carolina; intergr0wths with kyanite from Minas Gerais, Brazil; and intergrowths with and in- clusions of sillimanite from New Zealand and Con- necticut. 18 THE GEOLOGIC OCCURRENCE or MONAZITE A striking relation exists in metamorphic rocks— that is, as monazite becomes more abundant, allanite and (or) sphene become less abundant. At low meta- morphic facies, allanite and sphene are common and monazite is sparse. As metamorphic facies increases to the staurolite—kyanite subfacies, the quantity of the three minerals increases. Above that subfacies, allanite and sphene decline in abundance and monazite in- creases. Monazite is common, but allanite and sphene are uncommon in the sillimanite-almandine subfacies. In the granulite facies, monazite is rarely accompanied by allanite or sphene; however, it may be associated with thorite and thorianite. The literature contains much evidence that allanite and sphene proxy for monazite as a host mineral for thorium at low grades of regional metamorphism, and it gives some evidence that thorite and, especially thorianite, proxy for mona- zite in rocks of highest facies. This relation between monazite and the minerals mentioned seems to be an expression of a sequential partition of thorium among mineral species in metamorphic rocks, beginning with thorium in chlorite, biotite, apatite, garnet, and allan- ite in the low grades, changing to allanite, sphene, and monazite in the middle grades, and to monazite, thorite, and thorianite at the highest grade. If, as sometimes supposed, the monazite consists of relict detrital grains, the arrangement here described is inexplicable. The amount of thorium in monazite from metasedi- mentary rocks increases as the metamorphic facies in- creases. The results of 7 31 analyses of thorium in monazite are grouped in table 2 according to geologic environment and geographic distribution. Many of the analyses are of monazite from placers; thus, it has been necessary to use a geologic classification of sources that describes the crystalline rooks from which the placer monazite came. The first 230 analyses in the table are of monazite from metasedimentary rocks or from distributive provinces in which metasedimentary rocks are the dominant source. These analyses are followed by those of monazite from igneous rocks or from distributive provinces in which igneous rocks are dominant. The analyses disclose, despite their wide range and their various inconsistencies, that for meta- morphic rocks the average amount of thorium oxide increases as follows: Th0: Metamorphic grade of host rock for monazite Metaaedimentury Metusedimmtary 106 8 me a and migmatite Greenschist _____________________ 0. 4 (1) Albite-epidote-amphibolite ________ 3 (1) Amphibolite _____________________ 4. 9 6. 1 Granulite _______________________ 8. 9 9. 4 1 Not represented among analyses. No thesis of sedimentary deposition and preserva- tion of relict detrital monazite through metamorphism can account for this worldwide direct relation between the amount of thorium in monazite and the meta- morphic grade of the host rock. Monazite in some quartzites locally may represent fossil placers, although in other quartzites it seems to be of metamorphic origin. Quartzite and conglomer- ate in the Mkushi district of the Central Province of the Federation of Rhodesia and Nyasaland contain concentrations of monazite that are probably fossil placers, but the amount of thorium in the monazite varies widely (O’Brien, 1958). The metamorphic grade of the monazite—bearing quartzites also varies widely. Vickers (1956a, p. 173—185) reported thorium- rich monazite in fossil placers that occur in Goodrich Quartzite in the Palmer area, Marquette County, Mich., but did not give any data on the regional metamorph- ism of the area. Quartzite and conglomerate exposed in the Sub Nigel mine, Transvaal Province, Republic of South Africa (Mendelssohn and Marland, 1933; Liebenberg, 1955, p. 147—148), apparently contain both detrital and metamorphic monazite, but the composi- tion of the monazite is unknown. Fossil placers in quartzite, usually of low metamorphic grade, are re- ported from other localities, but such examples of relict detrital monazite are scarce compared to the extensive outcrops of monazite-bearing schists and gneisses which underlie hundreds of thousands of square miles of the earth’s surface. Monazite is rarely found in metasedimentary carbon- ate rock, and where found (Malagasy Republic, Feder- ation of Malaya, Idaho, and Brazil), it seems to have been introduced hydrothermally or brought in by peg- matites. Monazite in metamorphosed carbonate rock is very lean in thorium. Although the calc-silicate rocks are rich in sphene in many localities, these rocks are not known to contain monazite, but this mineral may have been overlooked. Monazite has been reported from carbonaceous sedi— mentary rocks which are highly metamorphosed but not from those which are slightly metamorphosed. Layers or veins of graphite in granitoid gneiss at two localities in Brazil were shown by Derby (1902) to contain as much as 7 percent of monazite. Derby stated that graphite-sericite schists in the same areas lack monazite. He suggested that this relation might be used to discriminate between graphite of possible igneous origin, which was thought to be associated with monazite, and graphite of sedimentary-metamorphic origin, which was thought to lack monazite. That INTRODUCTION 19 metamorphic facies is the key to the presence or ab- sence of monazite seems more probable. In North Carolina monazite is present in graphite—rich silliman- ite schist of the amphibolite facies but is absent from graphite phyllite of the greenschist facies. Retrogressive regional metamorphism might be ex- pected to afl'ect the abundance and composition of monazite in appropriate rocks. The small amount of evidence on this point in the literature is conflicting. Retrogressive metamorphism may have had no sig- nificant effect on monazite having about 8 percent of ThOZ at Myponga Hill, South Australia (Rowley, 1956, p. 63). It is remotely possible, however, that, prior to retrogressive metamorphism, this monazite was much richer in thorium. Nearby unmetamorph— osed rutile—bearing pegmatite contains monazite having 19.4 percent of Th02 (Wylie, 1950, p. 165). Sericite phyllite said to have been formed by cata- clastic deformation of muscovite granite at 85.0 J 050 da Chapada, Brazil, contains fragments of monazite crystals which were interpreted by Moraes and Guim- araes (1931, p. 524) to have been broken by the cata- clasis. Interestingly, this monazite seems to contain only! 1.09 percent of Th02 (Hussak and Reitinger, 1903, p. 560), a quantity that is considerably less than might be expected in monazite from muscovite granite but that is consistent with the amount to be expected in monazite from sericite phyllite. Although retrogressive metamorphism might be ex- pected to lead to the replacement of monazite by allan- ite, sphene, apatite, mica, or chlorite; no examples of this replacement are known. Authigenic monazite in most metasedimentary rocks is derived from elements in other minerals and gels or precipitates in pelitic rocks. Original detrital mona- zite may supply only a small amount of the elements that form metamorphic monazite. Indeed, the general absence of monazite in many low—grade metamorphic rocks may be due primarily to a general sparseness of detrital monazite in sedimentary sequences, rather than to a loss of detrital monazite resulting from the insta- bility of the mineral at the onset of regional meta- morphism. The distribution of thorium in sedimentary rocks can be used as a guide for an interpretation of the source of authigenic monazite in metamorphic rocks. A clear relation was shown by Jafl'e and Hughes (1953) between the radioactivity and the grain size of sediment in samples from the bottom of the Chesapeake Bay. Silt and clay were found to be more radioactive than fine sand, and fine sand proved to be more radioactive than coarse sand. Breger (1955, p. 63) showed that in marine sediments the concentration of thorium does not increase with nearness to a land mass. Adams and Weaver (1958, p. 396-399, 412-413), Murray and Adams (1958, p. 267—268), Adams, Richardson, and Templeton (1958, p. 272), and Pliler and Adams (1959a) reported that thorium is more abundant in offshore shales than in nearshore sands and beach sediments. The data on the abundance of thorium in shales was summarized by Adams and Weaver (1958, p. 402), who reported a mean of 12:1;1 ppm Th in the average shale: Mfg”. T)h pm Gray—green shale, America (avg of 52 analyses) ________ 13. 1 Shales, Russian platform, U.S.S.R. (4795 analyses) ______ 11 Bentonites, North America (avg of 69 analyses) ________ 24 Average shale (estimate) _____________________________ 12 :1: 1 Thorium in shale and thoroughly weathered crystal- line rocks was found principally in fine—grained sec- ondary. minerals, probably hydrolyzates, or fixed in clays (Pliler and Adams, 1959a, b). The data on thorium are much less complete for sandstone and sand than for shale. Graywacke was estimated by Adams and Weaver (1958, p. 413) to contain possibly as much thorium as the source rocks from which it was derived, or possibly as much as shale, but analyses were not given. Analyses of com— mon sandstone and beach sand, and of sandstone and beach sand enriched in heavy minerals, presented by Murray and Adams (1958, p. 263), showed that common sand contains from $0 to )4 as much thorium as the average shale. Murray and Adams (1958, p. 268) stated that the average amount of thorium in sandstone is difficult to determine because no information is available on placers in sandstone. In common sand very little of the thorium is associated with heavy detrital grains. Murray and Adams (1958, p. 263) gave 18 analyses of sand from the United States which showed a wide range in thorium content: Number of Average Th samples (ppm) Berea Sandstone _________________________ 1 4 Ottawa, Berkshire, Roubidoux, and Saint Peter Sandstones ______________________ 4 1 0. 8 Gallup Sandstone ________________________ 1 362 Sand from Placer County, Calif ___________ 1 24. 6 Beach sand from Florida __________________ 1 159. 8 Beach sand from Galveston Island, Tex--- - 10 2 1. 9 1 Range, 0.67—0.93. 9 Range, 1.5—2.2. 20 Five samples of sandstone analyzed by Adams and Weaver (1958, p. 399) had the following thorium content: Source of sandstone (132%) Zion Canyon, Utah _________________________ 5. 4 Similar, Calif _______________________________ 4. 5 Brownwood, Tex ___________________________ 1 14. 4 Cantuar, Alberta ___________________________ 1.0 Do ____________________________________ 3. 0 l Thorium by gamma-ray spectral analysis; other samples by alpha activity—fluorometric uranium method. Probably the average sandstone has between 2 and 24 ppm of Th, the average possibly being 5.4 ppm (Rankama and Sahama, 1950, p. 573; Adams and Weaver, 1958, p. 402, 413; Murray and Adams, 1958, p. 265). Results of work by Jaffe and Hughes (1953), Breger (1955, p. 63), and Murray and Adams (1958, p. 263) suggested that in ordinary sedimentary sequences the amount of thorium is less in sandstone than in shale. The distribution of monazite in metamorphosed shale and sandstone in North Carolina was shown by Over- street, Yates, and Griflitts (1963a, pl. 1) to resemble the distribution of thorium in unmetamorphosed shale and sandstone. The average amount of thorium in many samples of monazite from each type of metasedi- mentary rock was identical, but the amount of mona- zite in metamorphosed shale was twice the amount of monazite in metamorphosed sandstone. In both rock types the amount of thorium attributable to monazite was much less than the amount of thorium in average shale or sandstone. The source of monazite in the average metasedi- mentary rock is, therefore, interpreted to be thorium, rare earths, and phosphorus dispersed among the clays, mica, and apatite in the unmetamorphosed sediments. During progressive regional metamorphism these com- ponents differentially pass from one mineral phase to another. In the early stages of metamorphism, chlo- rite, biotite, garnet, and other minerals are the princi— pal hosts for the rare earths, thorium, and phosphorus. As the host minerals disappear and new mineral phases enter or the composition of the earlier formed minerals changes to accommodate higher temperature, pressure, and stress, the components are held by diiferent mineral phases among which monazite becomes more common as the grade of metamorphism rises. As the grade of metamorphism increases, the amount of thorium in the crystallizing monazite also increases. It is not known if this increase in thorium only affects monazite crys- tals forming at a given stage in the metamorphic history of the rock, or if there is continuous reaction between early formed monazite and other thorium- bearing minerals in the host rock. Inasmuch as the THE GEOLOGIC OCCURRENCE OF MONAZITE amount of thorium in separate samples of monazite from the same metasedimentary rock tends to vary widely (Overstreet, Yates, Grifiitts, 1963a, p. F14), the reaction of earlier formed monazite was probably slow and incomplete, and the rate of diffusion of thorium was probably low. Although the amount of thorium held in monazite formed at the upper sub- facies of the amphibolite facies is only about one-tenth of the amount of thorium in the average unmetamor- phosed shale or sandstone, adequate thorium is present in other components of the schists and gneisses to allow the greater nucleation of monazite and to supply the higher tenors in thorium in the monazite found in schists and gneisses of the granulite facies. A rela~ tively high rate of nucleation and a relatively low rate of diffusion in granulite may cause the abundance of fine-grained monazite characteristic of gneiss in the granulite facies. At the highest grade of regional metamorphism, some thorium in the rocks crystallizes as thorite and thorianite. Metamorphic differentiation of the granulite facies even leads to the segregation of aggregates of monazite and apatite and of thorianite, which migrate into veins. Examples of such aggre- gates are known in the Malagasy Republic. Monazite seems to have been introduced hydro- thermally or by pegmatites into a few metamorphosed carbonate sedimentary rocks. In general, however, the sedimentary carbonates contain very little thorium (Breger, 1955, p. 66). According to Adams and Weaver (1958, p. 402, 404), the amount of thorium in limestone correlates reasonably well with the abundance of insoluble matter, particularly shaly material, in lime- stone: Mean Th Source of limestone (ppm) North America: 54 individual samples ___________________________ 1. 7 25 aggregates comprising 516 samples _____________ 1. 1 Russian platform: 13 aggregates comprising 5,475 samples ____________ 2. 4 Organic debris is associated with concentrations of detrital monazite in Recent placers which may be covered by peat, muck, and carbonized wood. Black shale was reported to contain from 1.6 to 28 ppm Th (Adams and Weaver, 1958, p. 396), and detrital mon- azite is known in sediments underlying coal in Australia. Original detrital materials are probably the source of monazite in graphitic schist and gneiss, but the source of monazite in graphite veins or layers is uncertain. MAGMATIC CYCLE The magmatic cycle is here taken to refer to occur- rences of monazite in solidified mobile rock material. It includes monazite-bearing rocks formed by partial or complete anatexis of sediments in orogenic belts. INTRODUCTION 21 Also included are monazite-bearing veins and altera- tion zones related in origin to these rocks. Differentiation under plutonic conditions yields gra- nitic masses of batholithic dimension in which mona- zite is a minor accessory mineral, but large volumes of monazite-rich rocks are not formed. Differentiation locally produces monazite—rich veins in the mesozone and epizone. Extreme differentiation of alkalic rocks forms large concentrations of thorium-poor monazite in carbonatite. Fractionation during crystallization in the magmatic cycle produces thorium—rich monazite in pegmatites. Among rocks formed in the magmatic cycle, accessory monazite is most common in granitic rocks, particularly in plutonic synkinematic granites emplaced contemporaneously with folding and meta- morphism of wallrocks; thus, of the 478 samples of monazite from occurrences in the magmatic cycle (table 2), none is from a mafic igneous rock, only 1 is from diorite, and 2 are from granodiorite, whereas 254 are from granite and 204 are from pegmatite.1 Plutonic mafic rocks and their extrusive equivalents are not known to contain monazite, but the mineral has been reported from weathered mafic dikes and igneous breccia of uncertain composition intrusive into quartz- ite in the Diamantina district of Brazil (Derby, 1899, p. 348; 1900a, p. 209—213; Thompson, L. S., 1928, p. 709). The monazite-bearing mafic igneous rocks are described as sheared diabase, quartz-free greenish schist, and igneous breccia composed of blocks of quartzite in mafic material resembling the dikes. Com- position of the monazite is unreported. Except for the greenish schist in the Diamantina district, metamor- phosed equivalents of mafic igneous rocks are not known to contain monazite. Monazite occurs in granitic segregations in thorianite-bearing phlogopite pyroxenite of probable metasedimentary origin in the Malagasy Republic, but apparently it does not occur in the pyroxenite (Besairie, 1954, p. 107, 110; Roche and Marchal, 1956, p. 142—144; Behier, 1960, p. 50). Rare occurrences of accessory monazite in diorite are recorded. At one locality in Australia, monazite- bearing diorite is intrusive into slate of the greenschist facies; this monazite contains 6.6 percent of T1102 (table 2). Granodiorite likewise is a minor source despite being widespread in orogenic belts. Only two analyses in table 2 are of monazite from granodiorite; the average amount of thorium oxide in these two analyses is 3.4 percent. 1 The large number of analyses emphasizes the popularity of pegmn- tite for specimen crystals, but they greatly exaggerate the regional geologic role of pegmatite as a host rock for monazite. In many famous pegmatite districts for which an extensive geologic literature exists, it is common to find that for hundreds of dikes described, monazite is reported for only a few. The dominant source rock for monazite in the mag- matic cycle is granite, a term necessarily broadly used here to mean granular rocks composed of quartz, feldspar, and mica. Undoubtedly many occurrences in granodiorite, and possibly some in diorite, are lost in this usage, but nothing less comprehensive is suited to the literature, especially to old reports on mining in regions of weathered rocks. The main kinds of monazite-bearing rock included under granite are biotite quartz monzonite, quartz monzonite, two-mica granite, biotite granite, muscovite granite, cassiterite- bearing granite, and wolframite—bearing granite. Gran- ites that formed during deformation in orogenic belts are far more likely to be monazite-bearing than post- kinematic granites. Synorogenic granites that formed by regional metamorphism in the sillimanite-almandine subfacies or granulite facies are the main monazite- bearing rocks in the magmatic cycle. Synkinematic granites that crystallized under conditions of low—grade regional metamorphism, and postorogenic granites exclusive of the cassiterite—bearing granites, are lean in or devoid of monazite. Cassite-rite-bearing granites and cassiterite-wolframite granites rarely lack mona- zite, and hornblende granites rarely contain monazite, regardless of spatial and temporal relations. Accessory monazite occurs sparingly in quartz porphyry, aplite, and felsite at a few scattered localities but monazite has not been observed as a primary mineral in silicic lava. Volcanic ash beds associated with fresh-water limestone in Victoria, Australia (Coulson, 1924, p. 169— 174), contain minor accessory monazite, but the mona- zite is probably a detrital mineral introduced by stream action at the time the ash was deposited. Good descriptions of monazite in granitic rocks are rare, because the mineral is not seen in most thin sec- tions and in many its presence can be established only by the use of special methods infrequently employed in petrographic work. Heavy-mineral techniques disclose its presence where it makes up no more than 0.00001 percent of the rock (Overstreet, Yates, and Grifiitts, 1963a, table 1). More extensive use of these techniques would doubtless reveal monazite in favorable terrane where it was previously unreported. Such use would tend to redress the disparity between the large number of occurrences reported in tropical, subtropical, and temperate regions, where the mineral is well known as a resistate in weathered rocks, and the very few occur- rences attributed to subarctic and arctic regions, where weathering products were scoured from the rocks by glaciers. An average of 5.1 percent of Th02 was found for the 254 samples of monazite from granitic rocks and for detrital monazite with distributive provinces mainly 22 underlain by granite (table 2). Analyses of 178 of the samples can be ranked according to the probable meta- morphic grade of the wallrocks in which the monazite- bearing granites are emplaced. Practically all the analyses are of monazite from granite in areas where the wallrocks are at the amphibolite facies. The spatial relation is thus established between monazite-bearing granites and metasedimentary rocks of the amphibolite facies, but the temporal relations are not shown by the table. The majority of the 178 analyses are prob- ably of monazite from synorogenic granites. The amount of thorium in monazite from the granites increases as the metamorphic facies of the wallrock increases. Thorium content in monazite from granite related to probable metamorphic facies of wallroclc Th0: Number (percent) 0 analyses Minimum Maximum Average Greenschist facies .................... 1 ........................ 0.47 Epidote—albite—amphlbolite facies _____ 1 ........................ 6.8 Am hibolite facies: wer and middle sublacies ______ 40 2. 2 6. 9 4. 2 Middle and upper subfacies ...... 43 4. l 9. 4 6. 0 Upper subfacies .................. 92 2. 48 13. 66 6. 0 Upper subfacies of amphibolite [soles and granulite facies ................ 1 ........................ 7. 8 A similar relation to metamorphic grade was ob- served for thorium in monazite from metasedimentary rocks. The average amount of thorium in monazite from cassiterite-bearing granites is less than that in monazite from cassiterite-free granites, but this relation may be more apparent than real. Analyses of 62 samples of monazite from cassiterite- and (or) wolframite-bearing granites are given in table 2; these analyses show an average of 3.8 percent of Th02. None of these samples came from granite in granulite facies wallrocks, but 30 samples came from granite in unmetamorphosed sedimentary rocks and greenschist facies metasedi- mentary rocks. The amount of thorium in monazite from cassiterite—bearing granites progressively in- creases as metamorphism of the wallrock increases: Number of Th0: Metamorphic fades of wallrock analyses (percent) Greenschist _____________________________ 30 1. 8 Albite-epidote—amphibolite ________________ 17 4. 2 Amphibolite _____________________________ 15 6. 9 In the cassiterite-bearing granites, monazite has more thorium than in the cassiterite-free granites for equal metamorphic facies of wallrocks. In cassiterite- bearing granites from the amphibolite facies, for which most data are available, an average of 15 analyses of monazite gives 6.9 percent of Th02, whereas an average THE GEOLOGIC OCCURRENCE OF MONAZITE of 175 analyses of monazite from cassiterite-free gran- ites gives 5.6 percent of Th02. The low average tenor of thorium in monazite from the cassiterite—bearing granites, as reported in table 2, results from the fact that a large proportion of the analyses are of monazite from relatively shallow granite. Monazite from 14 samples of unclassified granitic rocks (table 2) contained from 1.99 to 10.05 percent of Th02 and averaged 5.2 percent, an average which is nearly identical to that of all 254 samples of monazite from granite. Monazite in granites generally has more thorium than monazite in the host rocks. As the environment of crystallization of both rocks becomes plutonic, the difference in amount of thorium decreases. Perhaps the amount of thorium converges where anatexis is complete (Winkler and Platen, 1958, p. 91; Walton and others, 1959). Two samples of monazite from aplite (table 2) show a wide range and low average amount of thorium oxide: a range of 0.94—6.2 percent and an average of 3.5 percent. The fact that only two samples come from aplite, whereas 432 samples come from other granites and pegmatites, indicates that monazite is much less common in granitic differentiation products low in volatiles than in the more volatile fractions of the magma. Analyses of thorium in 152 specimens of monazite from pegmatites are given in table 2 according to metamorphic facies of the wallrocks. Although the thorium oxide content of the monazite varies widely, the average is 8 percent; hence, the average monazite from pegmatite contains more thorium than the aver- age monazite from granite. Table 2 shows that few monazite-bearing pegmatites occur in rocks of lower metamorphic facies than the middle subfacies of the amphibolite facies: only 9 out of 152 analyzed samples of monazite are from pegmatites in low-rank meta- morphic terrane. No correlation was found between the amount of thorium in monazite from pegmatite and the metamorphic grade of the wallrock. This lack of correlation is interpreted to indicate that the abundance of thorium in monazite from pegmatites is related to the degree of fractionation of the peg- matite fluids in the local magmatic cycle. Fraction- ation of elements during crystallization of pegmatite has been shown by Murata, Dutra, Costa, and Branco (1958, p. 4, 9—12) to enrich the residual fluids in thorium and to systematically vary the composition of the monazite. Analyses of 42 samples of monazite from other pegmatites in rocks the metamorphic grade of which is not known are given in table 2. The average amount INTRODUCTION , 23 is 7.7 percent of Th02, but the range in the amount is very wide. Monazite-bearing varieties of alkalic rocks are rare, except for syenite pegmatites and carbonatites. Nephe- line syenite in Greenland locally has minor accessory monazite which is reported to be very low in thorium (table 2). Monazite from the carbonatites is also low in thorium; the range shown in table 2 is from O to 4.4 percent of Th0;, the average being 1.8 percent for 14 samples of monazite. The most thorium oxide— rich sample is from Illinois (No. 142, table 2). This monazite is associated with carbonate minerals and fluorite in a cryptovolcanic area. It contains large quantities of yttrium earths, and this composition has been interpreted as showing that it is relatively un- fractionated and primitive (Trace, 1960, p. B64; Murata, and others, 1953, p. 296—297 ; Murata, and others, 1957, p. 148—150). Monazite-bearing volcanic alkalic rocks forming calderas and associated dikes and hydrothermally altered volcanic rocks are eroded to various depths in Africa (Smith, W. C., 1956, p. 189). The youngest and least eroded are in Uganda, and the oldest and most deeply eroded are in the Republic of South Africa. Monazite from carbonatite associated with those rocks tends to be more common and richer in thorium in the deeper parts of the com- plex. In the most deeply eroded carbonatite at Pala- bora in the Republic of South Africa, thorianite is present. Hence, the composition and abundance of monazite in the highly differentiated alkalic rocks is apparently controlled by pressure and temperature, and thorianite appears as a new mineral phase in the deepest part of the complex. Monazite has been reported more commonly from epithermal and mesothermal veins and alteration zones than the number of analyzed samples given in table 2 indicates, but it is noticeably less common in these occurrences than in hypothermal veins. The 20 analy- ses given in table 2 show that the average amount of thorium in monazite increases from 0.2 percent in a sample from an epithermal vein to 3.4 percent in 16 samples from hypothermal veins and alteration zones. Monazite from a vug in a hypothermal vein in Bolivia is devoid of thorium, resembling in this respect the low-thorium monazite in druses and vugs in peg- matites. Most reported vein occurrences of monazite are in cassiterite and wolframite veins. Monazite is also known in quartz veins containing fluorite and molyb- denite, in quartz veins containing hematite, in quartz veins containing carbonate and thorite, and in car- bonate veins containing other thorium minerals and titanium- and niobium-bearing minerals. None of the vein deposits in the magmatic cycle has been a com- mercial source for monazite. Allanite has long been known to weather very readily, and this characteristic accounts for its failure to appear in placers except in Arctic areas. Although its ready weathering invalidates studies based on grain counts of detrital minerals, or minerals in saprolite, as a guide to its distribution (Silver and Grunen- felder, 1957), allanite has been much more frequently observed in thin sections of unweathered rocks than has monazite. Accounts of the two minerals as seen in thin sections show that they are only associated in a restricted range of occurrence in’the magmatic cycle, and allanite is present in many rocks which lack monazite. In general, accessory monazite is absent and accessory allanite is common in plutonic, hypa- byssal, and extrusive mafic rocks and extrusive silicic rocks and their metamorphosed equivalents (Iddings and Cross, 1885, p. 111; Winchell, 1900, p. 206; Wat- son, 1917, p. 466; Smith and others, 1957, p. 367). Allanite is common in shallow granitic rocks where monazite is sparse, and evidence of the replacement of monazite by allanite in these rocks is common (Dietrich, 1961, p. 10). Similar replacements are quite common in granite pegmatite, but locally mona- zite may replace allanite. In alkalic rocks, examples of monazite mantled by allanite are known (Daly, 1903, p. 56). Allanite is an extremely rare mineral in plutonic silicic rocks. From these relations, allanite is interpreted to proxy for monazite as a host for the rare earths and thorium in the mafic rocks and hypa— byssal or extrusive silicic rocks. Apatite, sphene, and the micas also enter this role, but the partition of thorium among them throughout the magmatic cycle has yet to be worked out in detail (Hurley and Fair- bairn, 1957, p. 942; Vainshtein and others, 1956, p. 162—169). CYCLE IN SEDIMENTARY ROCKS The geologic cycle of monazite in sedimentary rocks begins with the freeing of mineral grains from rocks exposed at the earth’s surface and ends with the onset of regional metamorphism of monazite-bearing sedi— ments. The processes in operation are dominated by mechanical agents, which can be rather varied, except at the outset when chemical agents are active. As a result of these mechanical processes, the detrital mona- zite can occur as a sparse accessory mineral or can be concentrated locally in sedimentary rocks. Under unusual conditions such as transport from a small and highly concentrated original source of monazite, the mechanical processes can disperse instead of concen- trate the monazite. 24 THE GEOLOGIC OCCURRENCE OF MONAZITE Monazite is released from the host rock by many forms of mechanical disintegration, but no mechanical process is as effective as chemical weathering. During weathering the soluble fraction of the host rock is removed and the insoluble residue collects as a mantle. Released grains of monazite concentrated near their site of origin constitute eluvial placers. Enrichment of monazite in the residuum may range from about 2 or 3 times to several hundred times its original abundance in the host rock, but generally the enrich- ment is about 10 or 20 times. In deeply weathered areas underlain by monazite—bearing residuum from metamorphic rocks of the amphibolite facies the residuum typically contains 0.5—2 pounds of monazite per cubic yard and rarely may contain 20 pounds of monazite. At many localities where stream placers on weathered rocks have been mined for detrital monazite, the eluvial placers have also been mined, but they have not been commercially important. The main importance of eluvial deposits is as a protore for stream placers. Where streams erode concentrations of monazite in weathered residuum, the stream placers tend to be richer in monazite and the concentrates contain a greater percentage of monazite than other heavy min- erals; in areas where stream placers form over rela— tively unweathered bedrock, the reverse ratio exists. Hence, concentrates from streams in warm humid regions contain a smaller variety of heavy minerals and more monazite than concentrates from streams in more temperate regions. Most of the monazite placers of the world are in the tropical and subtropical regions. Monazite is not completely resistant to weathering. Analyses of monazite from Brazil show that it alters to a dull earthy product through removal of thorium and other components. Under extreme conditions of weathering, monazite also has been found to leach preferentially along some crystal faces and to deposit as authigenic overgrowths on other crystal faces or around other monazite grains (Derby, 1898, p. 190). Loss of monazite from weathering or intrastratal solution in sedimentary rocks, however, is not as great as is indicated by the mineral—persistence data of Pettijohn (1949, p. 486—487), and detrital monazite is known, even in abundance, in ancient Precambrian sedimentary rocks. In areas of profound chemical weathering, monazite is more resistant to solution than hornblende, epidote, garnet, magnetite, and apatite, all of which are indicated by Pettijohn to be more persistent than monazite. Doubtless the vastly greater initial abundance of these minerals over that of mona- zite gives them an appearance of stability and mona— zite an appearance of instability. During fluviatile transport, detrital monazite lags behind detrital quartz, feldspar, and other common minerals and is concentrated with such resistant min- erals as ilmenite, rutile, zircon, and sillimanite. Mona: zite and other heavy minerals tend to settle to the bed of the stream where they are concentrated with the coarser fraction. In deeply weathered areas, most of the stream load is fine sand, silt, and clay; there- fore, the tendency of monazite to settle into thin veneers of coarse clastics results in low tenors among fine-grained sediments. These low-tenor silt and clay deposits generally cover the high-tenor gravels. In the valleys of streams in the Southeastern United States, fluviatile clay contains about 0.1—0.3 pound of monazite per cubic yard, silt contains about 0.7—1.3 pounds of monazite per cubic yard, and gravel has 1.3—2.4 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710—711). Local concentrations in gravel at the heads of small streams may reach as much as 85 pounds of monazite per cubic yard (Mertie, 1953, p. 10). Throughout the world, like tenors have been noted for placers formed under similar geologic conditions. Only under specially favorable economic conditions can such deposits be mined for monazite alone. Stream placers have, how- ever, been the source of commercial monazite (table 1) in the Malagasy Republic, Republic of the Congo (Léopoldville), Republic of South Africa, Federation of Malaya, Korea, Republic of Indonesia, Idaho, North Carolina, and South Carolina. Only those fluviatile deposts where monazite is accompanied by other valuable ores, such as cassiterite in Malaya or gold in Korea, seem profitable for sustained produc- tion. Where monazite-bearing streams empty into lakes or oceans, deposits of heavy minerals tend to form at the mouth of the stream and along downdrift shores. Deltaic placers, particularly where further mechanical concentration has been effected by wind, such as occurs at the mouths of the Nile, have been mined for mul- tiple products. Coastal deposits of great diversity are formed by the constant sorting action of currents, waves, tides, storms, and wind. Present beach deposits are likely to be thin and transient, though locally they may be of very high tenor. After storms some beaches may have surface layers containing asmuch as 90 percent of monazite. Fluctuations of the level of the strand result in the preservation of monazite placers in raised beaches, terraces, lagoonal deposits, or dunes. Fossil monazite placers may also be pre- served on the presently submerged parts of the coast or on the continental shelves (Trumbull and others, 1958, p. 52—58). Beach, terrace, lagoonal, and dune INTRODUCTION deposits are the main source of commercial monazite. The exploitation of these placers in Brazil and India has provided most of the monazite in world commerce (table 1). The richest coastal deposits occur where weathered crystalline rocks of the hinterland are separated from the ocean by a belt of coastal-plain sedimentary rocks, many of Cretaceous or Tertiary age. Prior sedi- mentary concentration in the coastal plain deposits forms a protore from which present beach sands are reworked. Belts of monazite-bearing coastal sedi- mentary formations back up the beach placers in India, the Southeastern United States, and Brazil. Similar belts of monazite—bearing sedimentary rocks are present along the coast of Africa, but they have not been as widely explored as those have in the Americas and India. In some coastal areas the source of monazite in extensive placers is not known. Along the coast of Queensland and New South Wales, an extremely long and complex geomorphic history is indicated for the detrital monazite because the composition of the mona- zite is unlike any in presently exposed source areas. Some beach deposits, like those in New Zealand, have had a complex fluvial-glacial history in which alongshore migration of monazite has continued through several geomorphic cycles. monazite occurrence on the coast of Antarctica seems to have been caused by the ice-rafting of detrital monazite from an area of monazite-bearing plutonic rocks to an area of monazite-free volcanic rocks. Monazite in consolidated sedimentary rocks is for the most part a very minor accessory detrital mineral. Most samples of sedimentary rocks in which accessory detrital monazite has been reported are conglomerate and sandstone. Monazite is very rare in shale and is absent in limestone, except for one locality in Aus- tralia where fresh—water limestone contains detrital monazite. Consolidated sedimentary rocks adjacent to seams of coal in Western Australia contain minor detrital monazite, but the data do not indicate whether it is ' present in coal. Inasmuch as monazite occurs in un— consolidated carbonaceous debris and in metamor- phosed carbonaceous rocks, it probably is present also in coal. Tillite in Australia is locally monazite bearing. Authigenic monazite is unknown in unmetamor-‘ phosed sedimentary rocks, but it has been described as a product of the extreme weathering of quartzite - in Brazil (Derby, 1898, p. 190). Fossil monazite placers are reported from unmeta— morphosed consolidated sedimentary rocks of Cam- 238—813—67—3 At least one . 25 brian and Tertiary age in the Western United States at scattered localities between Canada and Mexico. These placers are composed of thorium-rich monazite presumably deposited by processes similar to those that form placers in the present-day sedimentary cycle. In these areas and in others that are outside of humid and weathered regions, such occurrences might contain commercial sources of monazite. The amount of thorium in monazite from placers varies from place to place in the world and depends upon the kind of crystalline rocks that were the source of the detrital monazite. In general the more plutonic the source rock the more thorium the placer monazite contains. The role of the sedimentary cycle in the thorium content of detrital monazite is, there- fore, one of mechanical blending (Mertie, 1958, p. 5). Mixing during transport characteristically leads to uniform mechanical blends of detrital monazite from diverse sources. As a result, the amount of thorium in samples of monazite from placers varies less than the amount of thorium does in samples of monazite from crystalline rocks. The larger the province from which placer monazite is drawn, the closer individual samples approach a mean, although there is ordinarily a great range in the amount of thorium in individual grains (Richartz, 1961, p. 54—56). ECONOMIC RELATIONS OF THE CYCLES At only a few localities can monazite be mined from deposits formed during the crystalline cycles; these deposits are all in metamorphic rocks. During the early part of the 20th century, a small output of mona- zite was maintained for several years from a monazite- rich zone in biotite gneiss exposed near Shelby, NC. In the 1950’s, large tonnages of monazite were suc- cessfully recovered from a monazite-apatite vein at Steenkampskraal, Republic of South Africa; the vein appears to be a product of metamorphic differentia- tion. Most of the monazite used in commerce has come from Quaternary placer deposits formed in the sedimentary cycle. Beach and dune placers have been the leading commercial source, but lagoonal, terrace, deltaic. deposits, and fluvial placers have also been mined. As of 1962 the discovery of exploitable mona— zite deposits seem more likely among products of the ' sedimentary cycle, particularly fossil placers and beach deposits, than among products of the crystalline cycle. AGE RELATIONS Abumdamce of monazite.——More occurrences of mona- zite in crystalline rocks are reported in Precambrian terrane than in areas underlain by younger crystalline rocks. Apparently, geologic age is an indirect rather 26 than a direct controlling factor. It is indirect because regions occupied by Precambrian rocks contain a greater proportion of high-grade metamorphic rocks and of plutonic igneous rocks than younger parts of the crust, and plutonic rocks are the preferred host rocks of monazite. Precambrian rocks that are not plutonic, or that are otherwise petrologically unfavor- able as a host rock, are as lean in or devoid of monazite as similar but geologically younger rocks. Conversely, petrologically favorable host rocks of Paleozoic or younger age are as rich in accessory monazite as similar rocks of Precambrian age. Thorium content—The average amount of thorium oxide in monazite is shown by the 731 analyses in table 2 to be 6 percent. The amount in monazite of Precambrian age more commonly exceeds the average than the amount does in monazite of Paleozoic or younger age. The greater richness in thorium of Precambrian monazite seems to be a function of the prevalence of plutonic terrane in Precambrian areas instead of an inherent difference in composition di- rectly related to age. Monazite of similar origin, regardless of age, has similar abundance of thorium. Owing to the great half-life of thorium, 1.389><1010 years (Rankama and Sahama, 1950, p. 570), the tenor in thorium of even very old monazite was originally not much greater than it is at present. Although it is not directly related to thorium content, geologic age can be used as an indirect guide to areas most likely to have thorium-rich monazite. MONAZITE LOCALITIES AFRICA Monazite is distributed throughout Africa in a wide variety of geologic environments. Perhaps its com— monest occurrence is as an accessory mineral in Pre- cambrian gneisses, schists, and migmatites, but note- worthy concentrations of monazite have been found in isolated quartz—apatite veins in the Republic of» South Africa and in carbonatite bodies in Northern Rhodesia, Nyasaland, and Kenya. Monazite from the quartz-apatite veins is the major African commercial source for thorium; monazite from the carbonatites is strikingly lacking in thorium and is not an ore for that metal. Other thorium-bearing minerals in the African carbonatites, particularly pyrochlore, have at- tracted commercial attention as ores of thorium, the cerium earths, and niobium. Placers, especially beach placers, have been but little exploited for monazite despite the favorable environment. Placer mining should develop on a far larger scale than is suggested by the intermittent operations of the 1950’s in the THE GEOLOGIC OCCURRENCE OF MONAZITE Nile Delta, Republic of the Congo (Léopoldville), Malagasy Republic, and Nigeria. ALGERIA The massif of homogeneous subporphyritic to por- phyritic very coarse grained biotite granite of prob— able Precambrian age at In Tounine, Algeria, locally contains abundant accessory monazite (Illy and Lau- ney, 1955, p. 112, 123). The massif is shaped like an ellipse, 12.5 miles long and 7.5 miles across, its major axis trending N. 27° W. athwart the foliation of migmatites. In age the granite was said to compare with the younger granites of Nigeria. Monazite is common in the western and northwestern part of the massif where it is associated with zircon and pink garnet. Concentrates from small alluvial placers in the western part of the In Tounine massif contain abun- dant monazite, ilmenite, wolframite, and cassiterite, and less abundant topaz, some zircon, and sparse scheelite, fluorite, garnet, and epidote (Illy and Lau- ney, 1955, p. 125—126) . CENTRAL AFRICAN REPUBLIC Monazite was found as early as 1914 in the Central African Republic in diamond-bearing concentrates panned from alluvium in the Cheniandaka River, a tributary of the Ngrissi River (Brustier, 1934, p. 435). Accompanying minerals are rutile, zircon, tourmaline, kyanite, and garnet. The Cheniandaka crosses the contact between muscovite granite and an interlayered sequence of quartz-muscovite schist, graphite schist, micaceous quartzite, and graphitic quartzite. Acces- sory minerals in the schists are zircon, tourmaline, garnet, rutile, kyanite, and very fine grained lemon- yellow monazite. The monazite contains about 6 per- cent ThOz. Although diamonds were not found in concentrates from the schist, Brustier surmised that diamonds formed from high—temperature contact meta- morphism of the graphitic schist where the schist was intruded by the granite. Monazite was not found in the granite. * Monazite sand said to have 7 percent of Th02 was reported to occur at J akundu (Marble, 1949b, p. 90). Monazite-bearing pegmatites occur in migmatite to the south of Ippy in the Central African Republic (Bessoles, 1955, p. 22). Enclosed in the migmatites are layers of quartzite and mica schist, and associated with these rocks are two-mica gneiss, hornblende—bio- tite gneiss, amphibolite, and biotite—muscovite granite. The rocks are rich in microcline. Doubtless, monazite occurs in rocks other than the pegmatites. AFRICA ETHIOPIA Monazite occurs in the alluvium of the Dacata River at Errer in Ethiopia (Usoni, 1952, p. 70, pl. 5). It is also present at Quoscerscer about 12 miles east of Harrar. FEDERATION OF RHODESIA AND NYASALAND CRYSTALLINE ROCKS Monazite was discovered in 1949 in concentrates from Changwena Stream which heads in the Irumi Hills in the Mkushi district of the Central Province of the Federation of Rhodesia and Nyasaland (O’Brien, 1958, p. 26; Cahen and others, 1953, p. 52; Colonial Geology and Mineral Resources, 1954, p. 291). Here the Irumi Hills are underlain by Muva quartzite and form part of the divide along the border with the Republic of the Congo (Léopoldville). The concen- trates contain only 3—4 percent of monazite, and the tenor of the sediments in the valley of the Changwena is too low to support any form of placer mining. The locality has, however, considerable interest as a place where the geologic cycle of monazite, particu- larly the relation of the abundance of thorium oxide in the monazite to the grade of metamorphism of the host rock. The sources of the detrital monazite in Changwena Stream are fossil placers in quartzite and conglomerate of the Muva System. Interbedded with the quartzite are thin bands of pelitic sedimentary rocks variously metamorphosed from the lowest sub— facies of the greenschist facies to the intermediate subfacies of the amphibolite facies. Intrusive rocks do not occur in the area. Several monazite-bearing fossil placers have been found in the quartzite and conglomerate. One of the largest and best exposed is a ledge as much as 18 inches thick and 0.25 mile long which crops out at the lip of the upstream cataract of Changwena Falls. Another well—exposed monazite-bearing fossil placer forms Mumpu moun- tain at the northeastern end of the Irumi Hills. Seven samples of the monazite—bearing rocks were taken by O’Brien (1958, p. 28) from four localities. The samples were crushed and panned. Monazite and zircon occurred as well-rounded grains, but the ilmen- ite and other heavy minerals were present in euhedral form or as fragments of euhedral grains. O’Brien , interpreted the round grains of monazite and zircon to be relict detrital particles preserving water-worn forms and the other grains to be the recrystallized products of the metamorphism which affected the Muva quartzite and conglomerate. Early reports on the composition of the monazite from Changwena Stream indicated that the monazite 27 contained 9 percent of 6Th02 (O’Brien, 1958, p. 26). This estimate was supported by the following chemical analysis of alluvial monazite from the Irumi Hills made by the Chemical Research Laboratory, Tedding— ton, England (Holmes, Arthur, 1954, p. 613): Percent U303 ______________________________________ 0. 10 Th02 ______________________________________ 9. 29 Pb ________________________________________ . 58 A sample of monazite from the Muva quartzite, however, was analyzed by the Department of Scien- tific and Industrial Research, Teddington, England, (O’Brien, 1958, p. 28) and was found to have the following thorium oxide content: Percent U303 ______________________________________ 0. 08 ThOz ______________________________________ 3. 07 Pb ________________________________________ . 19 O’Brien postulated that the original source of the detrital monazite in the fossil placers in the Muva quartzite might be granite and that the source could have been some hundreds of miles away. The source has not been found. Although the amount of thorium oxide in the mona- zite from the quartzite is somewhat lower than that ordinarily associated with monazite from granite, such tenors are known from the upper parts of large batholiths, such as that in Idaho, U.S.A., and from the shallow tin-bearing granites of Indonesia. Ero- sion since Muva time might well have stripped away the parts of the granitic bodies that originally yielded monazite of lower thorium oxide content, and might have exposed rocks with accessory monazite having almost twice as much thorium oxide. It is possible that the present low percentage of thorium oxide in the monazite from the quartzite may have resulted from reduction of an originally greater amount by the regional metamorphism that acted on the Muva System; this metamorphism may have caused the recrystallization of ilmenite and other associated heavy minerals. Abundances of thorium oxide of about 3 percent are very commonly associ- ated with monazite from metamorphic rocks of the albite-epidote-amphibolite facies. If the original abun- dance of thorium oxide was more than 3 percent (the determination of about 9 percent of ThOz in monazite from streams in the Irumi Hills may be the tenor of the least altered monazite in the region) and if the composition of the monazite changed as the grade of metamorphism changed, then 3 percent of Th02 might be expected in monazite from Muva quartzite meta- morphosed to the albite—epidote—amphibolite facies. Inasmuch as the quartzite has been affected by a wide 28 THE GEOLOGIC OCCURRENCE OF MONAZITE range of metamorphic grades (O’Brien, 1958, p. 27), the monazite in it might be expected to exhibit a variation in its thorium oxide content, and the varia- tion should relate to the metamorphic grade. It would be interesting to know which rocks contain monazite having 9 percent of Th02 and which contain mona- zite having 3 percent of Th0;;. Original variation in the composition of the detrital monazite in the fossil placers is unlikely to have been very large, because the processes of erosion, transpor- tation, and deposition are efficient blenders. Placer monazite is usually similar in bulk composition throughout the placer district, despite possible wide variation in the amount of thorium oxide in individual grains; therefore, it is reasonable to assume that changes in the composition of the monazite in differ- ent parts of an extensive fossil placer are produced by conditions operating on the mineral after the placer was formed. Absence of intrusive rocks in the Irumi Hills area further adds to the excellence of the area as a place in which to study the behavior of monazite during metamorphism. Peculiar green cryptocrystalline monazite forms minute spherulites in thin cracks in carbonate min- erals or in silicified carbonatite in the volcanic. plug that forms the prominent Nkumbwa Hill 15 miles east of Isoka (Reeve and Deans, 1954, p. 271—277). The carbonatite plug is composed of dolomite and either ankerite or siderite. The carbonatite contains apatite and other phosphate minerals including mona— zite and accessory pyrochlore and sellaite. Carbona- tite forming the summit of Nkumbwa is completely silicified. Around the base of the plug are sparse outcrops of biotite gneiss, hornblende gneiss, and gran— ite. Monazite from Nkumbwa is practically non— radioactive; therefore, it contains virtually no thorium. Four monazite-bearing carbonatite ring complexes lie along an east-southeast-trending arc in the valley of the Luangwa River near the mouth of the Rufunsa River in the Central Province (Bailey, 1958, p. 35—37) . The most southerly of the carbonatite bodies forms the hill called Chasweta. From south to north the other three carbonatite complexes are known as Mwambuto Hills, Nachomba Hill, and Kaluwe. They lie in a downfaulted block of arenaceous sedimentary rocks. Chasweta is the main vent of an eroded volcano having varied and complex lithologic and intrusive relations (Bailey, 1958, p. 38). Calcareous pyroclastic rocks fill the main vent, and a variety of carbonate dikes, crushed potassium-feldspar rock, fine to coarse agglomerate containing variable amounts of sandstone inclusions, and silicified and limonitized carbonatite are present. Concentric flow banding is locally well formed in the carbonatite core of the vent. The chief accessory minerals are barite, iron oxides, pyrochlore, very fine grained monazite, and rutile. Mwambuto Hills are 7 miles west-northwest of Chasweta (Bailey, 1958, p. 39). They form an iso- lated ring 3 miles across that encloses a circular de- pression 1 mile in diameter. The structural feature has been recognized as a volcanic neck. Nachomba Hill is 9 miles northwest of Mwambuto Hills. It is a circular peak 0.5 mile in diameter consisting of silicified, limonitized, and phosphatized carbonatite that rises in the northern part of a circular depression about 3 miles in diameter. Kaluwe is a hill of car- bonatite 5 miles north of Nachomba Hill. Little work has been done there, and its geology is not well known. Monazite is probably present in all fourcarbonatite bodies, but was only mentioned by Bailey in the de- scription of Chasweta. Pyrochlore is present in each of the carbonatite bodies. The abundance of thorium in the monazite was not indicated. Monazite is disseminated in quartz-feldspar granu- lite near Dedza, in garnetiferous biotite—quartz gneiss near Masamba village, and in epidotized bands of gneiss near Kasupe north of Zomba (McNaughton, 1958a, p. 26; 1959). The Zomba locality has been known since 1911 as the source of fluvial concentrates having about 15 percent of monazite (Dunstan, W. R., 1911, p. 17), but minable deposits of monazite have not been found. Aplite dikes on Lungu Hills contain monazite and are regarded as one of the possible sources of the detrital monazite found in placers on the shore of Monkey Bay, Lake Nyasa (McNaughton, 1958a, p. 27). Monazite-bearing soil of unspecified origin occurs 3 miles west of Balaka (McNaughton, 1959). Low-thorium oxide monazite is an accessory mineral in carbonatite rocks of volcanic origin in the Chilwa series in Nyasaland (Thomson, 1952a; Mining World, 1954; Lombard, 1955, p. 313; Cooper, W. G. G., 1957 ; p. 21). The most noteworthy occurrence of monazite is in the carbonatite complex at Kangakande Hill (Kangankunde Hill, Kangkangunde Hill) in the Sen- zani area of the Zomba district of Nyasaland (Gar? son, 1958a, p. 7-10; Smith, W. C., 1956, p. 195). At the Kangakande vent the Precambrian basement com- plex is fenitized and is separated from the central plug of the vent by contact breccia and feldspathized agglomerate. The agglomerate and fenite are car- \ AFRICA bonatized over an area about 2,100 feet long by 1,200 feet wide. During the first stage of the carbonatiza- tion, the rocks were soaked with strontianite, ankerite, and siderite, and along with these minerals were intro- duced small amounts of pyrochlore and barite. As carbonatization increased, monazite, florencite, syn- chysite, bastnaesite, pyrite, sphalerite, and galena were introduced. Monazite and the other rare-earth min- erals commonly form spherulitic structures in the carbonatite. Much of the inner northern part of the carbonatite complex, an area about 750 by 600 feet in size, contains 4—5 percent of green fine—grained monazite. An analysis by the Mineral Resources Division of the Federation of Rhodesia and Nyasaland disclosed that this monazite contained the following amount of thorium oxide (Garson, 1958a, p. 9): Percent 06203 _____________________________________ 32. 5 La203 (group) ______________________________ 35. 6 Th02 ______________________________________ . 4 P205 ______________________________________ 30. 9 Insoluble in H2804 __________________________ . 4 Total _______________________________ 99. 8 The amount of monazite in the carbonatite is throught by Garson to remain fairly constant with depth; thus, a reserve that has many millions of tons of ore containing 4—5 percent of monazite is available. Fine grinding is needed to separate the monazite from the other constituents; however, as late as 1958, methods for the final separation of the finely ground monazite from strontianite had not been perfected. An iron-stained feldspathic dike containing several percent of disseminated fine—grained light-brown mon- azite and a few percent of intergrown bastnaesite and parisite is exposed 2.5 miles to the northwest of the northern part of Kangakande Hill (Garson, 1958b, p. 16). This monazite has 2.2 percent of T1102. Thorium—poor monazite has also been found in the carbonatite bodies at Shirwa Island (Chilwa Island) and Tundulu Hill (Davidson, 1956b, p. 208). Monazite is an accessory mineral in the cassiterite- bearing pegmatite dikes at the Jack tin claims north of Salisbury, Southern Rhodesia (Holmes, Arthur, 1954, p. 613; Colonial Geology and Mineral Resources, 1954, p. 291; Holmes and Cahen, 1955, p. 26; Ahrens, 1955, p. 295). The dikes also contain lithium-, beryllium—, and tantalum-bearing minerals. Monazite from these dikes contains 9.36 percent Th and 0.19 percent U (Holmes, Arthur, 1954, p. 613). It is also an accessory mineral in pegmatite dikes at the tin and tantalum field in the Bikita district (Barlow, 29 1934, p. 42; 1955, map; Cahen and others, 1953, p. 52; Holmes, Arthur, 1954, p. 613; Colonial Geology and Mineral Resources, 1954, p. 291; Holmes and Cahen, 1955, p. 26; Ahrens, 1955, p. 295). The principal monazite locality is about 25 miles northwest of Bikita. Monazite from a tantalite-bearing pegmatite at the Ebonite tantalum claims, about 4 miles southwest of the main Bikita tin field, contains 2.72 percent of ThOZ and 0.087 percent of U308 (Holmes, Arthur, 1954, p. 613). FLUVIAL DEPOSITS Monazite has been said to be present in most rivers in Northern Rhodesia that drain from granitic ter— rane. Thirty-six concentrates panned by Davidson (1953, p. 75) from gold placers near the border with the Republic of the Congo (Léopoldville) contained from 3 to 10 percent of thorium oxide-rich monazite; however, in only a few places does the tenor of the fluvial sediments reach 2 pounds of monazite to the cubic yard, and no deposit suitable for dredging had been discovered by 1955 (Davidson, 1956b, p. 208). Occurrences of detrital monazite in the streams in Nyasaland were widely noted as early as 1906 (Dun- stan, W. R., 1908, p. 10—35), but none proved to be an economic deposit of the mineral. Since that time several of the occurrences of detrital monazite have been traced to their bedrock sources (Alexander, J. B., 1939, p. 20—21; Cooper W. G. G., 1957, p. 21). Monazite-bearing concentrates were reported by W. R. Dunstan (1908, p. 15—35; 1909, p. 36—38; 1911, p. 9—17) at several localities. M onazite-bearing streams in N yasaland [Sourcesz Dunstan (1908; 1909; 1911). Trace, less than 1 percent; present, between 1 and 2 percent] Monazite Stream (percent) Ndeka River, Ncheu ______________________________ 0. 4 Kungus River, tributary to the Livulezi River _______ . 07 North and south branches of the Lisungwe River _____ Trace Three localities on Nyankokola River ________________ Trace Chikukala River ___________________________________ 1. 5 Tributary to Ngena River near Tambani ____________ Trace Dwali River near Msen ____________________________ Trace Mwanza River near Myowe Hill ____________________ Trace Nankande River __________________________________ . 5 Ngoma River _____________________________________ 1. 5 Nyamadzere River ________________________________ Trace Nyangundi River _________________________________ Trace Lifuluni River, tributary to the Ruo River __________ Trace Nswadzi River ___________________________________ Trace Zanseu stream near Lungudzi ______________________ Trace Stream opposite Dowa Boma on the Lingadzi River--- Trace Makeye River ____________________________________ Present Songwe River near Msikuora _______________________ Present Stream below Milonde’s village _____________________ Present Kaseya River ____________________________________ Present 30 M onazite-bearing streams in Nyasaland——Continued [Sourcesz Dunstan (1908; 1909; 1911). Trace, less thanl percent; present, between 1 and 2 percent] Monazite Stream (percent) Lufira River 2 miles up the gorge ___________________ Present Lufira River near Mweniweyma ____________________ Present Lufira River near Changoroma Hill _________________ Present Few miles from source of River Chungu _____________ Present Sere River near Sere village ________________________ Present Ziwa stream near Muoma Hill ______________________ Present Near Chemenyonga village and Muoma Hill _________ Present Mwesia River at Mpata ___________________________ Present Vungwu River near Mwenemguwe __________________ Present Head of Fuliwa River _____________________________ Present Kaswenta stream near Majimpula village, south-central N yika _________________________________________ Present Katise stream near Mapangania village, south-central Nyika _________________________________________ 10 Luviri River near Katemba village __________________ Present Michowo stream near Ngaloto village, northwestern Nyika _________________________________________ Present Rumpi River near mouth __________________________ Present North of Njowi village, Henga valley ________________ Present Nhuju stream, Henga valley _______________________ Present Stream by Njowi village ___________________________ Present Lufiri River near Salimu village ____________________ 3 Liwasi River northeast of Kulumani village __________ 13 Chisita stream, tributary to Dwangwa River _________ 4. 5 Dwangwa River near Litala village _________________ 4. 5 Dwangwa River near Kapyanga village ______________ 4 Dwangwa River near Tambala village _______________ 3 Small stream just below Zomba village on the Dwangwa River _________________________________________ 15 Mostly the monazite is present in the concentrate in abundances of 1—5 percent. In a few places, it reaches 15 percent of the concentrate. Chief associated min- erals are ilmenite, magnetite, garnet, hornblende, ru— tile, and zircon and less abundant epidote, sillimanite, tourmaline, and kyanite, and sporadic apatite, pyrox— ene, spinel, titanite, andalusite, and gold. Streams in the Tambani region mentioned by Dunstan were later reported to be the source of 39 monazite-bearing con— centrates out of 40 concentrates examined (David- son, 1956b, p. 208; 1959a, p. 179). Thorite, pyrochlore, and betafite were observed in 25 of the concentrates, and uranothorite was found in 11. According to Davidson (1956b, p. 208), the source of this assem- blage of heavy detrital minerals is syenite and other crystalline rocks. Detrital monazite of unknown origin from a stream at Namalundo Hill near Chiromo (Dixey, 1930, p. 11) in the southernmost part of Nyasaland was analyzed by Johnstone (1914, p. 57; Imp. Inst. [London], 1914a, p. 58) and found to have the following composition: Percent Percent 0e20, ________________ 32. 52 SiOz _________________ 1. 66 La203 (group) _________ 26. 91 A1203 ________________ . 20 Y203 (group) _________ 1. 51 Fe203 ________________ 1. 10 Th02 ________________ 7. 10 CaO _________________ . 32 P205 _________________ 28. 16 Loss on ignition _______ . 25 THE GEOLOGIC OCCURRENCE OF MONAZITE Concentrates from streams at 70 localities in areas underlain by crystalline rocks in the southern part of Nyasaland were reported by Dixey (1930, p. 11) to contain monazite. In order of relative abundance the minerals in the concentrates were ilmenite, mag- netite, garnet, zircon, apatite, sphene, epidote, rutile, kyanite, sillimanite, spinel, tourmaline, staurolite, anda- lusite, and monazite. Alluvium from the Mwanza River was shown to be monazite-bearing, thereby con- firming earlier identification by W. R. Dunstan (1908, p. 26). Monazite was found in alluvium of the Tan- gadzi River. A few grains of monazite have been noted in a con- centrate made from stream sediments in the Njakwa Gorge area of the Mzimba district, N yasaland (Alex- ander, J. B., 1939, p. 20—21). Most of the concentrate consisted of magnetite, hematite, garnet, and zircon, and small amounts of epidote, hornblende, and pyrox- ene. In the Njakwa area the rocks are low-rank schists intruded by porphyritic orthoclase-hornblende- biotite granite. Sparse monazite occurs with low—titanium oxide il- menite near Port Herald in the alluvium of the Shire River, the outlet of the Lake Nyasa (Dixey, 1926, p. 210; 1930, p. 11; McNaughton, 1958a, p. 27). Only a. small volume of alluvium was said to be present (Marble, 1949b, p. 91). LACUSTRINE PLACERS Monazite placers were discovered in the beaches at Monkey Bay on Lake N yasa in 1955 (Mining World, 1957a; McNaughton, 1958a, p. 27 ). After this initial discovery, other lacustrine monazite placers were found toward the north end of Lake Nyasa and on the east shore of Lake Nyasa opposite Monkey Bay (McNaughton, 1958a, p. 27). Other alluvial deposits were on the Palombe plain between Lake Shirwa and Mlanje Peak (p. 27). As previously mentioned, one of the sources of the detrital monazite at Monkey Bay has been said to be aplite dikes at Lungu Hill (p. 27), but as there are many varieties of bedrock in the drainage basin of Lake Nyasa, the detrital monazite probably has sev- eral sources. This monazite was stated to contain 6.2 percent of Th02 (South African Mining and Eng. Jour., 1956a). Although active prospecting of the Lake Nyasa beaches was under way in 1957, no de- posits had been opened for production by 1958 (Mo- Naughton, 1958b, p. 28). GHANA Monazite has been found in stream gravels in many parts of Ghana, but ordinarily it is one of the less common minerals. Kitson and Felton (1930, p. 13—48) AFRICA discussed the mineralogy Of 639 concentrates selected from a collection of 15,500 concentrates panned from alluvium, saprolite, and crushed rock by members of the Gold Coast Geological Survey (Junner, 1959, p. 1320). The report showed some interesting mineral associations in the 91 concentrates that are monazite bearing. The mineralogy of the monazite—bearing con— centrates is tabulated in table 3, together with a sum— mary of the geographic distribution of monazite, and the kinds of rocks represented by the concentrates. In five concentrates, monazite is the most abundant heavy mineral, and in six it is the 2d most abundant; gener- 31 ally, it is the 5th to 11th mineral in order of abundance. Where monazite is not the most abundant, it is pre- ceded by one or more of the following: Zircon, mag- netite, ilmenite, rutile, sillimanite, kyanite, staurolite, garnet, epidote, and tourmaline. Magnetite, sillimanite, andalusite, staurolite, garnet, and sphene occur more frequently in monazite-bearing concentrates than in monazite-free concentrates (table 4). The increase in frequency of these minerals is related to the association of the monazite with granitic rocks and metamorphosed sandstone, graywacke, and shale. Kitson and Felton (1930, p. 9) showed the TABLE 3.——Relat’£ve abundance of minerals associated with monazite in concentrates from Ghana [After Kitson and Felton (1930, p. 5—48)] Birim Ashanti Akim Birrimian Granite— ' _ . system— dikes and Birrimian system containing dikes Voltalan Birnmaan granite Voitaian sand system(?) and dikes sand Gil-HOLLOW Kyanite . _ _ Andalusite _ Stanrolite . . Garnet ..... Epidote _ _ . . Amphibole. Spinel _____ <0 Accra Granite and gneiss containing dikes Cape Coast Birrimian system containing granite, gneiss, and dikes Saltpond Volta River Tarkwa Granite and gneiss— dikes Tarkwaian Quartz system(?) vein in pegmatite Granite and gneiss containing dikes Monazite __________________ Ilmenite _________ Rutile ___________ Sphene Tourmaline _______________ H hm N) snot-IUIO Winneba Western Akim Mampong Snnyani Eastern Gonja Birrimian Granite and system— dikes Tarkwaian systemCI) gneiss containing ikes Birrinn'an system containing granite and dikes Voltaian Granite. gneiss, Voltaian sand sand dikes and Voltaian sand ll Magnetite_- _______ Ilmenite . _ _ Sillimanite. Kyanite _ - Andalusite Stanrolite . Garnet. _ Epidote._ _ Amphibole Spinei _ _ Sphene . __ _ 05“qu @mhoqgfl 32 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 3.—Relative abundance of minerals associated with monazite ’L'n concentrates from Ghana—Continued Kete Krachi Western Dagomba Ahafo-Goasa Obuasi Wenchi Birrimian Kusasi Kumasi Voltaian sand Birrimian system and granite, gneiss, and dikes system and Voltaian sand Quartz Birrimian system and granite, vein gneiss, and dikes H rowan-so wNQFQ l I l I l I I I 11 ________ 3 4 N) I E I I I I WWI-I Sillimvmitn Kyanite _ ___________ issue: #6301 hNQM I I I I I I I I I I mason-4x! surname: (1)02»th Andalusite ........ Staurolite ......... Garnet ____________ Epidote ___________ Amphibole ________ Spine] __________ Sphene . ________ ._ Tourmaline _______________ Birrimian system and granite, gneiss, and dikes—Continued KumasI—Continued Monazite __________________ Zircon _______ Magnetite. __ Ilmenite _ _ _ _ Rutile ______ Sillimanite. _ Kyanite _ _ _ _ Andalusite. _ Staurolite _ _ _ I.‘ \IWWD-‘N consan— \IN 0.50360! H H H Kumasi—Continued Birtimian system and granite, gneiss, and dikes—Continued Birrimian system and granite, graeiss, and dikes and Voltaian san 63‘!on TABLE 4.—Frequency of mineral occurrence in concentrates from Ghana [Recalculated from Kitson and Felton (1930, p. 5—48)] Percent of concentrate! containing minera 91 monuzite— 648 monazite- bearing free concentrates concentrates Zircon __________________________ 99 94 Magnetite ______________________ 77 49 Ilmenite ________________________ 9 1 9 1 Rutile __________________________ 69 68 Sillimanite ______________________ 25 3 Kyanite ________________________ 46 37 Andalusite ______________________ 27 8 Staurolite _______________________ 74 49 Garnet _________________________ 65 30 Epidote ________________________ 44 37 Amphibole ______________________ 21 24 _, Spinel __________________________ 1 4 2 1 Sphene _________________________ 9 2 Tourmaline _____________________ 72 7 4 sillimanite, andalusite, staurolite, and garnet to be com- mon detrital minerals in streams draining metamor- phosed sedimentary rocks, and they reported the Sphene to come from granite and pegmatite. Spine] and amphibole, which occur less commonly in the monazite-bearing concentrates than in the monazite- free concentrates, are indicated as coming from mafic and intermediate rocks. Forty-four monazite-bearing concentrates came from areas in which metamorphic rocks of the Birrimian system, associated granitic rocks, and possibly older Precambrian gneisses are exposed. The Birrimian system is a geosynclinal sequence which consists of an older suite of phyllite, schist, graywacke, and tufi', and a younger suite of lavas and mi]? containing subordi— nate phyllite and graywacke (Junner, 1938, p. 4). AFRICA Locally the Birrimian rocks reach the metamorphic rank of staurolite-garnet schist and kyanite-staurolite schist (Kitson and Felton, 1930, p. 6). Precambrian rocks older than the Birrimian system comprise horn- blende and biotite gneisses, migmatites, granulites, and schists, some of which are garnet-iferous. The Bir- rimian and older Precambrian rocks are intruded by large masses of foliated granite and granodiorite and small ones of massive soda—rich granite, granodiorite, and porphyry. Both groups of granitic rocks are Precambrian in age and are older than the overlying Tarkwaian sedimentary rocks. The common association of kyanite, staurolite, garnet, andalusite, and epidote in monazite-bearing concentrates from regions underlain by the Birrimian system attests that the Birrimian rocks are metamor- phosed to the albite-epidote—emphibolite facies and to the staurolite-kyanite subfacies (Turner, F. J ., 1948, p. 76). Sillimanite schists and gneisses of the upper amphibolite and granulite facies seem to have formed locally in pre-Birrimian rocks and sillimanite schists of the amphibolite facies may have formed in the Bir- rimian. rocks. Of the 639 concentrates reviewed by Kitson and Felton (1930, p. 13—48), 40 contain silli— manite, and 23 of these 40 are monazite bearing. Of the 91 concentrates that Kitson and Felton reported monazite bearing, 41 are from samples taken in areas where the Voltaian sand, a pre—middle Devonian sequence of shale, mudstone, and sandstone, is exposed with granites and the metamorphosed sedi— mentary rocks of the Precambrian Birrimian system. Voltaian rocks cover 45 percent of the surface of Ghana. They are horizontal or gently inclined and are practically devoid of intrusive rocks and veins (Junner, 1938, p. 2—5). From the descriptions of the 41 concentrates, the relative roles of the Voltaian sedi- ments and the Birrimian rocks as sources for the monazite cannot be determined. Mineralogical simi- larities between monazite—bearing concentrates panned from areas underlain by rocks of the Birrimian system and monazite-bearing concentrates derived from areas in which both Voltaian sands and Birrimian rocks are exposed suggest a dominant role for the Birrimian rocks and their associated granites. Four monazite-bearing concentrates came from areas questionably underlain by the Tarkwaian system, a sequence of Precambrian rocks younger than the Bir— rimian system. The Tarkwaian rocks consist of a weakly metamorphosed basal conglomerate succeeded upward by quartzite and conglomerate, phyllite, and sandstone. Large sills of altered gabbro and small sills and dikes of granite and diabase intrude the Tark— waian system (Junner, 1938, p. 4—5). Epidote, andalu- 238—813—67—4 ' 1924a, 33 site, and staurolite occur in these concentrates, but sillimanite is absent. Of the 91 monazite-bearing concentrates, 2 came from quartz veins in pegmatite and granite. The dis- tribution of the 91 monazite-bearing concentrates shows that in Ghana, monazite occurs locally in Precambrian migmatite, granulite, gneiss, and schist; these host rocks are of uppermost amphibolite facies and granu- lite facies (the pre-Birrimian rocks). Monazite is locally present in Birrimian schists that are of middle and lower amphibolite facies and in albite—epidote- amphibolite facies. This mineral is present in granite and pegmatite and in quartz veins in the Birrimian and pre-Birrimian rocks. It is possibly present in the slightly metamorphosed and. feebly intruded younger Precambrian sedimentary rocks of the Tarkwaian system. Monazite may be an accessory mineral in the unmetamorphosed and virtually uninjected sedi- mentary rocks of pre—middle Devonian age known as the Voltaian sands. F inc-grained muscovite granite near Asamang in the basin of the Pra River is the source of small amounts of monazite found in the stream gravels (Kitson, p. 6). Accompanying the monazite are ilmenite, leucoxene, magnetite, hematite, limonite pseudomorphous after pyrite, epidote, tourmaline, zircon, garnet, and a few flakes of gold. Near Foso, biotite schist crops out in the Nsuisen Su, and concentrates from the stream consist of kyanite, epidote, monazite( ?), zircon, staurolite, garnet, rutile, ilmenite, magnetite, hematite, and a little gold (Kitson, 1924a, p. 7). Other streams in the same area also con- tain a little monazite, some of it doubtfully identified (Kitson, 1929a, p. 8). Gravel in the Sirekuma Su near Apisim was the source of a staurolite—rich concentrate containing mona- zite(?), zircon, epidote, garnet, ilmenite, magnetite, and gold (Kitson, 1924a, p. 16). The stream flows on an area of biotite granite in which there are inclusions of metasedimentary rocks. Decomposed biotite granite in the bank of the Tain River contains monazite, as does the streambed (Kit- son, 1924a, p. 48). Concentrates from stream sediments in the area between Kumasi and Chichiweri (Chichiwerri) and in the vicinity of Abofuo contain ilmenite, rutile, magnet— ite, hematite, garnet, zircon, staurolite, epidote, kyanite, monazite, schorl, and columbite and a little cassiterite and gold (Kitson, 1924b, p. 8) . Underlying the area is foliated biotite-muscovite granite intruded by dikes of muscovite pegmatite. 34 Sand in the Black Volta River near Saru was the source of concentrates that consisted of abundant rutile and some zircon, garnet, staurolite, kyanite, and epi- dote, a few specks of gold, and possible monazite (Kitson, 1924b, p. 21). Porphyritic biotite granite exposed near Daboase intruded fine-grained biotite gneiss and hornblende- garnet gneiss, but it produced only slight metamor- phism in the intruded rocks. Thin sections of the granite disclose that it contains monazite and allanite (Kitson, 1929b, p. 9). A panned concentrate from a biotite pegmatite dike in biotite schist exposed 0.8 mile southeast of Nakwaby (Nakwabi) contained zircon, rutile, spinel( ?), mona- zite( ?)’, axinite( ?), cassiterite( ?), kyanite, magnetite, and schorl (Kitson, 1927, p. 15). Small concentrates that were rich in monazite were obtained from weathered debris of granite and pegma- tite in the vicinity of Chimera (Kitson, 1927, p. 43). Monazite is common in the gold placers in Ghana (Junner, 1938, p. 9). Diamond placers in Ghana locally contain very small amounts of monazite. In their approximate order of abundance, the main heavy minerals in the placers are staurolite, ilmenite, limonite, rutile, and tourmaline. Generally present but sparse are zircon, magnetite, hematite, leucoxene, kyanite, andalusite, and pyrite. The scarce minerals are actinolite and tremo- lite, anthophyllite, sphene, epidote, anatase, monazite, apatite, chrysoberyl, corundum, gorceixite, xenotime, sillimanite, beryl, brookite, and cassiterite (Junner, 1943, p. 21). Except for a few places the monazite- bearing diamond placers are confined to streams in the vicinity of the granite near Manso, Supongo, and Osenasi. Diamond placers in the Bershea Su, a small stream 2 miles south of Kader, also contain monazite (Junner, 1935, p. 9). Placer monazite from Kodiabe (Kotabebi), analyzed by E. H. Beard of the Imperial Institute in London (Junner and James, 1947 , p. 54), contains 6.5 percent of Th02 and 61.47 percent of REOz. Chemical weathering in parts of Ghana extends to great depths in the wet-forest regions depth of weathering may be as much as 200 feet, and the decom- posed rocks provide a ready supply of chemically resistant heavy minerals to the rivers that empty into the Gulf of Guinea. The rivers, in turn, might be expected to discharge monazite—bearing black sands into the gulf, where shore currents along the beach might further sort the heavy minerals; however, the concentrates from coastal sands described by Kitson and Felton (1930, p. 13) were devoid of monazite. Monazite has not been mined in Ghana. THE GEOLOGIC OCCURRENCE OF MONAZITE- KENYA Monazite, beryl, and rutile locally occur as accessory minerals in pegmatite dikes in the gneiss, granulite, schist, and orthogneiss of the Loldaika Mountains— Ngare N dare area (Murray-Hughes, 1933, p. 5; Hitchen, 1937, p. 90). Monazite was found in the early 1950’s in carbonatite intrusives at Mrima Hill near the border with Tangan- yika about 40 miles south of Mombasa. The carbona- tite intrusives are exposed in an area of Permian and Triassic sedimentary rocks and apparently intrude them. The monazite contains less than 1 percent of Th02 (Pulfrey, 1947, p. 281—282; Davidson, 1956a, p. 206). Monazite is a minor constituent of the black sands at the mouths of the Galana (Athi) River and the Tana River, which are streams that empty into the Indian Ocean (Pulfrey, 1947, p. 297 ; 1954, p. 25) ; it has been found on Patta Island (Hintze, 1922, p. 344). Mona- zite placers are likely to be found in streams that drain sillimanite gneisses and granulites of the Precambrian basement in the central and western part of the country and also in sedimentary rock of Jurassic to Recent age that overlie the gneisses in the eastern part of the colony (Pulfrey, 1947, p. 279, map). LIBERIA Monazite was said to occur in Liberia, but details were not given (Wallis, 1907). MALAGASY REPUBLIC CRYSTALLINE ROCKS, ELUVIUM, AND FLUVIAL SEDIMENTS The distribution of monazite in the crystalline rocks, eluvium, and fluvial sediments of the Malagasy Repub- lic was reviewed by Lacroix (1922, p. 344—351), H. W. Turner (1928, p. 70—7 6), and Besairie (1953, p. 20—147, sheets 3, 5, 6, 8—11, 13). Much of the following description is drawn from these reports. Monazite occurs in the Malagasy Republic as an accessory mineral in kyanitic, sillimanitic, and cordi— erite-bearing fine-grained biotite gneisses (leptynites) ; coarse-grained mica schists and gneisses; quartz-poor aluminous schists of high metamorphic rank (lambo- anites); Inigmatites, granites, pegmatites, and quartz veins. Local segregations of monazite have been observed in granites, and the mineral has been found disseminated in metamorphosed limestone at its contact with intrusive granite. N0 bedmck source has been commercially exploited for monazite. The crystalline rocks are deeply weathered, and erosion of the weathered bedrock has released monazite into stream AFRICA 35 sediments of Quaternary age. Some of these sedi- mentary deposits may prove to be exploitable placers. Monazite is so common in the rocks of the island that it was found in at least 90 percent of the 10,500 concen- trates studied by the Service Géologique [Madagascar] in 1955 (Behier, 1955, p. 140). Systematic studies of 964 concentrates from streams in the Ankaizina Mountains in the northern part of the island disclosed local deposits of monazite north of Antsaonjo and on the east flank of Analabe Berohitry (Emberger, 1956, p. 53—54). Around Antsaonjo the raw sand contained 0.01—1 percent of monazite, but most of it had 0.03 percent. A placer extending 2 miles along a stream northwest of Antsaonjo was estimated to contain a ton of monazite at a concentration equal to 1 percent of the alluvium (Emberger, 1956, p. 54). The richest stream deposits along the east flank of Analabe Berohitry contain as much as 0.8 percent of monazite, but the reserves are said to be economically insignifi- cant. To the northeast and adjacent to the contract be- tween two-mica granite and garnet-sillimanite gneiss in the Vicinity of Mananjeba, the streams are commonly monazite bearing, and concentrates from their alluvium contain 6—48 percent of monazite (Saint—Ours, 1956, p. 27). Monazite in the gravel, however, was said not to exceed 0.3 percent by weight. Monazite from the Mananjeba River was said to contain 4.1 percent of Th02 (Behier, 1960, p. 50). Around Marotolana in a region of migmatites having no visible granite, mona- zite is present in the streams, but high-tenor deposits had not been found as of 1956 (Saint-Ours, 1956, p. 27). Granitic and syenitic pegmatites have furnished large well-formed crystals of monazite for mineralogi- cal study, but, like pegmatites elsewhere in the world, they contain no economic concentrations of monazite. Pegmatites in the south—central part of the island are noteworthy for their monazite crystals. Between Miandrarivo and Mandoto, especially between Anki- sabe and Soarivola and around Ambatofotsikely (Duparc and others, 1913, p. 5—8; Ungemach, 1916, p. 19; Lacroix, 1922, p. 347; H. W. Turner, 1928, p. 76; Besairie, 1953, p. 54), monazite is associated with muscovite, beryl, almandine-spessartite, columbite, ampangabeite, ilmenorutile, striivérite, allanite, mala- con, orangite, and uranothorite in a broad zone of uraniferous pegmatites in gneiss and migmatite. Analyses of monazite from two pegmatites at Miandra- rivo and Ambatofotsikely, which had respective specific gravities of 5.11 and 5.27, showed that the monazite had the following composition: [Analystsz A, F. Pisanl (in Lacroix, 1922, p. 351); B, Duparc, Sabot, and Wunder (1913, p. 8). See also Arthur Holmes (1931, p. 374).] Percent A B 06203 __________________________________ 31. 85 26. 95 Lagos (group) ___________________________ 27. 90 32. 60 (Y, EI‘)203 ______________________________ 2. 93 . 30 Th02 ___________________________________ 9. 15 11. 23 P205 ___________________________________ 27. 45 25. 90 Si02 __________________________________________ 2. 87 A1203 ___________________________________ . 21 . 15 Fe203 ___________________________________ . 42 . 60 Zr02 _________________________________________ . 11 Taz05 ________________________________________ . 24 CaO _________________________________________ Trace Loss on ignition _________________________ . 74 . 56 Total __________________________ ,___ 100. 65 101. 51 A. East of Miandrarivo. B. Ambatofotsikely. A zone of beryl- and muscovite-bearing pegmatites lies southwest of Miandrarivo in the Ampandramaika- Malakialina area (Guigues, 1955, p. 43, 49). The pegmatites are in kyanite- and sillimanite-bearing mica schists on the northwest side of granite exposed be- tween Ihorombe and Ambararata. The pegmatites contain few accessory minerals and little monazite. Placer monazite is of such small consequence that it could only be a byproduct of mining for columbite- tantalite. Monazite is particularly abundant, however, in the granitic rocks of the Ihorombe—Ambararata area, and streams rising there are rich in monazite. Sedi- ments in the upper valley of the Belobaka River con- tain as much as 8 percent of monazite, and some sedi- ments from the Manatsahala River (Manantsahala River) contain 5 percent of monazite (Besairie, 1953, p. 82). Huge monazite crystals have been found in syenitic and granitic pegmatites around Itrongay in the south- western part of the island south of Ambararata and southwest of Betroka. The pegmatites are in gneiss and leptynite. Associated with the monazite are crystals of translucent yellow orthoclase, translucent diopside, clear green kornerupine, zircon, chevkinite, and euxenite. Strongly radioactive, monazite-bearing alluvial sediments have been deposited throughout the pegmatite district (Besairie, 1953, p. 114) . The Berere pegmatite field is a source of commercial beryl and columbite, and monazite is an associated accessory mineral (Giraud, 1957, p. 125, 130). The country rocks are pyroxene and amphibole gneisses, which to the west overlie migmatite. An external halo of biotite pegmatites surrounds the field and gives way inwardly to a band of two-mica pegmatites. Muscovite pegmatites occupy the center of the field. Monazite is 36 THE GEOLOGIC OCCURRENCE OF MONAZITE a very minor accessory mineral in the muscovite peg~ matites, which are composed of quartz, perthite, albite, muscovite, biotite, garnet, beryl, and columbite. It is more common in the two-mica pegmatites, which con- sist of quartz, albite, muscovite, biotite, garnet, euxenite, ampangabeite, allanite, zenotime, and zircon. It is a common accessory mineral in the biotite pegma— tites, which consists of quartz, perthite, biotite, garnet, very scarce beryl, fergusonite, samarskite, magnetite, and thorite. Beryl-bearing potassic pegmatites in gneisses, mig- matites, and granites around Mount Vohambohitra in the Ankozobe and Anjozorobe districts of the north- central part of the island contain accessory monazite, samarskite, fergusonite, and striivérite (Lacroix, 1922, p. 345, 349; Giraud, 1955, p. 39—40). Giraud (p. 42) suggested that monazite could be recovered as a by- product from the mining of fergusonite in the Mount Vohambohitra area. A granitic pegmatite on Mount Vohambohitra, lacking beryl and uranium minerals, contains monazite which has 8.9 percent of Th02. Elsewhere in the area monazite accompanies columbite- tantalite in zones of kaolinized perthite at the contact of veinlets of smoky quartz with pegmatite (Behier, 1955, p. 140). In the extreme northwestern part of the island, a west-flowing stream called the Andranomalaza rises along a contact between granite and gneiss and empties in the Baie de Sahamalaza (Baie de Port Radama). Sedimentary deposits of this stream are monazite bearing (Besairie, 1936, p. 228). Monazite crystals have been collected from eluvium derived from bastnaesite- and chevkinite-bearing peg- matites in granite gneiss at Ambahy in the south— central part of the island west of Finandrahana (Lacroix, 1922, p. 349; Besairie, 1953, p. 89). Beryl-bearing pegmatite veins at Tongafeno near Betafo contain monazite and hatchettolite (Lacroix, 1911, p. 561). This is the first locality where primary monazite was found in the Malagasy Republic, its presence in this locality being predicted by Lacroix (1909) in his discussion of monazite—rich gold placers. Monazite crystals are associated with hatchettolite and blomstrandine in rose quartz that is quarried between Betafo and Antsirabe, in central Malagasy (Hintze, 1922, p. 344). Monazite was reported to occur in the alluvium at Antsirabe (Holmes and Cahen, 1955, p. 26). Monazite from an undescribed source at Ampangabe contains 15.38 percent of Th02 (H. W. Turner, 1928, p. 82). Monazite from Morarano to the northeast of Tanana- rive was reported to be nonradioactive; its source was not described (H. W. Turner, 1928, p. 82) . Pegmatites consisting of graphic intergrowths of quartz and perthite and some biotite occur in biotite gneiss near Befanamo (Guigues, 1954, p. 69—70). Dis- persed lenticles of quartz, perthite, beryl, muscovite, columbite-tantalite, and thortveitite in the pegmatites contain small amounts of monazite. The probable order of crystallization was beryl, columbite-tantalite, fergusonite, euxenite, and monazite, then stiivérite and thortveitite, and last zircon and xenotime( ?). At Miarinkofeno 2 miles northwest of Befanamo, monazite is abundant in veins of pegmatite that is similar to the pegmatites at Befanamo. About 5 miles northeast of Maharidaza, veins of pegmatite conform to the layer- ing in amphibolite; they contain sheet muscovite, biotite, monazite, magnetite, garnet, tourmaline, beryl, and columbite. These veins of pegmatite are described as being particularly rich in monazite (Guigues, 1954, p. 7 O). Eluvial placers are derived from the pegmatite. Fine-grained accessory monazite occurs in cordierite lamboanite at Ankaditany near Zazafotsy in the ex- treme south—central part of the island (Lacroix, 1956, p. 8). Monazite is a normal accessory mineral, but also occurs as lodes and segregations, in an ancient granite in the extreme southeastern part of the island north of Fort—Dauphin (Besairie, 1948, p. 120; 1953, p. 146). Locally the concentrations are high, but they are of small size and not economic (Lecoq, 1957, p. 592). Imerinite—bearing metamorphosed banded limestone that is exposed at Ambatoarina, east of Ambato- fangehana in the central part of the island, contains microscopic, disseminated crystals of yellow monazite. This limestone is intruded by granite and by veins of calcite pegmatite composed of calcite, quartz, micro- cline, albite, celestite, ambatoarinite, and monazite. Tiny crystals of monazite occur as an accessory in the granite, but in the calcite pegmatite the grains of mon- azite are as much as 1 millimeter across and tend to aggregate into granular masses. Monazite having a specific gravity of 5.25 was recovered from eluvial soil trapped in cavities in the metamorphosed limestone and was analyzed and found to have the following composition (Lacroix, 1922, p. 349-351). Percent Ce203______ ________________________________ 39. 51 (La, Di)203 ________________________________ 27. 80 ThOg _____________________________________ 1. 05 P205 ______________________________________ 30. 18 F6203 _____________________________________ . 92 CaO _____________________________________ . 46 Loss on ignition ___________________________ . 47 Total _______________________________ 100. 39 Detrital monazite has been found in streams in the eastern interior and along the east coast of the Mala- AFRICA 37 gasy Republic from as far north as Presqu’ile Masoala southward to Fort-Dauphin and thence westward to the Baie des Gallions. Throughout much of this tract, monazite also is found in beach sands. Both the frequency with which fluvial concentrates contain monazite and the amount of monazite they contain along the east side of the island increases southward from Presqu’ile Masoala. This southward increase in the abundance of monazite seems to parallel a south- ward increase in the plutonic character of the crystal- line rocks. Around Presqu’ile Masoala, the Baie d’Antongil, and southward for some 20 miles, granite intrudes schists and is filled with inclusions of schist. The inclusions and wallrocks rise in metamorphic facies from chloritic and micaceous schists in the northern part to kyanitic mica schists in the central and southern parts of the area. At the north end of the granite, near Maroantsetra, where chloritic and micaceous schists are present, only 4 out of 10 concen- trates from stream sediments contained monazite (Besairie, 1953, p. 20). Monazite was found, however, in 35 out of 51 concentrates (68 percent) from stream sediments in the central and southern parts of the granite between Mananara and Pointe a Larrée where kyanitic rocks are present (Besairie, 1953, p. 34). Streams draining kyanitic gneisses and schists near Fenerive and Vavatenina south of the granite were the sources of 67 concentrates, of which 50 (74 per- cent) had monazite (Besairie, 1953, p. 38). The mica schists and gneisses along the east side of the island become increasingly plutonic in character south of Fenerive and Vavatenina. Sillimanite and corundum occur, and in the interior of the island west of Vavatenina, a zone of granitic migmatite crops out and extends southward. Farther south in the Ampasi- nambo region west and northwest of Mananjary, a zone of granitic migmatite is found in kyanitic and sillimanitic gneisses and schists, and monazite is common in sediments along all the streams in the area (Besairie, 1953, p. 94; Saint-Ours, 1955, p. 23). The greatest concentrations of monazite are in gold placers along the Ampasary River between Ambalavia and Antanamboa. Southeast of the Ampasary River in the drainage basin of the Mananjary River, where monazite mining has been attempted (Besairie, 1953, p. 101; H. W. Turner, 1928, p. 82), small round grains of monazite, apparently derived from the gneisses of the district, are common ‘in most of the streams and are especially abundant in the Saka River. Monazite from the Mananjary River contains 8.6 percent of Th02 (Behier, 1960, p. 50). The detrital monazite from the Saka River contains 90—100 percent of Th02 (Lacroix, 1922, p. 350—351). Accompanying monazite in the Mananjary River and its tributaries are detrital kyanite, sillimanite, staurolite, corundum, rutile, almandine, hornblende, augite, magnetite, ilmenite, zircon, and gold (Lacroix, 1909, p. 314). Clean monazite from the mouth of the Mananjary River contains 10 percent of Th02 (Lacroix, 1909, p. 317). Sillimanite quartzites and gneisses, garnetiferous leptynites, cordierite leptynites, and vast zones of migmatite which has bands of graphite occupy the central and eastern parts of the island and extend south from the Ampasary basin to the vicinity of Fort-Dauphin where ancient granites are exposed. Sediments in streams throughout this region contain monazite. Sand at the mouth of the Mananara River east of Vangaindrano has abundant monazite (Besai- rie, 1953, p. 126), and thorium—rich monazite occurs in almost every stream in the southern and south- eastern parts of the Malagasy Republic (Besairie, 1948, p. 120). . The rocks in the extreme southeastern part of the island are of the granulite facies of regional meta- morphism (Roche and Marchal, 1956, p. 142—144; Besairie, 1954, p. 107, 110; Behier, 1960, p. 50) and are highly migmatized and granitized in many places. Phlogopite and thorianite occur in the diopside pyrox- enites, and monazite and apatite occur in intragranitic lentils in which the monazite makes up as much as 30 percent of the lentil. Iron-rich layers contain garnet, spinel, sillimanite, magnetite, hypersthene, and phlogopite in association with arsenopyrite, monazite, and cassiterite. Many of the mineralized lentils are masked by eluvium; thus, their sizes have not been well defined (Roche and others, 1956, p. 154—156). Because the monazite-apatite lentils resemble the great monazite- apatite vein at Steenkampskraal in South Africa, con- siderable attention has been paid to the possible occur- _ rence of a large deposit in the granulites of the south- eastern part of the Malagasy Republic, but as of 1960 none had been reported. The monazite—apatite veins northwest of Fort-Dauphin contain reserves of 35—80 tons of monazite each. In addition to segregations of monazite and apatite in granitic rocks, smaller deposits of monazite segregated with other minerals have been found in ferromagnesian rocks. The segregations include biotite and monazite; ilmenite, apatite, and monazite; ilmenite, zircon, and monazite; phlogopite, apatite, and monazite; and garnet, monazite, and apa- tite. The following chemical composition of monazite from the monazite-apatite metamorphic differentiation 38 assemblages was determined by P. Rose (Roche and others, 1956, p. 156): Manangotry assemblages: Th0: REaOs 1 _____________________________ 12. 37 55. 81 2 _____________________________ 10. 28 57. 66 3 _____________________________ 6. 46 59. 4O Ampasimena assemblages: 1 _____________________________ 7. 77 57. 70 2 _____________________________ 5. 28 62. 28 Another analysis of monazite from pegmatite at Ampasimena was given by Behier (1960, p. 50); this analysis showed 1.83 percent of Th02 and 63.65 per- cent of REOz. Monazite from granite in the vicinity of Vohimena contains 7.8 percent of Th02 (Behier, 1960, p. 50). LI'I'I‘ORAL DEPO S ITS Beach placers have not been prospected from Fener- ive northward along the northeast shore of the Mala- gasy Republic, but some monazite probably occurs in ilmenite placers north of Pointe :2» Larrée (Besairie, 1953, p. 21, 44). To the south, beach sands between Vatomandry and Manakara were reported (Harris and Trought, 1952, p. 48) to contain as much as 2 percent of monazite. This stretch of beach is flanked by basalt flows of Cretaceous age that extend south- ward nearly to Manantenina, but monazite was reported (Lacroix, 1909, p. 317; Besairie, 1953, p. 101, 126) to be deposited at the mouths of the Mananjary and Mananara Rivers and to be concentrated along the beaches south of the Mananara River. Between the mouth of the Mananara River and Manantenina, the basalt flows pinch out and from the bay at Manan- tenina southward to the Baie des Gallions, extensive prospecting on the beaches has revealed placers that are rich in monazite and zircon (Lamcke, 1937, p. 117 ; Besairie, 1953, p. 146; Roche and others, 1956, p. 147; Lecoq, 1957, p. 591; Behier, 1960, p. 50). Descriptions of the monazite placers on the south- east coast of the Malagasy Republic from the mouth of the Mananara River to the beaches west of Fort— Dauphin were given by Roche, Marchal, and Delbos (1956, p. 147—152), and they are summarized in the following text. Marine sands form a belt 1000—5000 feet wide along the southeast coast. Locally the belt may be broken by rocky promontories, or widened at the mouths of rivers, or extended by dune systems. In the vicinity of Fort—Dauphin, rocky capes and bays are bordered by marine sand which extends several miles inland. Some beaches form a zone 35—160 feet wide upon which the surf falls, and there monazite may become highly concentrated. Ancient raised THE GEOLOGIC OCCURRENCE OF MONAZITE beaches lie between the present beaches and the first dunes. These ancient beaches have a barren over- burden beneath which rich placers are buried. The dunes are classed as modern and old. Modern dunes are composed of white sand, are barren or nearly barren of vegetation, and form low-tenor deposits of large volume. Old dunes are weathered yellow or red and have rubified and consolidated sand at the base, a bleached surface, and diverse fixed vegetation. Placers in the old dunes are less rich than the beaches but they uniformly contain 25—30 percent of heavy minerals, of which 1.2—1.5 percent is monazite, and they are of enormous volume. More than 80 percent of known reserves are in the old dunes. Eleven of the present beaches south of the mouth of the Mananara River were explored (Roche and others, 1956, p. 151). Total estimated tonnage of black sand is 110,000 short tons of which 3,000 short tons is monazite, 4,000 short tons zircon, and 88,000 short tons ilmenite. Two deposits, one known as the Bofasy-Ilanamainty and the other as the Fort- Dauphin, contain 80 percent of the reserves. Sixteen old beach and dune deposits were explored in the same stretch of coast and were reported (Roche and others, 1956, p. 152—153) to contain 2,700,000 short tons of black sand in which there are 35,000 short tons of monazite, 44,000 short tons of zircon, and 770,000 short tons of ilmenite. The ilmenite contains 50.7— 57 .9 percent of TiOz with traces of chromite. Analyses of beach and dune sands from the area are given in table 5. An analysis of monazite sand from an unspecified locality in the Malagasy Republic is given by Hintze TABLE 5.—Thortum and rare-earth content of monazite from beach and dune placers along the southeast coast of the Malagasy Republtc [Analystz P. Rose (in Roche and others, 1956, p. 153) and F. Rut (in Behier, 1960, p. 50). Size of deposit: Large, estimated more than 5,500 short tons of monazite; Medium, estimated $1,100 short tons of monazite; Small, estimated 200—700 short tons of monazite] Kind of Size of Th0, RE203 deposit deposit Vangaindrano, mouth of Beach _______ No data _____ 7. 38 57. 40 Mananara River. Ambalaiandra ________________________ do ______ Small _______ 7. 25 52. 30 Ilanamainty (Betasy) _________________ do ...... Large ....... 7. 45 56. 60 Ambinan’Andringitra ........... Dune ....... Small ....... 7. 70 59. 86 Vohibarika: 6. 84 59. 16 7. 88 59. 02 9.04 58. 46 7. 52 58. 63 Ihabakoho ....................... 5. 90 62. 78 Fan-Dauphin (Abattoir). _ -__ 6. 68 56.92 Ambasivasy _______________ 9. 0 57. 5 Amboan itelo _____________ 5. 28 62. 28 Ranoma nty-Vangaindrano __- 9.07 57.86 Papango ______________________________ do ...... No data ..... 8.64 57.82 Ikalomanga ___________________________ do ______ No data ..... 9. 44 57.71 Ampasimeloka: North ____________________________ do ______ N 0 data ..... 7. 40 56.00 South _____________________________ do ...... No data ..... 7. 05 57. 00 AFRICA 39 (1922, p. 370) as having 5.5 percent of Th02. The sample seems to have been a mixture of minerals, in- cluding quartz, several percent of rutile and zircon, and nearly 10 percent of ilmenite. Monazite in this mixture could have at least 6.9 percent of Th02. Beach sands at a locality called the Abattoir on the west side of Fort-Dauphin were discovered by the Commissariat a l’Energie Atomique and were mined and processed from 1954 by the Société des Monazites de Madagascar (Lecoq, 1957, p. 591). Rare earths and thorium were separated from the monazite, the rare earths going to the company and the thorium to the C.E.A. In 1956 the output from Abattoir was about 220 short tons of monazite. This monazite contains about 8 percent of thorium oxide. In 1923 the national output of monazite from fluvial placers in the Malagasy Republic was 1.6 short tons (Turner, H. W., 1928, p. 82), and in the first quarter of 1924 exports of euxenite and monazite were 1.3 short tons (Madagascar Direction des Mines, 1924). Monazite production in the Malagasy Republic between 1955 and 1961 was said by John G. Parker (written commun., 1962), US. Bureau of Mines, to have been as follows: Short tons 1955 ______________________________________ 72 1956 ______________________________________ 168 1957 ______________________________________ 331 1960 ______________________________________ 471 1961 _ - - _; _________________________________ 503 Along the west side of the island, monazite has been discovered only at Anakao where marine beach and dune sands that are very rich in garnet contain a little monazite (Besairie, 1953, p. 111). MAURITANIA Dune and beach sands along the Atlantic coast are locally monazite-bearing from Saint—Louis in the south to Port—Etienne in the north (Dropsy, 1943, p. 251— 262). Sand at Sbar contains 6 percent of heavy min- erals dominated by ilmenite but including garnet, zircon, tourmaline, monazite, topaz, and barite. from stable dunes at Nouakchott (Nouak-Chott) has some ilmenite and zircon and a few grains of tourma- line, monazite, garnet, staurolite, and barite. White dune sand at Lemsid contains ilmenite, monazite, zircon, and sparse garnet, staurolite, and tourmaline. Beach sand at E1 Memrhar (El Manghar) is un— usually rich in heavy minerals. It consists of 50 per— cent of quartz, 45 percent of ilmenite, and 5 percent of zircon and garnet; a little sphene, some magnetite, and very sparse monazite are also present. Sand ‘ l MOZAMBIQUE Few descriptions of monazite in Mozambique have been published, and apparently little has been done to explore for it (South African Mining Eng. Jour., 1947, p. 771). It was said to be found within a radius of 30 miles of Tete, but the mode of occurrence was not specified (Mining J our., 1949). The pegmatites at Alto Ligonha are monazite bear- ing and are the most frequently described monazite localities in the country, but they are not economic sources of monazite (Marble, 1948, p. 26; Hutchinson and Claus, 1956, p. 757—759; Bettencourt Dias, 1957, p. 279). Monazite is found with columbite, beryl, lepidolite, and bismuth in strongly zoned pegmatites in Precambrian quartz-biotite schist, quartz-muscovite schist, amphibolite, and granitic gneiss of medium to high metamorphic rank. Pegmatites in the schists are more likely to have monazite than pegmatites in the granite gneisses. An analysis showed that mona- zite having a specific gravity of 5. 22 from a pegmatite at Boa Esperanca 1n the Alto Ligonha district had the following composition: [Analyst Sousa Torres (1952, p. 189—190)] Percent Percent 0e20, _______________ 24. 3O TlOz ________________ 0. 97 LagOg _______________ 25. 34 Sn02 ________________ Trace Y203 ________________ 1. 53 CaO ________________ 1. 60 Th02 _______________ 9. 84 MgO _______________ . 65 U303 ________________ . 00 PbO ________________ Trace P205 ________________ 27. 35 MnO _______________ . 98 SiOz ________________ 5. 76 H20 ________________ . 35 A1203 _____________ . 12 —— F6203 _______________ 1. 04 Total _________ 99. 83 Massive monazite-bearing pegmatites are widely ex— posed in the drainage basins of streams in the Ribawe Mountains (Holmes, Arthur, 1917, p. 40; 1931, p. 372). The region is underlain by biotite gneiss, horn- blende gneiss, gneissic and porphyritic granite, marble, biotite granite, and augite granite. Heavy-mineral residues from the gneissic granite and biotite gneiss do not contain monazite, but alluvium in the Bwibwi, Sawa, Matupa, and Nrassi Rivers is locally monazite bearing (table 6). The beach sand between Mozambique (Mocam- bique) and Quelimane was reported to have concen— trations of heavy minerals among which are monazite, rutile, zircon, columbite, euxenite, and samarskite (Mining World, 1954). Monazite is present in the sand at the mouth of the Rovuma River (Ruvuma River) on the border with Tanganyika. As much as 1 percent of the black sand at Vila Luiza (Marracuene) is monazite (Davidson, 1956a, p. 202). This monazite was said to contain 5 percent of Th02. 40 TABLE 6,—Mineralogical composition of monazite-bearing con- centrates from streams in the Ribawe Mountain area, Mozam— bique [Arthur Holmes (1917, p. 83, table 10). Symbols used: A, abundant; 0, common; , rare] 1 2 3 4 5 6 7 Magnetite ________________ C C C C C A C Ilmenite __________________ A A A A A A A Garnet ___________________ R R R R C R C Zircon ____________________ A A A A A A C Rutile ____________________ R R R R R R C Monazite_______’ __________ R R R C C R R Spine] ____________________ R R R R R _ _ _ _ Sphene ___________________ ____ R R R ____ -___ C Apatite ___________________ R R R R R C l. Sawa River. 2. Bwibwi River below confluence with the Sawa River. 3. Bwibwi River below mouth of a tributary from Mount Tipwi. 4. Matupa River at Matupa Pass, Rib-awe Mountains. 5. Bwibwi River above confluence of the Potela Mazi. 6. Nrassi River. 7. Nrassi River. Although the origin of the monazite is unknown, the following output was reported from Mozambique (J. G. Parker, written commun., 1962): Short tons 1957 ______________________________________ 0. 5 1958 ______________________________________ . 1 1960 ______________________________________ l. 0 1961 ______________________________________ . 2 NIGERIA Detrital monazite was lmown to be present in Nige- ria at least as early as 1902, and within the following decade its distribution, especially its association with tin (cassiterite) deposits, was reasonably well defined (Comité de l’Afrique Frangaise, 1904; Chemische Zeitschrift, 1904; Dunstan, W. R., 1906a, p. 7—8; 1912, p. 7; 1913, p. 12; Falconer, 1912, p. 544). Monazite is a fairly common accessory mineral in concentrates from tin placers in the Plateau Province of northern Nigeria, but in only a few places does it make up as much as 5 percent of the concentrate. Thorite, in abundances that are as much as 1 percent of the concentrate, occurs with the monazite and cas- siterite. Ilmenite, columbite, zircon, garnet, and wolf— ramite are present. Rutile and magnetite are scarce (Mackay and others, 1949, p. 13, 15). The principal source of the monazite in the Plateau tin fields is Precambrian metasedimentary rocks consisting of migmatite, biotite gneiss, granitic gneiss, calc-silicate rock, and quartzite of probably the upper amphibolite facies. A lesser source is the granites of metamorphic derivation emplaced in the Precambrian gneisses. These rocks contain a scant amount of columbite and no thorite or cassiterite, minerals which are related to a group of younger intrusives including pyrochlore- bearing riebeckite granite, biotite granite, greisen, and tin veins (Mackay and others, 1949, p. 13—57). In THE GEOLOGIC OCCURRENCE OF MONAZITE central Nigeria, monazite is found in cassiterite- and columbite-bearing eluvial placers and pegmatites as- sociated with granites that resemble the old granites of northern Nigeria (Imperial Inst. London, 1947). Alluvial monazite has been found at many places in southern Nigeria, but no littoral or deltaic placers have been reported from the coast or the mouths of the Niger River. Early mineral surveys reported monazite in concen- trates of alluvium from several places in the Oban Hills and the northern part of Calabar Province where. crystalline rocks rise above the coastal swamps and the belt of Cretaceous and younger sedimentary rocks (Dunstan, W. R, 1906a, p. 7—31; Raeburn, 1927a, p. 73). In this area, old quartz—mica schists, horn- blende schist and gneiss, and gneissic porphyritic biotite granite associated with pegmatite are intruded by syenite, basalt, and diabase. Monazite—bearing alluvial sediments do not form large deposits. They are confined to the present channels of the streams, and most are small pockets deposited on scoured rock flanked by low, bare, rocky cliffs. Data from these early surveys are given in table 7. Later search re— TABLE 7.—Mineralogical composition of monazite-bearing con- centrates from streams in the Oban Hills area, Nigeria [Compiled from W. R. Dunstan (1906a, p. 11-31). Symbols used: A, abundant; 0, common; S, scarce; Tr., trace; P, present] 1 2 3 4 5 6 7 8 9 10 Monazite . _ _ Ilmenite. _ Magnetite A A P Stantolite. Rutile. _ .-.. Columbite ....... Corundum ________________ l. About 10 miles north of Obong. 2. Tributary to Ukpong River. 6.49 percent Th0: in concentrate. 3. Ukpong River northeast of Ibum. 4.20 percent Th0, in concentrate. 4. Greek southeast of Ibum. 5.18 percent Th0. in concentrate. 5. Ibum-Nsan path 6 miles south of Ibum. 5.34 percent Th0. in concentrate. 6. Calabar River upstream from the Iyanyita River. 7. Uwet district (87 concentrates). 8. Oban Hills (60 concentrates). 9. Netim—Ibum path, near Calabar River (4 concentrates). 10. Ibum (3 concentrates). vealed that monazite was most abundant in the Netim- Ibum triangle, the Okarara district, the Akwa Ibame cassiterite area, and in the Kwa River, but none of the deposits is of commercial size and grade (Raeburn, 1927a, p. 85—86). Composition of concentrates from the Calabar area is given in table 8. Eight chemical analyses of monazite concentrates of variable purity were given by W. R. Dunstan (1906a, p. 12, 13, 30, 31). They showed from 3.18 to 6.49 percent of Th02 in material containing from 65 AFRICA 41 TABLE 8.~—Mineralogical composition of monazite-bearing concentrates from streams in the Calabar area, Nigeria [Modified from analyses by Raeburn (1927a, p. 87). Symbols used: VA, very abundant; A, abundant; 0, common; S, scarce; VS, very scarce] 1 2 3 4 5 6 7 8 9 10 11 12 Ilmenite _______________________________ C VA VA VA VA VA VA VA VA VA VA VA Magnetite _____________________________ S ____________ C S C S ____________ VS C C Rutile ______________________________________ VS S VS ______ VS VS ______ VS VS ______ VS Tourmaline ____________________________ A C C ____________ S VS S ...... C S S Cassiterite _____________________________ VA ______________________________________________________ S Garnet ________________________________ A A A ______ C S C C A A C S Epidote _______________________________ VS _________________________ S ________________________ VS » VS Monazite _______________________________ C S C S S S A VS S S A A Sillimanite _________________________________________ VS ____________ S ______________________________ Zircon ____________________________________________ S A A C A ______ C VS A A Apatite _________________________________________________ C C ____________________________________ Anatase _________________________________________________ V S __________________________________________ Gold ________________________________________ VS VS ______________________________ V S ____________ 1. Uyana Ikpofia. 2. Kwa River at Oban-Nsan road. 3. Ebara River at Oban-Nsan road. 4. Niaji, at the Upper Enimayip. 8. Ndebbiji, Ikpan River. to 99 percent of monazite and indicate that monazite from the Oban Hills has from 4 to 7 percent of Th02. Johnstone (1914, p. 57; 1918, p. 375; Imperial Inst. [London], 1914a, p. 59) reported that many analyses of monazite from southern Nigeria gave an average content of 5.8 percent of Th02 and that analyses from northern Nigeria gave an average content of 5.5 per- cent. Six of these analyses are given in table 9. TABLE 9.—Chemical analyses, in percent, of monazite from Nigeria [Analystz J ohnstone (1914, p. 57)] 1 2 3 4 5 6 CeaOa ___________________________ 30. 72 36. 53 30. 50 30. 38 34. 58 31. 40 L320: (group) .................. 30. 02 30. 00 28. 80 29. 60 29.83 29. 20 . 2. 74 .39 1. 43 1. 33 1. 29 2.00 5. 00 3. 20 8. 00 6.19 2. 30 5. 50 26. 29 28. 29 28. 16 29. 70 29. 71 29. 92 1.20 .63 1.79 .85 .73 .82 . 35 . 10 . 20 . 10 ........ . O5 3. 00 1. 20 . 81 1. 50 1. 80 . 75 .15 .21 .17 .16 .19 .10 .25 .20 .21 .33 .21 .44 Northern Nigeria: 1. Ekole. 2. Kadera. 3. Jarawa River, Naraguta. Southern Nigeria: 4. Iboboto stream, Nsan-Oban trail. 5. Between Iboboto stream and Ebara River. 6. Ebara River. Concentrates from a creek at Okpudu and from Oyi stream in the Abagana district northwest of the Oban Hills contain less than 1 percent of monazite (Dun- stan, W. R., 1913, p. 12). Minable deposits are un- known in the district. Several streams in the vicinity of Benin City were said to be monazite bearing, but here also the mona- zite makes up less than 1 percent of the concentrate (Dunstan, W. R., 1912, p. 7). Associated with the monazite are abundant zircon and ilmenite and sparse rutile, staurolite, kyanite, tourmaline, garnet, and magnetite. Occurrences are at Eleru stream near Siluko, the stream heading between Okwa and Igolaw, 5. Niaji, the Middle Enimayip. 6. Niaji, the Lower Enimayip. 7. Ndebbiji, lower Ikai Creek. 9. Oban, third creek on Okarara road. 10. Oban. Mango River. 11. Obutong, Lower Kinlkhe Creek. 12. Obutong, Upper Kinikhe Creek. Abega stream, Ikpoba River, Ohuma River, Ohi River, Oroghodo River (Orogodo stream) at Agbor, and Nyama stream. Cassiterite-tantalite concentrates from streams be- tween Wamba in Plateau Province and Egbe in Kabba Province invariably contain green to greenish-brown monazite. Although monazite has been identified in only a very few pegmatite dikes in the region, it is thought to have come from them (Jacobson and Webb, 1946, p. 23). In the paragenetic sequence for these dikes as interpreted by Jacobson and Webb, monazite, together with other phosphate minerals, was question- ably assigned a narrow range between the pegmatitic and hydrothermal stages when highly differentiated solutions crystallized to form complex pegmatites with or without replacement. Monazite is a minor but constantly present mineral in concentrates from cassiterite placers in the Mama area in Nassawara Province (Raeburn, 1926, p. 17). Ilmenite and rutile are the most abundant minerals in the concentrates (table 10). None of the placers is an economic source for monazite. The Mama area is underlain by biotite gneiss in- truded by gneissose feldspathic granite, gneissose biotite granite, pegmatite dikes containing tourmaline, monazite, and cassiterite, and a late sequence of in- trusive rocks which includes cassiterite-bearing gran— ite (Raeburn, 1926, p. 12, 17 ). Near Bauchi two bodies of monazite-bearing syenite are exposed (Bain, 1926, p. 64). In southeastern Zaria Province, fine-grained biotite gneiss is intruded by gray porphyritic biotite granite, white feldspathic granite, augite syenite, and mattered tourmaline—bearing pegmatite dikes containing some cassiterite (Raeburn, 1927b, p. 11—12). Basaltic flows overlie these rocks in the southern part of the prov- 42 TABLE 10.—Mineralogical composition of concentrates from streams in the Mama area, Nassawara Province, Nigeria [Analyst Raeburn (1926, p. 18). Symbols used: V, very abundant; A, abundant; C, common; S, scarce] H to w ,5 tn 0: q as Ilmenite _____________ V V Rutile _______________ A C Garnet _______________ C A S C OO< O>< {1204 > O m<<1 S inel _______________ S assiterite ____________ S Topaz _______________ S C Tourmaline ___________ _ - _ _ _ _ _ _ Zircon _______________ A Monazite _____________ C A Epidote ______________ ____ ____ __-_ -___ Magnetite ____________ ____ ____ _-__ ____ I (or/201021 U) (I) IIIII'V" C O oommm >0 Halgolla Oya, Ula ane ____________________________ Hiniduma, Galle istrict____ Hunugedeniya, Ratgama. ._ Kalu-ganga near Ratnapura Karawita (Niriella Estate) ________________________ >0?»wa Kehelambuwa—wala, Ulapane _____________________ Kitulhane-amuwa, Ulapane ...... Kondurugala, Bambarabottuwa Kotadeniya, Monrovia Estate. Kotmale Oya, Ulapane _____________ w>www Kudapandi Oya, Kondurugala ____________________ Lawpitlya Oya, Mapitagama--.. Mahaweli Ganga, Bintenna ..... Malwatta Metihakka ________________________________________ wwobo Moon Plains Moon Plains, Niriella Eliya _________________ N amnkandure Dela, Dombagammana Nelluwa distrlct ______________________ Nelluwa district, Hinidum Pattu. _ . ---_____ Ud>>l>> >>>>O Niriella Ganga Panakuru Oya, Deraniyagala ___________ ‘ Patambe Ela Hiniduma ..... Pelawatta Ganga ___________ Pingawara _________________ Rakwana Ganga near Huduman Kuda ____________ Ranchagoda neat Mstara ........ Sehel Oya, Getahetta ......... Sitawaka Ganga, Avissawells- Sitawaka Ganga, Detaniyagala ......... >>>OO Walawe Ganga, Motahela, Balangoda .............. Weganga ___________________________ Weganga at Marapona __________________ Weralupe-dola near Ratnapura _________ CNN» Gem- and monazite-bearing alluvial gravels are ex- posed at three levels in the lower valley of the Kelani Ganga upstream from Colombo. The highest and old- est gravel is a terrace deposit of quartz—laterite con- glomerate. Concentrates from this weathered terrace material contain the merest trace of monazite. Con- centrates from a younger terrace gravel exposed at altitudes between the old weathered terrace and the present paddies of the Kelani Ganga have 2—3 percent of monazite. The youngest and lowest gravel is buried beneath the sand and clay of the paddies and is the source of concentrates having as much as 28 percent of monazite. Farther along the Kelani Ganga, as far as the mouth of the Sitawaka Ganga, old gem pits pro- duce few concentrates which contain more than 2 percent of monazite. Ilmenite is the dominant mineral in the concentrates, and the other minerals in order 58 of abundance are garnet, magnetite, hornblende, hyper- sthene, monazite, zircon, rutile, spinel, pyrite, silliman- ite, sphene, anatase, and native platinum. Along the Sitawaka Ganga above its mouth to the first rapids up- stream from Sitawaka village, the concentrates from alluvium consist of 70—80 percent of ilmenite, 1.5 per— cent of monazite, and a suite of other heavy minerals similar to those in the Kelani Ganga, except that tour- maline and corundum are present. The tenor in mona- zite in this part of the stream is only about 0.2 pound per cubic yard of sediment. Upstream from Sitawaka village the greatest tenors in monazite are 1 pound per cubic yard of sediment, monazite being about 5 percent of the concentrate. Inasmuch as the placer ground along the Sitawaka Ganga is shallow, is subject to frequent severe floods, and has been widely mined for gems, it is unlikely to be a commercial source of monazite. Alluvial deposits explored east of Adam’s Peak in the streams around N uwara Eliya in the south-central and southeastern parts of Ceylon generally contain a little monazite (Imp. Inst. [London], 1916, p. 344—358), but this alluvium is less valuable for both monazite and gems than is that in streams farther west around Ratnapura. specimens of black monazite (Dunstan, W. R., 1910, p. 29). Monazite separated from other detrital minerals in the fluvial deposits of the Niriella Ganga was analyzed 3 by Johnstone (1914, p. 56; in Imp. Inst. [London], 1914a, p. 56; in lVadia, 1943, p. 9) and found to have the following composition: Percent Percent Ce203 ________________ 26. 71 SiOz _________________ 2. 47 L340; (group) _________ 30.06 A1203 ________________ .70 = Y203 (group) _________ 1. 46 F8203 ________________ 1. 09 l Th02 ________________ 10. 75 CaO _________________ . 85 I P205 _________________ 24. 61 Loss on ignition _______ . 93 e Detrital monazite from following oxides: [Analystz Imp. Inst. [London] (1916, p. 355, 367)] Percent 60. 121 Geo. (group) ___________________________ 63.62 ThOZ ___________________________________ 4. 96 4. 91 j, U308 ___________________________________ Trace _______ 1 $02 ____________________________________ 1. 88 _______ j The amount of thorium oxide in the samples of 3‘ detrital monazite from the Nuwara Eliya district is considerably less than the amount reported for mon-j azite from feldspathic granulite in the same district. A small pebble of detrital monazite found at Pusse Dola, Dela, in Sabaragamuwa Province contains 14.31 percent of Th02 and has a specific gravity of 5.42. Gem pits at Pingarawa have produced. placers between N uwaraE Eliya and Ambawela and from gullies in the Yalkum- bura area southeast of Nuwara Eliya contains the: THE GEOLOGIC OCCURRENCE OF MONAZITE Two determinations of Th02 and four determinations of U308 in monazite sand of unspecified provenance in Ceylon were reported by Satoyasu Iimori (1929, p. 230, 233) to have averages of 9.26 and 0.34 percent, respectively. BEACH PLACERS Beach placers where ilmenite, zircon, monazite, and rutile have accumulated are at the mouths of rivers emerging on the west side of the island and along most of the west coast of Ceylon (Nye, J. A., 1917 ; Soc. Chem. Industry Jour., 1917 ; Chem. Trade Jour. and Chem. Engineer, 1917a; 1917b; Imp. Inst. [Lon- don], 1917, p. 346; Coates, 1935, p. 183; Wadia, 1941, p. 18). About 2 percent of the heavy minerals from the beaches is monazite, which locally makes up 6—10 percent of the black sand and, in places, as much as ; 40 percent (Wadia, 1943, p. 8). Monazite in the beach placers is fine grained and rounded. No euhedral grains of monazite have been observed despite the com- mon occurrence of euhedral zircon and rutile (Imp. Inst. [London], 1916, p. 326). Inasmuch as tiny round anhedral grains of monazite are a common accessory mineral in the granulites of the island and are washed from the granulites into the streams, the size and shape of the monazite grains in the beach placers are prob— ‘ ably inherited. For the most part, the concentrates seasonally form narrow bands at or just below the high tide line. Changes in prevailing wind and direction of coastal currents may destroy old deposits and form new ones. Only in a few places are the beach placers large enough to be of economic importance (Coates, 1935, p. 183). The west coast from Colombo north to Mannar is low lying and is bordered on the east by sandstone and limestone of Miocene age (Coates, 1935, p. 186). Wind- blown sand is common along the coast, and in some regions, such ts the area north of Negombo, dunes ex- tend inland for miles. Natural concentrations of heavy minerals are found at high tide level at the heads of small beaches, and they range in thickness from a mere film to several feet. The monazite in the beach placers has been reworked from low coastal cliffs of sandstone. At many places the heavy minerals are strikingly in- terbedded with white sand. Near the mouths of sev— eral streams, notably the Maha Oya where concentrates contain 7 percent of monazite and the Gin Ganga and Kalu Ganga where concentrates contain 4—5 percent of monazite, the heavy-mineral deposits are larger than ordinary (Wadia, 1941, p. 18; 1943, p. 8). Local peculiarities of the shore currents or wave action haVe led to concentrations of monazite that reach 3—9 per- cent of the heavy minerals at Marawila beach, 12 per- cent at Welaboda, and 22 percent at Kudremalai. ASIA 59 These rich deposits seem to be small. The one at Kudremalai, 40 miles south of Mannar, was reported by the Imperial Institute in London (1916, p. 327) to be only 200 cubic yards in volume, and was said by Coates (1935, p. 186) to contain no more than 100 short tons of monazite. Southeastward from Colombo to Galle on the west coast and eastward from Galle to Hambantota along the south coast of Ceylon is a series of bays and head— lands formed from plutonic rocks. Sand dunes occur in a few areas, especially around Hambantota, and sedimentary rocks or raised coral reefs fringe much of the shore. Many small steep beaches have narrow im- permanent streaks of concentrates at the upper edge of the wave action (Coates, 1935, p. 185). Two dis— tinct types of heavy-mineral deposits have been recog- nized along these shores (Imp. Inst. [London], 1916, p. 329). In one, ilmenite predominates; the deposit is black, and it contains abundant monazite. In the other, garnet is predominant; the deposit is red, and monazite is sparse or absent. An unusually rich natural black sand from a bay at Kaikawala south of the mouth of the Bentota Ganga on the west coast contained between 40 and 50 percent of monazite. Concentrates from the deposit contain an average of 15 percent of monazite. The deposit fol- lows the shore of a shallow bay between two headlands which are joined by a narrow bar, 0.5 mile long be— tween the headlands and extending 2 miles north of the north headland. At certain seasons, particularly the change of the monsoon, good concentrates build up on the beach, but they never exceed a few inches in thickness. The placer was reported by Coates (1935, p. 185—186) to contain only 300 or 400 tons of monazite and was said to have been worked on a commercial scale for several years around the time of World War I, but records of output are not known. Analysis of a natural concentrate containing 47.5 percent of monazite from the bay at Kaikawala showed 29.91 percent of the cerium earths, 4.15 percent of T1102 and 0.18 percent of [7308 (Imp. Inst. [London], 1916, p. 330). Recalculated to 100 percent monazite, the amount of Th02 would be 8.7 percent. A beach at Induruwa on the southwest coast was ‘ mined between 1918 and 1922, and about 3,000 tons of black sand containing 15 percent of monazite was ex— tracted and processed. The deposits were not appre- ciably depleted, however, because after the minng was stopped fresh concentrates were formed by wave action (Fernando, 1948, p. 321). A deposit on the beach south of the mouth of the Bentota Ganga, but not otherwise identified, was re- ported to' have been the source of 299 short tons of . about 4 feet above sea level. monazite between 1918 and 1922 (Imp. Mineral Resources Bur., 1920, p. 7; 1924, p. 1; 1925, p. 5): Short tons 1918 ______________________________________ 22. 4 1920 ___________ \ __________________________ 80. 6 1921 ______________________________________ 84. O 1922 ______________________________________ 112. 0 Total ________________________________ 299. 0 Inasmuch as these records listed no other production from Ceylon during this period and the period was the: time when the placer at Induruwa. was mined, this output may be the actual production at Induruwa. Although the total is only about two—thirds as much as the estimate of production made by Fernando (1948, p. 321), a possible output for 1919 was not listed. It seems likely that this is the same deposit as the one said by Coates (1935, p. 185—186) to have been worked south of the mouth of the Bentota Ganga. Not all the black sand deposits on the southwest and south coasts are enriched in monazite. A large ilmenite deposit near Galle is practically devoid of monazite. Along the east coast of Ceylon few but large deposits of black sand have been discovered. The two largest are not related to any present drainage system, and they contain only a trace of monazite. They are at Tirukkovil and Pulmoddai. At Tirukkovil about 45 miles south of Batticoloa ilmenite placers nearly devoid of monazite have formed for 3 miles along the beach from the Tirukkovil resthouse (Coates, 1935, p. 185). The largest ilmenite deposits in Ceylon are at Pul— moddai on either side of the Kokkilai Lagoon 35 miles north of Trincomalee, but the placers have scant mona- zite (Coates, 1935, p. 183—185; Wadia, 1944, p. 8; Fernando, 1948, p. 320). The deposit is an old beach It is 150 feet wide and. 2 miles long; its seaward side slopes gradually down to low tide line. Black sand has been found for some distance offshore. On its landward side the black sand is covered with dunes. North of the old raised beach the modern beach is covered with black sand for 3 miles to the mouth of the Kokkilai Lagoon. According to Coates, the black sand is composed of 75 percent of ilmenite, 25 percent of zircon, and traces of magnetite and monazite. The placer was estimated by Davidson (1956a, p. 202) to contain at least 3 million tons of sand composed of 72 percent of ilmenite, 18 percent of rutile and zircon, and 0.4 percent of monazite. The best monazite placers in Ceylon are on scattered beaches southward from Negombo to Galle along the west coast (iVadia, 1944, p. 8), and from these deposits a steady output was maintained from 1952 at least through 1961 (J. G. Parker, written commun., 1962). During 1920 shipments of 79 short tons of monazite 60 THE GEOLOGIC OCCURRENCE OF MONAZITE were made (Vance, 1922), and in 1930 proposals were made to use the monazite at Induruwa as a source for helium for lighter-than—air craft (Mining J our., 1930). Exports of monazite from Ceylon in 1927, 1928, and 1929, respectively, were reported as 168 short tons, 122 short tons, and 93 short tons (Mining J our., 1930) or as 155 short tons, 112 short tons, and 85 short tons (Petar, 1935, p. 36). Despite these small discrepancies in statistics, Ceylon evidently was not a large producer of monazite. CHINA China seems to have produced no monazite, at least until 1952; however, by that time monazite had been identified among the heavy minerals in coastal and stream sands at several places in the southern, eastern, and northeastern parts of the country. In southern China, monazite in economically valuable amounts is associated with cassiterite in streams in the area of the tin-bearing placers that extends from the Chiang- hua hsien (Kianghwa district.) in southwestern Hunan Province into the Chung-sham hsien (Chungshan dis- trict), Fu-ch’uan hsien (Fuchuan district), Ho hsien (H011 district), and K’ung-chen hsien (Kungchen dis- trict) in northeastern Kwangsi Province (Peng, 1947, p. 111—115; Shen, 1956, p. 147). The placer monazite is derived from cassiterite-bearing granites that intrude limestone of early Carboniferous age and are overlain by Cretaceous sediments (Hsieh, 1943, p. 82). Eastern Kwangsi Province was reported by Shen to have alluv- ial monazite. Particularly extensive heavy-mineral de- posits were said to occur along the beaches in the southern part of Kwangtung Province, but details were lacking (Zenkovich, 1960, p. 355). In eastern China, monazite has been found in the beach sand of Chin-men tao (Quemoy) and other islands along the coast of F ukien Province opposite Taiwan, in stream sand in I hsien of Ho-pei Province (Wong, 1919, p. 215; Hsieh, 1926, p. 238—239), on the beaches in Shan- tung Province opposite Korea, and along the coast of the Liaotung Peninsula in Liaoning Province, Man- churia, adjacent to northwestern Korea. In northern China, monazite has been found in Heilungkiang Prov- ince, Manchuria, near the Amur River. A vein composed of fluorite, magnetite, pyrite, barite, and a rare-earth mineral resembling bastnaesite was found in 1933 in iron ore deposits at Beiyin Obo in Suiyiian Province 95 miles north of Pao-T’ou in Inner Mongolia (Ho, T. L., 1935, p. 279). Spectrographic analyses fail to reveal thorium, and mineralogical ex- amination of the material did not disclose monazite. The veins are very abundant in the iron deposit and extend outward into limestone. Descriptions of the deposit were brief; the amount of rare earths in one vein to a depth of 330 feet was estimated as 1,700 tons, but the total amount of rare earths in the area was not mentioned. If the vein system is part of a carbon- atite deposit, the resources in rare elements might be very large, and monazite may possibly be present in the area. Monazite-bearing placers along the coast of Taiwan were discussed by Ichimura (1948), Chen (1953), C. S. Ho (1953,, p. 203—211), and Shen (1956). Their re- ports showed that Taiwan is divided by a north-north- east-trending Central Range into a narrow, steeply sloping ea tern side that leads to the Pacific Ocean and a bro d, gentle western slope that steps down to the Formosa Strait. Souhward the flat western coastal area exparlds in width and is occupied on its seaward edge by tidal marshes. N orthward the western coastal area contracts into a series of narrow river flats and lateritic terraces. A group of Pleistocene cones, called the Tatun volcanoes, rise abruptly at the north end of the island. Along the short east slope and in the core of thel Central Range, schists, gneisses, and gran- itic rocks are exposed. Overlying the plutonic rocks on the wes side of the island are Tertiary slates and unmetamojtphosed Tertiary formations consisting of conglomer te, sandstone, shale, limestone, and some pyroclasticidebris and flows. Monazit occurs in the plutonic rocks of the Central Range. Itl is widely distributed in small amounts in the Tertiary sedimentary rocks where it is associated with heavy minerals derived from silicic igneous and metamorphic rocks. The plutonic core of the Central Range is regarded as a minor source of the heavy minerals in the Tertiary formations. The major source is inferred to be unexposed metamorphic monazite- bearing rocks that bordered the Tertiary basin of Taiwan. Stream and beach deposits derived from the plutonic rocks and Tertiary sediments also contain monazite. Small amounts of monazite have been de- tected (Ichimura, 1943, p. 1, 11, 20) in zirconiferous stream sands that originated in Pliocene basalt fields but were modified by detritus from nonvolcanic sources. Three types of beach and stream placers were rec- ognized by Chen (1953) and C. S. Ho (1953, p. 203— 211). In one type of placer the monazite together with other heavy minerals is concentrated on the surface or under shallow overburden in sand and gravel along the beaches or in sand dunes near the coast. The most enriched parts are along the high tide line or the storm beach above the high tide line. These layers of black sand range in thickness from a fraction of an inch to about 1 foot. This type of placer has best formed along the north coast of Taiwan where the ASIA 61 heavy minerals—composed of 80 percent of magnetite, 14 percent of ilmenite, 5+ percent of hypersthene, brown hornblende, rutile, and apatite, and less than 1 percent of zircon—are derived chiefly from the Tatun volcanoes. Monazite is generally absent from the beaches and dunes at the north end of Taiwan; but at one locality, Chienchowtze, Tanshui hsien, the heavy sand contains 0.04 percent of monazite. Contributions from Tatun volcanoes to the suites of heavy minerals in the beach deposits wane southward along the north— west coast. Monazite and other heavy minerals char— acteristic of granitic rocks and gneisses, reworked from the Tertiary sediments, become more dominant. The average composition of concentrates from beaches along the northwest coast is 50 percent of magnetite, 35 percent of ilmenite, 9 percent of zircon, 1 percent of monazite, and 5 percent of garnet, staurolite, tour- maline, rutile, and epidote. Beach and dune deposits are scattered along the length of the northwest coast and are particularly abundant in T’ao—yuan hsien (Taoyuan hsien) at Kuanyih where monazite makes up 0.45 percent of the heavy minerals. In Hsin-chung- li (Chungli hsien) at K’an-t’ou-tzu (Kantoutsu) and Pen-tzu-chiang (Pentzekang) the average amount of the heavy minerals is 4.5 percent of the beach sand and reaches 40 percent of the beach sand in some spe- cially enriched layers. At K’an-t’ou-tzu and Pen—tzu- chiang the average depth of the deposits is 4 feet and the average tenor of the monazite is 0.8 percent of the concentrate. In beach deposits at Nanhaicha in Miao- li hsien (Miaoli hsien) and at Tashanchio in Houlung hsien, the amount of monazite reaches 1.2 and 2.0 per- cent of the concentrate, respectively. Along the south- west coast of Taiwan, dune deposits at T’ung-shan chou (Tungshanchow) and Hai-shan chou (Haishanchow) have 1.9 and 0.9 percent of monazite in the concen— trates, and beach deposits at Hai—shan chou have 2.0 percent of monazite in the concentrates. The south- ward increase of monazite in beach deposits along the west coast is paralleled by an increase in the zircon and ilmenite and a decrease in the magnetite. The second type of heavy—mineral deposit in Taiwan is formed in offshore bars deposited in elongated ridges 300—650 feet wide parallel to and 1—5 miles from the southwest coast. Eight bars totaling 20 miles in length have been explored between T’ai-nan hsien (Tainan hsien) and Yun-lin hsien (Yunlin hsien), and they were regarded by Chen (1953) as the most important heavy-mineral deposits on the island. The heavy min- erals are concentrated in long strings at the high tide line on the seaward side of the bars. The heavy min- erals are more abundant at places where the shore is slightly concave toward the land or where a channel or tidal inlet cuts the bar. The width of the bands of heavy minerals'is ordinarily 30—65 feet, but on the bar at T’ung-shan chou the belt of concentrates reaches 325 feet in width. In these belts the bar sand contains enriched layers having 20 percent of heavy minerals at the top of the bar. The concentration decreases to 1 percent of heavy minerals at a depth of 3 feet. Black sand from bars off the southwest coast is composed of 9 percent of magnetite, 45 percent of ilmenite, 35 per— cent of zircon, 1.5 percent of monazite, and 9.5 percent of other minerals. Seven localities along the south- west coast listed by C. S. Ho (1953, p. 203—211) for placers in offshore bars, and the amount of monazite in concentrates from the bars, are as follows: North of the mouth of the Pei-chiang ch’i (Pekang-chi), 2.0 percent of monazite; mouth of the Pa-chang ch’i (Pachiang-chi), 2.1 percent; T’ung-shan chou, 1.7 per- cent; Wai-san—ting chou (Waisantingchow), 1.2 per- cent; Wang-yeh-chiang (Sinpeikangshanchow), 1.0 percent; Ch’ing-shan-chiang Shan (Chingshankang- shan), 1.4 percent; and VVang—erh-liao Shan (VVantze- liaoshan), 1.0 percent. The third type of placer is in streams. High-grade concentrates form thin layers on or near the upper parts of bars in the convex sides of bends in the mid- dle or lower courses of streams that flow across the coastal plain in southwestern Taiwan. The average river bar contains less than 2 percent of heavy min- erals, and areas of rich concentration shift from place to place following the regimen of the stream. The average composition of concentrates from streams on the southwestern coastal plain was given by Chen (1953) as 5 percent of magnetite, 25 percent of ilmen- ite, 55 percent of zircon, 2 percent of monazite, and 13 percent of other minerals. Four main streams, the Pei-chiang ch’i, the P’o-tzu ch’i (Potze-chi), the Pa- chang ch’i, and the Ts’eng-wen ch’i (Tsengwen-chi), rise in the plutonic rocks of the eastern highlands and flow across the Tertiary deposits to the southwest coast of Taiwan. The percentage of monazite in the heavy minerals from their principal monazite-bearing tribu— taries was given by C. 8. Ho (1953, p. 203—211) as follows: Tributaries to the Pei-chiang ch’i: Houkoutze _____________________________________ 1. 8 Yenshuinan ____________________________________ 2. 2 Hou-liao (Houliao) ______________________________ 1. 7 Wan-lung (Wanti) ______________________________ 1. 8 Tributaries to the P’o-tzu ch’i: Liang ch’i (Hsiashuang—chi) ______________________ 1. 9 Lin-nei (Linnei) ________________________________ 2. 1 Weitzenei ______________________________________ 2. 3 62 Tributaries to the Pa—chang ch’i: Shang—ta ch’i (Shangtan) ________________________ 1. 5 Tung-kuo (Kuolutze) ____________________________ 1. 8 Totzetou ______________________________________ 1. 6 Tributaries to the Ts’eng—wen ch’i: Tributary southeast of An-yeh (Anyeh) ____________ 2. 0 Sutzu _________________________________________ 2. 8 Yung—lo (Tawenliao) _____________________________ 1. 8 Concentrates from sediments in two streams efliuent on the northwest coast, the Nan-k’an ch’i (N ankan-chi) and the Hung-mao chiang (Hungmaochuang), have 0.4 and 0.9 percent of monazite, respectively. Monazite has been found in stream sand north of Hua-lien ch’i (Hualin) and in beaches along the east coast of Taiwan, but little is known about the nature of its occurrence (Ho, C. S. 1953, p. 203—211). Particles of monazite and other heavy minerals from western Taiwan are generally not smaller than 0.05 mm 1101' larger than 0.5 mm. Most of the grains are be- tween 0.08 mm and 0.25 mm, and the shape ranges from euhedral to round, depending upon the origin, transportation, and deposition of the grain. The mon- azite is pale yellow to honey yellow and less commonly brownish red, brown, gray, or nearly colorless. Anal- yses of monazite from Taiwan show abundances of the rare earths and thorium oxide that are within commer— cial requirements for the combined oxides, but the material analyzed may have contained several percent of ilmenite and zircon: Chemical analyses, in percent, of monazite from Taiwan Analysts: 1-4. Not given by Chen (1953) 5—6. Given by Shen (1956, p. 150) as 3 ‘ 1911b; Jarvis, 1947, p. 71). Sinchu Research Inst, Taiwan and Associated Metals and Minerals Corp., U.S.A., respectively] 1-2. Beach sand, western Taiwan. 3. Alluvium, Chi-lung Tao. 4. Beach sand, western Taiwan. 5—6. Offshore bar, western Taiwan. Reserves of monazite in accessible areas of western Taiwan were estimated by Shen (1956, p. 150) to be 702 short tons along the northwest coast, 7,633 short tons in the offshore bars of the southwest coast, and 1,355 short tons in streams on the southwestern coastal plain. Neither the tenors nor the reserves in monazite are attractive for large—scale mining, and no produc- TI-IE GEOLOGIC OCCURRENCE OF MONAZITE tion of monazite has been recorded. Some monazite might be recovered as a byproduct from small-scale mining of ilmenite, rutile, and zircon; however, this is unlikely. Pertinent in this connection is Shen’s observ- ation (1956, p. 147) that the Japanese produced about 200 short tons of zircon from placers on Taiwan be— tween 1943 and 1945, but they did not attempt to recover monazite. FEDERATION OF MALAYA Malaya is underlain by sedimentary and volcanic rocks which range in age from Carboniferous to Trias- sic. They are widely intruded by granite. Associated with the granitic rocks as minor accessory minerals, or in veins, or in replacement deposits at the contacts between the granite and older rocks, are cassiterite, wolframite, scheelite, ilmenite, monazite, gold, and a variety of other heavy minerals (Penrose, 1903, p. 145; ' Scrivenor, 1906, p. 2; Greig, 1924, p. 12). The main source of monazite in Malaya, as in Burma, probably is the granite. The granite and older rocks are deeply weathered, in places as much as 500 feet deep (Paton, 1958, p. 2—A) and are locally overlain by Tertiary deposits and younger alluvial sediments. Residual de- posits of commercial-grade monazite have been re- ported (Crawford, 1957a, p. 6) from Malaya, but the principal possible commercial source is detrital mona- zite eroded from the granite and older rocks and con- centrated with cassiterite and other heavy minerals in eluvial and alluvial placers (Imp. Inst. [London], Some monazite-bearing tin placers reach great size (Fermor, 1950, p. 82—83). Monazite occurs in the heavy sands (amang) recovered in tin mining. It makes up as much as 50 percent of the heavy sands at Kuala Trengganu (Tringganu) on the east side of Malaya (Eng. and Mining Jour., 1906a). Analyses of monazite from the Malayan tin placers (table 14) show that the amount of Th0; ranges from 3.4 to 9.41 percent (Mining Jour., 1906; Soc. Chem. Industry Jour., 1922) in contrast to the thorium—free monazite found in tin placers in Indonesia (Hintze, 1922, p. 370) and tin veins in Bolivia (Gordon, 1944, p. 330). Although monazite reportedly was not produced as a separate product before World \Var II, Fitch (1952, p. 111) noted that a little monazite probably was re- covered in 1914 from the Sungei Badang in the Gam- bang placer tin field in Pahang. About 1930 some mived concentrates containing monazite were shipped by the Kramat Pulai Co., Ltd. The concentrates con- sisted of scheelite, cassiterite, pyrite, tourmaline, zircon, ilmenite, magnetite, green spinel, garnet, and monazite (Imp. Inst. [London], 1930, p. 366). In 1933 several ASIA 63 TABLE 14.——Chemical analyses, in percent, of monazite from Malayan tin-bearing placers [Analysts: 1, 4. Not given by Krusch (1938, p. 77). 2,3. Johnstone (1914, p. 57). sand having 41.6 percent of monazite and xenotime; 6, recalculated from an analysis of sand containing 23 percent of monazite. 7. Imp. Inst. [London] (1906, p. 306) to be opaque white mona 13 percent; and columbite, 3 percent. 8. Not cited by Wadia (1944, p. 6). 9. 5, 6. Not cited by Imp. Inst. [London] (1906, p. 309); 5, recalculated from an analysis of Johnstone (1914, p. 57). Reported by zite from a concentrate consisting of cassiterite, 65 percent; ilmenite, rutile, and magnetite, 16 percent; monazite, J. Shelton (in Johnstone 1914, p. 57)] 06203 __________________________________ (La, Nd, 130.03 __________________________ (Y, Gd)203 ______________________________ Loss on ignition _________________________________ .94 .52 ________________________ 1: 28 ________ .94 Total _____________________________________ 100. 56 100. 33 3. 5 100. 00 99. 2 99. 85 67. 59 100. 50 1. Bales Tujoh. 6. Bindings. 2. Puchong Babi. River Renting, Perak. 7. Sempan Tin 00., Pahanz. 3. Kulim. Kedah. 8. Malaya (locality not specified). 4. Perak. 9. Kelantan. 5. Sungei Kemaman, Trengganu. J OHORE consignments of black sand from the tin mines were shipped to Japan. In all they amounted to only 250 tons, of which 70—80 percent was ilmenite and the rest a mixture of minerals among which monazite occurred (Willbourn, 1933, p. 5). Beginning in 1935 a market opened for ilmenite, and the great piles of black sand stored from the tin mining began to be processed for ilmenite. The residue from the concen- tration of ilmenite was rich in monazite (Fermor, 1950, p. 96), but monazite as a separate product had not been shipped by 1940 (Harris and Willbourn, 1940, p. 29; Fermor, 1940, p. 80). During 1944 and 1945 the Japanese in Malaya produced 220 tons of monazite and 200 tons of a mixed monazite-zircon concentrate from these residues (Fermor, 1950, table 2; US. Bur. Mines, 1947). A few small shipments of monazite con- centrate containing about 6.0 percent of Tth were said to have been made after 1945 (Davidson, 1956a, p. 203). Reported output of monazite in 1955 and 1956 was 274 short tons and 694 short tons, respectively (Eng. and Mining Jour., 1957, p. 152). Exports of monazite for the period 1951 through 1961 were reported by J. G. Parker (written commun, 1962) to have been as follows: Short ton: Short [M8 1951 _________________ 1957 _________________ 549 1952 _________________ 63 1958 _________ ._ _______ 479 1953 _________________ 208 1959 _________________ 264 1954 _________________ 391 1960 _________________ 47 1955 _________________ 279 1961 _________________ 780 1956 _________________ 707 Water-worn grains of opaque pale-gray and yellow monazite were found at Tingkil (Scrivenor, 1912, p. 3). A considerable amount of monazite is present in the concentrates from the Kambau mines in valley of the Ulu Sungei Payong, a tributary to the Sungei Sedili Besar 4 miles from Sungei Paloi on the China Sea. coast (Willbourn, 1928, p. 27; Scrivenor, 1928, p. 128). These fine—grained concentrates were made by sluicing shallow soil on low hills underlain by granite of Meso- zoic age near a contact between the granite and quartz- iite and shale of Triassic( ?) age. mun Concentrates from tin placers in the valley of the Sungei Karangan near Kulim contained 41 percent of monazite, 39 percent of ilmenite, and 20 percent of cassiterite (Scrivenor, 1912, p. 3; Willbourn, 1925, p. 84). The pure monazite, analyzed about 1911 at the Imperial Institute in London, contained 3.5 percent of Th02 (Scrivenor, 1928, p. 38). Heavy minerals in the placers in the Sungei Karangan are derived from granite intruded into phyllite and sandstone. Tour- maline-bearing aplite is common, and the aplite, gran- ite, phyllite, and sandstone are cut by quartz veins carrying cassiterite, wolframite, and muscovite (Will- bourn, 1926, p. 320). 011 the coast of Kedah and Perlis, monazite is present in sand in the Pulau Lang- kawi (Fermor, 1940, p. 81). 64 THE GEOLOGIC OCCURRENCE OF MONAZITE KELANTAN The monazite richest in thorium oxide in Malaya comes from streams in Kelantan. At an unspecified locality in K'elantan a sample of monazite analyzed by J. Shelton (Johnstone, 1914, p. 57) was found to con- tain 9.41 percent Th02. Scrivener (1931a, p. 17) com— mented that if large quantities of this monazite could be discovered in an accessible locality, there would be a ready sale for it. Of further interest was Paton’s (1958, p. 2—J) statement that the only extensive body of schists in Malaya occurs in northern Kelantan. Does the thorium oxide-rich monazite originate in the schist? NEGRI SEMBILAN Monazite is an accessory mineral in weathered gran- ite or pegmatite exposed at Sungei Betong near Lang- kap (Willbourn, 1925, p. 84; Scrivener, 1931b, p. 24). It forms dull pale-brown crystals having well-defined faces as much as 1 inch across which are weathered on the surface to opaque very pale brown or white. The weathered mineral contains about 6 percent of Th02. Detrital monazite is associated with ilmenite and rutile in cassiterite placers around Seremban (Jarvis. 1947, p. 71). PAHANG The panning of sand from the beds of streams in Malaya was a regular part of the geological surveying there. It was done to determine the distribution of gold and cassiterite. From about 1907 to 1938 brief notes on the mineralogical composition of individual concentrates were published in various annual reports by the Geologist of the Federated Malay States, but as far as the writer knows, no systematic compilations were published. Most of the records on the examina- tion of concentrates collected before 1938 were lost in World War II (Fitch, 1952, p. 51). In 1939, 1940, and 1952 papers were published by J. A. Richardson, E. S. Willbourn, and F. H. Fitch presenting results of systematic studies of the heavy accessory minerals in the rocks, surficial deposits, and alluvium in parts of Pahang and Selangor. In the following review the notes on spot localities published in early reports are mentioned briefly and are followed by summaries of the work of Richardson and Fitch. Monazite accompanied by columbite and xenotime occurs in tin ore from the Ulu Sempam placer area, Pahang (Scrivenor, 1907a, p. 42). The monazite is derived from granite and. contains 8.38 percent of T1102 (Willbourn, 1925, p. 84, 100). North of Bundi on the Sungei Kemaman at the border with Trengganu, cassiterite concentrates have as much as 58 percent of monazite which contains 5.3 percent of Th02 (Scriv- enor, 1907a, p. 42; 1907b, p. 866; 1931a, p. 19). A tributary to the Sungei Kuantan was the source of a monazite-bearing cassiterite concentrate which Scriv- enor (1910, p. 3) viewed as marking an extension of the monazite deposits of the Sungei Kemaman into Pahang. The thorium oxide content of this monazite was 3.15 percent (Willbourn, 1925, p. 84). The mona— zite fraction from a concentrate taken at Gambang near the Sungei Kuantan contained only 0.62 percent of Th02 (Willbourn, 1925, p. 84). An identical value was also given by Willbourn for the amount of thor- ium oxide in monazite separated from a cassiterite con- centrate originating in the Sungei Bisek, a tributary to the Sungei Serau. The analyzed material from Gam- bang may be mainly xenotime instead of monazite, be- cause Fitch (1952, p. 53) described abundant yellow xenotime resembling monazite in the alluvial tin mine at Gambang and showed that it has less than 0.5 per- cent of Th02. Concentrates from Bentong have vari— ously been reported to contain cassiterite, ilmenite, zir- con, garnet, tourmaline, monazite, hornblende, epidote, wolframite, and scheelite (Scrivenor, 1910, p. 3; Will- bourn, 1925, p. 84). Concentrates from the headwaters of the Sungei Lemoi east of the Cameron Highlands are rich in tourmaline, zircon, and ilmenite, have some epidote, leucoxene, monazite, apatite, and topaz, and have sparse to very rare rutile, garnet, and cassiterite (Willbourn, 1932, p. 7). Granite, aplite, and pegma- tite are common in the drainage basins from which the concentrates were taken. Heavy minerals commonly present in surficial de- posits derived from the Main Range granite in the Raub are-a were found by Richardson (1939, p. 80) to be biotite, ilmenite, zircon, apatite, tourmaline, and leucoxene. Less common are pistacite, topaz, chlorite, magnetite, monazite, limonite, and cassiterite. Sparse heavy minerals are rutile including sagenite, anatase, pyrite, and arsenopyrite. A similar but much more re- stricted suite of heavy minerals was obtained from sur- ficial deposits formed on the Gunong Benom Range granite in the Raub area. The suite does not include monazite. It consisted of common biotite, apatite, zir— con, limonite, leucoxene, pyrite, and epidote and very sparse molybdenite. Heavy minerals from surficial deposits formed on mafic and hybrid rocks associated with the Gunong Benom Range pluton in the Raub area are devoid of monazite. They include biotite, amphibole, epidote, apatite, leucoxene, sphene, limonite, chlorite, magnetite, pyroxene, pyrite, chalcopyrite, and allanite. Surficial materials on serpentine give monazite—free concentrates of ilmenite, leucoxene, chromite, picotite, limonite, magnetite, tremolite, pyrite, and pyrrhotite. In the ASIA Raub area the sedimentary rocks contribute to the alluvium only a small amount of heavy minerals. These are ilmenite, leucoxene, limonite, and zircon. Assemblages of heavy minerals in alluvium derived from amphibole schist are barren of monazite and in- clude actinolite, pistacite, zoisite, clinozoisite, tremolite, hornblende, chlorite, pyroxene, ilmenite, leucoxene, lim- onite, garnet, pyrite, and pyrrhotite. Thermally meta- morphosed sedimentary rocks in the aureole adjacent to the Main Range granite give associations of heavy minerals lacking monazite and having biotite, chlorite, rutile, andalusite, chloritoid, tourmaline, garnet, am- phibole, and pyroxene. In the thermal aureole of the Gunong Benom Range pluton, monazite is absent, and biotite, pyroxene, garnet, actinolite, magnetite, tremo- lite, and pyrite are present (Richardson, 1939, p. 80). The Raub area includes a large part of the Malayan gold belt, but gold was not observed in the concen- trates taken from any of the rocks, though it is thought to occur in some of the igneous rocks. Scheelite and cinnabar are also sporadically present in the alluvium but were not discovered in concentrates from the rocks. Monazite is a characteristic mineral of the Main 65 Range granite, is widespread in small amounts, but is unlikely to be of commercial value in the Raub area. Old mine dumps from which monazite could be recon- centrated, as is done elsewhere in Malaya, are not pres- ent in the area (Richardson, 1939, p. 14.4). Fitch (1952, p. 52) prepared 97 concentrates from stream sediments in the vicinity of Kuantan. Two slides of each concentrate were examined under a microscope», and estimates of the relative abundances of the heavy minerals in each concentrate were tabulated. The mineralogical composition of the 27 monazite- bearing concentrates are given in table 15. Concentrates from rivers draining areas underlain by granite consist mainly of ilmenite, colorless pris- matic zircon, cassiterite, tourmaline, and monazite. An- dalusite is rare, and almandine, rutile, and topaz are sporadically present in small amounts. In the Kuantan area, monazite occurs sporadically in the sedimentary rocks of early Carboniferous and Triassic(?) age and in the granites which intrude them. Monazite, however, is absent from the sedimentary rocks where they are dynamically metamorphosed to phyllites or thermally metamorphosed to spotted TABLE 15.—-Mineralogt'cal composition and bedrock sources of monazite-bearing concentrates from streams in the Kuantan area, Pahang, Federation of Malaya [Modified from analyses by Fitch 1952, p. 56, table 4. Symbols used: Ab, absent, P, present; VR, very rare; R, rare; VS, very scarce; S, scarce; 0, common; VG, very common; A, abundant; VA, very abundant; F, flood. without absolute values] Abundanees were estimated without grain counts, and the expressions for abundance were given by Fitch as a general guide Number of Mineralogy of the monazite-bearing samples samples :1) Rocks in the distributive province 3 3 E E3 3 Zircon Location of monazite- q'; an a; '8 : .... 6'; 3 :_. bearing sample (river) 2-5 ’5, g 3 g <5 2: c g; a, N a ., Other 2 s s v s e a e s a a a .. E s g. minerals o n o g. a E E a E .5 E E ‘3' 3 E 5 E 2 <: O 0 <5 : E m e a B 94 Granite at Ulu Sungei Reman ______________ 1 VC VS ______ Xenotime P-.. Anak Sungei Chereh. Granite at Sungei Bakah ...... . VA VR _ ___________ __ Sungei Anak Reman. Do __________________ . 4 VC R _ Sungei Roman. Do..- _ VC VR . Anal: Sungei Reman.. Do ______________________________________ A R . .._ Ulu Sungei Roman. North and east sides of granite at Gambang. R S _ . Pyrite VR. .._ Sungei Sangka Dua. Do ______________________________________ R VA ______ Xenotlme P... Anal: Sungei Pan- e mg. Do-- 7 S C ______ Xenotime P... Do. Do R C ...... Xenotime P... Do. Do R R ...... Xenotime P--. Do. Do 0 R ._- ________________ Ulu Sungei Pandan. Do . ' Do. South Side of granite at Gambang ................. { }Sungei Tulang. Do ______________________________________ 5 Sungei Belat. Do.. __ Sungei Badang. Do._ __ Do. Do ____________________ ._ Sungei Gambang. Granite at Bukit Beserah. -__ 0 __ ........... Not specified. Granite at Bukit Ketam ____________________ 1 0 VC ______ R VR R ______ Xenotime P-.. Anak Sungei Long- Sedimentary and metamorphosed sedimen- 1 tary rocks of Lower Carboniferous age (no granite). Sedimentary and metamorphosed sedimen- 0 tary rocks of Triassic(?) age (no granite). Granite and sedimentary rocks (Lower Carboniferous) . 3 Do ...................................... Do ______________________________________ Granite and sedimentary rocks (Triassic(?) ' 5 kang. Xenotirne P-.. Anak Sungei Roman. Not specified. Anak Sungei Chara. Do. Do. Anak Sungei Taweh. Do. Sungei Taweh. Do. Do. 238—813——67-——6 66 slate or schist in the aureoles of the granite plutons. The apparent abundance of monazite in the granites increases as the abundance of the iron minerals and garnet decreases in the concentrate. This feature probably reflects the variation in ilmenite, magnetite, and garnet more than it does an absolute change in the abundance of the monazite. Xenotime is very common in concentrates from the granite at Gambang. In places it makes up as much as 60 percent of the concentrate. It is yellow and closely resembles monazite. A partial analysis showed the following characteristic components of xenotime (Fitch, 1952, p. 53): Percent U303 _____________________________________ 0. 94 Th02 _____________________________________ . 5— Y203 (group) ______________________________ 57. 1 The granite at Ulu Sungei Reman is noteworthy for the presence of topaz and greisen and the abun- dance of tourmaline, but it is very poor in monazite (Fitch, 1952, p. 21). Onlyl concentrate of 13 is monazite bearing, and that one has the least amount of tourmaline. PERAK The first recorded discovery of monazite in crystal— line rocks in Malaya was said by Scrivenor (1915, p. 2; 1928, p. 143; 1931b, p. 25) to have been made at a quarry south of Lenggong in northern Perak (Metal Industry, 1917). The actual date of discovery was not given. The quarry exposes a contact between a pegmatite dike and crystalline limestone. Large quan- tities of rock at the contact were collected, crushed, and panned; and the concentrate contained slightly hydrated and opaque monazite accompanied by either zircon or xenotime. Scrivenor thought the concentrate came from the pegmatite, but he did not exclude the possibility that a small amount of the monazite may have come from the limestone. Monazite occurs in detrital tin concentrates in crev- ices between residual limestone pinnacles at Siak near Siputeh (Scrivenor, 1907a, p. 37; Imp. Inst. [London], 1911b) . The monazite is not uncommon, and it is asso- ciated with cassiterite, zircon, rutile, brookite, pyrite, arsenopyrite, ilmenite, muscovite, and apatite. Stock- works of small veins in the limestone pinnacles are im- pregnated with crystals of cassiterite, fluorite, arseno- pyrite, quartz, calcite, muscovite, and tremolite; but monazite is not present. Thus, the detrital concen- trates between the limestone pinnacles contain minerals absent from the stockworks, but the source of these other minerals, including the monazite, was not re- ported (Scrivener, 1907b, p. 843). Monazite from the placer worked by the Malayan Tin Dredging Co. at Batu Gajah contains 6.5 percent THE GEOLOGIC OCCURRENCE OF MONAZITE of T1102 (Scrivener, 1920, p. 5; Willbourn, 1925, p. 84). A few of many concentrates from the Sungei Siput area are monazite bearing. Principal minerals in con- centrates from the J along Tinggi Estate, Sungei Terjol, and Sungei Tekuah are, in order of decreasing abundance, ilmenite, zircon, tourmaline, epidote, spinel, and garnet. Locally grains of monazite, pyrite, cassi- terite, anatase, topaz, zoisite, hornblende, andalusite, and rutile occur. Black sand from tin placers at Baias Tujoh (Bajas Tujoh, Bias Tujoh, Bajas Puchab) in the Kampar district have 1.5 percent of monazite, and the monazite contained 4—5 percent of Th02 (Imp. Inst. [London], 1911b; Willbourn, 1925, p. 84). Monazite occurs in granite and aplite at the scheelite mine of Kramat Pulai Tin, Ltd., in the Kinta valley at the village of Pulai 6.5 miles southeast of Ipoh. The geology of the mine was described in detail by Will- bourn and Ingham (1933). Relations of the monazite have been summarized from that account. The mine is in a natural amphitheatre carved in limestone where a band of schist 100 feet thick is inter- layered with the limestone. The floor of the amphi- theatre is a pavement on limestone eroded smooth by the sea and later dissected by streams and buried under cassiterite-bearing alluvium. The mine is near a con— tact between limestone and granite on the east side of the Kinta valley. The monazite-bearing granite and aplite are part of the Main Range granite batholith. _ Orthoclase, microcline, quartz, and a little plagio- clase, zinnwaldite, and biotite make up the granite. Accessory minerals are abundant zircon; sparse, but uniformly distributed, monazite; and scarce tourma- line, rutile, topaz, cassiterite, sphene, and thorotung- stite. At the contact of the granite near the scheelite mine, there is more aplite than granite, and the aplite generally forms plutonic margins, although dikes of aplite are common in the granite. The aplite consists of feldspars and micas like those in the granite, and it contains accessory tourmaline, topaz, zircon, monazite, anatase, apatite, and cassiterite. Monazite is more abundant in the granite than in the aplite, and topaz is more abundant in the aplite than in the granite. Monazite is not present in the limestone, which has been metamorphosed to marble. It is apparently also absent from the layer of schist although the schist con- tains cassiterite and topaz. The schist was formed from alternate layers of calcareous sand and silt which underwent crushing and thermal metamorphism. The schist consists of layers of pyroxene schist, biotite-mus- covite-quartz-schist, andalusite-biotite-muscovite schist, and hornblende—pyroxene schist. The aplite grades along strike into pegmatite dikes in which book muscovite is common and crystals of ASIA beryl and tourmaline are present. These pegmatites are cut by quartz veins which contain a little wolfram- ite. No descriptions of accessory minerals in the peg- matite of the dikes were given. Both schist and lime— stone have contact zones along the walls of the aplite and pegmatite dikes; monazite was not mentioned as one of the minerals in the zones, although cassiterite is present. The scheelite ore is a coarse—grained pegmatitic in- tergrowth of fluorite and scheelite in the limestone and schist. In the schist it contains a very small amount of quartz and pale-green mica. The ore contains no zircon, rutile, and monazite as observed in the granite and aplite, and was regarded by Willbourn and In- gham (1933, p. 472) as a low-temperature deposit. Deposition of the scheelite at low temperature is at— tributed to the presence of abundant fluorine. Appar- ently the monazite crystallized before the commence- ment of the late-stage mineralization. Some years before Willbourn and Ingham studied the geology of this deposit near Ipoh, Scrivenor (1911, p. 2) described a concentrate from an unknown local- ity near Ipoh as containing 88.4 percent of columbite, 11.6 percent of cassiterite, and a few grains each of zircon, tourmaline, hematite, and monazite. Other localities reported to be sources of monazite- bearing concentrates in Perak are Selama, Sungei Kenering (Kenring River) at Puchong Babi, the Sri Muka, Batang Padang, Rotan Dahan, and Papan (Imp. Inst. [London], 1911b). SELANGOR Monazite is a minor accessory mineral in the three varieties of granite in the Main Range in east-central Selangor (Willbourn, 1940, p. 39). Relative abund- ances of the accessory minerals were determined in 10 concentrates from each variety of granite. In decreas- ing order of abundance, the accessory minerals in coarse-grained porphyritic biotite granite are magne- tite, tourmaline, zircon, fluorite, cassiterite, topaz, monazite, apatite, sericite, muscovite, epidote, clino- zoisite, zoisite, pyrite, anatase, and andalusite; and accessory minerals in porphyritic epidote granite are magnetite, apatite, zircon, pyrite, muscovite, monazite, cassiterite, allanite, and tourmaline. Also in order of decreasing abundance, the accessory minerals in fine- grained tourmaline granite are fluorite, cassiterite, topaz, apatite, zircon, pyrite, muscovite, monazite, ana- tase, sericite, and andalusite. In total abundance of accessory minerals, the coarse-grained porphyritic bio- tite granite contained twice as much as the porphyritic epidote granite and four times as much as the fine- grained tourmaline granite. 67 Dynamically metamorphosed sedimentary rocks southwest of the granite contain no monazite (Will- bourn, 1940, p. 35—36). Streams along the edge of the Kuala Selangor swamps in the vicinity of Bukit Ginting Prah contain a very small amount of cassiter- ite, zircon, tourmaline, ilmenite, magnetite, anatase, and monazite (Willbourn, 1940, p. 44). TRENGGANU Small amounts of monazite were reported to be ob- tainable from most, if not all, tin placers in Trengganu (Scrivenor, 1928, p. 143—144; 1931a, p. 19; Millington, 1928, p. 6). The reported occurrences are on the Sungei Kemaman; and, because that river forms the boundary between Trengganu and Pahang, the few descriptions were cited for Pahang in some of the literature. INDIA The largest monazite deposits in the world are the readily accessible placers in beach, bar, and dune sands along the west and east coasts of India (Wadia, 1950, p. 157; Imp. Inst. [London], 1933b, p. 379). Monazite was discovered in India in 1909 by C. W. Schomberg in sand along the Kerala and Madras (Travancore—Cochin) sector of the Malabar coast be— tween Cape Comorin at the southwest tip of India and Quilon (in Krishnan, 1951, p. 298; in Brown and Dey, 1955, p. 279). Subsequent exploration exposed mona- zite placers, commonly near the mouths of streams, scattered northwestward along the west coast from Cape Comorin to the estuary of the Narbada River on the Gujarat coast west of Amod (Broach) (Wadia, 1956, p. 164). The most recent discoveries are the deposits at Ratnagiri, at Mormugao (Marmagoa), and along the Gulf of Cambay south of the Narbada. In- vestigations on the east coast of India disclosed mona- zite placers, possibly richer than those of the west coast, along the Madras shore from Cape Comorin northeastward at least as far beyond the Coromandel coast as Chilka Lake and the mouth of the Brahmani River in Orissa (Wadia, 1956, fig. 1). Other sites where monazite has been found on the east coast are Visakhapatnam, the mouths of the Godavari River, the vicinity of Negapattinam, and the vicinity of Tin- nevelly (Tirunelveli) on the Gulf of Mannar. The monazite in the beach placers along the south- west coast is concentrated with ilmenite, rutile, zircon, sillimanite, and garnet (Brown and Dey, 1955, p. 241). The heavy minerals are transported from inland to the sea by rivers, or they are deposited in the sea by the erosion of the coastal Warkilli (Varkala, Varkkal- lai, Warkalay) series of sedimentary rocks of Tertiary age (Chacko, 1917, p. 2). The Warkilli series overlies 68 plutonic metamorphic rocks—mostly charnockite, lep- tynite, cordierite gneisses, biotite schist and gneiss, hornblende schist and gneiss, diorite, granite, and peg- matite~which are exposed in the Western Ghats and Mysore and which are the ultimate source of the mona- zite in both the Tertiary sediments and the present beaches. The plutonic rocks of the Western Ghats and similar rocks in the interior of the peninsula prob- ably are the source of the heavy minerals at Ratnagiri and Mormugao. Metamorphic and igneous rocks in the interior are the source of the monazite in the estu- ary of the Narbada River (Wadia, 1956, p. 166). Monazite in placers along the east coast probably is derived from sillimanitic granulites in Madras and Orissa. An extension of these granulites is exposed in Ceylon and is the main source of monazite in placers on that island. Monazite has not been commercially produced from the crystalline rocks of India. Indeed, as late as 1956 no primary deposit of adequate size and tenor for mining was known, although monazite-bearing garneti- ferous biotite schist containing more than 17.9 percent of monazite was known in Travancore (Davidson, 1956a, p. 205—206). This rock is in a migmatite zone at Tadikarakonam (Thadikarenkonam). Exposures are poor, but the monazite-rich parts of the migmatite were thought by Davidson to be 100 feet wide and to extend intermittently along strike for nearly a mile. Davidson (1956a, p. 206) estimated that the deposit might yield 100—200 tons of thorium per foot of depth from monazite which contains 10.7 percent of ThOz. In 1956, the plans of the Rare Minerals Survey Division of the Indian Atomic Energy Commission included studies of the distribution of primary sources of mona- zite (Wadia, 1956, p. 166). The commercial sources of monazite are the beach placers. Between the time mining began in 1911, when 932 short tons of monazite was produced until 1961, a total of nearly 100,000 short tons was produced. Peak output was 5,848 short tons in 1938. Reserves of placer monazite in India were conserva- tively estimated by Wadia (1956, p. 164) to be 2 mil- lion tons. The resources in monazite must be many times as great as the estimated reserves because the monazite has been considered as a source of phosphate for fertilizer (Kartha, 1955, p. 53; Nair and Moosath, 1955, p. 63). CRYSTALLINE ROCKS Few descriptions of the occurrence of monazite in the crystalline rocks of India were found by the writer. A summary of the data follows. KERALA A thorium-rich mineral having monazite structure THE GEOLOGIC OCCURRENCE OF MONAZITE occurs in pegmatite in granite gneiss at Kuttakuzhi about 23 miles east—southeast of Trivandrum near the border with Madras. The mineral, which was named cheralite by Bowie and Home (1952, p. 2), has a specific gravity of 5.28 and has the following composition: [Analystz Radiochem. Div., Chem. Research Lab., Teddington, England (in Bowie and Home, 1952, p. 2)] Percent Percent 0e20, _______________ 14. 21 A1203 ________________ Trace Lagos (group) _________ 13. 35 Fe203 ________________ Trace Y203 (group) ______________ CaO _________________ 6. 30 Th0; ________________ 31. 50 PbO_______l _________ .92 U303 _________________ 4. 05 H20+ _______________ . 06 P205 _________________ 26. 80 SiOz _________________ 2. 10 Total __________ 99. 29 In 1914, a thorium-rich material similar to cheralite was collected from Cootykad Pothay in Vilavancod Taluk near the locality where the cheralite was later discovered (Brown and Dey, 1955, p. 278). Monazite from graphite—rich pegmatite in the Vel— lanad (Vellanaud) graphite mine, Travencore, con- tains 6.0 percent of Th02 . Monazite from quartz peg- matite and mica pegmatite at Esanthimangalam in the Thovala Taluk was analyzed by Venkitachalam Iyer who found 9.2 and 8.7 percent of Th02, respectively (in Chacko, 1917, p. 8; in La Touche, 1918, p. 391). Monazite was also reported in graphite-bearing peg- matite at Tadikarakonam about 14 miles northwest of Nagarcoll (Mining J our., 1911). This pegmatite is in charnockite and leptynite. Pegmatites containing monazite and zircon have been reported at Kalkulam Taluk (Mining J our., 1947a) . MYSORE An often described, deeply weathered pegmatite dike exposed about 200 yards west of the 3/ 5 furlong stone near Yadiur (Yediyoor, Yedur, Yediyur) on the road from Bangalore to Kankanhalli was discovered to be monazite bearing by L. Subba Rao in 1912, and min- ing was begun for monazite in 1916—17 by V. S. S. Iyer of the Geological Department of Mysore State (Memminger, 1917a; Sen, 1935, p. 30; Ramaswamy, 1945, p. 81). The pegmatite is about 25 feet thick. It has well-defined zones consisting of a wall zone, intermediate zones, and quartz core. It is emplaced in granitic gneiss that contains xenoliths of greenstone. Other pegmatite dikes and veins of aplite cut the gneiss. Monazite in the pegmatite is reddish brown, has a resinous luster, and occurs sporadically. Rela- tions of the monazite to the zones in the dike have not been described in detail, but apparently it occurs both with beryl in the quartz core (Rama Rao, 1942, p. 175) and with feldspar, quartz, muscovite, sam- arskite, and columbite in other zones (Ramaswamy, ASIA 1945, p. 81—82). By 1917, mining for monazite was halted because the quantity was small and the tenor of the monazite in ThO2 was only 2.25 percent (Smeeth and Iyengar, 1916, p. 191—192; Memminger, 1917b). In 1941, mining of the dike for beryl began, and the monazite was again reported to be too sparse to be economic (Rama Rao, 1942, p. 180). A chemical anal— ysis of the monazite was made by the Chemical Re- search Laboratory in Teddington, England, and the results, in percent, given by Arthur Holmes (1955, p. 85) were 3.91 for Th02, 0.22 for U303, and 0.38 for PhD. This monazite from Yadiur has a Th/U ratio that is nearly 50 times greater than the ratio of 0.37 deter- mined by Aithal (1955, p. 523) for monazite from an unspecified pegmatite in Mysore. Quart-zose gneiss on the west side of the Kolar schists near the Bangarapet (Bowringpet) Road contains vis- ible red monazite, but the monazite is uncommon (Smeeth and Iyengar, 1916, p. 191—192; Memminger, 1917b). Considerable prospecting for monazite was done about 1916—17 along streams in the Kadur and Hassan districts of Mysore and elsewhere in areas underlain by charnockites. Small amounts of monazite were found in several places, but economic deposits were not discovered (Memminger, 1917b). ANDHRA rnannsn Lit-par-lit veins of pegmatite and lenticular masses of pegmatite in sillimanite gneisses underlying the red loam of the Waltair Highlands in the Visakhapatnam (Vizagapatam) district contain monazite and zircon (Mahadevan and Sathapathi, 1948). The pegmatite veins consist of gray, pink, and white feldspars, white and blue quartz, biotite, iron-bearing minerals, zircon, and two varieties of monazite. One variety of mona- zite is greenish yellow; the other is dark green and has a submetallic luster. Heavy minerals from two samples of mafic charnock- ite, one sample each of intermediate and silicic char- nockite, and two samples of leptynite from the hills near Padmanabham about 10 miles from Bhimilipatam in the Visakhapatnam district were studied by Sastry (1954). The total amount of heavy minerals was greatest in the more mafic charnockite, decreased in the intermediate and silicic charnockite, and was least in the leptynite. Monazite was present only in the leptynite (table 16). 31mm Pegmatites in the Gaya district have been the source of several specimens of monazite used for partial or complete chemical analyses. A complete analysis made by Sarkar showed the following amount of 69 TABLE 16.—Heavy minerals, in percent, in charnockite and leptynite from Visakhapatnam, Andhra Pradesh, India [Analyst Sastry (1954, p. 151). Symbol used: _._., absent] Charnockite Leptynite Mafic Inter Silicic mediate Zircon ________________________ 2.0 1. 7 3.0 6. 3 4. 7 6.0 Apatite ______________ 1. 3 1.7 7. 3 4. 7 3.0 3. 3 Sphene ........... 1. 7 1. 3 __________ 2. 7 3. 3 3. 7 Monazite ___________________________________________ 2. 0 2. 3 Hypersthene. __ __ 44.0 45.0 58 0 75. 3 27.7 36.0 Hotnblende. _ _ 11. 3 19. 3 __________________________________ Diopside _________ 28. 7 23. 3 .................................. Garnet ........................... 25 3 6.3 32.2 25.7 Sillimanite. . _ _ _ __________________________________ 6. 9 5. 7 Biotite _______________________ 2.0 2.3 4 7 2.7 11.3 8.7 Opaque minerals _____________ 9.0 5. 4 1 7 2.0 8.9 8. 6 thorium oxide in monazite having a specific gravity of 5.16 from mica pegmatite at Singar in the Gaya dis— trict (Holmes, Arthur, 1949a, p. 297; 1949b, p. 20; 1950, p. 21; 1955, p. 92—93; Palache and others, 1951, p. 694): [Analystz Sarkar (1941, p. 247)] Percent Percent Ce203 _____________ 22. 00 030 ______________ 0. 83 (La, Nd, Pr)203__ __ 32. 72 MgO _____________ . 09 Yan ______________ 1. 15 MnO _____________ Trace Th02 _____________ 12. 00 PbO ______________ . 5331 U303 _____________ . 2677 C ________________ Trace P205 ______________ 27. 22 1120— ____________ . 15 SiOz ______________ 1. 56 H20+ ____________ 48 A1203 _____________ 1. 20 -——-- Fe203 _____________ . 44 Total _______ 100. 64 At Pichhli in the Gaya district, monazite containing 9.95 percent of Th02 is associated with pitchblende, torbernite, autunite, apatite, and columbite in a peg- matite in garnetiferous mica schist (Tipper, 1919, p. 259—260). Small amounts of monazite and zircon occur in pink gneiss about a mile east of Bangaikalan in the Hazaribagh district (Krishnan, 1958, p. 135). RAJASTHAN Arthur Holmes (1949a, p. 293) reported that a muscovite pegmatite of post—Delhi age at Soniand (Soniana) was formerly mined for monazite. The locality was shown by Gupta (1934, pl. 21, p. 152) to be in a band of gray micaceous phyllite locally containing garnetiferous schist of the Aravalli system. An analysis by A. A. Smales showed the monazite to be very rich in thorium oxide (Holmes, Arthur, 1949a, p. 294; 1949b, p. 19; 1955, p. 96): Percent Th0; _____________________________________ 18. 75 U303 _____________________________________ . 79 PhD _____________________________________ . 567 CONSOLIDATED SE’D‘IMENTARY ROCKS Monazite—bearing sandstone and lignite in the VVar- killi Series of Tertiary age are exposed between Vark- kalli and Anjengo on the Malabar coast. Ash from 70 the lignite contains monazite (Masillamani and Chacko, 1913, p. 699). Beach placers in the area have concentrated monazite and other heavy minerals re- leased by the erosion of the sandstone. Yellowish-brown ovoidal grains of monazite are present, but very sparse, in red and yellow ocher and white clay in laterite in the Sohawal area of Madhya Pradesh (Sharma and Purkayastha, 1934). The white clay and red and yellow ochers form fine laminae in laterite which caps hills underlain by sandstone. At places the laterite is indistinctly stratified and more or less clastic, but no fragments of the underlying sand- stone are found in the laterite. The white clay and the ochers contain almost identical assemblages of heavy minerals, but the assemblages are different from those in the sandstone (table 17). Presumably the rocks from which the clay and ochers formed are different from the sandstone, but their original character is not known. TABLE 17.——Heavy minerals in clay, ocher, and sandstone in Madhya Pradesh, India [Modified from Sharma and Purkayastha (1934, p. 50). Symbols used: A, abundant; V0,] very common; C. common; S, scarce; VS, very scarce; R, rare; VR, very rare White Red Yellow Upper Upper clay ocher ocher Bhander Rewah sandstone sandstone Magnetite and ilmen- C A A VC C ite. Tourmaline __________ VC S S VS VS Zircon _______________ VC C C VS VS Kyanite _____________ VR VS VS ________________ Staurolite ____________ VS C C ________________ Rutile _______________ S S R VR ________ Garnet ______________ VR VR VR VR VR Andalusite _________________ VR ______________________ Fluorite(?) _ - Monazite- _ _ Zoisite _____ Chloritoid ___________ R VR VR VR VR Muscovite ___________ VR R ______ S ________ Hornblende, green _______________________ VR ________ FLUVIAL PLACERS Fluvial placers from which monazite and other com- mercially useful minerals could be recovered econom- ically probably exist in India, but none has been mined. Wadia (1956, p. 166) prepared estimates of the amount of thorium available in India which show fluvial plac— ers as a possible source for small amounts of monazite even though they have lower concentrations of mona- zite than the beach placers. Few monazite-bearing stream deposits have been described. Stream concentrates from Idar in central India were said by Tipper (1914, p. 195) to have a little monazite. Many streams in Mysore have been sampled, and lo- cally monazite was found, but no commercial alluvial deposits were discovered (Smeeth and Iyengar, 1916, THE GEOLOGIC OCCURRENCE OF MONAZITE p. 191—192). A deposit of ilmenite, monazite, and zir- con in Andhra Pradesh about 45 miles northeast of the railroad between Nander and Nizambad was shown by Wadia (1950, p. 158—159) on a map of the mineral localities of India. The kind of deposit was not spe- cified, but the assemblage of minerals is typical of placers. Streams flowing from the Waltair Highlands to the coast of Andhra Pradesh are monazite bearing (Mahadevan and Sathapathi, 1948). Large alluvial deposits of monazite associated with ilmenite, rutile, sillimanite, columbite, tantalite, and magnetite were f0und in the late 1950’s in the Purulia district in Bihar and the Ranchi district in West Bengal (US. Bur. Mines, 1959). About 12 miles northwest of Purulia in the vicinity of Kataholdih, monazite-rich sand is as thick as 10 feet and has an average thickness over an area of 5 square miles of slightly less than 3 feet. BEACH PLACERS The commercial monazite deposits of India are nat- ural concentrations of monazite with ilmenite, rutile, zircon, sillimanite, and garnet in the beach placers. At favorable localities, tidal currents and waves selec- tively remove minerals of low specific gravity and leave behind minerals of high specific gravity. Concentra- tions in which monazite is as much as 46 percent of the beach sand have been observed on the Travancore coast (Imp. Inst. [London], 1911a, p. 103), but ordinarily the monazite makes up less than 10 percent of the beach sand, possibly about 2—3 percent of the raw sand (Wadia, 1956, p. 164; Brown and Dey, 1955, p. 278; Kartha, 1955, p. 53). The raw black sand, however, contains 50—90 percent of ilmenite, an amount that ex- ceeds any other yet discovered (Brown and Dey, 1955, p. 241; Gillson, 1957, p. 554; Hess, 1937a, p. 902—903). Concentrates processed from the black sand have 3—30 percent of monazite (Imp. Inst. [London], 1935b, p. 356). Sand dunes near the Travancore coast contain monazite and at places are mined with the beach plac- ers. Locally the dunes are cemented by calcium carbo- nate into compact masses. Other monazite-bearing cemented sedimentary rocks exposed along parts of the Travancore coast are the ferruginous grits of the Warkilli Series (Tipper, 1914). KERALA Monazite was discovered in the Travancore—Cochin sector of Kerala and Madras in 1909 by C. W. Schom- berg. For many years monazite was mined from the beach around Manavalakurichi between the old port of Colachel and the lighthouse on the point at Muttam (Viswanathan, 1946, p. 22—24). In 1933, mining shifted to deposits north of Neendakara (Nindakara) 6 miles ASIA 71 north of Quilon. Commercial minerals that were ex- ploited include monazite since 1911, ilmenite and zircon since 1922, garnet and sillimanite since 1936, and rutile since 1939. Baddeleyite was discovered in 1936 in the sands at Manavalakurichi, but commercially feasible separation was not possible as of 1962. In order of decreasing abundance, the heavy minerals in the beach sand are ilmenite (80 percent), zircon, sillimanite, rutile, monazite, and garnet. The heavy minerals are reconcentrated by wave, cur- rent, and wind action in barrier bars, beaches, and dunes from sediments transported to the coast by rivers that drain the Warkilli Series of sedimentary rocks. The largest of these streams, the Kallada River, empties into Ashtamudi Lake, which is separated from the Arabian Sea by the Neendakara Bar. The rocks of the Warkilli Series are intermediate host rocks for monazite between the original source rocks and the beach placers in the Quilon area, but at Cape Comorin the monazite was said to come from direct disintegration of gneiss (Masillamani and Chacko, 1913, p. 699). In the literature analyses commonly list the amount of thorium oxide in monazite from the Kerala coast, but few analyses give the abundances of the rare earths. The amount of thorium oxide in fine-grained monazite has been reported from 15 beach placers, and it has been determined in monazite from 3 subaerial detrital deposits from Kerala. The results of these analyses together with the abundance of the monazite in concentrates from the beaches are given in table 18. Partial analyses of monazite from the beaches made by W. A. K. Christie showed 1.55 percent of SiO2 and 6.0 percent of Th02 in handpicked material and 8.5 and 10.08 percent of ThOZ in magnetically separated TA-BLE 18.—Abundance of monazite and amount of thorium oxide tn the monazite, 1n percent, in ilmem'te concentrates from beach placers on the Malabar coast of Kerala and Madras, I ndta [Anal ses: 1—2, by Imp. Inst. [London] (1911. p. 103-105); 3-15, by Imp. Inst. [Lon- don (1935b, p. 355—356); 16—18, Venkitachalam Iyer (in Chaeko, 1917, p. 1—17). Symbol used: n.d., no data] Monazlte Th0: Beach near Qullon __________________________________ DU _. P509S989?9°9°P'!°S° sn- - n—a ?‘:‘:“9°5°5°?°9°9°?°?°>’.°°>‘9° 9"?°° ..... 0.__._.,_....________.____..____._._.._...__.._ Beach, 7th milestone on road from Quilon to Cha- vars. _.. Neendakara. north of bar _______________ . Neendakara, south of bar. _ -_. Tiruvellauram ____________ .._ Varkkalli ........... - Kurumbantura _____ Hw _.. Pudur _____________________________________ _ Manavalakurichl, mouth or Valllar Rive Muttam ............................. Cape Comorin ....................... _ Leepuram (Muttamtura). _ __ -._ -.. Leepuram (near lighthouse) ............. . Subaerial detrital monazite, Travancore e°°asaasasasasa see FF? samples of monazite (Chem. Trade Jour. and Chem. Engineer, 1915). A partial analysis showing 0.35 percent of U308 and 9.78 percent of Th02 in monazite from beach sand in Kerala was made by the Chemical Research Laboratory in Teddington, England (Holmes, Arthur, 1955, p. 102). A partial analysis of detrital monazite from the Kerala coast made by Kartha (1955, p. 54) disclosed the following composition: Percent RE203 _____________________________________ 61. 73 Th0; ______________________________________ 8. 73 P205 ______________________________________ 27. 00 Insoluble residues ___________________________ 1. 40 Analyses showing the rare earths and thorium oxide in two samples of Kerala placer monazite were given by Johnstone (1914, p. 57; Imp. Inst. [London], 1914a, p. 57): Percent 08203 ___________________________________ 31. 90 Lagos (group) ____________________________ 28.00 i 61' 11 Y203 ___________________________________ . 46 . 62 Th02-..__-__-____-___-_________-____--__- 10.22 8.65 U303 ___________________________________ . 37 _______ P205 ___________________________________ 26. 82 26. 50 SiOg ____________________________________ . 90 1. 00 A1203 ___________________________________ . 17 . 12 F8203 ___________________________________ 1. 50 1. 09 Geo ___________________________________ . 20 . 13 Loss on ignition _________________________ . 46 . 45 Total _____________________________ 101. 00 99. 67 According to Kremers (1958, p. 2), the average com- mercial monazite from Kerala contains 59.5 percent of R1320. and 8.5 percent of Th02. A complete analysis of the rare earth and thorium oxide precipitate from placer monazite from Kerala was published by Murata, Rose, and Carron (1953, p. 294). Their published analysis showed that the sum of the rare earths plus thorium oxide was equal to 100.6 percent of the precipitate. The precipitate equaled 67.82 percent of the monazite (K. J. Murata, H. J. Rose, Jr., and M K. Carron, oral commun, 1958). If the precipitate is recalculated to equal 67 .82 percent, the composition is as follows: Percent Lao. ______________________________________ 12. 94 Geo; ______________________________________ 28. 31 Prison _____________________________________ 3. 44 Nd203 _____________________________________ 12. O7 Sm203 _____________________________________ 1. 89 Gdgoa _____________________________________ . 54 Y203 ______________________________________ . 27 Th0, ______________________________________ 8. 36 Total ________________________________ 67. 82 72 The average value of thorium oxide in the 26 listed analyses of monazite from the Malabar coast of Kerala and Madras is 8.1 percent. If the three lowest values (the analyses of subaerial detrital monazite) are omitted, the average abundance of ThOz in this mona- zite is 8.5 percent, which is the value given by Kremers (1958, p. 2) for commercial monazite from Kerala. This average is more realistic than the average of 7 percent of Th02 suggested by Krusch (1938, p. 75), or the average of 9—10 percent of Th02 quoted by Nag, Das, and Dasgupta (1944, p. 169), or the 10 percent mentioned by Petar (1935, p. 16). Few of these analyses show the abundance of uranium in monazite from India, but even these few are adequate to show that the detrital monazite on the beaches is not unusually rich in uranium. The pub— lished analyses show that the monazite contains 0.2—0.46 percent of U303 (Wadia, 1956, p. 164). In 1911, seven monazite deposits between Cape Comorin and Quilon were estimated to contain at least 18,000 tons of monazite (Mining J our., 1911). By 1960, nearly 100,000 tons of monazite had been recovered, and estimates of the probable reserves of monazite in Tra- vancore had reached 1.2 million tons (Grund, 1956, p. 1547). Reserves of thorium in monazite placers along the west coast of India and in the alluvial deposits were estimated to be 500,000 tons (Mining World, 1959, p. 85). GUJARAT Recent discoveries show that monazite in coastal deposits extends northwest to the estuary of the Narbada River on the Gujarat coast of India (Wadia, 1956, p. 164). Apparently, the source of the monazite in the most northwesterly deposits is plutonic rocks upstream on the Narbada to the northeast of the THE GEOLOGIC OCCURRENCE OF MONAZITE Deccan trap and the Delhi and Aravalli belts north of the Gulf of Cambay. Original analyses of monazite from the Gujarat coast are lacking, but the monazite was reported to have from 5 to 11 percent of ThOz (Wadia, 1956, p. 164; Canadian Mining J our., 1955) . MADRAS AND ANDHRA PRADESH Monazite placers possibly richer than those of Kerala have formed along the Madras coast northeastward from Cape Comorin to the border with Orissa (Mining J our., 1947b; Wadia, 1956, fig. 1). The principal localities in Madras and Andhra Pradesh are the coast at the Gulf of Mannar, Negapattinam, the mouths of the Godavari River, and the area at and north of Visakhapatnam (Vizagapatam). The deposits at Visakhapatnam have been studied more than the others. At Visakhapatnam the bedrock in the hills adjacent to the coast is composed of garnetiferous sillimanite gneiss and quartzite of the khondalites, charnockites, leptynites, and also of pegmatite. Overlying these rocks is red loam (Mahadevan and Sathapathi, 1948; Rao and Chetty, 1955, p. 493). Short streams that are rich in black sand lead from the hills to the coast. Monazite on the beaches is invariably associated with ilmenite and magnetite, and, according to the pioneering studies of Mahadevan and Sathapathi, is derived principally from pegmatites in sillimanite gneisses. Anjaneyulu (1953, p. 95) noted that these gneisses are an important source of monazite and showed that the proportion of monazite in the beach sand increases as the abundance of magnetite, ilmenite, and zircon increases (table 19). South of Visakhapatnam the beaches have been studied to the vicinity of Pudimadaka (Anjaneyulu, 1953, p. 89—94). They range in width from 50 to TABLE 19.—Mz'neralogical composition, in percent, of black sands from streams, dunes, and beaches between Errada and Pudimadaka, India [Modified from Anjaneyulu (1953, p. 96)] 1 2 3 4 5 6 7 s 9 10 Heavy minerals ______ percent _____ 73. 88 63. 57 27. 79 50. 83 67. 68 70. 07 72. 38 68 04 38 15 21. 28 Magnetite ______________________ 51. 62 42. 26 17. 17 31. 86 20. 32 50. 67 50. 02 49. 23 20. 52 7. 56 Ilmenite ________________________ 7. 03 8. 16 4. 33 6. 49 7. 12 7. 48 4. 27 8. 65 7. 77 3. 85 Garnet: ________________________ 8 40 4 79 2. 72 8. 62 35. 40 5. 00 l. 83 4. 17 3. 02 7. 37 Monaz1te _______________________ 2. 03 1 40 . 36 . 67 . 27 1. 12 . 09 . 33 . 57 . 09 ercgn _________________________ 2. 16 2 60 . 55 84 . 42 l. 79 . 79 1. 48 1. 17 13 Rutileu' _______________________ .69 96 . 13 4s . 37 . 91 .67 . 21 .65 07 Slllimanite ______________________ . 47 2. 28 . 93 75 . 11 1. 35 8. 74 . 24 . 92 23 Hypersthene ____________________ . 19 . 15 . 47 17 . 85 . l5 5. 62 2. 90 l. 91 16 Hornblende _____________________ . 28 . 55 . 56 23 . 30 . 47 . 08 16 1. 16 13 Kyamte: _______________________ . 10 . 33 . 02 04 . 27 28 . 06 07 03 01 Tourmaline _____________________ . 12 . 04 . 04 13 . 33 16 ________ 03 . 03 03 1. Stream near Errada. 2. Beach near Gangavaram at Valametta. 3. Beach near Kutukonda. 4. Beach near Uppetem. 5. Beach 1 mile southwest of Vadamutupalem. . Beach 0.5 mile northeast ot Pudimadaka. . Stream near Kothuru. . Stream near Lemarti Agraharam. 9. Sand dune near Turkhodapalem. 10. Stream near Konavanipalem. wflm ASIA 73 250 feet, are locally steep, and are interrupted by rocky promontories which reach to the sea. Swamps and salt pans are present along parts of the beaches near Gangavaram and Valametta. Formation of black— sand streaks along the beaches depends on several factors including proximity of streams, gradient of the beach, wave activity, and currents. Most black sand is deposited where the largest number of small streams emerge from the hills and where the beaches are flattest and widest. In the area south of Visakhapat— nam, monazite constitutes only about 1 or 2 percent of the black sand, which is only about one-fourth of the tenor north of Visakhapatnam. Tonnage of monazite and other minerals in the black sand at Gangavaram and Pudimadaka was estimated by Anjaneyulu (1953, p. 97) to be as follows: Tana Monazite _________________________________ 1, 200 Zircon ____________________________________ 1, 250 Ilmenite __________________________________ 4, 200 Garnet ___________________________________ 5, 300 Magnetite ________________________________ 27, 000 Beaches north of Visakhapatnam have more ex- tensive black-sand deposits than those south of the town (Mahadevan and Rao, 1950, p. 48). Individual layers of black sand reach a maximum area of 500 by 100 feet and a maximum thickness of 8 inches. Be- cause of changes in the configuration of the beaches, there is a constant redistribution of the concentrates. Placers along the beach between Kailasa and Bhimi— lapatam are estimated to contain the following tonnage of the minerals given to a depth 5 feet below the surface (Mahadevan and Rao, 1950, p. 49): Tm Monazite _________________________________ 3, 100 Zircon ____________________________________ 550 Ilmenite __________________________________ 5, 700 Garnet ___________________________________ 12, 500 Magnetite ________________________________ 37, 000 Annually, during the monsoon months, a considerable amount of black sand is sorted, graded, and deposited on the beaches. Black sands are thought to extend to much greater depths than the 5 foot depth used for the estimate of the reserves, but maximum depths were not reported. The amount of thorium oxide in monazite from Madras and Andhra Pradesh was said (Wadia, 1956, p. 164; Canadian Mining Jour., 1955) to be between 5 and 11 percent. omssa Monazite was apparently first found on the coast of the Bay of Bengal in Orissa at Satbhaya (Satvaya) in the Cuttack district. In 1924 the deposits were exam- ined and found to extend for 23 miles along the coast (Mining J0ur., 1925a; 1947b; Petar, 1935, p. 16). The deposits have an average width of 70 feet and an average thickness of 10 inches. Black sand from the placers consists of 75 percent of ilmenite and a little garnet; the rest is monazite and other minerals. Richest concentrates have 11 percent of monazite; most concentrates have 2—3 percent of monazite. A monazite separate contained 7.9 percent of ThOz and 61 percent of RE203 (Mining J our., 1925a). A chemical analysis of nearly colorless to honey-colored monazite from a beach 1.5 miles east-northeast of Satbhaya was per- formed by the Chemical Research Laboratory at Teddington. Results indicated that the monazite con- tains 9.43 percent of ThO2 and 0.239 percent of U308 (Holmes, 1955, p. 90). JAPAN The monazite occurrence at Taijin-zan (Tanokami— yama) in Shiga-ken, initially described by J imbo (1899, p. 245), is the first of several monazite-bearing pegmatites and granites that have been reported in Japan. All the occurrences are of mineralogical inter- est only, and at least as late as 1956 no discovery of exploitable monazite had been made. Placers in areas having monazite—bearing pegmatite and granite, such as the regions near Ishikawa and Suisho-yama in Fukushima-ken and near Naegi in Gifu-ken, seem not to have been mined for monazite, although the history of placer mining for cassiterite in Gifu—ken extends back at least to the seventeenth century (Japan Ge-ol. Survey, 1956). Raised beach and stream placers have long been mined in Japan for iron. The iron sands are mixtures of ilmenite, titaniferous magnetite, and pyroxenes derived from mafic igneous rocks. Monazite was not reported by Staatz (1947, p. 3—8) even as a minor accessory mineral in the 138 iron sand deposits he described in Japan. The source of the monazite used to make the few tons of ferrocerium smelted in Japan and Korea dur- ing 1944—45 was from Korea (Bardill, 1946, p. 39—45) and Malaya (Fermor, 1950, table 2). Monazite is one of the few rare—earth-bearing miner- als found in Japan (Hoshina, 1926). The relation of the geographic distribution of rare-earth minerals to the regional geology was discussed by Kozu and Watanabe (1926, p. 839—841), and their interpretations, as related to the occurrence of monazite, are sum— marized before descriptions of specific localities are presented. The islands of Japan can be classed geologically into southwest and northeast halves, and each half can be divided into two zones. The halves are separated by a transverse lowland filled chiefly by sedimentary rocks of Tertiary age and covered by volcanic rocks. The 74 two zones of each half are called the outer zone on the Pacific side and the inner zone on the west side. In southwest half the outer zone consists mainly of strati- fied rocks of pre-Tertiary age, and the inner zone con- sists of extensive granodioritic rocks and only sparse sedimentary deposits. In northeast half the outer zone consists of four diagonal horsts geologically similar to the inner zone of southwest Japan. The inner zone of northeast Japan is made up mainly of sedimentary rocks of Tertiary age and younger volcanic rocks. As monazite in Japan is associated with pegmatite and granite, it most commonly occurs in the inner zone of southwest Japan and the outer zone of northeast Japan. Monazite has been found in the inner zone of southwest Japan in the following kens: Saga-ken and F ukuoka-ken on Kyushu and Yamaguchi-ken, Kyoto- ken, Nara-ken, and Shiga-ken on Honshfi. In the outer zone of northeast Japan, it has been found in Gifu—ken, Aichi-ken, Yamanashi-ken, Ibaraki-ken, and Fukushima-ken on Honshfi. INNER ZONE OF SOUTHWEST JAPAN Krfisnfi Pegmatite dikes at Nanzan-mura in Saga-ken con- tain monazite (Kimura and others, 1935, p. 100). Tabular dark—greenish-gray crystals of monazite as much as 1 inch across are found in a pegmatite dike at Amagi (Amaki, Ataka, Buzen, Kotoge) in Fukuoka- ken (Ito, 1937, p. 166). Monazite, having a specific gravity of 5.05, from the pegmatite was analyzed and was found to contain the following amount of thorium oxide and a remarkable amount of beryllium oxide: (Analysts: Kimura and Iimori (1936, p. 450; see also Kimura and Imlori, 1937, p. 1140, and Harada, 1948, p. 201)] Percent Percent 08203 _______________ 22 03 T102 ________________ 0. 00 Lagos (group) _______ } 38 57 ZrOz ________________ . 00 Y203 (group) ________ ' CaO ________________ .00 Th02 _______________ 5. 53 MgO _______________ . 00 U03 ________________ . 44 BeO ________________ 1. 44 P205 ________________ 26. 41 Loss on ignition ______ 1. 38 Si02 ________________ 3. 07 A1203 _______________ . 00 Total _________ 100. 39 Fe203 _______________ 1. 52 This analysis was reported by Kate (1958, p. 227) under the place name of Kotoge, Fukuoka-ken. The abundance of radium in the monazite from Amagi was reported by Kimura and Nakai (1937, p. 1258) to be Ra=0.0139><10‘7. HONsHiT Monazite—bearing pegmatite dikes containing ac- cessory zircon and xenotime are known at Y5 and Ishii in Yamaguchi—ken (Kimura and others, 1935, p. 100). Monazite is an accessory mineral in adamellite exposed on Hiei-zan in Kyoto-ken (Kozu and Watanabe, 1926, p. 842). THE GEOLOGIC OCCURRENCE OF MONAZITE Monazite from pegmatite at Hase-machi in Nara—ken, a locality also referred to as Kutinokura, Kaminago (Harada, 1948, p. 201), and Kuchinokura (Kato, 1958, p. 227) was reported to have the following composition: [Analystsz J. Masutoml and T. ngml (in Masutomi, 1944, p. 43)] Percent Percent 08203 _______________ 27. 77 F8203 _______________ 1. 33 Laan (group) ________ 28. 15 CaO ________________ . 47 Y303 (group) ________ 3. 01 MgO _______________ . 08 Th02 _______________ 6. 49 H20 ________________ . 64 P205 ________________ 29. 10 8102 ________________ 2. 64 Total _________ 100. 43 A1203 _______________ . 75 The first crystals to be recognized as monazite in Japan were reddish-brown inclusions in topaz identi- fied by Ogawa (Jimbo, 1899, p. 245; Ogawa, 1903). They came from a pegmatite dike at Taijin—zan (Tanokamiyama) in Shiga-ken (Kozu and Watanabe, 1926, p. 841—842; Iimori and Yoshimura, 1929, p. 30) OUTER ZONE OF NORTHEAST JAPAN House? The Ebisu wolframite and arsenic mine at Wada in Gifu-ken contains several monazite-bearing pneuma- tolytic quartz veins and accompanying greisen (Kato, 1958, p. 225). The sequence of rocks at the Ebisu mine includes sedimentary rocks of Paleozoic age which are intruded by quartz porphyry. These were intruded in Late Cretaceous time by porphyritic granite and biotite granite, which silicified the quartz porphyry. N umer— ous drusy pegmatites occur in the biotite granite. Cutting across the granite and the quartz porphyry are veins that carry wolframite, scheelite, bismuth miner- als, arsenopyrite, and monazite. The monazite, besides occuring in the quartz veins with the ore minerals, also occurs in topaz- and mica-bearing greisen and in the silicified wallrocks. It forms small disseminated yellow to dark—brown grains; crystal faces are rare. A sample of monazite from wolframite concentrates prepared at the mine, presumably from the quartz vein, was analyzed and was shown to have the following com- position: [Analyst Kata (1958, p. 226)] Percent Percent 06203 ________________ 24. 58 F8203 _______________ 0. 48 La203 (group) _________ 38. 51 CaO ________________ . 86 Th02 ________________ 4. 51 PbO ________________ . 026 U303 ________________ . 21 Loss on ignition ______ . 91 P205 _________________ 26. 81 8102 _________________ 2. 24 Total _________ 99. 49 A1203 ________________ . 36 Monazite is associated with thorite, fergusonite, and naegite in pegmatite dikes and cassiterite placers at Naegi in Gifu-ken. The area is underlain by grano- diorite, granite, and gneiss which are cut by many small pegmatite dikes and cassiterite veins (Kozu and ASIA 75 Watanabe, 1926, p. 841; Iimori and Yoshimura, 1929, p. 30). The dikes contain rare-earth minerals, garnet, tourmaline, topaz, sapphire, and andalusite. River beds and stream terraces are covered with cassiterite- bearing gravel in which are also found the thorium and rare-earth minerals and garnet plus magnetite, ilmen- ite, beryl, and chrysoberyl. Alluvial deposits at Naegi are strongly radioactive, and this radioactivity was attributed by Shibata and Kimura (1923a, p. 5) and Shibata (1926, p. 854) to monazite and thorite. A sample consisting of monazite and thorite was sepa- rated magnetically from a concentrate and chemically analyzed. Results of the analysis showed that this concentrate contained 8.52 percent of ThOZ. The mona- zite in this material probably did not contain more than 6 percent of Th02: [Analystsz Shibata and Kimura (19233, p. 5; see also Shibata, 1926, p. 854)] Percent Percent Genoa ________________ 19. 44 TiOz _________________ Trace Ndzos (group) ________ 19. 70 ZrOz _________________ Trace Dy203 (group) ________ 3. 54 Taz05 ________________ Trace Th0; ________________ 8. 52 Nb205 _______________ Trace P205 _________________ l20. 42 H20— _______________ 0. 69 SiOg _________________ 10. 81 H20+ _______________ 1. 64 l 20.24 on two. Monazite sand from Naegi was reported by Satoyasu Iimori (1929, p. 233) to contain 0.085 percent of U303 and 2.45 X 10'8 percent of Ra. Monazite was found in pegmatite dikes in Aichi-ken (Kimura and others, 1935, p. 100), and monazite occurs as inclusions in topaz in pegmatite at Kimpo- zan (Mt. Kimbu, Kinbuzan) in Yamanashi-ken (Kozu and Watanabe, 1926, p. 841; Iimori and Yoshimura, 1929, p. 30). It was also said by Iimori and Yoshi— mura to be present in pegmatite at Kuropira in Yamanashi-ken. This locality may be the same as Kurobei-yama, a mountain near Kimpo—zan. Peg- matite at Makabe in Ibaraki—ken contains monazite (Kimura and others, 1931, p. 212—213). The famous pegmatite district at Ishikawa in F ukushima—ken is a source for specimens of monazite, xenotime, samarskite, ishikawaite, zircon, columbite, and beryl (Kozu and Watanabe, 1926, p. 841; Iimori and Yoshimura, 1929, p. 30; Sato, 1926, p. 865; Saku- mi, 1941). Many pegmatite dikes intrude a virtually granodioritic terrane. Quartz, perthite, and mica occur as large crystals at some places in the dikes, and they are commonly accompanied by noteworthy crys- tals of tourmaline, garnet, and andalusite, as well as the rare minerals previously listed. Most of these minerals also occur as detrital grains in streams drain- ing the area. The monazite from Ishikawa was reported to form very perfect translucent brownish-yellow crystals. Selected crystals of monazite taken from a stream beside Ishikawa-yama were analyzed and found to have specific gravities of 5.17 and 5.195 and the follow- ing composition: [Analysts: A, Shibata and Kimura (1923b, p. 14—15; see also, Shlbata, 1926, p. 857); B, Ueda (1953, p. 228)] Percent A B 06203 __________________________________ 21. 08 (La, Nd)203 _____________________________ 31. 27 55. 41 Y203 (group) ____________________________ 3. 53 Th0; ___________________________________ 11. 08 11. 73 U03 ____________________________________ . 42 No data P205 ___________________________________ 27. 52 26. 69 Si02 ____________________________________ 2. 98 2. 73 A1203 ___________________________________ . 80 . 09 Fe203 ___________________________________ . 66 1. 49 CaO ___________________________________ . 52 1. 11 MgO ___________________________________ . 27 _________ H20 ____________________________________ . 56 1. 20 Total ____________________________ 100. 69 99. 45 1 0.05 H20+ and 0.15 H:0—. Variation in 0e203 content from 21.08 percent to 24.14 percent was noted by Shibata and Kimura in samples of monazite from Ishikawa. The samples were said to contain some Zr02, TlOz, and SnOz and to display considerable variation in Th02 and SiOz content (Shibata and Kimura, 1923b, p. 16): Percent Th0; __________________ 11.08 8.18 7.80 11.55 SiOz ___________________ 2. 98 1. 56 1. 82 3. 00 The following determinations of thorium, uranium, and radium in monazite from Ishikawa were made by Satoyasu Iimori (1929, p. 230, 232): Percent Th0; _________________________________ 9. 48 U303 _________________________________ . 70 Ra (mean of 3 samples) _______________ 20.21X10‘3 Monazite from Ishikawa contains 0.0027 percent of He (Sasald, 1926, p. 254). Where monazite is sparse in the pegmatites at Ishikawa, a little allanite is found, but Where monazite is common, allanite is very sparse (Kimura, 1925, p. 79). The abundance of thorium oxide in allanite from monazite-bearing and monazite-free pegmatites in Japan is about equal, but allanite from monazite-bearing pegmatites contains only about half as much of the rare earths as allanite from monazite-free pegmatites (Minami, 1929, p. 3). KOREA. The Korean Peninsula is underlain by Upper Cre- taceous batholiths of biotite granite, biotite—muscovite 76 THE GEOLOGIC OCCURRENCE OF MONAZITE granite, and porphyritic granite. Remnants of schist, gneiss, and sedimentary rocks form large roof pend- ants in the granite. Post-Cretaceous deposits of small areal extent fringe the peninsula. Monazite and xenotime are common minor accessory minerals in the Cretaceous granite and associated pegmatite dikes, in the gneiss and schist and in pegmatite related to the gneiss, and in the unconsolidated debris eroded from these rocks. Scarcely any stream in Korea that crosses the plutonic rocks lacks monazite, and beaches at the mouths of many streams on the east and west coasts are monazite bearing (Gallagher and others, 1946, p. 543—545). Sediments from the Korean coast of the Yellow Sea are more radioactive than sediments from other parts of the coast (Niino and Emery, 1961, p. 753). No primary monazite deposits of economic grade have been discovered in Korea. The commercial deposits are restricted to stream placers where mona- zite can be recovered alone or with gold and other minerals such as zircon, fergusonite, samarskite, euxenite, columbite, tantalite, and yttro—tantalite. Prior to 1942, no attention was paid to these minerals, although they are by no means scarce in some of the best gold-dredging ground in Korea. Between 1942 and 1945 some of the deposits were examined, and at a few placers a small amount of monazite was mined by hand methods. A monazite poll tax of 60 pounds of concentrate per year was said to have been imposed on the inhabitants of parts of Korea north of lat. 38° N. during the Russian occupation after World War II (Davidson, 1956a, p. 204). A revival of com- mercial interest in monazite during the late 1940’s and the 1950’s in the Republic of Korea led to an output reported to have exceeded a rate of 100 short tons a month in 1956 (Tong, 1956, p. 176), but this monthly rate was apparently maintained for only a short time because the production during 1956 was said to have been only 203 short tons (J. G. Parker, written com- mun., 1962). The following output was reported as concentrates containing 45—55 percent of RE203 and also reported as containing 30 percent of Ce which may be high. Short tom Short tons 1952 _________________ 903 1957 _________________ 392 1953 _________________ 845 1958 _________________ 355 1954 _________________ 1, 108 1959 _________________ 65 1955 _________________ 560 1960 _________________ 11 1956 _________________ 203 1961 _________________ 854 A published record (Parker, J. G., 1962, p. 1029) listed the output of monazite for Korea in 1961 as 28 short tons, but J. G. Parker (written c0mmun., 1962) subsequently stated that monazite production in 1961 reached 854 short tons. Korean resources in monazite seem to be capable of substantial development. The distribution of monazite deposits in the Re- public of Korea has been reviewed by Gallagher, Klepper, Overstreet, and Sample (1946, p. 546—576) and Tong (1956, p. 177), but the localities they de- scribe, which are summarized in the following discus- sion, are only a few of the many places where the mineral may be found. It is evident from the liter— ature that monazite is common throughout the country (Kim and others, 1958, p. 169—170; Lee and others, 1956, p. 49; Iimori, 1942, p. 410; Tsuda, 1941, p. 322— 325; Iimori and others, 1935a, p. 879). In the follow- ing review the deposits are described by province from south to north. CHGLLA-NAMDO Five monazite placers in Cholla—namdo were ex amined by the Korean Geological Survey and were estimated to contain about 70,000 short tons of mona- zite (table 20). The Songjéng—ni part of the Kwangju monazite placer area consists of streams north and west of the village in a part of Songjong-fip underlain by granite and gneiss intruded by rare porphyrite veins. In the Changp’yéng part of the Kwangju placer area, the streams drain granite and a little syenite exposed west of Changp’yéng and porphyrite dikes east of town. The easternmost headwater tributaries of the monazite-bearing streams in the Tamyang area drain quartz-mica schist and cholrite schist and the south- easternmost streams drain conglomerate of Mesozoic age (Son and Won, 1959, p. 116), but the main burden of the streams comes from granite. The Poséng-gun and Changhfing—gun placers occupy valleys of streams draining an area of granite gneiss, porphyrite, and syenite locally overlain by shale. High-grade occur- rences of monazite are in some valleys in the porphy- rite, syenite, or shale downstream from the gneiss. Streams draining only shale have no monazite placers (Kim and others, 1958, p. 169—170, figs. 4—7 ). Heavy minerals from weathered samples of granite and gran- ite gneiss in the Tamyang area show that these rocks contain from 0.0001 to 0.009 percent of monazite (Son and Won, 1959, p. 116). Kurye-gun gold placers are monazite bearing (Tong, 1956, p. 177). CH6LLA-PUKTO The Province of Chélla-pukto includes monazite placers in the Kumje-gun alluvial gold zone and de- posits in Iksan-gun and Muju-gun (Tong, 1956, p. 177 ; Gallagher and others, 1946, p. 546—576; Iimori and others, 1935a, p. 879). The Kumje-gun alluvial ASIA 77 TABLE 20.——Size and tenor of selected monazite placers in CMlla—namdo, Ch’ungch’dn’g-pukto, and Kyénggi-do, Korea [Modified from Kim, Hwang, and Sang (1958, p. 169-170)] Tenor Area Depth Volume Resources of Placer (thousands (feet) (thousands Percent monazite of sq yds) of cu yds) Pounds per (short tons) cubic yard Raw sand Concentrate Chollarnamdo: Songjbng-ni ______________________________ 3, 389 15. 7 23, 000 0. 049 21. 1 1. 6 17, 800 10, 570 5. 2 18, 500 . 127 43. 8 3. 6 33, 500 Changp’yeng _____________________________ 2, 440 7. 2 5, 800 . 061 34. 5 1. 7 5, 100 120 6. 9 270 . 055 44. 0 1. 6 220 240 8. 8 700 . 079 42. 0 2. 4 860 Tamyang ________________________________ 5, 500 8. 5 15, 600 . 051 15. 3 1. 6 12, 200 120 6. 6 260 . 068 19. 6 2. 1 280 Posbng-gun ______________________________ 380 8. 2 1, 000 . 038 24. 0 1. 2 600 104 5. 2 180 . 081 28. O 2. 1 190 Changhfing-gun __________________________ 12 1. 6 6 . 057 33. 5 1. 7 5 9 3. 3 10 . 051 34. 0 1. 6 8 Ch’ungch’bng—pukto: Munbaek-mybn, Chinch’on-gun ____________ 860 6. 6 1, 880 . 045 15. 0 1. 2 1, 100 14 3. 6 17 . 047 35. 0 1. 4 12 39 3. 9 50 . 039 27. 0 1. 2 30 14 3. 9 20 . 053 25. 4 1. 6 15 1 4. 3 2 . 072 15. 0 2. 2 2 4 2. 9 5 . 037 13. 0 1. 2 3 Kyonggi-do: Chbnghowon—fip __________________________ 3, 600 9. 8 11, 800 . 052 16. 9 1. 6 9, 200 1, 970 13. 8 9, 000 . 046 15. 1 1. 3 5, 900 __________ 7.5 __________ .026 22.5 .8 __________ 1, 540 3. 9 2, 000 . 120 18. 8 3. 6 3, 600 __________ 7.5 __-__-_-__ .011 5.6 .3 _-_____-__ gold zone consists of placers in Kfimsan-myon of which the best known is the Kumje Ch’aegum near Songke—ri where gold is accompanied by monazite, zircon, samarskite, columbite, and fergunsonite. A concentrate consisting of 90 percent of monazite from the Pongsa-ri area of Hari-myén in Kfimje-gun con- tained 6.7 percent of Th02 (Iimori, Satoyasu, 1942, p. 410). Recalculated to 100 percent, the monazite would contain 7.3 percent of ThO‘z. Two-mica granite in the vicinity of Chong—fip has from 0.0001 to 0.0287 percent of monazite as an acces- sory mineral. Its average abundance is 0.0018 percent (Son and Won, 1959, p. 116). An eluvial placer in Kumma-myén (Kumna-myon) and Wanggung-myon, Iksan-gun, has 2—15 percent of monazite mixed with magnetite, martite, ilmenite, and zircon. In Choksang-myon, Muju-gun, monazite is in co- lumbite—bearing pegmatites and associated placers. CH’UNGCH'ONG-NAMDO Ch’ungch’ong-narndo includes the Ch’onan alluvial zone mentioned by Tong (1956, p. 177) where monazite is associated with columbite, tantalite, fergusonite, samarskite, xenotime, zircon, wolframite, rutile, ilmen- ite, spine], magnetite, sillimanite, corundum, garnet, and gold. Gold placers in Ch’onan-gun are among the largest in Korea and of these the Songhwan placer in Ipchang-myon (Iimori and others, 1935a, p. 879) and the Chiksan placer (Iimori and Yoshimura, 1929, p. 30) in Chiksan-myon probably are the best sources of monazite. Other monazite deposits in Ch’onan—gun include the Sungnam fergusonite and gold placer, gold placers in Ipchang-myén along the Ipchang-ch’on to its junction with the Ansong-ch’én, the Sinhung placer in Paebang—myon, the Sanjijang placer in Susin-myon, and prospects for monazite, zircon, ilmenite, and gar- net in Tong-myén. The placers are formed in broad valleys on granite and granite gneiss locally intruded by porphyry. The monazite often occurs in elongate, subhedral or broken euhedral grains (Hwang and Park, 1956, p. 116, 121—122). Several analyses are available for monazite from the Ch’onan placer district. A complete analysis on ma- terial from Chiksan placer shows the following amount of Th0,, but seems to be of an impure concentrate because it contains rather large amounts of SiOz, (Nb, Ta)205, and Zr02: [Analystz Shibata. (1926, p. 864)] Percent Percent 08203 _______________ 24. 69 T102 ________________ 0. 19 Nd203 (group) _______ 31. 16 Z10; ________________ 1. 05 Y203 (group) ________ 2. 31 (Nb, Ta)205 _________ 1. 50 Th02 _______________ 5. 47 03.0 ________________ . 53 P205 ________________ 25. 89 Loss on ignition ______ . 68 $102 ________________ 4. 08 A1203 _______________ 1. 36 Total _________ 100. 26 Fe203 _______________ 1. 35 78 THE GEOLOGIC OCCURRENCE or MONAZITE Various samples of monazite from Chiksan placer were reported by Satoyasu Iimori (1929, p. 230, 233) to contain 6.91, 6.46, and 6.33 percent of Th02, 0.582 percent of U308, and 16.80><10‘8 percent of Ra. Sasaki (1926, p. 254) found that monazite from Chiksan placer had 0.0017 percent of He. Monazite from placers in Ipchang-myén, Ch’onan- gun, was said by Satoyasu Iimori (1942, p. 410) to contain 6.9 percent of ThOZ and by Hwang and Park (1956, p. 116) to contain 7.08 percent of Th0;, 60.14 percent of the RE203 and 0.50 percent of U303. Mon- azite from the Sungnam fergusonite and gold placer contains an average of 5.3 and ranges from 5.1 to 5.5 percent of Th02 and contains 0.71 percent of U308 (Yoon and others, 1956, p. 74). Placer operations in 1944 along the valley of the Kfim-gang and its tributaries in Puyé-myén, Puy5—gun, and adjacent areas of N onsan-gun were reported (Gallagher and others, 1946, p. 558) to have recovered 2,200 short tons of concentrate consisting of monazite and zircon. The Choson placer in Ungch’on-myén, Porycng-gun, produced 17.5 short tons of zircon and monazite in 1944. Other deposits are known at Taech’on-mybn and Ch’éngna-myon in the same general area. Monazite of unknown source in Hongbuk-myon, Hongsong-gun, was reported to contain 4.8 percent of Th02 (Iimori, Satoyasu, 1942, p. 410). A beach placer in Soch’on-gun extending from S0— myén eastward along the Yellow Sea into Piin-mybn was the source of 57 short tons of monazite concentrate in 1944. The alluvium in the Haki-ri placer in T’andong- myén, Taedék-gun, has from 0.8 to 1.0 percent of heavy minerals in quartz sand and gravel. The coarsest fragments in the gravel are about 3 inches in diameter. In the raw sand the heavy minerals average about 0.14 percent of monazite, 0.39 percent of magnetite and ilmenite, 0.12 percent of garnet, and 0.1 percent of zircon. Inasmuch as only 4.5 percent of the monazite is as large as —45 mesh and 50 percent of the raw sand coarser than —35 mesh, at least half of the raw sand can be removed with little loss in monazite. In 1957 the deposit was being worked by simple hand methods (Roe and An, 1958, p. 36). The Chénfii placer in valleys north of ‘Chénfii in Chénui-myén, Yon-gi-gun (Yongi—gun), was mined in a small way in 1946 for fergusonite. Monazite and gold were among the heavy minerals recovered. Placers along the Miho—ch’én, Chak-ch’én, and Cho- ch’6n in the vicinity of Choch’iwén in Yongi-gun produced 11 short tons of monazite concentrate in 1944. The concentrate included zircon and possibly some scheelite. CH’UNGCH’ONG-PUKTO Monazite in Ch’ungch’éng—pukto is concentrated with zircon, magnetite, titanite, pyroxene, and horn- blende in the sediment of the Changp’yéng-ch’én in Pongyang-myén, Chech’én-gun and in the Ch’ongwon- gun placer mineral zone in Oksan-myén, Och’ang- myén, and Puyong-myén Where it is associated with zircon (Tong, 1956, p. 177; Gallagher and others, 1946, p. 556). It has been found in Koesan-gun. The Munbaek-myén placer in Chinch’én-gun is formed in small streams draining granite gneiss and was re- ported (table 20) to have a reserve of about 1,200 short tons of monazite (Kim and others, 1958, p. 169- 170). KYONGSANG-NAMDO AND KYONGSANG-PUKTO A concentrate containing 80 percent of monazite from Hadong-up, Hadong-gun, Kyéngsang—namdo, was said to contain 3.7 percent of Th02 (Iimori, Satoyasu, 1942, p. 410). If calculated to pure mona- zite, the tenor in Th02 becomes 4.6 percent. The geologic occurrence is unknown. In Kyéngsang-pukto 19 alluvial placers having 2— 14 percent of monazite in the heavy minerals are known in a region including parts of Yonggung—myon, Kaep’o-myén, Kamch’én-myén, Yech’én-fip, Yong- mun-myén, Yuch’én-myén, and Sanbuk-myén in Yech’ 6n-gun and Mun’gyong-gun. At the P’unggi placer in P’unggi-myén, Yongju-gun, 1,598 short tons of con— centrate Containing 4—5 percent of monazite was re- covered between 1942 and August 1945 by panning garnet-rich layers in alluvial sand. These layers make up less than 1 percent of the sediments in a flood plain that is 10 miles long and 0.5 mile wide. KANGWON-Do Monazite-bearing beach placers extend intermittently northward from Chumunjin, Kangnfing—gun, to Késong- gun along the shore of the Japan Sea to form the Koséng coastal placer area (Tong, 1956, p. 177; Yoon and others, 1958, p. 189). Originally the deposits were known as ilmenite placers, but investigations in 1956—58 disclosed detrital monazite and zircon. Sand from Hwajin-p’o in the K5s5ng placer district contains about 10 percent of heavy minerals consisting of 3.5 percent of ilmenite, 0.2 percent of monazite, 0.2 percent of magnetite, 0.6 percent of zircon, 3.2 percent of garnet, and 2.7 percent of epidote (Roe and others, 1958, p. 38). The area where the placers have formed consists mainly of mica schist and injection gneiss of Precam- brian age intruded by granite of Cretaceous age. ASIA Placers occur on the beaches, in river-mouth bars, and bay—mouth bars. Particularly well-defined deposits have been found north of Oho-ri and around Konghyénji- ri in Chukwang-myén, Yangyang-gun. They also occur between Kajin-ni and Panam-ni in Kansong-myon, at Kojin-ni in Kojim-myon, between Changpyong-ni and Chodo-ri, from Chedo-ri to Chaltong-ni, and along the shore south of Musongjong in Hyonnae-myon, Késong- gun. Concentrates from the placer district were re— ported to contain 4.24 percent of Th02 in mixtures having unreported abundances of monazite (Yoon and others, 1958, p. 200). The monazite was said to have 6.9 percent of ThO2 (Iimori, Satoyasu, 1942, p. 410). At least 1,600 short tons of monazite were estimated to be in the placers in the district (Yoon and others, 1958, p. 206). Monazite and zircon occur in stream placers in Hyonnam-myon, Yangyang-gun. KY6 NG GI-DO AND HWANGHAE—DO Near Seoul in the province of Kybnggi-do, monazite occurs With zircon in placers in Sé-fin-myen of Ansong— gun. Monazite is associated with zircon, spine], garnet, and magnetite in residual and alluvial deposits near the confluence of the Pokha-ch’on and Han-ch’on in Paeksa—myon, Sindun-myon, and Ich’on-up of Ich’on- gun. A large placer south of Chénghowon in Chongho- won-up, Ich’bn-gun, is in a valley which in part con- tinues northward along the contact between granite on the west and granite gneiss and mica schist on the east (Kim and others, 1958, fig. 9). The placer contains 18,700 short tons of monazite. Monazite from a deposit in Chinbong-myén, Kaesong— gun, contains 5.5 percent of Th02 (Iimori, Satoyasu, 1942, p. 410). The Kwangu Paeknyon gold placer along the Sutnae- ch’on in Chungdae-myon and Kuch’bn-mybn, Kwangju- gun, contains monazite and zircon. Traces of monazite and zircon are in concentrates at the site of former gold dredging in Wonsam-myon, Yong-in-gun. An alluvial placer extends about a mile down the Ansong-ch’on in Songt’an-myon, P’yongt’aek-gun, from the town of P’yéngt’aek to tidewater. In 1944 the placer produced 45 short tons of sand which contained 70 percent monazite and zircon. Off the coast of Kyonggi—do, monazite occurs on the islands of Yongyu—do in Yonghéng-myon, Puch’on—gun, and Kanghwa-do in Scnwon—myon, Kanghwa—gun. The deposit on Kanghwa-do, known’as the II Pung gold placer, yields black sand composed dominantly of ilmenite and columbite or tantalite, corundum, 30 percent of monazite, and less than 1 percent of red garnet and zircon. North of Seoul in the province of Hwanghae-do, the Kukum gold placer in Haewol—mybn, Yonbaek-gun, 79 may be the finest fergusonite deposit in Korea (Gal— lagher and others, 1946, p. 575). Concentrates from the placer have the following composition: Percent Monazite __________________________________ > 12 Zircon _____________________________________ 10 :1: Garnet ____________________________________ < 5 Scheelite ___________________________________ 1 4. 8 Ilmenite and rutile __________________________ 60:1: Magnetite _________________________________ < 2 Fergusonite ________________________________ 2 7—27 Columbite _________________________________ 5—12 1 >14-in. mesh. 2 >28-in. mesh. Monazite from Haewbl—mybn, probably from the Kukum placer, was reported to have 11.0 percent of Th02, a composition which makes it the most thorium oxide-rich monazite in Korea (Iimori, Satoyasu, 1942, p. 410). P'YONGAN-NAMDO AND P'YONGAN-PAKTO Monazite was recognized as early as 1919 as one of the minerals in the Sun-an gold placer in Tongam- myon, Pyongwon—gun (Koto, 1919). A complete analysis of monazite from the Sun-an placer follows: [Analysts2 Kimura and Shinoda (1931, p. 50)] Percent Percent Ce203 ________________ 28. 25 SnOz _________________ 0. 15 Nd203 _______________ 27. 87 09.0 _________________ , 53 Yan ................. 2. 47 PbO _________________ , 09 T1102 ———————————————— 9- 49 Sb205 ________________ _ 06 3‘3; ----------------- 26- (1)3 002 ................. .23 sio: _________________ 1. 85 H20+ """"""""" ' 79 A1203 ________________ . 28 _'_’_ F6203 ________________ 1. 65 Total __________ 99. 93 Partial analyses of monazite from Sun-an have also been published: 9. 56 . 111 3. 21X10—a Helium ______ 1 Specific gravity, 5.11. References: 1. Sasaki (1926, p.254). 2. Satoyasu Iimori (1929, p. 230). 3. Satoyasu Iimori (1929, p. 233). 4. Tsuda (1941, p. 325). 5. Satoyasu Iimori (1942, p. 410). The age of this detrital monazite was determined by Satoyasu Iimori (Tsuda, 1941, p. 325) to be 117 million years, which indicates that it was probably derived from the Cretaceous granite or related peg- matite. The Sun-an placer is part of the Pyongwon—gun placer monazite zone of Tong (1956, p. 177). Sunch’én-gun is the center of reported occurrences of monazite in placers and pegmatites: Pongch’ang-ni 80 in Pongton-myén, Kusang—ni and Chungsang-ni in Pukch’ang-myon, Taepyéng-ni in Unsan-myon, and Happ’i-ri in Wént’an-myén (Iimori and others, 1935a, p. 879; Lee and others, 1956, p. 49). Analyses of monazite from Pongton-myén and Unsan-myon show 7.1 and 5.5 percent of T1102 (Iimori, Satoyasu, 1942, p. 410). Concentrates from placers in the Pongch’ang—ni area of Pongtong-myén and the Taepyéng-ni area of Unsan-myén were reported to contain from 7 to 12 percent of monazite (Iimori and others, 1935b, p. 354) : Percent Pongch’ang-ni Taepyéng-ni lVIonazite ______________ 8 3 12. 4 7. 0 10. 4 lmenite _______________ 30. 5 19. 0 Other minerals __________ 61. 2 87' 6 { 74. 0 89‘ 6 Monazite has been found at Chajak-ri in Puk-myén and in Pongtong-myén, Kaech’on—gun (Iimori and others, 1935a, p. 879; Lee and others, 1956, p. 49). It has also been reported from Sin-ni in Yongwén-myon, Yongwén-gun, P’yongan-namdo. Three analyses of monazite from other localities in P’yongan—namdo show 5.1, 6.0, and 6.2 percent of ThO2 (Iimori, Satoyasu, 1942, p. 410). Monazite was said to occur in gold placers at Kan- dong, Sinsu-myon, Sonch’on-gun. It has been found in large lumps in Cholsan-gun (Tong, 1956, p. 177). Several other localities in P’yongan-pukto were re- ported to be monazite bearing (Iimori and others, 1935a, p. 879; Lee and others, 1956, p. 49). HAMGYéNG-NAMDO AND HAMGYONG-PUKTO Black monazite occurs in heavy concentrates ob- tained from sand and gravel on bedrock at a depth of 20 feet below the paddies at Inhfing-myén, Yonghfing-gun, Hamgyong-namdo. The following is a complete analysis of this black monazite which had a specific gravity of 5.16: [Analyst Takeo Ilmori (1941, p. 1052)] Percent Percent 06203 _______________ 25.10 A1203 _______________ 0. 45 (La, Nd)203 (group) __ 37. 14 Fe203 _______________ . 42 Y203 (group) ________ 1. 26 CaO ________________ 1. 58 ThOZ _______________ 5. 81 MgO _______________ . 00 U03 ________________ . 66 BeO ________________ . 00 P205 ________________ 27. 55 Si02 ________________ . 93 Total _________ 100. 90 Monazite from the same locality has also been re— ported to contain 6.6 percent of Th02 (Iimori, Satoyasu, 1942, p. 410). THE GEOLOGIC OCCURRENCE OF MONAZITE Monazite was reported to occur with rutile in placers in the province of Hamgyong-pukto at Sangjin-dong, KWanhae-myon, Puryong-gun (Lee and others, 1956, p. 49). PAKISTAN A concentrate from the Indus River at Amb, Hazara District, West Pakistan, contains abundant magnetite and lesser quantities of ilmenite, zircon, monazite, garnet, uraninite, uranothorite, amphibole, and scheelite (Danilchik and Tahirkheli, 1959, p. 5). Spectrographic analysis of a concentrate from cobble gravel in the Hunza River at a point 0.5 mile above its confluence with the Gilgit River showed thorium and the rare earths in abundances interpreted by Danilchik and Tahirkheli to indicate monazite in the alluvium. At both localities the main source of the detrital minerals is granodiorite and metamorphosed mafic volcanic rocks. As late as 1959 no economic deposits of placer monazite had been found in West Pakistan. Beach placers containing monazite were reported from 10 localities along the east coast of the Bay of Bengal, East Pakistan, extending from Chittagong to the Burmese border (Schmidt and Asad, 1962). The placers, generally containing 10—30 percent heavy minerals, are on the ocean beach and in the foredunes. Each placer is tens or hundreds of feet wide and several hundreds to thousands of feet long; one extends for several miles. Local lenses that contain as much as 96 percent minerals of specific gravity exceeding 2.80 were found at several localities within the placers. A recon— naissance study of one of these placers indicated pro- visional reserves of 487,000 short tons of sand containing 10 percent heavy minerals, 163,000 short tons of sand containing 20 percent heavy minerals, and 6,300 short tons of sand containing 30 percent heavy minerals (Schmidt and Asad, 1963). Monazite percentages were not estimated, and no attempt has been made to exploit these placers. Magnetite makes up 8 percent of the heavy minerals in the main placers, which contain 10—30 percent heavy minerals, but about 50 percent of the heavy minerals in the lenses that consist almost entirely of heavy minerals. The main placer at Cox’s Bazar contains the following heavy-mineral suite: Abundant Common Sparse Magnetite Tourmaline Amphibole Pyroxene Staurolite Kyanite Ilmenite (?) Zircon Mus covite Epidote Rutile Biotite Garnet Monazite The monazite in the Cox’s Bazar placer is pale yellow, yellowish gray, brownish yellow, and whitish yellow in samples examined by the author. ASIA 81 PHILIPPINES Seventeen samples of sand from streams and beaches in the Philippines were determined by Bacon (1910, p. 277—27 8) to be radioactive. Very radioactive black sand from Nueva Ecija contained magnetite, zircon, gold, platinum, monazite, and probably iridium. Black sand near Paracale, Ambos Camarines, Luzon, contained very radioactive monazite. The localities of the 15 other radioactive samples of sand were not given. REPUBLIC OF INDONESIA Monazite is found in the alluvial tin placers on the islands of Belitung, Bangka, and Singkep between Sumatra and Borneo (Gisolf, 1926, p. 1729). It prob— ably occurs with cassiterite in placers on the Kepu— laun Riau elf the tip of Malaya along the trend of the monazite-bearing tin and tungsten placers that have been mined as far north as Burma (Bemmelen, 1949, p. 92, 95). Monazite is in stream placers near Bengara, Kalimantan (West Borneo), and has been found on the beaches of Kalimantan and northern and western Sumatra. On the three main “tin islands” of Belitung (Billiton Island), Pulau Bangka (Banka Island), and Pulau Singkep (Singkep Island), monazite is associated with cassiterite. A placer on Pulau Bangka was said to have contained too much monazite to permit profitable recovery of the cassiterite (Davidson, 1956a, p. 203— 204), but there is no record that the monazite was shipped from the island. Five tons of monazite was mined at Belitung in 1896, and an unrecorded amount was produced in 1909 (Davidson, 1956a, p. 203). Small but unreported amounts of monazite were shipped from Pulau Singkep in 1894, 1895, and 1896. Most of the recorded production of Indonesia has been from the tin placers on Pulau Singkep. Between 1936 and 1939 the output of monazite was 1,713 short tons (Neder- landsch—Indié, Dienst van den Mijnbouw, 1938; Eco— nomic Weekblad voor Nederlandsch-Indié, 1940, p. 739; Bemmelen, 1941, p. 16; 1949, p. 146; Staufi'er, 1945, p. 332): Short tons 1936 ______________________________________ 736 1937 ______________________________________ 408 1938 ______________________________________ 433 1939 ______________________________________ 136 Total _______________________________ 1, 713 Varying amounts of monazite were produced in the 1950’s and early 1960’s (Crawford, 1957a, p. 6; J. G. Parker, written commun., 1962): Short tom 1953 ______________________________________ 314 1954 ______________________________________ 11 1955 ______________________________________ 122 1956 _______________________________ Not available 1957 _______________________________ Not available 1958 _______________________________ Not available 1960 _______________________________ Not available 1961 ______________________________________ 111 The position of Pulau Singkep as the leading producer of monazite in Indonesia may be due to the greater amount of thorium oxide in monazite from that island in contrast to thorium oxide-free and hence commer— cially unacceptable monazite from Belitung. Placer monazite from Pulau Singkep was reported to contain 3.27 and 3.4 percent of ThO2 (Davidson, 1956a, p. 204). Two analyses of detrital monazite from a tin placer near Dendang on Belitung follow: [Analystz C. Winkler (in Hintze, 1922, p. 342, 370)] Percent . A B 0e203 __________________________________ 56. 79 60. 54 (La, Nd, Pr)203 __________________________ 8. 60 6. 86 Y203 ___________________________________ 2. 29 1. 08 T1102 ___________________________________ . 00 . 00 P205 ___________________________________ 29. 76 29. 37 SiOz ____________________________________ . 91 1. 44 Fe203 ___________________________________ . 22 Trace NiO ____________________________________ . 50 _______ SnOz ___________________________________ Trace _______ Loss on ignition _________________________ . 59 . 39 Total _____________________________ 99. 66 99. 68 A. Specific gravity 4.92. B. Specific gravity: 4.94. These analyses showed no thorium oxide, and in this respect the monazite resembles thorium-free monazite from tin veins at Cerro de Llallagua, Bolivia (Gordon, 1944, p. 330). The bedrock source of the monazite in the Dendang placer is not known. The monazite may have come from cassiterite-bearing granite east of Dendang, or from greisen and cassiterite—bearing quartz veins in the granite, or from contact zones and cassiterite- bearing quartz veins in the feebly metamorphosed sandstone into which the granite is intruded (Bemmelen, 1949, p. 96, 99—101). The sandstone is not likely to have been the source. Minerals associated with detrital monazite in the cassiterite placers on Belitung, Pulau Bangka, and Pulau Singkep are xenotime, ilmenite, pyrite, mar- casite, hematite, rutile, allanite, zircon, and tourmaline. The cassiterite granites of Pulau Bangka contain allanite, zircon, and apatite, but monazite has not been observed in them, although it is in concentrates from the placers. Monazite was found in granite, biotite gneiss, and biotite schist on Pulau Berhala in 82 the Strait of Malacca (VVesterveld, 1936, p. 1123— 1124). Monazite was found along the north and west coasts of Sumatra, but the exact localities were not reported (Van Wickel and George, 1924, p. 544; Chem. Trade Jour. and Chem. Engineer, 1924; Chem- ische Industrie, 1924). Several reports in 1924 announced the discovery of monazite in Kalimantan (West Borneo), and one stated that monazite seemed to be present in large quantities, but evidently the reports were somewhat exaggerated (Chem. Trade J our. and Chem. Engineer, 1924; Metallurgie und Erz, 1924; Chemische Indus- trie, 1924; Van Wickel and George, 1924, p. 544). Levy introduced a note of confusion into the reports by incorrectly reporting that this monazite contained 9 percent of T1102 (Levy, 1924a). Very fine samples of perfectly crystallized monazite were found in Kalimantan near the border with Sara— wak (Gisolf, 1926, p. 1729). Monazite occurs in gneissic quartz diorite in the migmatitic area in the southeastern part of the Kem- bajang Mountains of central and eastern Kalimantan (Zeijlmans van Emmichoven, 1939a, p. 50—53, pl. 1; 1939b, p. 194; Roe, 1958, p. 47). Gneissic granite exposed in the Halilit River in central Kalimantan is intruded by veins of granite pegmatite which contain tourmaline, cassiterite, and monazite (Nederlandsch-Indie', Dienst van den Mjin- bouw, 1935, p. 22) . Five samples of sandstone of Triassic age from northeastern Timor contain a fraction of a percent of monazite (table 21). TABLE 21.—Mr'neralogical composition, in percent, of heavy- mineral fraction, of monazite-bearing concentrates from sand- stone of Triassic age in northeastern Timor [Modified from analyses by Simona (1939, p. 74-76)] 1 2 3 4 5 Opaque minerals _________ 67. 5 57. 0 85. O 77. 0 14. 5 Tourmaline ______________ 4. 2 7. 5 l. 8 3. 0 5. 5 Zircon ____________ 13. 0 18. 3 3. 8 9. 9 3. 8 Garnet____ _-_ 8. 1 10. 8 5. 1 5. 0 65. 7 Rutile _____ _ _ 3. 2 1. 5 .9 1. 6 2. 5 Brookite ____________________________________ . 4 Anatase _________________ . 7 ______ . 2 2 . 8 Titanite _______________________ . 4 . 2 ______ . 8 Milscovite _______________ 1. 3 1. 5 1. 8 1. 2 1. 2 Epidote _________________ . 3 . 4 . 2 . 2 1. 6 Hornblende (blue-green)--- . 7 ______ . 6 l. 2 ______ Chromite ________________ . 3 1. 1 . 2 . 2 l. 6 Monazite ________________ 7 1. 5 . 2 . 5 1. 6 1. (‘vraywacke sandstone exposed in the Motta Baoekonoe south of Babkaniem, 2. Graywacke sandstone exposed in the Motta Baoekonoe south-southwest of Weklosoen. 3. Sandstone with calcareous cement exposed near the highest point on the path between Tabean and Woonarl. 4. Sandstone with calcareous cement exposed southwest of Weklosoen. 5. Grlayvgacke from the valley of Motta Toebatan about a mile downstream from 0e atan. THE GEOLOGIC OCCURRENCE OF MONAZITE SARAWAK AND NORTH BORNEO SARAWAK The earliest description in the literature of a natural concentration of monazite sand was made by Hugh Low when he commented upon but did not identify monazite at Lingga (Lingah), Sarawak. Low (1848, p. 29) wrote: A beautifully resplendent sand, the particles of which resemble amethysts and topazes, and which is used in the adulteration of gold dust, may perhaps be thought to indicate the vicinity of other gems: it is found at Lingah, a branch of the great Batang Lupar river, not far from its mouth. Over a hundred years later Haile (1954, p. 103) identified the occurrence as monazite in a stream sand near Gunong Lesong. Gunong Lesong is a spectacu- lar flat—topped mountain composed of microgranite of pre-Tertiary age which is capped by a nearly hori- zontal layer 500—1,000 feet thick, of sandstone of Ter- tiary age. Sand from streams on the north and north- east flanks of Gunong Lesong contains small euhedral crystals of monazite, often in considerable abundance, associated with tourmaline, andalusite, zircon, and topaz. The source of the monazite was inferred to be the microgranite, though monazite was not certainly identified in the rock (Haile, 1954, p. 35, 102; Wil- ford, 1953, p. 33; Haile, 1952, p. 14). A monazite separate from the Gunong Lesong area, prepared by S. H. U. Bowie of the Atomic Energy Division, Geological Survey of Great Britain, con- tained 6.8 percent eThOz (Haile, 1954, p. 102). Monazite was found by N. S. Haile in 1955 in con- centrates from the Sungei Entabai (Entabai), a trib- utary to the Batang Rajang, and in 1957 was discov- ered by E. B. Wolfenden in sand near Sibu in the Batang Rajang delta (Roe, 1958, p. 20—21). Although the primary source of the monazite in these localities is unknown, the source is probably granitic and meta- morphic rocks in the western part of Sarawak and adjacent parts of Kalimantan. The immediate source of the monazite in the Sungei Entabai is sedimentary rocks. They are probably in part the immediate source for some of the monazite in the delta of the Batang Raj ang, but some of the monazite in the delta- has probably come directly from the crystalline rocks of the hinterland. Black marine sand rich in ilmenite and zircon was discovered near the mouth of the Batang Bintulu in 1950 by N. S. Haile (Wilford, 1953, p. 33; Kirk, 1957, p. 57—68; Kirk, 1958, p. 85). Small quantities of monazite, rutile, and garnet are present, and these heavy minerals are accompanied by magnetite, corun- dum, sillimanite, andalusite, chiastolite, staurolite, AUSTRALIA, NEW ,ZEALAND, AND ANTARCTICA 83 tourmaline, brookite, anatase, sphene, and apatite. The sand is banded and the main concentrations are near the high tide mark and extend 2% miles along the arcuate coast from Tanjong Batu to Tanjong Kirudong. Backing the beach is a wide coastal plain consisting of Recent alluvial sediments and older alluvial and marine deposits overlying sandstone of Miocene age. Four main types of coastal deposits are present (Kirk, 1957, p. 57—59): (1) modern beach sand, (2) beach sands forming a platform at the back of the present beach and about 7 feet above sea level, (3) raised beach and alluvial deposits which fringe the hills at an altitude of 30 feet above sea level, and (4) Recent alluvial deposits. Recent alluvium is bar- ren of heavy minerals. No concentrations of heavy minerals have been found in the raised beach and alluvial deposits at the 30-foot level, and only a little black sand occurs in the 7 -foot platform. The main deposits of banded black sand are in the modern beaches. Only 30,000 tons of sand estimated to con- tain an average of not less than 5 percent of ilmenite and zircon are in the deposit. Mineralogical analyses disclosed that monazite makes up less than 1 percent of the concentrate. The deposit was regarded as un— economic in 1957 (Kirk, 1957, p. 57). The source of the heavy minerals in the deposits between Tanjong Batu and Tanjong Kirundong was thought by Kirk (1957, p. 67) to be crystalline rocks in western Sarawak and parts of Indonesian Borneo. During maximum glaciation the lowering of sea level may have caused regression of the sea from the Sunda Shelf, and rivers whose headwaters were in the crys— talline rocks of western Borneo may have deposited their alluvium in the present China Sea adjacent to the Batang Bintulu area. Reworking of these de— posits, and longshore drift, may have formed the present deposits (Kirk, 1957, p. 67~68). That large black sand deposits are present is im- probable. At none of the four areas in Sarawak where monazite is known is it sufficiently abundant to be recovered (Roe, 1959, p. 40). NORTH BORNEO Deposits of monazite are known in three places in North Borneo, but they are uneconomic owing to their small size and inaccessibility (Collenette, 1956, p. 172; Fitch, 1956, p. 179; Roe, 1957, p. 130). The deposits are at the extreme head of the Sungei Segama (Segama River), somewhat farther downstream on the Sungei Segama Where they are associated with placer gold and black sand, and near the mouth of the Sungei Tingkayu (Tingkayu River), which empties into Darvel Bay. The upper parts of Sungei Segama drain intermediate and mafic igneous rocks, and the basin of the Sungei Tingkayu is underlain mainly by sedimentary rocks of Tertiary and Quaternary age (Roe, 1958, p. 128). TEAILAN D Monazite occurs in pegmatite veins and granite gneiss, and in eluvial deposits accumulated therefrom, in western Thailand, but it has yet to be discovered along the beaches in southern Thailand. Its best known occurrence is with cassiterite, tantalite, colum- bite, ilmenite, and garnet in alluvial tin placers near the west border of the country and in the peninsula between Burma and Malaya. These placers are a northern extension of similar deposits in Malaya. Tailings from cassiterite placers mined at Thung Kha (Tongkah Harbor) and from those mined by the Kamunting Tin Dredging Co. on the Phang—nga River in Changwat Phang—nga contain monazite. Only a small amount was found at Tongkah Harbor (Anderson, 1924), but reprocessed concentrate from the Phang-nga River contained 70 percent of monazite and 20 percent of tantalite after the ilmenite was removed (Buravas, 1951). An analysis of the re- processed concentrate showed 4 percent of Th02 and 45 percent of REan, equal to about 5.7 percent of ThOZ in the monazite. Monazite from cassiterite tailings at Phang—nga contains about 5.7 percent of T1102 (Thailand Delegation, 1956, p. 202). Very small amounts of marketable monazite con- centrates have been produced in Thailand, 18 short tons being reported for 1956, 64 short tons for 1957, and 1 short ton for 1958 (J. G. Parker, written commun., 1962). Output was apparently maintained during 1959~61, but data are not available. When prices justify the reprocessing of black sand waste from tin mining, or the recovery of monazite during mining, then possibly a greater output of monazite can be expected from Thailand. TIBET Monazite was detected in a concentrate made from sand in the Brahmaputra (Tsangpo) River near Chaksam in southeastern Tibet (LaTouche, 1918, p. 390). AUSTRALIA, NEW ZEALAND, AND ANTARCTICA Small amounts of monazite have been reported from every State in Australia and from New Zealand. Repeated attempts to find commercially acceptable monazite in the tin and tungsten placers in eastern 84 THE GEOLOGIC OCCURRENCE OF MONAZITE Australia have failed because much of the monazite in these deposits contains less than 2.0 percent of Th02. Low-thorium oxide monazite mined in the early 1900’s at the mouth of the Frazer River on King Island between Victoria and Tasmania was not wanted by industry, and the venture failed. An annual by- product output of as much as several hundred tons of monazite having 6.6 percent of Th02 has been maintained since 1948 at the extensive zircon-rutile placers along the southeast coast of Queensland and the northeast coast of New South Wales. It is very likely that beach placers will be discovered elsewhere along the coasts of Australia, particularly in areas where the shore deposits are formed from materials derived from plutonic metamorphic and igneous rocks. The coasts of Western Australia may be especially favorable. The occurrences in New Zealand are not economic sources of monazite, and the very few in Antarctica are mineralogical curiosities. AUSTRALIA NORTHERN TERRITORY Early reports mentioned several monazite-bearing veins at a place called variously Wolfram Creek (Mining J our., 1908) and Wolfram Camp (Australian Mining and Eng. Rev., 1909a, 1909b), which may be at or near Wolfram Hill, but more precise locations were not cited. Monazite from one of the veins, pre- sumably a wolframite-bearing quartz vein, contained 1.0 percent of ThO2 (Australian Mining and Eng. Rev., 1909a) . Monazite is a very scarce mineral in concentrates made from alluvium and stanniferous greisen at Nun- gado (Baker and Edwards, 1956a). Associated min- erals are tourmaline, staurolite, kyanite, epidote, zoisite, muscovite, and rarely hornblende, corundum, and green spinel. The deposit has no economic im— portance as a source for monazite. Other descriptions of monazite in Northern Territory have not been found, although thorium-bearing deposits of undeter— mined mineralogy are mentioned by Davidson (1956a). QUEENSLAND AND NEW SOUTH WALES Monazite occurs with zircon, rutile, ilmenite, gold, platinum, and osmiridium in beach and dune sands along the coast from the Johnstone River, 50 miles south of Cairns, Queensland, to Batemans Bay, 120 miles south of Sydney, New South Wales. Monazite was first found in the beach sands at Tweed Heads, New South Wales, in 1902 (Dunstan, B., 1905a, p. 11; 1905b) and in the Richmond River district, New South Wales, in 1903 (Mining Jour., 1903a, p. 182). In the late 1800’s and early 1900’s, the beach sands were intermittently mined for gold, platinum, cassiter- ite, and monazite (Ball, 1905; Raggatt, 1925, p. 16; Whitworth, 1931, p. 60) but generally failed to be a profitable source for these minerals. Later the coastal deposits were profitably mined for zircon and rutile. Placers on the shore have yielded a large part of the world’s commercial zircon and rutile since 1936 and from 1948 have been a source of monazite stockpiled by the Commonwealth Government (Poole, 1939, p. 216—220; Mining Jour., 1941a; Nye and others, 1950, p. 42; Mining J our., 1954b, p. 130; Blaskett and Hudson, 1955, p. 1; Brown and Dey, 1955, p. 256; Gardner, 1955, p. 9; Australia Dept. Natl. Devel., 1956, p. 92; Hudson, 1957, p. 1—3). Potential mona- zite output as a byproduct of the rutile mining was estimated by Hudson and Blaskett (1958, p. 161) to be 1,500 tons in 1956, but actual production was only 102 tons of high—grade concentrate owing, apparently, to a lack of separato‘ry equipment. The littoral monazite placers were reported by VVhitworth (1931, p. 59), Beasley (1948; 1950), and Gardner (1955) to be in present beaches, in old beaches buried below sand ridges parallel to the present shore, and in raised heathland or swamps. Rarely, the placers are below the present sea level at the seaward edge of the raised heathland. Large low-grade placers have been discovered in transgressive dunes elongated parallel to the direction of the prevailing wind. Dur— ing storms from the southeast the surf concentrates heavy minerals along the upper part of the beach where the minerals form wedge-shaped deposits 30—50 feet wide and at the most about 5 feet thick. The deposits extend along the length of the beach and thin out toward the ocean. They are thickest at the ends of beaches that thin northward against natural barriers. In good weather the sand dries and ulti- mately windblown sand covers the upper parts of the deposits, but the seaward part tends to be washed away unless it, too, is protectively buried. Deposits buried beneath sand ridges along old beaches are similar in appearance to the deposits on the present beaches. Several may be arranged en echelon with white sand between them. The raised heathland and swamps are elevated old beaches, flats, and dunes similar to those along the present coast except that original features have been modified by erosion. The submerged placers at the seaward edge of raised heathlands are formed by the erosion of the raised ground. Large low-grade placers in transgressive dunes are restricted to Stradbroke Island, Queensland, AUSTRALIA where beach deposits of heavy minerals, previously concentrated by the surf, have been eroded and redis- tributed by the wind. The sand along the beaches from Frazer Island, Queensland, southward to Batemans Bay, New South Wales, consists chiefly of quartz and was deposited mainly in Recent time. The heavy minerals in the beaches are zircon, rutile, and ilmenite, which to- gether constitute more than 90 percent of the concen- trate (table 22). Monazite, leucoxene, anatase, brook- ite, garnet, tourmaline, epidote, chlorite, green and brown spinel, chromite, magnetite, sapphire, pyrox— enes, hornblende, andalusite, staurolite, columbite (thitworth, 1931, p. 62—63), gold, platinum metals, and cassiterite make up the rest. The abundance of zircon and rutile is the greatest among beach placers. The immediate source of the quartz and heavy min- erals along, the coast near Sydney and north of the Clarence River is soft sandstone of Late Triassic (Whitworth, 1931, p. 73) and Jurassic age. Some of the ilmenite and magnetite, however, and the chromite 85 and platinum, were derived from mafic rocks. The ultimate source of the heavy minerals in the soft sandstone was shown by Gardner (1955, p. 21, 23—24) and Beasley (1950, p. 86, 91) to have been Upper Permian granitic batholiths in eastern Queensland and New South Wales, particularly in the New Eng- land area of New South Wales. Silicic phases of the granites and pneumatolytic dikes and veins contain small amounts of monazite and other heavy minerals which resemble in many physical aspects the heavy minerals in the Mesozoic and Recent sediments. Paleozoic graywacke exposed north of the Clarence River was examined at three localities and did not contain monazite (Beasley, 1950, p. 89—91). The ab- sence of monazite from the three samples is tentatively inferred by Beasley to indicate that the sequence of weakly metamorphosed Paleozoic graywacke, slate, quartzite, and phyllite into which the Permian gran- ites were intruded is devoid of monazite. South of the Clarence River, however, in the drainage basins of the Hastings, Manning, and Hunter Rivers, sand- TABLE 22.-—Mineralogical composition of concentrates from beach lacers, and reserves of monazite, along the South Pacific coast of Queensland and New outh Wales, Australia [Modified from Gardner (1955, tables 17, 29, 31—33). Symbol used: n.d., no data] Composition of concentrate (percent) Reserves (tons) Zircon Rutile Ilmenite Monazite Queensland Thursday Island near Cape York __________________________________ 4 0. 1 95 ? n.d. Johnstone River 50 miles south of Cairns 1 __________________________ 1. 4 1. 8 84 1. 2 n.d. Cannon Vale Beach 2 _____________________________________________ Trace __________ 62 ? n.d. Mackay (Blacks Beach)3 _________________________________________ 9 2 88 . 4 n.d. Facing Island ___________________________________________________ 7 9 80 ? n.d. Bustard Head ___________________________________________________ 34 4 61 n.d. n.d. Burnett Heads __________________________________________________ 3 2 94 ‘i’ n.d. Frazer Island Beach _____________________________________________ 25 17 57 . 6 500 Inskip Point ____________________________________________________ n.d n.d. n.d. n.d. 200 Double Island Point _____________________________________________ n.d n.d. n.d. n.d. 60 Noosa Head ____________________________________________________ 20 17 63 . 9 140 Maroochydore __________________________________________________ 35 16 49 . 3 n.d. Caloundra ______________________________________________________ 21 18 59 2. 0 n.d. Bribie Island ____________________________________________________ 22 18 58 1. 1 n.d. Moreton Island Beach ___________________________________________ 23 18 58 . 9 300 North Stradbroke Island Beach ______________________________________________________ 31 37 31 . 2 100 Parallel dunes _______________________________________________ 22 32 46 . 4 2, 400 Transgressive dunes (low-grade deposits) _______________________ 28 27 44 . 3 18, 000 South Stradbroke Island __________________________________________ 34 35 30 . 5 __________ Beach ______________________________________________________ n.d n.d n.d. n.d. 200 Foredune ___________________________________________________ n.d n.d n.d. n.d. 50 Parallel dunes _______________________________________________ n.d n.d n.d. n.d. 20 Southport, the Spit ______________________________________________ 38 37 24 . 6 n.d. Surfers Paradise, Wharf Road, Broadbeach, North Burleigh, North Nobby _______________________________________________________ 38 35 24 . 5 1, 020 Broadbeach _____________________________________________________ 38 36 25 . 5 n.d. North Burleigh __________________________________________________ 41 36 23 . 7 n.d. North Nobby to South Nobby ____________________________________ 41 33 26 . 7 160 Burlei h ________________________________________________________ 47 31 21 1. 1 200 Palm each _____________________________________________________ 41 36 23 . 5 250 Flat Rock Creek (Currumbin) _____________________________________ 40 37 23 . 5 40 Tugun Beach _______________________ , ____________________________ 42 32 25 . 5 110 See footnotes at end of table. 86 TABLE 22.——Mineralogical composition of concentrates from beach Queensland and New South THE GEOLOGIC OCCURRENCE OF MONAZITE lacers, and reserves of monazite, along the South Pacific coast of ales, Australta—Continued Composition of concentrate (percent) Reserves (tons) Zircon Rutile Ilmenite Monazite New South Wales Tweed Heads to Fingal Point _____________________________________ 49 29 22 0. 6 285 Fin a1 Point to Cudgen Point _____________________________________ 46 32 21 . 7 330 Cu gen Point to Norries Head (Cudgen Beach) _____________________ 51 28 21 . 5 3, 500 Norries Head to Hastings Point ___________________________________ 51 29 19 . 8 750 Norries Head to Hastings Point, inland ____________________________ 39 41 19 . 4 180 Hastings Point to Potts Point (Cudgera Beach) _____________________ 48 32 19 . 7 570 Potts Point to Brunswick Heads ___________________________________ 43 36 21 . 6 1, 140 Mooball Beach_______---__-_' ________________________________ 41 37 21 .5 n.d. Crabbes Creek Beach ........................................ 39 39 22 . 5 n.d. New Brighton Beach ......................................... 47 34 19 . 5 n.d. Brunswick Heads to Cape Byron (beach) ___________________________ 54 27 18 . 7 900 Cape Byron to Broken Head (Tallow Beach) ________________________ 53 28 18 . 6 1, 200 Broken Head to Lennox Head (Seven Mile Beach) ................... 53 28 18 . 8 180 Seven Mile Beach 1% miles inland ................................. 46 36 17 . 8 90 Ballina, beach top just south of the mouth of the Richmond River _____ 55 24 21 . 7 n.d. North of Evans Head 1—2 miles ___________________________________ 44 30 25 1. 0 n.d. Ballina to Evans Head ___________________________________________ n.d. n.d. n.d. n.d. 45 North of Woody Head Beach 2—5 miles ____________________________ 48 31 21 . 8 n.d. Evans Head to Woody Head Beach------_-_----_----_---_--__‘ ..... n.d. n.d. n.d. n.d. 210 Macaulays Lead _____________________________________________ 47 31 21 ' 1. 0 850 Cement Lead and west bank of Jerusalem Creek ________________ 46 32 22 . 5 110 Yamba _________________________________________________________ 58 29 13 . 3 n.d. North of W001i 8 miles ........................................... 63 27 10 . 3 n.d. Woolgoolga ..................................................... 34 41 24 1. 0 n.d. Laurieton area, south of Grants Head .............................. 40 39 20 1. 4 140 Swansea area ___________________________________________________ n.d. n.d. n.d. n.d. 150 Catherine Hill Bay __________________________________________ 50 42 6 1. 0 n.d. Caves Beach ________________________________________________ 33 44 22 2. 0 n.d. Perpendicular Point to Diamond Head _____________________________ n.d. n.d. n.d. n.d. 80 Terrigal ________________________________________________________ 38 38 21 2. 5 n.d. Bellambi Beach _________________________________________________ 38 37 24 . 7 n.d. Port Kembla ‘ __________________________________________________ 38 29 17 . 2 n.d. Bulli to Port Kembla ____________________________________________ n.d. n.d. n.d. n.d. 35 Shellharbour ____________________________________________________ 35 41 23 . 5 n.d. North of mouth of Shoalhaven River 1 mile _________________________ 22 18 59 . 8 n.d. Narooma _______________________________________________________ 12 7 80 . 16 n.d. Total ____________________________________________________________________________________________ 34, 495 l Tantalite, 0.9 percent. 1 Magnetite, 28 percent; hypersthene, 10 percent. stone of Carboniferous age is the main source for the Recent beach sands and heavy minerals. In their lower beds the Carboniferous sandstones were said by Gardner (1955, p. 22, 30—31) to have received heavy minerals from Devonian granitic rocks and in their upper beds to have received monazite and other heavy minerals from freshly unroofed Carboniferous granites. Efforts to relate the monazite in the Carboniferous, Mesozoic, and Recent sediments uniquely to stannif— erous granitic sources and veins of Devonian, Carbon- iferous, and Permian age seem to stem from the lack of a study of heavy minerals in the Paleozoic sedi— ments and in the less silicic phases of the granites, and from the many reports that monazite is associated with cassiterite and wolframite in the New England placers of New South Wales. Despite the strong physical resemblance of monazite from the alluvial tin placers to monazite from the beaches, the amount 3 The ilmenite contains a high proportion of magnetite. 4 Magnetite, 16 percent. of thorium oxide in the monazite is very different. As is shown below, monazite from the beaches aver- ages 6.6 percent of T1102, whereas that from the New England tin and tungsten placers contains about 1 percent of Th02. In View of the many analyses showing low-thorium oxide monazite in the New Eng- land cassiterite and wolframite placers, the monazite associated there with veins of cassiterite and wolf— ramite must also be low in thorium. Even the silicic granites, over which many tin placers lie and in which tin and tungsten minerals are found, have supplied no thorium-rich monazite to the tin placers. It is evident from analyses that the tin veins and pneuma- tolytic deposits, certainly, and the silicic granites, pos— sibly, have contributed for less monazite to the present beaches than have other sources. The other sources may include many of the Paleozoic granites other than the silicic and pneumatolytic phases. Possibly some monazite was contributed by Precambrian sources AUSTRALIA to the Paleozoic sedimentary hosts of the Devonian, Carboniferous, and Permian granites, and ultimately this monazite has been borne to the present beaches. In any event the source of the detrital monazite must contain monazite that has 6—10 times as much thorium as the monazite in the New England tin deposits. Monazite from Broken Head and Ballina in the Richmond River district, New South Wales, was shown by Mawson and Laby (1904, ,p. 387) to be radioactive. Monazite-bearing concentrates from beach sand at the mouth of the J ohnstone River, Queens- land, were reported to contain thorium oxide (Dun- stan, B., 1905a, p. 12). Analyses of two placer con- centrates, of undescribed mineral composition, from the mouth of the Richmond River near Broken Head showed the following percentages: (Analyst: Mingaye (1903, p. 222) Percent C6203 ___________________________________ 22. 42 22. 72 118.203 __________________________________ (Nd,Pr)203 ______________________________ l 22' 95 22' 78 Y203 ___________________________________ . 16 _____ Th02 ___________________________________ . 46 . 57 P205 ___________________________________ 18. 89 18. 94 Si02 ____________________________________ 6. 68 6. 48 A1203 ___________________________________ . 14 . 19 F8203 ___________________________________ 2. 08 1. 96 T102 ___________________________________ . 00 . 00 ZrOz ___________________________________ 15. 36 15. 44 T3205 __________________________________ 1.10 . 86 SnOz ___________________________________ 9. O3 9. 12 CaO ___________________________________ 1. 32 1. 40 MgO ___________________________________ Trace Trace MnO ___________________________________ Trace Trace H20 ____________________________________ . 10 . 12 Total _____________________________ 100. 69 100. 58 The amount of thorium oxide in monazite from beach placers between Southport, Queensland, and Byron Bay, New South Wales, was shown by Gard- ner (1955, p. 49) to be virtually constant at 6.6 i 0.3 percent. Radiometric comparisons between placer monazite from Byron Bay and monazite from the beaches at North Burleigh in Queensland and Cudgen and Woolgoolga in New South )Vales show that the monazite on these three beaches contains 7.3, 7.4, and 6.3 percent of T1102 (Gardner, 1955, p. 49). Partial and complete analyses of the rare earths and thorium oxide in placer monazite from the beach at Byron Bay have been made by Murat-a, Rose, Carron, and Glass (1957, p. 148). The original analysis is published as percentages of the total rare earths plus thorium oxide precipitate equal 100.6 percent. The composition has been recalculated to 68.6 percent of total REgO3 plus Th02 in the monazite (H. J. Rose, Jr., written commun, 1958) : 87 [Analystsz A, Wylie (1950, p. 165); B, Milli-43;? and Rose (in Murata and others, 1957 p. Percent A. B 06203 ____________________________________ 27. 2 1 28. 8 1.43203 ____________________________________ l5. 5 13. 8 Nd203 ____________________________________ 11. 9 11. 6 PI'203 _____________________________________ 3. 37 2 3.]. 8111203 ____________________________________ 2. 24 1. 9 Gd203 ____________________________________ n.d. 1.0 Y203 _____________________________________ n.d. . 9 Th0; _____________________________________ 7. 35 7. 5 1 C602. 3 ProOu. A chemical analysis of a concentrate containing 98 percent of monazite shows 7.1 percent of T1102, equiva- lent to 7.2 percent of Th02 in the pure mineral (Beasley, 1950, p. 80). Monazite of probably the same general composition, but from Tugun Beach about 6 miles south of Burleigh, has a specific gravity of 5.19 (Beasley, 1950, p. 80). Monazite has been reported from several localities on the Cape York Peninsula, Queensland. It was one of several minerals for which exploration was begun in the vicinity of the Pascoe River in 1956 (Mining Mag, 1956). Monazite makes up 1—9 percent of the heavy minerals in beach sand at the Hey River estuary near Weipa Mission on the Gulf of Carpentaria (Baker and Edwards, 1957a, p. 1). In the southeastern part of the Peninsula inland from Cairns monazite is a common accessory in gold, cassiterite, and wolframite placers. Four analyses of monazite from wolframite deposits near Cairns showed the following average percentage of thorium oxide and a specific gravity of 4.985: [Analystz Mmgaye in 1907 (1909. p. 282—283)] Percent RE203 _____________________________________ 1 69. 6 Th02 ______________________________________ l 4. 1 P205 ______________________________________ 25. 5 Total ________________________________ 99. 2 1 Average of 4 determinations. Monazite-rich concentrates from the mouth of the J ohnstone River contain 2.6 percent of ThOz and 56.1 percent of REgO3 (Dunstan, B., 1913, p. 753). Be- tween the J ohnstone River and Cairns at the Astrono— mer Mine in the Russell River gold field the alluvial concentrates consist chiefly of cassiterite, zircon, and ilmenite, but they also contain a little monazite, rutile, corundum, epidote, and anatase (Baker and Edwards, 1956b). Monazite was found in 1904 by B. Dunstan (1905a, p. 14—15; 1905b, p. 38) in tin and tungsten deposits in the Walsh and Tinaroo mineral fields southwest and west of Cairns. The monazite-bearing placers and the lodes are in granite close to contacts between the granite and slate and granite and quartz porphyry. The monazite contains about 65 percent 88 THE GEOLOGIC OCCURRENCE OF MONAZITE of RE203 and has a specific gravity of 5.04 (Dunstan, B., 1905a, p. 15). Various analyses have shown that the monazite from the Walsh and Tinaroo fields con- tains about 3 percent of ThOg, and it is said to be too'low in thorium oxide and insufficiently abundant to be of economic interest (MacDonald, 1906, p. 15; New Zealand Mines Rec, 1906, p. 402). Around 1905 a few tons of monazite had been saved as a byproduct at the wolframite mines, but none was sold (Dunstan, B., 1906, p. 157). Localities known to contain some monazite include Fingertown, California Creek, Emu Creek, several places on Nettle Creek, Bamford, 0rd, and near Coolgara (MacDonald, 1912, p. 15; Dun- stan, B., 1913, p. 753; Ball, 1915, p. 7). At Finger- town the monazite is associated with wolframite, bio- tite, and topaz in a quartz lode, and at California Creek it occurs with wolframite, molybdenite, cassit— erite, arsenopyrite, pyrite, mica, and quartz in greisen. Wolframite and cassiterite placers at California Creek contain monazite. On Emu Creek monazite occurs with cassiterite in placers 3 miles north of Fossil- brook, and with cassiterite, mica, chlorite, clay, and quartz at Emuford. The Nettle Creek occurrences, 10—14 miles north of Mount Garnet, are placers and an association of monazite with wolframite, cassiter- ite, tourmaline, and arsenopyrite in irregular masses of quartz in greisen. At Bamford the monazite ap- parently comes from wolframite placers in an area along the contact of biotite granite intrusive into porphyry (Ball, 1915, p. 59—64). Very small amounts of monazite are associated with cassiterite in placers in the Annan River tin field, Cooktown district, Queensland (Saint—Smith, 1915, p. 556—557; 1916, p. 165). Sparse grains of kyanite occur in the placers along Wallaby Creek in the Annan River tin field. A group of monazite-bearing pegmatite dikes are exposed in gneissic granite and micaceous hornblende schists about 5 miles southwest of Mount Isa in west— ern Queensland. From that point they extend at least 12 miles southward in a belt only about a mile wide. The dikes contain beryl, monazite, cassiterite. Inuscovite. tantalite. fluorite, and tourmaline (Blanch— ard and Hall, 1942, p. 35—37; David and Browne. 1950, p. 316; Shepherd, 1938, p. 95). Specimens of monazite from the Mica Creek pegmatites attain a maximum length of 4 inches (Connah, 1938). Four analyses show that the monazite contains from 5.73 to 6.22 percent of T1102 (Blanchard and Hall, 1942. p. 59). A sample of placer sand from Queensland, location and mode of occurrence unknown, was examined by the Imperial Institute [London] and was reported (Imp. Inst. [London], 1905, p. 233) to contain 1.2 percent of monazite. The Stanthorpe mineral field southwest of Brisbane and near the border of New South Wales has monazite- bearing cassiterite placers at Broadwater Creek in the Darling Downs (Dunstan, B., 1913, p. 753). The monazite first analyzed in New South Wales had a specific gravity of 5.001 and the following percentage of thorium oxide in small crystal fragments of detrital monazite from the Vegetable Creek tin fields: [Analyst: W. A. Dixon (in Wood, 1882, p. 26)] Percent 00203 _____________________________________ 36. 64 (La, Nd, Pr)203 _____________________________ 30. 21 Th02 ______________________________________ 1. 23 P205 ______________________________________ 25. 09 8102 _______________________________________ 3. 21 A1203 ______________________________________ 3. 11 MgO ______________________________________ Trace MnO ______________________________________ Trace Total ________________________________ 99. 49 This locality is about 25 miles north-northeast of Emmaville in the New England granitic area of north- eastern New South Wales. Monazite is a common but not abundant accessory in the cassiterite and wolframite deposits in the New England region (Game, 1912, p. 91 ; Raggatt, 1925, p. 16; David and Browne, 1950, p. 316). During the late 1800’s and early 1900’s, many samples of monazite from widely separated tin and tungsten placers in the region were analyzed in a search for commercially acceptable thorium ore, but only in rare samples did the monazite contain more than 2 percent of Th02 (Game, 1912, p. 91). One sample of monazite from Torrington and two samples from a point 20 miles west of Torring— ton were shown by Mawson and Laby (1904, p. 387) to contain 0.39, 1.5, and 1.8 percent of ThOz. Monazite associated with wolframite in the vicinity of Torrington was said to have only a trifling content of thorium oxide (Hintze, 1922, p. 344). Two samples of monazite- bearing alluvial sand from Torrington (Came, 1912, p. 92) contained 72.30 and 67.12 percent of RE203 and 0.38 and 0.71 percent of Th02. The first sample analyzed seems to have been virtually pure monazite, but the second is a concentrate shown to have 4.98 percent of metallic bismuth. The monazite in this concentrate probably had 0.75 or 0.80 percent of T1102. A sample of monazite from the vicinity of Battery Mountain between Torrington and Deepwater con- tained 70.71 percent of RE203 and 0.77 percent of Th02 (Carne, 1912, p. 91). Three analyses of monazite— bearing concentrates from The Gulf, northwest of Emmaville, showed from 0.31 to 0.65 percent of ThOz AUSTRALIA 89 (Game, 1912, p. 92) in material having possibly 40-100 percent of monazite. Estimates indicate that probably the amount of thorium oxide in the monazite in these was 0.35—16 percent. Five samples of monazite from The Gulf were reported by Mawson and Laby (1904, p. 387) to contain an average of 0.6 percent of Th0,,. Monazite that occurs as inclusions in feldspar and quartz in a wolframite-bearing pegmatitic vein at Blatherarm Creek in the Vegetable Creek tin field contained the following percentage of thorium oxide and had a specific gravity of 5.119: [Analyst Anderson (1904, p. 258—259)] Percent Ce203 _____________________________________ 35. 70 (La, Nd, Pr)203 ______________________________ 30. 73 Yan _______________________________________ Trace Th02 _______________________________________ 1. 63 P205 _______________________________________ 28. 20 SiOz _______________________________________ . 49 A1203, F8203 ________________________________ 2. 23 H20 _______________________________________ . 34 Total ________________________________ 99. 32 The vein is 8 inches wide, consists of orthoclase, quartz, biotite, wolframite, and monazite and fills a fracture in coarse biotite granite. Two monazite-bearing con- centrates from a stream 20 miles west of Torrington were shown by Game (1912, p. 92) to contain 1.56 and 1.81 percent of ThO2. Possibly these are the same samples reported as monazite by Mawson and Laby (1904, p. 387). Although neither concentrate seems to have consisted entirely of monazite, the content was perhaps 95 and 80 percent of monazite, and possibly the content of the monazite was about 1.6 and 2.2 percent of T1102, respectively. Monazite that had the following percentage of thorium oxide was found at Black Swamp, about 5 miles northwest of Torrington; it occurs with cassiterite and wolframite: Analyst: Mingaye in 1907 (1909, p. 283)] Percent 1115203 _____________________________________ 1 65. 23 Th02 ______________________________________ 1 4. 11 P205 ______________________________________ 25. 75 Total ________________________________ 95. 09 1 Average of two determinations. Monazite separated from an alluvial concentrate from Stannum contained the following percentage of thorium oxide: (Analyst: Wylie (1950, p. 165)] Percent 06203 _____________________________________ 25. 6 Lagos _____________________________________ 12. 6 Nd203 _____________________________________ 9. 90 PI‘203 ______________________________________ 2. 89 8111203 _____________________________________ 1. 99 ThOz ______________________________________ 6. 18 238—813—67—-7 At Warialda, New South Wales, monazite occurs in a vein of bismuth carbonate (Mawson and Laby, 1904, p. 387). Zircon sand 18 miles northeast of Dubbo, and gem placers 15 miles south of Oberon, near Mount Werong, contain monazite (Mingaye, 1909, p. 283). Monazite, thorite, and davidite occur as scattered disseminations and small veins in shear zones in meta- sedimentary gneiss and schist of early Precambrian age in the Thackaringa area of the Broken Hill dis- trict, New South Wales (Rayner, 1955, p. 62—69). In several places, granitic gneiss, amphibolite, and meta- morphosed limestone are present. The metamorphic rocks are of upper amphibolite grade and locally in- clude sillimanite gneiss. The metasedimentary rocks are migmatized, pegmatized, and widely intruded by aplite related to several ages of intrusion and replace- ment. About 95 percent of the area is covered with detrital sand, soil, rock fragments, and windblown sand. Thin layers of detrital heavy minerals, chiefly garnet, magnetite, ilmenite, and monazite, have been deposited along small watercourses in the western part of the district, but concentrations of monazite and other heavy minerals in the soil mantle have not been reported. No evidence is given for exploitable deposits of monazite in the area, but the assemblage of high-grade gneisses is here interpreted to suggest a possible wider presence of monazite in this district than has been reported. Monazite is a minor accessory detrital mineral in sedimentary rocks of the Lower Triassic Narrabeen Series which crops out along the coast of New South Wales between Stanwell Park and Tuggerah Lake (Culey, 1933, p. 344—359). Monazite was observed in 6 of 19 samples. It'was found only in sandstone and only in the vicinity of Terrigal and Pelican Point. Samples of tuff and shale from the same area did not contain monazite. The mineralogical composition of the monazite-bearing concentrates is given in table 23. Small amounts of detrital monazite from three sedi— mentary rocks of Permian age were reported by Car- roll (1940, p. 636—640) to have been found in outcrops west of Newcastle, New South Wales, and from depths of 6,265 to 6,291 feet in a test well at Kulnura about 37 miles southwest of Newcastle. The monazite oc- curs as sparse, well—rounded grains among the heavy minerals separated from hard gray compact calcareous Kulnura grit, hard gritty calcareous Muree tillite, and fine- to coarse—grained greenish slightly calcareous Ravensfield sandstone. The absolute amount of mona- zite in these rocks is very small. Table 24 shows the abundance of monazite and the associated heavy min— 90 TABLE 23.~—Mineralogical composition of monazite-bearing con- centrates from sandstones in the Narrabeen Series of Triassic age in New South Wales, Australia Analyst: Culey (1933, p. 361). Symbols used: A, abundant (46—75 percent); VC very common (26—45 percent); 0, common (6—25 percent); R, rare (1-5 percent); S, scarce (>1 percent); P, present; .. not determined; Ab, absent] 1 2 3 4 5 6 Heavy minerals in the sandstone_percent_ 0.05 0.07 0.03 0.03 0.1 0.01 Chalcopyrite ______ Ab Ab Ab Ab S Ab Garnet ___________ R S Ab R R R Magnetite _________ R Ab Ab Ab Ab Ab Picotite ___________ R C C C R R Spinel ____________ Ab Ab Ab Ab Ab S Anatase ___________ C C C C R C Rutile ____________ R R R R R R Zircon ____________ A A VC A A A Apatite ______ _ _ Ab Ab Ab R Ab Ab Ilmenite _____ _ _ _ R Ab R Ab C R Tourmaline ________ C C C C R C. Barite ____________ Ab C C Ab Ab Ab Brookite __________ Ab S Ab Ab S Ab Hypersthene _______ Ab Ab Ab Ab Ab S Biotite ________________________ Ab P Ab Ab Monazite _________ S S S R R S Muscovite _____________________ P P Ab Ab 1. Tudibaring (sandstone) 2. Avoca (sandstone). 3. Avoca (fine-grained sandstone). 4. Tertigal (sandstone). 5. Terrigal (green sandstone). 6. The Entrance (white sandstone). TABLE 24.—Mineralogical composition, in percent, of monazite- bearing concentrates from sedimentary rocks of Permian age in New South Wales, Australia [Analyst: Carroll (1940, p. 640). Symbols used: Ab, absent; L, large; M, medium; S, small; P, present] 1 2 3 4 5 6 7 8 Size of concentrate..._._______ M S S S L L L S Magnetite ..................... Ab P Ab P Ab Ab Ab Ab Ilmenite..- 33 17 11 35 3 6 5 6. 7 Leucoxene. 23 31 32 25 32 31 32 Pyrite ..... Ab P P Ab Ab Ab Zircon ........ 15 35 24 20 45 33 46 Tourmaline. _ 24 14 28 10 7 6. 5 Rutile Ab 2 1 2. 7 6 2 5 Anatase 2 . 1 Ab .2 2 3 2 Sphene 5 . 5 2 1 7 7 4 Garnet-.-- Ab Ab Ab 3. 5 5 10 . 3 Monazite" 5 . 1 .2 .2 1 . 7 7 Epidote--- 5 . 1 Ab Ab Ab Ab Ab Chlorite. _- Ab Ab Ab . 5 Ab Ab Ab Picotite. Ab Ab P . 4 3 . 4 Ab Barite _____ P Ab Ab Ab Ab Ab Ab Brookite. _ Ab Ab P Ab Ab Ab Ab Carbonate. P P P P Ab P Ab Mica ...... Ab Ab Ab Ab P P P 1-4.Ku1nura grit at depths of 6, 265, 6, 276 6, 290 6, 291 ft in a test well at Kulnura, about 37 miles southwest of Newcastle .Muroe tillite at Campbell’s Hill, West Maitiand. 6-7. Ravensfield sandstone at Ravensfield quarry, 3 miles due west of West Maitland. 8. Ravensfieid sandstone at Rutherford. erals in the 8 out of 13 samples that were monazite bearing. Virtually the same suites of heavy minerals was reported by Culey (1933, p. 361) from sandstone of Triassic age in the same area. Similarity in the suites of heavy minerals from sedimentary rocks of Permian THE GEOLOGIC OCCURRENCE OF MONAZITE and Triassic age in the same region was interpreted by Carroll (1940, p. 645—646) as showing that the sediments were derived from the same distributive province, which is thought to be an area underlain by an old sedimentary series and granite. This an- cestral distributive province may have been the source of monazite along the present coast. Repeated efforts to find commercially acceptable monazite in stream placers in Queensland and New South Wales have been unsuccessful (Raggatt, 1925, p. 16). Beach placers in both states, however, have yielded acceptable monazite since 1947. The amount of monazite recovered at the beaches between 1947 and 1952 is here estimated from Gardner’s account (1955, p. 68—102) to have been about 660 tons in 8,450 tons of concentrate. Washings made after storms and taken from the beach at the Spit between South Stradbroke Island and Southport, southern Queensland, have been the source of about 1,000 tons of concentrate per year since 1947. The concentrates contained perhaps 0.5 percent of monazite. Between Southport and Coolangatta, Queensland, 40 tons of monazite in high—grade concen- trates and 371 tons of monazite in low-grade concen— trates were produced between 1947 and 1952. Most of this output came from Broadbeach and North Burleigh, but some monazite was mined at Tugun, Burleigh, Palm Beach, Flat Rock Creek, and Main Beach. In northern New South Wales at Tallow Beach and Seven Mile Beach, 145 short tons of concentrates averaging more ‘ than 90 percent of monazite was produced between 1949 and the end of 1952. Prior to 1949 several hundred tons of concentrate containing 20 percent of monazite was stockpiled at Seven Mile Beach. The region be- tween Evans Head and Woody Head in northern New South Wales, particularly around Macaulays Lead, was worked between 1890 and 1900 for gold, the platinum metals, and cassiterite. Again between 1905 and 1910 the area was mined for these metals and monazite. No record of the early output of monazite was preserved. In 1950 about 200 tons of table concentrate having some monazite was stockpiled. About 102 tons of high-grade monazite concentrate was produced from the coastal deposits of Queensland and New South Wales in 1956 (Hudson and Blaskett, 1958, p. 161). Australian output of monazite between 1950 and . 1954, mined entirely from the beaches of Queensland and New South Wales, is given in table 25.‘ The pro- duction figures are very different from those supplied the writer by John G. Parker of the US. Bureau of Mines (table 26) . AUSTRALIA 91 The resources in monazite along the coast of Queens- land and New South Wales must considerably exceed the 34,495 tons given in table 22 as the reserves of these beaches. TABLE 25.—Monazite, in short tons, produced in New South Wales and Queensland, 1950—54 Compiled from Australia Bur. Mineral Resources, Geology and Geophysics, 1951; p. 15, 109; 1953, p. 98; 1954, p. 118 and from Carver, 1954, p. 8; 1955, p. 8] Concentrate produced Monazite produced New Queens- New Queens South land Total South land Total Wales Wales 1950 ____________ 33. 6 5. 6 39. 2 31. 4 4. 4 35. 8 1951 1 ___________ 35. 8 2. 3 38. 1 33. 6 2 35. 6 1952 ________________________ 128. 8 ____________ 118. 7 1953 ________________________ 220. 6 ____________ 202. 8 1954 2 _______________________ 88. 5 ____________ 78. 4 I Monazite sales were 49.3 short tons in 1951 and 128.8 short tons in 1952. 2 Estimate. TABLE 26.—Monazite, in short tons, produced in Australia, 1948—61 [J . G. Parker, U.S. Bureau of Mines (written mmmun., 1962)] High-grade Concen Low-grade Total concentrate trate concentrate 1948 ___________________________ 941. 9 ________ 941. 9 1949 _________ 208. 3 ________________ 208. 3 1950 _________ 174. 7 ________________ 174. 7 1951 ___________ 328. 2 ________ 45. 9 374. 1 1952 ___________________________ 128. 8 ________ 128. 8 1953 ___________________ 77. 3 ________ 206. 1 283. 4 1954 ___________________ 79. 5 ________ 118. 7 198. 2 1955 ___________________ 166. 9 ________ 49. 3 216. 2 1956 ___________________ 104. 2 ________ 163. 5 267. 7 1957 ___________________ 147. 8 ________________ 147. 8 1958 ___________________ 473. 8 ________________ 473. 8 1959 ___________________ 370. 7 ________________ 370. 7 1960 ___________________ 386. 0 ________________ 386. 0 1961 ___________________________ 1, 739. 0 ________ 1, 739. 0 Total ____________________________________ 5, 910. 6 SOUTH AUSTRALIA Low-thorium oxide monazite has been found in veins, disseminated deposits, and placers in South Australia. Most of the deposits are in Precambrian and Cambrian metasedimentary rocks in the Flinders-Mount Lofty Ranges which lead northward from Adelaide. None of the occurrences is a source for thorium. Small crystals of monazite from auriferous quartz at the Kings Bluff gold mine near Olary (Mawson, 1906, p. 192; Mining J0ur., 1909) were shown to contain the following percentage of thorium oxide: [Analystz Wylie (1950, p. 165)] Percent 06203 _____________________________________ 28. 4 Lagos _____________________________________ 19. 5 Nd203 _____________________________________ 12. 2 Pr203 ______________________________________ 3. 46 SmgOg _____________________________________ 2. 43 Th0; ______________________________________ . 18 Pneumatolytic disseminations of monazite, tourma— line, and apatite in corundum—mica schist were de- scribed by Mawson (1916, p. 263-264; Keystone, 1911) from an area of variously crushed and mylonitized orthogneiss, sillimanite schist, and cordierite-mica schist between Mount Pitts and Mount Painter (Maw- son, 1923, p. 376—379) in the Flinders Range. The monazite is ordinarily embedded in or surrounded by the mica, but where black tourmaline is abundant, the monazite is included in the tourmaline. Much of the monazite is euhedral. A clean concentrate of the mona- zite was analyzed by J. C. H. Mingaye (Mawson, 1916, p. 264) and was found to contain 0.16 percent of ThOz and 66.48 percent of RE203. About 4 miles southwest of Mount Painter, a crushed quartz-feldspar porphyry consisting of strained quartz and crushed orthoclase in a groundmass of fine-grained felsic granules contains common accessory magnetite and sphene and scarce small grains of honey-yellow to bottle—green monazite (Mawson, 1923, p. 379). Low—thorium oxide monazite also occurs in the Mount Painter area in some of the pegmatite dikes that contain radioactive minerals and in some of the schists invaded by the pegmatites (David and Browne, 1950, p. 317) . Thorium-poor monazite has been discovered in auri- ferous gravel at several places in the Mount Lofty Ranges and in cassiterite-bearing quartz from Glen- forth southeast of Tarcoola in/the south-central part of South Australia (David and Browne, 1950, p. 317). Thorium—rich monazite of no economic importance, occurs in Precambrian dikes of rutile-bearing albite pegmatite in slightly metamorphosed quartzose schists in the Normanville district of the Flinders Range about 40 miles south of Adelaide. At the Yankalilla gorge 4.5 miles southwest of N ormanville, the monazite is most abundant in thick envelopes of biotite that enclose the pegmatites (Thomas, 1924, p. 259—263). The monazite is typically formed as augen which reach a maximum size of 6 by 4 by 3 inches and are elongated parallel to the strike of the schists. Euhedral crystals are scarce. Autoradiographs of large polished pieces of monazite clearly outline areas of diiferent intensity of radioactivity. The most radioactive areas cor- respond to darker colored parts of the specimen. In one sample the more radioactive parts were enclosed by well-defined boundaries that may have been crystal faces, but in most pieces of monazite the zones of greatest radioactivity are irregularly distributed. Anal- 92 THE GEOLOGIC OCCURRENCE OF MONAZITE ysis of this monazite, specific gravity of 4.95, disclosed the following percentage of thorium oxide: [Analystz Thomas (1924, p. 262; see also Holmes, Arthur, 1931, p. 387)} Percent Percent Ce203 _______________ 25. 09 TiOz ________________ 1. 70 La203 (group) ________ 24. 32 Ta205 _______________ . 00 Y203 (group) ________ 4. 00 CaO ________________ 2. 60 Th02 _______________ 10. 7 PbO ________________ . 55 U303 ________________ . 00 1120— ______________ I . 40 P205 ________________ 26. 88 H20+ ______________ 1 1. 52 S102 ________________ 1. 65 i —~—»-— A1203 _______________ . 00 ' Total _________ 100. 26 Fe203 _______________ . 85 IRelatively high percentage of combined water is regarded by Thomas as con- firming microscopic evidence that the monazite is altered. Combined water is interpreted as partial hydration of the rare-earth bases and simultaneous leaching of phosphoric acid. Another analysis of monazite from a rutile-bearing pegmatite in the N ormanville district showed the fol— lowing percentage of thorium oxide: [Analystz Wylie (1950, p. 165)] Percent C8203 _____________________________________ 21. 9 143.203 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10 5 Nd203 _______________________________________ 11. 7 Pr203 ______________________________________ 3. 03 8111203 ______________________________________ 2. 23 Th0; ______________________________________ 19. 4 At Myponga Hill along the road between Yankalilla and Adelaide, isolated elongate masses of monazite as much as 2 inches long occur in what was described as a shear zone in metasedimentary rocks of Precambrian age (Rowley, 1956, p. 63). The possible sheared zone is between two veins composed of ilmenite and hema- tite. It is about 3 feet wide and consists of a soft mix- ture of talc, mica, and tremolite asbestos containing the elongate pieces of monazite. Although the talcose mix— ture extends beyond the ilmenite-hematite veins, the monazite is restricted to the material between the veins. Radiometric analysis of selected pieces of the monazite indicated that the monazite contains about 8 percent of Th0... Placer monazite with more than 8.0 percent of Th02 was found at Daws Diggings on Kangaroo Island southwest of Adelaide (David and Browne, 1950, p. 317). The monazite is associated with rutile, zircon, corundum, kyanite, tourmaline, and gold. The abun- dance of thorium oxide and the associated minerals and the geographic proximity to the Normanville deposits suggest that the monazite on Kangaroo Island may have been derived from terrain similar to that at Normanville. Rutile-bearing pegmatite dikes in hornfels and schists at Strathalbyn, South Australia, contain small crystals of monazite (Wilson, A. F., 1943) which com— monly occur at the contact between the dikes and wall- rocks, especially where black tourmaline is an accessory in the dike. No analysis is given. Monazite has not been mined in South Australia. TASMANIA Monazite seemingly was first noticed in Tasmania between 1893 and 1896; it was not mentioned by Petterd (1894) in 1893 when he listed the minerals known to occur in Tasmania but was mentioned in a paper read in 1896 (Petterd, 1897, p. 27). Its discovery was attributed by Petterd (1910, p. 121) to Prof. Stelzner of the Mining School at Freiberg, Saxony, who observed monazite in ore from the Mount Bischofl district. By 1902 Petterd (1902, p. 82) wrote that monazite had been found in most of the streams drain- ing granite in Tasmania. Most Tasmanian fluvial tin placers contain monazite. Monazite has been found on the beaches, and it occurs in placers on King Island between Victoria and Tasmania. Monazite-bearing cassiterite placers in northeastern Tasmania are associated with outcrops of Devonian porphyritic biotite granodiorite and muscovite-biotite granite intrusive into Silurian and older slates and quartzites (David and Browne, 1950, p. 292). Along the Ringarooma River (Nye, P. B., 1925, p. 28) and in the Scottsdale district (Petterd, 1910, p. 121), the monazite and cassiterite are accompanied by tourmaline topaz, corundum, and zircon, all apparently derived from the granodiorite and granite. Monazite from a placer in the Scottsdale district was shown to contain the following percentage of thorium oxide: (Analyst: Wylie (1950, p. 165)] Percent 06203 _____________________________________ 26. 7 Lagos _____________________________________ 14. 4 Nd203 _____________________________________ 11. 0 PrzOg ______________________________________ 3. 23 Sm203 _____________________________________ 2. 22 Th02 ______________________________________ 7. 29 According to Petterd (1910, p. 121), attempted mining of the placer monazite in the Scottsdale area failed in the early 1900’s because the monazite contained only 2 percent of Th02. Some of the lode mines in the Moina, Mount Claude, and Lorinna areas around the Forth River in the north-central part of Tasmania were reported (Reid, A. M., 1919, p. 47—48) to have monazite. The mineral occurs in quartz veins with cassiterite, wolframite, bismuthinite, fluorite, topaz, and beryl. Reid stated that no analyses of this monazite were made because other Tasmanian monazites analyzed prior to this study had less than 3 percent of Th02 and were unac- ceptable in commerce. Black sand, reported to contain titaniferous minerals, zircon, monazite, cassiterite and gold, the last two minerals in commercial abundance, was being mined AUSTRALIA 93 near Low Head on the north coast of Tasmania in 1941 (Mining Jour., 1941a). A concentrate was prepared at the beach using Wilfley tables and sea water for the processing, and the concentrate was shipped to Mel- bourne for further treatment. Output of monazite, if any, is not known. The Stanley River tin field north of Zeehan in western Tasmania contains detrital monazite, but monazite has not been observed in the cassiterite veins (Waterhouse, 1914, p. 113—114; Petterd, 1903, p. 28; Imp. Inst. [London], 1925; Engineer, 1925). The detrital monazite is thought to originate as dissemi- nated grains in the local granite, for it was discovered in many short creeks heading in and flowing across granite. No analyses are given for the monazite; Waterhouse inferred it to have but little thorium oxide. Monazite is rather abundant at the North Heemskirk tin field (David and Browne, 1950, p. 316), but in the South Heemskirk placers it is an uncommon accessory (Waterhouse, 1916, p. 212). In the Mount Bischofl" tin field, monazite derived from granite intrusive into slates (Twelvetrees and Petterd, 1898, p. 120) is widely distributed in the placers of the South Bischofl' area. It contains from 2.5 to 3.0 percent of T1102 (Reid, A. M., 1923, p. 53). Ocher—yellow crystals of monazite encrusting wolframite have been found in quartz ore from Mount Bischoff (Hintze, 1922, p. 344). Monazite was reported to occur at Mount Stormont (Mining J our., 1941b), but details are lacking. It is also found in the Yellow Band Plains (Nye and Blake, 1938, p. 96) and in the Khaki Mine at the foot of the Meredith Range (Petterd, 1910, p. 121). The beach sands of King Island in Bass Strait be- tween Victoria and Tasmania were the source of mona- zite found to contain the following percentage of thorium oxide: [Analystz Wylie (1950, p. 165)] Percent 06203 _____________________________________ 28. 3 La203 _____________________________________ 16. 8 ngOa _____________________________________ 11. 0 P1303 ______________________________________ 3. 12 8111203 _____________________________________ 2. 72 Th0; ______________________________________ 6. 09 In the early 1900’s, black sand at the mouth of the Frazer River was treated for monazite and cassiterite. According to Debenham (1910, p. 574), “the monazite was separated without great difficulty, but its low percentage of thorium forbade its ready sale, and the tin concentrates did not pay for the cost of working.” The Frazer River drains a broad area of alluvium covering slates and schists (Debenham, 1910, p. 572); thus, the ultimate source of the monazite is not known. N 0 record of the production of monazite at the Frazer River is given. In the eastern part of Tasmania, monazite occurs on the south side of Mount Stronach in the Pioneer tin mine (Petterd, 1903, p. 28; 1910, p. 121) and on the east coast (Nye and Blake, 1938, p. 96). VICTORIA Placer monazite has been found on the beaches of eastern and southern Victoria and in streams in the northern, eastern, and western parts of the State. Layers of black sand along the beach 3 miles south- west of Mallacoota Inlet, East Gippsland, Victoria, contain 15—70 percent of heavy minerals (Baker and Edwards, 1956c; 1957b, p. 1). In five samples, mona- zite made up 0.2-1.0 percent and averaged 0.4 percent of the black sand. Monazite, separated from the zircon and rutile with which it occurs on the beach at Cape Everard southwest of Mallacoota Inlet, was shown to contain the following percentage of thorium oxide : [Analystz Wylie (1950, p. 165)] Percent 06203 _____________________________________ 26 6 148.203 _____________________________________ 15. 7 Nd203 _____________________________________ 10. 6 PI‘203 ______________________________________ 2. 76 Sm203 _____________________________________ 2. 36 Th02 ______________________________________ 5. 20 The source may be granitic rocks and invaded Paleozoic sedimentary rocks at and north of the Cape. Orange—yellow alluvial monazite occurs with green epidote and small amounts of ilmenite, magnetite, and scarce sapphires in the upper valley of Pinch Swamp Creek in the Bonang district of East Gippsland (Copland, 1905, p. 3—6). The monazite-bearing allu- vium is a coarse gravel of quartz and greenstone bound by blue clay. Throughout the valley where monazite is found the gravel rests on decomposed diorite. Monazite is disseminated through the diorite and occurs in the contact—metamorphosed Ordovician slate into which the diorite is intruded. The monazite contains 6.6 percent of T1102, 29.0 percent of Ce203, and 27.4 percent of other rare earths. Elsewhere in eastern Victoria, monazite has been found in gravel in the Koetong area of East Gippsland, in the Mitta Mitta River southeast of Albury, at Bethanga, and in South Gippsland (David and Browne, 1950, p. 316). , Along the south coast of Victoria, small amounts of monazite have been reported from Point Addis, Phillip Island, and the Mornington Peninsula. At Point Addis, black beach sand was described (Baker and Edwards, 1956d, p. 1) as consisting dominantly of hematite, maghemite, and limonite mixed with some ilmenite, rutile, and pyrite and about 1 percent of minor accessories which are principally zircon, kyanite, 94 tourmaline, and monazite. Black sand of little eco- nomic value is found along the beaches of Phillip Island (Beasley, 1957). Six concentrates from the deposits contain 67 percent or more of limonite, mag- netite, and ilmenite. Olivine makes up 32—104 percent of the concentrate in each of the six samples. Zircon, augite, rutile, leucoxene, tourmaline, epidote, topaz, spinel, sphene, and garnet are present. A trace of monazite was seen in three of the six concentrates. Most of the heavy minerals come from Tertiary vol- canic rocks that crop out near the beaches, but the immediate source of the monazite, zircon, rutile, tour- maline, topaz, epidote, garnet, spinel, and sphene are Jurassic and Tertiary sedimentary rocks on the island and the adjacent mainland. Beach sands from the Mornington Peninsula contain 3.7 percent of heavy minerals, but monazite is scarce (Baker and Edwards, 1956e, p. 1). Concentrates consist chiefly of ilmenite, with some magnetite and hematite, a little zircon, tourmaline, rutile, and leucoxene, and a trace of monazite. Heavy-mineral sands are not naturally concentrated in sufficient quantity on these southern beaches to be economically recoverable, nevertheless monazite-bear- ing sands are present on bay and ocean beaches. Mona- zite was found in 7 out of 11 samples of heavy-mineral beach sand collected by Baker (1945, p. 11—16) from about Kilcunda. The composition of these monazite- bearing concentrates is shown in table 27. Magnetite and ilmenite are generally the chief components, but at Ricketts Point the concentrates consist mainly of ilmenite and zircon, and at Torquay mainly of mag- netite and zircon. At Balnarring, Point Hayley, and Kilcunda the natural concentrates contain a great TABLE 27.—Mineralogical composition of monazite—bearing con- centrates from bay and ocean beaches of Victoria, Australia [Analystz Baker (1945, table 2, p. 16). Symbols used: P, present; Ab, absent] Bay beaches Ocean beaches Saint Ricketts Davey’s Bal- Tor- Point Kil- Kilda Point Bay narring quay Hayley cunda Anatase ______________ P Ab P Ab Ab Ab Ab Augite- . _ . ______ P Ab Ab P Ab P P Brookite_. ______ Ab Ab Ab Ab Ab Ab P Cassiterite ___________ P Ab Ab P P Ab Ab Clinozoisite __________ P Ab P Ab Ab Ab Ab Epidote ______________ Ab Ab Ab P Ab P Garnet _______________ Ab P P P Ab P P Hypersthene _ . _ P A b Ab P Ab P P Ilmenite ............. P P P P Ab P P Kyanite ............. Ab Ab Ab P Ab Ab Ab Leucoxene ........... P P Ab P P P P Limonite ............ Ab P P Ab Ab P P Magnetite ___________ P Ab P Ab P P P Monazite ............ P P P P P P P Olivine. _ . _ _ _ P Ab Ab Ab Ab Ab P Rutile ............... Ab P P P P P P Sphene ______________ Ab Ab Ab Ab Ab P Ab Spine] _______________ Ab Ab Ab Ab Ab P P Staurolite ____________ Ab P Ab P Ab P Ab Topaz _______________ Ab Ab Ab P Ab P P Tourmaline __________ P P Ab Ab P P P Zircon _______________ P P P P P P P THE GEOLOGIC OCCURRENCE OF MONAZITE assortment of heavy minerals, but except for magnetite, ilmenite, and zircon, the other minerals, including monazite, are represented by only a few grains each. The order of abundance is magnetite, ilmenite, zircon, rutile, garnet, and tourmaline. Monazite occurs as pale-lemon-yellow oval grains and is uncommon in all samples. The number of cycles of erosion and transportation of the heavy minerals at each beach was not deter- mined by Baker (1945, p. 16), but he inferred that some species may have participated in five or more cycles. The heavy minerals at Saint Kilda are thought to come partly from the drainage basin of the Yarra River. At Ricketts Point they «are derived from Red Beds of Tertiary age, and at Davey’s Bay from fer- ruginous sedimentary rocks of Tertiary age and from granodiorite. Sources for the heavy minerals at Balnarring include Tertiary basalt, Devonian granitic rocks, and metasedimentary rocks. Around Torquay the main sources were sedimentary rocks of Tertiary age. At Point Hayley and Kilcunda the source is arkose of Jurassic age, but at Kilcunda some magnetite and ilmenite may come from dikes of olivine basalt that cut the Jurassic sedimentary rocks (Baker, 1945, p. 17—18). Monazite is present in variable quantities in cas- siterite-bearing concentrates from stream sand and residual soil from granite in the upper part of the drainage basin of the La Trobe River (Baker, 1959). A monazite-bearing volcanic ash bed of probable Pleistocene age is associated with limestone in small lake deposits exposed in three quarries 1—2 miles east of Coimadai about 35 miles northwest of Melbourne (Coulson, 1924, p. 169-174). The volcanic ash contains many fragments of slate, shale, and sandstone. The ash was inferred by Coulson to have been deposited simultaneously with stream-transported debris in the lake basins. Quartz is the most abundant mineral in the ash; biotite and feldspar are present, and picotite, monazite, and pyrite are sparsely present. This is the only volcanic ash, exclusive of carbonatite complexes, in which monazite has been observed. No evidence is presented to show whether the monazite is of pyro- clastic origin or was derived from land waste and brought into the lake deposits by the streams. Monazite was reported from Stawell and Nhill in the southern Mallee country of western Victoria (David and Browne, 1950, p. 316). No commercial production of monazite was recorded for Victoria. WESTERN AUS’I’RALIA The occurrences of monazite in Western Australia have been summarized by Simpson (1952, p. 248—252) AUSTRALIA in his text on the mineralogy of the State from discus- sions previously published (Simpson, 1912a; 1912b, p. 94; 1914, p. 43; and 1919, p. 5). The following material, unless otherwise noted, is taken from Simp- son’s summary descriptions. Monazite occurs as an accessory mineral in plutonic silicic igneous and metamorphic rocks, in consolidated and unconsolidated sediments, and in soils of Western Australia. It has been found in lake sediments, in the beds of streams, and along the oceanic beaches, but none of these occurrences has been shown to be an industrial source for monazite. Precambrian gneiss in the Yilgarn gold field in the southern part of the State, particularly gneiss exposed around Southern Cross, contains monazite. Heavy residues from the overlying soil are commonly mona- zite bearing. In the Pilbara gold field (Mawson and Laby, 1904, p. 387) in the northern part of the State, concentrates from the upper Precambrian fluvioglacial Nullagine conglomerate at Nullagine contain monazite, barite, zircon, xenotime, rutile, cassiterite, magnetite, ilmenite, chromite, tantalite, pyrite, and gold. Permian sedimentary rocks at Wandagee (Wandagee Station) in the northwestern part of the State locally contain detrital grains of monazite (Higgins and Carroll, 1940, p. 145—156) . Sixteen out of twenty—three samples of fine—grained argillaceous and micaceous sandstone, sandy shale, and coarse—grained sandstone contained monazite (table 28). In most of the rocks the concentrate makes up less than 1 percent of the 95 total weight, and monazite is less than 1 percent of the concentrate. At Wandagee Hill, coarse-grained sand- stone contains as much as 2 percent of heavy minerals, and monazite constitutes 3 percent of the concentrate. In each of the samples the monazite forms round yellowish—green grains. Metamorphic and igneous rocks of Precambrian age are thought to be the source of the detrital monazite in these sandstones. Sedimentary rocks of Permian age at the Irwin River in the southwestern part of the State contain small amounts of detrital monazite. The monazite is most abundant in sediments adjacent to seams of coal. The Donnybrook sandstone of Triassic age and derived soils in the southwestern- part of Western Australia are monazite bearing. Examination of the heavy residues from six samples of greensand and chalk of Cretaceous age exposed around Gingin in the southwestern part of the State disclosed a small amount of detrital monazite in one specimen of greensand from Poison Hill, 3.7 miles north-northwest of Gingin (Carroll, 1941, p. 87—90). Abundant ilmenite and magnetite make up most of the heavy minerals in the monazite-bearing sample. Zircon, tourmaline, rutile, kyanite, sillimanite, sphene, spine], and anatase are also present. The grains are much worn. Similar but unworn heavy minerals occur in a belt of garnetiferous staurolite schist and gneiss, kyanite schist and gneiss, and sillimanite schist and gneiss of Precambrian age exposed east of Gingin. These old gneisses were tentatively suggested to be the TABLE 28.——Mineralogical composition of monazite-bearing concentrates from Permian sedimentary rocks in the vicinity of Wandagee, Western Australia [Modified from mineralogical analyses by Higgins and Carroll (1940, p. 149); P, present] Heavy minerals (frequency percent) Con- . cen- Sample and locality trate 1 Mag- Ilmen- Limonite Tour- Ana- Brook- Mon- Chlo- Epi- Staur- netite ite and Zircon maline Rutile tase ite Garnet Sphene azite rite Mica dote olite Spinel leucoxene 1. North side of Minilya 0.71 P 5 24 39 2 4 P 20 1 1 ______________ P ________ P River. 2. North side of Carn- Tr. P 3 19 56 4 4 1 5 5 2 ______________ P ________________ arvon Road. 3. North side of Minilya . 55 P 3 22 50 6 9 P P 5 5 River. 4. South side of Carn- .45 P 1 34 32 5 9 P ________ 14 2 arvon Road. 5. North side of Minilya . 30 P 1 28 44 7 6 P P 10 1 River. 6. North side of Carn- 1. 00 P 1 46 26 2 3 P ________ 14 3 7. .80 P 4 40 22 5 3 21 3 8. Do__ __-, .57 P 11 28 27 3 3 25 P 9. North side of Minilya Tr. P 7 33 34 5 2 13 1 River. 10. South side of Minilya Tr. P 6 26 19 6 4 1 P 35 P River. 11. North side of Carn- Tr. P l 15 40 3 5 ________________ 34 P arvon Road. 12. South side of Minilya Tr. P 1 17 46 1 7 P ________ 26 P River. 13. Wandagee Hill ....... 1. 31 P 2 55 10 2 1 1 14. Do _______________ 1. 20 P 23 36 25 4 P 4 15. 2. 00 P 24 , 36 28 1 2 2 16. Do _______________ .13 P 22 30 31 4 6 1 1 Expressed as weight percent of sediment from which it came. Samples 1—8 are ferruginous, calcareous, and micaceous sandstone, rare sandy shale. Sample 9 is calcareous fine-grained sandstone. Sample 10 is gy siferous shale. Samples 11 an 12 are massive argillaceous and micaceous sandstone. Samples 13 through 16 are coarse-grained sandstone. 96 THE GEOLOGIC OCCURRENCE OF MONAZITE source of the heavy minerals in the greensand at Poison Hill (Carroll, 1941, p. 90). Detrital monazite has been found in the soil at Hill- side (Hillside Station), Mount Francisco, and Split Rock (Split Rock Station) in the northwestern part of the State, at Perth in the southwest, and at Kookynie in the central part. At Hillside the mona— zite is associated with detrital quartz, feldspar, mic— rolite, and samarskite. In the occurrence at Mount Francisco, monazite is mixed with cassiterite and tanteuxenite in clayey and gravelly soil which marks the outcrop of two pegmatite dikes in granite. Angu- lar fragments of monazite found in the soil at Split Rock, about 13 miles north of Eleys Well (Eleys), seem to have had their source in a nearby pegmatite. The beach sand and the soils derived from limestone exposed along the coast near Perth contain well- rounded particles of monazite. Sparse grains of mona- zite have been detected among the heavy minerals recovered from soils around Kookynie, but the source has not been described. Detrital monazite of unknown source has been found at Pilgangoora in the northwestern part of the State. Elsewhere in the northwest it has been discovered with garnet and ilmenite at Tabba-Tabba, with yttrotanta— lite at Tambourah, and at a point 10 miles south of Wodgina. In the central part of Western Australia a little monazite was found with gold at Eucalyptus, and some monazite was identified in material taken from the road between Esperance and Coolgardie about 10 miles south of Sheep Rock. Black sand from Lake Jasper and the Donnelly River in the Nelson District contains a little monazite and kyanite but consists dominantly of ilmenite. None of these deposits seems to be a commercial source for monazite (Maitland, 1904). Monazite is a common accessory mineral in cassit- erite-bearing streams throughout Western Australia. Indeed, 8 of the 11 alluvial deposits reported by Simpson (1919, p. 5; 1952, p. 248—252) to contain monazite are tin placers. In the northwestern part of the State, monazite occurs with cassiterite in a placer about 10 miles southwest of Abydos (Abydos Homestead). Monazite is very common in the tin placers at Shaw and Cooglegong (Simpson, 1912b, p. 94; 1914, p. 42) where it is accompanied by cassit— erite, fergusonite, euxenite, and gadolinite and is derived from local Precambrian pegmatites. Mona- zite, cassiterite, and tantalopolycrase occur in a placer at Eleys. Concentrates from the gold and cassiterite placers along Friendly Creek contain monazite. At Globe Hill monazite is concentrated with cassiterite and ilmenorutile in stream placers. Cassiterite, mona- zite, and columbite occur together in alluvial deposits at Moolyella. Coarse-grained cassiterite, garnet, co- lumbite, and monazite are found in the tin placers at the southeast end of the Poona area in the Murchi- son gold field (Simpson, 1912b, p. 94). In the south- western part of the State, monazite is associated with abundant zircon and cassiterite at Greenbushes. Tin— free monazite-bearing concentrates were reported from the Deep River, Manjimup, and the Swan River. Monazite makes up less than 10 percent of the concen- trates from the Deep River, which consist principally of garnet, ilmenite, zircon, and a little spinel. The concentrate from Manjimup consists mainly of ilmenite and zircon but has 15 percent of monazite and some kyanite, tourmaline, garnet, rutile, gold, and spinel. Black sand from the Swan River near Perth contains a little monazite similar in size and color to that in the soil overlying the coastal limestone. Concentrates from beach sand on the north coast of Western Australia contain 0.1 percent of monazite, 52 percent of zircon, 27 percent of tourmaline, 10 per- cent of opaque minerals, 4 percent of rutile, and small amounts of epidote, hornblende, topaz, and zoisite (Baker, 1957). Concentrates from Capel on the south- west coast that have a similar composition have domi- nant ilmenite, 0.1—1.2 percent of monazite, and small amounts of tourmaline, epidote, cassiterite, staurolite, kyanite, garnet, zoisite, corundum, and spinel (Baker and Edwards, 1956f, p. 2—5). Small amounts of monazite are present in 5 out of 15 samples of Recent sand from beaches at Koombana Bay and the Indian Ocean near Bunbury (Carroll, 1939, p. 96—102). The beach sands at and immediately east of Bunbury overlie tholeiite lava flows of Terti- ary age (table 29; samples 1, 2, 4). Elsewhere the beach sands overlie sand and clay of coastal plain for- mations of Recent and older age (samples 3, 5). Inland from the coastal plain are gneisses, granites, and green- stone of Precambrian age, and about 15 miles south of Bunbury sandstone of probable Permian age crops out. The heavy minerals in the beach sands, which are locally concentrated into small placers, come from these diverse sources. The abraded character of the zircon, tourmaline, kyanite, and monazite was inter- preted by Carroll (1939, p. 102) to indicate that those mineral grains have passed through several cycles of sedimentation after their release from the Precambrian rocks. NEW ZEALAND 97 TABLE 29.——Mineralogical composition of monazite-bearing con- centrates from beach sand near Bunbury, Western Australia [Analystz Carroll (1939, p. 101—102). Symbols used: VA, very abundant; A, abun- dant; P, present; Ab, absent] l 2 3 4 5 Sieve fraction______ +250 +250 +115 +32 +250 +250 Magnetite _________ VA Ab Ab VA A Ilmenite _ _ VA A A VA VA Calcite ______ P P P Ab Ab Amphibole ________ P A P P P Tourmaline ________ Ab Ab Ab P P Ab Leucoxene _________ P P P P P Ab Garnet ____________ P P P P P Ab Epidote ___________ P P P P P Ab Kyanite ___________ Ab Ab P P P Ab Zircon ____________ P A P P A A Rutile ____________ P P P P P P Monazite _________ P P P P P P Sillimanite ________ Ab P Ab Ab Ab Ab Sphene ___________ Ab P Ab Ab Ab P Apatite ___________ Ab Ab Ab Ab P Ab Pyroxene __________ Ab P Ab Ab Ab Ab Spine] ____________ Ab Ab Ab Ab Ab P Topaz(?) __________ Ab P Ab Ab Ab Ab 1. Shore of Koombana Bay 1.6 miles east-northeast oi the center of Bunbury. 2. Shore of Koombana Bay 1 mile east oi the center of Bunbury. 3. Shore of the Indian Ocean 0.6 mile southwest of the center of Bunbury. 4. Shore of the Indian Ocean 0.4 mile southwest of the center of Bunbury. 5. Shore of Koombana Bay 2.1 miles northeast o! the center of Bunbury. The composition of placer monazite from Western Australia has been recorded by Simpson (1912a, p. 45—47; 1912b, p. 95; 1914, p. 43; 1919, p. 5) and Wylie (1950, p. 165). A complete analysis and three partial analyses of monazite from tin placers at Moolyella in the Pilbara gold field, where the monazite comes from pegmatite intruded into Precambrianmetasedi- mentary rocks, greenstones, and unmetamorphosed sediments, disclose 5.02—5.24 percent of Th02. Chemical analyses, in percent, of monazite from tin placers at Moolyella, Western Australia [Analystsz 1—3, I. H. Brooking; 4, J. C. H. Mlngaye] 08203 __________________ (La, Nd, Pr) 203 _________ 1 Specific gravity, 5.26. In the same general area at Cooglegong placer, monazite derived from pegmatite contained from 3.80 238—813—67—8 to 5.93 percent of Th02 in three analyses. A complete and a partial analysis showed the following percentages of thorium oxide and a specific gravity of 5.30 for the monazite: [Analystsz A, Simpson (1919, p. 5); B, J. H. Brooking (in Simpson, 1919, p. 5)] Percent A B 08203 ____________________________________ 31.10 (La, Nd, P1920; ___________________________ 34. 26 53. 19 Y203 _____________________________________ . 04 Th0; _____________________________________ 3. 80 4. 38 U0; ______________________________________ Trace _____ F8203 ____________________________________ . 42 _____ A1203 _____________________________________ . 64 _____ CaO _____________________________________ . 34 _____ MgO _____________________________________ Trace _____ PbO _____________________________________ Trace _____ P205 _____________________________________ 26. 89 _____ SiO; _____________________________________ 1. 96 _____ H20 + ___________________________________ 58 ..... Total ______________________________ 100. 03 _____ An analysis of the rare earths and thorium oxide in Cooglegong placer monazite disclosed the following percentage of thorium oxide: [Analystz Wylie (1950, p. 165)] Percent 06203 _____________________________________ 28. 6 118403 _____________________________________ 13. 1 Nd203 _____________________________________ 1 1. 9 Pr203 ______________________________________ 3. 52 8111203 _____________________________________ 3. 0]. Th0; ______________________________________ 5. 93 NEW ZEALAND Detrital monazite is widely distributed in small amounts in unconsolidated and consolidated sediment- ary rocks on South Island and Stewart Island, New Zealand, but it is uncommon on North Island (Hender- son, J ., 1924, p. 14; Morgan, 1927, p. 70; Hutton, 1950, p. 667—670; Davidson, 1953, p. 75). Analyses of two samples of monazite concentrates from New Zealand were given by Hutton (1950, p. 668). One concentrate, A, contained 85 percent of monazite and 15 percent of a mixture of grains of zircon, cassiterite, and ilmenite and had a specific gravity of 5.26. The other concentrate, B, contained monazite plus about 6 percent of a mixture of grains of gahnite, zircon, and intergrown ilmenite-titanhema- tite and had a specific gravity of 5.23. The analyses of the concentrates were recalculated by Hutton to 100 percent of monazite and showed the following per- 98 THE GEOLOGIC OCCURRENCE OF MONAZITE centages of thoruim oxide; the monazite is, therefore, of commercially acceptable tenor: [Analyst F. T. Seelye (in Hutton, 1950, p. 668)] Percent A B Ce203 __________________________________ 22. 95 28. 43 (La, Nd, Pr, Sm)203 _____________________ 28. 28 31. 17 (Gd, Y)203 _____________________________ 4.28 2. 32 ThOZ ___________________________________ 5. 32 5. 47 U303 ___________________________________ 1. 23 . 00 P205 ___________________________________ 27. 12 28. 57 $103 ___________________________________ 2. 46 1. 18 A1203 _________________________________________ 1 1. 03 F6203 __________________________________ 2. 88 2 . 93 (Ta Nb)203 _____________________________ 5. 48 _______ CaO _________________________________________ . 82 MgO _________________________________________ . 08 Total ____________________________ 100. 00 100. 00 Riggs high value for A1203 may result from included sillimanite (Williams, 1934, 2 Fe0+Fe203. A. Ngahere gold dredge, Grey River, South Island, on south flank of Paparoa B. Plaeitiggt Mudtown, Port Pegasus district, Stewart Island. Monazite has not been obtained from placer con- centrates in New Zealand, although recovery was con- sidered in 1946 at some gold dredges on South Island (Chem. Eng. and Mining ReV., 1946, p. 53). In South Island the gold placers worked by the Atarau, Black- ball, Grey River, Ngahere, Red Jacks, and Slab Hut dredges in the drainage basin of the Grey River are monazite bearing (Hutton, 1950, table 19), but mona- zite has not been recovered. Other dredges on South Island that work monazite-bearing gravels but have not recovered monazite are the Barrytown dredge between the mouth of the Grey River and Charleston and the Arahura, Kaniere, Rimu, and Gillespies Beach dredges south of the mouth of the Grey River. No monazite has been produced from the placers on Stewart Island or from the iron sands along the Taranaki coast of North Island. The New Zealand Geological Survey has considered the monazite to be too sparse to be worth the cost of recovery (Hender- son, John, 1924, p. 14). SOUTH ISLAND Early bulletins of the New Zealand Geological Survey mentioned monazite in cassiterite-bearing gold placers along the west coast and in the northwestern part of South Island in the Westland and Nelson Divi— sions. Detrital monazite was said (Ross, Kenneth, 1906, p. 12) to be a doubtful constituent of sluice-box concentrates from the Waimangaroa River and to be present in glaciolittoral deposits south of Whareatea River (Wareatea) where it is associated with rhodon- ite, zircon, and platinum. Detrital monazite was re- ported (Marshall, 1908, p. 109) in small amounts in sand at Greymouth and was seen with cassiterite, gold, and chromite at Montgomery’s Terrace sluicing claim northeast of Greymouth near Blackball where it was reported by Morgan (1911, p. 91) to have come from granitic and gneissic rocks in the Paparoa Range to the north of the placer. A concentrate of unspecified mineral composition from a sluicing claim near Grey- mouth was shown (MacLaurin, 1912, p. 23) to con- tain 0.62 percent of ThOZ and 4.68 percent of REzOg. In the Reefton area northeast of Greymouth between the Paparoa and Victoria Ranges, monazite, zircon, and garnet are in all the streams (Henderson, John, 1917, p. 224). North of Greymouth in the drainage basins of the Buller and Mokihinui Rivers monazite occurs with gold in placers at Bradshaw (New Zea- land Mines Rec., 1903, p. 128; Engineer, 1904; Morgan, 1913, p. 117—118) and Fairdown, and small amounts of monazite were discovered in black sand along the coast (Morgan and Bartrum, 1915, p. 123). A con- centrate from Bradshaw contained 0.2 percent of Th02 and 0.42 percent of RE203 (Fry, 1905, p. 27). Monazite in a concentrate containing garnet, zircon, magnetite, and gold has been reported from Aorere in the Col- lingwood district at the extreme northwest end of South Island (MacLaurin, 1913, p. 24; Morgan and Bartrum, 1913, p. 21). This concentrate contained 0.6 percent of RE203 plus ThOg. A concentrate from the same area, possibly the same concentrate, was chemically analyzed and found to contain rare earths, but the minerals were not described (Ongley and Mac- pherson, 1923, p. 43). Gravel in an unspecified gold- dredging area on the west coast of South Island has recently been estimated to contain 0.0005 percent of monazite which has 4.93 percent of ThOz and 1.15 percent of U308 (Chem. Eng. and Mining Rev., 1946, p. 53). Methods for recovery of the monazite as a byproduct of gold dredging were being investigated in 1946. The distribution of monazite and other heavy min- erals in South Island was the subject of a compre- hensive study by Hutton (1950), and the subject of short reports by F. J. Turner (1943), and by Hutton and Turner (1936). The studies showed that small amounts of detrital monazite are common in most sediments on the Island except near Lake Manapouri and the Waiau Valley in Southland, in most of Otago, and at the Wainui Inlet. Monazite was present in only two out of nine samples of Tertiary sandstone exposed near Lake Manapouri, and in these monazite was a scarce ac- cessory mineral. Monazite was found in concentrates from a coarse sandstone exposed 0.25 mile east of Circle Cove, Lake Manapouri, and in the heavy frac- NEW ZEALAND 99 tion from a coarse sandstone at Freestone Hill near the lake. The probable source of the few grains of monazite in the two samples was the Fiordland com- plex of gneisses and schists (Hutton and Turner, 1936, p. 256—262). Monazite is absent from Teritary sediments in the Waiau Valley in Southland where the sediments have been derived from norites (Hutton and Turner, 1936, p. 262—263). Alluvium eroded from weathered gabbro and ultramafic rocks has been the source of gold at the Round Hill placers along Ourawera Stream in the Longwood district of Southland (Macpherson, 1938, p. 743). Monazite was reported by Macpherson as probably accompanying the ilmenite, magetite, green hornblende, zircon, and garnet with which the gold is associated, but its occurrence is uncertain. A few grains of monazite were discovered by Hutton and Turner (1936, p. 263—265) in one sample of Ter- tiary sandstone from Bob’s Cove, Lake Wakatipu, northwestern Otago. The main monazite-bearing sediments on South Island are alluvial and fluvioglacial deposits in the drainage basin of the Grey River and littoral and stream deposits along the coastal plain from Cape Foulwind to Westport (Hutton, 1950, p. 697). Heavy- mineral concentrates from this region are characterized p by zircon, monazite, xenotime, and cassiterite. Hutton examined numerous specimens of granite, gneiss, and schist from the northwestern part of South Island, including rocks from the Paparoa and Victoria Ranges, for monazite. He found the monazite, how- ever, to be almost wholly restricted to biotite gneisses of middle and upper amphibolite facies. Concentrates from the granites and schists contained no monazite except for rare samples in which one or two grains were observed. The main exposures of monazite—bearing gneiss are along the west coast south of Charleston, at the mouth of the Nile River, and in the upper reaches of the Otututu River (Hutton, 1950, p. 699). Migmatites in the Charleston-Fox River area contain monazite (Hutton, 1950, p. 696). These high—rank metamorphic rocks seem to have been the main source of monazite in sediments of Quaternary, Tertiary, and Triassic to Jurassic age in this part of South Island. Erosion of the gneisses and sediments provided the monazite in the Recent stream and beach sands. Sand from the beach at Charleston was said (Donovan, 1930, p. 25) to contain considerable garnet, smaller amounts of monazite and zircon, and a trace of gold and silver. The distribution of monazite along the coast of South Island southwest of Greymouth, where it has been found in four placer districts and occurs as an accessory mineral in concentrates panned from stream gravels (Hutton, 1950, table 19), seems to be related more to sedimentary recycling of detrital monazite through an involved sequence of geomorphic and glacial events, than to several independent primary sources. Independent sources, Such as the Fiordland gneisses at Lake Manapouri (Hutton and Turner, 1936, p. 256—262), seem to contribute little monazite to the sediments. The sources of the monazite found in small amounts elsewhere on South Island have not been discussed. Monazite-bearing auriferous oassiterite placers are found at the extreme south end of Stewart Island in the Port Pegasus district (Williams, 1934, p. 344— 354). The roof of an extensive granitic batholith which invaded amphibolite, calc—silicate hornfels, biotite-muscovite schist, and quartzite is exposed in the southern part of Stewart Island. In the Port Pegasus district only the granite, schist, and quartzite crop out, and the steeply dipping metamorphic rocks form the crest of a mountainous ridge known as the Tin Range. Cassiterite-wolframite lodes cut the quartzite and biotite-muscovite schist in the Tin Range. Monazite has not been observed in the lodes, nor has it been seen in thin sections of the rocks in the Port Pegasus district, but detrital monazite is common in concentrates from the eluvial and alluvial placers. The grains of detrital monazite ordinarily are slightly abraded euhedral crystals of prismatic habit. Many grains are clouded with what Williams (1934, p. 354) assumed to be thorite dust. Some grains of monazite include interwoven fibers and silky needles of sillimanite, but sillimanite itself is found in few of the concentrates. It occurs as needles in monazite and quartz and as discrete fragments. Wil- liams concluded that the placer monazite was derived from the schists and that it was formed in the schists from fluids that invaded the schists to produce the cassiterite-wolframite lodes. NORTH ISLAND A little monazite has been observed in sediments that underlie some of the detrital black iron sands on the west coast of North Island. Magnetite sands are found along the Taranaki coast of North Island from Patea in the south to New Plymouth in the north, and scattered deposits have been observed as far north as the Manakau Heads near Auckland (Wylie, 1937, p. 227). The largest deposits are at Patea, New Ply- mouth, and Manakau Heads. The principal minerals are magnetite, ilmenite, quartz, augite, hornblende, and diopside. Zircon is scarce. Small traces of cerium oxide have been noted in some analyses of the ores, 100 but the location and mineralogy of the cerium oxide— bearing samples were not given (Wylie, 1937, p. 228). Mineralogical studies of the sand at Patea (Hutton, 1940, p. 193B—198B) and New Plymouth (Hutton, 1945, p. 297—302) disclosed that monazite was present only in the southern part of the Taranaki coast at Patea. Even at Patea the terrace, beach, and dune deposits of titaniferous iron sands do not contain monazite. Rather, two sedimentary units below the iron sands, called the Patea silts and the Hawera series, are monazite bearing. Monazite is a scarce min- eral in the silts and constitutes less than 5 percent of the heavy minerals from the Hawera series. The small number of reported occurrences of mona- zite on North Island may possibly be related to the absence of the monazite-bearing gneisses seen on South Island (Ongley, 1947, map of North Island). The absence of present exposures of these gneisses on North Island, however, is unlikely to be fully re- sponsible for the scarcity of monazite there. Several lines of geologic evidence have been developed to show that gneissic rocks and granites like those in the north— western part of South Island lie submerged off the west coast of North Island or are buried in the center of North Island. Thus, Wellman (1948, p. 1~2) com— mented that bouldery detritus found in Tertiary and Mesozoic conglomerates on North Island and derived from sources now submerged off the west coast of the island seems to have come from the same group of rocks in which the monazite-bearing gneiss of South Island is found. Hutton (1940, p. 204B) wrote that despite the possibility the monazite at Patea may have been derived from the gneisses in the northwestern part of South Island when Cook Strait was closed in Teriary time and streams flowed into what is now the western part of North Island, there is strong evidence that a granitic source may be concealed under graywackes in the center of North Island or sunk off the west coast. Hutton stated (1940, p. 204B) “it is clear that acid intrusives and metamorphic rocks may have at times been exposed in the North Island, and hence the source of many of the minerals in the heavy residues may well have been, perhaps after rewash from previous sediments, a North Island metamorphic and intrusive terrain.” That monazite was not found in sediments on North Island may not reflect as much the absence of gneissic and granitic terrane as it reflects the sparseness of monazite in the plutonic sources in or adjacent to North Island. ANTARCTICA The beach sands of a small island about 110 miles north of Cape Royds and near the volcanic Mount THE GEOLOGIC OCCURRENCE OF MONAZITE Erebus were said to contain detrital monazite (Fitzau, 1909, p. 480; Osterreichische Zeitschrift fur Burgund und Hut-tenwesen, 1909). Seemingly the monazite is not of local origin. Traces of monazite occur be- tween Cape Adare and Gaussberg (Mining and Eng. Rev., 1911, p. 192). Monazite is an accessory mineral in kyanite—biotite gneiss at Garnet Point, Adélie Coast (Mawson, 1940, p. 397). It is an uncommon accessory mineral in cataclastically metamorphosed and recrystallized gran- ite boulders in morainal deposits at Cape Denison, Adélie Coast (Kleeman, 1940, p. 239—241). Monazite is a common minor accessory mineral in boulders of granite gneiss with primary flow banding in the same morainal deposits (Kleeman, 1940, p. 249—250). Other accessory minerals in the granite gneisses are xeno- time, zircon, magnetite, sphene, and allanite. Xeno- time and allanite are each more common than mona~ zite in the granite gneiss fragments from the moraines at Cape Denison. Rocks in the moraines resemble bedrock at Cape Denison. Fragments of pyroxene marble from the moraines at Commonwealth Bay contain possible monazite as an accessory mineral (Glastonbury, 1940, p. 307—308). The marble consists mainly of calcite with some black pyroxene altering to epidote, some forsterite pseudo- morphically replaced by serpentine, and some micro- cline. Minor constituents include scapolite, sphene, graphite, apatite, zircon, magnetite, and possible monazite. The marble formed at very high meta- morphic grade from limestone. NORTH AMERICA The first sources of monazite that were important in world commerce were the fluvial placers in the Piedmont province of North and South Carolina. These deposits were mined from 1887 to 1911 and again from 1915 through 1917. Other exploited sources of monazite in the United States are beach placers in Florida, placers in Idaho, and a fluvial deposit in the Coastal Plain of South Carolina. Large resources of monazite have been discovered in fossil placers in sandstone of Late Cretaceous age in the San Juan Basin of Colorado and New Mexico but have not been exploited. Very large resources of monazite doubtless exist in the sedimentary rocks of the Atlantic and Gulf Coastal plains of the South- eastern United States and along the gulf coast of Mexico. Little or no monazite has been found in Central America or on the islands of the Caribbean Sea. A large deposit of bastnaesite in California, similar rare-earth-bearing deposits in Canada, and thorium-bearing veins in the Western United States NORTH AMERICA and Canada assure sources of rare—earth metals and thorium independent of the presently known supplies of monazite. CUBA Monazite was reported from Finca Parnaso, Victoria de las Tunas, and Finca Magdalena, Caney, in Oriente Province and from Ciego de Avila in Camagiiey Prov- ince, but the mode of occurrence was not described (Roig, 1928, p. 177). DOMINION OF CANADA Canada was deficient in monazite in 1933, and its needs were met by imports (Wilson, A. W. G., 1933, p. 70). Even as late as 1956, no thorium ore was produced, but there were minor resources of the metal (J anes, 1956, p. 14). Rare—earth minerals were thought to be more abundant (Mining Journal, 1925b). Inasmuch as nearly all Canada was glaciated in Pleistocene time, economically important residual or placer deposits of monazite are unlikely to be found (Ellsworth, 1932a, p. 108). A few preglacial gold placers in British Columbia were protected from glaciation, as were parts of Yukon Territory, but no significant placers have been found, although several monazite—bearing concentrates have been reported. Since the retreat of the last glacial ice, insufficient time has elapsed for residual deposits or stream placers to form (Ellsworth, 1932a, p. 109). Fossil placers, many of great antiquity, have proved to be the main source of monazite. BRITISH COLUMBIA Small amounts of monazite in concentrates from gold placers were noted along the North Thompson River in the early 1900’s by Day and Richards (1906b, p. 1220—1221). Molybdenite-uraninite veins at Hazel- ton were said to contain monazite and allanite (Hein- rich, 1958, p. 271). Although monazite was reported from other localities in British Columbia, specific deposits were not cited, and deposits were said to be too small to be minable (James and others, 1950, p. 255; Steacy, 1953, p. 549). Monazite is a sparse accessory mineral in concentrates from the Quesnel River about 8 miles upstream from its confluence with the Fraser River (Lang, 1952, p. 46). Placer deposits on Bugaboo Creek were mentioned as a possible source for thorium, but it is not certain from the reference if the thorium mineral is monazite (J anes, 1956, p. 14). MANITOBA The monazite—bearing pegmatite on the Huron claim in the Winnepeg River area of southeastern Manitoba 101 has frequently been cited because it contains monazite and other scarce minerals, but the monazite is only a minor constituent of the dike (DeLury and Ellsworth, 1931, p. 569—570; Ellsworth, 1932a, p. 164—167; Lane, 1938b, p. 130—131; Lang, 1952, p. 116; Cumming and others, 1955, p. 64). According to DeLury and Ells- worth (1931), the pegmatite on the Huron claim is one of several dikes and sills that occur in plutonic igneous rocks and roof pendants of metavolcanic and metasedimentary rocks in an area extending from Shoal Lake, which is near the Ontario border, as far north as the Grass River. These pegmatites are most abundant in the area extending from the Oiseau and Winnipeg Rivers southward to West Hawk Lake and Falcon Lake; and several pegmatites are known near Island Lake. The pegmatite characteristically contains some or all of a large group of minerals: spodumene, lepidolite, amblygonite, beryl, topaz, cassiterite, molyb- denite, bismuthinite, bismuth, apatite, monazite, columbite, tantalite, and uraninite. Monazite is more abundant than uraninite, and both occur as crystals and grains embedded in feldspar; but the monazite is apparently not very common in these pegmatites. The Huron claim is 0.5 mile inland from the south- east shore of the Winnipeg River about 9—10 miles upstream from Pointe du Bois (DeLury and Ellsworth, 1931, p. 569). This pegmatite is in a roof pendant of andesite schist. Its strike conforms to the eastward strike of the schist which is parallel to the trend of a contact of the schist with granite about 1,500 feet north of the pegmatite. Monazite from the Huron claim was analyzed several times for age determina- tions. Microchemical analysis by Hecht and Kroupa (1936, p. 98) disclosed the following percentage of thorium oxide: Percent Percent RE203 ______________ 46. 28 MgO _______________ 0. 10‘ Th02 _______________ 14. 42 PbO ________________ l. 30 U303 _______________ . 14 MnO _______________ . 71 P205 ________________ 22. 46 Insoluble residue _____ . 50 Si02 ________________ 8. 50 H20~ ______________ . 69 A1203 _______________ . 52 H20+ ______________ 1. 24 F6203 _______________ . 95 CaO ________________ 3. 23 Total _________ 101. 04 An analysis by Muench (1950, p. 131) showed 15.63 percent of Th02 in monazite from the Huron claim. Monazite was said to be present in a large pegmatite dike in the Bird River area of Manitoba (Mining World, 1958). In addition to the monazite, the dike reportedly contains beryl, topaz, columbite, tantalite, and cesium and rubidium minerals. NEWFOUNDLAND Poorly sorted, stratified sand of Pleistocene age that is exposed in a raised delta of a small stream a mile 102 inland from Nain, Labrador, is monazite bearing (Martens, 1929, p. 23). The deltaic sediments were derived from anorthosite, granite, and gneiss. About 9 percent of the sand consists of heavy minerals, which in one sample were as follows: [Analystz Martens (1929, p. 31)] Frequency Frequency percent percent Black opaque minerals- 20 Rutile _______________ Trace Garnet _______________ 7 Biotite _______________ 0. 2 Hornblende ___________ 31 Monazite _____________ . 2 Hypersthene __________ 19 Sillimanite ___________ . 5 Augite _______________ 14 Tourmaline ___________ Trace Epidote ______________ 2 Actinolite ____________ . 2 Sphene _______________ . 2 Apatite ______________ 4 Total __________ 99. 0 Zircon _______________ . 7 NORTHWEST TERRITORIES Fine-grained monazite occurs with uraninite in dolo- mite at the east end of McLean Bay on Stark Lake (Lang, 1952, p. 65). The locality is 16 miles east of Snowdrift in the East Arm area of Great Slave Lake. Two radioactive zones, 6 feet and 10 feet wide respec- tively, are present. They are stained reddish brown by hematite. Average abundances of U308 and Th02 in the most radioactive parts of the zones were said to be about 0.005 and 0.025 percent, respectively. Monazite is a minor constituent in small well-sorted beach placers on the south shore of Yamba Lake (Folinsbee, 1955, p. 7). Magnetite, ilmenite, and almandite are the most abundant heavy minerals. A very large suite of minor minerals is present and includes andalusite, apatite, brookite, epidote, horn- blende, kyanite, olivine, pyroxene, rutile, scheelite, sphene, sillimanite, spine], staurolite, tourmaline, zircon, and monazite. The immediate source of the heavy minerals is esker sand on the south shore of the lake, but the original source was gneiss and migmatite. The migmatite consists of Oligoclase, quartz, and biotite; accessory monazite, rutile, and zircon; local accessory cordierite; and patchily distributed silli- manite, kyanite, graphite, and almandine garnet (Folinsbee, 1955, p. 9—10). Granitelike lenticular masses that are about 1 foot long and 2 inches wide and that are composed of alkalic feldspar, quartz, muscovite, and excessively scarce monazite occur in the migmatite. A biotite-rich phase of the migmatite near Yamba Lake contains 0.01 percent of monazite. The beach placers on the lake are about 50—100 feet long, 3—10 feet wide, and 6 inches thick; thus, the total amount of black sand is small, and monazite makes up only 1 percent of the concentrate. Monazite in the placers has the same crystal habit, size range, and physical properties as the monazite in the migmatite. Its specific gravity is 4.91—4.94 :0.05, and according THE GEOLOGIC OCCURRENCE OF MONAZITE to spectrochemical analysis by G. M. Gordon it con- tains 1.7 percent of Th02 (Folinsbee, 1955, p. 15). The Yamba Lake placer monazite was reported to contain 4.8 percent of Th02 and 0.25 percent of U303 (Gott- fried and others, 1959, p. 21) . Apparently several other monazite placers of uneco- nomic size and tenor are known in the Northwest Terri- tories (James and others, 1950, p. 255), but specific localities have not been published. NOVA SCO'I‘IA. Monazite occurs in a cassiterite-bearing pegmatite dike in light-gray granite on the Reeves farm 3 miles west of New Ross, Lunenburg County (Spence, 1930, p. 491; Ellsworth, 1932a, p. 255—256). The dike is about 8 feet wide and consists of feldspar, quartz, a little mica, and accessory amblygonite, durangite, cassiterite, scheelite, wolframite, lepidolite, monazite, and beryl. Monazite was also found as a minor acces- sory mineral in the granite. A pegmatite at Lake Ramsay in the New Ross area contains monazite and gummite but is not certainly known to be related to cassiterite-bearing pegmatite dikes in the area (Lang, 1952, p. 155) . Monazite is present as an accessory mineral in granite at localities 3.8 miles east of Port Mouton, 0.5 mile east of Albany Cross, and near Shelburne (Hurley and Fairbairn, 1957, p. 942). The monazite from the Port Mouton area contains 4.4 percent of Th02, that from Albany Cross 2.9 percent, and that from Shel- burne 8.6 percent. 0 NTARIO Pegmatite dikes consisting of graphic intergrowths of quartz and microcline and containing muscovite, biotite, garnet, and molybdenite in Dickens Township, Nipissing District, have been the source of museum specimens of monazite since the early 1920’s (Ells- worth, 1924, p. 261—262; 1932a, p. 192—195; 1932b, p. 19; Mining Jour., 1925b; Lang, 1952, p. 142; Cumming and others, 1955, p. 53). At least three dikes in the area are known to be monazite bearing. They are located in lot 27, concession 5; lot 9, concession 13; and lot 19, concession 1. The first of these occurrences was mined for feldspar and mica in 1943, and the last was being worked for feldspar in 1952 (Lang, 1952, p. 142). None is a commercial source of monazite. These pegmatite dikes intrude garnetiferous granite gneiss, biotite schist, hornblende schist, and mafic intrusive rock (Ellsworth, 1932a, p. 192—195). Mona- zite in the pegmatite dike in lot 9, concession 13, occurs as flat crystals that range from reddish brown to black. The monazite, which had a specific gravity of 5.27, was black (Ellsworth, 1932a, p. 264; 1932b, p. 21, 26) NORTH AMERICA because of finely divided carbon disseminated in a normal monazite having the following composition: [Analyst Ellsworth (1932a, p. 264; 19321), p. 21, 26)] Percent Percent 06203 _______________ 22. 63 02:0 ________________ 0. 35 (La, Di) 20,-, __________ 34. 63 MgO _______________ . 02 (Y, Er)203 ___________ 4. 66 PbO ________________ . 33 Th02 _________ . ______ 7. 32 H20 — ______________ . 06 U303 _______________ . 32 H20+ ______________ . 34 P205 ________________ 27. 89 C __________________ Trace SiOg ________________ 1. 54 A1203 _______________ <. 10 Total _________ 100 27 Fe203 _______________ . 08 Ellsworth (1932a, p. 195) reported that several other pegmatite dikes in the Dickens Township area contain monazite, but that they also are mineralogical locali- ties, not commercial sources. Monazite occurs sparingly in a molybdenite-bearing biotite pegmatite at the Cameron property 2 miles east of the south end of Vermilion Lake and about 15 miles north of Kenora (Lang, 1952, p. 118). At another locality about 1.5 miles east of Vermilion Lake and north of Kenora, biotite—rich zones of a pegmatite dike in greenstone contain monazite (Lang, 1952, p. 121). Monazite is a minor accessory mineral in a pegmatite dike in lot 23, concession 15, Lyndoch Township, Ren- frew County (Ellsworth, 1932a, p. 228; Freeman, 1936, p. 30; Lang, 1952, p. 146). The dike, which occurs in gneissic red granite, consists of quartz and coarse- grained microcline that is partly replaced by albite, muscovite, beryl, tourmaline, fluorite, magnetite, zircon, columbite, lyndochite (thorium calcium euxenite), garnet, and monazite. This pegmatite is 20 feet thick and more than 100 feet long. Although the pegmatite was mined for beryl in a small way in 1926, only a few crystals of monazite have been observed in it. The largest crystals were about 2 inches across by 0.5 inch thick. Monazite apparently occurs with euxenite and colum— bite in a pegmatite mined for feldspar in Conger Township a few miles south of Parry Sound (Lang, 1952, p. 141; J anes, 1956, p. 14). A body of pegmatite in Pitt Township was also reported to contain a little monazite (Lang, 1952, p. 150). Sheetlike pyritic uranium deposits in gently dipping quartz-pebble conglomerates and quartzites in the Blind River region contain yellow, orange, brown, green, and amber grains of monazite (Traill, 1954; Stockwell, 1957, p. 109; Davidson, 1959b, p. 1319; Mair and others, 1960, p. 341—343). The quartzites and conglomerates are 1—3 feet thick and are at the base of the Mississagi quartzite of Huronian age that uncon- formably overlies granite and greenstone. The Huronian sedimentary rocks are slightly metamor- phosed and contain argillite and a minor amount of 103 limestone in. addition to the conglomerate and quartz- ite. In the Blind River region the Mississagi quartzite is 1,500—3,500 feet thick. Monazite, uraninite, and brannerite occur in the matrix of the conglomerate as discrete, very fine grained particles. Zircon, rutile, magnetite, anatase, thorogummite, galena, chalcopyrite, pyrrhotite, and cobaltite are present in small amounts. Most of the grains of monazite are round, but a few are crystal fragments. Monazite is highly erratic in distribution in the conglomerate, being fairly common at one place and almost absent elsewhere. Gold is also irregularly distributed. Brannerite and uraninite are the major ore minerals; immense reserves were reported (Stock- well, 1957, p. 109). Sedimentary and hydrothermal hypotheses for the origin have been proposed, but an original detrital origin possibly modified by low—grade dynamothermal metamorphism may best explain the origin and distri- bution of monazite in the deposit. In this area, a study of the composition of the monazite at different places in the deposit would help explain the origin. Clay of Pleistocene age in the Don valley, Toronto, contains a few scarce grains of monazite in a complex suite of heavy detrital grains (Derry, 1933, p. 114, 116). It is not a typical mineral of the clay. The monazite is associated with augite, diopside, dolomite, enstatite, epidote, dominant garnet and hornblende, hypersthene, kyanite, leucoxene, magnetite, ilmenite, sphene, topaz, zircon, and zoisite. One out of three samples of beach sand from the shore of Lake Ontario just east of the entrance to Toronto Harbor contained detrital monazite (Trainer, 1930, p. 194—195). The beach sand formed from mate- rial eroded from cliffs of glacial and interglacial sedi- mentary deposits at Scarborough Heights east of Toronto. A. garnet-rich layer of the beach sand con- tained the monazite; a mineralogical analysis of the heavy-mineral concentrate of this layer follows: [Analystz Trainer (1930, p. 195)] Percent Ilmenite ___________________________________ 3. 9 Garnet ____________________________________ 56. 0 Augite _____________________________________ 4. 8 Pyroxene __________________________________ 4. 8 Leucoxene _________________________________ 1. 6 Hornblende ________________________________ 27. 0 Monazite __________________________________ 1. 6 Total ________________________________ 99. 7 QUEBEC The earliest descriptions of monazite in Quebec were references to masses and crystals in pegmatite at the Villeneuve mica mine in Villeneuve Township, Papi- neau County (Hoffman, 1887; 1889, p. 92; 1890, p. 184; 104 Genth, 1889, p. 203; American Naturalist, 1889; Good- win, 1897, p. 218; Obalski, J., 1906, p. 72). The peg- matite is about 150 feet wide and strikes northeastward parallel to the foliation of the enclosing garnet gneiss. It consists of quartz, microcline, albite, muscovite, black tourmaline, spessartite, and lesser amounts of apatite, fluorite, zircon, beryl, uraninite, monazite, and cerite (Ellsworth, 1932a, p. 240—241; Dresser and Denis, 1949, p. 437; Spence, 1930, p. 431; Lang, 1952, p. 154). Villeneuve mine was opened for muscovite in 1884, and about 1887 a rounded mass of reddish— brown monazite weighing 12.25 pounds was discovered. This mass had a specific gravity of 5.138 (Hoffman, 1887) and was said to have been slightly altered. A specimen of monazite having specific gravity of 5.233 from the Villeneuve mine was analyzed and was found to have the following composition: [Analystt Genth (1889, p. 203; see also I ohnstoneh 1914, p. 58, and Imp. Inst. [London], 914a, p. 60 Percent Percent 06203 ________________ 24. 80 F6203 ________________ 1. 07 (La, D0203 ___________ 26. 41 03.0 _________________ 1. 54 (Y, Er)203 ____________ 4. 76 MgO ________________ . 04 Th0. ________________ 12. 60 H20 _________________ . 78 P205 _________________ 26. 86 —— SiOz _________________ . 91 Total __________ 99. 77 Except for mineralogical samples this mine is not a source of monazite. In the adjoining West Portland Township, monazite has been found as large well-formed tabular crystals as much as 6 inches across in a granitic pegmatite dike that also contains euxenite and allanite (Spence, 1930, p. 431). The dike, which occupies an area about 30 by 75 feet, is emplaced in biotite gneiss. The monazite and euxenite are present in about equal amounts and are associated with abundant black tourmaline in albite—rich zones in the pegmatite (Spence and Muench, 1935, p. 725—728). Most of the monazite is severely weathered, thus, paragenetic relations are obscure, but the possibility exists that some of the monazite was altered to allanite prior to the weathering. Possibly the original alteration was related to metamorphism during the Taconic orogeny (Spence and Muench, 1935, p. 728, 731). Three determinations by Muench (in Spence and Muench, 1935, p. 732) disclosed 3.39, 3.38, and 3.55 percent of Th02 in the monazite, and the fol— lowing complete analysis showed 4.25 percent of Th02 and 0.11 percent of U308, which was determined separately: [Analyst Friedrich Hecht (in Spence and Muench, 1935, p. 732; see also Cumming and others, 1955, p. 56)] Percent Percent RE203 ______________ 62. 09 CaO ________________ 0. 99 Th0; _______________ 4. 25 MgO _______________ . 56 P205 ________________ 27. 39 H20+ ______________ . 60 SiOz ________________ 3. 21 A1303 _______________ . 69 Total _________ 101. 88 Fe205 _______________ 2. 10 THE GEOLOGIC OCCURRENCE OF MONAZITE The dike was mined for feldspar and was reported to have been the source of about 20 pounds of monazite during the middle or late 1930’s (Lang, 1952, p. 154). Pegmatite exposed 6 miles northwest of Lepine Depot north of Maniwaki was said to contain monazite and allanite (Lang, 1952, p. 152, 153). Monazite is a minor accessory mineral in the Am— herst graphite deposits about 12 miles from St. J ovite (Cirkel, 1911, p. 109—115). The area is underlain by gneiss and crystalline limestone of the Grenville Series intruded by pyroxenite, granite, diorite, and diabase. Crystalline graphite is found in veins that consist of about 75 percent of intermixed graphite, orthoclase, perthite, microcline, albite, and anorthite and 25 per- cent of mixtures of augite, hypersthene, wollastonite, calcite, and quartz. Fine-grained apatite, sphene, and garnet are commonly enclosed in the feldspar. Scat— tered grains,.small crystals, or minute scales of scapo- lite, zircon, muscovite, pyrite, leucoxene, biotite, mona- zite, and magnetite occur as sparse inclusions in the feldspar and pyroxene. Inasmuch as the graphite also occurs as clean, perfect crystal inclusions in the feld- spar, Cirkel (1911) inferred that graphitic carbon was present when the veins formed. The veins may be pegmatitic deposits. Monazite from this unusual occur— rence has not been analyzed. Monazite is a minor accessory mineral in a pegrnatite dike exposed at Lac Pied des Monts in De Sales Town~ ship, Charlevoix County, about 18 miles northeast of Murray Bay. (Dresser and Denis, 1949, p. 437—438). The dike is 15—20 feet thick and consists of microcline, albite, quartz, abundant biotite, and some muscovite. Along with the monazite, small quantities of zircon, uraninite, and thucholite are present. Sparse accessory monazite occurs in skarn at the Calumet Uranium Mines, Ltd., holdings in Grand- Calumet Township (Shaw, 1958, p. 30—32). The skarn consists mainly of calcite and contains small amounts of diopside, lithium mica, chondrodite, uranoan tho- rianite, uranothorite, and monazite. A bulk sample of the skarn contained 0.10 percent of U308 and 0.15 percent of Th02. Apparently very little of the tho- rium is in the monazite. Marine sand of Pleistocene age exposed about 275 feet above present sea level on the Ile d’Alma, Lake St. John County, is monazite bearing (Martens, 1929, p. 20). Adjacent areas are underlain by part of the Saguenay anorthosite, but granite, gneiss, and am- phibolite are locally present in the distributive prov- ince from which the sand was derived, and muscovite— rich pegmatite dikes in the Saguenay area have long been known to be monazite bearing (M. J. Obalski, 1904, p. 173). The marine sand on the Ile d’Alma NORTH AMERICA contains about 10 percent of heavy minerals, evenly distributed through it. A concentrate from the sand was described as having the following amount of monazite: [Analystz Martens, 1929 (p. 31)] Fre- Fre- quency quency percent percent Black opaque minerals- 29 Zircon _______________ 3 Garnet _______________ l O Rutile _______________ . 2 Hornblende ___________ 28 Biotite _______________ Trace Hypersthene __________ 14 Monazite _____________ . 2 Augite _______________ 11 Altered feldspar _______ . 5 Epidote ______________ 1 —— Sphene _______________ 1 Total __________ 99. 9 Apatite ______________ 2 Alluvial deposits around East Angus were prospected for black sand and gold in 1939 (Quebec Miner, 1939). Particular attention was said to have been given to possible economic occurrences of garnet, zircon, mona- zite, rutile, and ilmenite; but apparently very little if any monazite was recovered, because detrital monazite is not mentioned in the literature on this area. SASKATCHEWAN A northwest-trending fault zone between amphibo— lite and granite gneiss and pegmatite in the Lake Athabaska district near Uranium City was reported to contain 15 percent of monazite in a vein 12 feet wide (Mining World, 1955). Unconcentrated ore from the vein was reputed to average a little more than 1.0 percent of ThOg. Monazite occurs at a locality near the Fond-du-Lac River about 0.5 mile west of Stony Rapids and east of the east end of Lake Athabaska (Lang, 1952, p. 109). Its abundance and geologic relations are not known. ' In the Beaverlodge area, migmatitic gneiss locally has thin biotite—rich layers which contain as much as 25 percent of monazite (Heinrich, 1958, p. 270). Two concentrates from the Saskatchewan River were reported to contain extremely small amounts of monazite (Day and Richards, 1906b, p. 1220—1221). Both concentrates were black sand tailings from gold placers, but the exact localities were not described. YUKON TERRITORY Discovery of monazite in Yukon Territory was con- sidered possible by Ellsworth in the early 1930’s (1932a, p. 108), but the mineral was not found until the early 1950’s. Monazite occurs in concentrates from Boulder Creek and Clear Creek, which are tributaries to the McQuesten River in the Mayo Dis- trict (Lang, 1952, p. 40) . Its source seems to be local granitic rocks, where it is associated with allanite. 105 GREENLAND Medium- to fine—grained dark nepheline syenite (lujavrite) composing the youngest member of the Ilimaussaq massif in the J ulianehaab District of southwestern Greenland contains accessory monazite, steenstrupine, and several unidentified radioactive minerals (Bondam and Siirensen, 1959, p. 555). Sam- ples of the monazite have low alpha activity of 0—1,900 alpha particles per square centimeter per hour, which suggests that some, and possibly much, of the mona— zite from the nepheline syenite has little or no the- rium. The rock is hydrothermally altered, and the monazite seems to have formed from eudialyte during the hydrothermal activity. In the Kvanefjeld area, syenite and analcime-rich lujavrite contain many monazite-rich pseudomorphs after eudialyte (Bondam and Sérensen, 1959, p. 557). Black sands from the coast were said to contain very sparse monazite (Martens, 1929, p. 31). Very small quantities of monazite occur in sand from the shore of a small lake on the island of Egedesminde south of Godhavn (Martens, 1929, p. 27, 31). The lake occupies part of the glaciated surface of the island and is in granite and granite gneiss. Heavy minerals make up 4 percent of the beach sand, and monazite is only 0.2 percent of the concentrate: [Analystz Martens, 1929 (p. 31)] Percent Percent Black opaque minerals- 0. 5 Apatite ______________ 4 Garnet _______________ 8 Zircon _______________ 2 Hornblende____ - _ _ _ _ _ _ 63 Rutile _______________ 1 Hypersthene __________ 4 Monazite _____________ . 2 Augite _______________ 3 Sillimanite ___________ . 2 Epidote ______________ 1 1 -— Sphene _______________ 2 Total __________ 98. 9 HONDURAS AND BRITISH HONDURAS A trace of monazite was reported by Day and Richards (1906b, p. 1222—1223) in a concentrate con- sisting dominantly of ilmenite, garnet, zircon, and magnetite from Trujillo in Honduras. The geologic source of the concentrate was not described. Monazite occurs in granitic detritus and alluvium near the headwaters of Stamn Creek in British Hon- duras, where it is associated with detrital cassiterite and molybdenite (Thomson, 1952b, p. 319). The source of the detritus is a granite which intrudes sedimentary rocks of late Carboniferous age. At the contact the granite locally contains cassiterite. MEXICO Monazite is present as a minor accessory mineral in the La Grulla granodiorite in the Sierra San Pedro de Martir, Baja California (Jafi'e and others, 1959, 106 p. 82). Alpha activity recorded for the monazite suggests that it may have about 4 percent of Th02. The possible presence of monazite placers in the beach sands along the coasts of the State of Oaxaca was suggested by Gonzalez Reyna (1956, p. 323), but none had been reported as of 1960. UNITED STATES OF AMERICA Fluviatile monazite placers in the Piedmont prov- ince of North and South Carolina were a commercial source for monazite from 1887 to 1911 and 1915 through 1917 (table 30). During the later part of this same period a little monazite was also taken from valley placers in Idaho. In the late 1940’s the placers in Idaho were reopened, and a monazite-bearing stream in the extreme western part of the Coastal Plain of South Carolina was dredged. Some ilmenite placers in Florida have a small byproduct output of monazite, as do lode mines for molybdenum in Colo- rado and spodumene in North Carolina. Large fossil placers of monazite have been found in the Western States and Michigan, but they have not been mined. The dependence of the United States on monazite as a source for the rare earths and thorium has been greatly lessened by the discovery of very large deposits of bastnaesite in California and thorite in the Rocky Mountains. ALABAMA The older reports on the mineral resources of Ala- bama did not discuss monazite, although at the time the reports were published, active mining of, or ex— ploration for, monazite had been or was under way in North Carolina, South Carolina, and Florida (Smith and McCalley, 1904; Jones, W. B., 1926). Monazite was not reported from the mica pegmatites of Alabama (Heinrich and Olson, 1953, p. 408). In 1951, Mertie (1953) discovered monazite in Alabama, and by 1955, Pallister (1955, p. 33, 45, 47, 54) and Broadhurst (1955, p. 79) were referring to its occur— rence in crystalline rocks and in streams in Chilton, Coosa, and Tallapoosa Counties and in crystalline rocks in east-central Alabama. Monazite is an un- common mineral in these rocks and apparently is too sparse to be detected in most places by car-borne counters; thus, Stow (1955a, p. 18—19, 28) did not mention monazite in his description of the radioactive outcrops in Alabama, although he observed an area of anomalously high radioactivity to the southwest of Rockford that may relate to the monazite occurrences in Coosa County discovered in 1951 by Mertie (1953, p. 23). THE GEOLOGIC OCCURRENCE OF MONAZITE The most thorough descriptions of monazite in Ala- bama were given by Mertie (1953, p. 15, 23, 26). He found that the Pinckneyville Granite is sparsely mona- zite bearing at 11. places in Coosa and Tallapoosa Counties, and he found small amounts of accessory monazite in granitic gneiss at 6 localities in Chambers County. These 17 mineralogical occurrences together form the southwest end of a belt of monazite-bearing crystalline rocks traced by Mertie (1953, pl. 1) 600 miles northeastward across the western part of the Piedmont province of Georgia, South Carolina, North Carolina, and Virginia. The southwest end of the belt is covered by the overlapping sediments of the Coastal Plain in Alabama. None of the occurrences in Ala- bama is a commercial source for monazite. Streams in the area that is underlain by monazite- bearing granites and gneisses no doubt have small amounts of detrital monazite, as reported by Pallister ( 1955, p. 33), but no placers have been mined. Inas- much as fluviatile placers having more favorable source areas in North Carolina were thought to be uneconomic sources for monazite (Overstreet, Theo- bald, and Whitlow, 1959, p. 714), it is not likely that economic stream placers exist in the less favorable source areas of the Piedmont province of Alabama. Monazite occurs as accessory detrital grains in parts of the Coastal Plain sediments in Alabama and on the islands and beaches of the gulf coast west of the ilmenite placers near Panama City, Fla. Sedimentary rock in the Tuscaloosa Formation of Cretaceous age at the inner edge of the Coastal Plain was found by Dryden (1958, pl. 22) to contain mona- zite at 17 out of 18 localities sampled from Phenix City to the Coosa River north of Prattville. The tenor of the monazite-bearing samples, as estimated by Dryden, was between 0.01 and 0.25 pound of mona- zite per cubic yard. Samples from other parts of the Coastal Plain in Alabama disclosed similar low abun— dances of monazite. At three localities from Troy to 20 miles north, the sedimentary rocks contained from 0.01 to 0.15 pound of monazite per cubic yard. A sam- ple from Troy contained no monazite, and three samples from more than 20 miles south of Troy con- tained from 0.05 to 0.16 pound per cubic yard. ALASKA Monazite in Alaska was first described by Mertie (1925, p. 263) in a discussion of gold placers at Chandalar. It was again noted by Waters (1934, p. 239) in heavy minerals accompanying cassiterite in the Tofty area. As monazite is not an abundant mineral in Alaska, its distribution was not well known ALABAMA AND ALASKA 107 TABLE 30.——Monazite, in short tons, produced in N orth Carolina, South Carolina, Idaho, and Florida from 1880 to 1960 Year Source references North South Idaho Florida United States Carolina Carolina total 1880 ___________________________ 1 ____________________________ 0. 015 ______________________________ 0. 015 1881—6 ________________________ 2, 3 __________________________ (1) ______________________________ 1) 1887 ___________________________ 4, 5 __________________________ 12 ______________________________ 12 1888—92 _______________________ 5 ____________________________ (4) ______________________________ (2) 1893 ___________________________ 65 ______________________________ 65 1894 ___________________________ 273 ______________________________ 273 1895 ___________________________ 787 ______________________________ 787 1896 ___________________________ 2, 3, 6—8, 16 __________________ 15 ______________________________ 15 1897 ___________________________ 22 ______________________________ 22 1898 ___________________________ 125 ______________________________ 125 1899 ___________________________ 175 ______________________________ 175 1900 ___________________________ 2, 3, 6—9, 16 __________________ 454 ______________________________ 454 1901 ___________________________ 2, 3, 6—8, 16 __________________ 374 ______________________________ 374 1902 ___________________________ 2, 3, 6—8, 16 __________________ 401 ______________________________ 401 1903 ___________________________ 2, 6—8, 16 _____________________ 387 44 ____________________ 431 1904 ___________________________ 2, 6—8, 16 _____________________ 343 29 ____________________ 372 1905 ___________________________ 2, 7, 8, 10, 16 _________________ 447 225 ____________________ 672 1906 ___________________________ 2, 7, 8, 11—13, 16 ______________ 349 74 2—3 __________ 423 1907 ___________________________ 2, 7, 14, ___________________ 228 46 (4) __________ 274 1908 ___________________________ 2, 14-16 ______________________ 155 56 (4) __________ 211 1909 ___________________________ 2, 14—16 ______________________ 196 75 (4) __________ 271 1910 ___________________________ 2, 3, 14—16 ____________________ 42 8 (4) __________ 50 1911 ___________________________ 15, 16 ________________________ (4) ______________________________ (4) 1912 ___________________________ 15, 16 ________________________ (4) ______________________________ (4) 1913—14 ___________________________________________________________________________ 1915 ___________________________ 3, 16 _________________________ 18 ______________________________ 18 1916 ___________________________ 19 ______________________________ 19 1917 ___________________________ 3, 13, 16 ______________________ 39 ____________________ 11 50 19 18 ______________________________________________________________________________ 1919 ___________________________ 3, 16 ________________________________________________________________ (5) 1920-24 ___________________________________________________________________________ 1925 ________________________________________________________ 1 1 1926—38 ________________________ 16 _______________________________________________________________________________ 1939—45 ________________________ 17 _______________________________________________________________________________ 1946—48 ________________________ 18, 19 ____________________________________________ 0 40 __________ 40 1949 ___________________________ 20 _______________________________________________ (7) (4) (9) 1950 ___________________________ 21 _______________________________________________ (9) (9) (9) 1951 ___________________________ 22—25 ____________________________________________ (4 10) (4) (9) 1952 ___________________________ 26 _______________________________________________ (9) (9) (9) 1953 ___________________________ 27, 28 ________________________ (‘1) __________ (9 ul) (9) (9) 1954 ___________________________ 9 _____________________________________ (14) (4 l4) (9) (9) 1955 ___________________________ 24, 3O __________________________________ (15) (° 1°) (17) 0‘) 1956 ___________________________ 31 _____________________________________ (15) (18) (47) (7) 1957 ___________________________ 32 _____________________________________ (15) (13) (15) (7) 1958 ___________________________ 33 _____________________________________ (19) (2°) (3) (7) 1959 ___________________________ 34, 35 ____________________________________________ (21) (22) 23 1, 143 1960 ____________________________________________________________________________________ (3) (7) l A few tons mined in 1886 but none shipped. 4. Pratt (1903, p. 183). 3 A few tons produced per year, but record not kept. 5. Pratt (1902, p. 61). 3 Not marketed. 6. Pratt (1905, p. 45-46). 4 Small production, not marketed. 7. Pratt (1908 p. 66). 5 One producer, figures not released, point of origin not specified in references. 8. Pratt (190711, p. 123). 0 Recovered from Boise Basin area, Boise County. 9. Pratt (1901, p. 30). 7 Output not reported. 10. Pratt (1907a, p. 41). 5 Very small production as a byproduct of ilmenite mining. 11. Franklin Inst. Jonr. (1908, p. 318). 9 Production classified. 12. Fleck (1909, p. 205). 10 Production commenced at Big Creek, Valley County, Idaho; three dredges in 13. Sloan (1908, p. 14). operation by end of year. 14. Pratt and Berry (1919, p. 104—105). 11 One producer, output not released, probably small. 15. Pratt (1914, p. 81). 12 Three dredges in operation at Big Creek. 16. Houk (1946, . 11-12). ‘3 Dredge under construction on Horse Creek, Aiken County, 8.0. 17. Matthews (1848, . 1208). 14 Two dredges in operation at Big Creek; construction commenced on dredge at 18. Clark (1950, p. 1&2). BearValley. 19. Kline, Carlson, and Griffith (1950, p. 24). 15 One producer, output not released. 20. Clark (1951,1111. 1249 . 1° Oumut at Big Creek ceased in August 1955; preparations to mine continuing at 21. Lamb, Nort , and Chandler (1953, p. 1354—1355). BearV ey. 22. Keiser (1954, p. 1302). 17 Two producers, output not given. 23. Lamb (1955a . 4). ‘8 Monazite recovered beginning in June 1956 as a byproduct of mining euxenite 24. Eilersten and Eamb (1956, p. 25). placer in Bear Valley, production figures not released. 25. Kline and Carlson (1954, p. 13). 1’ Greatly reduced production, figures not released. 26. Keiser (1955, p. 1089). 40 Greatly reduced roduction at Bear Valley, a little monazite shipped from Boise 27. Councill (1955, p. 6). Basin, figures not re eased. 28. Crawford (1956, p. 1212). 21 B gproduct monazite from stockpile built in 1958 dredging at euxenite placer in 29. Crawford (1958a, p. 1157-1158). Bear alley and from ilmenlte stockpile in Bo1se Basin. 30. Crawford (1958b, p. 1125). '4 Three producers, outp’ut not given. . 31. Crawford (1958c, p. 1156—1157). *8 Combined monazlte, astnaesite, thorite, and thonum—rare earths residue. 32. Paone (1958, p. 1146—1147). 33. Paone (1959, p. 1037—1038). Sources: 1. Genth and Kerr (1881, p. 84). 2. Pratt (1916, p. 52—53). 3. Santmyers (1930, p. 15). . Lewis (1960, p. 895). . Paone (1960, p. 1070). . Parker (1961, p. 927). 108 until the late 1940’s and early 1950’s when the US. Geological Survey searched for occurrences of radio- active minerals. Between 1945 and 1952 the Survey staff examined several thousand heavy-mineral con- centrates from mining districts throughout the State and conducted ground and airborne radiometric re- connaissance at many selected localities. Less than 48 occurrences of monazite were discovered, and even in these occurrences monazite is generally exceedingly scarce. Two reasons seem to account for the sparseness of the known monazite—bearing areas in Alaska. One is the possible failure of radiometric surveys to detect monazite in areas masked by heavy vegetation. Un- doubtedly monazite has been missed by both ground and airborne radiometric surveys, but at most locali- ties where it has been found in Alaska, monazite is present in such small amounts that the discovery itself indicates a high sensitivity of the radiometric methods. The second, and main, reason for the sparseness of monazite seems to be a geologic environment that is generally unfavorable for its development. Monazite in Alaska is ordinarily found as detrital grains in stream sediments, but at several localities detrital monazite occurs in littoral sediments. The detrital monazite was derived from granitic rocks in which it is a minor accessory mineral. The monazite- bearing granitic rocks are massive and are emplaced in almost unmetamorphosed to moderately metamor- phosed sedimentary rocks; such rocks are not usually rich in monazite. The chief host rocks of monazite, which, elsewhere in the world, are profoundly plutonic rocks, such as sillimanite gneisses, granulites, and migmatites, have not been discovered in Alaska. Ab- sence of these rock types accounts for the sparseness of detrital monazite. Monazite-bearing carbonate-hematite veins have been found in southeastern Alaska. The monazite- bearing veins are radioactive, but the amount of tho— rium in the monazite is not known. In many respects these veins resemble those associated with carbonatite deposits elsewhere in the world, and carbonatites con- tain thorium-poor monazite. The monazite-bearing localities are distributed as follows: 4 in southeastern Alaska, 7 in south—central Alaska, 13 in east—central Alaska, 5 in northeastern Alaska, 6 in central Alaska, 3 in southwestern Alaska, and 4 in west-central Alaska. SOUTHEASTERN ALASKA A minor amount of a mineral that was doubtfully identified as monazite was found by West and Benson (1955, p. 37) in a pyrrhotite-rich concentrate from a THE GEOLOGIC OCCURRENCE OF MONAZITE molybdenite-gold-quartz vein and its granitic wallrock exposed in the underground workings of the Mountain View gold mine in the Hyder district. In addition to pyrrhotite and monazite, the concentrate contained large amounts of rutile, molybdenite, and pyrite, and small amounts of chlorite, prehnite, apatite, amphibole, carbonate minerals, and an unidentified brownish- black isotropic mineral. The vein fills a fissure in a granitic dike that cuts across sedimentary and vol— canic rocks of the Hazelton Group of J urassic( ?) age and also cuts the intrusive Texas Creek Granodiorite of Cretaceous or Jurassic age. The monazite may have come from either the vein or the dike. Neither the greenstone, tufi', volcanic breccia, graywacke, slate, argillite, and sparse limestone of the Hazelton Group nor the Texas Creek Granodiorite are known to have monazite. Many narrow mesothermal carbonate-hematite fis- sure veins are exposed along the shore at Salmon Bay on the northeast coast of Prince of Wales Island. Houston and associates (Houston and others, 1958, p. 6—22; Houston and others, 1953; White and others, 1952, p. 16) reported that the veins, which are locally monazite bearing, cut well-indurated graywacke of Silurian age which overlies limestone. The sedimen- tary rocks at Salmon Bay are intruded by many lam— prophyre dikes, some olivine basalt dikes, and a few phonolite dikes; coarse-grained igneous rocks are absent. Three varieties of veins are described, but only the most common one is radioactive and contains mona- zite. This type of vein ranges in width from a frac- tion of an inch to several feet, and averages 2.5 inches. These three varieties of veins fill fissures in graywacke and are composed mainly of a grayish-white carbonate mineral of the dolomite-ankerite series (Houston and others, 1958, p. 10—11). Alkalic feldspar, red hema- tite, specularite, and pyrite are common, and locally siderite and magnetite are abundant. Small amounts of quartz, chalcedony, chlorite, calcite, parisite, bast— naesite, muscovite, fluorite, apatite, thorite, zircon, monazite, epidote, topaz, garnet, chalcopyrite, and marcasite are present. Monazite is very scarce and occurs in only a few veins. Traces of monazite occur in three (table 31) out of six heavy-mineral concentrates from alluvium in the Goddard Hot Springs area of Baranof Island (West and Benson, 1955, p. 4749). The monazite-bearing concentrates come from streams that drain areas un- derlain by granite, altered sandstone, conglomerate, graywacke, and slate. The granite is intruded by narrow dikes of spessartite lamprophyre. ALASKA Near Juneau some weakly radioactive sand was dredged during construction at the airport in 1953 (Holdsworth, 1955, p. 56). Possibly some of the radioactivity was emitted by monazite. TABLE 31.—M1Ineralogical composition, in percent, of monaeite- bearing concentrates from streams in the Goddard Hot Sprmgs area, Baranof Island, Alaska [Modified from West and Benson (1955, p. 49)] 3305 3302 3312 Allanite ________________________ 6 Trace 7 Apatite ________________________ Trace 0 0 Augite __________________ _ 3 Trace 3 Biotite ________________ _ 0 0 1 Chlorite _______________ _ Trace 0 1 *Clinozoisite _____________________ 1 0 Trace Diopside _______________________ 2 1 2 1 Epidote ________________________ Trace Trace 2 Garnet _________________________ 14 23 15 Hornblende _____________________ 6 5 10 H ypersthene ____________________ Trace Trace 5 Ilmenite ________________________ 55 55 44 Limonite _______________________ 0 Trace Trace Magnetite ______________________ Trace Trace Marcasite ______________________ 2 0 0 Monazite __________ _ _ _ _ Trace Trace Trace Pyrite ___________ _ _ _ _ Rutile ___________ _ _ _ _ Trace Trace 0 Scheelite _______________________ Trace Trace Sphene _________________________ 2 0 1 Zircon _________________________ 7 3 5 Total ____________________ 98 98 99 3305. Stream formed by the hot springs. 3302. Stream 1 mile northeast of Goddard. 3312. Stream draining lake north of the hot springs. SOUTH-CENTRAL ALASKA The seven monazite occurrences in south-central Alaska are associated with gold placers. Six of these occurrences were briefly noted by Bates and \Vedow (1953, p. 8—9), and the seventh, monazite in the Cache Creek—upper Peters Creek area of the Yentna district, was discussed by Robinson, Wedow, and Lyons (1955, p. 5—7, 20—21). According to Bates and Wedow, mona- zite was observed in prospectors’ samples from the Mount Spurr area, in concentrates from gold placers at Roundbend Bar, Red Hill Bar, and Shalon Bar on the Kahiltna River and from gold placers in the Petersville area and in Poorman Creek. The Cache Creek—upper Peters Creek area of the Yentna district is underlain by tightly folded, weakly metamorphosed slate and graywacke interbedded with some quartzite and conglomerate (Robinson and others, 1955, p. 5—7); these rocks are unconformably overlain by pebble gravel that is slightly deformed, gravel that is cemented, arkose, clay, and lignite; these units are wholly or in part of Eocene age. Glacial-outwash gravel, possibly late Tertiary in age, overlies the Eocene sediments, and is mantled by glaciofluvial gravel of Quaternary age. The present streams have cut through the Quaternary gravel and 109 have formed as many as seven bench levels below the top of the Quaternary glacial deposits. Stream gravel commonly veneers the benches, the youngest gravel being in the flood plains and channels of the present streams. Concentrates from the different gravel deposits con— tain about the same kinds of heavy minerals, but in variable proportions. Sand and gravel of Eocene age yield concentrates low in sulfide minerals and lacking in tourmaline and apatite. Concentrates from the late Tertiary gravel are rich in pyrite, and those from the gravel of Quaternary age are rich in andalusite and cassiterite. ' Compared with the other gravels, concentrates from the present flood-plain gravels con- tain more apatite, tourmaline, monazite, allanite(?), and iddingsite( '4). Common minerals in all the con- centrates are zircon, hornblende, hypersthene, augite, epidote, garnet, pyrite, ilmenite, chromite, cassiterite, and magnetite. Scarce or variably present minerals and native elements include gold, tourmaline, anda- lusite, biotite, chlorite, iron oxide minerals, a11anite( ‘9), arsenopyrite, copper, stibnite( ?), apatite, sphene, iddingsite, prehnite, rutile( '2) , marcasite, galena, plati- num, and monazite. The origin of the monazite in the sediments is not discussed. Monazite is too sparse in the concentrates for the area to be of economic importance. EAST-CENTRAL ALASKA In east—central Alaska, 5 of the 13 occurrences of monazite were merely mentioned by Bates and Wedow (1953, p. 9—10). These are monazite associated with gold in stream placers at Atwater Bar on the Mos- quito Fork of the South Fork of the Fortymile River, Copper Creek, Coal Creek, and Woodchopper Creek and monazite in granitic bedrock and fluvial gold placers in the Slate Creek area. Ober Creek near Donnelly contains placer gold to- gether with small quantities of detrital monazite, tourmaline, zircon, fluorite, and epidote (Wedow and others, 1954, p. 18). The drainage basin of Ober Creek is underlain by schists and gneisses of Precam- brian(?) age, but the source of the monazite is not known. Placer concentrates from a gold dredge on Nome Creek in the Chatanika area contain sparse monazite and tourmaline and abundant cassiterite. The source of the monazite is unknown (Wedow and others, 1954, p. 8—9), but it may come from a granite stock at the head of Nome Creek. The stock is of Mesozoic”) age and intrudes quartz-mica schist, quartzite, and some augen gneiss and crystalline limestone of the Birch Creek Schist. 110 Placer concentrates from the Livengood area, par- ticularly from Ruth Creek, contain a few grains of monazite (Bates and Wedow, 1953, p. 10; Wedow and others, 1954, p. 11). Granitic rock of possible Mesozoic( ?) age intruded into schist and exposed on Excelsior Creek in the Eagle-Nation area contains a few grains of monazite (Wedow, 1954, p. 6—9). Of 38 concentrates from the granite, only 1 contained monazite. Sediments of Tertiary age composed of granitic detritus and prob- ably resting directly on granitic bedrock are exposed along Mission Creek and American Creek in the Eagle-Nation area. Suites of heavy minerals from these sediments contain ilmenite, iron oxide minerals, zircon, small amounts of garnet and anatase, and traces of epidote, hornblende, hypersthene, rutile, bio- tite, apatite, and monazite. No economic monazite placers are known in the area. Out of 13 heavy-mineral concentrates from the Miller House—Circle Hot Springs area (Nelson and others, 1954, p. 11—15), 3 contain monazite (table 32). TABLE 32.—Mineralog1.'cal composition, in percent, of monazite- bearing concentrates from the Miller House-Circle Hot Spnngs area, Alaska [Compiled from Nelson and others (1954, table 8). Symbol used: -_, absent] 4718 4677 4679 Allanite ________________________ _ _ _ - Trace Apatite ________________________ _ _ Trace _ _ Arsenopyrite ____________________ _ _ Trace 1 Biotite _________________________ 24 10 Trace Bismuthinite ____________________ _ _ - _ Trace Cassiterite ______________________ _ _ _ _ Chalcopyrite ____________________ _ _ Trace _ _ Chlorite ________________________ _ _ Trace Diopside _______________________ _ _ _ _ Fluorite ________________________ _ _ 1 _ _ Garnet _________________________ 1 1 10 Gold ___________________________ _ - _ _ Trace Hematite _______________________ _ _ 2 5 Ilmenite ________________________ 10 6O 50 J amesonite _____________________ _ _ Trace _ _ Limonite____________-_‘ _________ __ Trace __ Magnetite ______________________ _ _ _ _ 15 Malachite ______________________ Trace _ _ _ _ Monazite _______________________ 10 4 Trace Muscovite ______________________ _ _ _ _ Trace Pyrite __________________________ _ _ 1 1 Pyrochlore-microlite _____________ _ _ _ _ Trace Pyrrhotite ______________________ 35 _ _ _ _ Scheelite _______________________ Trace Trace 1 Sphalerite ______________________ _ - 1 _ _ Sphene _________________________ _ _ _ _ 1 Spine] __________________________ _ _ _ _ 1 Topaz __________________________ 5 _ _ Trace Tourmaline _____________________ _ _ _ _ Uranothorianite _________________ _ _ _ _ Trace Wolframite _____________________ _ _ _ _ 5 Zircon _________________________ 1 5 10 1 Total ____________________ 100 97 98 4718. Granite exposed in Bedrock Creek near Miller House. 4677. Granite bedrock underlying H. C. Carsten's gold placer on Portage Creek near Circle Hot Springs. 4679. Sluice-box concentrate from gold placer in same locality as 4677. THE GEOLOGIC OCCURRENCE OF MONAZITE One concentrate is from granite of Mesozoic( ?) age; the second concentrate, from granite bedrock under- lying a gold placer; and the third is from the placer. The two concentrates from granite are unusually rich in monazite for rock in Alaska. NORTHEASTERN ALASKA Ten placer concentrates were collected from the Wiseman gold area by White (1952, p. 8—11), but only 1, a sample from Rye Creek, contains monazite. Even for that sample the following composition shows that monazite is less than 1 percent of the concentrate: Percent Percent Ilmenite _____________ 35 Gold _________________ Trace Schist fragments ______ 25 Scheelite _____________ Trace Chlorite ______________ 2 0 Sphene _______________ Trace Andalusite ___________ 7 Kyanite ______________ Trace Zoisite _______________ 5 Zircon _______________ Trace Epidote _____________ 5 Monazite _____________ Trace Pyrite _______________ 3 Chalcopyrite __________ Trace Total __________ 1 00 Galena _______________ Trace Monazite found in the Chandalar gold district in concentrates from placers from Big Creek was the first reported occurrence in Alaska. In the same dis- trict, concentrates from placers yield trace amounts of monazite at Tobin Creek, a few grains at Little Squaw Creek, a few grains together with zircon and uranothorianite at the middle fork of Big Squaw Creek, and some from Gold Bench on the South Fork of the Koyukuk River (Mertie, 1925, p. 263; White, 1952, p. 8—12; Nelson, 1953; Nelson and others, 1954, p. 16—19). Concentrates from Gold Bench, a deposit of high-level stream gravel 200—300 feet above the river, consist of magnetite, garnet, hematite, zircon, olivine, epidote, sphene, pyrite, scheelite, galena, chal- copyrite, rutile, Cinnabar, cassiterite, bismuthinite( ?), thorianite( ?), and monazite. Monazite occurs only in trace amounts in the concentrates. The Chandalar area is underlain by mica and chlorite schists cut by dikes of greenstone and granite gneiss. Although Mertie (1925, p. 263) suggested that the geologic source of the monazite might be some highly silicic granitic rock, possibly pegmatite, later investigations have not verified this. The survey by Nelson, West, and Matzko (1954, p. 16) did show, however, that finding commercial quantities of monazite in stream gravel in the Chandalar district is unlikely. CENTRAL ALASKA Quartz monazite at Elephant Mountain contains monazite, and the nearby stream deposits at Eureka are monazite bearing (Moxham, 1954a, p. 6). The quartz monzonite intrudes slate, quartzite, and schist. ALASKA The Tofty tin deposits in the Manley Hot Springs— Rampart district were first observed to contain mona- zite by Waters (1934, p. 239—242) . These tin deposits consist of a belt of placers in gravel of late Tertiary or early Quaternary age buried under 15—80 feet of frozen silt of Pleistocene age. Cassiterite and gold are mined, and some chromite is found at the west end of the belt. Several possible sources for the placer cassiterite have been suggested (Waters, 1934, p. 242— 246; Moxham, 1954a, p. 6), but tin lodes have not been found. The monazite described by Waters occurred in part as fine-grained pebble-forming aggregates. He men- tioned (Waters, 1934, p. 239) a very well rounded fine-grained light-buff pebble of monazite measuring 0.75 inch in its greatest dimension from the north side of Deep Creek and well-rounded light-buff very fine grained pebbles of monazite measuring 1 inch in their greatest dimension from Sullivan Creek just north of the old site of Tofty. At Deep Creek the placer monazite is accompanied by cassiterite, pyrite, ilmen- ite, picotite, magnetite, zircon, quartz, and eschynite. The monazite from Sullivan Creek is accompanied by the same minerals plus xenotime, orthoclase, plagio— clase, gold, copper, apatite, epidote, brookite, and anatase. Monazite was absent from all five samples taken by Waters from streams north of the Tofty tin belt. Out of 14 samples from these streams, 9 contain monazite. One out of two samples from streams south of the belt is monazite bearing. Thus, the dominant mona- zite-bearing stream deposits are within the tin belt. Monazite from the Tofty tin placers is weakly radio- active. Moxham (1954a, p. 5) reported that the equivalent uranium content of the monazite does not exceed 1 percent. This low content suggests that the abundance of Th02 in the monazite does not exceed 4 percent. Low abundances of thorium oxide are characteristic of monazite from many tin deposits. Monazite-bearing granite of Tertiary age forms a stock in slate, quartzite, and schist of Cretaceous age between Hot Springs Dome and Manley Hot Springs. Most of the streambeds in the area underlain by the granite contain monazite, but those in the metasedi- mentary rocks seemingly lack monazite. Indirect evidence from radiometric traverses indicates that monazite is uncommon, possibly virtually absent, in the aureole of metasedimentary rocks around the stock (Moxham, 1954a, p. 4). Monazite is found in gold placers in gravel of Ter- tiary age exposed on Boulder Creek in the Manley Hot Springs—Rampart district. The monazite may 111 have come from a stock of quartz monzonite which crops out nearby at Roughtop Mountain (Moxham, 1954a, p. 6). SOUTHWESTERN ALASKA The Nixon Fork gold district is underlain by lime- stone of Paleozoic age, and sandstone, shale, and slate of Late Cretaceous age (White and Stevens, 1953, p. 10—12). This sedimentary sequence is cut by quartz monzonite thought to be Eocene in age. Contact- metamorphic zones between the limestone and the quartz monzonite are rich in garnet and are the site of lodes containing oxidized copper-gold ore and bismuth minerals. Also present in the contact zone are a variety of radioactive minerals including sphene, allanite, vesuvianite, zircon, uraniferous thorianite, and parisite (a rare-earth fluocarbonate). More than 100 heavy-mineral concentrates were prepared by White and Stevens (1953, p. 16) from stream deposits and rock units in the district, but only 1 concentrate, which was from a gold placer, contained monazite. The radioactivity of the monazite was not discussed. Julian Creek, an east—flowing tributary to the upper Middle Fork of the George River 25 miles southeast of Flat, drains an area underlain by sandstone and slate cut by a few narrow dikes of porphyritic granite, all of which are presumed to be Late Cretaceous in age (White and Killeen, 1953, p. 16—18). A concen— trate from a sluice box at the Harry Steen gold mine on Julian Creek contained 10 percent of rock-forming minerals, 80 percent of pyrite, and 5 percent each of garnet and monazite. The monazite is thorium bear- ing, but the amount of thorium is not known. Questionably identified monazite occurs in minor amounts in two out of three concentrates from sluice boxes at a gold placer on Candle Creek (White and Killeen, 1953, p. 16—18). Candle Creek enters the Tatalina River 5 miles southwest of McGrath. Gold has been dredged from placers 4 miles downstream from the head of the creek just below a contact between a small quartz monzonite, exposed in the upper reaches of the stream, and sandstone and shale of Cretaceous age in the lower course of the stream. Some of the placer gold apparently comes from quartz veins associ- ated with the quartz monzonite. The two monazite- bearing concentrates consist of about 5 percent of rock- forming minerals, 90 percent of spinel, 3 percent of zircon, and 2 percent of a mixture of Cinnabar, scheelite, and monazite( ?). The source of the monazite was not specified. WEST-CENTRAL ALASKA Monazite was found by West (1953, p. 2, 4, 7) in one concentrate from the east shore of Golovnin Bay 112 between Cape Darby and Portage Creek on the Seward Peninsula. Beach sand in the area is derived from an igneous complex of pre-Cretaceous age which makes up the Darby Mountains. The complex is composed mainly of gneissic granite which has been metamor- phosed to various degrees. Some diorite and green- stone are included in the complex. Even—grained t0 porphyritic granite, also said to be pre-Cretaceous in age, intrudes the complex. Which members of the complex contribute the monazite to the beach sand are not known. A monazite-bearing stock of granite forms the cen- tral part of Ear Mountain on the Seward Peninsula. Killeen and Ordway (1955, p. 65—68) stated that the stock is 2 miles in diameter and that it intrudes shale, slate, quartzite, and limestone. They thought the lime- stone to be of Ordovician age, but the ages of the other rocks are uncertain. Altered gabbro intrudes the sedi- mentary rocks, and several dark-gray mafic dikes con- taining large phenocrysts of biotite cut the granite stock. The stock has apophyses of alaskite, and a variety of veins cut rock in the area. Lime-silicate rocks at the contact between the granite and limestone consist of garnet, hedenbergite, vesuvianite, scapolite, axinite, and tourmaline and minor amounts of horn- blende, datolite, magnetite, and pyrite. Monazite is such a common accessory mineral in the granite stock that it can be seen in thin section (Killeen and Ordway, 1955, p. 86). Minerals having high thorium to uranium ratios, such as monazite, occur as accessories in the granite, but they were not observed in the veins. Minerals having high uranium to thorium ratios were found in the veins. This distri- bution suggested to Killeen and Ordway that the thorium was largely concentrated in the early formed accessory minerals of the granite and that the uranium was concentrated in the final products of crystallization. Concentrates were collected by Killeen and Ordway (1955, p. 76—83) from 100 localities in streams rising in the area underlain by the granite and flowing out onto the area underlain by sedimentary rocks. The total volume of monazite in concentrates from individ- ual riflles was very small, but monazite was found in every concentrate. Killeen and Ordway estimated that the riflie gravels contained from 0.7 to 32 pounds of concentrate per cubic yard, the heaviest concentrates being obtained downstream from the contact between the granite and limestone. Monazite, cassiterite, and zircon constituted most of the concentrate from streams in the area underlain by the granite. Downstream from the granite these minerals are accompanied by variable, locally large, amounts of garnet, vesuvianite, axinite, diopside, hypersthene, biotite, tremolite, apa- THE GEOLOGIC OCCURRENCE OF MONAZITE tite, schee-lite, fluorite, topaz, magnetite, olivine, epidote, danburite, scapolite, limonite, hematite, and stokesite. The placers at Ear Mountain are not a com- mercial source for monazite (Killeen and Ordway, 1955, p. 91). Brooks Mountain on Seward Peninsula is composed of granite of Mesozoic( ?) age intruded into black slate of Precambrian or Cambrian age and into the Port Clarence Limestone of Ordovician, Silurian, and Devonian age (White and others, 1952, p. 2—6; West and White, 1952, p. 2). The granite is porphyritic and coarse grained and has a medium-grained equigranular border phase. It consists of orthoclase, plagioclase, biotite, smoky quartz, and black tourmaline, and acces- sory monazite, zircon, xenotime, anatase, magnetite, and ilmenite. The radioactivity of the granite was said to be emitted by zircon, monazite, and xenotime, but it is low (West and White, 1952, p. 3—7). The composi- tion of the monazite is not known. Cape Mountain on Seward Peninsula is a nearly circular stock of granite intruded into limestone. Cassiterite lodes and placers have been found in both the granite and the limestone along the northeast margin of the stock. Some distant placers indicate that cassiterite lodes are also in the limestone away from the contact. Monazite, xenotime, and zircon are in placer concentrates from parts of the area near Cape Moun- tain; thus, the source of the monazite is probably the granite or the lodes (Bates and Wedow, 1953, p. 6). The composition of concentrates from drill holes in the area was described by Mulligan and Thorne (1959, p. 38, 48, 62, 66) . They showed that radioactive miner- als are absent from cassiterite-bearing concentrates from 209 churn-drill holes and 10 test shafts on Cape Creek and are present in 71 out of 83 samples from holes on Boulder Creek. The composition of monazite- bearing concentrates from Boulder Creek is given in table 33. The valley of Cape Creek is underlain by limestone and some layers of schist (Steidtmann and Cathcart, 1922, p. 97), and the valley of Boulder Creek heads in granite on the northeast flank of Cape Mountain and flows northward across the contact between the granite and limestone (Steidtmann and Cathcart, 1922, p. 97; Mulligan and Thorne, 1959, p. 48—49) . The mineralogi— cal evidence from the churn—drill holes shows that the monazite comes from the granite stock at Cape Mountain. ARIZONA Monazite was first recognized in Arizona in 1905 by Day (1905a, p. 9), who identified it in black sand from a placer in Yavapai County. Further descriptions by Day and Richards (1906b, p. 1180—1181) identified the ARIZONA AND ARKANSAS TABLE 33.—Mineralogical composition, in percent, of monazite- bearing cassiterite concentrates from churn-drill line .94 in Boulder Creek valley in area underlain by limestone about 0.25 mile downstream from granite, Seward Peninsula, Alaska [Mulligan and Theme (1959, p. 48). Symbol used:._, absent] Chum-drill hole 24 26 28 32 34 36 38 gassiterlte _____________ 40 35 40 50 45 70 20 a cite.... . ._ 5 .. .. Dolomite. . l 35 35 _ _ - . l 10 i 2 1 Quartz..-. 20 25 40 25 25 1 20 45 Augite____ 3 .. _. .. .. __ ._ Diopslde.- .......... __ 2 10 312 3 5 __ 415 Clay ________________ . _ . _ 3 5 4 5 Shale ..... . ._ __ 10 .. ._ _. ._ _ FeldspaL- . _ . _ . . 1 5 5 8 . . 10 Epldote..- 1 _ . . . . . Tr. _ Biotite.... ... 1 1 { Tr. l 1 5 2 Garnet ....... Tr. _ . Tr 1 1 Tourmaline _____ 1 Tr. Tr. 1 1 Chlorlte ........ Tr. _ _ . , _ _ Homblende _____ . . 1 _ _ Tr. Hematite ....... 1 _ _ Staurolite _______ .. __ ._ __ __ Tr. __ Scheelite ........ Tr. Tr. Tr. Tr. Tr. Tr. Tr. Zircon___. __ Tr. __ __ Tr. _. _. Monazite ....... Tr Tr. _ . Tr. Tr. Tr. Tr. Xenotime ....... . _ . . . _ _ _ _ _ Tr. Tr. Tr. Tr. Apatite ................ _. _. ._ ._ __ ._ Tr. 4 Includes auglte and epidote. 5 Includes blotlte. 0 Includes chlorlte. 1 Includes feldspar. 5 Includes garnet and epldote. a Includes epldote. locality as Black Canyon Creek and showed that the concentrate consisted mainly of magnetite and hema- tite, with some garnet and gold but only a trace of monazite. Detrital monazite was discovered by A. E. Knowland in stream gravel in the Chemehuevis mining district about 20 miles southeast of Topock in Mohave County (Heineman, 1930, p. 536; Wilson, E. D., 1939, p. 49; Galbraith, 1947, p. 55; Anthony, 1948, p. 15; Moore, R. T., 1953, p. 26). It is sparingly scattered through the gravel in an area of about 2 square miles. The grains of monazite range from small particles to pebbles 0.5 inch across, and they are euhedral to sub- rounded. Even the most rounded grains retain vestigial crystal faces. Yellow-brown, red—brown, and dark-brown monazite is most common. The specific gravity of the monazite is 5.04. Analyses have not been reported, and the source, which presumably is nearby, has not been found. A long, narrow vein in a granite dike in the Aquarius Mountains, Mohave County, contains quartz, chev- kinite, sphene, monazite, apatite, and cronstedtite (Kauf'fman and Jafle, 1946, p. 582, 587). Cracks in anhedral chevkinite are healed with aggregates of euhedral apatite and sphene, small subhedral to large euhedral grains of monazite, large uniformly oriented flakes of cronstedtite, and a small amount of strained quartz. Granite augen gneiss in Mohave County con— tains accessory monazite (see section on “Clark County, Nevada”). At several localities in northern Arizona, radioactive fossil placers were said to be present in sandstone of 113 Late Cretaceous age, but the exact sites were not speci- fied (Chenoweth, 1957, p. 217). Similar deposits are very common in the San Juan Basin of Colorado and New Mexico. ARKAN’SA S Fine-grained earthy monazite occurs in an apatite- pyrite vein in carbonatite on East Tufa Hill at Magnet Cove, Hot Spring County (Rose and others, 1958, p. 995; Fryklund and Holbrook, 1950, p. 38—39). Monazite was interpreted by Rose and associates to have formed by the weathering of the apatite and is not considered to be an original mineral in the vein. The evidence for this interpretation is not compelling, but the material with which Rose and associates worked was thoroughly weathered. The monazite resembles monazite from other carbonatite bodies and low- temperature veins in carbonate rocks in that it is devoid of thorium. Ilmenite—bearing layers of crossbedded, friable sand and clay near the top of the Tokio Formation of Late Cretaceous age contain sparse monazite in the vicinity of Mineral Springs, Howard County, Arkansas (Hol- brook, 1948, p. 5—9; DeMent and Dake, 1948, p. 11). The area of exposed fossil placers covers at least 6 square miles on the northwest side of the town of Mineral Springs. In their richest parts the placers were said to contain from 1.4 to 12.8 percent of T102, but the amount of monazite was reported to be too small to mine alone. A possible byproduct of monazite output might be obtained if the deposits were worked for ilmenite. The Williana gravel, a pre-Wisconsin deposit of Quaternary age in the lower Mississippi Valley, is locally monazite bearing. A concentrate made from Williana gravel exposed just north of Jonesboro, Craighead County, Ark, contained a little, possibly as much as several percent, of monazite (Fisk, 1951, p. 342): Percent Percent Epidote ______________ 2 Tourmaline ___________ 16 Amphibole ___________ 2 Other minerals (fluorite, Zircon _______________ 36 monazite, corundum, Sphene _______________ 5 undetermined miner- Rutile _______________ 13 als) ________________ 7 Staurolite ____________ 14 Andalusite ___________ 2 Total __________ 100 Kyanite ______________ 3 Monazite is present in but rarely makes up more than 1 percent of the heavy-mineral suite from the present sand of the Mississippi River (Russell, 1937, p. 1330) . In a study of 144 samples of heavy minerals taken from sand in the Mississippi River at localities between Cairo, Illinois, and Profit Island, Louisiana, including samples from Blytheville, Mississippi County, Arkansas, and Helena, Phillips County, Ar- 114 kansas, Russell (1937, p. 1316—1347) observed that no decrease in the relative abundance of monazite took place downstream, although such decrease might be expected owing to the brittleness and softness of mona- . zite. Instead of a decrease, the relative abundance of monazite, and also of zircon, sphene, and rutile, in- creased slightly downstream. This apparent increase in abundance was attributed to the small sizes of these minerals and to a progressive sorting on the basis of size, the small-sized grains becoming more abundant in concentrates from sand in the downstream reaches of the river. Russell also observed in this important study that the persistent detrital minerals are those most resistant to chemical destruction; their relative resistance to mechanical disintegration was of little consequence in their survival during transport (Rus— sell, 1937, p. 1347). Monazite was present in 3 out of 4 concentrates from Mississippi River sand taken in the vicinity of Blythe- ville, and it was present in 10 out of 10 concentrates from the Helena area, Arkansas. In no sample did it attain an abundance as great as 1 percent of the concentrate. CALIFORNIA Monazite has been observed in the black sands of stream and beach placers in California since the early 1900’s and, since the 1930’s, has been found in a few crystalline rocks in the State, but no commercial deposits of monazite are known (Day, 1905a, p. 9; California Div. Mines Staff, 1945, p. 520; Oakeshott, 1950, p. 136). One of the world’s largest known con- centrations of the rare earths, however, is found in the bastnaesite deposits in the Mountain Pass district, San Bernardino County, Calif. (Olson and others, 1954, p. 33—38; Eng. and Mining Jour., 1952a; Murdoch and Webb, 1956, p. 223; Walker and others, 1956, p. 5, 7; Jarrard, 1957, p. 43; Jafl'e, 1955, p. 1247—1249). cnxsmumn ROCKS The geology of the bastnaesite deposits at Mountain Pass, San Bernardino County, has been described in detail by, Olson, Shawe, Pray, and Sharp (1954, p. 4— 62), and the relations and composition of the monazite in them have been summarized by J affe (1955, p. 1247— 1255). According to these writers the Mountain Pass district is in an area of Precambrian garnetiferous mica gneiss and schist, biotite-garnet-sillimanite gneiss, amphibolite, granitic gneiss, and pegmatite. Intrusive into these rocks, and apparently also of Precambrian age, is a suite of potassium-rich igneous rocks consist- ing of shonkinite, syenite, and granite; these rocks form small stocks and thin dikes. In and near the southwest THE GEOLOGIC OCCURRENCE OF MONAZITE side of a large composite stock of shonkinite and syenite are veins and an elongate mass of rare—earth- bearing carbonate rock. Almost 60 percent of the carbonate rock is composed of mixtures of calcite, dolomite, ankerite, and siderite. The remainder of the rock is barite, bastnaesite, parisite, quartz, and variable but minor amounts of crocidolite, biotite, phlogopite, chlorite, muscovite, apatite, hematite, goethite, fluorite, monazite, galena, allanite, cerite, sphene, pyrite, chal- copyrite, tetrahedrite, malachite, azurite, strontianite, cerussite, wulfenite, aragonite, and thorite. The car- bonate bodies are interpreted by Olson and associates as probably originating as the end product of the magmatic differentiation of the alkaline magma from which the shonkinite, syenite, and granite were formed. The monazite occurs mainly in dolomitic masses of carbonate rock, and thorite occurs principally in the veins. The monazite is in small subhedral to euhedral grains that are brown, reddish brown, or yellowish brown. They have from 1 t0 3 percent of Th02 (Olson and others, 1954, p. 38). Analysis of monazite, having a specific gravity of 4.98, from medium- to coarse-grained barite-carbonate rock composed of calcite, barite, bastnaesite, parisite, phlog- opite, monazite, galena, pyrite, quartz, and hematite showed the following percentage of thorium oxide: [Analystsz A. M. Sherwood and H. J. Rose, Jr. (in Jaffe, 1955, p. 1250)] Percent Percent Cegoa _______________ 36. 19 U308 ________________ 1 0. 002 143.203 _______________ 19. 65 P205 ________________ 29. 23 Nd203 _______________ 8. 20 SiOz ________________ . 70 PI‘gOg _______________ 2. 94: szoa ______________ . 85 Total _________ 100. 77 Th0; _______________ 3. ()1 1 U=0.002 percent determined flourimetrically by Frank Cuttitta. Another sample of monazite from the same carbonate mass was estimated to contain 1.54 percent of Th02 on the assumption that all the alpha activity of the mineral was from thorium (Jafl'e, 1955, p. 1254). A specimen of monazite from fine— to medium-grained carbonate rock containing dolomite as the dominant carbonate mineral was analysed by A. M. Sherwood and Frank Cuttitta, US Geological Survey, and found to contain 2.92 per- cent of T1102 and 0.002 percent of U303 (Jaffe, 1955, p. 1253). The composition of a precipitate of the total rare earths and thorium oxide from a specimen of monazite from the Mountain Pass bastnaesite deposits has been reported by Murata, Rose, and Carron (1953, p. 294). In the original specimen the total rare earths plus thorium oxide equaled 72.71 percent of the weight of the monazite (H. J. Rose, Jr., oral commun., 1958). The CALIFORNIA published analysis is recalculated below to total 72.71 percent for comparison with the other analyses: Percent , 1134203 _____________________________________ 19. 93 CeOz ______________________________________ 38. 51 PI‘GOH ______________________________________ 3. 08 Nd203 ______________________________________ 8. 32 Sm203 ______________________________________ . 86 Gd203 ______________________________________ (1) Yzoa ——————————————————————————————————————— (2) Th02 _______________________________________ 2. 01 Total ________________________________ 72. 7 1 l < 0.3 percent in precipitate. 2 < 0.1 percent in precipitate. Monazite was reported as questionably present in porphyritic quartz monzonite and in metasomatically altered inclusions in the Rock Corral area of San Bernardino County (Walker and others, 1956, p. 23— :24; Moxham and others, 1955, p. 111—116). The oc- currences are about 53 miles east-northeast of San Bernardino in an area underlain by biotite gneiss, siliceous metasedimentary rocks, and dark metavol- canic rocks of Precambrian age. Porphyritic quartz monzonite of pre-Cretaceous age intrudes the meta- morphic rocks and contains many inclusions and roof pendants of them. Allanite, zircon, sphene, and mona- zite( ?) are conspicuous accessory minerals in the biotitic wallrocks, in biotitic inclusions, and in biotite- rich parts of the quartz monzonite adjacent to inclu- sions. Allanite is the main thorium-bearing mineral in the Rock Corral area. Isolated inclusions contain as much as 7 percent of allanite. A vein of allanite and monazite about 5—6 inches Wide and 15 feet long is in biotite gneiss at the Black Dog claim 3—4 miles south of Rock Corral (Walker and others, 1956, p. 7, 23—24). Relative abundance of the two minerals has not been reported, but analyses of vein material showing 29.63 percent of RE203, 0.61 percent of Th02, and 0.28 percent of U308 sug- gests that the vein contains scant monazite or that the monazite is especially lean in thorium oxide. The granitic rocks exposed about 4 miles east-north- east of Amboy, San Bernardino County, were said to contain accessory monazite(?) (Walker and others, 1956, p. 26). Pegmatite at the Pomona Tile Co. quarry on the road between Old Woman Spring and Yucca Valley, San Bernardino County, contains a little monazite, allanite, euxenite, and samarskite associated with biotite and ilmenite (Walker and others, 1956, p. 24; Murdoch and Webb, 1956, p. 223). The monazite is most common along the borders of the quartz core of the pegmatite. An analysis of the rare-earth plus thorium oxide precipitate from a sample of monazite 115 from a pegmatite at Yucca Valley, San Bernardino County, was reported by Murata, Rose, Carron, and Glass (1957, p. 148). The published analysis has been recalculated to total 60.46 percent, the original abundance of the precipitate (H. J. Rose, Jr., oral commun, 1958), and it shows a very large amount of thorium oxide: Percent Lagos _____________________________________ 7. 49 CeOz ______________________________________ 17. 96 PraOu _____________________________________ 1. 95 NdzOs _____________________________________ 6. 88 Sm203 _____________________________________ 1. 34 Gd203 _____________________________________ . 79 Y203 ______________________________________ 1. 76 ThOz ______________________________________ 22. 29 Total ________________________________ 60. 46 At the Lucky Seven claim in San Bernardino County accessory allanite and monazite occur in biotitic pods in biotitic granite (Walker and others, 1956, p. 24). Fractures in the granite are coated with allanite( ?) and monazite( ?). Near Copper Mountain, San Bernardino County, at the Homestretch group of claims, biotite-rich parts of a locally gneissic light—tan to pinkish—tan granite contain possible monazite. At the Steiner claims pos- sible monazite and allanite occur along a fault in biotite schist (Walker and others, 1956, p. 24—25). Radioactive minerals in biotite-rich parts of layers of quartz—biotite schist associated with granite gneiss and diorite southwest of the Pinto Basin, San Ber- nardino County, are thought to be allanite and mona- zite, but positive identification has not been made (Walker and others, 1956, p. 25). Slightly altered anhedral crystals of monazite are associated with anhedral and euhedral grains of thorite disseminated in masses of hematite in a peg- matite dike in the S010 district about 12 miles south- southeast of Baker, San Bernardino County (\Valker and others, 1956, p. 22). The dike consists principally of feldspar and quartz. It is only 6 inches to 3 feet wide, and the wallrocks are foliated granite. ' Monazite was reported as a minor accessory mineral in granitic rocks and gneisses in Riverside County (Gary, 1942, p. 106). It occurs in typical quartz diotrite of the Cretaceous batholith in southern Cali- fornia (Larsen and others, 1952, p. 1046), as small euhedral crystals in tonalite exposed south of Val Verde (Wilson, R. W., 1937, p. 124, 126; Murdoch and Webb, 1956, p. 234) and in quartz diorite near the coast south of San Francisco (Hutton, 1952, p. 95). Fine-grained granite at Mt. Rubidoux near Riverside contains accessory monazite, zircon, sphene, and alla- nite, but coarse-grained granite at the same locality 116 lacks monazite, although it has accessory allanite, apatite, sphene, and zircon (Larsen and Keevil, 1947, p. 491; Murdoch and Webb, 1956, p. 233; Smith and others, 1957, p. 369). Precambrian biotite gneiss is possibly monazite bearing in the vicinity of Twenty- nine Palms (Davis and others, 1959). Quartz mon- zonite in the Live Oak Tank area about 12 miles south of Twentynine Palms seems to contain monazite as does biotite gneiss at a locality about 2 miles north- west of Cactus City (Walker and others, 1956, p. 25—26). Pegmatite dikes in Riverside County have frequent- ly been reported to contain accessory monazite, and locally the monazite may make up as much as 0.8 percent of the pegmatite, but none of the dikes is a commercial source of the mineral (Dykes, 1933). A pegmatite dike at the William Niendorfi ranch about 2 miles north of Winchester was the source of museum specimens of monazite and xenotime on crystals of black tourmaline (Symons, 1936, p. 116; Pabst, 1938, p. 205; Chesterman, 1950, p. 362; Murdoch and Webb, 1956, p. 223; Walker and others, 1956, p. 37). Mona— zite was reported from a pegmatite exposed in a magnesite mine near Winchester (Murdoch and Webb, 1956, p. 234). Rosettes of monazite associated with rose quartz have been reported from the Williamson silica mine (Murdoch and Webb, 1948, p. 216; 1956, p. 223). The Southern Pacific silica quarry is in a pegmatite dike in granite about 3 miles east of Nuevo and 15 miles southeast of Riverside. The dike consists mainly of quartz with small amounts of albite and orthoclase and accessory tourmaline, xenotime, and reddish-brown euhedral crystals of monazite as much as 2 inches across (Melhase, 1936; Schwartz, 1944; Chesterman, 1950, p. 362; Murdoch and Webb, 1956, p. 223; Walker and others, 1956, p. 37). Crystals of monazite were reported to have been found with albite in a pegmatite dike exposed about 600 feet west of the Jensen limestone quarry in the Jurupa Moun- tains (Pabst, 1938, p. 205; Chesterman, 1950, p. 362), but Murdoch and Webb (1956, p. 223) thought that the reported monazite may actually have been sphene, which is abundant at the locality. Monazite was said to occur in pegmatite dikes just east of Riverside, at the foot of Box Springs Mountain (Pabst, 1938, p. 205; Murdoch and Webb, 1956, p. 233) and at Moun— tain View (Murdoch and Webb, 1956, p. 234). The VVoodson Mountain granodiorite exposed north- east of Descanso Junction, San Diego County, has accessory monazite (Jafl’e and others, 1959, p. 86). Monazite is also known as an accessory in the lithium- THE GEOLOGIC OCCURRENCE OF MONAZITE bearing Stewart pegmatite (Jahns, 1953, p. 1090), in the ABC mine at Ramona and in the Katerina mine, Hiriart Mountain, Pala (Murdoch and Webb, 1956, p. 234). Sporadic well-formed crystals of monazite are included in garnet in pegmatite at Mesa Grande (Murdoch and Webb, 1948, p. 216; 1956, p. 234; Chesterman, 1950, p. 362). Quartz monzonite exposed near Bishop, Inyo County, has accessory monazite (Jafl'e and others, 1959, p. 89). Granite exposed in the Pacific Grove and Monterey areas, Monterey County, contains abundant accessory monazite (Hutton, 1952, p. 96; Messner, 1955, p. 138). SANDSTONE The sandstones of the California oil fields have been said to contain some 17 varieties of heavy accessory minerals or groups of minerals among which monazite is 11th in order of abundance, being preceeded by the amphiboles, pyroxenes, opaque metallic minerals, epi- dote, micas, garnet group, zircon, tourmaline, apatite, and rutile, and followed by kyanite, brookite, and— alusite, topaz, corundum, and staurolite (Tickell, 1924, p. 166). Monazite was found to be of scare and sporadic occurrence in sandstones of Miocene and Pliocene age in the Kettleman Hills (Bramlette, 1934, p. 1576). Massive sandstone and conglomerate and interbedded soft sand and clay of the Sespe Formation contains sparse detrital monazite (Gianella, 1928, p. 747—748). STREAM nnrosrrs Monazite in some gold placers in California has been knoWn since the early 1900’s when Day and Richards investigated the mineralogical composition of black sands from placer mines along the Pacific slope of the United States (Day, 1905a, p. 5—15; 1905b, p. 19; 1907, p. 144; Day and Richards, 1906a, p. 152; 1906b, p. 1182—1191). The number of occurrences of monazite in stream sediments was scarcely increased by the investigations of radioactive deposits in the 1950’s. By 1956 monazite had been observed in stream deposits at scattered localities from Imperial County in the south to Plumas County in the north, but placer monazite has not been produced commercially (Gary, 1942, p. 106). Monazite was said to occur in placers in the Ogilby district, Imperial County (Walker and others, 1956, p. 37). It is found in sediments of the San Joaquin River near Friant, Fresno County, the Merced River in Merced County, and the Tuolumne River near La Grange and the Stanislaus River in Stanislaus County (Wright, 1950, p. 3; Walker and others, 1956, p. 37). CALIFORNIA Thorium- and cerium-bearing ore, possibly monazite, was reported to have been found at a gold mine on Indian Creek near Sheep Ranch about 14 miles north of Angels Camp, Calaveras County (Miner, 1929); however, the mineralogy was not discussed. At Placer— ville and in the Indian Diggings, El Dorado County, the black sands from gold placers contain a trace of monazite (Day and Richards, 1906b, p. 1184—1185; Pabst, 1938, p. 205; California Mining Jour., 1946). Traces of monazite have been observed in placers at Loomis and at Michigan Bluff, Placer County (Day and Richards, 1906b, p. 1186-1187). Black sands con- taining 4 pounds of monazite, 632 pounds of chromite, and 844 pounds of ilmenite per short ton were found at Rough and Ready in Nevada County (Day and Richards, 1906b, p. 1186—1187). In Yuba County traces of monazite occur in concentrates from placers at Marysville and the Brownsville district (Day, 1905a, p. 19; Day and Richards, 1906a, p. 152; 1906b, p. 1190— 1191; Gary, 1942, p. 106; California Mining J0ur., 1946; Wright, 1950, p. 3). Traces of monazite were reported in magnetite-rich concentrates from gold plac- ers at Little Rock Creek in Butte County (Day and ‘ Richards, 1906b, p. 1182—1183; Pabst, 1938, p. 205; Murdoch and Webb, 1948, p. 216). Concentrates from a gold placer at an unspecified locality in Plumas County were said by Day and Richards (1906b, p. 1186—1187) to contain 10 pounds of monazite, 1456 pounds of magnetite, and 376 pounds of ilmenite per short ton. A later report identified the Plumas County locality as Nelson Point (Pabst, 1938, p. 205). In the early 1950’s the US. Bureau of Mines investi- gated monazite in streams in Yuba, Stanislaus, and Sacramento Counties, and in the beach sands in Mon- terey County. The results of these studies have not been published, but they were summarized by Eilertsen and Lamb (1956, p. 11—13). Only small amounts of black sand, principally magnetite, were found in the fluvial placers. The magnetite was accompanied by sparse to very sparse garnet, zircon, and epidote, and by trace amounts of monazite and uranothorite. Beach sands at the Monterey Peninsula were also found to contain only trace amounts of monazite. The reports on monazite in stream placers in Cali- fornia are largely restricted to the pioneering work of Day and Richards on the accessory minerals in the black sands of gold placers. No independent regional search for fluviatile monazite placers has been made. Direct evidence to support the widely held contention that fluviatile monazite deposits of any size are lacking in California is most inadequate, because no real search 117 has been made for them, and the results of the studies by Day and Richards have been generally accepted. It is common, however, for gold deposits to be found in areas lean in or devoid of monazite. Until a study of streams draining areas underlain by plutonic rocks of high metamorphic grade has been made, the pres- ence of fluviatile monazite placers in California cannot be said to be disproved. Indirect evidence seems to support the idea that monazite is in general sparse in the rocks in California. It is very uncommon in the sandstones in the oil fields, and it is not especially abundant on the beaches. BEACH marosrrs Monazite occurs in beach deposits along the Pacific coast of California. at. Del Norte and Humboldt Coun- ties in the extreme northern part of the State and in San Mateo, Santa Cruz, and Monterey Counties in the central part of the State. It is fine grained and vari- able in its occurrence but was regarded by Day (1907, p. 144) as possibly easier to recover and more abundant than that in the placers in North and South Carolina. By 1918, however, the economic value of the Pacific coast placers was overshadowed by the discovery of large and easily exploitable deposits in India, and the California placers had come to be regarded as having no commercial use (Hornor, 1918, p. 35—37). It is likely that this opinion is still justified, particularly in View of the low tenor in ThOz, 3.5—4.4 percent, reported for monazite from beach placers south of San Fran- cisco. Black sand from Crescent City in Del Norte County was found by Day and Richards (1906a, p. 152; 1906b, p. 1184—1185) to contain 56 pounds of monazite per short ton of concentrate: Tenor (lb. per short ton) Magnetite _________________________________ 48 1 Chromite; _________________________________ 209 Garnet ____________________________________ 503 Olivine ____________________________________ 574 Monazite __________________________________ 56 Zircon _____________________________________ 44 Quartz ____________________________________ 133 Total ________________________________ 2, 000 Sand from Gilbert Creek north of the Smith River, Del Norte County, contained only 0.12 pound of mona- zite per short ton and was also lean in magnetite, chromite, garnet, olivine, and zircon (Day and Richards, 1906a, p. 152). At Trinidad in Humboldt County a 118 trace of monazite was observed in black sand (Day and Richards, 1906b, p. 1184—1185). Beach sands from localities along the Pacific coast between Princeton Beach, San Mateo County, and Pa- cific Grove, Monterey County, were studied by Hutton (1952, p. 8—55; 1953, p. 6—19). He found the natural concentrations of beach sands were very common along this part of the coast but that the zones of concentra- tion were generally short, thin, and impermanent. Lo- cal concentrations of a more permanent character were observed in the backshore zones of beaches at or near the south side of headlands that could interrupt the southward drift of the ocean current. Concentrations were also observed at the south side of the mouths of streams. Relatively stable monazite-bearing deposits of black sand occur at Princeton Beach, the mouth of the Tunitas River, south of Pigeon Point Lighthouse, and just east of Point Afio Nuevo, San Mateo County. In Santa Cruz County they occur on the south side of the mouth of Afio Nuevo Creek and at the mouth of the Pajaro River. In Monterey County, monazite- bearing relatively permanent deposits were reported by Hutton (1952, p. 9) to occur at Marina Beach and Pacific Grove. Dune deposits containing large deposits of monazite— bearing black sand were formed in the vicinity of the mouth of the Pajaro River at the boundary between Santa Cruz and Monterey Counties (Hutton, 1952, p. 11). The mineralogical composition of the beach and dune sands is very complex. Hutton (1952, p. 12a) listed about 50 minerals and varieties of minerals in the full group of concentrates. Most samples contained about 30 different minerals, of which augite, chromite, clin- ozoisite, epidote, garnet, hornblende, hypersthene, opaque grains, rutile, sphene, and zircon are the most common. Relative abundances of the minerals were given according to the scale of Evans, Hayman, and Majeed (1934, p. 41). Recalculation from this scale shows that monazite makes up from 1 to 6 percent of the heavy minerals in the less than 250 mesh and less than 115 but greater than 250 mesh fractions of the concentrate and 1/2 to 1 percent of the less than 60 but greater than 115 mesh and less than 32 but greater than 60 mesh fractions. Monazite from the beach sands forms flat subhedral grains generally devoid of inclusions (Hutton, 1952, p. 49—50). Two separates of monazite from black sand south of the mouth of Afio Nuevo Creek, Santa Cruz County, and from dune sand at Pacific Grove, Monterey County, were chemically analyzed and found to be very similar in composition and to have only 3.49 and THE GEOLOGIC OCCURRENCE OF MONAZITE 3.9 percent of Th02 and a specific gravity at 22°C of 5.21 i 0.02 (Hutton, 1952, p. 51) : [Analystsz A, Atomic Energy Comm.; B, Hutton (1952)] Percent A B Ce203 (group) ___________________________ 64. 8 63. 9 Y203 (group) ____________________________ . 5—1. 0 1. 1 Th02 ___________________________________ 3. 49 3. 9 U308 ___________________________________ . 25 . 2 P205 ___________________________________ 27. 77 28. 2 8102 ____________________________________ . 81 . 9 A1203 _________________________________________ . 15. F()2()3 ___________________________________ . 11 . 2 TiOz ___________________________________ . 04 . O4 (IaO ___________________________________ . 47 . 7 Mg() __________________________________________ . 1 Pb-... ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 018 <. 01 Cu ________________________________________ . 007 1 . 09 MnO _________________________________________ Trace HzO—u ,. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, . 15 Hzo+ __________________________________ i ‘35 { 0m Total _____________________________ 98. 715 99. 6-4 1 CuO. A. Del Monte Properties, Pacific Grove, Monterey County. B. South of the mouth of A50 Nuevo Creek, Santa Cruz County. The rare-earth plus thorium oxide precipitate from the monazite from Pacific Grove was analyzed spectro- chemically and the results, recalculated to 62.3 percent of RE203 plus Th02 in the monazite (H. J. Rose, Jr., oral commun., 1958) show 4.4 percent of T1102 in the monazite: [Analystsz Murata, Rose, and Carton (1953, p. 294)] Percent 113.203 _____________________________________ 13. 6 0602 ______________________________________ 26. 6 PrfiOu _____________________________________ 2. 8 Nd203 _____________________________________ 10. 7 8111203 _____________________________________ 1. 7 Gd203 _____________________________________ . 6 Y203 ______________________________________ 1. 9 Th0; ______________________________________ 4. 4 Total ________________________________ 62. 3 COLORADO Monazite in Colorado apparently was first noted in the early 1900’s in placer concentrates (Day, 1905a, p. 9; Day and Richards, 1906b, p. 1190—1193) , although allanite had been widely observed in crystalline rocks in the State by 1885 (Iddings and Cross, 1885, p. 111). Reports of monazite in the crystalline rocks first begin to appear as a result of the pegmatite investigations of the early 1940’s and mainly refer to mineral occur- rences. The search for radioactive deposits in the 1950’s turned up further minor occurrences in the crys— talline rocks, but more importantly, it disclosed large fossil placers in sandstone of Late Cretaceous age. One of the significant implicatiOns of the fossil placers is that monazite must be a more common minor acces- COLORADO sory mineral in the old schists and gneisses than it is now known to be. carsmumn BOOKS The principal occurrences of monazite in crystalline rocks have been reported from Larimer County south to Saguache County. Most of these are in pegmatites and are of no economic consequence. Pegmatite dikes associated with granite in the vicin- ity of the Copper King mine, Larimer County, were reported to contain monazite (Phair and Antweiler, 1954, p. 93). Pegmatite dikes in the Park Range, Routt County, have accessory monazite, seemingly of a rather low tenor in thorium oxide because the alpha count of this monazite is low (J afi’e and others, 1959, p. 128). Monazite from Boulder County is known as a minor accessory mineral in pegmatite dikes related to the Silver Plume Granite at Jamestown (Hanley and others, 1950, p. 21; Heinrich and Bever, 1957, p. 11). At the Rusty Gold cerite prospect on Central Gulch about 2 miles northeast of Jamestown, monazite and other rare-earth minerals are associated with cerite in the potassium feldspar core of a zoned and banded body of biotite-muscovite pegmatite 30 feet long and 2-5 feet thick. The core zone reaches a maximum thickness of 16 inches and contains from 2 to 5 per- cent of RE203 in very fine grained aggregates domi- nantly composed of cerite and allanite with which small quantities of bastnaesite, toernbohmite, monazite, and uraninite occur. Aplitic phases bearing monazite are also known. The composition of the rare-earth and thorium oxide precipitate from monazite from an aplite-pegmatite vein in the Jamestown area, Colorado, was analyzed spectrochemically (Murata and others, 1957, p. 148) and found to be lean in thorium oxide. Recalculated to 68.08 percent, the abundance of the rare earths and thorium oxide in this monazite (H. J. Rose, Jr., 1958, oral commun.) is as follows: Percent La203 _____________________________________ 8. 57 C802 ______________________________________ 27. 06 PTGOH _____________________________________ 3. 98 ngOa _____________________________________ 21. 46 8111203 _____________________________________ 2. 90 Gng:; _____________________________________ 1. 28 Y203 ______________________________________ l. 89 Th02 ______________________________________ . 94 Total ________________________________ 68. 08 Migmatitic biotite paragneiss at three localities near Central City, Gilpin County, contains minor accessory monazite and xenotime and local concentrations of these minerals (Young and Sims, 1961, p. 276—296). The concentrations range from 1 to 5 percent of the 119 volume of the rock in biotite-rich zones which have a maximum thickness of 5 feet and are several hundred feet long. Prospected localities are at Jasper Cuts about a mile south-southeast of Central City, Four- mile Gulch about three-fourths of a mile northeast of Black Hawk, and at Illinois Gulch about a mile south- southwest of Central City. At Jasper Cuts about 100 short tons of rock was mined in 1957 as an ore for the yttrium earths (Young and Sims, 1961, p. 277). The concentrations of xenotime and monazite are about 100 feet stratigraphically above the base of an intimately interlayered sequence of migmatitic biotite- quartz-plagiocl-ase gneiss and biotite-sillimanite-quartz gneiss, which overlies microcline—quartz—plagioc]ase gneiss. The biotitic and sillimanitic gneisses are inter- layered with about equal amounts of pegmatite. At each of the three localities the xenotime and monazite occur as aggregates of sand-size subrounded to rounded grains in thin biotite-rich layers. Biotite in these layers is coarse grained, and the flakes are randomly oriented in contrast to the strong preferred orientation of the biotite in the rest of the gneiss. The aggregates of xenotime and monazite are accompanied by small amounts of magnetite and zircon, but the large and varied suites of heavy minerals commonly associated with placers are not present. A more varied suite of heavy minerals is present in the gneiss than in the xenotime and monazite-rich layers. The concentrations of monazite and xenotime were interpreted by Young and Sims (1961, p. 294—296) to have formed in place late in a period of Precambrian deformation and migmatization. The pegmatite, which constitutes the felsic phase of the migmatitic paragneiss, was thought to have formed from the gneiss during plutonic metamorphism at the upper amphibolite grade and to have mobilized the rare earths and phosphate in the biotite gneiss. These components crystallized with the unoriented biotite late in the deformation of the gneiss. Other geologists have explained the concentration of monazite as a hybrid process involving the formation of migmatite by pervasive injection of pegmatitic and granitic mate- rial into paragneiss with an implicit conveyance of rare—earth minerals from some igneous source (Hein- rich, 1958, p. 270). No known igneous source exists for the monazite and xenotime in the migmatite be- cause, according to Young and Sims (1961, p. 295), intrusive granodiorite in the Central City area lacks both of these minerals, and the biotite—muscovite gran- ite in the area, though monazite bearing, was intro- duced after the monazite was formed. Monazite is a minor accessory mineral in tabular, lo- cally zoned pegmatite dikes and sills in migmatite in 120 the Clear Creek pegmatite district of southeastern Gil— pin County, northeastern Clear Creek County, and northwestern J efferson County (Hanley and others, 1950, p. 29—30; Boos, 1954, p. 124; Heinrich and Bever, 1957, p. 11). Common major accessory minerals are muscovite, biotite, beryl, tourmaline, and garnet, and the other minor accessories are chrysoberyl, apatite, magnetite, bertrandite, columbite, rutile, samarskite, pyrite, molybdenite, gadolinite, and fluorite. In the Soda Creek—Beaver Brook part of the district at least one of the bodies of monazite-bearing pegmatite also contains accessory topaz and amazonstone. A monazite-bearing granite pegmatite dike at Cen- tennial Cone, Jefferson County, intrudes granitic gneiss and mica schist (Waldschmidt and Adams, 1942, p. 29—30; Hanley and others, 1950, p. 85—86). The contacts between the dike and its wallrocks are sharp, and the walls are unaltered. The dike is about 10 feet thick and 500 feet long. For most of its length it is composed simply of quartz, microcline, and sparse muscovite, but the intermediate zone of the dike, about 40 feet long and no more than 6 inches thick, is miner- alogically complex and contains beryl, monazite, albite, bertrandite, sericite, garnet, samarskite, molybdenite, and biotite. Monazite is relatively abundant in crys- tals as much as 11/2 inches long in the mineralogically complex part of the dike (Waldschmidt and Adams, 1942, p. 32). Irregular dark-brown unidentified in— clusions in the monazite suggest that the monazite formed from an earlier precipitated mineral. Most of the coarse crystals of monazite are partly embedded in beryl, but fine—grained monazite occurs as both inclu- sions in and encrustations on crystals of beryl. Ap- parently the crystallization of beryl was interrupted by a period in which monazite, garnet, samarskite, muscovite, and molybdenite precipitated, and this period was followed by a sparse second deposition of monazite upon existing beryl crystals. The well-zoned Bigger mica-beryl pegmatite dike in the Sweitzer Gulch—Twin Forks area of Jefferson County cuts across and is locally conformable to the foliation of a mass of gneissic diorite (Hanley and others, 1950, p. 82—83; Boos, 1954, p. 124). The dike is composed of potassium feldspar, quartz, muscovite, and sparse albite and biotite. Accessory minerals are minor beryl, tourmaline, garnet, bismuthinite, bismu- tite, sulfides, monazite, columbite and tantalite. Euh- edral crystals of monazite as much as 0.5 inch across are associated with black tourmaline in the intermedi- ate zone of the dike. This zone is about 2 feet thick and at least 320 feet long. THE GEOLOGIC OCCURRENCE OF MONAZITE Monazite is a rare accessory mineral in unzoned and zoned pegmatite dikes in the South Platte area, Doug- las County (Heinrich and Bever, 1957, p. 11). Other rare accessory minerals are beryl and columbite. Minor accessory minerals are bismuthinite, bismutite, tourma- line, and pyrite, and major accessory minerals are muscovite, biotite, and fluorite. The Gutfey-Micanite area in the southeastern part of Park County and the north-central part of Fremont County is underlain by biotite schist, quartz-feldspar- biotite gneiss, quartz—sillimanite schist, amphibolite, and granite. Zoned dikes of granitic pegmatite in these rocks have a wide variety of accessory minerals among which monazite is one of the least common. These minerals include muscovite, biotite, beryl, gar- net, apatite, columbite, tourmaline, magnetite, bis— mutite, beyerite, cordierite, pinite, sillimanite, mona- zite, euxenite, and doubtful uranothorite (Hanley and others, 1950, p. 43; Bever, 1952; Heinrich and Bever, 1957, p. 12—13, 25—30, 32). Locally the monazite is intergrown with euxenite or closely associated with beryl, columbite, and muscovite. At the Boomer mine near Lake George in Park County, monazite was found in a beryl-quartz-fluorite vein in biotite gneiss adjacent to a body of granite (W. R. Griffitts, oral commun., 1960). Small mona— zite crystals are perched on crystals of beryl in a cavity surrounded by beryl. Byproduct monazite, topaz, pyrite, tin, and tung- sten minerals were recovered from the ore body at the Climax molybdenum mine in Lake County (Eng. and Mining Jour., 1951). Only about 0.005 percent of monazite is present in the ore. A diorite intrusive in sandstone and shale of Penn- sylvanian age and limestone of Mississippian age at the Calumet Iron Mine, Chaffee County, has produced a corundum—andesine-sillimanite assemblage in the shale and asbestiform diopside, actinolite, tactite, and garnet in the limestone. Vuggy masses of epidote in the contact zone were reported to be cemented by white scapolite or topaz, and crystals of monazite occur in the cavities perched on the scapolite or topaz (W. R. Griflitts, oral commun., 1960). The Yard mine about 4 miles northeast of Buena Vista in the Trout Creek—Pass area, Chaffee County, exposes a body of monazite-bearing pegmatite about 200 feet long and 50 feet Wide in coarse-grained gran- ite to which the pegmatite was said to be genetically related (Hanley and others, 1950, p. 21—22). Quartz, microcline, and sericitized plagioclase are the chief constituents of the pegmatite and have the remarkable COLORADO average grain size of about 6 feet. Accessory minerals are biotite, muscovite, monazite, and euxenite, of which monazite and euxenite are sparsely and errat- ically distributed. Monazite forms subhedral to an- hedral masses as large as 8 inches across. Other peg- matite dikes in the area contain small quantities of bismuth minerals, allanite, and euxenite, but monazite was unreported (Hanley and others, 1950, p. 22). Monazite is a minor accessory mineral in 23 (1.3 percent) of the 1,803 pegmatite dikes in the Quartz Creek pegmatite district, Gunnison County (VVem- linger, 1950, p. 92; Heinrich, 1953, p. 77; Staatz and Trites, 1955, p. 28). The pegmatite dikes for the most part occur in granite, quartz monzonite, and horn- blende gneiss. The composition of the host rocks has had little effect on the shape of the bodies of peg- matite, but the degree of competency of the hosts does. Most of the dikes lack or have only poorly differen- tiated zones and internal structures, but some are lay- ered and a few are strongly zoned (Hanley, 1946; Hanley and others, 1950, p. 19; Jahns, 1953, p. 1090). Wallrocks are Virtually unaltered at the contacts with the pegmatite dikes, and the dikes are especially lean in tourmaline, apatite, and other minerals indicative of volatile components. These observations were in- terpreted by Staatz and Trites (1955, p. 45) as indicat- ing that boron, phosphorus, and water were present in the small amounts needed to form the rare accessory minerals but not in surplus amounts. The dikes were thought to have formed by fractional crystallization in place. In the pegmatite dikes, monazite occurs as dark-red to brown euhedral crystals from a quarter of an inch to 2 inches in length (Staatz and Trites, 1955, p. 40). It is most common in the feldspar-rich parts of the few dikes in which it is found. In most of the dikes less than six grains of monazite were observed, but a dike at the Brown Derby mine contains a unit 20 feet long and a foot wide that has 2.2 percent of monazite. Elsewhere in the district exceptional local concentra- tions of monazite were observed at the Black Wonder pegmatite and Bucky pegmatite. Monazite from the Brown Derby mine contains 5.62 percent of Th02 and 0.16 percent of U308 (Tilton and Nicolaysen, 1957, p. 31). Several thorium- and rare-earth—bearing minerals have been found in veins and mineralized shear zones near an alkalic igneous complex in the Powderhorn district of Gunnison County, but monazite has only been found in a few carbonatite dikes within the com- 238—813—67—9 121 plex (Hedlund and Olson, 1961, p. B283; Olson and Wallace, 1956, p. 693—703; Jarrard, 1957 , p. 42). Pegmatites in the Villa Grove area and in the area near Crestone, Saguache County, contain monazite, euxenite, and cyrtolite (Brown and Malan, 1954, p. 11—14). rossn. PLACERS Fossil placers composed of ilmenite and accessory monazite, garnet, zircon, tourmaline, magnetite, rutile, and several unidentified opaque minerals occur inter- mittently in the upper parts of littoral marine sand- stone of Late Cretaceous age in the San Juan basin, Colorado and New Mexico (Chenoweth, 1956; 1957, p. 212), and in sedimentary rocks of the same age in Wyoming and Montana (Murphy and Houston, 1955, p. 190——194). Outcrops of the fossil placers are dis- continuously exposed for at least 700 miles subparallel to the Rocky Mountains. This distribution of detrital monazite is here interpreted to indicate that the min- eral is much more widely present in the plutonic rocks of the Rocky Mountains than the literature indicates. These fossil placers may contain Colorado’s largest known resources in monazite. The most northerly of the reported deposits in Colorado is on the flank of Grand Mesa, about 20 miles east of Grand Junction, Mesa County (Murphy and Houston, 1955, p. 190). The other reported de— posits are in Montezuma County in the southwestern part of the State and extend intermittently southeast- ward from the vicinity of Mesa Verde to Shiprock, N. Mex. (Chenoweth, 1957, p. 213). As in Wyoming and New Mexico the deposits in Colorado are ancient beach placers at transitions between marine and non- marine sedimentary rocks. They are in well-sorted marine sandstone which is overlain by lagoonal de- posits of coal and shale (Chenoweth, 1957, p. 212). In the San Juan basin the placers range in length from a few tens to several thousands of feet and in width from a few tens to several hundreds of feet (Chenoweth, 1957, p. 213). They are fine grained, well sorted, and are cemented with hematite and lim- onite. From 50 to 60 percent of the placer sand is heavy minerals, dominantly ilmenite, and the re- . mainder is quartz. In the heavy fraction the general distribution of minerals is 62—77 percent of ilmenite, 15—20 percent of zircon, 5—15 percent of garnet, and about 3 percent of various mixtures of monazite, rutile, spinel, epidote, amphibole, magnetite, and tour- maline. Fourteen fossil placers were reported in the Point Lookout Sandstone by Chenoweth ( 1957 , p. 215—216) 122 in the area between Mesa Verde, 0010., and Shiprock, N. MeX., five being in Colorado. None is well exposed, but one deposit crops out intermittently for 2% miles. It reaches 250 feet in width and 6 feet in thickness. PRESENT STREAM PLACERS Monazite was listed as a component of black sands from streams, mainly gold bearing, at Hahns Peak and Timber Lake, Routt County (Day and Richards, 1906b, p. 1192—1193; Sanford and Stone, 1914, p. 46; Schrader and others, 1917, p. 91). Only a trace of monazite was found in the concentrate from Hahns Peak, but two concentrates from Timber Lake were remarkably rich in monazite (Day and Richards, 1906b, p. 1192—1193): Pounds per short ton A B Magnetite _______________________________ 128 _______ Ilmenite _________________________________ 792 584 Garnet __________________________________ 448 512 Monazite ________________________________ 416 520 Zircon ___________________________________ Trace 80 Quartz __________________________________ 196 304 Total _____________________________ 1, 980 2, 000 This tenor of monazite in stream placers in the Western States, as reported by Day and Richards, is only equaled by two samples from Timber Lake, 0010., two samples from the Elk City district, Idaho, and a sample from Big Creek, Idaho. A trace of monazite is present in concentrates from the Central City area, Gilpin County (Day and Richards, 1906b, p. 1192— 1193). Monazite was said to occur in gold placers at New- lands Gulch and the Platte Canyon in Douglas County about 20 miles south of Denver (Kithil, 1915, p. 13). At Buena Vista in Chaffee County, black sands lean in or barren of gold were reported by Day and Rich- ards (1906b, p. 1190-1193) . Mineralogical composition, in pounds per short ton, of concen- trate from Buena Vista A B C Magnetite ______________________ 1, 012 1, 248 1, 472 lmenite ________________________ 186 462 168 Garnet _________________________ 28 83 80 Hematite ______________________ ~ _________________ 168 Olivine _________________________________ 3 ________ Monazite _______________________ 20 28 32 Zircon _________________________________ 82 56 Quartz _________________________ 664 68 24 Unidentified minerals ____________ 90 22 ________ Total ____________________ 2, 000 1, 996 2, 000 Concentrates from the San Lina Valley and the San Luis Valley, Costilla County, contain monazite TI-IE.‘ GEOLOGIC OCCURRENCE OF MONAZITE (Schrader and others, 1917, p. 91). That from the San Luis Valley has only a trace, but the concentrate from the San Lina Valley contains 30 pounds of mona— zite per short ton (Day and Richards, 1906b, p. 1192— 1193): Pounds per short ton Magnetite _________________________________ 1, 008 Chromite ________________________________ 452 Ilmenite ___________________________________ 500 Monazite __________________________________ 30 Zircon _____________________________________ 10 Total ________________________________ 2, 000 CONNECTICUT Monazite was identified in 1837 by C. U. Shepard in sillimanite gneiss exposed at the falls of the Yantic River in Norwich, New London County (Shepard, 1837a, p. 163; 1840, p. 249; 1852, p. 109; Beck, 1842, p. 452; Silliman, 1844), and in pegmatite at Water- town, Litchfield County (Shepard, 1837b, p. 342; Beck, 1842, p. 450). These seem to be the first re- ported occurrences of monazite in the United States. By 1852 monazite was known in gneiss at Chester in Middlesex County (Silliman, 1844, p. 207) and at Litchfield in Litchfield County (Shepard, 1852, p. 109). Since that time monazite has been found in about 24 pegmatite dikes (Pratt, 1905, p. 41; Dale and Gregory, 1911, p. 3; Sanford and Stone, 1914, p. 53; Schrader, Stone, and Sanford, 1917 , p. 100; Schairer, 1931, p. 55; Dake, 1955, p. 55), in old gneisses (Mining and Sci. Press, 1902) and in sand— stone of Triassic age (Krynine, 1950, p. 23). Prac- tically the entire literature on monazite in the State relates to the mineralogical occurrences in the peg- matite dikes. Economic deposits of monazite are un- known in the crystalline rocks, and the streams drain- ing the glaciated uplands are unlikely to have had access to enough monazite since the last glaciation to have formed placers. PEGMATITE Most of the reported occurrences of monazite in Connecticut are in the Middletown pegmatite district (Cameron and others, 1954, p. 5) in Hartford and Middlesex Counties. These pegmatite dikes have been said to be genetically related to the Monson Gneiss of granodioritic to granitic composition (Foye, 1949, p. 51), which occurs as bodies of variable size in staur- olite- and kyanite-bearing mica schist, but the genetic relationship seemingly is not firmly established (Rodgers, 1952, p. 415). There is a strong tendency for the pegmatite dikes to be more abundant in schist adjacent to the Monson Gneiss than in the gneiss it- CONNECTICUT self (Foye, 1922, p. 4). Some dikes cut across the contact between the schist and gneiss. Dikes in the Middletown district tend to be flat, bluntly terminated, elongate lenticular bodies having well-defined mineralogical zoning parallel to the walls (Cameron and others, 1954, p. 2; Heinrich, 1953, p. 74—75). From the walls inward the mineralogical zones comprise a quartz-muscovite-plagioclase border zone, a quartz-plagioclase-sheet muscovite zone, a plagioclase-perthite-quartz-muscovite zone with or without biotite, a perthite—quartz—plagioclase-muscovite zone with or without biotite, a perthite-quartz zone, and a quartz core. All zones are rarely present in a single dike, and in some dikes, material of the inner zones is found to fill fractures in the outer zones. Ac- cording to Cameron, Larrabee, McNair, Page, and Stewart the zonal mineralogical sequence in the dikes can best be interpreted as successive crystallization in- ward from the walls and not as replacement of exist— ing massive pegmatite. A large number of minor accessory minerals occur in the pegmatite dikes of the Middletown district. Beryl, gahnite, lepidolite, cookeite, spodumene, mag- netite, garnet, tourmaline, chrysoberyl, triplite, triphy- lite, lithiophilite, monazite, zircon, bismutite, colum- bite, samarskite, microlite, epidote, uraninite, autunite, molybdenite, and sphalerite have been reported (Hein- rich, 1953, p. 74—75; Rice and Gregory, 1906, p. 73). Monaziteis not an especially abundant accessory in the Middletown pegmatite district, but it has been reported from dikes near Glastonbury, Hartford County (Rice and Gregory, 1906, p. 73; Foye, 1949, p. 51; Sohon, 1951, p. 50), and Portland and Haddam, Middlesex County. Of the pegrnatite occurrences in Middlesex County those near Portland have been described most extensively in the literature. Three feldspar quarries and a beryl prospect at Portland are monazite bearing. The Strickland or Collins Hill quarry 2.5 miles northeast of the center of Portland exposes one of several pegmatite dikes in staurolite— and kyanite-bearing muscovite—biotite schist (Rice and Foye, 1927, p. 83—87; Schairer, 1931, p. 55; Foye and Lane, 1934, p. 130, 137; Jenks, 1935, p. 177, 181—184; Zodac, 1937, p. 134—141). The Strickland quarry is in coarse-grained pegmatite and associated graphic granite. The Pelton quarry east of the Strickland quarry opens a body of pegmatite in orthogneiss (Foye, 1922, p. 4). The pegmatite contains minor cinnamon-brown accessory monazite (Penfield, 1882, p. 250—251; Dana, 1884, p. 543; Schairer, 1931, p. 55). Two analyses of monazite from the Pelton quarry made by Penfield (1882, p. 252) showed a specific gravity of 5.20—5.25. 123 Chemical analyses, in percent, of monazite from the Pelton quarry A B Mean 0e203 __________________________ 33. 69 33. 4O 33. 54 (La, D0203 _____________________ 28. 15 28. 51 28. 33 Th0; __________________________ 8. 33 8. 17 8. 25 P205 ___________________________ 28. 19 28. 16 ' 28. 18 SiOz ___________________________ 1. 57 1. 77 1. 67 Loss on ignition _________________ . 36 . 38 . 37 Total ____________________ 100. 29 100. 39 100. 34 Dull brownish-red monazite crystals nearly an inch long are in pegmatite at the Hale quarry, also known as the Andrews quarry, north of the Strickland quarry and north of Portland (Rice, 1885; Foye, 1922, p. 6; Schairer, 1931, p. 55; Foye and Lane, 1934, p. 130). The quarry is in a large dike of pegmatite and graphic granite in orthogneiss (Zodac, 1941, p. 166—167). A large variety of minerals have been found in the dike, but most of them are minor accessories. The list as compiled by Zodac (1941, p. 166—167) includes albite, allanite, apatite, autunite, beryl, biotite, chalcopyrite, columbite, garnet, limonite, melanterite, microcline, molybdenite, monazite, montmorillonite, muscovite, pyrite, pyrolusite, pyrrhotite, quartz, sphalerite, tor- bernite, triphylite, tourmaline, uraninite, xenotime, and zircon. A crystal of monazite from the Hale quarry was analyzed by Fenner (1932, p. 330; Lane, 1932, p. 16) and found to contain 0.00 percent of U308, 8.52 per- cent of Th02, and 0.1086 percent of PhD. Monazite from Portland, possibly from the Strickland quarry or from the Hale quarry, was shown by Boltwood (1905, p. 608, 611) to have 8 percent of Th02 and 0.3 percent of U308. Monazite from Portland, locality not otherwise iden- tified, was found to contain 10.8 percent of Th02 after the analysis was recalculated to 68.3, the sum of the rare earths and thorium oxide in the monazite (H. J. Rose, Jr., oral commun., 1958): [Analysts: Murata, Rose, and Canon (1953, p. 294)] Percent 113.203 _____________________________________ 12. 9 Ce02 ______________________________________ 23. 8 PI‘gOn ____________________________________ 2. 7 Nd203 _____________________________________ 9. 8 Sm203 _____________________________________ 4. 4 Gd203 _____________________________________ 2. 1 Y203 ______________________________________ 1. 8 Th0; ______________________________________ 10. 8 Total ________________________________ 68. 3 The Hale-Walker beryl prospect is in a tabular body of pegmatite 180 feet long and 6-8 feet thick near Portland (Cameron and others, 1954, p. 324). The dike cuts across the foliation of the Monson Gneiss. 124 Quartz and perthite are the principal minerals compos— ing the dike. Subordinate plagioclase and muscovite and accessory beryl, tourmaline, columbite-tantalite, and scarce monazite are present. Monazite was reported to occur in a pegmatite dike in cordierite— and sillimanite—bearing biotite gneiss at Haddam, Middlesex County (Rice and Gregory, 1906, p. 73; Heinrich, 1950a, p. 178). The pegmatite con- sists of quartz, microcline, and albite, and has accessory tourmaline, garnet, zircon, columbite, bismutite, chrys— oberyl, muscovite, epidote, biotite, monazite, and uraninite. Branford, New Haven County, was cited as a mona- zite locality (Sohon, 1951, p. 50), but the nature of the occurrence was not specified. Several railroad cuts near Lyme, New London County, were said to expose monazite—bearing rocks, but the rock was not described (Schairer, 1931, p. 55; Sohon, 1951, p. 50). Quartz-orthoclase pegmatite at South Lyme, New London County, contains accessory monazite, sphene, tourmaline, molybdenite, and biotite (Matthew, 1895, p. 231—232; Kemp, 1899, p. 374; Loughlin, 1912, p. 127; Sohon, 1951, p. 50). The monazite tends to occur close to and in books of biotite. Monazite is present in pegmatite in the vicinity of Waterford, New Lon- don County (Schairer, 1931, p. 55; Sohon, 1951, p. 50). Monazite occurrences at Willimantic and Windham, Windham County, have been mentioned, but the kind of occurrence was not specified (Sohon, 1951, p. 50). Good crystals of monazite were reported from Oneco, Windham County, but the source was not described (Schairer, 1931, p. 55). OTHER PLUTONIG ROCKS Sillimanite schist exposed just downstream from Yantic Falls near Norwich in New London County has long been known to contain accessory monazite (Shep- ard, 1837a, p. 163; Schairer, 1931, p. 55; Foye, 1949, p. 83). Granite in the Flatrock quarry 3 miles northwest of New London, New London County, has accessory monazite, sphene, ilmenite, and aeschynite (Foye, 1949, . 83 . P Allskite associated with Sterling Orthogneiss was said to contain accessory monazite (Foye, 1949, p. 59). smnsronn Accessory detrital monazite occurs as rounded de— trital grains in sandstone of Triassic age in southern and central Connecticut, particularly in the Pomp- eraug area, New Haven County (Krynine, 1950, p. 23, 40). The monazite ranges from almost colorless to light greenish yellow and yellowish green. Scarce inclusions consist of gas—filled cavities or dark dust. ,Monazite is most common in the Triassic sedimentary THE GEOLOGIC OCCURRENCE OF MONAZITE rocks of southern Connecticut where it reaches a max- imum abundance of 4.6 percent of the heavy minerals in some sediments of the Newark Group. Other heavy detrital minerals associated with the monazite in the Triassic sediments are apatite, augite, epidote, fluor- ite, garnet, hornblende, kyanite, rutile, sillimanite, staurolite, sphene, tourmaline, xenotime( ?), zircon, and zoisite (Krynine, 1950, p. 90—91). DELAWARE Monazite was said by Nininger (1956, p. 156) to occur in buried fossil beach and bar deposits that formed during Cretaceous and Tertiary time along the Atlantic seaboard as far north as Delaware, but specific localities in Delaware were not given. FLORIDA Detrital monazite is present in very small amounts in sand throughout much of Florida (Carpenter and others, 1953, p. 789). It is more or less concentrated locally in raised spits, beaches, and dunes in eastern and northeastern Florida. It is widely distributed as a minor component of the heavy minerals in present beaches and dunes along the Atlantic coast and in present beaches and deltas along the gulf coast of Florida (Tyler, 1934, p. 3, 7; Jones, W. H., 1949a, p. 457; Lamcke, 1940, p. 89; Casperson, 1948; Trumbull and others, 1948, p. 46—47). The monazite is asso- ciated with ilmenite, rutile, zircon, and other heavy minerals which are locally abundant enough to be mined. The principal ore minerals, ilmenite and rutile, have been mined at five localities in eastern Florida. At three of these localities byproduct mona- zite has been recovered (Liddell, 1917, p. 153; Calver, 1957, p. 23; Lamb, 1955a; Mertie, 1957, p. 1767 ; Rove, 1952, p. 141). The history of this mining is summar- ized below from details given by Calver (1957, p. 15—21). Mining of the monazite-bearing beach deposits was begun by Buckman and Pritchard, Inc., in 1916 at Mineral City, now known as Ponte Vedra, St. Johns County, after exploration of the Atlantic coast from Charleston, SC, to the Straits of Florida (Martens, 1928, p. 125). Ilmenite was the only product until 1922, except that some monazite was apparently pro- duced around 1916 or 1917 (Liddell, 1917, p. 153). In 1922 the property was acquired by the National Lead Co., which began to recover zircon. During 1925 rutile was added to the other products, and in that year 1 short ton of monazite was said to have been produced (Santmyers, 1930, p. 11). Possibly this is the mona- zite reported to have been shipped from the property after World War I (Rock Products, 1929). Mining at Mineral City ceased in 1929. DELAWARE AND FLORIDA In 1940 a small amount of ilmenite, zircon, and rutile was selectively mined from monazite-bearing beach sand near Melbourne, Brevard County, by the Riz Mineral Co. Shortly thereafter the company be- gan to separate monazite from the Melbourne beach sand and to recover monazite, ilmenite, rutile, and zircon from dune sand near Vero Beach, Indian River County. After more or less continuous operation until 1946 and intermittent production to 1948 the company was reorganized under the name Florida Ore Process- ing Co., Inc., with a mineral separation plant at Palm Bay. Shortly after this reorganization the company began to process concentrates dredged by the Florida Minerals Co. from dune deposits just south of Vero Beach and dunes west of Winter Beach. In 1955 the Florida Ore Processing Co. discontinued mining but continued to treat the concentrates from the Florida Minerals Co. until October 17, 1955, when the Palm Bay plant burned. A new plant was put up near Winter Beach and the recovery of ilmenite, rutile, zir- con, garnet, and monazite was resumed in February 1956. A subsidiary of the National Lead Co. known as the Rutile Mining Co. of Florida began in August 1943 to recover ilmenite and rutile from monazite- bearing sand in Duval County between Jacksonville and the Atlantic Ocean. A plant designed to treat 8,000 short tons of sand per 20-hour day was erected by the Humphreys Gold Corp. under a lease from the Rutile Mining 00.; this plant began operation April 1, 1944. Only ilmenite and rutile were produced until 1946, when the recovery of zircon began. This plant has been in continuous operation since it was opened, and a small amount of monazite was said to have been produced there annually from concentrates that contained about 0.5 percent of monazite (Gunter, 1955, p. 54). A large body of heavy-mineral—bearing sand was discovered in 1945—46 by E. I. du Pont de Nemours and Co., Inc., on Trail Ridge in the Camp Blanding area of Clay and Duval Counties southeast of Starke in the Central Highlands of Florida (Carpenter and others, 1953, p. 789). Exploration by the US. Bureau of Mines and the Florida Geological Survey proved that the deposit contained about 4 percent of heavy minerals. Monazite is practically absent from the heavy suite. A part of the deposit on Trail Ridge in Clay County was opened in April 1949 for E. I. du Pont de Nemours and Co., Inc., by the Humphreys Gold Corp, which built a plant capable of treating 20,000 short tons of sand a day. Titanium minerals are the main product, but zircon is also recovered, and the separa- 125 tion of staurolite was begun in 1952. Sillimanite, kyanite, and andalusite are stockpiled (Browning and others, 1956, p. 2). A second and similar plant was opened for du Pont on Trail Ridge at Highland, Clay County, by the Humphreys Gold Corp. in April 1955. Monazite is not produced at either plant. Operations at these deposits are among the largest and most modern systems for the processing of placer minerals in the United States (Thompson, J. V., 1958, p. 86). In these highly mechanized operations the ancient inland buried beach and dune deposits are preferred to the Recent beach deposits despite their lower tenor, because the ancient deposits are larger, have more uniform distribution of heavy minerals, and are not as vulnerable to severe storms. Many details of the mining and beneficiation are similar at the dif- ferent properties and depend on wet-plant concentra- tion of the heavy minerals by Humphreys spirals and dry—plant separation of monomineralic fractions by electromagnetic and electrostatic separators. Monazite fromthe Florida beach placers was said by Kremers (1958, p. 2) to contain 4.5 percent of Th02 and 51 percent of RE203. According to Calver (1957, p. 25), the average is about 5 percent of Th02: analyses of five samples of detrital monazite from Amelia Island in Nassau County, Mayport in Duval County, and Ponte Vedra and Anastasia Island in St. Johns County indicated an average of 4.96 percent of ThO2 and 0.55 percent of U308. These values are very close to those reported for detrital monazite in stream placers at the western edge of the Coastal Plain in South Carolina. They are somewhat lower than the average abundance of thor— ium oxide and uranium oxide in fluvial placers in the western Piedmont of North and South Carolina. Monazite from two placers at the edge of the Coastal Plain in Aiken County, SC, contain 5.08 percent and 5.07 percent of ThOz and 0.54 and 0.51 percent of U308 (Kline and others, 1954, p. 18—20; Kaufi‘man and Baber, 1956, p. 6). The average abundance of Th02 and U308 in 53 samples of monazite from placers in streams in the western Piedmont of North and South Carolina was reported by Mertie (1953, p. 12) to be 5.67 and 0.38 percent. The similarity in the amount of thorium oxide and uranium oxide in detrital monazite from Florida and South Carolina attests to the efliciency of stream trans- port and littoral reworking in the blending of mona- zite from diverse sources. The monazite in the Coastal Plain comes from crystalline rocks exposed in three well-defined belts in the Piedmont and Blue Ridge of the Southeastern States (Mertie, 1953, pl. 1; 1957). Considerable variation in the composition of monazite 126 from different source rocks in these belts has been reported. The range in the abundance of thorium oxide in monazite from 126 samples of rock from the western Piedmont was shown in analyses by K. J. Murata and H. J. Rose, Jr. (written commun., 1958) to be 21—112 percent, and the average was 5.5. Sev— eral analyses of monazite from rocks in the Blue Ridge showed a smaller range and somewhat lower average abundance of thorium oxide. Analyses have not been made of monazite from the eastern Piedmont, but the monazite is probably not as rich in thorium oxide as that farther west. Where monazite from these diverse sources is brought together in the Coastal Plain the remarkably uniform tenor of 5 percent of Th02 is found. The small difference between this abundance of thorium oxide and the averages of 5.67 percent re- ported for fluvial placers in the western Piedmont and 5.5 percent for crystalline rocks in the western Pied— mont possibly represents the influence of monazite with less thorium from the Blue Ridge and eastern Piedmont. The near identity in the abundance of thorium oxide in detrital monazite from the Coastal Plain in Florida and in South Carolina is here tentatively interpreted to indicate that the crystalline rocks have been the source of compositionally similar monazite for a long period of geologic time and through a great depth of erosion. The detrital monazite from stream placers near the west edge of the Coastal Plain in South Caro— lina was originally deposited in sedimentary rocks of Late Cretaceous and Eocene age. Where exhumed by the present streams, this old detrital monazite contains the same amount of thorium oxide as detrital mona— zite deposited during Pleistocene and Recent time on the east coast of Florida. Possibly much of the re- cently deposited monazite on the Florida east coast has come rather directly from the sources in the Pied- mont during Pleistocene and Recent time (Martens, 1935, p. 1594), but there seems to have been no de— tectable change in the aggregate composition of the monazite on the beaches from what was laid down in Late Cretaceous and Eocene time. Levels reached by Recent erosion of the crystalline rocks are, apparently, delivering monazite of similar composition to that from rocks bared at a higher erosional level during Late Cretaceous and Eocene time. The similarity in composition between monazite in the Coastal Plain of Florida and in South Carolina is here interpreted to show that interstratal solution causes little if any loss of thorium from detrital monazite. INLAND nnrosns The inland heavy-mineral deposits of northeastern Florida consist of fossil placers along Trail Ridge in Clay County and terrace and dune deposits near J ack- THE GEOLOGIC OCCURRENCE OF MONAZITE sonville in Duval County. Two fossil placers were opened for ilmenite and other minerals on Trail Ridge, but neither has produced monazite because it is too sparse to be economically separated. It is, how- ever, stockpiled with other unseparated heavy min- erals. One of the two placers is in the Camp Bland- ing area of Clay and Duval Counties southeast of Starke, and the other is about 9 miles to the north at Highland in Clay County. The two deposits occupy only a small part of Trail Ridge, and the ridge is only a small part of the Central Highlands of Florida .(Calvar, 1957, p. 19). Trail Ridge was said (Carpenter and others, 1953, p. 790) to be part of an early Pleistocene spit that ex- tended southward from Georgia during the Sunder- land Stage when sea level was about 200 feet higher than present (Cooke, 1945, pl. 1). The formation of the placer deposits was related by Mertie (1953, p. 15) to concentration along the Sunderland and Coharie terraces, by Carpenter, Detweiler, Gillson, Weichel, and Wood to the construction of the spit, and by Roberts (1955, p. 52) to the formation of dunes along an ancient shoreline. The fossil placer at Starke is a body of fine-grained sand that is 1—11/2 miles wide and about 3 miles long; it is as much as 65 feet thick at the center, and has an average thickness of about 35 feet (Carpenter and others, 1953, p. 789). Underlying the placer is a dense woody layer consisting of unconsolidated carbonized branches, limbs, twigs, pine cones, and other vegetal debris mixed with clay. Under the woody layer is found coarse—grained sand devoid of heavy minerals. Carbonized organic debris is present throughout much of the placer. Below the water table the debris locally forms a tenaceous black cement that bonds sand layers and lenses ranging in thickness from a few inches to 40 feet. The abundance of heavy minerals in the placer near Starke varies horizontally and vertically on local scale, but the average tenor of the deposit is 4 percent of heavy minerals in the raw quartz sand. Monazite was said to be present merely as a trace (Mertie, 1953, p. 15), and the average composition of the heavy suite is as follows (Calver, 1957, p. 19): Percent . Titanium minerals __________________________ 45 Zircon _____________________________________ 15 Staurolite __________________________________ 20 Sillimanite _________________________________ 5 Tourmaline ________________________________ 5 Kyanite ___________________________________ 4 Andalusite, pyroxene, spinel, and corundum_____ 6 Total ________________________________ 100 The placer on Trail Ridge at Highland was said to be similar to the deposit near Starke (Gunter, 1955, p. 43). FLORIDA The Penholoway terrace of late Pleistocene age in Duval County about midway between Jacksonville and the Atlantic coast is the site of monazite-bearing raised marine and dune placers of low grade and large volume (Mertie, 1953, p. 15; Gunter, 1955, p. 54; Calver, 1957, p. 18). The raw sand contains about 4—5 percent of heavy minerals, and the concentrate was reported to have the following average composition (Calver, 1957, p. 18): Percent Ilmenite ___________________________________ 40 Leucoxene _________________________________ 4 Rutile _____________________________________ 7 Zircon _____________________________________ 11 Monazite __________________________________ . 5 Other minerals (mainly kyanite, sillimanite,and staurolite) _______________________________ 37. 5 Total ________________________________ 100 A sample of the heads from the washing plant was reported by Miller (1945, p. 71) to contain only a trace of monazite, but monazite is recovered during processing. According to Miller the concentrate con- sisted of the following mineral percentages: Weight Weight percent percent Enstatite _____________ 24 Monazite _____________ Trace Epidote ______________ 1 1 Rutile _______________ 5 Garnet _______________ 1 Sphene _______________ 1 Homblende ___________ 1 Staurolite ____________ 2 1 Ilmenite _____________ 26 Tourmaline ___________ 6 Kyanite ______________ 3 Zircon _______________ 3 Magnetite ____________ Trace TABLE 34,—Mineralogical composition, 127 PRESENT BEACHES AND mmns or THE ATLANTIC COAST Detrital monazite has been reported in late Pleisto- cene and Recent beach and dune sand at many places along the Atlantic coast of Florida from the vicinity of St. Marys Entrance in Nassau County to Upper Matacumba Key in Monroe County. The beaches, bars, and spits along the Atlantic coast are straight and wide and at many places are backed by a line of low dunes reached only by storm waves. The heavy minerals were said by Martens (1928, p. 127) to occur in striplike beds of black sand much wider than they are thick and much longer than they are wide. These beds are elongated parallel to the shoreline, and the largest beds are at the back of the beach at the foot of the dunes where they are formed by storm waves. A sequences of thin beds of dark sand generally alter- nates with thicker layers of light-colored beach sand. The dark layers are rarely more than 6 inches thick. They are composed of sand that is finer grained than the ordinary beach sand. The ordinary beach sand and light-colored layers between the beds of black sand contain an average of about 0.5 percent of heavy minerals. In 17 samples of monazite-bearing light-colored sand from the At— lantic beaches the heavy minerals were reported to range from 0.01 to 2.4 percent and to average 0.48 (Martens, 1935, p. 1584). The small percentage of heavy minerals in the ordinary beach sand is domi- nated by ilmenite, epidote, and hornblende (table 34). in frequency percent, of heavy-mineral fraction of monazite—bearing natural beach sand along the Atlantic coast of Florida [Modified from analyses by Martens (1935, p. 1584). Symbols used: P=0.5 percent or less; Ab, absent] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Ilmenite ________________ 42 26 27 39 28 16 41 33 30 20 32 35 39 28 33 19 30 Zircon __________________ 11 3 7 19 4 2 7 12 7 5 5 6 16 6 17 6 10 Rutile __________________ 5 3 4 4 3 2 8 5 5 5 6 5 4 4 3 1 2 Monazite- 1 P 1 1 P P 1 P P P P P 1 P 1 2 P Epidote _________________ 18 26 22 15 26 38 21 20 23 28 20 2O 20 22 25 24 21 Staurolite _______________ 7 3 3 7 5 4 4 9 10 15 20 13 7 18 4 10 10 Sillimanite ______________ 6 8 5 4 11 9 3 6 6 5 2 6 3 6 4 10 9 Kyanite _________________ 1 2 1 1 2 2 P 1 P 2 1 1 P 1 1 1 1 Hornblende ______________ 2 12 12 2 13 21 5 3 7 4 1 2 2 1 6 2 4 Tourmaline ______________ 2 3 2 4 4 3 3 6 6 1 1 5 7 4 6 3 21 8 Garnet __________________ 3 1 1 2 1 P 2 4 4 5 8 4 2 6 2 1 2 Cellophane ______________ P 10 P Ab P P Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Leucoxene _______________ 1 3 2 P 3 2 6 2 1 1 1 P 1 1 2 1 3 Sphene __________________ Ab P P Ab P 1 Ab P P P P P P Ab Ab P Ab Spinel __________________ Ab Ab Ab Ab Ab P Ab Ab Ab Ab Ab P Ab Ab Ab Ab Ab Zoisite __________________ P Ab Ab Ab P P Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Hypersthene _____________ Ab Ab Ab Ab Ab Ab Ab Ab P Ab Ab Ab P Ab Ab Ab Ab Anatase _________________ Ab P Ab Ab P Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Corundum ______________ Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab Ab P P Ab Ab Ab Muscovite _______________ Ab P 13 Ab P P Ab Ab Ab Ab Ab Ab Ab Ab Ab P Ab Andalusite ______________ Ab P Ab Ab P P Ab P Ab P P Ab P P Ab P P Chloritoid _______________ Ab P Ab P P P Ab Ab P Ab Ab Ab Ab Ab Ab Ab Ab 1. Amelia Island, Nassau County. 9. Fort Pierce, St. Lucie County. 2. 200 feet south of the mouth of the St. Johns River, Duval County. 10. Olympia Beach, Martin County. 3. Manhattan Beach, Duval County. 11. 5 miles south of J upiter, Palm Beach County. 4. Flagler Beach, Flagler County. 12. Riviera Beach, Palm Beach County. 5. Daytona Beach, Volusia County. 13. Boca Raton. Palm Beach County. 6. Cocoa Beach, Brevard County. 14. Hollywood Beach, Dade County. 7. Eau Gallic, Brevard County. 15. 10 miles north of ship channel, Miami, Dade County. 8. Melbourne Beach, Brevard County. 1617. Miami Beach, Dade County. 128 Very similar abundances of the main heavy minerals were found by Miller (1945, p. 71) in nine samples of beach and dune sands from the Atlantic coast of Florida, but only three of the samples contained mona— zite (table 35). One of these three was dune sand. TABLE 35.—Mineralogical composition, in weight per- cent, of monazite-bearing concentrates from sand on the Atlantic coast of Florida [Modified trom analyses by Miller (1945, p. 65—75). Symbol used: ______ absent] 1 2 3 Corundum ______________ Trace Trace 2 Enstatite _______________ 1 3 2 Epidote _________________ 8 3 3 Garnet _________________ 4 8 2 Hornblende _____________ Trace ________________ Ilmenite ________________ 38 5 1 36 Kyanite ________________ 1 2 1 Magnetite ______________ Trace Trace Trace Monazite _______________ Trace Trace Trace Rutile __________________ 19 15 27 Sphene _________________ Trace ________ Trace Spinel __________________ Trace Trace ________ Staurolite ______________ 2 5 20 Tourmaline _____________ Trace 1 Trace Zircon _________________ 27 l O 1. Beach south of St. Augustine, St. Johns County. 2. Beach at Matanzas Inlet, St. Johns County. 3. Vero Beach, Indian River County, rough concentrate from dune sand. Evidently the enstatite reported by Miller was counted with hornblende in the other reports on the composi- tion of concentrates from the Atlantic coast of Florida. On the Atlantic coast of Florida the fraction of the natural black—sand concentrate having a specific gravity greater than 2.85 has the following percentages of heavy minerals (Martens, 1935, p. 1585): Weight percent Amelia Island, Nassau County _______________________ 24 Beach 2 miles south of Jacksonville Beach, Duval County ____________________________________ 70 Beach 3 miles south of Mineral City, St. Johns County_- 6 South Beach, St. Augustine, St. Johns County ________ 24 Daytona Beach, Volusia County ______________________ 14 Melbourne Beach, Brevard County ___________________ 86 Hollywood Beach, Dade County ______________________ 28 In the natural concentrates the dominant minerals are ilmenite, zircon, and epidote (table 36). The mineralogical composition of the beach sand and natural black sand at the coast is more complex than the inland sand at Trail Ridge. Epidote, garnet, and hornblende, which are less stable than minerals like ilmenite, rutile, zircon, and staurolite, are present on the beaches, locally in considerable abundance, but they are scarce to absent in the fossil placers along Trail Ridge. The unstable minerals are apparently lost by intrastratal solution in the old deposits, but are replenished along the shore by material trans- THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 36.—Minera.logical composition, in percent, of black sand from the Atlantic beaches of Florida [Modified from analyses by Martens (1928, p]. 144). Symbol used: Ab, absent; P, present H N c» Quartz and feldspar ______________ 52. Ilmenite ________________________ 25. Zircon _________________________ Rutile __________________________ Monazite _______________________ Staurolite ______________________ Epidote ________________________ Garnet _________________________ Kyanite ________________________ Sillimanite ______________________ Tourmaline _____________________ Hornblende _____________________ Leucoxene ______________________ Sphene _________________________ Spinel __________________________ Corundum ______________________ Collophane _____________________ Anatase ________________________ Shell (calcite) ___________________ Total ____________________ HI-FI—l . HYPSWNQNPE" H WWowWwomwwmmmowawmw i—Ii—‘Ul @.®.WPPN H HBHNH >>>>‘ >' >' ' ucwvgcficwngHwHNQFW >...... Wcmvwcmmeqemmwoowmo >~I> 99. 8 100. 100. 1 1. Amelia Island, Nassau County. 2. Beach 3 miles north of Ponte of Vedra (Mineral City), St. Johns County. 3. Esu Gallic, Brevard County. ported in streams rising in the crystalline rocks of the Piedmont. The distribution of epidote, garnet, and hornblende is a regional feature. It was observed by Dryden (1958, p. 425) along the Atlantic coast of Georgia and the Carolinas. The persistence southward along the Atlantic coast of Florida of unstable minerals like epidote and garnet, which are not present in the older sedimentary rocks of the State and therefore must have been moved down the coast from the mouths of rivers reaching the Piedmont, was interpreted by Martens (1935, p. 1588) as evidence for a prevailing southward transport of heavy minerals. The southward variation in the com- position of concentrates from the beach sands, how- ever, is far from regular. A very great but irregular southward decrease in the relative abundance of horn- blende with concomitant increase in relative abundance of tourmaline, probably caused by extreme differences in stability between the two minerals, is the clearest evidence for southward transport. At localities where pairs of samples of natural sand and natural heavy—mineral concentrates were collected, ilmenite, rutile, and zircon were found to be relatively more abundant, and sillimanite, hornblende, and tour- maline relatively less abundant in the natural concen- trate (Martens, 1935, p. 1586). Monazite from the Atlantic beaches of Florida was described by Martens (1928, p. 133) as pale-greenish— yellow fairly well rounded grains about 0.004 inch in average diameter. A few grains as large as 0.01 inch FLORIDA have been observed as far south as Olympia Beach in Martin County and Miami Beach in Dade County (Martens, 1935, p. 1578). The monazite tends to be a little smaller than the associated zircon and much rounder than associated quartz, rutile, zircon, epidote, and ilmenite. Most of the reported occurrences of monazite on the Atlantic coast of Florida were listed in the three pre- ceding tables. Very few details about any of them are given in the literature, and there are no data on the reserves of monazite. The monazite—bearing localities in these tables for which there are little or no other data are St. Augustine, South Beach, and Matanzas Inlet, St. Johns County; Flagler Beach, Flagler County; Daytona Beach, Volusia County; Cocoa Beach, Brevard County; Fort Pierce, St. Lucie County; Olympia Beach, Martin County; the locality -5 miles south of Jupiter, Riviera Beach, and Boca Raton, Palm Beach County; Hollywood Beach and Miami Beach, Dade County; Upper Matacumba Key, Monroe County. Several of these reported occurrences of monazite are in some of the most highly developed and valuable urban areas on the east coast of the United States. They are obviously not conventional placer ground. The beach and dune sand of Amelia Island, Nassau County, just south of St. Marys entrance at the extreme northeast corner of the State, was said everywhere to show thin streaks and small amounts of monazite- bearing black sand (Martens, 1928, p. 141; 1935, p. 1566). Monazite has been found on Fernandina Beach on the island (Mines Mag., 1957). In 1957 it was reported that the Union Carbide Ore Co. was planning to dredge holdings on Amelia Island to recover ilmen- ite, rutile, zircon, and monazite (Mining World, 1957c). Several monazite-bearing localities and the first il- menite placer mine in Florida are on the 35-mile stretch of coast and coastal islands between the mouth of the St. Johns River near Mayport, Duval County, and the mouth of the North River near St. Augustine in St. Johns County (Liddell, 1917 , p. 153; Teas, 1921, p. 376; Martens, 1928, p. 127—130; Jones, W. H., 1949b, p. 580). Monazite is found in sand 200 feet south of the mouth of the St. Johns River, at Manhattan Beach, at Jacksonville Beach, and at Atlantic Beach, Duval County (Martens, 1935, p. 1566; Liddell, 1917, p. 153). Heavy minerals observed in beach sand between the mouth of the St. Johns River and St. Augustine include ilmenite, zircon, rutile, monazite, staurolite, epidote, zoisite, garnet, kyanite, sillimanite, magnetite, tourmaline, hornblende, lezucoxene, spinel, anatase, muscovite, biotite, and corundum (Martens, 1928, p. 130). 238—813—67———10 129 Mineral City, now known as Ponte Vedra, in St. Johns County about 4 miles south of Jacksonville Beach, is the site of the first placer mining in Florida, as previously mentioned. The coast at the former placer is a gently sloping beach about 520 feet wide at low tide (Liddell, 1917, p. 153—154; Martens, 1928, p. 127—130). Backing the beach are a line of dunes about 200 feet wide that reach a height of about 12 feet above high tide, and behind the dunes is a low area paralleling the coast. The mined part of the deposit was the dunes and a zone of heavy minerals about 70 feet wide along the ocean side of their base. Sand in the dune area contained enough heavy min— erals to be minable to depths as great as 50 feet below mean high tide, but the streak in front of the dunes could only be worked to a maximum depth of about 17 feet, of which the lower half was lean. The richest part of the placer deposits was in the streak at the foot of the dunes where a zone 25—35 feet wide and 2—21/2 feet thick immediately in front of the dunes contained 60 percent of heavy minerals. In general the mined parts of the placer contained about 20 percent of heavy minerals. Between 1916 when the placer was opened and 1929 when mining ceased, the workings were extended along this rich streak for distances from Mineral City of 3 miles to the north and 8 miles to the south. ‘ In the early days of the operation the raw black sand consisted of, in order of abundance, quartz, ilmenite, zircon, epidote, rutile, staurolite, monazite, kyanite, spinel, garnet, corundum, tourmaline, pyroxene, amphi- bole, feldspar, xenotime, pyrochlore, and magnetite (Liddell, 1917, p. 154). Platinum was present in small amounts, but gold was absent. Wet-plant processing of the natural black sand recovered 75 percent of the heavy minerals and gave a concentrate composed of the following percentages (Martens, 1928, p. 137): Percent Ilmenite ___________________________________________ 55 Zircon _____________________________________________ 20 Rutilc _____________________________________________ 6 Mona zite _______________________________________ ’_ _ _ 2 Staurolite, epidote and other minerals _________________ 14 Quartz ____________________________________________ 3 Total ________________________________________ 100 An estimate of the monazite reserves in the deposit was given by Liddell (1917, p. 154) as 33 million tons of raw sand with at least 0.015 percent of mona- zite, or about 5,000 tons of monazite. Virtually none of the monazite was recovered. An output in 1916—17 was suggested by the contemporary descrip- tions of Liddell, but the actual output then, if any, must have been very small, because the total United 130 States production in those years was less than 20 short tons annually, and that amount is attributed to North Carolina (Santmyers, 1930, p. 15). In 1925 the property was reported to have produced 1 short ton of monazite. After the operation ceased in 1929 the land was developed as a residential area, and the sur- face improvements are more valuable than the mona- zite that was left. Monazite is present on Anastasia Island in St. Johns County (Calver, 1957, p. 25). A narrow and discontinuous beach on the west side of the Indian River about 11/2 miles north of Ban Gallic, Brevard County, contains concentrates rich in ilmenite and rutile (Martens, 1928, p. 142; 1935, p. 1584; Rock Products, 1929). Similar narrow dis- continuous beaches adjacent to coquina bluffs else— where along the Indian River were also reported to have small, rich concentrations of heavy minerals. On the Atlantic coast south of Melbourne, Brevard County, at points 9.8 and 10.4 miles from the east end of the Melbourne causeway (J. B. Mertie, Jr., oral c0mmun., 1961) are the placers mined by the Riz Mineral Co. and the Florida Ore Processing Co., Inc., in the 1940’s for titanium minerals, zircon, and mona— zite. In Indian River County beach and dune placers on the west side of US. Route 1 near Winter Beach and dunes immediately south of Vero Beach were mined for the same minerals by the Florida Minerals Co. The deposits at Vero Beach are worked out, but the Winter Beach was being mined in the late 1950’s and early 1960’s. ransmrr BEACHES AND DELTAS or THE GULF COAST The sand on the present beaches of the gulf coast in northwestern Florida was described by Martens (1935, p. 1594) as having rounder grains and a smaller variety of heavy minerals than the coastal sand on any part of the Atlantic side of the State. Most heavy- mineral suites from the northwestern part of the gulf coast lack hornblende, epidote, and garnet. Where these minerals are present, heavy minerals are sparse. The less common heavy minerals—chloritoid, zoisite, sphene, and hypersthene—of the east coast sand are absent from gulf coast sand. Mineralogical analyses of the heavy fraction from seven samples of ordinary beach sand from the gulf coast of Florida are listed in table 37. The composition of natural black sand layers interbedded with the ordinary beach sand along the gulf coast of Florida is given in table 38. Kyanite is much more common and sillimanite is much less common in the gulf coast sand than in the Atlantic coast sand. THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 37.—-—Mineralogical composition, in percent, of concentrates from beach sand, gulf coast of Florida [Modified from analyses (samples 1—3, 7) by Martens (1935, p. 1593) and analyses (samples 4—6) by Miller (1945, p. 71, table 1). Samples 1—3 and 7 are given in vsgigh'tl percent; samples 4—6 given in frequency percent. Symbol used: __, a sen l 2 3 4 5 6 7 Corundum ............. __ -_ Trace __ .- __ -- Enstatite ______________ 1 Trace l __ .- _- 5 Epidete... , __ -_ ._ _- ._ __ 3 Garnet _______ __ _. Trace __ _. ._ Homblende __ _ Trace __ __ __ Trace Ilmenite. _ 8 23 19 22 25 32 Kyanite. _ 35 3O 45 27 22 18 _ Sillimanite _____ __ __ -- 1 2 2 _- Monarite. Trace Trace Trace . 2 . 2 . 3 Trace Rutile____ 9 10 8 10 22 Sphene. __ 1 1 Trace __ __ __ Trace Spinel. _ _ _ _ _. Trace Trace __ _ _ -. Trace Staurolite____ 40 34 22 14 15 11 14 Tourmalin 2 3 5 10 14 11 2 Zircon. _ _ _ 2 Trace 13 10 11 15 Magnetite. _. Trace Trace Trace __ __ ._ .. Leucoxene _____________ __ __ ._ 3 4 5 .. 1. Beach at Pensacola Bay 14.2 miles west of Camp Navarre, Santa Rosa County. 2. East Bay, 6 miles south of Milton, Santa Rosa County. 3. Santa Rosa Island, Santa Rosa County. 4. South of Florosa, Santa Rosa Island, Santa Rosa County. 5. 2 miles east of Phillips Inlet, Bay County. 6. Beacon Beach, Bay County. 7. Tampa, Hillsboro County. TABLE 38.—Mineralogical composition, in frequency ercent, of natural black sand from the gulf coast of Flori a [Modified from analyses by Martens (1928, p. 144). Symbol used: ._, absent] l 2 3 4 Quartz and feldspar _____ 12. 4 68. 2 41. 5 1. 1 Ilmenite _______________ 38. 0 17. 7 6. 8 16. 5 Zircon _________________ 17. 9 5. 0 6. 6 68. 6 9. 2 2. 4 1. 0 6. 6 Monazite ______________ 1. 1 . 5 . 05 1. 5 Staurolite ______________ 6. 8 1. 3 1. 9 1. 7 Epidote ________________ __ . 3 . 6 . 06 Garnet ________________ . 05 Trace . 9 1. 6 Kyanite _______________ 10. 9 3. 7 1. 0 . 6 Sillimanite _____________ . 4 . 2 . 7 . 03 Tourmaline ____________ l. 7 . 6 . 6 . 03 Hornblende ____________ _- . 2 . 05 __ Leucoxene _____________ 1. 3 . 1 . 1 . 2 Sphene ________________ _ _ _ _ Trace . 2 Spinel _________________ . 5 . 1 Trace . 1 Corundum _____________ _ _ _ _ Trace _ - Andalusite _____________ -_ __ . 1 _ _ Collophane _____________ __ __ 36. 0 1. 8 Shell (calcite) ___________ . 1 Trace 2. 3 Trace Total ____________ 100. 3 100. 3 100. 2 100. 6 1. Crooked Island, Bay County. 2. Cape San Blas, Gulf County. 3—4. Venice, Sarasota County. . The differences in mineralogical composition between gulf coast and Atlantic coast sands in Florida were attributed by Martens (1935, p. 1594) to a probable longer sedimentary history for the sand on the gulf coast. The probable longer history is indicated by the shapes of the grains of sand, which are rounder on the gulf coast than on the Atlantic coast, and by the absence from the gulf coast of common minerals such as hornblende, epidote, and garnet, which are widely FLORIDA present in the source rocks in the Piedmont. Martens postulated that the present beach sand of the gulf coast is derived mainly by wave erosion of the Pleistocene sand of the coast, which deposits were in turn reworked from the Pliocene Citronelle Formation. Destruction of the unstable detrital minerals was ascribed mainly to interstratal solution- in the permeable Citronelle Formation. Addition of fresh hornblende, epidote, and other unstable heavy minerals to the beaches by streams was said to be prevented because only one stream, the Appalachicola River, presently reaches the metamorphic rocks in the Piedmont, and its outlet is a delta in a bay, and apparently little of the present load reaches the outer beaches from the delta and bay (Tanner and others, 1961, p. 1080). The unusual abundance of kyanite in heavy—mineral suites from beaches in northwestern Florida and the sparseness of sillimanite is here interpreted to indicate that the ultimate source of the heavy minerals on this coast was the crystalline rocks of western Georgia and eastern Alabama. Notable amounts of kyanite are a distinguishing feature of heavy-mineral concentrates from streams in Harris County, Ga. (Espenshade and Potter, 1960, p. 103), and from the main stem of the Chattahoochee River in Georgia (Cazeau and Lund, 1959, p. 53). Sillimanite is much less common in this region than it is in the Piedmont of North and South Carolina. Monazite grains from the gulf coast are small and well rounded (Miller, 1945, p. 69). They are colorless to pale yellowish brown or greenish brown. Most of the monazite—bearing localities that have been men- tioned in the literature are listed in the two preceding tables._ The occurrences at Pensacola Bay, East Bay, and Santa Rosa Island in Santa Rosa County have not been described in detail, although in the 1940’s the area was apparently sampled by the U.S. Bureau of Mines (Miller, 1945, p. 68). On the north side of Santa Rosa Island opposite Camp Walton, thin narrow strips of heavy minerals are found along the shore (Martens, 1928, p. 147), and it may be that this is the kind of material that was sampled. No additional information is available on the monazite-bearing sand in the Tampa area, Hillsboro County. Layers of heavy minerals, possibly as much as several feet thick, form dark hard partings in interbedded quartz sand cemented by carbonized organic debris exposed at the base of blufl’s which rise about 20 feet above Chotawhatchee Bay near Haseman, Walton County (Haseman, 1921, p. 7 5—7 7). About 80-90 percent of the deposit is sand mixed with some 5-20 percent of organic debris and small amounts of clay. 131 Where the organic debris is wet it is black and solid, but where it is dry it is brown and friable. The vegetal layers extend into the water of Chotawhatchee Bay. On its landward side the deposit is surrounded by large fresh-water lakes and swamps. The layers of heavy minerals were reported to contain ilmenite, rutile, zircon, and monazite, but the abundance of the minerals is not described. The association of heavy minerals with carbonized organic debris resembles the placers at Trail Ridge, but the age of the organic debris at Chotawhatchee Bay is not known. Haseman (1921, p. 76-77) inferred that the deposit might have formed after the area was settled by Europeans, because a part of a mast in which a lag screw and square iron nail were set was dug up about 60 feet from the edge of the bluff and 8 feet below sea level. The location of the mast would place it in the organic layer, but the fact that the vegetal matter in the layer is carbonized and the mast was not would seem to preclude contemporaneity. Dark minerals locally form thin coatings over the white sand of Inlet Beach on the gulf shore for dis- tances of 2 miles to the east and 5 miles to the west of Phillips Inlet, Bay County and lValton County (Mar— tens, 1928, p. 147). These coatings are impermanent, changing with every storm, and are formed by the wind drying the surface sand and sweeping the light grains away. At the back of the beach a more per- manent deposit is found. It consists of alternate dark layers of heavy minerals and light layers of quartz sand. Monazite is present, and staurolite and kyanite are more common at Inlet Beach than farther east around Crooked Island and Cape San Blas. Beach sand in a zone from 16 to 40 miles west of Panama City, Bay County, was explored for heavy minerals including monazite in the 1950’s (J. B. Mertie, Jr., oral commun., 1961; Lenhart, 1956, p. 69). ' Thin layers of heavy minerals containing monazite have been described on the shoreward side of Crooked Island along St. Andrews Sound, Bay County (Mar— tens, 1928, p. 145). These small deposits lie between the low tide and high tide lines and are evidently formed by the sorting action of small waves because the locality is sheltered from storms. On the gulf side of Crooked Island, thin layers of heavy minerals are also found, but thicker layers are also present. The layers are most common on the upper beach near the foot of dunes and apparently were deposited during storms. Staurolite and kyanite are particularly com— mon in the heavy sand on Crooked Island. None of the deposits was thought by Martens to be large enough to mine. 132 Thin layers of heavy minerals extend northward for some miles along the back of the gulf beach near the fronts of dunes between Cape San Blas to St. Joseph Point, Gulf County (Martens, 1928, p. 145). The concentrates are present only along the part of the beach reached by storm waves or very high tides. They are neither wide enough nor thick enough for mining. The distribution of heavy minerals in the vicinity of Cape St. George and the mouth of the Appalachicola River, Franklin County, was investigated by Tanner, Mullins, and Bates (1961, p. 1082—1086), who found that the Appalachioola River seems to be delivering a larger quantity of heavy minerals to its mouth than is accounted for by the amount of heavy minerals on adjacent modern beaches and barrier islands. Along- shore currents and wave energy at the mouth of the river seem to be inadequate to counteract the trans- porting capacity of the river current. Large shoals have been built up off the present mouth of the Appalachicola and at positions in the Gulf of Mexico off Cape St. George and Cape San Blas. The large shoals seem to mark former positions of the river mouth. The degree of sorting of the sand and the loca- tion of the heavy minerals in the vertical profile of the shoals were interpreted by Tanner, Mullins, and Bates (1961, p. 1086) to show that the sand on the shoals has not been normally winnowed. It seems to have been rearranged locally by storm waves. When the reworked sand settled after storms, the heavy minerals and coarse-grained quartz were deposited first, settled near the base of the redeposited sand, and were covered by fine sand containing scant heavy min- erals. Surface samples of sand from the shoals and other parts of the delta area disclose low average abundances of heavy minerals (Tanner and others, 1961, p. 1083—1084). Two groups of samples from the shoal at Cape St. George averaged about 0.45 percent of heavy minerals: the average of 38 samples was 0.48 percent and that of 77 samples was 0.43 percent. Seventeen samples from the shoal east of St. George Island averaged 0.15 percent of heavy minerals. In St. George Sound the heavy minerals in bottom sediments reached a maximum of 0.55 percent near the mouth of the river and decreased eastward. One sample from the bottom of the Gulf of Mexico just west of the northwest end of St. George Island contained 0.8 percent of heavy minerals. The richest samples contained only 1—1.5 percent of heavy minerals and came from the Cape St. George area. The average composition of the heavy—mineral frac- tion from samples of sand from the surface of the shoal THE GEOLOGIC OCCURRENCE OF MONAZITE near Cape St. George was reported by Tanner, Mullins, and Bates (1961, p. 1082—1083) as follows: Percent A B Ilmenite, magnetite __________________________ 33. 0 39. 7 Epidote ____________________________________ 12. 1 7. 7 Kyanite ____________________________________ 12. 0 11. 7 Staurolite ___________________________________ 6. 5 8. 3 Sillimanite __________________________________ 6. 4 (1) Hornblende _________________________________ 5. 8 4. 0 Leucoxene __________________________________ 5. 7 (2) Rutile ______________________________________ 5. 7 6. 7 Zircon ______________________________________ 4. 9 5. 7 Tourmaline _________________________________ 4. 1 5. 4 Garnet _____________________________________ 1. 3 (1) Monazite ___________________________________ 1. 3 5. 3 Other minerals ______________________________ 1. 2 5. 5 1 In other minerals. 2 Included with ilmenite. A. Average of 38 samples. B. Average of 10 samples which had a mean tenor of 1.2 percent of heavy minerals. At depths of 12—15 feet below the tops of the shoals the sand may contain 4 percent or more of heavy minerals if the sand was actually reworked as inferred. The central shoal off Cape St. George may contain as much as 20 million short tons of heavy minerals among which there may be 2.5 million short tons of monazite (Tanner and others, 1961, p. 1086). Large amounts of monazite-bearing locally zircon- rich black sand have been reported to occur on the gulf beach at Venice, Sarasota County (Martens, 1928, p. 143; J. B. Mertie, Jr., oral commun., 1961). The heavy minerals are especially conspicuous in an area extending southward about 2 miles from Casey Pass, and the main concentrations occur between the beach ridge and the high tide line. GEORGIA Monazite seems to have been discovered in the 1880’s in some of the placer gold workings in northeastern Georgia (Eng. and Mining Jour., 1888, p. 2), but it was not mined in the State, even at the height of the industry in the Carolinas in the late 1800’s and early 1900’s (Santmyers, 1930, p. 15). For the most part the Georgia gold placers do not contain monazite. It is most commonly found as a minor accessory mineral in crystalline rocks in the central part of the Pied- mont, in stream sediments on crystalline rocks, in the unconsolidated sediments of the Coastal Plain and in the beds of streams flowing therein, and on the beaches of the Sea Islands along the Atlantic coast. Probably the best potential economic sources of monazite in the State are on the Sea Islands, in Coastal Plain sediments in the extreme southeastern part of the State, and locally along the inner edge of the Coastal Plain. GEORGIA CRYSTALLINE ROCKS The principal areas of monazite-bearing crystalline rocks in Georgia were defined by Mertie (1953, pl. 1; 1957, p. 1767) as occupying two belts, one in the cen- tral Piedmont and the other in the Blue Ridge. In the central Piedmont the belt extends southwestward from Hart County and Elbert County, at the border with South Carolina, to Troup County at the Alabama line as part of a much longer belt of monazite-bearing crystalline rocks observed by Mertie from Alabama to Virginia. Throughout the belt the monazite occurs in granitic rocks, pegmatite, granitic gneiss, migmatite, and middle and upper amphibolite facies schists and gneisses of original sedimentary origin. Not all the rocks in the belt, however, are monazite bearing. The belt in the Blue Ridge and adjacent areas was observed by Mertie in Rabun and Hall Counties in the extreme northeastern part of Georgia and has been observed as a discontinuous trace in parts of North Carolina and Virginia. The monazite-bearing rocks in the Blue Ridge belt of Mertie are plutonic gneisses, schists, granite, and pegmatite. Mertie (1953, p. 22—23) reported that granite gneiss, schist, and pegmatite exposed at four localities near Bowersville, Hart County, in the main belt are mona- zite bearing. Elsewhere in Hart County exposures discovered by Mertie to be monazite bearing include gneissic pegmatite and granite south of Hartwell and granite southeast of Royston (Mertie, 1953, p. 22—23). Monazite was reported as scarce in the crystalline rocks, principally biotite schist and sillimanite schist (Grant, 1958, pl. 1), and very scarce in the commercial muscovite pegmatite dikes of the Hartwell district, Hart County (J ahns and others, 1952, p. 31). In Elbert County a monazite-bearing dike of granite is exposed 2.5 miles southwest of Dewy Rose (Mertie, 1953,p.23). Accessory monazite was reported from granitic gneiss near Danielsville, granite near Carlton, and gneiss near Colbert in Madison County, and pegmatite near the line between Madison and Clarke Counties (Mertie, 1953, p. 22—23). Granite from the west side of the Liberty quarry northeast of Lexington, Oglethorpe County, was shown to contain accessory monazite. Granite gneiss in the county is also monazite bearing (Mertie, 1953, p. 22). Monazite was found in 1949 and 1952 by Mertie (1953, p. 21—22) in granite near Athens, Barber Creek, and Princeton, Clarke County. In 1953 Parizek (1953, p. 24—25) described a body of monazite-bearing granite intrusive into garnetiferous biotite schist and migma- tite in Clarke County. The granite is massive, medium to coarse grained, and locally porphyritic. It consists principally of quartz, perthite, orthoclase, sodic plagio- 133 clase, muscovite, and biotite with accessory zircon, monazite, tourmaline, rutile, and magnetite. Numerous coarsely crystalline pegmatite dikes, sheets, and vein networks composed of orthoclase, albite, quartz, and muscovite occur in the schist adjacent to the granite. Gneissoid biotite granite intrusive into sillimanite schist in the Athens area, Clarke County, has dominant accessory xenotime, monazite, and zircon, with subor- dinate accessory hornblende, epidote, staurolite, garnet, magnetite, and sillimanite (Hurst, 1953, p. 246—249). Near the contacts between the granite and the wall- rocks, the relative abundance of xenotime, monazite, and zircon declined and that of ep‘idote and sillimanite increased. Garnetiferous sillimanite-bearing staurolite schist and garnetiferous staurolite-bearing sillimanite schists in the metamorphic aureole around the granite at Athens contain small amounts of accessory monazite and xenotime, but monazite was not reported from sillimanite-free schists. Banded gneiss northeast of Monroe, Walton County, and granite and migmatite in the vicinity of Coving- ton, Newton County, contain accessory monazite (Mer- fie,1953,p.20—22). In Spalding County monazite-bearing granite has been found near Zetella, and in Meriwether County granite and granite gneiss near Greenville, the Snelson Granite near Harris, Durand, and Warm Springs, banded granite gneiss near Gay, and mica gneiss near Woodbury were shown to contain monazite (Mertie, 1953,p.20—22). Four samples of granite, three samples of granite gneiss, and a sample of gneiss from the La Grange area, and one sample of granite gneiss from a locality near West Point, Troup County, were reported to be monazite bearing (Mertie, 1953, p. 21—22). Monazite is present as an accessory mineral in a granite stringer in augen gneiss from a point just east of a mica mine 31/2 miles northwest of Yatesville, Upson County, in the Thomaston-Barnesville pegma— tite district (Mertie, 1953, p. 21). Monazite was reported to be very scarce in the gneisses and schists of the Thomaston-Barnesville district and to be absent from the commercial muscovite pegmatite dikes of the district (Jahns and others, 1952, p. 31; Heinrich and‘ others, 1953, p. 331), but at the Colbert mine about 9 miles northeast of Thomaston, monazite has been found in mica pegmatite (J. B. Mertie, Jr., oral commun.,. 1961). Pegmatite in northwestern Crawford County con- tains minor accessory monazite (Fortson and Navarre, 1959,p.1309). Two samples of granitic gneiss from the vicinity of Franklin and one from Texas, Heard County, were 134 found by Mertie (1953, p. 21) to contain monazite; massive granite exposed west of Sharpsburg, Coweta County, is monazite bearing. Concentrates from granite exposed at Stone Mountain, De Kalb County, contain the following percentages of heavy minerals: [Analystz Hurst (1953, p. 259)] Percent Percent Monazite and zenotime- 5 Hornblende ___________ 2 Epidote ______________ 5 Apatite ______________ 1 Muscovite ____________ 5 Tourmaline ___________ 35 Magnetite ____________ 3 Garnet _______________ 40 Zircon _______________ 2 Sillimanite ___________ 2 Total __________ 100 Granite and pegmatite exposed near Clermont, Hall County, in the Blue Ridge monazite belt of Mertie contains accessory monazite (Mertie, 1953, p. 21-22). STREAM SEDIMENTS IN THE PIEDMONT AND BLUE RIDGE PROVINCES Monazite is present in varying quantities in the unconsolidated sediments in the valleys of streams rising in the two monazite belts in Georgia, and it per- sists downstream beyond the limits of the belts. The largest number of monazite-bearing streams in the Piedmont and Blue Ridge physiographic provinces are in the central Piedmont belt. Investigations of mona- zite deposits in sediments in the present valleys of the Oconee River, Flint River, and Chattahoochee River were made by the US. Geological Survey in 1952. The results of these investigations, summarized in the following paragraphs, showed that detrital monazite progressively decreased in abundance southwestward along the belt and that deposits in tributaries to the Chattahoochee River are leaner in monazite than deposits in tributaries to the Oconee River. This southwestward decrease in abundance of detrital mona— zite in the stream seems to be related to a decrease in the amount of monazite in the bedrock, which is paralleled by a decrease in regional metamorphism from sillimanite—almandine and staurolite-kyanite sub- facies in the basin of the Oconee River to staurolite- kyanite subfacies in the basin of the Chattahoochee. The fluviatile monazite placers in an area of 310 square miles in the drainage basin of the Oconee River in parts of Oconee, Barrow, Clarke, Jackson, and Oglethorpe Counties were examined by P. K. Theobald, Jr., and J. W. Whitlow of the US. Geological Survey in 1952 (P. K. Theobald, J r., written commun., 1954). The streams examined included Marburg Creek, tribu- tary to the Apalachee River in Barrow County; Sandy Creek, Falling Creek, and Barrow Creek which join the Oconee River in Oglethorpe County; Rose Creek, Wildcat Creek, and Porters Creek, which enter the Oconee River in Oconee County; Butler Creek, Barber Creek, and McNutt Creek, tributaries to the Middle THE GEOLOGIC OCCURRENCE OF MONAZITE Oconee River in Oconee County; Bear Creek and other streams entering the Middle Oconee River in Clarke County; Beech Creek, which flows into the Middle Oconee River in Barrow County; and Barbers Creek, Cedar Creek, and Hawk Creek, tributary to the Mulberry River in Barrow County. Most of the area in Barrow and Oglethorpe Counties drained by these streams is underlain by a migmatite complex of biotite schist and sillimanite schist invaded by granite. Parts of the area in Clarke and Oconee Counties are under- lain by a large body of granite having migmatitic wall zones. The investigated parts of these counties can be divid- ed on a basis of detrital heavy minerals into three major mineralogic provinces: a magnetite-rich zircon- bearing province associated with granite and gneiss in Barrow County, a monazite—rich province in Oconee County and Clarke County, and a magnetite-rich prov- ince associated with granite in Oglethorpe County. Small amounts of monazite and epidote are present in the two magnetite-rich suites. The greatest variety of heavy minerals is in the monazite—rich province which is associated with high-rank metamorphic rocks, the migmatite complex, and granite. The minerals include ilmenite, magnetite, rutile, garnet, zircon, monazite, sillimanite, amphibole, and epidote. Many of the streams are entrenched in their lower reaches and have broad flood plains as much as 2000 feet wide in their middle and upper reaches. The average thickness of alluvium in the flood plains is about 12 feet and the greatest thickness of alluvium is about 20 feet. Clayey sediments are commonly near the top of the sequence of alluvium. The sequence grades downward from clay to sand and silt with local thin layers of gravel overlying weathered crystalline rocks. The average composition of the sequence of flood-plain sediments is 3 percent of gravel, 41 percent of sand, 24: percent of silt, and 32 percent of clay. Because of the low proportion of gravel, the flood- plain sediments are unfavorable for monazite placers. Monazite was present in 93 percent of 55 samples of gravel and 69 percent of 41 samples of sand and other materials taken in the drainage basin of the Oconee River. The average tenor of the samples of gravel was 2.1 pounds of monazite per cubic yard, and of the sam- ples of sand, silt, and clay about 0.7 pound of monazite per cubic yard. The highest tenors in monazite were observed in three areas underlain by the migmatite complex: at the heads of McNutt and Bear Creeks, lower Barber Creek and the head of Butler Creek, and on central Rose Creek, the head of Wildcat Creek, and lower Porters Creek. These high-tenor areas seem to have monazite placers that are suitable for small-scale GEORGIA mining. The large flood plains, except those on the Middle Oconee River and Barber Creek, are developed on biotite schist that is a poor source for monazite; hence, they are not economic placers. Large flood plains on parts of the Middle Oconee River and Barber Creek may contain as much as 0.7—1 pound of mona- zite per cubic yard of alluvium. Stream sediments in the valleys of eastern tributar- ies to the Flint River in an area of 210 square miles in parts of Spalding County and Pike County were ex- amined for monazite in 1952 by D. W. Caldwell (writ- ten commun., 1954) of the US. Geological Survey. From north to south the streams studied are Heads Creek, Shoal Creek, Wildcat Creek, and Flat Creek in Spalding County, and Honey Bee Creek, Birch Creek, and Elkins Creek in Pike County. These streams are underlain by biotite gneiss, biotite schist, and biotite granite. About 5 miles south of the mouth of Elkins Creek, the Flint River flows across quartzite which, because of its resistance to erosion, has formed a local base level to which the Flint River is graded. Upstream from the quartzite many of the tributaries to the Flint River have low gradients and are swampy to their sources. The flood plains are commonly nar- row and discontinuous, between 100 and 1,100 feet wide and a few hundred yards to 2 miles long. Allu— vium in the flood plains ranges in thickness from 7 to 20 feet and averages 13 feet. It consists of a thin sheet of unconsolidated quartz-pebble gravel or pebbly sand resting on weathered bedrock and overlain by coarse sand, clayey fine sand, and clay. Only about 1 percent of the sediment in these valleys is gravel; 36 percent is clay. Monazite makes up 1 percent or more of the heavy- mineral concentrates from ’ the southern headwater tributaries to Shoal Creek east of Grifl'in, Spalding County, southward to the upper parts of Elkins Creek southwest of Zebulon, Pike County. In Heads Creek and the lower part of Elkins Creek, monazite is pre- sent as less than 1 percent of the concentrate. Locally the concentrates contain as much as 20 percent of mon- azite, but in most areas they contain less than 10 per- cent of monazite. Typical monazite-bearing concen- trates from this area consist mainly of ilmenite with some magnetite and rutile and a few percent of mona- zite. Small amounts of zircon, garnet, kyanite, mag- netite, tourmaline, spinel, and epidote are variably present. Detrital monazite from a tributary to the Flint River in Spalding County, collected by J. B. Mertie, J r., and analyzed by F. C. Grimaldi of the US. Geo- logical Survey, was reported to contain 4.42 percent of 135 T1102 and 0.26 percent of U308 (Mertie, 1953, p. 12). The small amount of gravel in the streams in Spalding and Pike Counties has a tenor in monazite that ranges from 0.6 to 6 pounds of monazite per cubic yard, but the other fluvial sediments contain less than 0.5 pound of monazite per cubic yard. None of these streams seems to be a commercial source for monazite. Fluvial sediments in the valleys of eastern tributar- ies to the Chattahoochee River in an area of 660 square miles in Troup County, western Meriwether County, and northern Harris County, Ga., were sampled for detrital monazite in 1952 by D. W. Caldwell (written commun., 1954) of the US. Geological Survey. Streams examined include Yellowjacket Creek, Flat Creek, Beach Creek, and Flat Shoals Creek in Troup and Meriwether Counties; Wilson Creek, Maple Creek, and Long Cane Creek in Troup County; Sulfur Creek in Meriwether County, and House Creek, Mountain Creek, and Palmetto Creek in Harris County. Mona- zite is absent from Wilson and Maple Creeks, sparing- ly present in a small proportion of the concentrates from Yellowjacket Creek, Flat Creek, and Long Cane Creek, and present in low tenors in most concentrates from the other streams. Flat Shoals Creek has the most monazite of any of the streams, but even it seems to have no possibilities as an economic source of placer monazite. The crystalline rocks in the drainage basins of these streams consist of gneisses and schists of high meta- morphic grade and some granite in Troup, Meriwether, and northern Harris Counties; they are separated by a north—northeast—trending fault near Mountain Creek, Harris County, from the Pine Mountain Series of me- dium to low-grade metasedimentary rocks south of the fault (Hewett and Crickmay, 1937, p. 31; Stose and Smith, 1939). The main monazite-bearing streams flow on biotite gneiss, biotite schist, injection gneiss, and granite in the southeastern part of Troup County, southwestern Meriwether County, and the extreme northern part of Harris County north of the fault. In the northern two—thirds of Troup County and north- western Meriwether County, streams with little or no monazite flow mainly on the Snelson Granite. A very little monazite has been found in streams south of the fault in Harris County. These minor occurrences of monazite may be recycled detrital material from little patches of Tertiary(?) sedimentary rocks in terraces on Pine Mountain. Flood plains along the large streams between Pine Mountain and the northern part of Troup County characteristically range greatly in width along their middle and lower reaches and are of uniform width in 136 the upper reaches. The flood plains of small tributar- ies to the Chattohoochee River widen downstream. Widths of 500—-1,500 feet are common in the upstream parts of the large creeks, whereas the lower ends of the flood plains are only 150—350 feet Wide. The thickness of the flood-plain deposits is commonly 10—18 feet, in a few places 20 feet, and averages 12.6 feet. The flu- vial deposits form a sequence that grades downward from silt and clay at the top of the flood plain to coarse sand and gravelly sand overlying weathered bedrock. Relative abundance of the components of the sequence are 4 percent of gravel, 47 percent of sand, 15 percent of silt, and 34 percent of clay. Heavy-mineral concentrates from the tributaries to the Chattahoochee form three distinct suites which are related to the source rocks. A suite in which mon- azite, zircon, and rutile are common, ilmenite is abun- dant, and magnetite is very variable in occurrence comes from streams which flow on the granite and high-grade gneiss, schist, and injection gneiss in the southeastern part of Troup County, southwestern Mer- iwether County, and the extreme northern part of Har- ris County. A suite in which monazite is scarce, magnetite is abundant, and ilmenite, epidote, and amphibole are common comes from streams draining areas underlain chiefly by Snelson Granite in Troup County. A suite in which monazite is absent or scarce, magnetite is scarce, epidote and amphibole are absent, ilmenite is common, and kyanite is abundant comes from streams that flow over rocks of the Pine Moun— tain Series in Harris County. Several other heavy minerals are sporadically present in one of the suites and scarce in or absent from the other suites. These minerals include xenotime, spinel, tourmaline, garnet, sillimanite, and staurolite. The variation in their occurrence also conforms to the source rocks and fits the three suites defined by the main heavy minerals. Concentrates from areas of gneiss and migmatite where there is the most monazite contain only 1—12 percent of monazite. These concentrates in only a few places contain more than 6 percent of monazite, and the tenors of the most favorable fluvial sediments are generally 0.1—0.5 pound of monazite per cubic yard. These tenors are too low for economic recovery of the monazite in the eastern tributaries to the Chattahoo- chee River in Georgia. , Heavy sand from Dukes Creek and from the Chat- tahoochee River about 4 miles below the mouth of Dukes Creek in White County was said to contain minor amounts of monazite and dominant garnet (Z0- dac, 1953, p. 57). Small quantities of magnetite, rutile, and zircon were present in the concentrates THE GEOLOGIC OCCURRENCE OF LIONAZITE from both localities, and staurolite was a minor com- ponent of the sample from the Chattahoochee River. Monazite was observed in black sand from gold placers at the Glade mine and elsewhere in stream sand in the vicinity of The Glades, Hall County (Eng. and Mining Jour., 1888, p. 2; Teas, 1921, p. 6). The Glades, ac- cording to Mertie (1953, p. 26), is an abandoned town- site, formerly the center of a gold placer camp. In extreme northeastern Georgia, detrital monazite occurs with placer gold in Rabun County (Dennis, 1898, p. 487; Pratt, 1907b, p. 109; Sterrett, 1907a, p. 109; Teague and Furcron, 1948). Concentrates from the placer were estimated by D. B. Sterrett to contain about 40 percent of monazite, and the monazite was said to have 4 percent of ThOZ (Pratt, 1916, p. 40). Apparently the deposit was never mined for monazite because there is no record of monazite having been produced in Georgia. The localities at The Glades, Dukes Creek, and Rabun County are in part of the Blue Ridge belt of monazite-bearing crystalline rocks defined by Mertie (1957, p. 1767). UNCONSOLIDATED SEDIMENTS or THE COASTAL PLAIN PROVINCE Unconsolidated sediments of Cretaceous and Ter- tiary age at the inner edge of the Atlantic Coastal Plain physiographic province in Georgia consist large- ly of debris derived from the crystalline rocks of the Piedmont and Blue Ridge. The main units of these sediments in which detrital monazite has been found are the Tuscaloosa Formation of Cretaceous age and the McBean and Barnwell Formation of Eocene age (Dryden, 1958, p. 393). Terrace deposits of Tertiary (?) age are found at high places on the Piedmont as far as 20 miles inland from the present west edge of the Coastal Plain. Gravel from one of two sampled terraces on Pine Mountain, Harris County, contains monazite (D. W. Caldwell, written commun., 1954). Unconsolidated sediments of late Pleistocene to Recent age in the eastern part of the State, especially sand on the Pamlico terrace and Silver Blufi' terrace, have been reported to contain monazite (Neiheisel, 1962, p. 368). The abundance of monazite in 40 samples of sand from the Tuscaloosa Formation, 11 from the McBean Formation, and 22 from the Barnwell Formation, in the western part of the Coastal Plain in Georgia, was estimated from the radioactivity of concentrates by Dryden (1958, p. 394, 407—409). For these estimates it was assumed that monazite was the dominant source of radioactivity. Inferred tenors of the natural sand were calculated from the estimated abundance of mon- azite in the concentrate. The results of the investiga- tion showed that 15 samples (37 percent) from the Tuscaloosa Formation, 4 samples (36 percent) from GEORGIA the McBean Formation, and 1 sample (4. percent) from the Barnwell contained more than 0.25 pound of monazite per cubic yard of sediment. Coarse sand and gravelly sand at the base of the Tuscaloosa For- mation contained the most monazite, about 2 pounds per cubic yard, of any of the unconsolidated rocks. Mineralogical study of the samples revealed that all the concentrates contain about the same suite of heavy minerals (Dryden, 1958, p. 393—394, 425). At least half of the concentrate is commonly ilmenite and leucoxene, and the rest is made up of highly variable percentages of other minerals, which in approximate order of abundance are zircon, rutile, monazite, stau- rolite, kyanite, sillimanite, tourmaline, and spinel. Unstable minerals such as garnet, epidote, and horn— blende are not present. To concentrates lacking un- stable minerals, Dryden gave the name restricted suite. He found that the restricted suite was characteristic of the unconsolidated sediments of the Coastal Plain that are older than late Pleistocene. Upper Pleisto- cene and Recent unconsolidated sediments contain both unstable and stable heavy minerals. Sand from the Tuscaloosa and Barnwell Formations exposed west of Augusta in Richmond County, from these formations plus the McBean in McDuifie, War- ren, Glascock, and Jefferson Counties, and from the McBean and Barnwell Formations around Waynes- boro in Burke County was observed by Dryden (1958, p. 422) to be somewhat leaner in monazite than that from the same units elsewhere in Georgia. Only 2 out of 31 samples contained more than an estimated quarter of a pound of monazite per cubic yard of sed- iment. In part of these same areas, however, particu- larly around Thomson, McDuflz'ie County, some highly radioactive zones have been detected by airborne radio- activity survey (Schmidt, 1961). Some of the Coastal Plain sedimentary rocks around Thomson were shown by Mertie (1953, p. 13, pl. 1) to contain more than usual amounts of monazite. The results of the air- borne survey indicate that samples might be selected in the Thomson area that would be considerably richer in monazite than 0.25 pound per cubic yard. Three out of five samples of sand from the Tusca- loosa Formation and two out of three samples from the McBean Formation exposed around Sandersville, Washington County, were estimated by Dryden (1958, p. 407—408) to contain more than 0.25 pound of mon- azite per cubic yard. Sand from the Barnwell Forma- tion, sampled at seven places in the Sandersville area, had less than a quarter of a pound of monazite per cubic yard. 137 The Tuscaloosa and Barnwell Formations exposed in areas west and southwest of Milledgeville, Baldwin County, including parts of Jones and Wilkinson Coun- ties, were found by Dryden (1958, p. 407—408) to be lean in monazite. Small amounts of monazite were reported by Dryden (1958, p. 407—408) to be present in sand from the Tus- caloosa and Barnwell Formations exposed in parts of Bibb, Twiggs, and Jones Counties at and north of Dry Branch, Bibb County. A microscopic examination by B. F. Laney of the US. Geological Survey of a sam— ple of clay from a pit near Dry Branch was reported to have disclosed a very large variety of extremely fine—grained accessory minerals including quartz, feld- spar, wad, limonite, muscovite, magnetite, hematite, ilmenite, zircon, rutile, apatite, tourmaline, corundum, and monazite (Sproat, 1916, p. 14). Most of these grains passed through a 260-mesh sieve, and some were much finer. The size and species of the heavy minerals indicates that this is a restricted suite of detrital grains like that noted by Dryden (1958, p. 425) in the Tuscaloosa, McBean, and Barnwell Forma- tions and that the minerals were deposited with the clay in a sedimentary environment. Several clay de- posits in the Dry Branch area are bleaching clays or ful- ler’s earth (Lang and others, 1940, p. 19—20, 263—268) and may be bentonitic. There seems to be scant pos- sibility, however, that the monazite in this clay is of pyroclastic origin because the clay is interbedded with sand that contains detrital monazite. The Tuscaloosa and Barnwell Formations outcrop- ping in Bibb and Peach Counties southwest of Macon and the Tuscaloosa Formation between Knoxville, Crawford County, and Butler, Taylor County, are lean in monazite (Dryden, 1958, p. 407—408). In parts of Talbot, Marion, Chattahoochee, and Muscogee Counties east of Columbus, Ga., four out of nine sam- ples of sand from the Tuscaloosa Formation were estimated by Dryden (1958, p. 407—408) to contain more than 0.25 pound of monazite per cubic yard. At a locality near Coleman, Randolph County, a sample of sand from the McBean Formation contained an estimated 0.25 pound of monazite per cubic yard (Dry- den, 1958, p. 407—408). The heavy minerals in eight samples of sand of late Pleistocene age and nine samples of sand of Recent age exposed on marine terraces along the southeast edge of the Coastal Plain in Georgia were studied by Nei- heisel (1962, p. 368—374). He found that all the sam- ples contain monazite, but that, relative to Recent sand, the Pleistocene sand tends to be impoverished in total unstable minerals. This observation is in agreement 138 with earlier statements by Dryden (1958, p. 393—394). The average composition of these heavy-mineral suites is shown in table 39, where it can be seen that epidote TABLE 39.-—-Mineralogical composition of heavy-mineral fraction of 17 samples of sand from marine terraces in southeastern Georgia [Modified from analyses by N eiheisel (1962, p. 368, table 1)] Total heavy minerals (avg percentage of 517”" Pamlico Bluff raw sand) : terrace terrace Range _____________________________ 0. 4-2. 5 1. 1—2. 3 Average ___________________________ 1. 2 1. 7 Individual heavy minerals (avg percentage of heavy-mineral concentrate): Hornblende ________________________ . 5 . 2 Epidote ___________________________ 1. 1 6. 0 Sillimanite _________________________ 13. 6 14. 7 Ilmenite ___________________________ 43. 9 45. 3 Leucoxene _________________________ 3. 5 2. 9 Rutile _____________________________ 10. 1 6. 8 Zircon _____________________________ 15. 6 12. 8 Monazite __________________________ 1. 2 1. 6 is much less abundant in sand from the Pamlico ter- race, which was formed in middle Wisconsin time, than it is in sand from the younger and lower Silver Blufi’ terrace. The monazite-bearing samples of sand came from exposures in parts of Liberty and Bryan Coun— ties, in McIntosh County and eastern Long County, and in southern Glynn County and northern Camden County. Monazite was observed by Mertie (1953, p. 14) in six of eight samples from unconsolidated sediments of Pleistocene age in the Nahunta area, Brantly County, in one out of two samples from the Racepond area, Charlton County, and in three samples from the Jerusalem area in Charlton and Camden Counties. Anomalously high radioactivity attributable to con- centrations of monazite and other heavy minerals in the surface sand was observed in five areas in the Folkston area, Charlton County by Moxham (1954b). Three localities northeast of Folkston were thought to be concentrations formed on old shorelines during the retreat of the Wicomico sea in Pleistocene time. To the south of Folkston, however, the anomalously radio- active concentrations of heavy minerals may have been deposited by the St. Marys River. Layers of black sand were reported to be associated with tarry to pulverulent brown to black carbonized organic debris at a locality 3 miles west of St. George Charlton County (Teas, 1921, p. 377). The black sand was said to resemble, in mineralogical composition, the monazite-bearing ilmenite sands of the sea islands along the coast of Georgia. A resemblance to the Trail THE GEOLOGIC OCCURRENCE OF MONAZITE Ridge deposits in northeastern Florida is suggested by the association of heavy minerals with carbonized organic debris. STREAM SEDIMENTS IN THE COASTAL rum PROVINCE Sediments from streams that head in the Coastal Plain were found by Dryden (1958, p. 425) to be lean- er in total heavy minerals but richer in monazite than sediments from streams that enter the Coastal Plain from the Piedmont; however, no examples were given for streams in Georgia. It is probable that some streams entirely within the extreme western part of the Coastal Plain, particularly in the area from Augus- ta westward to McDuffie County, are richer in mona- zite than streams in the monazite belt in the Piedmont. A placer with gravel containing 1.5 pounds of mona- zite per cubic yard was discovered in this part of the western Coastal Plain in 1951 by Mertie (1958, p. 13). He reported the deposit to be in a small tributary to Sweetwater Creek about 3 miles east of Thomson, Mc- Duflie County. Six samples of sand from rivers that rise in the Piedmont and cross the Coastal Plain in central Georgia were reported by N eiheisel (1962, p. 368) to contain from 0.5 to 2.4 percent of heavy minerals, monazite making up about 1 percent of the concentrate, that is, about 0.005—0.02 percent of the raw sand: Percent Total heavy minerals (avg percentage of raw sand): Range _______________________________________ 0. 5—2. 4 Average _____________________________________ 1. 3 Individual heavy minerals (avg percentage of heavy- mineral concentrate): Hornblende __________________________________ 19. 3 Epidote _____________________________________ 15. 1 Sillimanite ___________________________________ 6. 7 Ilmenite _____________________________________ 33. 8 Leucoxene ___________________________________ 2. 8 Rutile _______________________________________ V 5. 7 Zircon ....................................... 9. 3 Monazite ____________________________________ 1. 0 The samples were taken from the Oconee River in Wheeler County, the Ocmulgee River in Telfair County, and at sites along the Altamaha River in Wheeler, Toombs, Tattnall, and Long Counties. Samples of sand from the Chattahoochee River where it enters the Coastal Plain at Columbus, Musco- gee County, contain a small amount of monazite from the Piedmont, and the relative abundance of the mona- zite progressively increases downstream (Cazeau and Lund, 1959, p. 57). Concentrates at Columbus contain 0.1 percent of monazite. Concentrates from down- stream localities at Fort Gaines, Clay County, and near the Florida State line at Seminole County contain respectively 0.4 and 0.9 percent of monazite (table 40). GEORGIA TABLE 40.—Mineralogical composition, in percent, of concentrates from the Chattahoochee River in the Coastal Plain of Georgia [Anaiy'sm Cazeau and Lund (1959, p. 57, table 2)] Columbus Fort Seminole Gaines County Monazite _______________________ 0. 1 0. 4 O. 9 Rutile _________________________ . 7 2. 2 3. 1 Leucoxene ______________________ 2. 9 5. 0 10. 5 Magnetite and ilmenite __________ 12. 3 18. 4 17. 6 Staurolite ______________________ 3. 6 4. 1 5. 2 Kyanite ________________________ 12. 7 13. 4 15. 1 Tourmaline _____________________ 3. 5 3. 3 3. 5 Zircon _________________________ 2. 3 2. 3 2. 0 i 18. 0 15. 0 14. 4 33. 9 31. 8 23. 7 8. 1 1. 6 2. 5 Sillimanite ______________________ 3. 5 1. 3 1. 1 Total ____________________ 101. 6 98. 8 99. 6 The relative increase downstream in the abundance of monazite is accompanied by a similar relative increase in other stable heavy minerals. This increase was in- terpreted by Cazeau and Lund (1959, p. 56—57) as being mainly the result of the removal of unstable minerals from the total heavy mineral assemblage through solution during transport. Inasmuch as the absolute abundance of the minerals is not shown by weight, the increase in relative abundance shown by the percentage does not seem to be conclusive evidence for the residual enrichment in the most stable minerals. Unless the total weights of the concentrates decline harmoniously with the increase in the relative abun— dance of the stable species, modification of the suite by addition of stable minerals from the sedimentary for- mations of the Coastal Plain cannot be ruled out. In this connection the sample at Fort Gaines might well show an increase in monazite related principally to the addition of monazite from the sedimentary rocks at the head of Cemochechobee Creek in Randolph County, where Dryden (1958, p. 418) found that the McBean Formation contains 0.25 pound of monazite per cubic yard. Although the downstream change in composition of the concentrate is certainly affected by solution, particularly in the loss of magnetite which here un- fortunately is obscured by inclusion of unstable mag- netite with stable ilmenite, some changes in the min- eralogical composition of the concentrate must also be attributable to influx of already weathered suites from the Coastal Plain rocks. BEACHES or THE SEA ISLANDS The Sea Islands, a prominent physiographic feature of the coast of Georgia, and their beaches have been widely prospected for placer deposits of the titanium ores and monazite, but virtually nothing about the re- sults of these systematic exploration programs has been 139 published. Several articles have contained discussions of the composition of natural concentrates and raw un- concentrated sand from this region, and the following comments are drawn from them (Teas, 1921, p. 37 6— - 377; Martens, 1928, p. 142-144; 1935, p. 1584—1585; Neiheisel, 1962, p. 367—368, 371—374). Two samples of natural concentrates and one sample of natural sand from the beach at Tybee, Chatham County, were examined by Martens and found to con- tain from a trace to 3 percent of monazite (table 41). Natural black sand concentrates are generally pres- ent throughout Sapelo Island, McIntosh County, and are particularly conspicuous on the beaches and in an area a short distance north of the lighthouse at the south end of the island (Teas, 1921, p. 377). Dunes on Sapelo Island were said by Teas to have scant black sand. The presence of monazite, ilmenite, and zircon, in addition to large amounts of quartz, is indicated by chemical analyses of black sand from Sapelo Island (table 42). St. Simon Island, Glynn County, was described by Teas (1921, p. 376) as having conspicuous deposits of black sand at the high tide line along the beaches. The largest of these deposits is at the south end of the island immediately in front of the lighthouse. At this locality a bed of sand 1 foot thick and half a mile long contains about 50 percent of black sand, and a layer 3 feet thick and about the same length was said by Teas to contain 2—10 percent of heavy minerals. Be- hind the high tide line the black sand is covered by dunes or a veneer of Wind-shifted sand 1—10 feet thick. A chemical analysis of black sand from St. Simon Island is given in table 42. Mineralogical analyses of three natural concentrates from the upper part of the beach and a sample of natural sand from the beach were given by Martens and are listed in table 41. Long Island, Glynn County, is separated by a marsh from the north end of St. Simon Island. Some black sand is present on the island and is most abundant near the crest of the beach ridge. A sample of natural con- centrate from Long Island was described by Martens and is listed in table 41. An excellent description of the geology of the mona— zite—bearing heavy-mineral deposits on Jekyll Island, Glynn County, was given by Neiheisel (1962, p. 371— 37 4) . His description is summarized as follows. Jekyll Island is 11 miles long from north to south and has a maximum width of 2 miles. At the north end the island is being eroded, and at its south end it is under- going accretion. Dunes and sand ridges mainly paral- lel to the present beach extend across the island and reach a maximum height of 20 feet at the south end. 140 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 41.——Mineral0gical composition, in percent, of concentrates from, beach sand and natural concentrates on Sea Island beaches of Georgia [Samples 1—2 analyzed by Martens (1928, p. 144; 1935, p. 1584—1585); samples 3—5 analyzed by N eiheisel (1962, table 1, p. 368, 372). Symbols used: Tn, trace; __, absent] Tybee, Chatham County St. Simon Island, Glynn County 163111223, Jekyll Island, Glynn County 1111 Corinty 1 1 2 1 1 1 2 1 3 1 4 5 Total heavy minerals (percent- age of raw sand) : Range ------------------ —— —- —- —— -- -- -_ __ 1. 5—22. 5 50—90 5—30 1_5 Average or individual sample ________________ 55 92 4. 6 92. 8 88 90 0. 9 93. 3 6. 0 __ __ __ Individual heavy minerals (percentage of heavy— mineral concentrate): Ilmenite _________________ 53 62 27 49. 4 55 53 24 51. 1 39. 2 51. 0 42. O 37. 2 Zircon __________________ 14 25 1 28. 6 29 31 3 27. 3 13. 2 16. 5 14 3 13. 2 Rutile __________________ 4 3 1 5. 2 4 6 2 3. 8 5. 6 7. 5 5. 8 5. 2 Monazite ................ 1 3 Tr. 4. 2 2 4 Tr 2. 2 1. 2 3. 0 1. 2 1. 5 Staurolite _______________ 4 1 4 1. 3 2 1 6 1. 4 __ 3. O 3. 8 2. 7 Epidote _________________ 15 4 33 2- 0 5 2 26 4. 2 14. 8 10. O 14. 5 16. 0 Garnet __________________ 1 1 1 . 9 1 1 Tr. 1. 0 __ 1. 0 1. 0 1. 1 Kyanite _________________ Tr. Tr. 1 . 3 Tr. Tr. 3 . 2 __ Tr 1 3 1. 6 Sillimanite _______________ Tr. Tr. 6 - 3 Tr. Tr. 6 . 4 7. 3 3. O 6 0 7, 8 Tourmaline ______________ Tr. Tr. 4 . 04 Tr. Tr. 3 . 1 __ . 5 1 3 1. 8 Hornblende ______________ 2 Tr. 12 . 1 Tr. Tr. 12 . 4 7. 1 2. 0 4. 2 9. 1 Leucoxene _______________ 2 Tr. 2 . 4 1 Tr. 2 . 5 2. 7 2. 0 2. 8 1. 5 Sphene __________________ Tr. Tr. Tr. _ _ Tr. _ _ Tr. . 05 _ _ _ _ _ _ _ _ Spinel ___________________ TI‘. TI‘. _ - . 08 TI“. Tr. _ _ Tr. _. _ _ _ __ _ _ _ Corundum _______________ Tr. -_ _- -_ -_ __ __ -- __ _- __ __ Andalusite _______________ -- -- Tr. _- __ __ __ __ _- -_ __ _- Collophane ______________ 2 Tr. 7 . 2 Tr. Tr 1 1 . 4 _ _ _ _ _ _ _ _ Anatase _________________ __ __ —— Tr. -— Tr. -- -- -- __ __ __ Zoisite __________________ __ -- Tr. —_ __ -- Tr. __ __ __ __ __ Hypersthene _____________ -- -- Tr. _— -- -_ -- __ -- __ __ __ Other minerals ........... - - - - Tr. 7- 1 - _ - - _ _ 6. 9 _ _ . 5 1. 3 1 3 1. Natural heavy—mineral concentrate. 2. Concentrate prepared from natural sand. 3. Average of 17 samples of natural sand. 4. Concentrations in ioredunes. 6. Natural dune sand. TABLE 42.—-Chemical analyses, in percent, of black sand from Sapelo Island and St. Simon Island, Ga. [Modified from Teas (1921, p. 376—377)] Sapelo Island St. Simon Island A B K20 ___________________________ 1 .06 ________________ NagO __________________________ 1 . 19 ________________ CaO ___________________________ 1.08 0.37 0.00 MgO __________________________ . 12 17 .00 A1203 __________________________ . 91 ________ . 00 6203 __________________________ .43 5.16 7.84 FeO ___________________________ .86 8.36 11.29 MnO __________________________ . 32 Trace 1.89 TiOz ___________________________ 5.55 5.23 34 .40 P305 ___________________________ .49 .28 . 18 S102 ___________________________ 85.78 80.15 43.12 Th02 __________________________ . 24 ________ . 28 06203 __________________________ .40 .18 1.5]. r0; ___________________________ . 10 . 08 . 12 l _____________________________ . 15 ________________ ______________________________ .11 ________ ________ H20 at 100° C __________________ . 18 ________________ Loss on ignition _________________ 1.03 ________________ Total ____________________ 100.00 99 .98 99 . 63 1 Given as 0.53 percent CeOg. Along the front ocean beach the direction of transport of sediment is from north to south in the direction of the predominant alongshore current. Concentrations in which heavy minerals make up as much as 75 per- cent of the sand are found at the south end of Jekyll Island in thin black surface layers on the upper beach, in thin horizontal black beds extending toward the shore beneath dunes, and in crossbedded layers in the dunes. Heavy minerals are also disseminated through the beach and dune sands in low concentrations of 1—5 percent. The average mineralogical composition of 17 samples of black sand from Jekyll Island is shown in table 41, together with examples of natural concen- trates from the upper beach and foredunes and natural dune sand. The mineral species are similar in all oc- currences on the island but differ in their degree of concentration according to their mode of deposition. The outer shore of the island, and probably of the other Sea Islands, is the most favorable location for the discovery of exploitable heavy-mineral deposits. IDAHO Displays of above-background radioactivity were ob- served by Moxham and Johnson (1953) along the Atlantic Ocean beach of Georgia. Presumably the main source of the radioactivity is monazite in littoral black sands. Four areas of above-background radio- activity are beaches described in the preceding para- graphs as being enriched in monazite: Savannah Beach in the Tybee area, Chatham County; Sapelo Island, McIntosh County; St. Simon Island immediately north of Sea Island Beach; and Jekyll Island. Above—back- ground radioactivity was also noted on the Atlantic beaches of Skidaway Island, Chatham County; Ossa- baw Island, Bryan County; and the north and south ends of St. Catherines Island, Liberty County. IDAHO Monazite was discovered in about 1896 in the Boise River basin by Waldemar Lindgren of the US. Geo— logical Survey who identified it in panned concen- trates from gold placers on Moore Creek and Granite Creek and in concentrates from lake beds near Idaho City, Boise County (Lindgren, 1897, p. 63; 1898, p. 677). He also found that monazite was present in granite adjacent to the placers; thus, with the initial identification of the detrital monazite the primary source was also found. Subsequently, occurrences of monazite were noted as far south as Oreana, Jordan Creek, and Rabbit Creek in Owyhee County (Day and Richards, 1906b, p. 1200—1201; Staley, 1940, p. 4; Hub- bard, 1955, fig.); as far north as Shoshone County (Day, 1905a, p. 9); as far west as the Clearwater River at Lewiston in Nez Perce County, and the Snake River in Adams County (Day and Richards, 1906b, p. 1200-1201; Schrader and others, 1917, p. 119) ; and as far east as Bannock County (Day, 1905a, p. 9). In 1950 monazite was discovered in pegmatite in northern Lemhi County between North Fork and Shoup, and shortly thereafter it was found to have a wide distri- bution in carbonatite in the same area (Trites and Tooker, 1952, fig. 1; Abbott, 1954, p. 3; Anderson, A. L., 1960, p. 1179). The monazite contains very little thorium, but other thorium-bearing minerals in the deposits and in the neighboring Lemhi Pass dis- trict make the Lemhi County area and adjacent parts of Montana a possible important source for thorium. Experiments directed toward the production of monazite from gold placer concentrates were said to have been begun in Idaho in the early 1900’s by the Centerville Mining and Milling Co. at Centerville, Boise County (Pratt, 1916, p. 62). No production was recorded until 1906 when 2 or 3 short tons of monazite was separated from black sand recovered at the gold placers, but this small output was not marketed (Pratt, 141 1916, p. 62—63; Sterrett, 1908b, p. 273; Cook, 1957, p. 4). During the period 1907 through 1910 similar small production was reported to have been achieved at the Centerville operation, but none of the monazite was shipped because it cost more per pound to process than the Carolina monazite (Pratt, 1916, p. 64). At least one report stated that Idaho was a factor in the mona- zite industry in the United States during the early 1900’s and attributed a small but continuous output to the Centerville plant from 1903 through 1910 (Sant- myers, 1930, p. 14). The contemporary literature, how— ever, although careful to state that records were not maintained at the Centerville operation, clearly shows that monazite from Centerville did not enter the do- mestic market. In 1910 the plant was destroyed by forest fire and was not rebuilt (Sterrett, 1911, p. 901; Staley and Browning, 1949, p. 2; Kline and others, 1950, p. 24; Kaufiman and Baber, 1956, p. 3). With the entrance of cheap, thorium oxide-rich monazite from India into world commerce in 1911 (Houk, 1946, p. 11—12), the domestic monazite mining industry closed. Except for a small supply from the Carolinas and Florida between 1915 and 1917, the United States imported monazite until the early 1950’s. Interest in domestic sources of monazite as an ore of thorium and the rare earths was renewed in the late 1940’s after India, the main supplier to the United States, placed an embargo on the export of monazite in 1946. Between 1946 and 1948 monazite-bearing jig concentrates from dredges operated by Baumhofl-Mar- shall, Inc., and the Idaho-Canadian Dredging Co. on gold placers in Grimes Creek and Granite Creek in the Boise River basin, Boise County, supplied 40 short tons of monazite (Kline and others, 1950, p. 24). Possibly some of this material was represented in the four analyses of monazite concentrates from Idaho showing 1.75—3.66 percent of ThOz published by the US. Atomic Energy Commission (George, 1949, p. 117). In mid-1948 the School of Mines at the Univer- sity of Idaho called attention to the old reports on the occurrence of monazite in the State, and an announce- ment was made that Boise and Idaho Counties alone had 200 million cubic yards of placer ground estimated to contain 0.2—0.3 percent of monazite (Mining Cong. Jour., 1948). In October 1948 the US. Bureau of Mines made a reconnaissance of the monazite-bearing gold placers in the Boise basin, and in August 1949, with support from the US. Atomic Energy Commis- sion, the Bureau commenced exploration of these plac- ers (Kline and others, 1950, p. 4—5; Griffith, 1955, p. 930). In the following year, exploration was under- taken in the Big Creek area near Cascade, Valley 142 County. Drilling on Big Creek was completed in Sep- tember 1950. In November 1950 private interests began to erect a 6-cubic-foot bucket-line dredge, and in J an- uary 1951 they commenced to mine monazite which was the only saleable product from the placer (Lamb, 1955b, p. 4; Eilertsen and Lamb, 1956, p. 25). Late in 1951 two more dredges were introduced in the Big Creek area (Kline and Carlson, 1954, p. 13). One dredge capsized in May 1953; the equipment was sal- vaged in 1954 but was not put back in operation (Kauffman and Baber, 1956, p. 11; Crawford, 1958a, p. 1157—1158). The two remaining dredges were said to handle about 4,000—6,000 cubic yards of gravel each per day and to recover about 2 short tons of monazite each per day (Lamb, 1955a). By the end of 1951 Baumhoff-Marshall, Inc., was re— ported to have shipped 1,000 short tons of monazite to the Lindsay Light and Chemical Co. (Eng. and Mining JOur., 1952b), and in the following years the total average output of the dredges in the Cascade area was expected to be 3,000—5,000 short tons of mona- zite per year (Mining Jour., 1954a, p. 97). These dredges operated until August 1955 when the United States Government stockpile requirements for monazite were filled. After that date, contracts with the Gov- ernment or private industry were no longer obtainable owing to the filling of the stockpile requirements and the resumption of imports of thorium oxide—rich mona- zite. From 1950 to 1952 the Bear Valley area in Valley County was explored by the US. Bureau of Mines (Kline and others, 1953, p. 5). The placers were found to contain monazite, euxenite, and ilmenite with small amounts of samarskite, fergusonite, columbite, and other minerals. In 1955 two dredges were installed in Bear Valley by private interests because of a demand for euxenite, and as late as 1958 byproduct monazite was being recovered (Eilertsen and Lamb, 1956, p. 25; Crawford, 1957b; Lewis, 1959, p. 1). Complete figures for the output of monazite in Idaho during the 1950’s have not been officially released ow— ing to several causes, among which are the protection of individual producer’s interests and the interests of national security. It is likely that several thousand short tons of monazite a year was produced in the State from 1952 through 1955, and a smaller output was sustained at least through 1958. CRYSTALLINE ROCKS Monazite is one of the minor accessory minerals in the Idaho batholith, and several occurrences have been mentioned, usually in connection with descriptions of detritus from the crystalline rocks (Ross, C. P., 1941, THE GEOLOGIC OCCURRENCE OF MONAZITE p. 107). A systematic discussion of monazite in the batholith, however, had not been published by the time this review was written in 1962. The scattered occur- rences that were described and the information on the composition of monazite in the placers seem to the writer to indicate that the distribution and composition of the monazite are geologically controlled, but the nature of the control is not known. Factors that suggest to the writer that the presence of monazite in the batholith is controlled by regional processes are as follows: The abundance of thorium oxide in the monazite seems to vary regionally, and the average amount of thorium oxide is low; the monazite is associated with allanite, but it has a restricted occur- rence, whereas the allanite is found throughout the batholith; the monazite is very scarce in the wallrocks; and the physical properties of the monazite are uni- form. The amount of thorium oxide in the monazite seems generally to increase southward. Abundances of 2.2 and 3.3 percent of ThOz were reported for monazite from streams in Nez Perce and Clearwater Counties (Staley, 1952, p. 308; Schrader, 1910, p. 188), and 2.7, 3.69, and 5.75 percent for monazite in central and southern Idaho County (Staley, 1952, p. 306; Kaufi'man and Baber, 1956, p. 6). These analyses of samples of monazite from localities scattered over the northern part of the west side of the batholith, or downstream from this area, average 3.3 percent of ThOz. As early as 1910 it was said that a large number of concentrates from northern Idaho, averaging about 90 percent of monazite, contained only about 3 percent of ThOZ (Schrader, 1910, p. 188). Results of 16 analyses of monazite from Valley County and 1 from Custer County in the west-central part of the batholith show from 3.31—4.84 percent of Th02 and average 4.27 per- cent of ThOZ (Kline and others, 1953, p. 20; Kline and Carlson, 1954, p. 21—22; Storch and Robertson, 1954, p. 13; Kaufl'man and Baber, 1956, p. 6). Monazite from the most southerly parts of the batholith explored in Boise and Elmore Counties has been shown in 12 analy- ses to contain from 29—624 percent of Th02 (Salt Lake Mining Rev., 1910; Sterrett, 1911, p. 902—903; Kline and others, 1950, p. 32; Kaufi’man and Baber, 1956, p. 6). Of these 12 analyses, 9 are from the Boise basin, and they have the low average tenor of 3.9 percent of T1102. The three samples of monazite from localities south of the basin have an average of 5.9 percent of ThOz, and the average of the 12 analyses is 4.4 percent of ThOz. Although there is local variation in the abundance of thorium oxide in the monazite, the 34 analyses indicate that the average amount of ThO2 in IDAHO the monazite is 4 percent, and the average content of T1102 increases from 3.3 percent in the northern part of the batholith to 4.4 percent in the southern part. The low average amount of Th02, 4 percent, is else- where in the world commonly associated with monazite occurring in granitic rocks that are not very plutonic and that are associated with regional metamorphism of low to intermediate grade, generally ranging from the albite-epidote-amphibolite facies to the kyanite— staurolite subfacies. Granitic rocks having monazite that contains about 4 percent of Th02 generally have accessory allanite. Monazite seems to be far less abundant in the batho- lith as a whole than allanite (Anderson, 1952, p. 257, 260), and where monazite is unreported allanite has generally been observed (Anderson, A. L., 1942, p. 1100, 1106-1107, 1112, 1118). In the eastern and north- ern parts of the batholith, monazite is much less com- mon than allanite, and the trend seems to continue into the separate granitic mass in the northern part of the State where granodiorite in the Pend Oreille dis- trict, Boundary County, was reported to contain alla- nite but not monazite (Gillson, 1927, p. 27). In the western and southern parts of the batholith, monazite was said to be present in more places than not, but its gross distribution is not uniform; at some places it is unaccompanied by allanite (Mackin and Schmidt, 1957, p. 2) . Allanite throughout the batholith was described by A. L. Anderson (1942, p. 1118—1119) as having been formed by endomorphic alteration under gradually changing conditions of temperature and pressure. In the opinion of Mackin and Schmidt (1957, p. 3), the radioactive minerals formed at the same time as the host rocks instead of being deposited later by hydro- thermal solutions. It is not known if the apparent antipathetic relations of monazite and allanite are genetic. For an understanding of the origin of the monazite it seems necessary to learn whether or not allanite proxies for monazite as a host for rare earths and thorium under conditions of lower temperature and pressure, either igneous or metamorphic, that do not favor development of monazite. This relationship between monazite and allanite plus sphene has been observed in the granitic rocks of the Ukrainian shield (Vainshtein and others, 1956, p. 174). The metasedimentary rocks adjacent to the batho- lith were said to be very nearly devoid of monazite ex- cept for the replacement deposits to the northeast in Lemhi County. Along the west edge of the batholith the migmatites adjacent to monazite—bearing quartz monzonite contain practically no monazite (Mackin and Schmidt, 1957, p. 2). Monazite is generally absent from the Precambrian rocks east of the batholith 143 (Staley, 1952, p. 305; Shockey, 1957, p. 8). Absence of monazite from metasedimentary rocks adjacent to monazite-bearing intrusive rocks is a common feature of relatively shallow intrusives elsewhere in the world. Monazite from different localities in the Idaho bath- olith was described by Shannon (1926, p. 411—414) as having similar physical properties. It is commonly resinuous golden yellow to amber or orange brown; very rarely it is colorless or green. The grains from most localities have the same few crystal forms, a simple crystal habit being characteristic. Inclusions are scarce, and small crystals are commonly flawless and transparent. Large grains are commonly opaque owing to multiple cracks. Such similarity in physical properties suggests a common autochthonous origin. The sporadic distribution of the monazite in the batholith, its general absence from the wallrocks, the common presence of allanite in the batholith, and the amount of thorium oxide in the monazite Seem to this writer to indicate that the monazite formed in the batholith along with the host minerals at compara- tively shallow depth. The monazite-bearing zone along the western part of the batholith seems to dis- play a regional variation in the chemical composition of the monazite that may be related to increasingly plutonic conditions of crystallization toward the south. With these inferences as a guide it is postulated in the section on “Placers” that monazite richer in tho- rium oxide than any yet found in the Idaho batholith may occur in granitic terrain south and southwest of the presently exposed south margin of the main mass of the batholith. The other principal source of thorium minerals in Idaho, the replacement and vein deposits in Lemhi County on the east side of the batholith, seem to have formed very late in the history of emplacement of the batholith or after emplacement. Probably this group of deposits is not related to the Idaho batholith. Monazite from these deposits is lean in or devoid of thorium; however, substantial reserves of thorium are present in allanite and thorite. The replacement and vein deposits have been discussed in detail in several reports, but the occurrences of monazite in the rocks of the Idaho batholith have received little close atten— tion despite the frequency with which they have been mentioned in the literature. Therefore, the descrip- tions given in the following paragraphs of monazite in the batholith are little more than locality refer- ences. Where the North Fork of the Clearwater River and Elk Creek cut through the Columbia River basalts near Dent in Clearwater County, they expose small masses of monazite-bearing granite and schist 144 (Schrader, 1910, p. 190). Schrader (1910, p. 189) noted that accessory monazite can be observed with the aid of a hand lens in granite exposed locally near Musselshell Creek, a tributary to Lolo Creek in Clear- water County. Disintegrated granite in the main val- leys of the Orofino district contains accessory mona- zite (Anderson, A. L., 1930, p. 61). The Elk City re— gion in Idaho County is underlain by biotite gneiss which was thought by R. R. Reid (1960) to be mona- zite bearing. In the Warren district, Idaho County, monazite was observed by Bell (1904, p. 224) in granite of the Idaho batholith and, in small quantities, in rich gold-quartz veins. Except for quartz veins in the Lemhi Pass area, this is the only district where monazite has been reported in quartz veins in Idaho. Porphyritic biotite granodiorite of the Idaho batho— lith exposed near the Big Creek Ranger Station and at a point 2,000 feet north-northwest of Peak 8520 near the Pilot Peak trail in the Big Creek quad- rangle, Valley County, contains accessory monazite (Jaife and others, 1959, p. 93). Granite porphyry and aplite dikes of the Idaho batholith exposed east of the south half of Long Val- ley in Valley County contain monazite, but metasedi- mentary rocks on the west side of the valley have little or no monazite (Kline and others, 1955, p. 8—9). Granite exposed in Valley County between Peace Val- ley on the Middle Fork of the Fayette River and Gar- den Valley in Boise County contains accessory mona— zite (J affe :and others, 1959, p. 95). Monazite was observed in granite in the Boise basin, Boise County, about 1896 by Lindgren (1898, p. 677). A large pegmatite dike thought to be related to the rocks of the Idaho batholith and exposed between Garden Valley and Grimes Pass, Boise County, was said to contain veinlets of almost pure monazite (Sta- ley, 1952, p. 303). Uranium, niobium, :and tantalum minerals have been found in this dike. The assem- blage of metals resembles in part that reported from the vein and lode deposits of northeastern Lemhi County, but the mode of occurrence is different. THE REPLACEMENT DEPOSITS AND VEINS Two important thorium districts are situated in northern Lemhi County, Idaho, and adjacent parts of Ravalli and Beaverhead Counties, Mont. The more northerly of the two is known as the Mineral Hill dis- trict and the other is called the Lemhi Pass district. Discovery of monazite in the Mineral Hill district was made by Trites and Tooker (1953, p. 164—186) of the U.S. Geological Survey in 1950, and deposits in the Lemhi Pass district were discovered by Vhay (1950, GEOLOGIC OCCURRENCE OF MONAZITE p. 1—17) of the Survey in 1949. In 1952 the Mineral Hill district was observed by Abbott (1954, p. 2) to be far more extensively mineralized than was noted at the time of discovery. Since then the size and origin of the deposits in both districts have received considerable attention (Sharp and Cavender, 1953; Kaiser, 1956; Weis and others, 1958, p. 39—40; Anderson, A. L., 1958, p. 21—77; 1960, p. 1180—1201). Sparse monazite was seen by Trites and Tooker in 1950 (1953, p. 164) in the plagioclase-muscovite-quartz- perthite wall zone and the perthite-plagioclase-musco- Vite—quartz intermediate zone of the Snowdrift pegma- tite dike 3 miles east of Shoup and 0.5 mile north of the Salmon River in Lemhi County. The dike, which is in porphyroblastic paragneiss, was not considered to be a source of monazite. Although this occurrence in pegmatite is the first report of monazite in the Mineral Hill district, the extensive deposits of low—thorium oxide monazite in carbonate rocks exposed between Shoup and North Fork were not discovered until 1952 (Abbott, 1954, p. 3). The carbonate rocks were first called phosphatic marble, but later work showed them to be carbonatites (Anderson, A. L., 1960). Crystalline aggregates and disseminated crystals of monazite occur in thin masses of carbonatite exposed east of the Snowdrift pegmatite. The monazite-bear- ing layers were found to be most abundant in a belt about 1.5 miles wide and 18 miles long which is part of a linear group of occurrences 2.5 miles wide and 25 miles or more long that extends northwestward from a point about 4 miles south of North Fork, Lemhi Coun- ty, at least to Woods Creek in Ravalli County, Mon- tana (Weis and others, 1958, p. 39; Anderson, A. L., 1958, p. 21). The deposits are in an area underlain mainly by biotite gneiss, schist, and amphibolite, with subordinate quartzite. Biotite gneiss is the most com- mon variety of rock. Its principal constituents are feldspar, quartz, and biotite, which vary locally in pro- portion, size, and textural arrangement. Some of the biotite gneiss is strikingly porphyroblastic and resem- bles augen gneiss or coarse-grained granite (Ander- son, A. L., 1958, p. 22). These rocks are locally in- truded by little disturbed dikes of metadiabase, two types of pegmatite, and rhyolite. One type of pegma- tite is unzoned and is composed chiefly of potassium feldspar and quartz. Locally it contains scattered grains of allanite. The other type of pegmatite, to which the Snowdrift dike belongs, is coarse grained, zoned, and contains book muscovite and sparse mona- zite. There are no rare—earth minerals in the rhyolite dikes (Abbott, 1954, p. 10). The biotitic gneisses and schists are interpreted by Abbott (1954, p. 5—10) and Kaiser (1956, p. 8) to be of IDAHO sedimentary origin. The amphibolites were regarded by A. L. Anderson (1960, p. 1182) to be intrusive gab- broic rock greatly modified by shearing and metamor- phism. Where deformation and metamorphism are least intense, the schistose and gneissic amphibolite shows transition into massive .gabbro. Abbott and Kaiser regarded the monazite-bearing carbonate rock as sedimentary limestone altered by metamorphism, but Anderson has shown by the chemical and mineralogical composition of this rock that it is a carbonatite. The regional structure of the Mineral Hill district was interpreted by Abbott (1954, p. 12) and Kaiser (1956, p. 12) to be a complex overturned synclinorium, the monazite deposits being localized in the axial parts. At its southeast end the belt of monazite-bearing rocks is intruded by granite probably related to the Idaho batholith, and the northeast edge of the gneisses is in fault contact with quartzite belonging to the Belt Series. Crystalline aggregates and disseminated crystals of monazite are associated with allanite, ilmenorutile, apa- tite, and other minerals in the carbonate veins and, to a lesser extent, in the biotitic metamorphosed sedi- ments (Anderson, A. L., 1960, p. 1184—1196). The greatest concentrations of monazite—bearing carbona- tites are on the crests or troughs of folds, and, less commonly, along the limbs of folds. Exceptionally, the monazite—rich carbonatites may reach a thickness of 8 feet and a length of 1,000 feet, but most of them are only 1 or 2 feet thick and not more than 20 feet long. Monazite in the southeastern part of the belt of de- posits contains‘more thorium and is more radioactive than that elsewhere in the district (Weis and others, 1958, p. 39). Most of the monazite was reported to be weakly radioactive and to contain less than 1 percent of Th02 (Anderson, A. L., 1960, p. 1188). Three sam- ples of monazite from the Mineral Hill district were analyzed by J affe, Gottfried, Waring, and Worthing (1959, p. 96—97) of the US. Geological Survey and found to have the low activity of 57 8—1024 alpha par- ticles per milligram per hour. An analysis by the US. Bureau of Mines disclosed 0.85 percent of T1102 and 0.003 percent of U308 (Kauffman and Baber, 1956, p. 6). The accompanying allanite is very radioactive and may contain much of the thorium in the district (Anderson, A. L., 1960, p. 1187). A. L. Anderson (1960, p. 1200) regarded the min— eral assemblage of the monazitedeposits in the Min- eral Hill district to be typical of other carbonatites and hence to have been formed by late-stage mag- matic processes. The richness of the assemblage in thorium, rare earths, phosphorus, niobium, titanium, 145 barium, calcium, iron, and sulfur is similar to the characteristic association of elements in carbonatites related to alkalic intrusives of igneous origin; how- ever, there are no known alkalic intrusives in the dis- trict. The Lemhi Pass thorium district in Lemhi County, has been described by several authors (Vhay, 1950; Trites and Tooker, 1953, p. 191—205; Sharp and Caven- der, 1953; Anderson, A. L., 1958, p. 45~58). In the following summary, the account of the geology is mainly from A. L. Anderson. The Lemhi Pass district occupies 100 square miles of the Beaverhead Range, 26 miles southeast of Sal- mon. In the district, veins and lodes of thorite as- sociated with monazite, specular hematite, barite, feld- spar zand quartz occur in folded and faulted weakly metamorphosed muscovite quartzite and biotite-chlor- ite phyllite of the Precambrian Belt Series of sedi- mentary rocks. The veins are principally composed of quartz, hematite, and thorite, with or without sul- fides. Intrusive into the Belt sediments are small dioritic and lam‘prophyric dikes of possible Late Cre- taceous or early Tertiary age. Locally the old rocks are covered by volcanic rocks of Oligocene(?) age, Tertiary lake beds, and Quaternary terrace gravels and alluvium. In some deposits the thorite and rare- earth minerals were introduced into earlier quartz veins and copper-bearing lodes. In other deposits the thorium minerals occur along previously unmin- eralized shears and fractures most of which are 40—60 feet across. Monazite, thorite, and specular hematite impregnate and replace the sheared rocks. Locally these minerals are accompanied by fine-grained seri- cite, allanite, apatite, xenotime( ’4), calcite, magnetite, biotite, and pyrite. Monazite forms small euhedral crystals or occurs as irregular-shaped inclusions in barite, feldspar, and quartz. Rarely and locally the monazite mantles thorite. The minerals in these deposits were interpreted by A. L. Anderson (1958, p. 57) to have been introduced by fluids enriched in thorium, rare earths, phosphorus, iron, potassium, barium, calcium, and sulfur, and less enriched in carbon dioxide. This association resembles end products formed from alkalic magma. It is like the association in the Mineral Hill district except that it lacks the abundant carbonate, titanium, and colum- bium present there. Also, the Lemhi Pass deposits are richer in thorium, potassium, and silicon than those at Mineral Hill. Quartz is the most common gangue min- eral at Lemhi Pass; carbonates are the most common gangue at Mineral Hill. The deposits may be related to dioritic intrusives that are younger than the Idaho batholith. 146 Monazite and thorite are present in shear zones and gold quartz veins in the Diamond Creek area, Lemhi County, about 7 miles north—northwest of Salmon (An- derson, A. L., 1958, p. 74—77). The-thorium deposits are in and adjacent to the east side of a stock of very coarse grained granite that intrudes micaceous quartz- ite and schist of the Belt Series. The mineralogy of these deposits, though complex, differs but slightly from that of the thorium deposits in the Lemhi Pass area. As far as is known the only difference is the presence of fluorite in the veins at Diamond Creek. Deposition of the minerals in the deposits in the Dia— mond Creek area was thought by Anderson to have taken place in the same order as that at the Lemhi Pass district: thorite first followed by monazite, apatite( '9), xenotime( ?), specular hematite, barite, feldspar, and quartz. These deposits, like those at Lemhi Pass, were interpreted by A. L. Anderson (1958, p. 77) to be re— lated to dioritic intrusives slightly younger than the Idaho batholith. Monazite concentrates were said to have been shipped from Hall Mountain near Porthill, Boundary County, in northern Idaho (Gillson, 1958, p. 101), but the Porthill deposits were described as thorite—bearing veins, and the presence of monazite was not indicated (VVeis and others, 1958, p. 34—35). PLACERS The mined monazite placers lie along the west side of the Idaho batholith in the west-central part of the State, but several occurrences of detrital monazite have been mentioned from other parts of Idaho. The rich— ness of the mined placers was said by Mackin and Schmidt (1956, p. 37 6—37 7 ) to depend upon the abund- ance of monazite in the rocks of the Idaho batholith and on the physiographic history of the individual drainage basin. Monazite is most common in quartz monzonitic phases of the batholith. It tends to occur in erratic microscopic segregations which contain as much as 0.3 pound of monazite per cubic yard of rock. The best placers were formed where the quartz monzo- nite has the greatest number and richest segregations of monazite, where the rock was thoroughly weathered during middle Pleistocene time, and where thick allu- vial fills accumulated under conditions allowing for maximum sorting by the streams (Mackin and Schmidt, 1956, p. 376—377). The amount of thorium oxide in monazite from the exploited placers is low by commercial standards, being only about 4: percent whereas market specifications usually demand 6 percent or more of Th02. If the apparent regional southward increase in thorium oxide in monazite from the Idaho batholith, mentioned in the THE GEOLOGIC OCCURRENCE OF MONAZITE section under crystalline rocks, is real, then it is possi- ble that the trend continues to the south of the limit of exposure of the batholith in Elmore and Camas Counties. Monazite having as much as 6 percent of ThOz may be present in granitic rocks in Owyhee and Minidoka Counties, Idaho, or, as a remote possibility, in Humboldt and Elk Counties, Nev. Systematic prospecting for monazite around granite bodies south and southwest of the exposed south margin of the batholith might disclose thorium oxide-rich monazite in workable placers. If this monazite were found, it would be a more marketable commodity than monazite from the Boise basin. The placers and known occurrences of detrital mona- zite are described in geographic order from north to south and from west to east; therefore, discussion of the economically important deposits is interspersed with descriptions of occurrences that may be scarcely more than mineralogical curiosities. SHOSHONE, LATAH, CLEARWATER, AND NEZ PERCE COUNTIES Black sand from placers at unspecified localities in Shoshone and Latah Counties was stated to contain monazite (Day, 1905a, p. 9). Detrital monazite has been reported from six locali- ties in Clearwater County: Elk River; Dent; Orofino; Orofino Creek; Pierce district including Cow Creek and Rhodes Creek; and Musselshell Creek and an area 10 miles from Weippe. N 0 information other than the location has been given for placers at the settlement of Elk River in the Elk Creek valley (Savage, 1960, fig. 1). Natural sand and placer concentrates from Dent, Orofino, and the Pierce district were reported by Day and Richards (1906b, p. 1198—1201; 1907, p. 24—— 27) to contain from a trace to 283 pounds of monazite per short ton (table 43). The placer occurrences around Dent were apparently not described in detail, though they were mentioned by Schrader, Stone, and Sanford (1917, p. 119), DeMent and Dake (1948, p. 18), and Dake (1955, p. 56). Monazite-bearing fluvial placers in the Orofino dis— trict of Clearwater County were described by A. L. Anderson (1930, p. 61—62). The placers are found along the valley floors of streams and in gravel that caps the lower ridges or forms terraces along the val- ley walls. Monazite is commonly associated with gold, garnet, magnetite, ilmenite, rutile, chromite, and zir- con. It tends to be more abundant in the lower part of the sequences of sediments, especially in gravel im- mediately above granitic bedrock. Monazite is more abundant in the old terrace gravel than in the gravel of the present stream channel. Low concentrations of monazite occur in residual soil, talus, and disintegrated IDAHO 147 TABLE 43.—Mz‘neralogical composition, pounds per short ton, in auriferous natural sand and concentrates from placers in Idaho [Modified from Day and Richards, 1906, p. 1194—1201; Tr., trace; —, absent] Sample Location County Magnetite Chromite Ilmenite Garnet Monazite Zircon Quartz Others Source 1 Dent _____________ Clearwater.- 6 280 540 414 126 _ _ 586 26 Placer concentrate. 2 _____ do ________________ do _____ Tr. 1, 432 - _ 265 52 _ _ _ _ - - Do. 1 3 _____ do ________________ do _____ 28 1, 336 - 307 283 _ _ 45 _ _ Do. 1 4 Orofino ________________ do _____ 768 __ 1, 000 20 88 76 24 20 Do. 5 _____ do ________________ do _____ 78 - - 244 40 6 2 1, 440 190 Natural sand. 6 Pierce _________________ do _____ 50 _ _ 1, 450 _ _ 94 50 226 130 Placer concentrate. 7 _____ do ________________ d0 _____ 10 6 62 28 3 3 1, 471 409 Natural gravel. 8 _____ do ________________ do _____ 1 - _ 12 11 . 1 - _ 1, 766 207 Gravel tailing. 9 _____ do ________________ do _____ 4 _ _ 106 24 Tr. Tr. 1, 528 338 Do. 1 10 _____ do ________________ do _____ 2 __ 17 4 2 __ 1, 473 499 Do. 11 _____ do ________________ do _____ 24 _ _ 1, 806 _ _ 30 30 - - 90 Placer concentrate. 3 12 Pierce district __________ d0 _____ 72 __ 1, 360 320 70 150 __ 28 D0. 13 _____ do ________________ do _____ . 2 _- 1, 189 __ 81 14 654 59 Undescribed. 14 Pierce district, _____ do _____ 3 _ _ 1, 351 199 46 - - 300 93 Placer concentrate. Cow Creek. 15 _____ do ________________ do _____ 2 __ 1, 080 413 50 . 6 358 96 Do. 16 Pierce district, ..... do _____ 48 _ _ 1, 376 _ _ Tr. 80 400 100 Do. Rhodes Creek. 17 Clearwater River, Nez Perce- - 90 __ 580 360 Tr. 30 760 160 Do. Lewiston. 18 Salmon River __________ do _____ 981 688 _ - 1 13 46 122 12 36 Undescribed. 19 Elk City __________ Idaho ______ 978 _ _ 336 _ _ 26 18 270 340 Placer concentrate. 20 _____ do ________________ do _____ 60 __ 210 10 40 10 1, 520 160 Undescribed. 21 _____________________ do _____ 208 1, 317 __ _- 108 _- 334 33 Do. 22 Elk City district--- _____ d0 _____ 1, 162 __ 428 __ 6 6 384 14 D0. 2 23 _____ do ________________ do _____ 80 _ _ 696 296 728 Tr. _ _ 200 Placer concentrate. 24 _____ do ________________ d0 _____ _ _ - _ 720 120 808 120 _ _ 104 Undescribed. 9 25 Baker Gulch, _____ do _____ 720 __ 624 __ 320 _- __ 336 Do. Crooked River. 26 Penmans Fork, ..... do _____ 640 _ _ 520 80 528 Tr. 224 _ _ Placer concentrate. Big Creek. 27 Florence _______________ do _____ _ _ _ _ 1, 520 160 Tr. - _ 320 _ _ Undescribed. 28 Marshall Lake _____ do ----- 80 _ _ 136 - - 376 1, 408 _ _ _ _ Placer concentrate. district. 29 Syringa ________________ do _____ 192 _ _ 1, 584 _ _ Tr. _ - 224 _ _ Do. 30 Camp Howard _____ do _____ 1, 285 _ _ 308 153 Tr. 100 -_ 154 D0. district. 31 Resort _________________ do _____ 196 __ 470 -_ 112 __ 638 584 Do. 32 Lardo ____________ Valley ...... 1, 480 _ _ 250 210 20 30 _ _ 10 Do. 33 Meadows _________ Adams _____ 629 564 _ - Tr. 123 392 232 _ - Do. 34 _____ do ________________ do _____ . 5 _ _ 16 4 . 1 1 1, 274 704 Undescribed. 35 Pavette River _____ Pavette- _ - _ 1, 744 _ _ 100 40 6 8 _ _ 100 Natural sand. 36 Garden Valley _____ Boise ______ 1, 864 __ 56 16 32 24 __ Tr. Placer concentrate. 37 Placerville _____________ do _____ 182 _ - 26 _ - 142 12 _ _ 42 Undescribed. 38 _____ do _________________ do _____ 68 Tr. 90 __ 36 4 __ __ Do. 39 _____ do ________________ do _____ 1, 448 -_ 198 _ - 170 34 106 44 Placer concentrate. 40 Centerville _____________ do ..... 6 18 - _ Tr. 2 Tr. 104 1, 870 Undescribed. 41 _____ do ________________ do _____ 12 __ 38 38 286 90 __ __ Do. 42 _____ do ---------------- d0 _____ 6 14 32 14 4 6 _ _ _ _ D0. 43 _____ do ________________ do _____ Tr. Tr. 8 Tr. Tr. Tr. _ _ _ _ Do. 44 _____ do ________________ d0 _____ 4 2 10 2 4 2 _ _ _ _ Do. 45 Centerville district- ..... do _____ 864 _ _ 568 128 224 100 120 _ _ Placer concentrate. l 46 Grimes Creek, _____ do _____ 264 _ _ 782 _ _ 358 - _ 556 438 Abandoned placer. Centerville district. 147 _____ do ________________ do _____ 1, 624 __ 102 __ 240 36 __ __ Do. 48 _____ do ________________ do ..... 330 _ _ 702 _ _ 68 _ _ 892 10 Undescribed. 49 _____ do ________________ do ..... 396 - _ 792 _ _ Tr. _ _ 762 52 Do. 50 _____ do ________________ do _____ 244 337 347 29 30 12 1, 251 80 Do. 51 Idaho City _____________ do _____ 82 _ _ 378 414 42 360 642 82 Do. 52 Boise area ________ Ada _______ 26 200 _ _ 709 219. 6 231 579 _ _ Do. 1 53 _____ do ________________ do ..... 540 -- 826 __ 94 34 382 124 Do. 1 54 _____ do ________________ d0 ..... 38 1 - _ 2 27. 3 27 1, 735 168 D0. 1 55 _____ do ________________ do ----- 1, 629 2 2 _ _ 58. 7 8 49 249 Placer concentrate. 56 _____ do ________________ do _____ 216 80 248 400 Tr. Tr. 1, 000 136 Undescribed. 57 _____ do ________________ d0 _____ 1, 244 -_ 344 __ 250 6 106 48 D0. 58 Oreana ___________ Owyhee- - _ _ 32 - - 1, 472 40 56 _ - 340 80 Do. 3 59 Leesburg Basin- _ _ _ Lemhi _____ 1, 807 _ _ - _ 37 20 _ _ 135 _ _ Do. 60 _____ do ________________ d0 _____ 192 _ _ 1, 340 _ _ 44 200 _ _ 224 Do. 61 _____ do ________________ do _____ 433 477 __ __ 10 __ 65 _- Do. 1 62 _____ do ________________ do _____ 1, 939 1 __ 4 . 5 . 9 8 __ D0. 63 Arnet Creek, Lees— _____ do _____ 959 832 - _ 1 16 . 5 1 _ _ - _ Do. burg Basin. See footnotes at end of table. 148 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 43.—Mineralogical composition, pounds per short ton, in auriferous natural sand and concentrates from placers in I daho—Con- Sample Location County Magnetite Chromite flmenite Garnet Monazite Zircon Quartz Others Source 64 Wards Gulch, Lemhi--- _ _ _ 747 859 _ 128 5 60 73 _ _ Undescribed. Leesburg Basin. 65 Shoshone _________ Lincoln _____ 174 15 _ _ 80 26 46 1, 441 _ _ Do. 66 Minidoka _________ Minidoka-_ _ Tr. _ _ Tr. Tr. 8 Tr. _ _ _ _ Do. 67 Snake River _______ Bingham_ _ _ 1, 032 _ _ 80 _ _ Tr. 80 _ _ 808 D0. I Lacks gold. 3 Platinum present. granite. Anderson thought that the placers were not sufficiently rich in monazite to be worked for that mineral alone but that it might be possible to recover monazite as a byproduct of gold mining, although none had been saved in the district. Orofino Creek at localities north and south of Pierce has been cited for monazite (Hubbard, 1955, fig.). These localities are probably among the ones listed by Day and Richards (1906b, p. 1200—1201), Savage (1960, fig. 1), and Shannon (1926, p. 414) for the Pierce dis- trict. Monazite placers in the valley of Musselshell Creek, a tributary to Lolo Creek in Clearwater County (by some referred to as placers 10 miles from Weippe) were described by Schrader (1910, p. 185—188), and have been cited several times since the original description (Schrader and others, 1917, p. 119; DeMent and Dake, 1948, p. 15; Dake, 1955, p. 56; Hubbard, 1955, p. 55); they have not been mined. According to Schrader the valley floor of Musselshell Creek is 250 feet wide and is covered with a sheet of Recent alluvium that aver- ages about 8 feet in thickness. Muck, sand, and clay make up the upper 3—4 feet of alluvium and overlie a layer of gravel about 4 feet thick which rests on gra- nite. Along the sides of the valley are some old gravel terraces as much as 11 feet thick. Both the old and the Recent gravel deposits are low-grade gold placers. Monazite is also present in both kinds of deposits, but it seems to be more plentiful in the terrace deposits. Other heavy minerals associated with the monazite are ilmenite, magnetite, garnet, and zircon. The monazite from the Musselshell Creek placers is fine grained, subang'ular, and splendent. It is derived from the granitic rocks of the Idaho batholith. Eleven concentrates prepared from the placer gravel by Sch- rader (1910) were found to contain from 7.5 to 45 per- cent of monazite and had a mean tenor of 29 percent of monazite. Monazite was reputed to be less plenti- ful in the gravel of Musselshell Creek than it is in the alluvium in the Pierce district (Anderson, A. L., 1930, p. 61), but by 1955 the tenors on Musselshell Creek were described as “rich” and “of commercial signific- ance” (Hubbard, 1955, p. 55). The monazite, however, is low in thorium. Analyses of four nonmagnetic fractions from con- centrates from Musselshell Creek were made by R. C. lVells (Sterrett, 1911, p. 902—903) who reported the following percentages of thorium oxide in concentrates having 87—155 percent of P205: A B C D T1102 __________________ 1. 20 1. 15 1. 85 0. 88» P205 ___________________ 10. 9 8. 9 15. 5 8. 7 Recalculated to pure monazite the analyses indicate that the monazite from Musselshell Creek contains about 3.3 percent of Th02. Schrader (1910, p. 188) commented that a large number of samples of sand from northern Idaho had been concentrated to about. 90 percent of monazite and that the concentrates were analyzed by the \Velsbach Light Co. and were found to contain about 3 percent of T1102. Streams in Nez Perce County were shown by Day (1905a, p. 9) and by Day and Richards (1906a, p. 153; 1906b, p. 1200—1201) to contain detrital monazite. They reported a trace of monazite in placer concentrates from the Clearwater River at Lewiston and 46 pounds per short ton in black sand questionably derived from the Salmon River (table 44). Sand from the Snake River between the mouth of the Clearwater River and Asotin, VVash., is monazite bearing (Staley, 1952, p. 308). A concentrate taken from the Snake River and consisting of as much as 95 percent of monazite was reported to have 63 percent of RE203, 2 percent of Th0;,, 24.4 percent of P205, and 3.9 percent of ZrOa with the remainder not listed (Staley, 1952, p. 308). IDAHO COUNTY Detrital monazite occurs in at least 12 areas in Idaho County. Most of them are in the central part of the county, but an undescribed deposit has been reported from Eldorado Creek, a tributary to Lolo Creek about 28 miles east of Greer in northern Idaho County. IDAHO The Elk City gold placers have yielded concentrates containing as much as 800 pounds of monazite per short ton of concentrate (table 43), but the tenor of the raw sand was not described (Day and Richards, 1906b, p. 1196-1199). Columbite and fergusonite were identi- fied in monazite-bearing concentrates from the Elk City district by Thomson and Ballard (1924, p. 48). Gold placers in Buffalo Gulch near Elk City were said to contain ilmenite, gold, zircon, cassiterite, and monazite (Eng. and Mining Jour., 1950a), and a con- centrate from the property of the Tyee Mining Co. near Elk City was described by Staley and Browning (1949, p. 4) as consisting of abundant ilmenite and sparse monazite. The Elk City district was sampled for monazite in the 1950’s by the US. Bureau of Mines. In a summary of the geology and heavy minerals of the placers in the Elk City district, R. R. Reid (1960) reported that the average tenor of 15 samples of stream gravels was as follows: Tenor (lb per cu yd) Allanite ___________________________________ 0. 2 Monazite __________________________________ . 15 Rutile _____________________________________ . 07 Brookite ___________________________________ . 1 Sphene ____________________________________ . 1 Zircon _____________________________________ . 25 Dmenite ___________________________________ 6. 9 Magnetite _________________________________ 16. 8 Traces of brannerite, euxenite, and columbite were found. According to R. R. Reid the volume of stream gravel in the Elk City district is 55 million cubic yards of which 25 million has already been mined for gold. Minable deposits of stream gravel are present in wide low-gradient parts of the valleys. Monazite-bearing basin deposits of Tertiary age cap some ridges and benches in the Elk City district (Reid, R .R., 1960). They crop out over an area of about 18 square miles and were said by Reid to have an average thickness greater than 60 feet and a possible volume of at least 100 million cubic yards. Four small grab sam— ples from these Tertiary rocks were found by Reid to contain an average per cubic yard of 1.6 pounds of monazite, 0.3 pound of rutile, and 0.3 pound of zircon. Baker Gulch on the Crooked River and the river itself southwest of Elk City contain placer monazite as shown on table 43 (Day and Richards, 1906b, p. 1198-1199; Hubbard, 1955, fig.). The South Fork of the Clearwater River in Idaho County was the source of a concentrate containing 55— 60 percent of monazite (Staley, 1952, p. 306). An analysis of the concentrate was said by Staley to have disclosed 37.1 percent of REzOg, 1.6 percent of ThOz, 15.2 percent of P205, and 23 percent of Zr02. The monazite alone may have about 2.7 percent of ThOg. 149 Detrital monazite has been found along four north- ern tributaries to the Salmon River in the western part of Idaho County. It is present in Crooked Creek at Dixie (Savage, 1960, fig. 1), in Penmans Fork of Big Creek (Day and Richards, 1906b, p. 1198—1199), in Lake Creek (Capps, 1940, p. 27; Kaufl’man and Baber, 1956, p. 7; Eilertsen and Lamb, 1956, p. 12), and in Grouse Creek in the Florence mining district (Reed, 1939, p. 27, fig. 4; Eilertsen and Lamb, 1956, p. 11). Little is known about any of these occur- rences except that they are all uneconomic sources for monazite. Day and Richards stated that a placer concentrate from Penmans Fork contained 528 pounds of monazite per short ton, and material from an un- described locality in the Florence district showed a trace of monazite. The Lake Creek and Grouse Creek gold placers were described briefly by Capps (1940, p. 27) of the US. Geological Survey. They were sampled by the US. Bureau of Mines in the 1950’s. Reed (1939) of the US. Geological Survey showed that only 1 concentrate out of 37 from the Florence gold mining district contained monazite. It came from Grouse Creek and had 50—60 percent of mona- zite, 35—45 percent of zircon and apatite, 4 percent of ilmenite and garnet, and 1 percent of magnetite. In Reed’s opinion the Grouse Creek monazite had no com- mercial value under the economic conditions of 1939. Southern tributaries to the Salmon River in the wes- tern part of Idaho County have been widely explored for monazite, and some of the gold placers excited interest in the early 1950’s as possible commercial sources for monazite (Eng. and Mining J our. 1950b; Hill, W. H., 1951, p. 14). The first descriptions of monazite in these streams were given by Day and Richards (1906b, p. 1198—1199), who showed that it was a conspicuous component of placer concentrates from the Marshall Lake district and was present in small amounts at Syringa and in the Camp Howard district (table 43). East and south of Burgdorf the gold placers in the basin of Secesh Creek were shown by Capps (1940, p. 27—37) to be variably monazite bearing, and the abundance of the monazite was re- lated to the bedrock geology. Farther east, in the Warren district, monazite was observed in the gold placers around Warren about 1904 (Bell, 1904, p. 224) and near Resort (table 43) by 1906 (Day and Richards, 1906b, p. 1198—1199; Bell, 1915, p. 28). The Warren district was thought by Schrader, Stone, and Sanford (1917, p. 119) to have the best monazite plac- ers in Idaho County. In 1951 an effort seems to have been made to recover monazite from the Canyon Placer near Warren (Hill, W. H., 1951, p. 14; Hub- bard, 1955, p. 55) and the meadows of Ruby Creek 150 near Burgdorf (Hubbard, 1955, p. 55). During the early 1950’s monazite deposits along southern tribu- taries to the Salmon River in western Idaho County were explored by the US. Bureau of Mines. Results of investigations in the Kelly Meadows near Burgdorf, Secesh Meadows on Secesh Creek, and the Warren Meadows in the Warren district were not published (Eilertsen and Lamb, 1956, p. 11). The most complete accounts of the geology of these placers were the re- ports by Capps (1940) on the Secesh Creek area and by Reed (1937) on the Warren mining district. According to Capps (1940), the basin of Secesh Creek is mainly underlain by epodite-bearing quartz monzonite and related rocks of the Idaho batholith with subordinate areas of gneiss, quartzite, and schist, all intruded by granite. Among the metamorphic rocks are quartz-sillimanite schist, biotite-sillimanite- garnet gneiss, and diopside-clinozoisite gneiss. These rocks are identical to those described earlier by Reed (1937) in the Warren mining district. A few small blocks of tilted and downfaulted Tertiary sedimentary rocks are preserved in structural depressions. Uncon- formably overlying the crystalline rocks and Tertiary sediments are extensive deposits of unconsolidated sedi- mentary materials of Pleistocene and Recent age in- cluding moraines from at least two stages of glaciation, terrace gravel of two or three ages, and Recent stream deposits. Locally these materials have been widely distributed and redeposited by placer mining oper- ations. The crystalline rocks in the Secesh Creek area are deeply weathered and covered by the products of disintegration and decomposition except where these have been removed by glaciation and other forms of erosion (Capps, 1940, p. 7). Valleys in the upper part of Secesh Creek and its tributaries consist typically of alternate reaches of broad, open meadows separated by narrow canyons resulting from the dislocation of the channels of the streams during glaciation. Pre—Wisconsin moraine and terrace gravel near the mouth of Three Mile Creek about 2.4 miles north of Burgdorf contain traces of monazite and zircon, abun- dant corundum, small amounts of garnet, hematite, ilmenite, and limonite, and virtually no magnetite (Capps, 1940, p. 32). The narrow part of Ruby Creek near Burgdorf is especially rich in monazite (Capps, 1940, p. 34, 37; Staley and Browning, 1949, p. 4), which occurs in sluice—box concentrates made from pre- Wisconsin moraine gravel, Wisconsin moraine gravel, and Recent gravel (table 44). Monazite and cinnabar are described as being in considerable quantity. THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 44.——Mz'neralogical composition of sluice-box concentrates from placer materials along Ruby Creek, Idaho County, Idaho [Modified from Capps (1940, p. 34). Symbols used: P, present; Ab, absent] Wisconsin Pre— moraine and Recent gravel Wisconsin underlying of Ruby moraine Lire-Wisconsin Creek gravel Quartz ___________________ Ab P P Magnetite ________________ P P Ab Ilmenite __________________ P P P Garnet- _ _ - P P P Zircon- _ _ _ P P P Monazite- _ P P P Cinnabar _________________ P P P Rutile ____________________ P Ab Ab Feldspar _________________ P P P Augite ___________________ P Ab Ab Hornblende _______________ P Ab Ab Andalusite ________________ P Ab Ab Muscovite ________________ P Ab Ab Gold _____________________ P P P Partial analyses of concentrates that have possibly 80—85 percent of monazite from Ruby Creek near Burg- dorf were reported to contain 51.5 percent of RE203, 3.2 percent of Th02, 20.6 percent of P205, and 10.1 percent of Zr02 (Staley, 1952, p. 308). Monazite from Secesh Creek was analyzed by the US. Bureau of Mines and found to contain 5.75 percent of Th02 and 0.25 percent of U303 (Kauifman and Baber, 1956, p. 6). The Warren gold placer district, described in detail by Reed (1937), is underlain in the northwest by Pre- cambrian gneiss, quartzite, and schist. Elsewhere the rocks are mainly epidote—bearing biotite—muscovite- quartz monzonite and related rocks of the Idaho batho- lith. Biotite—sillimanite—garnet gneiss and muscovitic or dense quartzite are the most common metamorphic rocks. At their contacts with the batholithic rocks, they are widely impregnated with granitic material and one rock grades into another. Unconsolidated sediments of several ages and origins occupy large parts of the Warren district. They include Tertiary gravel, pre-Wisconsin gravel, Wisconsin glacial mor- aine, and Recent alluvium. There are placer gravels in bench, hillside, and high-meadow deposits, and in the Recent alluvium there are meadow and gulch deposits. The bench, hillside, and gulch deposits have been large- ly worked out for gold, and most of the meadow de- posits have also been mined. W. H. Hill (1951, p. 14) estimated, however, that there are 40 million cubic yards of tailings 10—35 feet deep that have been left from gold mining in the 1930’s and 1940’s but that are rich enough in monazite to be dredged as monazite placers. IDAHO According to Reed (1937, p. 31—33), the concentrates from the various auriferous sedimentary materials in the Warren district are mineralogically similar. In Reed’s estimated order of decreasing abundance, the most abundant minerals are monazite, garnet, magne- tite, and zircon. Common minerals are limonite, gold, and epodite, and uncommon minerals are corundum, rutile, apatite, and xenotime. Scarce minerals are tour- maline, hornblende, pyrite, uraninite, and sillimanite. Inasmuch as only nine concentrates were examined by Reed, he cautioned that the estimated order of abun- dance may not be significant regionally for the uncom- mon and scarce minerals. The abundant and common accessory minerals are a voluminous part of the sand-sized fraction of the allu- vium in the Warren area; within a few hours of the commencement of a placer operation following a clean- up, the riflies filled with heavy minerals, and the recov- ery of gold was impaired (Reed, 1937, p. 30). Much of the heavy sand, about 45 percent according to W. H. Hill (1951, p. 14) and as much as 50 percent in a few samples according to Reed, was monazite. The monazite grains were said to be whole individual crys- tals with roughened faces and rounded edges (Reed, 1937, p. 32). They are smaller than many of the other heavy minerals. Most grains will pass through a 28- mesh sieve but will be retained on a 300-mesh sieve. Ordinary riffie sand screened to 20-mesh on a gold dredge in Warren Meadows, but not otherwise concen- trated, was analyzed by R. C. Wells and found to con- tain 1.7 percent of Th02, and sand passing a 60-mesh sieve contained about 2.8 percent of Th02. Thus, the monazite content of the Warren Meadows heavy sand can be significantly upgraded merely by sieving. An analysis of monazite from Warren Meadows made by the U.S. Bureau of Mines showed 3.96 percent of ThOz and 0.17 percent of U308 (Kaufl'man and Baber, 1956, p. 6), and an analysis by the U.S. Geo- logical Survey indicated 3.7 percent of Th02 and 0.16 percent of U308 (Gottfried and others, 1959, p. 21). VALLEY COUNTY Detrital monazite was first reported in Valley Coun- ty at Lardo (table 43) by Day and Richards (1906b, p. 1196—1197), but it was not until the late 1940’s and early 1950’s that any was mined. In 1949 a plant was constructed at McCall to separate monazite, i1- menite, magnetite, and garnet from black sands re— covered during gold mining (Staley and Browning, 1949, p. 2; Mining Cong. J our., 1949; Eng. and Mining J our., 1949). Only the monazite was marketed; the 151 other minerals were stockpiled. Beginning in 1950 several monazite deposits were explored by the U.S. Bureau of Mines, and by January 1951 private in- terests had begun to produce monazite by dredging Big Creek in the Cascade or Long Valley placer district (Lamb 1955a; Eilertsen and Lamb, 1956, p. 25). Production continued on Big Creek until Aug- ust 1955. During 1954 construction was started by Porter Brothers, Inc., on a dredge in monazite-euxe- nite placers in the Bear Valley area about 30 miles southeast of the Cascade district (Crawford, 1958a, p. 1158). Byproduct monazite was produced there from June 1956 until at least 1958 (Crawford, 1958b, p. 1125; Lewis, 1959, p. 1). Commercial monazite from the Cascade or Long Valley district was said by Kremers (1958, p. 2) to contain 63 percent of RE203 and 3 percent of Th02. The most northerly of the monazite placer deposits in Valley County is at Squaw Meadows just across the county line from the placers on Secesh Creek. Ex- ploration was conducted by the U.S. Bureau of Mines at Squaw Meadows during the early 1950’s. The Cascade or Long Valley placer district in Val- ley County was said to be the largest monazite placer district in Idaho (Staley, 1952, p. 309-310). It in- cludes several monazite-bearing eastern tributaries to the North Fork of the Payette River near Cascade. The North Fork rises in the Fayette Lakes north of McCall and flows southward through a conspicuous depression, formed by late Tertiary and Pleistocene faulting, known as Long Valley (Kline and Carlson, 1954, p. 10; Mackin and Schmidt, 1956, p. 376). As described by J. H. Mackin (Kline and Carlson, 1954, p. 10) Long Valley is a basin 40 miles long and 2—8 miles wide bordered by high mountains which rise steeply on the west and less precipitously on the east. The floor of the valley is covered by a thick sequence of monazite-bearing alluvium, possibly in part lacus- trine, brought in during at least two periods of deposi- tion by streams flowing mainly westward off the gran- itic rocks of the Idaho batholith. Sediments formed in the fault trough during the earlier of the two pe- riods of deposition were tilted westward by later faulting and are exposed along the east side of Long Valley. In the western part of the valley the earlier deposited alluvium was buried under the thick later formed sequence of sediments. Thus, the valley fill consists of a composite wedge of monazite-bearing sedi- ment that thickens westward and may be as much as several thousand feet thick in the western part of Long 152 Valley. The tenors of the deep parts of these sedi- ments are not known. The North Fork of the Payette River flows along the west side of Long Valley, and its eastern tribu- taries reach it by crossing the alluvium of the valley floor. Between the Payette Lakes and Donnelly only trace amounts of monazite have been found in the bed of the North Fork, and the stream gravel was said to consist principally of fragments of metamor- phic rocks distinctly different in provenance from the granitic gravel in the monazite-rich eastern trib- utaries to the North Fork in the Cascade district south of Donnelly (Kline and Carlson, 1954, p. 10; Hub- bard, 1955, fig.). West of Donnelly in an area around West Moun- tain where granitic rocks of the Idaho batholith are exposed on the west side of Long Valley, monazite was reported to occur in placer deposits, which were ex- plored by the U.S. Bureau of Mines in the early 1950’s (Eilertsen and Lamb, 1956, p. 11). About 4 miles south of Donnelly the Gold Fork en- ters the North Fork of the Payette River from the east. The stream is underlain by granitic rocks of the Idaho batholith. The Gold Fork was explored for monazite in 1951 by the U.S. Bureau of Mines and the U.S. Bureau of Reclamation. Although a report of the preliminary work was never published (Eilertsen and Lamb, 1956, p. 11), the placer was reexamined for ilmenite and other black-sand minerals in 1956, and a summary of the combined results of exploration in 1951 and 1956 was presented by Storch (1958a). These studies showed that Gold Fork occupies a nar- row valley except for a reach about 6 miles long up- stream from its confluence with the North Fork. There the valley floor is 1,000—4,000 feet wide, being widest at its downstream end, and Gold Fork, is entrenched 10—50 feet in gravel deposits. Parts of this area are covered by the impounded waters of the Cascade Res- ervoir. Thirty—one holes were drilled in the wide part of the Gold Fork valley to depths that ranged from 16 to 140 feet. Only three holes reached bed- rock. The distribution of black sand was found to be erratic, but the greatest amount was generally along the south side of the present channel of Gold Fork. A wide variety of minerals are present, as shown by the complete mineralogical analyses of concentrates from four holes (table 45). Ilmenite is the dominant mineral and is followed in abundance by garnet, magnetite, and sphene. The suite is little weathered, and the ilmenite is not en.- THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 45 —Mineralogical composition, in percent, of black sands from the Gold Fork placer, Valley County, Idaho [Modified from Storch (1958, p. 14). Symbols used: SA, small amount; -_, absent] Drill holes G-13 GF—3 GF—IO GF—ll Ilmenite _______________ 45. 7 55 48 40 Garnet ______ _ _____ 27. 4 21 18 15 Magnetite-_ __ _____ 1. 9 2 24 26 Sphene ________________ 5. 7 7 3 3 Quartz _________________ 8. 0 SA SA SA Epidote ________________ 3. 2 Trace 1 Trace Kyanite _______________ l. 4 _ _ _ _ _ _ Ferromagnesian minerals- 1. 7 Trace Trace Trace Zircon _________________ 1. 1 1 1 Monazite ______________ 2. 0 2 1 1 Xenotime ______________ . 3 _ _ Trace Trace Allanite ________________ Trace Trace Trace Trace Rutile _________________ _ .. Trace Trace <. 5 Topaz _________________ _ _ Trace Trace Trace Columbite- _ _ Trace _ _ _ _ Feldspar- _ _ _ _ Trace Trace Trace Apatite ________________ _ _ _ _ Trace Trace Radioactive opaque minerals _____________ _ _ Trace Trace Trace riched in titanium oxides. Monazite, a minor compo- nent of the concentrates from Gold Fork, was shown to contain 4.84 percent of ThO2 and 0.18 percent of U303 (Kauffman and Baber, 1956, p. 6). The weighted tenor in monazite in 44 composite samples of sediments from the drill holes was reported by Storch (1958a, p. 9). Weighted tenor, in'pounds per cubic yard, of composite samples fromtdrill holes in the valley of Gold Fork Minimum Maximum Average of 44 samples Monazite _________________ Trace 0. 81 0. 37 Ilmenite __________________ 1. 37 26. 20 9. 27 Magnetite _____________ _ Trace 20. 25 4. 69 Garnet ________________ w . 65 11. 54 2. 91 Zircon ___________________ Trace . 68 . 27 The Beaver Creek placer area is in the north end of the Cascade Valley in the Long Valley placer dis- trict (Storch and Robertson, 1954, p. 6). The placers extend about 4 miles northward along East Fork Creek and Beaver Creek, which are eastern tributaries to the North Fork of the Payette River and which drain from areas underlain by granitic rocks at the western edge of the Idaho batholith. During 1952 the U.S. Bureau of Mines drilled 16 holes in flood-plain deposits along East Fork Creek and Beaver Creek and estimated the monazite content of the sediments. IDAHO Tenor, in pounds per cubic yard, of stream deposits from East Fork and Beaver Creeks Minimum Maximum Average of 16 samples Monazite__________l _____ 0.1 0.54 0. 28 Ilmenite _________________ 2. 53 27. 39 9. 91 Magnetite ________________ . 07 1. 57 . 58 Garnet ___________________ Trace . 24 . 04 Zircon ___________________ . 21 . 06 Monazite from the Beaver Creek placer was an- alyzed by the U.S. Bureau of Mines and found to contain 3.82 percent of Th02 and 0.35 percent of U308 (Storch and Robertson, 1954, p. 13). The Beaver Creek placer area is not an economic source for mona— zite. The Big Creek area is in the Long Valley district near Cascade. It consists of placers on parts of Big Creek, including Scott Valley and the adjacent Horse— thief Creek, and deposits on Pearsol, Corral, and Clear Creeks. Scott Valley and Horsethief Creek are about 7 miles east of Cascade. Scott Valley is a high mountain basin drained by Big Creek. It is about 5 miles long, 300— 3,000 feet wide, and is carved in granitic rocks that form part of the west side of the Idaho batholith. Horsethief Creek is a tributary to Big Creek. The placer on Horsethief Creek lies half a mile south of Scott Valley. It is a basin about 6,000 feet long, as much as 2,000 feet wide, and occupies about one-fourth as much area as Scott Valley. Scott Valley and the Horsethief Creek basin seem to be in structural depressions controlled by faults. On its west side Scott Valley is bordered by fine- grained hard granite very resistant to weathering and on its east side it is bordered by soft, easily weathered coarse-grained granite. Renewed action along the faults was thought by Kline, Carlson, and Storch (1951a, p. 9) to have intermittently and partly sealed off Big Creek and Horsethief Creek with the result that lakes were formed and thick sequences of sedi- ments were deposited in them. These lacustrine sedi- ments consist of clay, sand, and fine—grained gravel derived from the granite. They were sampled by the U.S. Bureau of Mines in 1950 when 16 holes were drilled in Scott Valley and three were drilled in the Horsethief Creek basin (Kline and others, 1951a, p. 4). The holes in Scott Valley ranged in depth from 5 to 68 feet and those in the Horsethief basin, from 10 to 59 feet. 238—811 3—67 —1 1' 153 Heavy minerals in the sediments at Scott Valley and Horsethief Creek basin were found to be concentrated above layers of clay which served as false bedrock. The following mineralogical composition of composite concentrates from the two placer areas was analyzed by the U.S. Bureau of Mines: Mineralogical composition, in percent, of composite concentrates from Scott Valley and H orsethief Creek, Valley County, Idaho [Modified from analyses by U.S. Bur. Mines (Kline and others, 1951a, p. 10)] Scott Valley Horsethief Creek Ilmenite ________________________________ 73. 0 50. 9 Quartz _________________________________ 11. 0 20. 9 Garnet _________________________________ 5. 0 3. 0 Monazite _______________________________ 3. 8 11. 5 Zircon __________________________________ 1 8 . 8 Xenotime _______________________________ . 2 . 2 Epidote ________________________________ <. 1 2. 1 Rutile ________________________________________ 2. 6 Magnetite ______________________________ <. 1 2. 0 Pyrite ________________________________________ 3. 0 Amphibole, pyroxene, mica _______________ . 8 1. 5 Opaque minerals _________________________ The few holes in the Horsethief Creek basin indicate that this placer may be somewhat richer in monazite and leaner in total heavy minerals than the Scott Valley deposit (Kline and others, 1951a, p. 17). Tenor, in pounds per cubic yard, of deposits in Scott Valley and Horsethief Creek basin Scott Valley Horsethief Creek basin Mini- Maxi- Average Mini- Maxi- Average mum mum of 15 mum mum of 3 samples 1 samples Monazite .............. 0.21 l. 60 0. 83 0. 61 1. 68 1. 30 Ilmenite ________________ 2. 15 15. 67 9. 53 1. 37 3. 75 2. 65 Magnetite .............. . l7 6. 80 1. 01 . 15 . 42 . 31 G t . 47 4.15 1. 90 . 09 . 47 . 28 Zircon __________________ . 38 1. 33 . 65 . 08 . 55 . 32 1 Calculation of tenor of one hole not included in original report. The results of analyses by the U.S. Bureau of Mines showed an average of 4.11 percent of ThOZ and 0.17 percent of U308 for three samples of monazite from Scott Valley and 4.74 percent of Th02 and 0.10 percent of U308 in one sample of monazite from the Horse- thief Creek basin (Kline and others, 1951a, p. 19). The Scott Valley and Horsethief Creek deposits appar- ently were not mined during the early 1950’s when monazite was recovered from placers farther down- stream where Big Creek flows across Long Valley. Big Creek emerges from Scott Valley in a steep, narrow drop where it cuts its way for about 2 miles through granitic mountains to enter the east side of 154 Long Valley. The stream flows across Long Valley to its confluence with the North Fork of the Payette River. Where Big Creek crosses Long Valley the stream has formed a monazite—bearing meander plain 1,200—2,5OO feet wide which is bordered by sand and gravel benches 10—20 feet high (Kline and others, 1951b, p. 5). This part of Big Creek was farmed and had no prior history of mining at the time it was explored for monazite in 1950 ‘by the US. Bureau of Mines. The gravel, sand, and silt underlying the Big Creek meander plain was explored with 39 holes ranging in depth from 30 to 110 feet. To the maximum depth drilled the sediments were found to be composed of granitic debris. The gravel is small; few fragments are larger than 3 inches across. Well-sorted pebble layers having particles mostly about a quarter of an inch in diameter and scant clay or silt contain the greatest concentrations of heavy minerals. Commonly these layers rest on false bedrock consisting of a bed of clay. Concentrations of heavy minerals were also found in the sediments under the low terraces on each side of the meander plain. The average mineralogical composition of the con- centrates was reported to be the following (Kline and others, 1951b, p. 10): Percent Ilmenite ___________________________________ 65. 4 Monazite __________________________________ 8. 0 Garnet ____________________________________ 6. 5 Zircon _____________________________________ 2. 5 Magnetite _________________________________ 1. 0 Pyroxene, amphibole, biotite _________________ 4. 5 Pyrite _____________________________________ . 3 Quartz, feldspar ____________________________ 11. 8 Analyses made by the US. Bureau of Mines on four samples of monazite from Big Creek were reported as follows (Kline, Carlson, and Storch, 1951b, p. 20): Percent T1102 U304 BCD—ll ____________________________ 4. 12 O. 139 14--.. _________________________ 4. 23 . 132 31 ____________________________ 4. l8 . 123 32 ____________________________ 4. 26 . 120 Average ____________________ 4. 19 . 13 Field estimates of the amount of monazite in the sediments from the 39 drill holes ranged from 0.23 to 3.37 pounds of monazite per cubic yard and averaged 1.68 pounds per cubic yard. The field estimates were stated by Kline and others (1951b, p. 17) to be less accurate than the laboratory estimates, which were used to calculate ore reserves. Seemingly, the field estimates of monazite are somewhat too great, but the difl’erence was not reported for all samples. In THE GEOLOGIC OCCURRENCE OF MONAZITE seven comparisons the field estimates were shown to be 10—40 percent higher than the laboratory estimates. Field estimates for other heavy minerals were re- ported by Kline and others (1951b, p. 17). Tenor, in pounds per cubic yard, of sediments from Big Creek [Based on field estimates] Minimum Maximum Average of 32 samples Ilmenite ________________________ 4. 16 27. 52 14. 08 Magnetite ______________________ Trace . 81 . 17 Garnet _________________________ . 16 3. 31 1. 58 Zircon __________________________ . 23 1. 52 . 66 The results of the exploration indicated that the area contains comparatively large volumes of minable monazite-bearing gravel (Kline and others, 1951b, p. 5; Cummins, 1952, p. 169; Hubbard, 1955, p. 55). In 1951, private companies commenced to dredge for monazite in the Big Creek meander plain in Long Valley, and the operation continued until August 1955 after which date contracts for the monazite could not be obtained and mining ceased (Eng. and Mining J our., 19500; Mining Eng, 1951; Kaufiman and Baber, 1956, p. 11; Crawford, 1958a, p. 1157 -1158). Estimates of the output have not been given. After the close of mining, the deposit was said to have yielded 80,000 short tons of ilmenite as a stockpiled byproduct and to contain a reserve of 400,000 short tons of ilmenite (Kauffman and Baber, 1956, p. 9). If the field esti— mate cited above for the average tenor in monazite is reduced somewhat to accomodate the indicated overestimate and is called 1.4 pounds of monazite per cubic yard and if this is compared to the field estimate of the average tenor in ilmenite (about 14 pounds per cubic yard), then the inference can be made that the Big Creek placer may have produced about 8,000 short tons of monazite and has reserves of perhaps 40,000 short tons of monazite. Probable low recovery of monazite compared to ilmenite may somewhat reduce this estimated output. Pearsol Creek is a small stream about 4 miles long that rises in the foothills immediately east of Long Valley. Monazite placers occur in the Long Valley part of Pearsol Creek north of and contiguous with the monazite deposits in the Long Valley part of Big Creek. The Pearsol Creek placers are about 11/2 miles south of the town of Cascade. A block of ground about 2 miles long from north to south and 11/2 miles wide in the Pearsol Creek placer area was explored with 65 holes drilled by the US. Bureau of Mines in 1951 (Kline and Carlson, 1954, p. 5). The geology of the deposit is virtually the same as that of the Big IDAHO Creek deposit, and the southern part of the Pearsol Creek placer nearest to Big Creek has the best tenor in monazite. Although minable tenors in monazite were detected to a depth as great as 120 feet in one hole, in most holes the best tenors were at depths of 15—55 feet. A composite concentrate from one drill hole in the Pearsol Creek placer was found to contain about one- tenth as much monazite as ihnenite (Kline and Carlson, 1954, p. 12): Percent Percent Ilmenite _____________ 80. 5 Garnet _______________ 1. 6 Altered ilmenite _______ 1. 0 Quartz _______________ 5. 9 Magnetite ____________ . 7 Zircon _______________ . 1 Epidote ______________ . 2 Xenotime ____________ . 1 Pyroxene, amphibole, Monazite _____________ 8. 4 biotite _____________ . 2 Minor amounts of allanite and radioactive opaque minerals are present in concentrates from the Pearsol Creek placer. Inclusions of a fergusonitelike mineral were observed in some grains of monazite, and a small amount of very fine grained gold was found in a few concentrates. The tenors of the sediments in about one-third of the southern part of the Pearsol Creek placer are similar to those in the Big Creek deposit, elsewhere they are less, and in the north half of the area magnetite makes up 10—30 percent of the concentrate (Kline and Carl- son, 1954, p. 11, 18, 19). Sediments sampled in the 65 drill holes contained 1.94—69.01 pounds of concentrates per cubic yard with an average of 14.7 pounds per cubic yard. Monazite made up 1.4—18.3 percent of the concentrate and averaged 6.9 percent by field estimate. Somewhat less monazite was indicated by the results of laboratory examination: by chemical analysis the range was 16—127 percent, with an average of 6.3 per— cent, and by radiometric analysis the range was from 2.0 to 12.8 percent, with an average of 6.7 percent. The tenor determined by chemical analysis was the most accurate. The richest part of the Pearsol Creek placer was said by Kline and Carlson (1954, p. 8) to be along the east side of Long Valley just north of the Big Creek deposit. Monazite from the Pearsol Creek placer was analyzed by the US. Bureau of Mines and found to contain 4.4 percent of ThOZ and 0.2 percent of U308 (Kline and Carlson, 1954, p. 21—22). Corral Creek is about 2 miles south of the Big Creek placer area and 5 miles southeast of Cascade, Valley County. The stream is 4 miles long and flows west- ward into Long Valley from the foothills to the east. A north-trending area 2 miles long and 11/; miles wide along the part of Corral Creek in Long Valley was 155 drilled for monazite in 1951 by the US. Bureau of Mines (Kline and others, 1955, p. 5). Sixty-one holes from 20 to 123 feet deep were sunk. Samples of allu- vium contained from 0.29 to 14.94 pounds of concen- trate per cubic yard and averaged 6.33 pounds. By field estimate from 4.2 to 38.3 percent of the concen- trate was monazite, the average being 20.5 percent (Kline and others, 1955, p. 16—20). Somewhat less monazite was indicated by laboratory analyses of sam- ples from 59 out of the 61 holes, of which the chemical determinations were regarded by the Bureau as the more accurate: the range was from 4.2 to 33.9 percent with an average of 18.7 percent by chemical analysis and from 4.8 to 38.2 percent with an average of 18.6 percent by radiometric determinations. The following mineralogical composition, in percent, of concentrates from three drill holes in the Corral Creek placer area was reported (Kline and others, 1955, p. 11): 00-6 00—16 00-50 Monazite _______________________ 22. 5 19. 6 34. 2 Magnetite ______________________ 1. 4 8. 2 . 2 Ilmenite ________________________ 59. 6 60. 1 60. 0 Garnet _________________________ Trace Trace Trace Zircon _________________________ 1. 0 . 5 Epidote ________________________ . 8 . 4 ________ Xenotime _____________________ . . 1 Trace Euxenite, samarskite- Trace ________________ Quartz _________________________ 12. 5 9. 0 4. 5 Pyroxene, amphibole, biotite ______ . 3 . 4 ________ Monazite from the Corral Creek placer area was ana- lyzed by the US. Bureau of Mines and found to con- tain 4.39 percent Th0; and 0.10 percent U308 (Kline and others, 1955, p. 18). Geologically the Corral Creek placer resembles the Big Creek placer. The central one-third of the area drilled, which is on the Big Creek side of Corral Creek, was said to be the richest part of the deposit (Kline and others, 1955, p. 7). Clear Creek crosses Long Valley from the east about 8 miles southeast of Cascade. The stream was explored for monazite in the early 1950’s by the U.S. Bureau of Mines (Eilertsen and Lamb, 1956, p. 11). Monazite from the Clear Creek placer was said to contain 4.13 percent Th02 and 0.12 percent U308 (Kauffman and Baber, 1956, p. 6). The Stolle Meadows, a mountain valley on the South Fork of the Salmon River, are about 20 miles north- east of, and outside of, the Cascade or Long Valley placer district. They were explored for monazite dur- ing the early 1950’s by the US. Bureau of Mines (Eilertsen and Lamb, 1956, p.11; Kaufl'man and 156 Baber, 1956, p. 7). Similarly, Peace Valley on a tribu— tary to the Middle Fork of the Payette River, about 15 miles southeast of, and outside of, the Cascade or Long Valley placer district, was explored for monazite by the Bureau in the early 1950’s (Eilertsen and Lamb, 1956, p. 11). A. large valley on the Deadwood River, a northern tributary to the South Fork of the Fayette River in the south-central part of the Idaho batholith in Valley County, was drilled by the US. Bureau of Mines in 1956 and appraised as having no economic value as a source for monazite or ilmenite (Storch, 1958b, p. 9). Ten holes ranging in depth from 6 to 40 feet were sunk, and samples showed that the sediments contained less than 0.1 pound of monazite and only 3.3 pounds of ilmenite per cubic yard. The Deadwood River deposit in Valley County is 8 miles long and about 1,000 feet wide, locally expand- ing in width to more than 3,000 feet. It is floored with glacial deposits and alluvium on granite. Only the downstream one-third of the length of the valley was explored. None of the drill holes reached bedrock; hence, the thickness of the fill is not known. Appar- ently an early sequence of sediments was deposited in the valley and later disturbed by glacial erosion. The present sequence of sediments has virtually the same concentration of heavy minerals as the rocks of the valley walls. Field estimates of the five main heavy minerals were reported by Storch (1958b, p. 9). Weighted tenor, in pounds per cubic yard, of concentrates from 10 drill holes in the Deadwood River deposit Minimum Maximum Arithmetic average Monazite _________________ Trace 0. 28 0. 08 Ilmenite __________________ 0. 43 10. 78 3. 28 Magnetite ________________ . 36 13. 55 4. 57 Garnet ___________________ . 08 1. 57 . 20 Zircon ___________________ . 03 . 20 . 09 The complete mineralogical composition of concen- trates from four drill holes in the Deadwood River alluvium is given in table 46. A few miles east of the monazite occurrence at Dead- wood River, several headwater tributaries to the Mid- dle Fork of the Salmon River in Valley County were reported to be monazite bearing. Elk Creek and the White Hawk basin were explored for monazite by the US. Bureau of Mines (Kaufiman and Baber, 1956, p. 7). . A very large monazite-euxenite placer was, discov— ered by the US. Bureau of Mines on Bear Valley Creek in Valley County during exploration between 1950 and 1952, and dredging of the deposit was begun THE GEOLOGI'C OCCURRENCE OF MONAZITE TABLE 46fMineralogicol composition, in percent, of concentrates fIrém}: drill holes in Deadwood River alluvium, Valley County, a o [Modified from analyses by US. Bur. Mines (in Storch, 1958, p. 13). Symbols used: SA, small amount; __, absent] DW—l DW—2 DW—5 DW—9 Ilmenite _______________ 34. 0 10. 0 14. 0 33. O Magnetite ______________ 49. O 74. 0 61. 0 22. O Garnet ________________ SA SA _ _ SA Titaniferous magnetite__ 3. 0 3. 0 4 0 3. 0 Sphene ________________ . 5 1. 0 __ 5. 0 Ferromagnesian SA SA 3. 0 Trace minerals. Gahnite ________________ Trace _ _ - _ _ _ Rutile _________________ <. 5 <. 5 Trace <. 5 Ilmenorutile ____________ Trace Trace Trace _ _ Zircon _________________ . 5 . <. 5 2. 0 Epidote ________________ _ _ Trace Trace Trace Hematite ______________ Trace Trace Trace Trace Allanite ________________ Trace Trace Trace SA Apatite ________________ Trace Trace Trace <. 5 Pyrite _________________ Trace Trace Trace Trace Xenotime ______________ Trace Trace Trace Trace Cyrtolite _______________ _ _ - _ Trace - _ Columbite _____________ _ 1 _ _ Trace Trace Monazite ______________ Trace <. 5 <. 5 <. 5 Radioactive opaque minerals ______________ Trace <. 5 Trace Trace by Porter Brothers Corp. in 1955 and continued after other Idaho placers closed; thorium, uranium, and niobium—tantalum minerals were recovered (Hubbard, 1955, p. 55). Specific statements about reserves at the Bear Valley placer have not been released, but the com- bined reserves of it and deposits in the Victor and McCalla area, Montana, were reported to be 244,140 short tons of monazite, 1,660 short tons of uranotho- rite, 7,500 short tons of euxenite, 1,876,230 short tons of ilmenite, and 51,280 short tons of zircon in 485 mil- lion cubic yards of alluvium (Eilertsen and Lamb. 1956, p. 10). Bear Valley Creek is a northward- and northeast- ward-flowing main headwater tributary to the Middle Fork of the Salmon River in Valley County. Placer depOsits along the stream include three contiguous areas known, from south to north, as Upper Bear Val- ley or the Big Meadows area, which occupies about 3 miles in the southern part of the valley; the Central Bear Valley area, which extends for 11 miles down- stream from Big Meadows; and the Lower Bear Val- ley area, which includes the widest downstream part of the valley (Kline and others, 1953, p. 6). Bear Val- ley Creek is in the south—central part of the Idaho batholith. The valley was extensively glaciated during at least two episodes of glaciation, and the present valley fill has resulted from glacial derangement of drainage in late Pleistocene time (Mackin and Schmidt, 1956, p. 376—378; 1957, p. 4). Glacial boul- ders as much as several feet in diameter occur along the sides of the Upper and Central Bear Valley Creek, IDAHO and terminal and lateral moraines as much as several hundred feet high are present. Most of the alluvial deposits consists of fine to coarse sand and small pebbles. TheBear Valley Creek placer was explored between 1950 and 1952 by the US. Bureau of Mines with 42 holes in the Upper Bear Valley or Big Meadows area, 25 holes in the Central Bear Valley area, and 16 holes in the Lower Bear Valley area (Kline and others, 1953, p. 5, 14—19). Several kinds of radioactive minerals were found. The most common are monazite and eux- enite, but samarskite, fergusonite, xenotime, allanite, sphene, and zircon are also present. The composition of concentrates from composited samples from two drill holes in the Big Meadows area was reported to be as follows: Percent B—I'I 13-36 Ilmenite _______________________________ 40. 2 58. 6 Magnetite _____________________________ 34. 7 10. 3 Garnet ________________________________ 16. 2 20. 0 Quartz ________________________________ 2. 6 1. 0 Sphene ________________________________ . 5 1. 0 Epidote _______________________________ Trace 5 Pyroxene, amphibole, biotite _____________ . 6 4 Pyrite _________________________________ Trace _______ Rutile _________________________________ . 1 . 46 Zircon _________________________________ Trace . 07 Monazite ______________________________ 3. 5 3. 6 Radioactive opaque minerals _____________ . 01—. 05 . 14—. 3 Two samples of monazite from the Bear Valley Creek placer were found to have the following average percentages of thorium oxide and uranium oxide: [Analyst: U.S. Bureau of Mines (in Kline and others, 1953, p. 20)] Percent '—’I‘_hOz U303 1 __________________________________ 4. 37 0. 28 2 __________________________________ 4 82 . 27 Average ______________________ 4. 60 0. 27 157 This abundance of thorium oxide is 0.9 percent less than that ascribed by Kremers (1958, p. 2) to com- mercial concentrates from the placer. The range in tenor of the sediments in the three parts of the Bear Valley Creek placer are shown in table 47. Tenors decrease downstream. The upper part of Bear Valley Creek, the area known as Big Meadows, has the highest tenors in the radioactive heavy minerals. The relation of the tenor of the sediments to geolog- ic processes has been discussed by Mackin and Schmidt (1956, p. 378—379; 1957, p. 4). They showed that allu- vium deposited by small streams entering Big Mead- ows from nonglaciated areas in an early Wisconsin glacial stage and outwash and morainal deposits formed there by early Wisconsin glaciers average 30 and 20 pounds of heavy minerals per cubic yard, re- spectively, whereas morainal and outwash deposits from late Wisconsin glaciers in Big Meadows average 10 pounds of heavy minerals per cubic yard. This dif- ference was attributed to the release of heavy minerals from the crystalline rock by deep weathering during pre-Wisconsin time, making them available for trans- port and concentration in early Wisconsin time. The early Wisconsin glaciers scoured away the weathered mantle. Residual concentrations of heavy minerals in a weathered mantle were not available for late Wiscon- sin glaciers; hence, the tenor of their deposits is low. Selective transportation and dilution were also shown by Mackin and Schmidt to be involved in the down- stream decrease in tenor in Bear Valley Creek. In an aggrading stream like Bear Valley Creek the heavy minerals lag behind and are buried under light min- erals because the streambed is not subject to continuous reworking. Dilution of a particular placer mineral in the concentrate is caused by the discharge of low- TABLE 47.—-Range in tenor, in pounds per cubic yard, of the main black sand minerals in the Bear Valley Creek placer, Valley County, Idaho Analyses from Kline, Carlson, Storch, and Robertson (1953, p. 5, 14—19). garnet, and zircon calculated from field estimates. Monazite, euxenite, and columbite calculated from petrographic analyses. Magnetite, ilmenite, Symbol used: n.d., no data] Bear Valley Upper Central Lower Minimum Maximum Average (42 Minimum Maximum Average (25 Minimum Maximum Average (15 samples) samples) samples) Monazitel ______________________________ 0. 12 1. 98 0. 62 0. O2 1. 36 0. 31 0 0. 18 0. 07 Euxenitel _______________________________ 0 . 98 . 19 0 . 32 . 09 O . 05 n.d. Columbitel _____________________________ O . 75 . 12 0 . 16 . O6 0 . 06 n.d. Magnetite2 _____________________________ . 18 17. 06 3. 45 . 20 10. 13 3. 52 n.d. n.d. n.d. Ilmenite2 _______________________________ 2. 40 29. 52 12. 76 2. 73 12. 92 6. 39 n.d. n.d. n.d. Garnet? ________________________________ 1. 02 14. 66 7. 48 . 17 a 61 1. 41 n.d. n.d. n.d. Zircon2 _________________________________ O . .50 . 05 0 . 17 . 03 n.d. n.d. n.d. 1 Calculated from petrographic analyses. 2 Calculated from field estimates. 158 tenor sediments from downstream tributaries which drain unfavorable bedrock sources. Output of mona- zite from the Bear Valley Creek placer is not known. ADAMS, FAYETTE, AND GEM COUNTIES Adams County has been cited several times for oc- currences of detrital monazite after Day (1905b, p. 19) reported that 123 pounds of monazite was found in a short ton of auriferous concentrate from Meadows. This and another monazite-bearing concentrate from Meadows were subsequently listed by Day and Rich- ards (1906b, p. 1200—1201) and are described in table 43. Monazite has also been reported from the Snake River (Schrader and others, 1917, p. 119; DeMent and Dake, 1948, p. 15; Dake, 1955, p. 56) and from a local— ity northwest of Meadows near the county line west of Granite Lake, Valley County (Hubbard, 1955, fig). Further data on these localities are lacking. Fayette County was said to have placer monazite (Day, 1905a, p. 9), but there is some confusion about the location of the occurrence. Probably this refer- ence and the report by Day and Richards (1906b, p. 1196—1197) refer to an occurrence along the Payette River in Fayette County (Schrader and others, 1917, p. 119). The composition of one concentrate from this doubtful locality is shown in table 43. Johnson Creek in Gem County was mentioned by Eilertsen and Lamb (1956, p. 12) as a monazite placer area explored by the US. Bureau of Mines in the early 1950’s. BOISE COUNTY The Boise basin in Boise County is the discovery locality of monazite in Idaho. About 1896 Waldemar Lindgren of the US. Geological Survey identified monazite among the minerals in concentrates from gold placers along Moore Creek, Granite Creek, and Wolf Creek near Placerville, and in lake beds near Idaho City (Lindgren, 1897, p. 63; 1898, p. 677 ; Tur- ner, H. W., 1902, p. 343). He observed that the grains of quartz and heavy minerals in the placers were angular and sharp edged, a characteristic that he inter- preted to result from the rapid removal and accumula- tion of the sand from deeply disintegrated surfaces of adjacent granite masses. After Lindgren’s discovery of detrital monazite in the Boise basin placers, work by the US. Geological Survey in 1905 (Day and Rich- ards, 1906b, p. 1196—1197) on the mineralogical com- position of monazite-bearing samples from Placerville, Centerville, Grimes Creek, and Idaho City showed that sediment and concentrates from the gold placers in the Boise basin contained from a trace to 358 pounds THE GEOLOGIC OCCURRENCE OF MONAZITE of monazite per short ton (table 43) and that the area had commercial concentrations of monazite (Pratt, 1906, p. 1313). ' The Boise basin occupies a small marginal part of the Idaho batholith. The rocks exposed in the basin are principally granite, quartz monzonite, granodio- rite, and diorite, which are intruded by porphyry, lamprophyre, and pegmatite and which are overlain by lake beds and lava flows (Ballard, 1924, p. 18—20; Kline and others, 1950, p. 7—15). Metasedimentary rocks into which the batholith was intruded are not exposed in the basin; thus, an unknown thickness of metamorphic and igneous rocks were eroded to expose the granite. Lake beds formed of partly consolidated clay and fine sand of probable Miocene age occupy the low parts of the basin, and they are covered by flows of basaltic and rhyolitic lava. The lake beds exceed 600 feet in thickness and seem to have no workable concentrations of gold or monazite, although monazite is present in them. In Quaternary time several suc- cessions of gravel were deposited on the lava and lake beds. These sediments, which have a complex geolog- ic history and physiographic expression, are the com- mercial source of the gold and monazite. The earliest attempts to mine placer monazite in Idaho were said to have been made on Grimes Creek and Granite Creek near Centerville in the Boise basin. There is some confusion among the various accounts of the enterprise, but apparently about 1903 the Cen- terville Mining and Milling Co., owning placer ground on these streams, began to experiment with ways to recover a monazite separate from the concentrates pro- duced at the gold placers. In 1906 the company con- structed a plant and separated 2 or 3 short tons of monazite but did not ship the product. The plant was enlarged in 1907 and 1909, and small quantities of monazite were produced but were not marketed. Dur- ing 1910 the plant was destroyed by forest fire and was not rebuilt. When the plant was destroyed the records were lost, and no authentic production figures have survived (Metall. and Chem. Eng, 1910; Salt Lake Mining Rev., 1910; Mining Sci., 1910; Sterrett, 1911, p. 901; Jones, E. L., 1916, p. 97; Pratt, 1916, p. 62; Shannon, 1926, p. 411; Staley and Browning, 1949, p. 2; Kline and others, 1950, p. 24; Kaufl'man and Baber, 1956, p. 3). Against this probable record is the seem- ingly erroneous report by Santmyers (1930, p. 14) that this enterprise was a factor in the monazite industry of the United States from 1903 through 1910. A renewal of commercial interest in the monazite of Idaho, and particularly of the Boise basin, took place IDAHO in 1922 (Campbell, Stewart, 1922, p. 28) and 1938 (Mining J our. [Phoenix], 1938), but no monazite was produced and, during the mid-1920’s, the Centerville placers were regarded as an uneconomic source for thorium minerals (Ballard, 1924, p. 33). In 1941 and 1948 the possible commercial importance of the placer monazite in Boise County was again being pointed out (Campbell, Arthur, 1941, p. 5; Mining Cong. J0ur., 1948, p. 70). Commercial recovery of monazite in the Boise basin was undertaken in a small way in 1946 and continued as a minor byproduct venture of gold mining until 1948 at the Baumhoff-Marshall dredge near Cen- terville and the Idaho-Canadian dredge near Idaho City. During this time a part of the jig concentrate from these dredges was pumped ashore and stockpiled. Some of the concentrate was trucked to McCall for the separation of monazite. Through 1948 this opera- tion produced 40 short tons of monazite (Kline and others, 1950, p. 24). In October 1948 the U.S. Bureau of Mines did some preliminary surface sampling for monazite in the Boise basin. Between August and November 1949 the Bureau, under the auspices of the U.S. Atomic Energy Commission, drilled the placers. This program showed that the greatest reserves of monazite were in the enormous volume of tailings from early gold mining on Moore Creek, Granite Creek, Grimes Creek, and Elk Creek. Considerable reserves of monazite were also found in unmined placers on tributaries to Granite Creek, mainly Wolf Creek, Fall Creek, and Canyon Creek, and also on Moore Creek (Kline and others, 1950, p. 5, 35). Black sand from the different gold placer areas in the Boise basin was found by the U.S. Bureau of Mines to range in weight from 2.71 to 8.84 pounds per cubic yard of gravel and to contain from 7 to 13 per- cent of monazite (table 48). The monazite separate produced at the old Center- ville plant in the early 1900’s was described in company statements as consisting of 95 percent of monazite and containing 5—5.2 percent of Th02 (Salt Lake Mining TABLE 48. ~—Pr1'nc1§pal heavy minerals in percent, of concentrates from gold placers in the Boise basin, Boise County, Idaho [Modified from Kline, Carlson, and Griffith (1950, p. 17). Based on field estimate] Granite Wolf Grimes Elk Creek- Grass Flat Creek Creek Creek Moore Flats Creek Creek Concentrate, lb per cu yd. 8. 13 7. 45 4. 78 2. 71 4. 32 8. 84 Monazite ________________ 12 11 13 7 8 7 Ilmenite ______ .-_ 37 42 38 17 40 27 Magn etite. . . 27 16 26 3 39 54 Garnet ................... 9 8 10 54 3 4 Zircon ____________________ 15 23 13 19 10 8 159 Rev., 1910; Sterrett, 1911, p. 902); however, two analyses of monazite concentrates of unknown purity from the Centerville area, made by W. F. Hillebrand in 1906, disclosed 4.42 and 4.60 percent of Th02 and the mean of five analyses made by R. C. Wells in 1911 showed 3.01 percent of Th02 (Sterrett, 1911, p. 902— 903). Analyses of four samples of relatively pure monazite from the Boise basin showed the following percentages of thorium and uranium oxides: [Analystz U.S. Bureau of Mines in 1949 (in Kline and others, 1950, p. 32)] Percent Th0: UaOs l ____________________________ 2. 98 0. 100 2 ____________________________ 3. 06 . 105 3 ____________________________ 2. 9 No data 4 ____________________________ 4. 0 No data Average ________________ 3. 2 0. 1 Impure monazite concentrates from dredges near Idaho City and Centerville, Boise basin, were reported by Staley (1952, p. 308), and a sample of pure mona- zite from the Boise basin was reported by Staley and Browning (1949, p. 5). Chemical analyses, in percent, of monazite from Boise basin Vicinity of Near Center- Boise basin Idaho City ville RE203 ___________________ 34. 2 62. 3 66. 8 1. 6 1. 9 2. 2 4. 3 2 7 26. 7 9. 0 3 8 . 7 . 6 . 6 Ca, Al, and Fe oxides __________________________ 1. 6 Five samples of pure monazite from placers in the Boise basin near Idaho City and Placerville were re- ported by J afi'e, Gottfried, Waring, and Worthing (1959, p. 95) to have alpha activity between 2,634 and 3,241 alpha particles per milligram per hour, indica- ting only moderate abundances of thorium oxide in the monazite. Some exploration was conducted by the U.S. Bureau of Mines on the Rabbit Creek placer near Idaho City, Boise County, but a description of the monazite occur- rence has not been published (Eilertsen and Lamb, 1956, p. 12). Monazite from Rabbit Creek was anal- yzed by the Bureau and was found to contain 5.50 per- cent of ThOz and 0.36 percent U308 (Kauffman and Baber, 1956, p. 6). Elsewhere in the area the Lakow Flats placer was said to have monazite but is not a commercial source (Armstrong, 1953, p. 217) ; the Summit Flats placer was examined for monazite by 160 the US. Bureau of Mines, but an evaluation of the deposit has not been published (Kauttman and Baber, 1956, p. 7). Porter Creek west of Quartzburg was said to ‘be monazite bearing (Hubbard, 1955, fig.). A few miles north of the northwestern part of the Boise basin, monazite was reported (Day and Rich- ards, 1906b, p. 1196-4197) from the North Fork of the Fayette River at Garden Valley (table 43), Boise County. In the same area monazite was also reported from the North Fork of the Fayette River at Banks (Hubbard, 1955, fig). ADA, OWYHEE, ELMORE, AND CUSTER COUNTIES Ada County was mentioned in the early 1900’s as a source for detrital monazite (Day, 1905b, p. 21; Day and Richards, 1906a, p. 152; 1906b, p. 1194—1195). Two concentrates from around Boise contained more than 200 pounds of monazite per short ton (table 43), but apparently none of the occurrences is an exploitable deposit. Dry Creek, north of Boise, was explored for monazite in the early 1950’s by the US. Bureau of Mines. Oreana in Owyhee County was the source of a mon- azite-bearing concentrate (table 43) described by Day and Richards (1906b, p. 1200—1201) and subsequently cited frequently (Sanford and Stone, 1914, p. 67; Hill, J. M., 1915, p. 282—283; Schrader, Stone, and Sanford, 1917, p. 119; DeMent and Dake, 1948, p. 15; Dake, 1955, p. 56). Monazite was also reported in the allu- vium along Jordan Creek near DeLamar and along a tributary to Rabbit Creek south of Murphy, Owyhee County (Hubbard, 1955, fig). The Dismal Swamp placer is at the headwaters of Buck Creek about 8 miles northwest of Rocky Bar, Elmore County. Sampling of the deposit in 1952 and 1953 by private interests, the US. Geological Survey, and the US. Bureau of Mines showed that it contained niobium-, tantalum—, and uranium-bearing minerals and a small amount of monazite but that the deposit was probably not large enough to be exploited (Armstrong, 1953, p. 217; 1957a, p. 386; Shelton and Stickney, 1955, p. 3). According to Armstrong (1957a, p. 385~388), the placer is in a narrow valley near the south end of the Idaho batholith at a point about midway between the east and west margins of the batholith. Glaciation during late Wisconsin time did not affect the Dismal Swamp area; hence, the granodiorite underlying the deposit is weathered to gruss for a depth of at least 2 feet. Alluvium consists of products derived by local stream erosion and slope wash from the weathered surface of the granodiorite. A concentrate from the deposit was reported to have THE GEOLOGIC OCCURRENCE OF MONAZITE the following composition (Shelton and Stickney, 1955, p. 3): Weight percent Columbite ________________________________ 67. 47 Samarskite ________________________________ 6. 14 Zircon ____________________________________ 5. 58 Ilmenite __________________________________ 5. 12 Garnet ___________________________________ 3. 7O Monazite _________________________________ 3. 49 Quartz and feldspar ________________________ 8. 50 Total ______________________________ 100. 00 Other minerals noted in concentrates from the Dismal Swamp placer are anatase, cassiterite, cyrtolite, mag— netite, rutile, titaniferous magnetite, topaz, and xeno- time (Armstrong, 1957a, p. 386). Allanite was said to be a common accessory mineral in the rocks of this region (Anderson, 1943, p. 5, 8; Smith and others, 1957, p. 372), but it was unreported in the concentrates, possibly owing to weathering. The minerals seem to be original constituents of the granodiorite and small pegmatite dikes that cut the granodiorite. The monazite was said by Shelton and Stickney (1955, p. 3) to contain 50.8 percent total REzOg plus ThOz, 1.4 percent szOs, and less than 1 percent Ta205. Either there is some error in this analysis or the material analyzed was not pure monazite, because the abundance assigned to the RE203 plus Th02 is 10—15 percent too low. The tenor of the gravel in the placer was reported to be 1.40—1.87 pounds per cubic yard of weakly mag- netic minerals containing 14—20 percent Nb205 + TazOs, but the actual amount of monazite was not stated (Armstrong, 1957 a, p. 390~392). It seems to be small. Alexander Flats on the Middle Fork of the Boise River, Elmore County, was the source of detrital mon- azite analyzed by the US. Bureau of Mines and found to contain 5.98 percent T1102 and 0.18 percent U308 (Kauffman and Baber, 1956, p. 6). Placer monazite has been found near the extreme south end of the exposed part of the Idaho batholith at Mud Flats in Elmore County. Monazite from the placer was found by the US. Bureau of Mines to con— tain an unusually large amount of thorium oxide for monazite from the Idaho batholith: 6.24 percent of Th02 and 0.22 percent U308 (Kauffman and Baber, 1956, p. 6). Custer County was said to have occurrences of detri- tal monazite at Valley Creek, Meadow Creek, Stanley Creek, Kelly Creek, Yankee Fork Gold Creek, Wil- liams Creek, and Pigtail Creek (Eilertsen and Lamb, 1956, p. 11—12; Savage, 1960, fig. 1). None of these monazite deposits has been described in detail, but it IDAHO was stated that the notable gold placers along Stanley Creek and Yankee Fork gave only slight indications of monazite (Staley, 1952, p. 305). Except for Yankee Fork and Pigtail Creek, these monazite occurrences were examined by the U.S. Bureau of Mines in the early 1950’s (Eilertsen and Lamb, 1956, p. 11—12), and monazite from Valley Creek was determined to have 3.31 percent Th02 and 0.18 percent U308 (Kauifman and Baber, 1956, p. 6). Allanite was said to be a com- mon accessory mineral in the granitic rocks in the Stanley Creek area (Smith and others, 1957, p. 372), but its concentration in the placers is doubtful. LEMBI, CAMAS, AND BLAINE COUNTIES Concentrates from Arnett Creek, Wards Gulch, and unnamed streams, probably including Moose Creek (Hubbard, 1955, fig), in the Leesburg Basin gold placer district, Lemhi County, were shown by Day (1905b, p. 20) to contain from 0.5 to 10 pounds of monazite per short ton. Day and Richards (1906b, p. 1198—1199) observed as much as 44 pounds of monazite per short ton of concentrate from the Leesburg Basin (table 43). Monazite was said to be sulficiently con~ centrated in a placer near the junction of Smith Gulch and Napias Creek in the Leesburg area that it could be recovered in a gold-dredging operation (Shockey, 1957, p. 36). The general tenor of the auriferous sed- iments in the Leesburg district, however, was too low for the economic recovery of monazite (Staley, 1952, p. 305). Gold placers on tributaries to the Lemhi River between Salmon and Tendoy and at Gibbonsville on the North Fork of the Salmon River in Lemhi County have been described as having very sparse monazite (Staley, 1952, p. 305; Savage, 1960, fig. 1). Minor amounts of monazite have been found in the alluvium of streams tributary to the Salmon River between the towns of Shoup and North Fork in northern Lemhi County where low-thorium oxide monazite forms seg- regations in marble (Abbott, 1954, p. 5). The Camp Creek placer area is an irregularly shaped tract about 0.5 mile wide and 3.25 miles long that extends southeasterly down Camp Creek where that stream is crossed by the line between Camas County and Blaine County (Robertson and Storch, 1955a, p. 7). The northern part of the placer is in Camas County and the southern part is in Blaine County. Granodiorite and quartz monzonite of the Idaho batholith are exposed near the placer, but in the northeastern part of the Camp Creek basin these rocks are covered with basaltic flows. During 1954 the deposit was drilled by the U.S. Bureau of Mines and found to contain appreciable magnetite, ilmenite, 238—813—67—12 161 sphene, hornblende, uranothorite, and several sparse minerals among which was monazite (table 49). TABLE 49.——Mineralogical composition, in percent, of concentrates 5207;: the Camp Creek placer, Camas and Blaine Counties, a 0 [Analyst: U.S. Bur. of Mines (in Robertson mad Storch, 1955, p. 12). Symbol used: -_, a sen Test pit Drill hole CC—l TC—l TC—2 Epidote __________________ 1—2 1—2 2. 5—3. 5 Pyroxene, hornblende, and other minerals __________ 1—2 2 3-4 Garnet ___________________ <0. 2 <0. 2 <0. 2 Ilmenite __________________ 9—11 26-30 26—38 Magnetite ________________ 68-72 29—33 15—17 Monazite _________________ . 01 . 1 . 1 Pyrite ___________________ Trace Trace Trace Quartz ___________________ 9—1 1 16-20 13—15 Zircon ___________________ <1 . 5—. 8 2—3 S hene ___________________ 4‘5 10—12 16—18 ranothorite _____________ . 3 1. 2 2. 0 Colored opaque minerals--- . 5 4~5 3—4 Black opaque minerals ----- . 5 <1 <1 Rutile ___________________ Trace - _ Trace Gold _____________________ Trace -- -_ Although the volume of the deposit is large, the pla- cer is not a significant source for monazite. Monazite was found by the U.S. Bureau of Mines in 1954 to be present in trace amounts in the alluvium of Rock Creek, Blaine County (Robertson and Storch, 1955b, p. 11—12). The drainage basin of the stream is underlain by granite and lava flows, and the heavy minerals in the Rock Creek placer resemble those in Camp Creek: dominant magnetite, sphene, hematite, hornblende, biotite, epidote, pyroxene, and allanite, and minor ilmenite, zircon, garnet, cyrtolite, colum- bite, thorite or uranothorite, and a trace of monazite. LINCOLN, MINIDOKA, BANNOCK, AND BINGHAM COUNTIES Black sand from Shoshone, Lincoln County, was reported by Day (1905b, p. 22) and Day and Rich- ards (1906a, p. 153; 1906b, p. 1198-1199) to contain 26 pounds of monazite per short ton of concentrate (table 43), but the source of the concentrate was not specifically identified. It may have been from the Wood River, which leads to the Camp Creek and Rock Creek placers, where a little monazite has been found. A concentrate from the Snake River near Minidoka, Minidoka County, was reported by Day and Richards (1906b, 1). 11984199) and J. M. Hill (1915, p. 282— 283) to contain 8 pounds of monazite per short ton (table 43). Detrital monazite . apparently occurs in Bannock County, but the locality was not given (Day, 1905a, p. 9). 162 Sand from the Snake River in Bingham County was said by Day and Richards (1906b, p. 1194—1195) and J. M. Hill (1915, p. 282—283) to have a trace of monazite (table 43). ILLINOIS mes DOME PRIMARY MONAZITE A remarkable occurrence of yttrium—rich monazite at Hicks Dome, Hardin County, was described by Trace (1960). He noted that Hicks Dome is a tee- tonic feature which has been previously described as an incipient cryptovolcanic structure. The dome covers about 100 square miles in western Hardin County and affects sedimentary rocks of Devonian, Mississip- pian, and Pennsylvanian age. At the center of the dome in an area comprising about 2 square miles, limestone, chert, and black shale of Devonian age attain dips as great as 15° and are accompanied by a few tabular to pipelike masses of breccia and an altered mafic dike. The breccia zones in this central area are anomalously radioactive. They also contain more beryllium, rare earths, niobium, and zirconium than the unbrecciated rocks. The radioactive mineral in the breccia zones at the center of Hicks Dome was identified by Trace (1960, p. B63) as monazite. The monazite occurs with flo- rencite, a cerium-aluminum phosphate, and fluorite in very fine-grained carbonate matrix between fragments of limestone, chert, and black shale in the breccia, but it has not been found in the sedimentary rocks. Con— tacts between the fragments of sedimentary rock in the breccia and the matrix are sharp, and the frag- ments of sedimentary rocks are apparently unaltered. The monazite forms small, soft, earthy rounded to subrounded brownish-yellow grains about 0.004~0.01 inch in diameter. Preliminary study by X—ray diffrac— tion demonstrated that the mineral has the monazite cell structure but that the size of the cell is small. A quantitative spectrochemical analysis showed that the monazite is unusually rich in the yttrium earths and lean in the cerium earths and that it has the following composition: [Analystz H. J. Rose, Jr. (in Trace, 1960, p. B60] Percent Percent 06203 ________________ 16 P 205 _________________ 29 Lagos ________________ 1 l Si02 _________________ 4. 4 Nd203 _______________ 6 A1203 ________________ 2. 2 8111203 _______________ 2 F6203 ________________ 6. 6 Gd203 _______________ 1. 5 Ti02 _________________ 2. 7 PI'203 ________________ 2. 5 030 _________________ 3. 8 DyZ03 _______________ 1. 5 MgO ________________ . 2 Y203__‘ _______________ 4. 2 ThOZ ________________ 4. 4 Total __________ 98 THE GEOLOGIC OCCURRENCE OF MONAZITE The unusually great amount of yttrium was re- garded by Trace as possibly accounting for the small cell size of the monazite. Trace also noted that the relatively low content of cerium and lanthanum and great amount of yttrium in the monazite resembles the composition of relatively unfractionated, or primi- tive, monazite as described by Murata, Rose, and Car- ron (1953, p. 296—297) and by Murata, Rose, Carron, and Glass (1957, p. 148—150). The percentage of thorium oxide in this monazite, 4.4 percent, is re- markably high for monazite in carbonate rocks. The observations that the monazite occurs in a cryptovolcanic structural feature, that it is relatively unfractionated, and that it has an unusually large amount of thorium oxide for monazite in a calcareous environment are here interpreted to mean that the monazite formed with little fractionation at depth and was transported with explosive rapidity toward the surface. Rapid upward transport prevented reactions that would have lead to lower abundances of thorium and yttrium in the monazite or possible total elimina- tion of a monazite phase. The monazite from Hicks Dome is the only known occurrence of monazite in a cryptovolcanic structural feature. DETRITAL SOURCES Very minor amounts of detrital monazite are pres- ent among the accessory heavy minerals in sand of Cretaceous age exposed in southern Illinois south- west of Hicks Dome. Monazite was reported in three samples of sand from the vicinity of Boaz, Massac County; single samples near Karnak and Olmsted, Pulaski County; and two samples near Sandusky, Alexander County. The composition of the monazite- bearing suites of heavy minerals from the sand is shown in table 50. Resistate minerals from metamor- phic rocks such as kyanite, staurolite, and sillimanite together with resistate minerals of igneous or meta- morphic origin like rutile, tourmaline, zircon, and ilmenite accompany the monazite in the Cretaceous sedimentary rocks. Xenotime is also present in very small amounts. Only 1 out of the 18 samples from glacial outwash examined by Lamar and Grim contained minor acces- sory monazite (table 50). It came from the West Chicago area in McHenry County. Unstable minerals of dominantly igneous and metamorphic origin like augite, diopside, hypersthene, hornblende, and garnet accompany the monazite, and the stable, dominantly metamorphic minerals common in the Cretaceous sand of southern Illinois, are missing from the outwash. Two river sands of the nine samples of Recent lake and river sand were found to have minor amounts of ILLINOIS, INDIANA, IOWA, KENTUCKY, MISSOURI, LOUISIANA TABLE 50.——Mineralogical composition of monazite—bearing suites of heavy minerals from alluvium of Recent age, glacial outwash gravel of Wisconsin age, and sand of Cretaceous age in Illinois [Modified from Lamar and Grim (1937, p. 80—81). Symbols used: A, abundant; C, common; R, rare; VR, very rare; Ab, absent] 1 2 3 4 5 6 7 8 9 10 R A Ab Ab Ab Ab Ab Ab Ab R 0 Ab Ab Ab Ab Ab Ab Ab R C VB V R VR Ab VR Ab Ab A A Ab Ab Ab Ab Ab Ab Ab Hornblende ...... A VR A Ab Ab Ab Ab Ab Ab Ab Hypersthene _____ R C 0 Ab Ab Ab Ab Ab Ab Ab Ilmenite _________ Ab R Ab C C R C V R C C Kyanite .___ VR A Ab A A A A C A A R Ab C R R C VB C C R A Ab VR VR R R R VB VB V R V R VR VB VB VB VB. VB C Ab C A A A A C A 0 Ab C C C C C C C R Ab C R R Ab VR R R C Ab A C A C C C C C Ab C C C A C A A VR Ab VB. VB Ab V R VR V R Ab C Ab A A A A A A A Recent river sand: 1. Mississippi River sand near Gladstone, Henderson County. Contains abun- dant chlorlte, rare biotite and enstatite, and very rare wollastonite. 2. Ohio River near Olmsted, Pulaski County. Contains common chlorite. Glacial outwash gravel of Wisconsin age: 3. West Chicago, McHenry County. Sand of Cretaceous age: 4—6. Near Boaz, Massac County. Sample 6 contains very rare andalusite. 7—8. Near Sandusky, Alexander County. 9. Near Olmsted, Pulaski County. 10. Near Karnak, Pulaski County; monazite (table 50). One was from the Mississippi River near Gladstone in Henderson County, and the other was from the Ohio River near Olmsted, Pulaski County, where the shore of the river is faced by blufls of Cretaceous sand which contains a small amount of monazite. The river sands contain stable and unstable minerals including species present in both the Cretace- ous and Wisconsin sediments. Two concentrates from the bed of the Mississippi River at Cairo, Alexander County, just downstream from the monazite-bearing Cretaceous sediments, were examined by Russell (1937, p. 1319) and found to contain less than 1 percent of monazite. INDIANA Black sand of unspecified origin from the vicinity of Michigan City, La Porte County, was found by Day and Richards (1906b, p. 1200—1201) to contain 34 pounds of monazite and a small amount of gold per short ton of concentrate: Pounds per short ton Magnetite _________________________________ 1, 181 Chromite __________________________________ 2 Garnet ____________________________________ 370 Monazite __________________________________ 34 Zircon _____________________________________ 66 Quartz ____________________________________ 344 Total ________________________________ 1, 997 Possibly the material was sand from the shore of Lake Michigan. 163 IOWA Heavy-mineral suites from samples of loess and till of Pleistocene age from several localities in Iowa were examined by P. T. Miller and the results compiled by Kay and Graham (1943, p. 182). All samples of Peorian Loess and Iowan till were found to be mona- zite bearing (table 51). The till contained three times as much monazite as the loess, but even in the richest samples the monazite only amounted to 0.52 percent of the total heavy minerals. Five samples of monazite-bearing sediments were taken from two local- ities, North Liberty in Johnson County and West Union in Fayette County. A trace of monazite was observed by J. W. Whitlow (oral commun., 1956), US. Geological Survey, in the fine sand discarded at a sand and gravel-washing plant just north of Bellevue, Jackson County. Gravel is derived from glacial till. Garnet is abundant and magnetite, zircon, and gold in small amounts are also present. ImNTUCKY AND MISSOURI Recent bottom sediments of the Mississippi River at Hickman, Fulton County, Ky., contain sparse mona- zite. Concentrates from five samples of sediment from the Kentucky and Missouri sides of the river had monazite, but in each sample the monazite- made up less than 1 percent of the concentrate (Russell, 1937, p. 1318). LOUISIANA Monazite is a scarce component of concentrates made from sand of Pleistocene and Recent age in Louisiana. Two out of five samples of sand of Pleis- tocene age were found by E. P. Thomas (Woodward and Guano, 1941, p. 9—10) to contain about 2 percent of heavy minerals among which monazite was a minor accessory (table 52). One concentrate was from an exposure of the Williana Formation near Fullerton in Vernon Parish, and the other was from the Prairie For- mation at Merryville in Beauregard Parish. Monazite rarely constitutes as much as 2 percent of the heavy minerals separated from sediments in the present bed of the Mississippi River in Louisiana (Russell, 1937, p. 1330). At Angola, West Feliciana Parish, all four of the concentrates contained mona- zite. In three concentrates monazite was less than 1 percent of the concentrate, and in one it was 1 percent. At Baton Rouge, East Baton Rouge Parish, monazite was present as less than 1 percent of the concentrate in two concentrates and as 1 percent in one concen- trate. All 21 concentrates from sediment in the pres- ent channel of the Mississippi River at New Orleans, Orleans Parish, contained monazite. In 16 concen- 164 THE GEOLOGIC OCCURRENCE OF MONAZITE TABLE 51—Mineralogical composition, in percent, of monazite—bearing suites of heavy minerals from Pleistocene loess and fill in Iowa [Modified from analyses by P. T. Miller (in Kay and Graham, 1943, p. 182). Symbol used: .-, absent] Peorian Loess Iowan till Except North Kansan till Liberty and North West Union All Iowa Except West West Union All Iowa West Union Liberty cut out Union cut out cuts Pyrite __________________________ 7. 92 1. 33 2. 01 4. 05 6 60 1. 65 3 30 2 55 Magnetite and ilmenite ___________ 19. 2O 13. 78 19. 15 17. 69 10 58 20. 20 16 99 11 12 Hornblende ______________________ 27. 32 36. 29 29. 37 30. 76 43 30 32. 03 35 69 38 14 Pargasite ________________________ . 62 1. 24 1. 98 1. 02 1 10 1. 76 1 51 1 09 Glaucophane ____________________ . 32 1. 48 1. 81 1. 06 55 1. 85 1 48 42 Actinolite _______________________ . 50 1. 73 . 73 1. 29 1 07 . 61 76 78 Tremolite _______________________ . 11 . 75 . 55 . 52 -_ __ __ 1 09 Hypersthene _____________________ 1. 13 1. 46 2. 73 1. 34 2 75 1. 66 2. 02 1 81 Enstatite ________________________ . 57 1. 52 . 63 1. 18 1 08 . 24 . 52 1. 33 Augite __________________________ 2. 29 12. O2 25. O9 6. 95 30 1. 92 3. 05 3. 45 Aegerite-augite ___________________ . 11 . 02 . 23 . 09 __ . 36 . 24 . 54 Aegerite _________________________ . 27 . 35 . 36 . 32 . 07 . 16 . 13 54 Chlorite _________________________ 3. 56 1. 21 . 12 2. 05 . 80 . 18 . 39 1 57 Andalusite ______________________ . 34 1. 35 . 92 . 99 . 34 . 95 . 75 __ Epidote _________________________ 6. 35 10. 35 5. 02 8. 08 10. 55 3. 3O 5. 72 7. 51 Zircon __________________________ 4. 35 3. 13 7. 26 4. 38 3. 27 9. 26 7. 26 5. 55 Garnet __________________________ 5. 80 5. 51 8. 07 6. 30 7. 48 10. 18 9. 26 15. 22 Tourmaline ______________________ . 49 1. 81 2. 89 1. 51 . 88 1. 72 1. 44 . 49 Sphene __________________________ . 99 . 82 1. 90 . 89 29 1. 71 1. 24 . 78 Biotite __________________________ 15. 71 . 76 2. 36 6. 66 63 2. 14 1. 64 3. 77 Stanrolite _______________________ . 30 . 95 . 54 . 70 69 1. 09 . 96 __ Topaz __________ , ________________ . 44 . 21 2. 96 . 29 19 1. 77 1. 24 . 18 Kyanite _________________________ . 30 . 34 __ . 33 75 __ . 08 . 73 Rutile __________________________ __ 38 1. 35 25 71 . 37 . 48 . 73 Brookite ________________________ _- __ .12 __ .10 .13 . 12 __ Barite __________________________ . 11 . 99 __ 68 13 __ . 05 01 Monazite ________________________ . 16 . 08 32 11 27 . 39 . 35 12 Riebeckite _______________________ . 08 . 07 10 07 15 . 52 . 40 -_ Basaltic hornblende ______________ . 46 . O7 60 21 28 1. 71 1. 23 54 Spine] __________________________ __ __ .68 -_ __ .36 .24 _- Anthophyllite ____________________ . 08 __ 28 03 . O2 . 54 . 37 95 Hedenbergite ____________________ _ _ _ _ 17 _ _ __ . 24 _ _ - - Other minerals ___________________ . 18 . 08 -- 12 92 1. 21 1 11 -_ TABLE 52,-—Mi7}emlogical 097711008111?” of concentrates from two cent in three concentrates and 2 percent in two con- nwnazzte-bearing sand units of Pleistocene age ’I/I’L Louiswna centrates. At Profit Island, Plaquemines Parish, tWO [Modified from analyses by E. P. Thomas (Woodward and Gueno, 1941, p. 10). No , _ qganttiltative range of abundance given in original report. Symbol used: Ab, concentrates contained 2 percent of monaZIte, three had a sen 1 percent, and seven had less than 1 percent. Prairie William Out of 16 concentrates from sand and silt in the Formation Formatlon . . . . . . M1ss1ss1pp1 Delta, 7 contain sparse monamte (table Magnetite __________________________ MA MA 53). Among the monazite-bearing sediments repre- Ilinemte ---------------------------- VA VA sented in the samples are Recent dune sand from Cat Zircon ______________________________ A A , Leucoxene __________________________ C C Island and subsurface sand and s11t from Freemason (Srgilrgggne ------------------------- E 8 Island and Chandeleur Island, St. Bernard Parish, Kyanite- I::::::::::::::::::::::::: R C subsurface and Recent surface sand from Southeast £33251}; ------------------------- 5R 5R Pass, and subsurface and bottom samples from North Diopside ____________________________ VR Ab Barataria Bay, Plaquemines Parish. Spodumene _________________________ VR Ab Epidote _____________________________ gfi XR MAINE 11 't _____________________________ b . . . Moflzae ___________________________ VR R The occurrence of monaz1te 1n the crystalllne rocks, Limonifie ———————————————————————————— Ab C principally pegmatite, of Maine was mentioned at Hematite ___________________________ Ab C . . Couophane______________. ___________ Ab R least as early as 1891 (Derby, 1891a, p. 205; Mining 12:33:23? (blue'green) -------------- 2% y}: and Sci. Press, 1902) in surveys of the distribution of _________________________ the mineral in the United States, but primary or sec- ondary deposits of economic importance have not been trates the monazite was less than 1 percent of the con- found. The known primary deposits are mostly local- centrate. The monazite reached abundances of 1 per- ities where monazite can only be obtained in specimen MAINE AND MARYLAND TABLE 53.—Mineralogical composition, in frequency percent, of monazite-bearing concentrates from sediments in the Mississip i Delta in St. Bernard and Plaquemines Parishes, La., and at Island, Harrison County, Miss. [Modified from Dohm (1936, p. 378-379). Symbols usedtzlP, present; R, rare; VR, very rare; TL, trace; __, absen 1 2 3 4 5 6 7 Magnetite 1 ................... 0. 3 6 3 1. 3 Tr. 1.9 0.1 2.7 Ilmenite (traces of chromite) 26 10 4 7 20 4 29 Leucoxene ........... .. 5 3 6 2 8 9 ._ 3 2 7 9 2 13 __ P 1 R _- P 2 _ . 6 P 4 1 2 3 ._ 12 6 11 11 12 5 __ VB VB _- __ __ ._ _ . _ _ 5 _ _ _ . _ . _ __ VR 19 R R R P __ ._ 13 P __ R 2 _. 14 4 15 12 15 1 -_ VR __ R __ _. Hypersthene . _ 2 R P 2 1 P Homblende: Common ........................ . _ 7 3 7 4 10 1 Blue-green - _ 10 3 7 6 6 3 Basal ............... _. P 2 1 2 R Actinolite and tremohte. . .. 5 4 11 4 7 P Apatite .............. _ _ 3 P P 1 1 R Zircon. _ 61 4 2 2 4 R 9 Sphene- _ . 2 P 3 1 3 R Rutile. _ 8 VB VB R P __ 4 Monazit 1 R VB VB P VR R Staurolite. R VR _ . R ._ . _ 6 Sillimanite_. ______ _ ._ P VR R R R R Kyanite ............ __ 2 VB VB P R R 6 Chloritoid ___________________________ _ . VR -_ VR ._ .. ._ Tourmaline: Brown or yellow to greenish brown or black ___________ _. VB VB R P 2 Brown or yellow to olive gree _ . VR . _ VR ._ _. .. Colorless to yellow or brown _____ __ R __ R .. VR R Garnet: Colorless ......................... R 4 P 5 8 4 P Brown ........... _ . _ VR .. ._ R - . Pink toa ricot__.. _ ._ ._ VR 3 P R Dolomite an siderite.. ._ R 11 P 12 6 1 __ Cellophane .......................... _ _ P R VR 1 R R 1 Magnetite removed by magnet and expressed as weight percent of the concentrate. Abundances of the other minerals are expressed as frequency percent 01 the magnetite- free concentrate. . Extremely well sorted dune sand from Cat Island, Harrison County, Miss. . Fairly well sorted fine sand taken at 8 feet below surface in a boring on the north end of Freemason Islands just east of Neptune Point. . . Fairly well sorted silt taken at 18 feet below surface in a boring on the Windward side of Chandeleur Island group east of lower Freemason Islands. . Well-sorted very fine grained sand taken at 17 feet below surface in a boring in the natural levee of Southeast Pass. . Extremely well sorted Mississippi River sand of Recent age taken from the surface of a mudlump at the mouth 0 Southeast Pass. . Fairly well sorted very fine sand taken at 13.5 feet below surface in a boring on the south edge of a small island 1.5 miles to the southeast of St. Marys Point in North Barataria Bay. 7. Well-sorted sand from bottom 0.5 mile to the southeast of sample 6. Gall‘hNNi-l quantity. Whatever placer deposits may have been formed in pre-Pleistocene- time were eroded by the continental glaciation, and sizable placers have not been formed since the last glaciation. Monazite occurrences in pegmatite in the Topsham feldspar district have been most often described in the literature. The district is about 1 mile wide and 8 miles long and extends north-northeastward from Top- sham to Bowdoinham, Sagadahoc County (Shainin, 1948, p. 5; Cameron and others, 1954, p. 5). High- grade metamorphic rocks of dominantly sedimentary origin underlie the area. They include coarse-grained biotite gneiss, biotite-hornblende gneiss, hornblende gneiss, and quartz-andesine-diopside gneiss. Interlay- ered with the metasedimentary rocks are a variety of granitic gneisses, quartz-plagioclase aplite, and grani- tic pegmatite. Many of the masses of aplite cut across 165 the foliation of the metamorphic rocks, and the peg- matite cuts across all the other rocks. Late mafic dikes of probable Triassic age transect all other rocks in the Topsham area. Feldspar has been mined from or prospected for at many large openings and thousands of small pits, and in a very few of these places speci— mens of monazite have been found (Morrill, 1958, p. 50). Several pegmatite quarries immediately west of Top- sham at a locality known as Standpipe Hill have been the source of monazite crystals as much as 1 by 1% inches in size (Yedlin, L. N., 1942, p. 206). The crystals of monazite are euhedral twinned lustrous— brown grains. They tend to occur in microcline at the contact between the microcline and biotite and are in places associated with samarskite. Monazite from a pegmatite dike in the Topsham district had the following composition: [Analystz Edith Kroupa in 1936 (in Lane, 1937, p. 58; see also Rodgers, 1952, p. 421)| Percent Percent RE203 _____________ 40. 59 PbO _______________ 0. 181 Th0; ______________ 6. 70 MnO ______________ . 72 U303 _____________________ SO4 ________________ . 25 P205 _______________ 16. 21 Ego—(110°) ________ . 52 SiOz _______________ 13. 91 Loss on ignition A1203 ______________ . 63 (110°—1,000°)___- 3. 29 FeO _____________________ Insoluble residues- _ - 9. 78 F8203 ______________ 7. 21 CaO _______________ . 91 Total ________ 101. 31 MgO ______________ . 41 Monazite was questionably reported by Derby (1891a, p. 205; Twinem, 1932a, p. 31; 1932b, p. 31; Morrill, 1959, p. 58) to occur as a minor accessory mineral in gneiss at Blue Hill (East Blue Hill), Han- cock County. , Pegmatite near Auburn, Androscoggin County, was said to be monazite bearing (Twinem, 1932a, p. 31). MARYLAND Monazite was found by Dryden and Dryden (1946, p. 92—94) to be one of the minor accessory minerals in the Wissahickon Schist of northern Maryland, but specific occurrences were not listed. The heavy minerals in 10 samples of sedimentary rocks of Eocene age from southern Maryland were examined by Lincoln Dryden (1932, p. 518—519). Monazite was found to occur as scarce grains associ- ated with similarly sparse andalusite, corundum, to- paz, brookite, dumortierite, glaucophane, anatase, zoi- site, sphene, muscovite, chlorite, hypersthene( 3), and clinozoisite( 2). The principal minerals in concen- trates from the sedimentary rocks and their average order of abundances were zircon, 35 percent; stauro- lite, 30 percent; garnet and rutile, 8 percent each; epi- 166 dote, 7 percent; tourmaline, 6 percent; kyanite, 3 per- cent; chloritoid, 2 percent; and sillimanite, 1 percent. Localities of individual samples were not listed. Recent beach sand at Ocean City, Worcester County, contains a trace of monazite (Day and Richards, 1906b, p. 1202—1203): Pounds per short ton Ma gnetite _________________________________ Trace Ilmenite ___________________________________ 138 Garnet ____________________________________ 12 Olivine ____________________________________ Trace Monazite __________________________________ Trace Zircon _____________________________________ 19 Quartz ____________________________________ 1, 8 16 Unclassified ________________________________ 15 Total ________________________________ 2, 000 Also reported is about a hundredth of an ounce of gold per short ton of natural beach sand. MASSACHUSETTS South Orange in Franklin County was mentioned as early as 1852 as a monazite locality, but the nature of the occurrence was not specified (Shepard, 1852, p. 109). In 1891 monazite was reported from gneiss at Westford and Ayer, Middlesex County, and may have been observed at Milford and Dedham, Norfolk Coun- ty (Derby, 1891a, p. 205). A zone of rocks characterized by above-background amounts of radioactivity was described by D. H. J ohn- son (1951, p. 6—7) as extending northeastward from the northeast border of Connecticut to north—central Massachusetts. Abnormally radioactive formations in the zone are the Coys Hill Granite, Hubbardston Gra- nite, and Hardwick Granite of late Carboniferous or post-Carboniferous age, and the Brimfield Schist and Paxton Quartz Schist of Carboniferous age. Although the high radioactivity is fairly uniformly distributed throughout the zone, local biotite-rich pegmatitic lay- ers at Southbridge, Worchester County, and biotite— garnet gneiss and biotite schist exposed 3 miles south of Worchester, Worchester County, are especially radioactive. Thorium was reported to be the major source of the radioactivity, but specific thorium-bear- ing minerals were not cited by D. H. Johnson (1951, p. 11—14). Probably very little of the radioactivity comes from monazite. Indeed, monazite may not be present, because no nearby occurrences are known in Massachusetts or Connecticut. Possibly most of the thorium is present in intergranular films or in other THE GEOLOGIC OCCURRENCE OF MONAZITE minerals like biotite, epidote, and apatite (Keevil and others, 1944, p. 350). MICHIGAN Remarkable fossil monazite placers are preserved in the Palmer area, Marquette County (Vickers, 1953, p. 203—204; 1956a, p. 173—185; 1956b; McKelvey, 1955, p. 42; Davidson, 1957, p. 674). .The first indication of monazite was abnormal radioactivity observed by Robert Reed in 1951 to be associated with fragments of Goodrich Quartzite on mine dumps near Palmer. In 1952 R. C. Vickers of the US. Geological Survey examined the occurrences and determined that the radioactivity came from detrital monazite concen- trated in the quartzite. The following summary of the geology of the fossil placers is taken from Vickers (1956a, p. 173—185). The Palmer area is underlain by a downfaulted block of Precambrian sedimentary rocks 4 miles long and three-fourths mile wide on the south limb of the Marquette synclinorium. The fault block consists main- ly of middle Huronian Ajibik Quartzite and Negau- nee Iron-Formation and the unconformably overlying late Huronian Goodrich Quartzite.’ Monazite occurs as brownish-red to yellow sub- rounded to rounded detrital grains in the matrix of layers of quartz-pebble conglomerate in Goodrich Quartzite. Most grains are 0.40—0.08 inch across. Local- ly they make up more than 50 percent of the matrix of the conglomerate, but usually the grains are not that abundant. Other heavy minerals in the matrix are mainly hematite, magnetite, ilmenite, and rutile. In the lower 200 feet of the Goodrich Quartzite, the weighted average monazite content for 18 channel sam— ‘ ples was 2.9 pounds per short ton. An isolated out- crop of pebble conglomerate more than 300 feet above the base of the formation contained 23 pounds of monazite per short ton. Glacial boulders and frag- ments on mine dumps, derived from even higher parts of the formation, contained from 50 to 110 pounds of monazite per short ton. From these observations it was inferred that the tenor of the layers of pebble conglomerate was greater in the parts of the Good- rich Quartzite that were 300 feet or more above the base of the formation. This inference was confirmed by the gamma—ray logging of three diamond-drill holes that penetrated a maximum apparent thickness of 1,100 feet of quartzite. Two chemical analyses of monazite fractions, re- ported to contain about 92 percent of monazite, MASSACHUSETTS, MICHIGAN, MINNESOTA, MISSISSIPPI disclosed 7.6 and 7.4 percent of ThOz, equal to 8.2 percent of ThOz in pure monazite: [Analystz Harry Levine (in Vickers, 1956a, p. 180)] Percent A B RE203 _______________________________ 47. 9 46.0 T1102 ________________________________ 7. 6 7. 4 U0, ________________________________ .2 .2 P205 ________________________________ 19. 4 19. 3 s10 _________________________________ 6. 9 5. 7 A1253 ________________________________ 1 5—10 1 5—10 Fe203 ________________________________ 1 5—10 1 5—10 rio2 ________________________________ 1 1—5 1 1—5 PbO ________________ . x 1—5 11—5 Total __________________________ 94-112 91-109 1 Spectrographic analysis. The Palmer area contains very large tonnages of monazite that seem to have about 8 percent of Th02. At present there is no known deposit of equal high- thorium oxide monazite in the United States. Elsewhere in the area of the Marquette trough there seems to be very little monazite in the Goodrich Quartzite. A few grains of monazite, however, were observed by Vickers in Goodrich Quartzite exposed about 5 miles N. 75° W. of Palmer. Several concentrations of monazite occur in coarse arkosic quartzite that overlies and grades downward into a granite porphyry in the Gwinn district, Mar- quette County, 12 miles southeast of Palmer. Some of the quartzite contains as much as 9 pounds of mona- zite per short ton, but the concentrations are of only local extent (Vickers, 1956a, p. 185). The relation of the composition of the monazite to the metamorphic zones in the Marquette trough is not known. Seemingly, absence of exposures might pre‘ vent satisfactory study, but if samples of monazite could be obtained from quartzite at the difl'erent meta- morphic grades, a relation might be found between the grade of metamorphism, absolute abundance of mona- zite, and composition of monazite. It would be par— ticularly interesting to learn if detrital monazite in quartzite reacted to metamorphism the same way that detrital monazite in pelitic sediments seems to do. MINNES OTA Quartz monzonite at the Myers quarry near Pierz, Morrison County, contains accessory monazite (J affe and others, 1959, p. 138). Monazite also occurs in the Warman Quartz Monzonite of Woyski (1949) 7 miles west of Little Falls, Morrison County, where R. G. Schmidt (oral commun., 1960) recovered 200 milli- grams from 15 pounds of rock. Monazite has been mentioned as a very rare acces- sory mineral in sandstone units in the St. Laurence 167 Formation of Cambrian age exposed near Minneiska, Wabasha County (Graham, 1930, p. 710; Grim, 1936, p. 115—116). The abundances of thorium and radium in soil at 13 places in Minnesota were determined in 1915 by J. C. Sanderson (1915, p. 397). The soils sampled were de- veloped on boulder clay, till, drift, loess, dune sand, moraine sediment, and outwash deposits. Although the range in amount of thorium in the soils was not great, the variations were marked within the small range and were independent of the radium content. Mineral sources of the thorium radiation were not identified. Possibly the most important mineral source was allanite, which seems to be more common in the crystalline rocks of Minnesota than monazite (Winchell, 1900, p. 206, 212, 291; Sanders, 1929, p. 146). MISSISSIPPI SEDIMENTARY nocxs or EOCENE AGE Heavy minerals in the very fine sand fraction from about 50 samples of sedimentary rocks of the Wilcox, Claiborne, and Jackson Groups of Eocene age exposed in Mississippi were studied by Grim (1936, p. 23—26), and monazite was found to be a minor accessory min— eral. It was variably present in very fine sand from the Wilcox Group, present in about two-thirds of the samples from the Claiborne Group, and absent from the samples of the Jackson Group. The mineralogical composition of the 28 monazite-bearing concentrates from the Wilcox and Claiborne Groups is shown in table 54. Lateral and vertical variation in the major compo- nents of the concentrates were not very pronounced in the sand from the Wilcox Group (Grim, 1936, p. 108— 115), but there was considerable variation in the scarce minerals. Scarcity alone was interpreted to be suffi- cient cause for the variation. No consistent relation was found between the abundance of the heavy min- erals in the very fine sand fraction and the general coarseness or fineness of the sample from which the fraction was sieved. The uniformity in the major components was interpreted to indicate that a single source area supplied the Wilcox sediments. The dominant heavy minerals and most of the minor minerals are stable species derived originally from schist, gneiss, and granitic rocks. Minerals from mafic rocks are unimportant components of the concentrates. The absence of unstable minerals in the concentrates was interpreted by Grim to show that the sedimentary materials of the Wilcox Group had passed through more than one cycle of erosion, transportation, and deposition. 168 THE GEOLOGIC OCCURRENCE OF MONAZITE The presence of monazite and xenotime among the minor minerals in the Wilcox Group, together with the mineralogy of the dominant species in the concen- trate, indicated to Grim (1936, p. 115) that the most probable ultimate source of the sediment was the Pied- mont Plateau region of the southern Appalachians. Deposition of the sedimentary rocks of the Wilcox Group in Mississippi was inferred by Grim (1936, p. 116) to have taken place in a huge delta formed by a river flowing from the northeast and entering the em- bayment in northeast-central Mississippi. Variable conditions on the delta gave rise to local subaerial deposits and subaqueous deposits with more marine, near-shore deposits being formed toward the south- east away from the delta. The composition of the concentrates from the very TABLE 54.——Mineralogical composition of very fine monazite-bearing concentrates from sedimentary rocks of Eocene age in Mississippi [Modified from Grim (1936, p. 65-193). Symbols used: A, abundant; 0, common; R, rare; VR, very rare; Ab, absent] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Heavy mineral concentrate (very fine sand)--- percent_- 2. 74 3.50 2. 43 1. 53 2. 8 8.5 1 0 3. 5 1 7 1. 1 1. 1 5 3 3. 1 1 0 Ilmenite_-__--_-__----‘_--- Ab R R R C R C R R C C C C R Leucoxene ---------------- Ab R R R C VR R VR R Ab C C C R Rutile -------------------- R A R C C C R R C C C C C C Zircon -------------------- R A A C A C C C C A A A A C Garnet ------------------- Ab Ab Ab Ab Ab Ab VR Ab Ab Ab Ab Ab Ab VR Staurolite _________________ C R A C C C C C C A A A A C Andalusite ________________ Ab Ab Ab R Ab Ab Ab Ab VR Ab VR Ab Ab VR Kyanite __________________ C A A C A C C C C A A A A C Sillimanite ---------------- Ab R R R VR Ab VR Ab Ab VR Ab R Ab VR Monazite _________________ R R R R VR C VR VR VR VR VR R VR VR Xenotime ----------------- R R Ab R VR VR Ab Ab VR VR VR Ab VR Ab Epidote ------------------ R R R R Ab Ab Ab Ab Ab Ab Ab Ab VR R Tourmaline --------------- R R A C C C C C C A A C Other minerals ------------ (l 2) Ab (3) (1 4 5) (5) (7) Ab (3) (9) (1°) (11) Ab Ab Ab 15 16 17 18 19 2o 21 22 23 24 25 26 27 28 Heavy mineral concentrate (veryfinesand)_--percent-- 1.0 2 8 2 6 3 0 2 9 0 3 3 3 1,9 2.7 2 3 4 2 1. 1 2 1 2,8 Ilmenite __________________ R R R R VR R C R R C R C C C Leucoxene ---------------- R R R R Ab R C R R C R C C C Rutile ____________________ R C C C R R C C C C C C R C Zircon ____________________ C C C C C C A C C A C C A A Garnet ___________________ Ab Ab Ab Ab Ab Ab Ab Ab VR VR Ab VR VR Ab Staurolite _________________ C C C C C C A C C C C A C C Andalusite ________________ Ab R Ab Ab Ab Ab Ab VR Ab Ab VR Ab VR VR Kyanite __________________ C C C C C C A C C A C A A A Sillimanite ________________ C R R R Ab R A i R R VR R A A R Monazite _________________ R VR VR VR VR VR VR VR VR VR R VR VR R Kenotime ----------------- Ab VR VR Ab VR VR VR VR VR VR C VR VR VR Epidote __________________ Ab VR Ab VR Ab Ab VR Ab Ab VR VR VR Ab VR Tourmaline _______________ C C C C C C C C C C C C C C Other minerals ____________ (‘2) Ab Ab (9) (‘3) (11) (1‘) Ab Ab Ab Ab (1‘) Ab Ab 1 Rare topaz. 5 Very rare corundum. 11 Very rare zoisite. 2 Rare sphene. 7 Very rare hornblende. 12 Very rare anatase. 3 Rare biotite. 3 Very rare spinel. 13 Common pyrite. 4 Rare enstatite. 9 Very rare fluorite. 14 Very rare sphene. 6 Rare anatase. 10 Very rare topaz. Wilcox Group: Claiborne Group—Continued Deltaic: Littoral: 1. 10 miles east of Oxford. 2. 0.5 mile south of Oxford. Littoral: 3. 2 miles east of Grenada. 4. 2 miles northeast of Marion. Wilcox to Claiborne transition—neritlc or littoral: 5. 7 miles southeast of Duck Hill. Claiborne Group: Meridian Member: N eritic: 6—7. 5 miles east of Zama. 8. 18 miles east of Kosciusko. N eritic or littoral: 9. 19 miles east of Kosciusko. Winona Member: Neritic: 10. 025 mile east of Zama. 11. 23 miles north of Kosciusko. Neritic or littoral: ‘ ‘ ' 12. Meridian-Paulding road 3 miles south of Meridlan-Jackson hlghway. 13. Poplar Creek road 5 miles north of Kosciusko~Vaiden road. 14. 3 miles west of Winona. Kosciusko Member—neritic or littoral: 15. 2 miles south of Enterprise. 16. Meridian-Paulding road 5 miles south of Meridian-Jackson highway. 17. South edge of Kosciusko. 18. 12 miles west of Kosciusko. Chickasawhay Member: N critic: 19. 1.5 miles north of Stonewall. 20. 4 miles north of Newton. 21. 4.5 miles east of Walnut Grove. Neritic or littoral: 22. 4 miles north of Carthage. 23. 7 miles southwest of Thomastown. 24. Big Black River at bridge on Kosciusko-Durant highway. 25. 4 miles east of Lexington. Yegua Formation—neritic or littoral: 26. 2 miles south of Newton. 27. 0.5 mile north of Harperville. 28. 0.25 mile east of the Piekens—Canton highway just south of the Big Black River. MONTANA fine sand fraction of the sedimentary rocks in the Clai- borne Group is very constant, and monazite was pres- ent in two-thirds of the samples. The dominant min- erals are persistent laterally and vertically, and the abundance of heavy minerals is seemingly unrelated to the coarseness or fineness of the sediment (Grim, 1936, p. 201—207). Similar heavy minerals having similar characteristics, except degree of rounding, are present in the Claiborne and Wilcox Groups, which probably means that the sedimentary materials in both groups came from the same ultimate source areas in the Pied— mont. The proximate source, however, was apparent- ly older sedimentary rocks of the Coastal Plain, be- cause the heavy minerals in the Claiborne Group are more rounded than those in the Wilcox. Other char- acteristics of the sedimentary rocks of the Claiborne Group were interpreted by Grim (1936, p. 214) as showing that the rocks are of littoral or neritic origin, that they extended across the site of the Wilcox delta, and that they were deposited from many streams in— stead of one major stream. These relations are interpreted by the writer as indi- cating that the likelihood of fossil placers is greater in the Claiborne than in the Wilcox, because reworked beach deposits are probably more common in the Clai— borne. As yet no placer has been reported. SURFICIAL, FLUVIAL, AND BEACH DEPOSITS Surficial deposits on the Tom Davis farm near Co- lumbia, Marion County, were reported to contain a little gold and traces of thorium-bearing minerals (Mining World, 1949). The gold was said to be in blue clay and the thorium-bearing mineral in grave]. Doubtless the reported occurrence is detrital monazite. Although the geology of the deposit is not described. it should be noted that the locality is near the present channel of the Pearl River which extends northward into the monazite-bearing sedimentary rocks of Eocene age around Carthage, Leake County. All 13 samples of sediment from the present bed of the Mississippi River at Greenville in Washington County, Vicksburg in Warren County, and Natchez in Adams County were reported to contain less than 1 percent of monazite in the concentrate (Russell, 1937, p. 1316—1325). Beach sand on the shores and barrier islands of Mississippi Sound as far west as Cat Island, Harrison County, contains minor accessory monazite and horn— blende (Harding, 1960; Hahn, A. D., 1962, p. 1). Common heavy minerals are ilmenite, kyanite, rutile, staurolite, tourmaline, and zircon. The suites of 169 heavy minerals are similar throughout the area sampled owing probably to a common source for the sedi- mentary material. Local variation in the degree of concentration of the heavy minerals in the beach sand was interpreted by Harding to result from littoral drift toward the southwest with variable reworking of nearshore and bottom sediments. An analysis of a concentrate from Cat Island was given by Dohm (1936, p. 378—379) and is listed in table 53 in the section under Louisiana. Fine-grained ilmenite, rutile, zircon, kyanite, stauro- lite, tourmaline, and monazite occur in beach and dune sand on Ship Island, a barrier island 7 miles long and LOGO—3,600 feet wide separated from the mainland part of Harrison County by the Mississippi Sound (Hahn, 1962, p. 2—6). The heavy minerals form either bedded concentrations as much as 5 inches thick, 15 feet wide, and 100 or more feet long, or they occur as disseminated grains which lend a mottled appearance to the sand. Concentrates from less than 35-mesh fraction of the sand were said to have the following composition (Hahn, 1962, p. 6): Percent Ilmenite, leucoxene, rutile ____________________ 41 Zircon _____________________________________ 10 Kyanite ___________________________________ 25 Staurolite, tourmaline _______________________ 23. 7 Monazite __________________________________ . 3 Total ____________________________________ 100. 0 The principal source of the heavy minerals are sedi- ments discharged at the gulf coast by streams reach- ing to the crystalline rocks of the Appalachians and transported along the coast by littoral drift. In 1961 the heavy-mineral deposits on Ship Island were drilled by the US. Bureau of Mines, and only the western part of the island was found to have enough ilmenite and monazite to be classed as a possible source of these minerals (Hahn, 1962, p. 16, 23, 24): Average Weight Heavy Reserves (short Area thickness of sand minerals tons) Part oflsland (acres) of sand (million (percent) (feet) short tons) Ilmenite Monazite Eastern _______________ 779 15.0 25 1.97 ____________________ Western ______________ 665 7.7 11 5.93 209,000 800 MONTANA The earliest reports of monazite in Montana were by Day (1905a, p. 9) and Day and Richards (1906b, p. 1202—1203) and were on placer concentrates from streams in Granite County and Powell County. Dur- ing the 1950’s other workers discovered several radio- active occurrences in crystalline and sedimentary rocks in Montana, and the unusual radioactivity was locally 170 attributed to thorium. Most of these thorium occur— rences do not contain monazite. Few monazite de- posits occur in the crystalline rocks in the State, but large monazite-bearing fossil placers are present in sedimentary rocks of Late Cretaceous age. CRYSTALLINE ROCKS Carbonatite containing columbite, monazite, and an- cylite (M. H. Staatz, written commun., 1963) forms a dike in fine-grained gneiss of undescribed composition on Sheep Creek, a northward-flowing tributary of the West Fork of Bitterroot River in Ravalli County (Sahinen, 1957, p. 53—54). Vermiculite and altered biotite are present in the carbonatite, and hornblende gneiss is exposed near the deposit. A little prospect- ing was done about 1955, and the carbonatite was found to be 5 or 6 feet thick in a vertical exposure of 12 feet and to dip steeply northeastward to vertical. The monazite occurs as yellow grains in crystals of columbite. Apparently not much monazite is present, and what is there may be low in thorium because thorium was not detected in analyses of mixtures of columbite and ancylite. The thorium occurrences in the Lemhi Pass area ex- tend across the State line from Beaverhead County, Mont., into Idaho. They are described in the section on “Idaho.” Monazite occurs as a minor accessory mineral in porphyritic biotite-muscovite granodiorite and gneis- sic granodiorite exposed at Lost Horse Creek near Hamilton, Ravalli County (J afl'e and others, 1959, p. 78—7 9). These writers (p. 80—81) also reported acces- sory monazite in alaskite at an exposure about 0.5 mile southwest of the summit of Elkhorn Peak, J effer- son County. The Deer Creek district, Beaverhead County is a north-trending area 26 miles long and 12 miles wide west of Dell and south of Armstead where radioactive deposits were found in the early 1950’s (Trites and Tooker, 1953, p. 184—191; Jarrard, 1957, p. 48). Some of the deposits contain monazite. The district is un- derlain by gneiss and schist of Precambrian age which are cut by dikes of Precambrian pegmatite and is sur- rounded by shale and limestone of Carboniferous age. Cutting these rocks are stocks and dikes of Tertiary igneous rocks and locally overlying them are volcanic rocks of Tertiary age. Tertiary lake deposits and younger sediments fill the large valleys. Accessory monazite is present at Limekiln Canyon in the Deer Creek district in five small pegmatite dikes of which the largest is 9 feet wide and 23 feet long (Trites and Tooker, 1953, p. 184). Three similar dikes as much as 75 feet in length exposed about half THE GEOLOGIC OCCURRENCE OF MONAZITE a mile north of Limekiln Canyon and another pegma- tite about a quarter mile to the south of the canyon also contain minor accessory monazite. Diorite pegmatite dikes exposed between the North Fork of Deer Creek and Bell Canyon contain acces- sory monazite and allanite. The monazite may be rich in thorium oxide, because spectrographic analyses of the mineral show thorium, cesium, and phosphorus as major constituents, lanthanum and silicon as minor constituents, and yttrium, calcium, magnesium, and lead as trace constituents (Trites and Tooker, 1953, p. 187), but chemical analyses for thorium oxide have not been reported. Some biotite-rich parts of contact- metamorphic zones adjacent to the dikes are unusually radioactive, probably owing to monazite disseminated in the altered zones. Elsewhere in Montana, monazite seems to be unre- ported from granitic pegmatites although all‘anite is very common (Heinrich, 1949, p. 29—32). FOSSIL PLACERS Ilmenite-bearing fossil placers in sandstone of Late Cretaceous age were discovered in 1911 and 1912 by Stebinger (1914, p. 329) in northwestern Montana. Stebinger’s account of the placers does not specifically mention monazite as one of the detrital minerals, and even as late as 1946 a report on the detailed examina- tion of a fossil placer in Teton County did not disclose monazite (Wimmler, 1946, p. 4). The search for radioactive materials in the 1950’s, however, showed that many of the fossil placers contain small amounts of monazite and other radioactive minerals (Murphy and Houston, 1955, p. 190, 192). The fossil placers in Montana are part of a band of like deposits that occur discontinuously in sandstone formations of Late Cretaceous age exposed along the east front of the Rocky Mountains from the border between Montana and Canada through Wyoming and Colorado into New Mexico. In Montana the fossil placers occur in the Virgelle Sandstone Member, the Horsethief Sandstone, and the St. Mary River Forma- tion (Murphy and Houston, 1955, p. 190; Armstrong, 1957b, p. 215). Most of the fossil placers are beach deposits formed at the transition between marine and nonmarine sediments, but the placers in the St. Mary River Formation are 800—900 feet above the highest marine fossils and are probably stream or estuarine deposits (Murphy and Houston, 1955, p. 190). In most areas fossil placers occur in several stratigraphic horizons. Apparently these deposits represent suc- cessive retreats and advances of the sea. Individual fossil placers are elongate and lenticular and are not persistent for long distances (Murphy and MONTANA Houston, 1955, p. 190). Their actual size is rarely determinable from the outcrops. Most are less than 4 miles long and 5 feet thick. A placer was drilled at the Devils Basin about 20 miles north of Roundup, Musselshell County, and the thorium-bearing parts were found to be from 2 to 10 feet thick (J arrard, 1957, p. 50). Inasmuch as they tend to be narrow and elongate like black sand deposits on present beaches, most of the fossil placers are probably no wider than 1,000 feet, and many may be much smaller. The fossil placers are well cemented by hematite and carbonate minerals and are more resistant to ero- sion than beds in the same sequence that lack concen— trations of heavy minerals. For the most part, the sandstones in which the placers occur are coarse grained, gray, cross-bedded, and massive and are com- posed chiefly of quartz and altered feldspar (Stebin- ger, 1914, p. 330; Armstrong, 1957b, p. 215). The heavy minerals in the fossil placers consist of common ilme- nite, anatase, magnetite, and zircon, less common gar- net and rutile, and sparse monazite, tourmaline, epi- dote, staurolite, spinel, ilmenorutile, and sphene. Mona- zite makes up less than 1 percent of the heavy min— erals in the fossil placers. The unusual radioactivity of the placers probably comes mainly from zircon. The principal areas of monazite-bearing titaniferous fossil placers in Montana are in a belt defined approxi- mately by Choteau in Teton County on the northwest, Great Falls in Cascade County on the northeast, Har- lowton in Wheatland County on the southwest, and Roundup in Musselshell County on the southeast (J ar- rard, 1957, p. 49—50). Monazite-bearing placers have been listed at eight localities in the Vicinity of Cho- teau (Murphy and Houston, 1955, p. 195). Northwest of the main area, monazite-bearing fossil placers occur at three localities near Cut Bank, Glacier County (Murphy and Houston, 1955, p. 195). Substantial tonnages of monazite seem to be present in these fossil placers, but the indicated tenor—less than 1 percent of monazite in the concentrate—of the few deposits that have been evaluated shows that the monazite could be recovered only as a coproduct with the titaniferuos minerals and zircon, neither of which can be mined under technological conditions of 1962. PRESENT STREAM PLAGERS Magnetite—rich monazite—bearing concentrates from recent placers were described by Day and Richards- (1906b, p. 1202—1203) from Princeton in Granite County and from an unspecified locality in Powell County. Later the occurrence at Princeton was de- scribed as a monazite-bearing natural black sand placer of unknown extent (Rowe, 1928, p. 818; Waldron and 171 Earhart, 1942, p. 179). The occurrence in Powell County has not been further described, but the original account stated that the concentrate came from sand containing only 3 pounds of heavy minerals per cubic yard. As reported by Day and Richards, the com- position of the concentrates from the two counties was as follows: Pounds per short ton Granite Powell County County Magnetite ______________________________ 1, 952 1, 779 Chromite _____________________________________ 17 Ilmenite ________________________________ 10 _______ Garnet _______________________________________ 128 Monazite _______________________________ 6 16. 3 Zircon ________________________________________ 8 Undetermined ___________________________ 32 _______ Total _____________________________ 2, 000 1, 948. 3 Gold and platinum were present in the concentrate from Granite County, and gold was present in the one from Powell County. Monazite also occurs in Little Gold Creek in Granite County (Lyden, 1948, p. 41). The stream is a tribu- tary of Boulder Creek. Gravel from Little Gold Creek was reported by Lyden to contain about 5 pounds of concentrate per cubic yard, and the concentrate con- sists of ilmenite, wolframite, and monazite and very sparse gold and platinum. Monazite—bearing stream placers at Victor and Mc- Calla and in Rye Creek in Ravalli County were ex- plored by the US. Bureau of Mines in the early 1950’s, but the results of the investigations were not published (Eilertsen and Lamb, 1956, p. 12). Appar- ently the deposits in the Victor and McCalla area have fairly large volume and fairly high tenor, and the monazite contains 6 percent of Th02 and 0.52 per- cent of U308 (Kaufi'man and Baber, 1956, p. 6, 10). Monazite placers occur along Trail Creek in Beaver- head County (Eilertsen and Lamb, 1956, p. 12), but apparently they are neither as large as nor have as high a grade as those in the Victor and McCalla area. Monazite from the Trail Creek placers contains 4.10 percent of Th02 and 0.10 percent of U303 (Kauff- man and Baber, 1956, p. 6). Placers at Price and Powder Gulch in Silver Bow County contain monazite, but details were not pub- lished (Eilertsen and Lamb, 1956, p. 12). Stream concentrates from Madison County were re- ported to contain monazite as early as 1905 (Day, 1905a, p. 9). In 1907, monazite associated with small amounts of thorianite, xenotime, zircon, and spinel and considerable amounts of magnetite, ilmenite, and garnet was discovered at Norris, Madison County, in a stream placer in an area underlain by granite gneiss 172 (Sterrett, 1908a, p. 791). The monazite—bearing placer concentrate examined by Day may have come from the Norris area, but the way the discovery in 1907 was described it seems likely that it is from a difl'erent locality. Subsequent accounts, however, mentioned only the monazite from Norris in descriptions of the minerals in Madison County (Rowe, 1928, p. 818; Waldron and Earhart, 1942, p. 179, 199). NEBRASKA Two 2,000-pound samples of sand from Milford in Seward County, were reported by Day and Richards (1906b, p. 12024203) to contain a trace each of mona- zite. The source of the sand was not described. NEVADA Granite augen gneiss near Mesquite in Clark Coun— ty was reported to contain as much as 2 percent of monazite and 5 percent of xenotime in individual sam- ples (Young and Sims, 1961, p. 274). The deposit was said by M. H. Staatz (written commun., 1963) to be across the State line in Mohave County, Ariz. Other accessory minerals in the gneiss are sparse hornblende, limonite, magnetite, zircon, and allanite( ?). The size and average tenor of the occurrence has not been evaluated. Minor occurrences of monazite in Clark County have been reported (Mineralogist, 1950) in the Clark Mountain and Crescent Peak areas, where the monazite is associated with bastnaesite in granite gneiss, and in the Gold Butte mining district, where monazite is doubtfully present in biotite pegmatite of Precambrian(?) age (Lovering, 1954, p. 80). Two auriferous concentrates from placers in the Vicinity of Carson City, Ormsby County, were found by Day and Richards (1906b, p. 1204—1205; Lincoln, 1923, p. 279) to contain the following amounts of monazite: Pounds per short ton A B Magnetite ______________________________ 1, 387 1, 190 Chromite _______________________________ 485 168 Garnet _________________________________ 41 353 Monazite _______________________________ 29 5 Zircon __________________________________ 21 80 Quartz _________________________________ 9 5 Total _____________________________ 1, 972 1, 801 Specific sources for these concentrates were not cited, but B was described as coming from alluvium(?) con- taining 12 pounds of black sand per ton. NEW HAMPSHIRE The only described occurrences of monazite in New Hampshire are localities where monazite is present as a minor accessory mineral in crystalline rocks. Mona- THE GEOLOGIC OCCURRENCE OF MONAZITE zite was first reported in 1892 in gneiss at Randolph in Coos County and at Wakefield in Carroll County, and possible accessory monazite in oligoclase gneiss was reported at Swanzey in Cheshire County (Derby, 1891a, p. 205; Am. Naturalist, 1892). In the 1940’s and 1950’s several monazite localities were reported by M. P. Billings and others in detailed studies of the geology of the State. The distribution of these local— ities and the modes of occurrence of the monazite are closely related to the regional geology. New Hampshire is underlain by sedimentary and volcanic rocks that range in age from Ordovician( ?) to Mississippian( ’9) (Billings, 1956, p. 5—6). Devonian and older sedimentary and volcanic rocks have been regionally metamorphosed to the greenschist, albite- epidote-amphibolite, and amphibolite facies. Volcanic rocks of Mississippian( ?) age were not involved in the regional metamorphism, but they have been slight— ly affected by contact metamorphism. The metasedi- mentary rocks are folded into a major northeast—trend- ing synclinorium which occupies most of the State and in which the rocks are of the upper subfacies of the amphibolite facies. Flanking the central syncli- norium is an anticlinorium in the southeastern part of the State and an anticline adjacent to the State lines of Vermont and Connecticut. In these anticlinal struc- tural features the grade of the metamorphism declines to the greenschist facies. Emplaced in the metamor- phic rocks are seven groups of plutonic rocks of which the oldest is probably Precambrian or early Paleozoic in age and the youngest is probably Mississippian( ?) in age (Billings, 1956, p. 5—6). Among the metasedimentary and metavolcanic rocks, monazite has only been reported from the Early Devonian Littleton Formation where this unit has been metamorphosed to the middle and upper sub- facies of the amphibolite facies. In a study of the minor accessory minerals in the rocks of the Lovewell Mountain and Keene quadrangles, Heald (1950, p. 44, 68) found that six out of seven samples of sillimanite schist and quartz-mica schist contained small amounts of monazite (table 55). Allanite, which is an espe— cially common mineral in the lower grade metasedi- mentary and metavolcanic rocks and in retrogressively metamorphosed plutonic rocks (Billings and Keevil, 1946, p. 801—810; Gottfried, 1954, p. 204—205), is not present in the high—grade gneisses sampled in the Lovewell Mountain and Keene quadrangles. The Keene quadrangle includes Swanzey where Derby (1891a, p. 205) reported monazite. Among the seven groups of plutonic rocks recog- nized in New Hampshire, only a few members of the New Hampshire Plutonic Series are monazite bear- NEBRASKA, NEVADA, NEW HALA‘PSHIRE, AND NEW JERSEY TABLE 55.—Mineralogical composition, in weight percent, of heavy- mineral fraction of the rock, in the Lovewell Mountain and Keene quadrangles, New Hampshire [Modified from Heald (1950, p. 68). Symbol used: Tn, trace] 173 parts per million of U and Th to percentages of U308 and Th02, the measured abundance of U308 and estimated abundance of Th02 in the monazite are: 1 2 3 4 5 6 7 8 Biotite _________________ 12 27 31 14 17 16 19 8 Garnet _________________ .3 .8 6 2 . 05 2 .3 .4 Sillimanite. _. 0 1 1 4 Tr. . 03 . 0 . 03 Kyanite _______ .0 Tr. .4 01 .0 Tr. .0 .0 Tourmaline. _ . .02 . 5 .0 0 Tr. .0 .0 . 0 Chlorite_.__ .0 .0 .0 2 .0 .1 .0 .0 Apatite. .03 .05 .8 1 .2 .1 . 03 .03 Zircon.-- 002 . 008 . 004 008 . 003 . 05 .01 . 02 Monazite 002 . 002 . 0 004 005 . 02 . 002 . 009 Sphene _____ 0 .005 Tr. 02 04 . 1 . 0 04 Magnetite _____ 06 . 07 1 5 1 1 . 03 1 Pyrite _________ __.. 0 .0 .0 2 05 .1 .0 0 Opaque minerals ....... . 3 .3 .5 2 2 .3 2 3 1. Littleton Formation, average of 2 specimens of mica schist from middle-grade zone, Keene area to the southwest of the Lovewell Mountain quad. 2. Littleton Formation, average of 2 specimens of mica-quartz schist from high-grade zone. 3. Littleton Formation, biotite gneiss from high-grade zone. 4. Littleton Formation, average of 2 specimens of pyritiferous gneiss from high-grade zone. 5. Bethlehem Gneiss. 6. Kinsman Quartz Monzonite, average of 3 specimens from Bacon Ledge pluton. 7. Kinsman Quartz Monzonite, small pod in schist. 8. Granodiorite from late dikes, average of 2 specimens. ing, and they only contain monazite where they are emplaced in high—grade metasedimentary rocks. The Bethlehem Gneiss, Kinsman Quartz Monzonite, and granodiorite of the New Hampshire Plutonic Series contain from 0.004 to 0.02 percent of monazite (table 55) in the Lovewell Mountain quadrangle (Heald, 1950, p. 68). Bethlehem Gneiss in the Bellows Falls quadrangle in Cheshire and Sullivan Counties (Kru- ger, 1946, p. 183), the Sunapee quadrangle in Sullivan and Merrimack Counties (Lyons and others, 1957, p. 533), and the Moosilauke quadrangle in Grafton County (Billings and Keevil, 1946, p. 810—813) con- tains accessory monazite. Concord Granite and asso- ciated pegmatite of the New Hampshire Plutonic Series contains monazite in the Cardigan quadrangle, Grafton and Merrimack Counties (Lyons and others, 1957 , p. 533; Morrill, 1960, p. 18; Cameron and others, 1954, p. 1). The monazite reported by Derby (1891a, p. 205) at Wakefield is probably from sillimanite-grade gneiss of the Littleton Formation, but its source is uncertain. The monazite from the vicinity of Randolph is pos- sibly from a similar, but also uncertain, source. Analyses of the uranium and estimates of the thorium in monazite from the Kinsman Quartz Monzonite, Bethlehem Gneiss, and Concord Granite were made by Lyons, Jafl’e, Gottfried, and Waring (1957, p. 533). The abundance of thorium was estimated according to the equation: a=0.366 U+0.0869 Th Where a is alpha activity per milligram per hour, U is the uranium content in parts per million, and Th is the thorium content in parts per million (Lyons and others, 1957, p. 529). Converting the published results from U308 2 (measured) (estimated) Rock Quadrangle Percent Kinsman Quartz Lovewell Moun- 0. 16 5. 06 Monzonite. tain. Bethlehem Gneiss _____ Sunapee __________ . 30 2. 48 Concord Granite ______ Cardigan _________ . 07 3. 25 The indicated abundances of thorium oxide for the monazite from the Bethlehem Gneiss and Concord Granite are about half as great as the abundance commonly found in monazite from plutonic rocks associated with rocks of the sillimanite-almandine subfacies, but the indicated abundance of thorium oxide in monazite from the Kinsman Quartz Monzonite is very typical of monazite associated with rocks of this metamorphic grade. The absence of monazite from the Oliverian and Highlandcroft Plutonic Series, which are older than the New Hampshire Plutonic Series, may relate to the low-grade metamorphism which affected those rocks but not the younger series (Lyons and others, 1957 , p. 529). Allanite, epidote, and sphene are par- ticularly common in the low—grade metamorphosed plutonic rocks but are rare in the New Hampshire Series. Monazite seems to be absent from the thorium ox— ide-rich White Mountain Plutonic Series (Billings and Keevil, 1946, p. 801—810). The rocks are Missis- sippian( ’9) in age and include both intrusive and ex— trusive phases. Allanite and sphene are common ac- cessory minerals. Monazite is found in apparently equivalent rocks at Ascutney Mountain, Vt., in which primary allanite mantles the monazite. Possibly the mantles of allanite indicate that monazite is unstable where the magma reaches hypabyssal or effusive en- vironment and that reaction between earlier formed monazite and magma give allanite as one product. The general presence of allanite and absence of mona- zite in the series might then be related to this reaction. NEW JERSEY The Canfield phosphate mine 2 miles west of Dover, Morris County, contains a granular aggregate of mag- netite and apatite with which are associated small amounts of quartz, feldspar, and biotite and very sparse monazite (McKeown and Klemic, 1953, p. 19— 20, 58). Monazite and zircon were reported to form most of a rust-brown rock near Chester and Tanners 174 Brook in Morris County (Markewicz and others, 1957). Dense fine-grained reddish—brown monazite from the Chester area was reported by Molloy (1959, p. 510) to have been analyzed by Ledoux and Co. of Teaneck, N .J ., the monazite was found to contain 13.66 percent of ThOz, 53.36 percent of RE203, 25.31 per— cent of P205, and 0.045 percent of U308. The mona- zite is cut by nonradioactive quartz veins and, at the time of this writing, had not been found in place but occurred as fragments in residuum containing frac- tured blocks of quartz-feldspar granite. A crystal of monazite was found in pegmatite float at the Ringwood mines about 4 miles east of the south end of Greenwood Lake at Ringwood, Passiac Coun- ty. Biotite-rich phases of the Byram Granite Gneiss locally contain noticeable amounts of monazite at West Milford near Ringwood (Markewicz and others, 1957). Quartz-feldspar pegmatite exposed on the Poronowicz farm at the northwest edge of the village of Oxford Furnace, Warren County, contains sparse magnetite and monazite (McKeown and Klemic, 1953, p. 49, 60). Ilmenite sands in the Cohansey Formation of Plio- cene( ?) age, the Kirkwood Formation of Miocene age, and the Cape May Formation of Pleistocene age in ' Ocean and Burlington Counties in southern New Jer- sey contain very small amounts of monazite (Marke- wicz and Parrillo, 1957; Markewicz and others, 1958, p. 6—8). The fossil placers occur in stream channels in the Cohansey Formation and in marine deposits in the Kirkwood and Cape May Formations. Samples from 200 auger holes disclose that the sand contains an average of 3 percent of heavy minerals. Illmenite, rutile, and zircon make up about 85—98 percent of the concentrate. Associated with them are anatase, leucox- ene, staurolite, kyanite, sillimanite, tourmaline, anda- lusite, amphibole, hypersthene, garnet, epidote, mona— zite and sparse glauconite. At most places these min- erals never amount to more than 1 or 2 percent in- dividually, and commonly they totaled less than 2 percent of the concentrate. Ordinary sands from the Cape May Formation ap— parently contain just a trace of monazite. Out of nine samples from the Cape May Formation examined by McMaster (1954, p. 62—170) in a study of the beach sands of New Jersey, only two contained even a trace of monazite (table 56). These samples came from West End, Monmouth County, and Highbee Beach, Cape May County. Of 39 beach sand samples for which mineral anal— yses were given by McMaster (1954, p. 62—170), 9 con- tain monazite, and of the 15 sea-bottom samples for which analyses are given 7 are monazite bearing (table 56). Ordinarily the monazite is merely a trace in the THE GEOLOGIC OCCURRENCE OF MONAZITE medium or finest grain sizes, but in several samples from each environment it appears in the coarse sizes (table 56). The distribution of the monazite-bearing beach sand is fairly regular southward on the coast and does not seem to be related to the geomorphic form of the beach. Thus, it is present in beach sand on the spit and bay bar at and south of Sandy Hook, Monmouth County; in beach sand on the barrier bars as at Seaside Park, Island Beach, and Surf City, Ocean County; and in sand on beaches formed on the mainland at Cape May (McMaster, 1954, p. 1—2). Con- centrations of monazite were not found on the beaches, presumably because the source materials from which the beaches were formed were so lean in monazite. NEW MEXICO The first reported occurrences of monazite in New Mexico were in sand associated with gold placers, the most frequently mentioned occurrences are in pegma- tite dikes, and the economically most favorable occur- rences are in fossil placers in Upper Cretaceous sand- stone. Large resources of monazite seem to be present in the fossil placers. CRYSTALLINE nocxs The Petaca Mountains pegmatite district, including the Tunas Mountains, Rio Arriba Mountains, and the Ojo Caliente district in Rio Arriba County have been the source of museum specimens of euhedral and mas- sive monazite (Hess and Wells, 1930, p. 19; Just, 1937, p. 18; J ahns, 1946, p. 64, 66; Palache and others, 1951, p. 695; Anderson, E. C., 1957, p. 106, 161) and may have been the source of the samples of monazite from New Mexico examined by the US. Bureau of Mines in 1922 (Queensland Govt. Mining Jour., 1922, p. 247). The Petaca district is a belt of pegmatites in Precam- brian metamorphic and igneous rocks that extends northwestward 40 miles from Ojo Caliente to the west end of Jawbone Mountain (Just, 1937, p. 40—48; J ahns, 1946). At its greatest width the belt is 9 miles wide. The Precambrian rocks consist of feldspathic hornblende-chlorite schist formed through the meta- morphism of flows of basalt and andesite, with which are associated schistose rhyolite and trachyte, conglo- merate, quartzite, and quartz-muscovite schist. These rocks are extensively epidotized and silicified, particu- larly in contact zones adjacent to masses of granite. The granite varies widely in texture but is generally medium grained, nonporphyritic, and granulated. It also varies widely in composition; where ferromagne- sian minerals are lacking, it is pink but where biotite is present, it is gray. Aplite dikes and quartz veins are present in the metamorphic rocks near the granite. Pegmatite dikes in the Petaca district are small, and they have irregular shape, simple mineralogical 175 .3550 has 230 £23m gnmfim “a 08605 023.50% mg 250 .3 .8 .3550 5:05:02 .cnfl 083 3 :oflmfihom ha: 930 .cm .9 .3550 .32 230 $32 250 «0 03.0508 85: n 5.80 035.54 .E .3550 580 525 «mm 235 no 3:8 3 580 2222 .2 .3550 580 in: 30 2:5 as 3:8 S $80 2:53. .2 . .3560 $80 523 30 235 no 2:: m5 580 955:4. .2 E .3550 580 525 $0 235 .2 .3580 53852 £00m Exam B 9895.8: 3:5 3 580 222.2 .fi .3560 5:05:02 .Moom mun—aw «o 55: 305 m .30 M8? 302 .3 .3580 .32 250 6830:? . .3560 .32 .250 $30 0:st 8m .230 :85 SEES 0e 55: 2E 30 . 43550 ufinusau .oEuCamEm $2500 580 .93ku 08609 «0 E30 £5: “a £08 0:5 ad .3580 580 5:0 «Em .3550 380 .auaom 0:23 .Efifim 03:0 3.80 we 5:3. 2:: m... (3:000 5800 {Em oanm 43580 53ch diam 3—53. F! dsdac m“ Nevsv" .3550 5:05:02 .Mooonam tom .— I Iv-(v-‘VNO NEW MEXICO INH .F. lav-1m N d9 #9 «H H 1.: E‘ H I; P v n HHHN mm «H WHH H a: E InH v n 1.: . E1 . H h m H HHm H ii 011‘ Capt—1H #5 3 o .m In: E" H Emfinn N H m I v I»; .wth ¢ 6N0 He“ :9 .I In“ M H 0' H255: IQ :wOH .Ncw Igmhagwwwm c'H'N' H INGI‘IOQ‘wa H OH. I ‘0 H' .NwNHaNn HHdeHH N H' .wm o ‘8’»; N .. ....:‘g I. . . HV‘v-fi h I .ocwwv‘no l©§°°® ........ - .mmwflu :32:— .:= 0:» H023? .ofi .3058 .mucwfiwaa 52$ ............... ccomooaoa .. .2505?” 0093.. M35 ................... 382m ................... SEEN ................. 83252 ............... wannao=o0 ................ 232250 ................... 35:4 .................... :8ng ................ 3:20.89 .............. 2:20:50. ................... 25.3w ................ 8:8:an ............... EESEEw ................... 255m ................ 33832 .................. cawaamvH ............. afififloahm .............. wuawEEowH ............... 388520 o H' as h d N H MHmc H H v H m oi « o'Hu-«V‘h b d—IHN m nnowwh Hc'H‘ s .cm w .3 5?. 3 c .3. £anan “553-3%.6 afiw E 2.30:2: fraum mvH .0 3a .0 moH .0 SN .0 3H .0 3H .c «B .o 3H d 3H .0 SN .o a3 .9 a H N 9' Ch G H o' «no 6 m3 .0 3H .0 . .EE .......... E0523 wamfionéfinfisfi we 35 NN HN cw @H wH hH eH nH «H MH NH HH 2 $5858 85cm 3:25:03 «538.0800 350.00% :30: 503% T. ”moms :9 60m: Hon—Em .efié d {30 .3329: Sea 8982. 5 $23. 3»? VS £§§§ow 23350 Sat. ”83:53:00 ugfgaéfinufies Re £883.“. 3S§S§§0§ Me c3033 30:33ng Fe .fiofifiEHSou Naugsswfigldm Hamid. 176 composition, and homogeneous structure where they occur in the granite. Dikes in the metamorphic rocks are parallel to the strike of the foliation but trans— gressive to the dip; they are mica rich and of complex mineralogy. Most concentrations of fluorite, colum- bite, monazite, beryl, and samarskite occur in the dikes in the metamorphic rocks. Monazite, is a common minor constituent of albite-rich parts of the pegma- tites (J ahns, 1946, p. 64). It occurs as well-developed flattened crystals, as coarse crystals and equant masses weighing as much as 10 pounds, and as thin tabular and elongate crystals. The monazite is light to dark brown, and feldspar surrounding the monazite is com— monly stained yellowish brown to deep brick red. Large monazite crystals are fresh, but some thin tab- ular ones are altered to brown earthy powder (J ahns, 1946, p. 65). The specific gravity of monazite from the Petaca district is 5.0 (Northrop, 1944, p. 219). The monazite in the pegmatites of the Petaca district is a minor accessory mineral that cannot be commer- cially exploited, although a small market once existed for museum specimens. Monazite-bearing pegmatites in the district have been individually mentioned as occurring in the Frid- lund, Cribbensville, Silver Spur, North Star, Freet- land, Coats, Pinto Verde, Globe, Alamos, Apache, N ambe, and Capitan deposits (Hess and Wells, 1930, p. 17; Just, 1937, p. 63—64; Northrop, 1944, p. 219; Jahns, 1946, p. 64—65). Several chemical analyses have been made of mona- zite from the Petaca district, and material doubtfully from the Petaca district has been analyzed. The first of these analyses, and the one for which the location is doubtful, is of a crystal collected by P. Krieger and sent by A. C. Lane in 1935 to Friedrich Hecht and Edith Kroupa in Vienna for microchemical analysis (Lane, 1935, p. 19, 43—45). Originally the crystal was thought to have come from about 11 miles from Glo- rieta, Santa Fe County, but subsequently it was found that the monazite possibly, but by no means certainly, came from Petaca (Muench, 1938a, p. 2661; 1938b; Northrop, 1944, p. 219; Bates and Burks, 1945, p. 77). As determined from microanalysis by Hecht and Kroupa, the composition of this “Glorieta” monazite is (Lane, 1935, p. 44): Percent Percent Rare earths _________ 58. 36 CaO _______________ 0. 05 Th0; ______________ 10. 67 MgO ______________ . 68 U303 ____________________ Pb ________________ . 392 P205 _______________ 26. 09 Loss on ignition _____ 1. 72 8102 _______________ 2. 97 ——— A1203 ______________ . 67 Total _______ 1 102. 55 F0203 ______________ . 95 1 Given as 102.16. THE GEOLOGIC OCCURRENCE OF MONAZITE Muench (1938a, p. 2661; 1938b) reported that he was given a piece of monazite by Rufus C. Little who had collected it at the Cribbenville mica mine near Petaca. Meunch made six determinations of, the thorium content and three determinations of the uranium content. These determinations are here recalculated to show 8.54, 8.60, 8.61, 8.54, 8.50, and 8.57 percent of ThOz and 0.127, 0.118, and 0.127 percent of U308. The average T1102 content is 8.55 percent, and the average U303 content is 0.124 percent. The composition of total rare earth plus thorium oxide precipitate from monazite from pegmatite in the Petaca district was described by Murata, Rose, and Carron (1953, p. 294) and is recalculated to sum 69.62 percent—its percentage in the monazite (H. J. Rose, Jr., 1958, written commun.): Percent 113.203 _____________________________________ 12. 94 C602 ______________________________________ 25. 95 PrGOu _____________________________________ 2. 95 Nd203 _____________________________________ 12. 66 8111203 _____________________________________ 4. 01 Gnga _____________________________________ 1. 90 Y203 ______________________________________ 1. 69 Th02 ______________________________________ 7. 52 Total ________________________________ 69. 62 The pegmatite dike at the Harding mine, Taos County, contains monazite as an extremely minor ac- cessory mineral (J ahns, 1953, p. 1090). The Pidlite mine in the Sangre de Cristo Range in southwestern Mora County is driven in a monazite- bearing lithia pegmatite dike that intrudes Precam- brian rocks (Jahns, 1953, p. 1078). The dike is lens shaped and consists of four mineralogical and textural zones, which have a regular concentric arrangement, and three replacement units. Granitoid aggregates of quartz, albite, perthite, and muscovite in variable abundance form relatively thin and continuous outer zones, and very coarse grained aggregates of quartz and perthite make up lenticular or podlike inner zones. The three replacement units have irregular tex- ture and contain abundant sodic albite, lepidolite, and white to pink muscovite. Accessory minerals in the dike are amblygonite, apatite, beryl, betafite, bismuth, bismutite, columbite-tantalite, cyrtolite, fluorite, gah- nite, loellingite, magnetite, microlite, monazite, pyrite, spessartite, spodumene, topaz, and tourmaline. Mona- zite, betafite, and fluorite occur in the wall zone of the pegmatite, and monazite, tourmaline, lepidolite, fluorite, columbite-tantalite, and albite occur in the inner zones of the dike (J ahns, 1953, p. 1093—1094). Monazite is sparse. The zones in the dike were interpreted by J ahns (1953, p. 1079) to have formed from the fractional NEW MEXICO crystallization of pegmatite magma in a virtually closed system. Formation of the younger minerals, among which monazite seems to be classed, apparently took place chiefly through direct crystallization and partly through replacement of earlier-formed minerals by residual fluid. Monazite has been reported from several pegmatite dikes in the Elk Mountain district, Ribera district, and Manzanares Creek area of San Miguel County (Northrop, 1944, p. 219; Crawford, 1956, p. 1212; Anderson, E. C., 1957, p. 13, 29). Anderson also re- ported that monazite is a common accessory mineral in many masses of granite in San Miguel County. It was said to be particularly common in alteration zones and along the contacts of the granite masses. Monazite from a vein deposit at Pecos, San Miguel County, was reported to contain 9.86 percent of Th0;. and 0.34 percent of U308 (Kauffman and Baber, 1956, p. 6). Monazite from an undescribed locality in San Miguel County was said to contain 10—12 percent of Th02 (Crawford, 1956, p. 1212). Fairly large pieces of monazite have been found in the region southwest of Las Vegas and in the vicinity of Bull Creek in San Miguel County (Northrop, 1944, p. 220). Monazite from the Bull Creek locality was analyzed by O. B. Muench and found to have 10.7 percent of T1102 and 0.14 percent of U308 (Northrop, 1944, p. 220; Muench, 1950, p. 130). The location, size, and composition of the monazite suggest a peg- matitic source. In the Dalton Creek area on the east side of the Sangre de Cristo Range east of Santa Fe, Santa Fe County, a few pegmatite dikes contain minor accessory monazite (Anderson, E. C., 1957, p. 119). Micro- scopically small crystals of monazite were reported from the Organ district, Dona Ana County, but the nature of the occurrence was not described (Northrop, 1944, p. 219). FOSSIL PLACERS Numerous radioactive fossil placers have been found in Upper Cretaceous sandstones of the San Juan Basin in New Mexico (Chenoweth, 1956; 1957, p. 212; Dow and Batty, 1961, p. 3). Similar fossil titaniferous black sand deposits occur in Arizona, Colorado, Mon- tana, Utah, and Wyoming. The fossil placers are beach concentrates formed at the transition zone from marine to nonmarine beds, and they occur in the Gallup Sandstone, Dalton Sandstone Member of the Crevasse Canyon Formation, Point Lookout Sand- stone, and Pictured Cliifs Sandstone. The fossil plac- ers form resistant elongate, lenticular beds associated with clean massive well—sorted littoral marine sand- 177 stone which is overlain by lagoonal deposits consisting of coal and shale (Chenoweth, 1957, p. 212). The fossil placers contain ilmenite, hematite, anatase, gar- net, zircon, tourmaline, magnetite, rutile, monazite, and several as yet unidentified minerals cemented with carbonate and hematite. Only very sparse monazite has been reported. Many of these placers were dis- covered because of their unusual radioactivity due to monazite and zircon, and some of the placers have been explored for their titanium-bearing minerals. The possibility of economic development of the placers apparently depends on their titanium content, and monazite might be a byproduct. The largest group of fossil placers, called the Shiprock group in New Mexico and the southwest Mesa Verde deposits in Colorado, are in the upper part of the Point Lookout Sandstone and lower part of the Menefee Formation exposed between Shiprock, San Juan County, and the State line near Tanner Mesa (Cheno- weth, 1957, p. 215—216; Dow and Batty, 1961, p. 40—44). At least 28 separate deposits are known in New Mexico, and the deposits extend northwestward into Colorado (Dow and Batty, 1961, fig. 28). They are poorly and discontinuously exposed, small, and low grade. For the group as a whole, including the extension of the deposits in Colorado, the total tonnage of black sand was estimated as 693,000 short tons having an average grade of as follows (Dow and Batty, 1961, p. 43): Percent TiOz ______________________________________ 2. 8 Zr02 ______________________________________ . 42 Th02 ______________________________________ . 03 A semiquantitative spectrographic analysis of black sand from the Shiprock area is given in table 57. TABLE 57.—Semiquantitative spectrographic analysis of a bulk sample of a heavy-mineral deposit in the Point Lookout Sand- stone exposed in the Shiprock area of New Mexico and Colorado [Analystz Chenoweth (1957, p. 214—215). Theoretical range, in percent: xx, >10; x, 1.0—10.0;. x+, 0.464—1.0; .11, 0215-0464; .x—, 0.10—0.215] Silicon __________ xx. Copper _________ . Ox— Aluminum _______ x. Lanthanum ______ . x + Iron ____________ x +. Niobium ________ . 0x + Titanium--- _ _ _ _ _ xx. Neodymium _____ . x Manganese ______ . x— Nickel __________ . 0x— Calcium_-______ _ .2: Lead ___________ . 0x— Magnesium ______ . x + Scandium _______ . 0x— Barium _________ . 0x Thorium ________ . x+ Beryllium _______ . OOOX— Vanadium _______ . x— Cerium _________ . x Yttrium _________ . x — Cobalt __________ . Ox— Ytterbium _______ . 0x — Chromium ______ . 0x + Zirconium _______ x +. A low concentration of heavy minerals in a fossil placer in the Pictured Cliffs Sandstone at Barker 178 dome in north-central San Juan County is radioactive and presumably monazite-bearing (Chenoweth, 1957, p. 216—217). Four monazite-bearing fossil placers were found along the Hogback monocline south of the Shiprock placer area (Chenoweth, 1957, p. 216). Two placers are in the top of the Point Lookout Sandstone, and two are in tongues of the sandstone in the Menefee Formation. The largest placer is at least 525 feet long. A large fossil placer in Menefee Formation is ex- posed 2 miles north of Sanostee, San Juan County (Chenoweth, 1957, p. 215; Dow and Batty, 1961, p. 37—40). It is 7,300 feet long, 200—800 feet wide, and 1—14 feet thick. Titanium minerals, magnetite, zircon, and monazite are visibly laminated with quartz and feldspar and cemented by hematite. An analysis of four samples from the placer disclosed an average con- tent of 15.6 percent of TiOz, 2.6 percent of Zr02, and 0.12 percent of eTh02 (Dow and Batty, 1961, p. 40). Two miles south-southeast of Toadlena, San Juan County, a monazite-bearing titaniferous layer in the Gallup Sandstone is exposed for a strike-length of 500 feet, this layer was thought to be as much as 1,750 feet long, but both ends are covered by alluvium (Chenoweth, 1957, p. 215; Dow and Batty, 1961, p. 37). The layer is 1 foot thick and was reported to contain from 0.4 to 32 percent of TiOz and 0.06 per- cent of eThO2. A small fossil placer is exposed in the Gallup Sand- stone 1 mile north of Defiance and 8 miles west of Gallup, McKinley County (Allen, J. E., 1956; Dow and Batty, 1961, p. 37 ). It is exposed along both walls of a canyon for a length of 1,500 feet and has a thickness of 1 foot, but its width is unknown. Brook- ite, rutile, anatase, and leucoxene were said by Allen to be common, but an average of three analyses from the deposit disclosed only 0.5 percent of Ti02 and 0.02 percent of eThOZ (Dow and Batty, 1961, p. 37 ). Radioactive zircon was said to be one of the minerals in the placer, but monazite was not specifically men- tioned. A fossil placer in the Point Lookout Sandstone occurs 4.5 miles southeast of Standing Rock Trading Post, McKinley County (Chenoweth, 1957 , p. 216). Erosion has divided the original deposit into two parts, both of which are flat-lying beds of titaniferous sand- stone. The western part of the placer is 3,500 feet long, 100 feet wide, and 3 feet thick; the eastern part is 2,100 feet long, 350 feet wide, and 8 feet thick (Dow and Batty, 1961, p. 37 ). An average of 4.3 percent of TiO2, 0.3 percent of ZrOZ, and 0.06 percent of eTh02 was reported by Dow and Batty from three analyses. THE GEOLOGIC OCCURRENCE OF MONAZITE Strong subsurface radioactivity where the top of the Point Lookout Sandstone was intersected at depths of 5,862—5,866 feet, 5,7 51—5,7 57 feet, and 6,360—6,365 feet in three gas wells drilled in the San Juan Basin near Gobernador, Rio Arriba County, Was attributed by Chenoweth (1957, p. 217) to concentrations of heavy minerals similar to those found locally near the top of exposed parts of the sandstone. Three fossil placers are exposed in the top of the Point Lookout Sandstone at Stinking Lake, Rio Arri- ba County (Chenoweth, 1957, p. 216). Two of them seem to be part of the same original deposit. They have an apparent width of 200 feet, length of 2,200 feet, and thickness of 5 feet. The third deposit is ex- posed for a length of about 1,000 feet and is about 5 feet thick. Three small flat-lying erosional remnants of a fossil placer in the Pictured Cliffs Sandstone near Star Lake Trading Post, McKinley County, are about 30‘feet in diameter and 5 feet thick (Chenoweth, 1957, p. 216; Dow and Batty, 1961, p. 34—35). They seem to have been originally much larger. Monazite is a sparse accessory mineral in the heavy-mineral suite at the Star Lake deposit. A fossil placer having an exposed length of 300 feet and thickness of 2—4 feet occurs in the top of the Point Lookout Sandstone on the B. P. Hovey Ranch, Sand- oval County (Chenoweth, 1957, p. 216). Two small poorly exposed fossil placers occur in the Dalton Sandstone Member of the Crevasse Canyon Formation on San Miguel Creek near the center of the Miguel Creek dome, McKinley County (Cheno- weth, 1957, p. 215; Dow and Batty, 1961, p. 35—37). A composite sample from three excavations was analyzed by Dow and Batty and found to contain 4.0 percent of Ti02, 0.4 percent of ZrOz, and 0.03 percent of eTh02. Two small fossil placers have been reported from an area near the Herrera Ranch west of Bernalillo, San- doval County (Chenoweth, 1957, p. 215—216). One is a relict preserved in an area 50 feet wide and 200 feet long in the top of the Gallup Sandstone. It is only 12-14 inches thick, but originally it was appar— ently much thicker and as much as 3 miles long. The other fossil placer is of undescribed size and probably occurs in the Point Lookout Sandstone. FLUVIAI. AND OTHER suancmr. nnrosn's Small amounts of monazite—bearing stream sand and other surficial deposits have been reported from several localities in New Mexico, the earliest reports being those of Day and Richards (1906b, p. 1204—1205) who noted a trace of monazite in black sand from NEW Los Cerrillos, Santa Fe County, and Shandon, Sierra County. At Los Cerrillos the raw sand contains 8 pounds of heavy minerals per short ton, and at Shandon the raw sand contains 40 pounds of heavy minerals per cubic yard (about 28 pounds per short ton). The composition of these concentrates is as follows (Day and Richards, 1906b, p. 1204—1205): Pounds per short ton L03 Cerrillos Shandon Magnetite ______________________________ 1, 088 832 Ilmenite ________________________________ 325 400 Hematite _______________________________ 350 500 Monazite _______________________________ Trace 5 Zircon __________________________________ Trace _______ Quartz _______________________________________ 263 Other minerals __________________________ 237 _______ Gold and platinum _______________________ Trace _______ Total _____________________________ 2, 000 2, 000 The very large amount of hematite is a noteworthy feature of these concentrates: Monazite-bearing black sands have also been re- ported in the area between Tuer and Arroyo, Santa Fe County, and in Pittsburg district, Sierra County (Northrop, 1944, p. 220). At both places the sands contain only a trace of monazite. Sand from the Chama River in Rio Arriba County was stated to con- tain monazite (Jones, F. A., 1915, p. 76; Northrop, 1944, p. 219). The Lost Creek area near San Geroni- mo, San Miguel County, was reported (Uranium Mag, 1955) to contain 4 million short tons of monazite- bearing sand, but an adequate description of the occur— rence was not given. Each of eight samples of heavy minerals from sedi- ments collected by Rittenhouse (1943, p. 17 34—17 35) at evenly spaced intervals across the Rio Grande at Bos- que, Valencia County, contained monazite. The con- centrates consisted of dominant ilmenite, pyroxene, amphibole, epidote, and mica and sparse monazite, tourmaline, zircon, apatite, garnet, sphene, barite, staurolite, kyanite, zoisite, sillimanite, andalusite, ru- tile, and topaz. Monazite was also reported by Bitten- house (1944, p. 166—168) to be sparse, or possibly present, mineral in concentrates from sands of the Rio Grand and its tributaries from San Marcial, Socorro County, upstream to Embuda, Rio Arriba County, and the Chama River at Abiquiu, Rio Arriba County. Par— ticular localities were not cited for monazite. NEW YORK CRYSTALLINE ROCKS A very little monazite( ?) has been identified in crys- talline rocks in the St. Lawrence County magnetite dis- trict in the northwestern Adirondack Mountains (B. 179 YORK F. Leonard, written comun., 1959). Monazite possibly occurs as a disseminated accessory mineral in mag- netite-rich granite gneiss, in skarn, and in garnetiferous quartz rock associated with skarn. Small amounts of'monazite were reported by Mc- Keown and Klemic (1956, p. 11—14) to occur in mag- netite ore of the Old Bed at Mineville, Essex County. The magnetite ore at Mineville occurs in a layered se- quence of complexly folded and highly metamorphosed igneous and sedimentary rocks of Precambrian age. Possibly the rocks are mixtures of Grenville sedimen- tary and igneous intrusives. The lowest unit in the sequence that includes the Old Bed is gabbro. Over- lying the gabbro is the Old Bed magnetite ore, and in succession above the ore granite gneiss grades through diorite into gabbro that is overlain by magnetite ore of the Harmony Bed. The Old Bed magnetite ore contains a gangue of fluorapatite and feldspar, pyrox- ene, and quartz. Monazite, bastnaesite, and hematite commonly occur as inclusions in the fluorapatite, and they also form thin rinds on some of the apatite grains. Magnetite formed later than these minerals, thus, it commonly encloses fluorapatite both with and with- out rinds. The total amount of monazite is not great. Layers of quartz, quartz-sulfide rock, and schistose gneiss in the Carmel Gneiss west of Carmel, Putnam County, contain minor amounts of very radioactive monazite (McKeown, 1951, p. 34). In the Bear Moun- tain area, Rockland County, garnetiferous quartz- feldspar-biotite gneiss was thought by McKeown (1951, p. 13-14) to be monazite bearing. Transparent simple crystals of monazite occur in brown quartz adjoining magnetite-rich layers in coarse-grained sillimanite gneiss at Yorktown Heights, Westchester County (Silliman, 1844, p. 208; Beck, 1850, p. 150; Shepard, C. U., 1852, p. 109; Manchester, 1931, p. 98; Palache and others, 1951, p 695). The locality was described by Bodelson (1948, p. 9084909) as being an outcrop of Manhattan Schist at the Rock- ledge Farm on Hanover Avenue. As exposed, the Manhattan Schist consists of garnetiferous sillimanite- biotite schist, some gneiss, and rare, small pegmatite dikes. Inclusions of magnetite occur in the sillima- nite, and inclusions of monazite occur in the magnetite. Locally the magnetite forms small masses which are penetrated by crystals of sillimanite and contain in- clusions of monazite. Good crystals of monazite are associated with fine- grained sillimanite in amphibole-bearing sillimanite- mica schist at Croton Lake, Westchester County (VVhitlock, 1903, p. 100—101; Manchester, 1931, p. 69). Monazite was reported (Mineral Collector, 1908, p. 90) from several localities in and near the Washing- 180 ton Heights area of upper Manhattan Island, New York City, New York County. Apparently the earli- est of these reports were accounts by Hidden (1888a; 1888b, p. 381) and Chamberlin (1888, p. 220) of mona- zite found by William Niven in the vicinity of 155th Street and Broadway (11th Avenue). The monazite- bearing samples from this locality were reported by Hidden (1888b, p. 381) as also containing tourmaline, apatite, muscovite, orthoclase, zircon, chrysoberyl, xenotime, cordierite, and pinite; but the geologic set- ting of the material was not described. From the min- eral association it would seem that the samples came from pegmatite. Possibly the source was identical with the monazite-bearing pegmatite vein referred by Whitlock (1903, p. 48—49) and Gratacap (1909, p. 139) to a locality at 155th Street and Amsterdam Avenue (10th Avenue), one block east of Niven’s reported sample site. Zircon, xenotime, and garnet are associ— ated with the monazite in the pegmatite at Amsterdam Avenue. Monazite, xenotime, and tourmaline, possibly accompanied by zircon, dumortierite, muscovite, and autunite, were observed in pegmatite in Manhattan Schist exposed at 17lst Street and St. Nicholas Avenue ( 11th Avenue) in Washington Heights (Whitlock, 1903, p. 50—51; Fettke, 1914, p. 234—235). What is probably the same occurrence of monazite, although referred to 17lst Street and Fort Washington Avenue (Hovey, 1895; Baskerville, 1903, p. 466), is a vein of coarse—grained pegmatite in mica schist. The vein is composed of granular gray quartz, orthoclase, and muscovite, and contains several small euhedral trans- lucent crystals of clove—brown monazite associated with xenotime. Monazite closely associated with xenotime and ilmenite was found in oligoclase selvages of a coarse-grained granitic vein in schist and gneiss at 185th Street and the Harlem River (Niven, 1895). CONSOLIDATED SEDIMENTARY ROCKS Detrital heavy minerals in the Tully Limestone of Devonian age exposed between Tully, Onondaga Coun- ty, and Canandaigua Lake, Ontario County, were ex— amined by Trainer (1932, p. 18—29). He found that tourmaline and zircon are the most common heavy minerals in the limestone. They are accompanied by sparse leucoxene and rutile and many exceedingly sparse minerals including augite, plagioclase, mona- zite, apatite, sillimanite, hornblende, garnet, staurolite, hypersthene, ilmenite, magnetite, hematite, and sphene. The monazite occurs as round honey—yellow grains. Their probable source is the metamorphic and igneous rocks of the Canadian Shield and the Adirondack Mountains area, but Trainer emphasized that too lit- tle is known about the distribution of the heavy ac- cessory minerals in the plutonic rocks to permit secure THE GEOLOGIC OCCURRENCE OF MONAZITE identification of the source of the detrital grains by mineralogy alone. Other sedimentary factors, how- ever, including variation in the total abundance of the heavy minerals, thickness of the Tully Limestone, and attitude of the ripple marks tend to indicate that the Adirondack Mountains area was the region from which the heavy minerals derived. If this conclusion is correct, then monazite is evidently a more common accessory mineral in the plutonic rocks of the Adiron— dack Mountains than the literature indicates. BLACK SAND Auriferous black sand of unreported source from Lewis County, N .Y. was described by Day and Richards, (1906b, p. 1204—1205) as containing a trace of monazite per short ton: Pounds per short ton Magnetite _________________________________ 1, 744 Ilmenite ___________________________________ 24 Garnet ____________________________________ 24 Hematite __________________________________ 56 Zircon _____________________________________ 24 Quartz ____________________________________ 24 Other minerals _____________________________ 96 Total ________________________________ 1, 992 BEACH SAND Three samples of beach sand from Long Beach, Nassau County, and West Hampton and Amagansett, Suffolk County, on the south shore of Long Island, were observed by Martens (1935, p. 1594—1595) to contain a very small amount of monazite. An average of the analyses of the heavy-mineral fraction from the three samples showed the following mineralogical composition: Frequency Frequency percent percent Black opaque minerals- 21. 0 Tourmaline __________ 3. 2 Zircon _______________ 1. 1 Garnet ______________ 26. 0 Rutile _______________ . 7 Leucoxene ___________ 6. 5 Epidote ______________ 3. 1 Monazite ____________ . 4 Staurolite ____________ 15. 0 Sphene ______________ . 2 Sillimanite ___________ 2. 4 Hypersthene _________ 7 Kyanite _____________ 2. 5 Andalusite ___________ 7 Hornblende __________ 17. 0 The beach sands are derived from glacial outwash and morainic deposits which were little weathered at the source; hence, the unstable minerals :are fairly abun- dant. NORTH CAROLINA Monazite was first reported to occur in North Caro- lina in 1849 when C. U. Shepard (1849, p. 275; 1852, p. 109) briefly mentioned its association with brookite in the gold placers of Rutherford County. The casual way the observation was made seemingly indicates that the occurrence'was already known, even well known, NO RTE. CAROLINA and Shepard’s remark might also be interpreted to mean that a previous and more formal account of the discovery of monazite in North Carolina had been published, but such is not the fact. No independent evidence for either assumption has been found. For 30 years thereafter scant attention was paid to the oc- currences of monazite in North Carolina because there was no commercial demand for the mineral. A little notice was given it in 1862 and again in 1871 by F. A. Genth. About 1862 Genth found a crystal of mona- zite in auriferous concentrates from Todds Branch in Mecklenburg County (Genth, 1862, p. 204), and in 1871 he wrote that monazite had been reported from gold placers in Rutherford, Burke, and McDowell Counties, but he had not as yet seen it elsewhere than Burke and Mecklenburg Counties (Genth, 1871, p. 81). Industrial interest in the monazite began in 1879 when W. E. Hidden was dispatched by Thomas A. Edison to North Carolina to explore for the ores of rare metals to be used in experiments with illuminating apparatus (Hafer, 1941, p. 291). By 1880, Hidden had dis- covered that monazite was a common detrital mineral in gold placers in parts of Alexander, Burke, Mc— Dowell, Rutherford, and Polk Counties and that it occurred as a rare accessory mineral in mica peg- matites in Mitchell and Yancey Counties (Genth and Kerr, 1881, p. 72—73). On November 20, 1880, Hidden wrote that he had sent to Mr. Edison more than 50 pounds of concentrate from the Captain J. C. Mills gold mine in the Brindletown placer district, Burke County, and that the concentrate contained 60 percent of monazite (Genth and Kerr, 1881, p. 84). This was the first monazite produced in North Carolina and in the United States. During the period 1881 through 1892, interest in monazite in North Carolina continued to grow. This growth is evidenced by the publication of descriptions of concentrates from Burke County (Mallet, 1882, p. 205; Am. Naturalist, 1883, p. 313; Dana, E. S., 1882, p. 247—248) and analyses of monazite and monazite sand from the Brindletown district in Burke County (Penfield, 1882, p. 251; Dana, 1884, p. 542; Eng. and Mining Jour., 1888, p. 2), by a display of monazite from Alexander County at the New Orleans World’s Industrial and Cotton Centennial Exposition of 1884— 85 (Hidden, 1885, p. 183), by the discussion of the oc- currence of monazite in Alexander County (Bath, 1886, p. 149-150; Hidden, 1888b, p. 381) and Mitchell County (Phillips, 1888, p. 398), and by the discovery of monazite in pegmatites at Zirconia, Henderson County, and at Mars Hill in Madison County (Hid- den, 1888b, p. 381; Genth, 1891, p. 78). From 1881 through 1885, monazite apparently was not mined in 181 North Carolina. In 1886, mining began in the Brin- dletown gold placer district, and in 1887, the district furnished 12 short tons of monazite concentrate. From 1888 through 1892 a combined output of a few short tons of monazite was achieved annually at Brin- dletown and several neighboring areas from small hand-mining operations, but the sources and quanti- ties were not recorded (Nitze, 1895a, p. 689; Pratt, 1902, p. 61; 1903, p. 183; Schaller, 1922, p. 4, 11). Records begun in 1893 show a sustained production of monazite in North Carolina through 1910 with a small and intermittent output through 1917 (see table 30). The abrupt fall in production during 1896 and 1897 re- flects the introduction in 1895 of large quantities of Brazilian monazite into world commerce (Dennis, 1898, p. 487 ; Sci. Am. 1899; Pratt, 1902, p. 61; Mining and Sci. Press, 1902; Eng. and Mining Jour., 1906c, p. 713), and the demise of the industry was brought about by the start of monazite mining in India (Meis- ner, 1929, p. 234; Houk, 1946, p. 11—12; Roots, 1946, p. 50). Despite a report that monazite was practically ex- hausted in the North Carolina deposits by 1897 (Nitze, 1897, p. 131—132), the reserves were conservatively es- timated in 1915 as 15,000—20,000 short tons of mona- zite (Kithil, 1915, p. 19), and when mining ceased there was said to be an abundance of monazite in the streams (Schaler, 1919, p. 156). Abandonment of the placers was caused by a decline in the price of mona- zite, not by a lack of the mineral. The period of greatest activity in the commercial exploitation of monazite in North Carolina was also a time of increase in the literature on the deposits, and a contemporary bibliography lists 44 papers on monazite in North Caro- lina by 1909 (Laney and Wood, 1909, p. 403). Several times between 1917 and 1960 renewed inter- est in domestic sources for monazite has led to mining activity in North Carolina. Between 1929 and 1936 some prospecting and development were done in Burke and Cleveland Counties, but even in the depression years monazite could not be mined in competition with the imported mineral (Bryson, 1937, p. 132). A pre- liminary field investigation of 23 monazite deposits in Rutherford, Burke, and Cleveland Counties, N. C., and Cherokee County, S. C., was made early in World lVar II by the Regional Products Research Division of the Tennessee Valley Authority. Results of the investigation showed that these domestic sources could serve as a substitute for Brazilian and Indian monazite under conditions of critical short supply (McDaniel, 1943; Lefl'orge and others, 1944). Between 1945 and 1954 considerable work was done on the oc— currence of monazite in the Southeastern States, in- 182 cluding North Carolina, by the U.S. Geological Survey and US Bureau of Mines, in part sponsored by the U.S. Atomic Energy Commission (Broadhurst, 1955, p. 7 9-80). Field parties of the U.S. Geological Survey delineated the regional distribution of monazite in crystalline rocks (Mertie, 1953, pl. 1), showed the local distribution of monazite in schists and gneisses (Over— street, Yates, and Griflitts, 1963a), appraised fluvial placers in the western Piedmont province (Overstreet, Theobald, and Whitlow, 1959), and made a reconnais- sance of the occurrence of monazite in sedimentary rocks of the Coastal Plain province (Dryden, 1958, p. 398—401). Activity by the U.S. Bureau of Mines con- sisted of drilling fluvial placers in the western Pied- mont province at locations recommended by the U.S. Geological Survey (Griffith and Overstreet, 1953a, b, c; Hansen and White, 1954; Hansen and Cuppels, 1954). The resources in monazite in tributaries to the Broad River and southern tributaries to the Catawba River in North Carolina comprising placers in Cleve- land, Rutherford, Polk, McDowell, Burke, Catawba, and Lincoln Counties were estimated to be at least 490,000 short tons (Overstreet, Theobald, and Whit- low, 1959, p. 713). During 1951 through 1953 several private companies explored monazite placers in the western Piedmont province of North Carolina, and one organization opened a placer and constructed a separa- tory plant on the upper part of the First Broad River between Carson Mountain and Richland Mountain in Rutherford County. The venture operated for 1 or 2 years, and produced some monazite during 1953 (Councill, 1955, p. 6). There was no other recorded output of monazite in North Carolina between 1917 and 1960. In the late 1950’s mineral collectors showed interest in the placers (Allen, Fred, 1958; Allen, Mrs. Fred, 1958, p. 328; Yedlin, 1958, p. 419; Zodac, 1958). As early as 1893, occurrences of placer monazite were known in Burke, Cleveland, Rutherford, Catawba, Gaston, Lincoln, McDowell, Polk, and Mecklenburg Counties, and by 1908 the known distribution of placer monazite had been extended to Alexander, Caldwell, Clay, Iredell and Wilkes Counties in North Carolina (Mezger, 1895, p. 822; 1896; Nitze, 1897, p. 129; Pratt, THE GEOLOGIC OCCURRENCE OF MONAZITE 1908, p. 61; Sterrett, 1908b, p. 274; 19080, p. 72—73; Pratt and Sterrett, 1908a, p. 315; 1908b, p. 63; Pratt and Berry, 1911, p. 72~81). The first three of these counties were probably the main sources of monazite during the 1890’s, but records prior to 1900 give scant information on the relative positions of the counties as producers. Cleveland County seems to have been a leading source for monazite during 1898 and 1899 (Sci. Am., 1899). In 1902 and 1905, monazite was shipped from Burke, Cleveland, Lincoln, McDowell, and Rutherford Counties (Pratt, 1904a, p. 15; 1904b, p. 1164; 19040, p. 35; 1907a, p. 41), and in 1915 through 1917, it came mostly from Burke, Cleveland, Iredell, Lincoln, and Rutherford Counties (Pratt and Berry, 1919, p. 104—105), but their rank as producers is not known. Burke, Cleveland, and Rutherford Counties were the main sources of monazite between 1900 and 1907 (table 58). The source of the monazite was Recent alluvium and colluvium in the valleys of small streams, except at two places in Cleveland County where efforts were made beginning in 1900 to mine monazite from weath- ered crystalline rocks (Pratt, 1901, p. 31; D’Allier, 1906, p. 30; Kithil, 1915, p. 19; Levy, S. I., 1924b, p. 80.) The only deposits that were successfully worked for monazite were the stream placers and associated colluvium on the valley sides (Mining Jour., 1894; Graton, 1906, p. 117; Bohm, 1906; Schaller, 1919, p. 156; Hess, 1937b, p. 524). Monazite was mined by hand methods in a small way, commonly as part-time or off—season work by the landowners themselves. The stream beds were narrow and shallow. At most of the mines the thickness of the alluvium, including over- burden, was only 1—8 feet, and the valley floors were seldom more than 100 or 200 feet wide and 300 feet to a mile in length (Sterrett, 1908b, p. 280; Pratt and Sterrett, 1908a, fig. 4; 1909; Santmyers, 1930, p. 10). In some valleys the placers were mined for a distance of a mile or two, and along many small streams the creek beds were mined several times a year because they were replenished following heavy rains by run— off which brought in monazite from cultivated fields on the adjacent hillsides (Graton, 1906, p. 117 ; TABLE 58.—Relative rank in production of monazite-producing counties in North Carolina by years of available data, 1900—1907 [Ranked annually in numerical order of decreasing production, leading county numbered 1] Reference (Pratt) Alexander Burke Catawba Cleveland Iredell Lincoln McDowell Polk Rutherford Date Page 1 900 ____________________________ 2 ________ 1 ________________________________ 3 1 901 3 1 1 901 ____________________________ 1 ________ 2 ________________ 3 ........ 4 1 902 61 1903 ____________________________ 3 ________ 4 ________ 5 2 ________ 1 1904b 35 1 904. ____________________________ 2 ________ 1 ________ 5 3 ________ 4 1 905 46 1 906 ____________________________ 3 7 1 8 5 4 6 2 1 907b 1 22 1907 ____________________ 5 3 6 l 4 ________________________ 2 1 908 66 NORTH CAROLINA Sterrett, 1908b, p. 280; Pratt, 1916, p. 49). In Cleve- land County, monazite was recovered from weathered biotite gneiss rich in pegmatite exposed :at the work- ings of the British Monazite Co. on Hickory Creek about 3 miles northeast of Shelby and at the F. K. McClurd mine about 0.75 mile northeast of Carpenter Knob (Sterrett, 1908b, p. 281). At both localities the monazite content of the gneiss proved to be very vari- able, ranging from 0.03 to 1.1 percent of the weight of the weathered rock. The ventures failed because suf- ficient high-grade ore could not be obtained. Monazite was virtually the only product from the North Carolina placers. A small amount of gold was recovered from some placers in Cleveland County (Pratt and Sterrett, 1909; Pratt, 1914, p. 19), and similar small output doubtless was achieved also in parts of Burke, McDowell, and Rutherford Counties. There seems to have been some interest in the market— ing of accessory garnet for use as an abrasive, and some was shipped, but it was either rejected or sold at low prices because it was unsuited in size and shape to the demands of the trade (Pratt, 1908, p. 66; Keith and Sterrett, 1931, p. 13). The monazite in the form of small batches of rough concentrate was generally carted from the mines to local cleaning plants where the concentrate was sold by the miners at prices governed by the monazite con- tent. At the cleaning plants the rough concentrate, which consisted of a complex group of minerals (Boudouard, 1898, p. 11) in which ilmenite, garnet, zircon, sillimanite, tourmaline, and rutile were most common but which locally contained upwards of 100 varieties of minerals (Eng. and Mining Jour., 1896) were processed into shipping grade monazite sand. This product has been variously described as contain- ing 66 percent of monazite (Barker, 1903, p. 165), 65— 70 percent of monazite (Chemische Zeitschr., 1906), 80 percent or more of monazite (Franklin Inst. J our., 1908, p. 318), and 92—95 percent of monazite (Ladoo, 1925, p. 396). The thorium oxide content of the rough concentrate from the mines was very variable owing to differences in the amount of monazite in individual batches of concentrate and to variations in the abundance of thorium oxide in the monazite itself. Several old an- alyses of these concentrates were published. Some have been called analyses of monazite, but they are an- alyses of mixtures of monazite and other minerals. Nine samples of monazite sand containing as much as 67 percent of monazite and from unspecified localities were reported by Nitze (1895b, p. 21) to have 0.125, 0.175, 0.225, 0.26, 0.29, 0.40, 1.27, 3.40, and 5.19 percent of Th02. Concentrates from known localities were 183 reported by Pratt (1902, p. 60; 1903, p. 182) to con- tain from 1.27 to 7.28 percent of ThOZ: Th02 Burke County: $3) -White Bank gold mine- _ _ _ _ -_ _- _________________ 2. 15 Hall Creek _____________________________________ 2. 25 Linebacher place, Silver Creek ____________________ 6. 54 Locality unknown ______________________________ 7. 28 McDowell County: Long Branch ___________________________________ 1. 27 Alexander Branch _______________________________ 6. 30 MacLewrath Branch ____________________________ 2. 48 Cleveland County: Proctor farm, Belwood __________________________ 5. 87 Wade McCurd farm, Carpenter Knob _____________ 6. 26 Davis mine, Mooresboro ________________________ 3. 98 Concentrate from weathered rock _________________ 7. 01 Rutherford County: Near Henrietta _________________________________ 1. 93 Complete analyses of low—thorium oxide Carolina monazite sand show the following composition: [Analystsz A. Boudouard (1898, p. 12); B, Chernik (1908, p. 250)] Percent A. B CeOz ___________________________________ 12. 50 1 45. 40 Di203 +La203 ___________________________ 8. 07 6. 56 Y203 (group) ____________________________ . 48 2. 07 ThOZ ___________________________________ 2. 42 1. 22 P205 ___________________________________ 39. 48 23. 43 SiOz ____________________________________ 9. 56 1. 60 A1203+ E6203 _____________________________ 9. 85 2 11 69 Ti02 ___________________________________ 6. 63 _______ ZrOz ___________________________________ 5. 75 3. 25 Nb205+ T3205 ___________________________ 4.12 ....... MgO ___________________________________ 3. 74 _______ H30 ____________________________________ . 20 _______ Other oxides ____________________________ (3) (‘) Insoluble residue _________________________ 1. 55 _______ Total _____________________________ 100. 23 99. 34 1 Cean. 2 A1203, 2.49; Fezos, 5.58; FeO, 3.62. 3 09.0 trace; B8201, trace. ‘ Mud, trace. After upgrading at the cleaning plants, the shipping product was said to have had variously 4 percent of T1102 (Barker, 1903, p. 165), 5 percent of T1102 and. 0.43 percent of U308 (Boltwood, 1905, p. 607—608; Pratt, 1905, p. 41), 3—9 percent of Th0; (Fleck, 1909, p. 205), 5—6 percent of T1102, and 61—62 percent of RE203 (Kremers, 1958, p. 2). As in the reports on the tenors of the crude concentrates, there is an increase in the amount of thorium oxide in the product as the industry improved its methods of preparing concen- trates, and the product shipped in the last years of mining was more nearly pure monazite and thus con- tained more thorium oxide than the product sold in the early years. A concentrate consisting of nearly pure monazite milled in 1943 was reported to contain 7 percent of Th0.» (McDaniel, 1943). 184 An analysis of helium-bearing monazite from an unspecified locality in North Carolina was reported by Thorpe (1895) to show 18.01 percent of Th02 and 1.62 percent of Sn02, but the amount of helium was not given: Percent 08203 _____________________________________ 25. 98 118.203 _____________________________________ 23. 62 Th0; ______________________________________ 18. 01 P205 ______________________________________ 28. 43 $1102 ______________________________________ 1. 62 CaO _______________________________________ . 91 MnO ______________________________________ 1. 33 Total ____________________________________ 99. 90 Among the many analyses of monazite from Carolina that have subsequently been made, none discloses as much thorium, and among analyses of monazites from the United States only an old one of material from pegmatite at Amelia Court House, Va., and a recent one of monazite from pegmatite at Yucca Valley, San Bernardino County, Calif., have more than 18 percent of Th02. The large quantity of tin is also most unusual for North Carolina monazite. Other early descriptions of monazite from North Carolina mentioned that it contains helium and is radioactive (Barker, 1903, p. 164—165; Strutt, 1904, p. 193; Boltwood, 1905, p. 611), discussed the presence of thorium and rare earths (Hutchinson, Arthur, 1909, p. 214—215; James, 1913, p. 238), and showed that monazite displays neither fluorescence nor phospho- rescence if subjected to ultraviolet radiation (Basker- ville, 1903, p. 466)? Detailed analyses of purified samples of monazite from North Carolina were made as early as 1882 (Penfield, 1882, p. 252), and others were recorded in- termittently through the life of the monazite industry. A spate of analyses was introduced during the late 1930’s as a result of an interest in using radioactive minerals to study geologic time. In the 1940’s and early 1950’s scores of analyses were made when there was a revival in demand for monazite as a source for thorium. These analyses are given farther along in the text where individual localities are discussed. HYPOTI-IESES 0F ORIGIN The origin of monazite in the crystalline rocks of North Carolina received scant attention during the life of the industry. Monazite in granitic rocks and peg- matite was interpreted to have formed as a primary nMurata and Bastron (1956) showed that monazite and other transparent cerium-earth minerals strongly absorb the violet, blue, and yellow radiation from an unfiltered medium-pressure mercury- vapor lamp and transmit the green radiation, with the result that the mineral assumes the emerald-green color of the unabsorbed radia- tion. THE GEOLOGIC OCCURRENCE OF MONAZITE accessory mineral, whereas that in schists and gneisses was attributed to impregnation from the granitic intrusives (Mezger, 1895, p. 823; Nitze, 1897, p. 128; Pratt, 1903, p. 180—181; Graton, 1906, p. 117; Pratt, 1907b, p. 113; Sterrett, 1908b, p. 284—285; Pratt and Sterrett, 1909). The absence of monazite from parts of the State most widely underlain by granitic rocks was not at that time recognized, probably because suit- able geologic maps were lacking; hence, the apparent conflict between the postulated origin and the spatial distribution of the monazite was not perceived. The beltlike extent of the monazite—bearing area in the western Piedmont of North Carolina was recog- nized in the early 1900’s and the opinion was expressed that the trend would persist for many miles toward the northeast and southwest beyond the then-known limits near Wilkesboro, NC, and Anderson, SC. (Pratt, 1907b, p. 109; 1916, pl. 1). After the close of the industry in 1917, further exploration for monazite was halted until 1945 when Mertie began to study the distribution of monazite in the crystalline rocks of the Southeastern States. Mertie (1953, pl. 1) was able to show that the early predictions about the probable extent of the monazite belt in the western Piedmont were correct and that the belt extended at least to Fredericksburg, Va., and to the Coosa River, Ala. For all this additional extent, only Surry County, NC, was added to the group of known monazite-bearing counties in the western Piedmont of North Carolina. In the eastern part of the State, however, a previously unknown linear zone of monazite-bearing crystalline rocks was discovered by Mertie (1953, pl. 1) in War- ren, Franklin, and Wake Counties. This belt con- verges northward to the western Piedmont belt in Vir- ginia. Later, Mertie found another linear zone of monazite—bearing crystalline rocks in the Blue Ridge in the western part of the State (Mertie, 1957). The Blue Ridge belt extends into Virginia and Georgia. The localized occurrence of monazite in belts was seen by Mertie to be a fundamental factor in the origin of monazite in the Southeastern States. In his explanation for the distribution of monazite, of which only a preliminary statement and slight re— vision (Mertie, 1953, p. 29—30; 1958, p. 4) were avail- able as of 1962 when this review was written, the belts were interpreted to be the sites of Precambrian sedimentation, not necessarily active at the same time, in which concentrations of detrital monazite were formed as old Precambrian monazite—bearing source rocks were eroded. These sedimentary rocks and the contained monazite placers were later recon~ stituted by heat and pressure into metamorphic rocks. Some of the sedimentary material, and possibly some NORTH CAROLINA of the monazite-bearing source rocks, were locally melted to form monazite—bearing intrusive rocks. The three belts include various kinds of crystalline rocks of which many do not contain monazite. The belts are not geologic formations, and they cut across the strike of known stratigraphic units. They are inferred to be the traces of the monazite—enriched sedimentary basins, and the grains of monazite are inferred to be mainly relict detrital particles that have withstood the metamorphism (Mertie, 1953, p. 29—30). Accessory ilmenite and magnetite were thought by Mertie (1953, p. 30) to have had somewhat equal abundance in most of the early Precambrian source rocks from which the monazite-bearing sediments were derived. During the sedimentary cycle or cycles through which the detrital monazite passed, a par- tition is thought to have taken place in the relative abundance of accompanying detrital ilmenite and magnetite because ilmenite is much more abundant than magnetite in the monazite-bearing metasedi- mentary rocks. Presumably magnetite was eliminated from the sedimentary rocks prior to metamorphism by the well-known tendency of magnetite to oxidize and be destroyed during weathering and transport. Under the same conditions, ilmenite was more stable than magnetite; therefore, loss of magnetite was ac- companied by relative increase in ilmenite. After long—continued weathering ilmenite also tended to be removed from the natural heavy-mineral suite of the sedimentary rock. This partition during the sedi- mentary cycle resulted in the development of three distinct nongradational types of heavy—mineral suites. These are an ilmenite-rich type, a type lean in both ilmenite and magnetite, and a scarce type rich in magnetite. The common ilmenite-rich type of mona- zite concentrate is interpreted to be a typical placer assemblage in which relict stable detrital ilmenite ac- companies relict detrital monazite in the metasedi- mentary rocks. Monazite concentrates of the type lean in ilmenite and magnetite are interpreted to have come from sedimentary rocks which had undergone long periods of weathering during one or more sedi- mentary cycles. The scarce, magnetite-rich type of monazite concentrate was ascribed to rocks formed in local remobilized zones in the original Precambrian monazite-bearing source rocks. The dominant con- cept of this interpretation is the persistence of original detrital heavy minerals from the sedimentary cycle through the metamorphic cycle and the control their original basins of sedimentary deposition exerts over the present geographic distribution of the mona- zite-bearing rocks. 238—813—67—13 185 The location as shown by Mertie of the belt of monazite-bearing crystalline rocks in the western Piedmont was used by the writer and his associates between 1951 and 1954 as a guide in a program of sampling fluvial placers. About 4,200 concentrates were panned from stream sediments, and the con- centrates were examined mineralogically in the lab- oratory of the US. Geological Survey by a staff under Jerome Stone. The results of this work (Over- street, Theobald, and others, 1956; Overstreet, Theo- bald, and Whitlow, 1959, p. 7 09—710) showed that the actual boundaries of the Carolina segment of the belt were Virtually the same as the boundaries drawn by Mertie from reconnaissance. Other results in agree- ment with Mertie’s observations were that the belts cut across stratigraphic units, that they were formed at different times, and that the abundance of mona- zite increases in areas where ilmenite dominates over magnetite. In this work, however, and in earlier and later studies, the writer and his coworkers discovered several facts and noted previously uncorrelated ob- servations that bore on the origin of monazite and led to an interpretation fundamentally different from the one given by Mertie. This interpretation pro- poses that the belts of monazite—bearing metasedi- mentary rocks define zones of regional metamorphic climax in which much of the monazite originated as a metamorphic mineral derived from components available in normal shale and sandstone and that detrital concentration of monazite in the original sediments is not a precondition for the localization of the belts. The belts were thought to have formed during three orogenic events in the southern Appa- lachians, and each belt is associated with a different culmination This interpretation is thought to pro- vide a basis for predicting the occurrences and com- position of monazite in crystalline rocks elsewhere in the world. The general aspects of the interpretation have been presented previously in this and other re- ports (Overstreet, 1960), and the details are given elsewhere; however, a summary as it applies to the Southeastern States is an appropriate introduction to a discussion of monazite in North Carolina. A regionally concordant trend and direct relation were found in the monazite belt in the western Pied- mont between the abundance of monazite in present sediments of small streams and the abundance of as- sociated sillimanite, almandine, ilmenite, and rutile. A regionally concordant trend and inverse relation were found between the abundance of monazite and that of staurolite, kyanite, epidote, and magnetite. The abundance of monazite increases in these fluvial sediments as the abundance of sillimanite, almandine, 186 ilmenite, and rutile increases and as the abundance of staurolite, kyanite, epidote, and magnetite decreases. Inasmuch as these small streams drain saprolite and residual soil, the striking antipathetic relations be- tween the two groups of minerals were interpreted to reflect conditions of regional metamorphism in the underlying crystalline rocks (Overstreet and Grifiitts, 1955, p. 555; Overstreet, Cuppels, and White, 1956, p. 595—596; Overstreet, 1962, p. 158-162). Sillimanite, a1- mandine, ilmenite, and rutile are associated in meta- morphic rocks of the sillimanite-almandine subfacies of the amphibolite facies (Turner, F. J ., 1948, p. 81— 87). Staurolite, kyanite, epidote, and magnetite occur in rocks of lower metamorphic facies. The regionally concordant trend and direct relation between the abundance of monazite and the minerals formed by high-grade regional metamorphism were interpreted by the writer and his associates to indicate that the major geologic control of the distribution of monazite was increasing grade of regional metamorphism. Details of the variation in the abundance of mona- zite related to the kind of crystalline rocks in the monazite belt in the western Piedmont were examined by R. G. Yates and others in the Shelby quadrangle, Cleveland and Rutherford Counties. Geologic map- ping showed that the quadrangle was underlain by thick sequences of sandstone, graywacke, and shale with sparse interbedded felsic volcanic rocks, which were isofacially metamorphosed at the upper amphi- bolite facies (Overstreet, Yates, and Griffitts, 1963b). The metamorphosed stratified rocks consist princi- pally of biotite schist, sillimanite schist, and biotite gneiss which respectively underlie 62 percent, 30 per- cent, and 1 percent of the area of the quadrangle. These rocks were intruded by synkinematic quartz monzonite, which underlies 7 percent of the area of the quadrangle. The distribution and abundance of monazite in the crystalline rocks were determined by examining panned concentrates from 1,241 samples of saprolite. Monazite was found to be most fre- quently present and most abundant in the quartz monzonite, pegmatite, and sillimanite schist. It was found to be least commonly present and least abun- dant in the biotite schist. Contours drawn on a map of the Shelby quadrangle to show the abundance of monazite in the isofacial metasedimentary rocks dis- closed a consistent pattern of low percentages that occupy the main areas underlain by biotite schist and high percentages that occupy the principal zones underlain by sillimanite schist (Overstreet, Yates, and Griffitts, 1963a, pl. 1). Other evidence, although indirect, also indicates that the sillimanite schist is the preferred host for THE GEOLOGIC OCCURRENCE OF MONAZITE monazite among the metasedimentary rocks. An air- borne radioactivity survey of the northern part of the Shelby quadrangle disclosed that radioactivity highs resulting from monazite in residual soils form over sillimanite schist, and lows form over biotite schist (Overstreet, Meuschke, and Moxham, 1962). Several eU analyses of bulk samples of rocks from the Shelby area show that sillimanite schist is about three times as radioactive as biotite schist (W. R. Griflitts, written c0mmun., 1954): [Analyst: J. Patton, 1953] Number eU of samples (ppm) Sillimanite schist __________________________ 1 30 Biotite schist ______________________________ 2 10 Biotite gneiss ______________________________ 4 10 Pegmatite ________________________________ 1 40 The original sedimentary materials from which the sillimanite schist was derived were interpreted by Overstreet, Yates, and Griffitts (1963b) to have been fine grained and aluminous. Most likely they were shale and mudstone; this possibility is supported by the extreme scarcity of zircon in the schist. Zircon was absent from 84 of 150 samples of sillimanite schist, was present as a trace in 41 samples, and av- eraged only 0.0006 weight percent in 25 samples (Overstreet, Yates, and Griffitts, 1963a, table 1). Monazite, however, was absent from only 12 of the 150 samples, was present as a trace in 28 samples, and averaged 0.002 percent of the rock in 110 samples. The original sedimentary materials from which the biotite schist formed were interpreted by Overstreet, Yates, and Griflitts (1963b) to have been graywacke and sandstone. Zircon is more common in the biotite schist than it is in the sillimanite schist, just as it is more common in sandy sediments than in shales and mudstone. Zircon was absent from 40 of 198 samples of biotite schist, was present as a grain or two in 46 samples, and averaged 0.001 weight percent in 112 samples (Overstreet, Yates, and Griflitts, 1963a, table 1). An almost identical distribution was found for monazite. Of the 198 samples of biotite schist, mona- zite was absent from 49, was present as a trace in 42, and averaged 0.001 percent in 107 samples. Detrital monazite and zircon are much less common in clay- and silt-sized sediments than they are in sand-sized sediments, as has been shown in the many studies of sedimentary rocks cited through this report. In view of the sparseness of zircon in the sillimanite schist and of the tendency for fine-grained sediments to be similarly impoverished in detrital monazite, it is improbable that the monazite in the sillimanite schist consists of relict detrital grains. Evidently separate factors control the presence of zircon and monazite in this rock. NORTH CAROLINA 187 TABLE 59.—Abundance of monazite in crystalline rocks in the monazite belt in the western Piedmont province including estimates of the contribution of the monazite to the thorium in the rock Rock 1 (and number of samples) Average abundance of Th02 North Carolina: Shelby quadrangle: 1. Sillimanlte schist.._. .. Maximum (of 1 am Average (of 110)... 2. Biotite schist, Shelby quadrangle Maximum (of 198) Average (of 107).- - _..- 3. Biotite meiss Maximum (0! 59) .............................................................. Average (of 47) ....... 4. Toluca Quartz Monzonite ..... Maximum (0196) Average (of 93).. 5. Microcline-oligc ‘ quartz peg-m mm Maximum (of 329) Average (of 289) ............................................................... Georgia: 6. Granite south of 7mm“ Southeastern States: 7. All monazite-bearing granitic rocks. - . m monazite Monazite in Th in monazite rock as ppm of the (percent 1) Number of rock analyses in percent 2 average _ """""" 55:5 . 9 """"""" if; ._. . 5 """""" ééfi ........... 2. 8 """""" iii; 2. 1 .--..-...IZIZI ‘ """""" an ____________________ 3. 3 - 6. 6 3. 0 1 Items 1—5 recalculated to weight percentage from volume percentage given by Overstreet, Yates, and Griffitts (1963a). Items 6 and 7 from Mertie (1953, p. 15 and ). 2 Thorium oxide in items 1—5 determined by K. J. Murata and H. J. Rose, Jr. The lesser average abundance of monazite in the biotite schist compared to its average abundance in sillimanite schist is a reversal of the normal distri- bution of detrital monazite in shales and sandstones. The near identity in the average abundances of mona- zite and zircon in the biotite schist is unusual because sandstones rarely contain these minerals in equal amounts. The amount of monazite in the metamorphic rocks (table 59), as reported by Mertie (1953, p. 15, 29) and Overstreet, Yates, and Grifiitts (1963a, table 1), does not indicate general placer concentration of heavy minerals in the sedimentary rocks. Average tenors of 0.001—0.006 percent of monazite in the crystalline rocks are an order of magnitude less than the tenors of marginal fluvial monazite placers containing about 1 pound of monazite per cubic yard of sediment. Such tenors are five orders of magnitude less than the concentrations of monazite found in beach placers like those in Brazil and India. When the amount of thorium in the monazite is recalculated as thorium in the metamorphic rock (table 59), it is seen that the thorium contributed by the monazite is less than one-tenth of the average amount of thorium in shale, graywacke, and sand- stone. Therefore, the amount of monazite in the original sediment was not enriched by placer concen- tration. The monazite-bearing samples of sillimanite schist contain an average of only 0.9 ppm of Th attrib- utable to thorium in monazite, and the average attrib- utable to monazite in biotite schist is only 0.5 ppm. The average shale has about 12 ppm of Th; the aver- (in Overstreet, Yates, and Grifiitts, 1963a, table 4); in items 6 and 7 determined by F. C. Grimaldi and associates (Mertie, 1953, p. 12). 3 lfietgrlmined on detrital monazite from streams in the region; therefore, not strictly app ca e. age graywacke may contain about the same amount as or less than the shale; the average sandstone probably has between 2 and 24 ppm of Th with possibly an aver- age of 5.4: ppm (Adams and Weaver, 1958, p. 4:02, 413; Murray and Adams, 1958, p. 265; Rankama and Sa- hama, 1950, p. 573). The amount of thorium (and uranium) contributed by the monazite is also inade- quate to account for the equivalent uranium deter- mined for the samples of schist. Presumably, the indicated deficiency in thorium attributable to mona- zite compared to average amounts found in shales and sandstones is compensated by thorium in minerals like mica and garnet and by thorium in intergranular films in the metamorphic rocks. The greater abundance of monazite in the meta- morphosed shale and its greater radioactivity com- pared to the metamorphosed sandy sediment seems to correspond to the original distribution of thorium in the sedimentary rocks instead of to any original presence of detrital monazite. Very little of the thorium in common sand was said to be associated with heavy detrital minerals, and common sands con- tain only from one-twentieth to one-third as much thorium as shale. Offshore shales contain more thorium than nearshore sands and beach sediments (J afi'e and Hughes, 1953; Breger, 1955, p. 63; Adams and Weaver, 1958, p. 396—399, 412—413; Murray and Adams, 1958, p. 263, 267—268; Adams and others, 1958, p. 272). If the monazite in the metamorphic rocks is interpreted to be a metamorphic mineral formed from components available in the sediment and if the facies of metamorphism and concentration 188 of components is interpreted to control the rate of nucleation of monazite during metamorphism, then the abundance of monazite should be greatest in those metamorphic rocks that initially had the most thorium and other necessary components and were metamorphosed to the highest facies. For these reasons shale metamorphosed t0 sillimanite schist has more monazite than isofacial biotite schist derived from sandstone and graywacke. Also for these rea- sons sillimanite schist throughout the world com- monly contains minor accessory monazite, although shale usually lacks detrital monazite. Specific stratigraphic units of shale or sandy sedi- ment do not control the shape and trend of the mona— zite belt in the western Piedmont. The belt cuts across stratigraphic units. These relations indicate that specific sedimentary units possessing unique abundances of detrital minerals are not requisite for the formation of the belt but that some process oper- ating later than the sedimentation produced it. Zones of regional metamorphism have been shown to cut across stratigraphic units in the Carolinas (Over— street, Yates, and Griffitts, 1963a; Overstreet and Bell, 1960, 1962, map), and the metamorphic zone of highest facies in the western Piedmont was found to be coextensive with the monazite belt (Overstreet, 1962, p. 158—161). The trend of the belt athwart the strike of stratigraphic units is interpreted to result from the crystallization of monazite in the parts of the sedimentary rocks that were brought to the high- est metamorphic facies. Systematic regional variations in the abundance of thorium oxide in monazite from the metasedimentary rocks also indicate that the monazite formed during metamorphism. The average abundance of thorium oxide in monazite from the sillimanite schist and isofacial biotite schist in the western Piedmont is 4.80 percent, which is about the minimum usually associ- ated with monazite from metamorphic rocks of this facies (Overstreet, 1960, p. B56). Monazite from streams underlain by rocks of the staurolite—kyanite subfacies along the flanks of the belt contains some- what less thorium oxide than does monazite from sillimanite schist. Six samples of monazite from streams in this environment in North Carolina aver- age 4.32 percent of ThOZ. Relict detrital grains of monazite are not likely to have been sorted into the original sedimentary rocks in such a way that their composition would vary areally and sympathetically with later progressive regional metamorphism. Monazite from the synkinematic quartz monzonite emplaced in the schists during the main regional THE GEOLOGIC OCCURRENCE OF MONAZITE metamorphism contains an average of 6.1 percent of ThO2 in 23 samples (Overstreet, Yates, and Griffitts, 1963a, table 4). An identical average abundance of thorium oxide was found for 43 samples of monazite from pegmatite genetically related to the quartz mon- zonite. This amount of thorium oxide resembles the lower part of the range in abundance found for monazite from granitic rocks associated with meta- sedimentary rocks at the sillimanite-almandine sub- facies (Overstreet, 1960, p. B56). Similarly, the relict detrital origin of magnetite in the monazite belt in the western Piedmont is contra- indicated by systematic variations in trace elements. Magnetite from the sillimanitic core of the monazite belt has more lead, copper, tin, titanium, antimony, and beryllium, and less manganese and zinc than magnetite from the lower—grade metamorphic zones on the flanks of the belt (P. K. Theobald, J r., written commun., 1961). The apparent age of individual minerals from rocks in the monazite belt in the western Piedmont indicates that the major pulse of regional meta— morphism during which the monazite was formed probably took place in Ordovician time (Overstreet, Bell, and others, 1961, p. B105). During this episode the monazite-bearing synkinematic quartz monzonite was emplaced. Subsequently, the rocks of the Pied- mont were again metamorphosed, probably in Car- boniferous time, and crosscutting masses of granitic rocks were locally intruded along the margins of the monazite belt in the western Piedmont. At a very few places these young masses of granite have been found to contain minor accessory monazite accompanied by copious accessory magnetite and variably present allanite, sphene, and epidote (Dietrich, 1961, p. 9—12). These accessory minerals, except monazite, are present in very few places in the older synkinematic quartz monzonite at the core of the belt (Overstreet and Griflitts, 1955, p. 565—566), but they are characteristic of monazite-free granitic rocks between the western and eastern monazite belts in South Carolina (Overstreet and Bell, 1962) and presumably are equally common in central North Carolina. Locally, the young crosscutting granitic intrusives at the margin of the western monazite belt are nearly devoid of heavy accessory minerals. The monazite from only one of these late bodies of granite has thus far been analyzed. It is unusually rich in uranium, containing 2.34 percent of U308, an amount greater than any previously reported for monazite from the United States. It also is rich in thorium oxide; the average of three analyses is 6.6 percent of NORTH CAROLINA Th02 (Overstreet, and Griffitts, 1963a, table 4). The occurrences of monazite in the Blue Ridge belt and in the belt in the eastern Piedmont are also as- sociated with narrow zones of sedimentary rocks metamorphosed to the upper amphibolite facies, but neither of these belts displays as broad and persistent a zone at this facies as the belt in the western Pied— mont. In the Blue Ridge belt, sillimanite is known in discontinuous bands from Clay County on the border between North Carolina and Georgia at least as far northeastward as Mount Mitchell in Yancey County (Hash and Van Horn, 1951, pl. 9, p. 18, 36). For the Blue Ridge belt as a whole, however, most of the monazite-bearing metasedimentary rocks are at the staurolite—kyanite subfacies or at a somewhat lower subfacies. The monazite belt in the eastern Piedmont seems to be confined to a narrow zone of rocks at the staurolite-kyanite subfacies in a region prevailingly underlain by metamorphic rocks at the albite-epidote-amphibolite facies or a lower facies (Parker and Broadhurst, 1959, p. 4; Overstreet, Over- street, and Bell, 1960; Overstreet and Bell, 1962). The composition of monazite from the eastern belt in the Piedmont of the Carolinas was unknown in 1962. Analyses of monazite from four samples of granite exposed in the Blue Ridge belt in Macon and Jackson Counties, N.C., disclosed 4.3~5.7 percent of ThOZ with an average of 5.0 percent (K. J. Murata, written commun., 1955). Monazite from pegmatite in Madison County was reported (Pratt, 1916, p. 27) to contain 5 percent of ThOZ, and monazite from peg- matite in Mitchell County contains 5.51 percent of Th02 (Bliss, 1944, p. 329). Abundances of thorium oxide on the order of 5 percent or less in monazite from granite and pegmatite resemble the amounts of thorium oxide found elsewhere in the world in mona- zite from granite or pegmatite associated with sedi- mentary rocks metamorphosed at the staurolite-kya— nite subfacies (Overstreet, 1960, p. B56). Apparent ages of minerals in the Blue Ridge belt show that monazite-bearing rocks were formed dur- ing at least two metamorphic episodes, one of which occurred in Precambrian time and the other in Ordo- vician time (Rodgers, 1952, p. 419—423). The age of the main metamorphism in the eastern belt is not known; however, the age of zircon in late monazite- bearing granitic plutons in the eastern belt in South Carolina is Carboniferous (Overstreet and Bell, 1962). These observations and inferences are interpreted by the writer as showing that the monazite belts in Yates, 189 the Carolinas were produced by regional meta- morphism of sedimentary rocks. From west to east the belts seem to have been formed by successively younger orogenic episodes, although the older belts do show some effects from these younger episodes. The monazite in the metasedimentary rocks is a meta- morphic mineral derived from normal components in average shales and sandstones. Sedimentary enrich- ment by concentration of heavy minerals prior to metamorphism is unnecessary to account for the present distribution of the monazite and cannot ac- count for the systematic variations in its composition and abundance The composition and abundance of monazite are influenced by the metamorphic facies so that at the highest facies monazite is more abundant and richer in thorium oxide than monazite in rocks of lower facies. Monazite is more common in syn- kinematic granitic rocks than in the wallrocks, and it is richer in thorium oxide than is monazite from the wallrocks. The granitic rocks, however, underlie only about one—tenth of the monazite-bearing areas; therefore, they are less of a source for monazite in Recent placers than metasedimentary rocks. The gen- eralizations regarding the relation between metamor- phic facies and abundance and composition of monazite provide a basis for predicting on a world—wide scale the location of monazite occurrences and the amount of thorium oxide likely to be found in the monazite. Individual monazite occurrences in North Carolina are discussed in geographic order from west to east. CRYSTALLINE ROCKS AND PLAGERS IN THE BLUE RIDGE movmcn SPRUCE PINE DISTRICT The Spruce Pine mica pegmatite district in parts of Mitchell, Yancey, and Avery Counties has been cited repeatedly as a source for coarse-grained mona- zite since 1880 when W. E. Hidden discovered well- formed crystals which were as much as 11/2 inches wide and nearly an inch long at an unspecified lo- cality in Mitchell County (Hidden, 1880, p. 85; Genth and Kerr, 1881, p. 73; Dana, E. S., 1882, p. 248; Genth, 1891, p. 77—78; Pratt, 1903, p. 180; Sterrett, 1908b, p. 285; Hafer, 1941, p. 306; Stern, 1950, p. 33). At the McKinney mine in Mitchell County scarce pieces of monazite weighing 2—3 pounds were reported to have been found (Ray, 1958, p. 296—297). Mona- zite, however, is actually a very uncommon mineral in the district. The Spruce Pine district is underlain by Pre- cambrian metasedimentary and metavolcanic rocks consisting of interlayered micaceous and hornblendic gneiss and schist, kyanitic gneiss, garnetiferous gneiss 190 and schist, and chloritic rocks (Olson, 1944, p. 16—21). With these are various migmatitic rocks formed by the impregnation of the schists with granitic material. Intrusive into the metamorphic rocks are dunite, alas- kite, and granitic pegmatite genetically related to the alaskite. Relations among the rocks are exceedingly complex. Apparently the sedimentary and volcanic rocks were metamorphosed at least once during Pre- cambrian time and again in middle Paleozoic time. During or at the culmination of the middle Paleozoic episode, the alaskite and associated pegmatite dikes were emplaced (Bryant and Reed, 1960, p. 3; 1962, p. 164—165). The maximum metamorphic facies achieved was the staurolite—kyanite subfacies. Monazite has been observed in the metasedimentary schists and gneisses at only a few places in the dis- trict. It is present as coarse crystals of probable peg- matitic origin in mica schist at the Deake mine in Mitchell County (Hidden, 1880, p. 85; Genth and Kerr, 1881, p. 73; Dana, E. S., 1882, p. 248; Genth, 1891, p. 77), and in garnetiferous kyanite schist at the Celo kyanite mine 4.3 miles east of Burnsville, Yancey County (Brannock, 1943). The kyanite schist is composed of biotite, muscovite, kyanite, feldspar, quartz, and graphite with minor black tourmaline, apatite, sericite, monazite, and chlorite. Monazite occurs in alaskite at localities 1.7 miles northwest and 5.2 miles west of Spruce Pine, Mitchell County, and in either alaskite or migmatite exposed 4.2 miles west of Spruce Pine (Mertie, 1953, p. 18). Only five pegmatite dikes out of the many hundreds of dikes in the district were reported to contain mona- zite. According to W. R. Griflitts (oral commun., 1960), the monazite-bearing dikes are restricted to the southeastern part of the district where alaskite is most common. In the northern and western parts of the district, monazite is generally absent from the pegmatites, but allanite is present. The only known exception to Griflitts’ generalization is the Ray mica mine in the extreme western part of the district about 4 miles north-northeast of Burnsville, Yancey County, where very sparse complex euhedral crystals of mona- zite were said to occur in feldspar (Hidden, 1880, p. 85; Genth and Kerr, 1881, p. 73, 121; Dan-a, E. S., 1882, p. 248; Phillips, 1888; Genth, 1891, p. 78). Hidden lists the specific gravity of the monazite as 5.243. Schists at and near the Ray mine are very kyanitic (Genth and Kerr, 1881, p. 53). The four other monazite-bearing mica pegmatite dikes are eX- posed in the southeastern part of the district at the Deer Park No. 5 mine, the Deake mine, and the Mc- Kinney mine in Mitchell County, and the Number 20 mine in Yancey County. THE GEOLOGIC OCCURRENCE OF MONAZITE The Deer Park No. 5 mine is about 2.5 miles west- northwest of Spruce Pine on a point of land in a sharp bend of the North Toe River (Olson, 1944, pls. 2, 3, 3A, 4). It exposes a large plagioclase and microcline- perthite pegm-atite dike having a core of coarse micro- cline—perthite pegmatite. The dike intrudes a body of alaskite in which there are long folded septa of mica gneiss and schist interlayered with subordinate horn- blende gneiss and migmatite. Resinous yellow mona- zite from this pegmatite has :a specific gravity of 5.18. The monazite was reported to contain 0.02 percent of U308 and has an average of 5.51 percent of Th02 as disclosed by two analyses which showed 5.48 and 5.54 percent of ThOz (Bliss, 1944, p. 327, 329; Rodgers, 1952, p. 421). The Deake mine is about a mile west-northwest of Spruce Pine in an area underlain by migmatite formed from dissemination of alaskite in‘mica schist and mica gneiss (Olson, 1944, pl. 1). Mica schist from the mine has long been reported to contain coarse crystals of monazite (Hidden, 1880, p. 83; Genth and Kerr, 1881, p. 73; Dana, E. S., 1882, p. 248; Genth, 1891, p. 77— 78). Because of their large size these crystals are probably genetically related to the alaskite or peg- matite. The McKinney mine is about 5.8 miles southwest of Spruce Pine in a band of mica gneiss (Olson, 1944, pl. 1). Monazite is one of the less common minerals in the pegmatite at this mine (Ray, 1958, p. 296-297), but it has been found in pieces as weighing as much as 3 pounds. Large pieces of monazite are brick red, but fine-grained monazite is yellow. Threadlike veins of an unidentified black mineral, possibly gadolinite, cut the coarse-grained monazite. Other rare minerals in the pegmatite dike are samarskite, columbite, tor- bernite, sphalerite, uranophane, chalcopyrite, uranin- ite, and beryl. The Number 20 mine is in migmatite and alaskite exposed along Crabtree Creek in Yancey County about a mile north-northwest of the McKinney mine. Mas- sive yellow monazite is associated with thulite and cyrtolite in the pegmatite (Ray, 1958, p. 297—299). Other scarce minerals associated with the monazite are uraninite, gummite, clarkeite, allanite, and calcite. Al- lanite replaces monazite at this locality (Murata and others, 1957, p. 155). The results of an analysis of the rare earth and thorium oxide precipitate from this monazite was published by Murata, Rose, Carron, and Glass (1957, p. 148), and the rare earths and thorium oxide were said to total 66.12 percent of the monazite (H. J. Rose J r., oral commun., 1960). The published results recalculated to sum 66.12 percent Show that monazite from this pegmatite contains 8.18 percent of NORTH CAROLINA Th02, which is an unusually large percentage for mon- azite from the Blue Ridge: [Analystsr Murata and Rose, U. s. Geol. Survey. Recalculated by writer from published analysis] Percent Lazoa _____________________________________ 10. 56 Geo; ______________________________________ 22. 40 P1301; _____________________________________ 2. 78 Nd203 _____________________________________ 12.04 Sm203 _____________________________________ 4. 68 Gdan _____________________________________ 2. 57 Y303 ______________________________________ 2. 91 ThOZ ______________________________________ 8. 18 Total ________________________________ 66. 12 MADISON COUNTY AND HAYWOOD COUNTY Two remarkable occurrences of monazite are known in Madison County. One of these is a monazite-bear- ing pegmatite at Mars Hill in the eastern part of the county, the other is in the Snowbird Group in the Ocoee Series of Precambrian age in the northwestern part of the county. A single doubtful occurrence of monazite in gneiss exposed in Haywood County has been reported. As early as 1891, large cleavable masses of monazite, some as much as 4 inches across, had been found in the vicinity of Mars Hill, Madison County, but the specific locality was not described (Genth, 1891, p. 74). Several subsequent reports continued to refer to the large crystals and indicated that they occurred in a pegmatite dike in the Mars Hill area, but again exact localities were not cited; however, in 1913 J. H. Pratt noted that one of the masses of monazite weighed 60 pounds (Pratt, 1903, p. 181-182; 1913). In 1916 Pratt gave the first discussion of the location and geology of the Mars Hill deposit (Pratt, 1916, p. 47—48). Further brief reference was made to the locality in 1918 by Pratt (1918, p. 455), and in that same year the deposit was visited by Schaller (1933), who long afterwards published a description of the 60-pound crystal of mon- azite found there. Passing mention of the deposit was accorded by Drane and Stuckey (1925, p. 19), and Bry- son (1927, p. 16). Interest in the deposit revived in the late 1930’s when samples of the monazite were analyzed in investigations to determine the geologic age of the mineral (Marble, 1936; Lane, 1936, p. 64; 1937, p. 58; Rodgers, 1952, p. 421). Mineral collectors were ap- prised of the locality in 1942 (Brannock, 1942, p. 85). The following description of monazite at Mars Hill is drawn mainly from Pratt (1916) and Schaller (1933), with additional geological data from Hash and Van Horn (1951, p. 18). The Mars Hill monazite deposit is about 3 miles southwest of Mars Hill, Madison County, on the farm 191 formerly owned by the late Rev. N. P. M. Corn. The deposit proper is a pegmatite dike and associated peg- matite-impregnated zone, 15 feet wide or less, in what may be Cranberry Granite Gneiss of Precambrian age. Possibly part of the pegmatized zone is in a septum of layered gneiss and schist, but owing to deep weathering the rocks have not been identified with certainty. At least some of the rocks in the Mars Hill area are mas- sive to schistose sillimanite-garnet-biotite gneiss (Hash and Van Horn, 1951, p. 18), but sillimanitic rocks have not been reported from the Corn farm. The pegma- tized zone and pegmatite dike trend N. 30° E. about parallel to contacts between Cranberry Granite Gneiss and septa of layered gneiss and schist. Neither the pegmatized zone nor the dike crop out clearly, but sev- eral pits and a shaft along the probable trend disclose the zone for at least 100 feet on strike, and cleavage fragments of monazite float are scattered abundantly along the ground for several hundred feet south of the pits. Possibly several lens-shaped masses of pegmatite instead of a single dike occupy the pegmatized zone. The exposed part of the pegmatite dike seems to be zoned: along its east side is dark-green mica as much as 1 foot thick, adjoining the mica on the west is massive quartz 1—2 feet thick, and adjacent to the quartz is the main body of the dike, which is composed chiefly of feldspar and is of unreported Width. Monazite occurs in the feldspathic and micaceous parts of the dike and in the pegmatized zone in the wallrocks (Pratt, 1916, p. 47; Schaller, 1933, p. 439; Mertie, 1953, p. 18). The coarse-grained monazite occupies a layer 1—4 inches wide, but locally much wider, in the mica zone in the dike. Doubtless there are several such monazite—rich layers instead of a single continuous one. Presumably the giant crystal of monazite described by Schaller came from one of these layers in the dike; certainly most of the coarse-grained float and the lump monazite mined from the deposit came from the layer. Monazite from the feldspathic part of the dike and from the pegmatized zone in the wallrocks is relatively fine grained. According to Schaller (1933, p. 439), the layer in the mica zone contains about 37 percent of monazite: Percent Monazite layer in mica zone _________________________ 36. 90 Mica zone in pegmatite ______________________________ 1. 06 Feldspar zone in pegmatite ___________________________ . 33 Pegmatized zone in country rock _____________________ . 05 Well-terminated crystals of monazite weighing 61/;— 12 pounds were found at the deposit soon after it was discovered, and several large cleavable masses, rough crystals, and irregular fragments of monazite have been found. The largest crystal of monazite taken 192 from the deposit weighed almost exactly 60 pounds when it was collected, but when it was examined by Schaller in 1918 it weighed 58% pounds. In its pres- ent form the crystal measures 61/2 inches along the a axis, 9% inches along the b axis, and 11 inches along the c axis. For many years it was in the Burnham S. Colburn mineral collection at Biltmore Forest, NC, but it was acquired by the geological museum of the University of South Carolina and at this writing (1962) is on display at Columbia, 8.0. So far as is known, this is the largest monazite crystal ever dis- covered. Analyses of monazite from the Corn farm near Mars Hill have shown that the monazite contains from 5.06 to 7.0 percent of ThOz . Pratt (1916, p. 48) reported 5.06 percent of T1102 . Schaller (1933) determined 6.06 percent of Th02 and observed that another analyst had found 7 percent of Th02 . Two analyses by Mar- ble (1936) disclosed 6.30 and 6.38 percent of ThOZ with 0.022 and 0.019 percent of U308. Microchemical analyses by Edith Kroupa in 1936 (Lane, 1937, p. 58) showed 6.31 and 6.55 percent of Th0,: Percent Percent RE203 _____________ 63. 29 MgO ______________ 0. 15 Th02 ______________ 1 6. 55 PbO _______________ . 179 U30a___; ___________ 2 . 036 34110 ______________ . 16 P205- _ _ J. __________ 23. 44 H20 — _____________ . 28 SiOz _______________ 2. 03 H20+ _____________ 1. 22 A1203 ______________ 1. 64 Insoluble residue____ . 40 F8203 ______________ 1.74 0210 _______________ . 80 Total ________ 3 101. 91 1 In a second determination found to be 6.31 percent. 1 In a second determination found to be 0.042 percent. I Total reported as 101.80 percent. The monazite deposit on the Corn farm near Mars Hill was said to have been opened in 1902 by Paul S. Corn (Schaller, 1933, p. 437) and to have been worked intermittently for 2 years thereafter. Sporadic devel- opment was attempted as late as 1918. Several hun- dred pounds of monazite have been carried away from the deposit by visitors, but there is no record of com- mercial shipments. Relict detrital monazite was observed by Oriel (1950, p. 29) in thin sections of mylonitized feldspathic sand- stone, arkose, and micaceous sandstone in the Precam- brian Snowbird Group of the Ocoee Series in the vicin- ity of Hot Springs, Madison County. Mylonites at one or more of the following localities contain monazite, but which ones specifically are monazite-bearing was not stated by Oriel: head of the east fork of the Coon- patch Branch; locality 2,800 feet north-northeast of Anderson Cemetery on Spring Creek Mountain; local- ity 3,800 feet due south of Mill Ridge Church; and lo- cality in a roadcut near 'bench mark P58 to the south- west of Tanyard Gap on US. Route 25—70. THE GEOLOGIC OCCURRENCE OF MONAZITE The presence of detrital monazite in the Precam- brian Snowbird Group of the Ocoee Series demon- strates that the source rocks of the detrital monazite are part of the older Precambrian complex of the Blue Ridge. Therefore, some very old rocks are monazite- bearing in the Blue Ridge monazite belt. One sample out of four samples of Precambrian gneiss and granite underlying the Ocoee Series in Hay- wood County was reported by Carroll, Neuman, and Jafl'e (1957, p. 186) to contain possible monazite ac— companied by zircon and epidote. The possible mona- zite is in gneiss exposed near Fines Creek. ZERCONIA DISTRICT Monazite was reported in 1888 by Hidden (1888b, p. 381—382) as one of a variety of heavy minerals occur- ring in decomposed granitic rock exposed on the Davis land between Zirconia Station and Poinsett Spring about 4 miles from Green River Post Office, Henderson County. Zircon was especially plentiful, and xenotime and magnetite were present. The occurrence was again mentioned by Genth (1891, p. 49, 86) who reported that zircon had been mined in the Zirconia district as early as 1869 and that Hidden shipped 25 short tons of zircon from one property in the area in 1888. There- after intermittent mining of zircon continued through about 1916 (Olson, 1952, p. 18), but monazite was not produced. The monazite-bearing rocks of the Zirconia pegma» tite district were described by Olson (1952, p. 17—22) as syenite and quartz syenite pegmatite dikes which occur in and near a large septum of schist and gneiss in foliated granite. The septum is 0.5-1 mile wide and at least 3 miles long. It consists of biotitic and silliman- itic schists and banded feldspathic gneisses the folia- tion of which is athwart the trend of the septum. The dikes consist mainly of microcline with small quantities of albite and very sparse quartz. In addition to these minerals and the previously mentioned accessories, the dikes were said to contain anatase, sphene, titaniferous garnet, polycrase, allanite, auerlite, epidote, stilbite, apatite, beryl, muscovite, calcite, kaolin, and decom- posed hydrated mica, which may be vermiculite. Wall zones of large dikes are as much as 15—20 feet thick and are especially rich in vermiculite. The vermiculite does not seem to be derived from alteration of the enclosing rocks, which are light-colored granitic gneisses. The unusual concentration of zircon in the pegmatite of the Zirconia district is greater than the concentra- tions of zircon associated with other crystalline rocks in the State except syenite (Mertie, 1958, p. 19). Mon- azite, however, is absent from syenite in North Caro- lina and is only known in syenite pegmatite in the Zir- NORTH CAROLINA conia district in the Blue Ridge and in syenite pegma- tite at a few localities in the Piedmont. The Zirconia district is considerably east of the Blue Ridge monazite belt as defined by occurrences of mona- zite in Mitchell, Yancey, Madison, and Haywood Coun- ties. It is also somewhat west of the northwest edge of the monazite belt in the western Piedmont of North and South Carolina. The occurrence of monazite in syenite pegmatite is also unlike the usual occurrences in schists, gneisses, granitic rocks, and granitic pegmatites in the monazite belts in the Blue Ridge and western Piedmont. In geologic age the syenite pegmatite of the Zirconia district is considerably younger than the mon- azite-bearing rocks of these two belts. The syenite pegmatite is probably Permian in age, whereas the monazite-bearing granite pegmatites of the western Piedmont and Blue Ridge are probably no younger than Ordovician, and some monazite-bearing gneiss and schist in the Blue Ridge is of Precambrian age (Overstreet, Bell and others, 1961; Overstreet and Bell, 1962, map). The apparent age of the syenite pegma- tite in the Zirconia district is the same as the apparent age of monazite-bearing granites in the South Carolina segment of the easternmost monazite belt in the Pied- mont. It is therefore probable that monazite in the Zirconia district is unrelated to the geologic events re- sponsible for the formation of monazite occurrences in the Blue Ridge and western Piedmont belts. The Zir- conia occurrences are seemingly related to igneous ac- tivity that prevailed at the time of formation of the easternmost monazite belt in the Piedmont. MACON, JACKSON, AND CLAY COUNTIES Highly micaceous saprolite exposed in the beds of Masons Branch, Caler Fork of Cowee Creek, and other tributaries to the Little Tennessee River 5-8 miles north of Franklin in Macon County was said to con~ tain accessory monazite (Judd and Hidden, 1899, p. 142). Concentrates panned from the saprolite con- tained sillimanite, staurolite, ilmenite, rutile, monazite, spinel, rhodolite garnet, corundum, gold, and Sperry- lite. The micaceous rocks were described as being in- terlayered with various mafic rocks including garnet amphibolite (called hornblende eclogite), amphibolite, and hornblende gneiss. Cutting these are mafic dikes and pegmatite. Alluvium in Masons Branch had ear- lier been described as monazite-bearing by Hidden and Pratt (1898a, p. 294; 1898b, p. 466), and the stream gravel was the discovery locality for the variety of garnet they named rhodolite. Other detrital heavy minerals in alluvium from Masons Branch were re- ported to be corundum, pleonaste, gahnite, bronzite, cordierite, kyanite, sillimanite, hornblende, staurolite, 238—813——67 14 193 rutile, ilmenite, chromite, zircon, gold, and sperrylite. Monazite was also found in the alluvium of Caler Fork Where sperrylite was first identified in North Carolina (Hidden, 1898, p. 381). From these old reports it seems that monazite in this area occurs in some form of mica schist, possibly kyanitic, sillimanitic, or corundum—bearing. In de- scriptions of the geology of rhodolite deposits on Mas- ons Mountain, situated between Masons Branch and Caler Fork, E. P. Henderson (1931, p. 563—565) and Heinrich (1950b, p. 7 64—770) did not report monazite as a constituent of the complex suite of mafic rocks in which the rhodolite is found, nor did Heinrich report it in the mica pegmatites and kyanite- and staurolite-bear- ing pegmatites associated with the rhodolite deposits. The paragenetic sequence worked out by Heinrich for the rhodolite-bearing rocks indicates that rhodolite- hypersthene gneisses were formed in an early meta- morphic stage. Prior descriptions under the term “hornblende eclogite” of what is probably the same rock as the rhodolite-hypersthene gneiss and reference to the abundance of sillimanite indicate that high lev- els of metamorphism may have been reached in the Masons Mountain area. The regional details are, how- ever, very imperfectly known, as are the sources and origin of the monazite. Monazite from the Masons Mountain area forms eu- hedral crystals in only a few places (Hidden and Pratt, 1898b, p. 466). It occurs as minute grains that are commonly perfectly transparent, very brilliant, and yellow (Judd and Hidden, 1899, p. 147). Megascopic brown and green varieties of monazite are sparse, and a few green rough crystals as much as 0.25 inch across have been found. The minute yellow variety of monazite was stated to contain only 0.03 percent of Th02 , but the other com- ponents were not identified and the source of the analy- sis was not given (Hidden, 1898, p. 381; Judd and Hidden, 1899, p. 147). A question may exist if the m a t e rial analyzed was actually monazite or was xenotime. In the original reference (Hidden, 1898, p. 381) the statement on composition was given as a footnote and in another reference Hidden and Pratt (1898b, p. 466) likened the possible abundance of thorium and uranium in the green monazite at the Masons Mountain area to that in green xenotime at Brindletown, Burke County, N.C., samples of which were analyzed by L. G. Eakins of the U.S. Geological Survey and found to contain only a trace of thorium oxide (Hidden, 1893, p. 256—257). The small amount of thorium oxide attributed to the Masons Mountain monazite is exceptional for monazite from what may possibly be an unusually plutonic environment. If the 194 monazite formed in mica schists under the same meta- morphic conditions in which rhodolite-hypersthene gneisses crystallized, then it might be expected to con- tain hundreds of times more thorium oxide than is reported. Some of the so-called green monazite might even be cheralite. The position of monazite in the par- agenetic sequence at this locality needs to be clarified, and the composition of the monazite needs to be deter- mined. Prior to analysis the material should be exam- ined under unfiltered ultraviolet light by the method of Murata and Bastron (1956) to insure that xenotime is excluded. Whiteside Granite exposed near Highlands in Macon County and at a point west of Cashiers in Jackson County was found by W. R. Griflitts (written commun., 1955) to be monazite bearing. Analyses by K. J. Mur— ata and H. J. Rose, Jr., of the U.S. Geological Survey of four samples disclosed that it contains only mod- erate amounts of thorium but that it has the remark- ably high average Ce/ (Nd + Y) atomic ratio of 2.99 (table 60). According to Murata and associates (1953, p. 296—299; 1957, p. 150, 153, figs. 2, 5), an atomic ratio as great as 2.99 indicates very highly fractionated monazite dominated by basic rare earths, principally lanthanum and cerium with praseodymium. In a mag- matic rock such monazite presumably would be formed only after the long-continued fractional precipita- tion of less basic rare earths had left the magna rela- tively enriched in lanthanum and cerium (Murata and others, 1957, p. 150). Uncertainty attaches to the origin of the Whiteside Granite, and it cannot posi- tively be regarded as magmatic (Overstreet and Bell, 1962); hence, the monazite may not have been pro- duced by fractional crystallization in a magma. An TABLE 60.—Thorium, uranium, and rare-earth composition of monazite from Whiteside Granite exposed in Macon and Jackson Counties, N.C. [Quantitative spectrochemlcal analyses by K. J. Murata and H. 1'. Rose, J r.; chemical analyses for uranium by Carmen Johnson; samples collected by W. R. Griflitts, U.S. Geol. Survey, 1955] Th0: U105 Aggggc Lab. No. Source of monazite Location of samples C 8 Weight percent ~ (Nd+Y) 144567 ......... Muscovitic 5 miles west of 4. 3 0. 13 2. 77 Whiteside Highlands, Granite. Macon County, along U.S. Route 64. 68 ......... Biotitic White— _____ do ............. 5.1 . 13 2. 97 side Granite. 69 .............. do _____________ Along U.S. Route 5. 2 . 35 3. 40 64 at north edge of Highlands. 70 .............. do _____________ 3.75 miles west of 5. 7 . 24 2. 85 Cashiers, J ack- son County, along U.S. Route 64. Average. _.._ .-. 5. 0 . 24 2. 99 THE GEOLOGIC OCCURRENCE OF MONAZITE interesting possible explanation for the dominance of basic rare earths in monazite from the Whiteside Gran- ite is that the monazite is of metamorphic origin, and in metamorphic differentiation the most soluble rare earths tend to migrate into the mobilized part of the metamorphosed rocks. Inasmuch as the most soluble rare earths are lanthanum, cerium, and praseodymium, it is these elements with which the monazite is en- riched. Repeated episodes of metamorphism over a long period of time might be effective in producing monazite that is unusually rich in basic rare earths. Age determinations on minerals in the Whiteside Granite strongly suggest that it is a polymetamorphic rock (J affe and others, 1959, p. 115-116; Overstreet and Bell, 1962). The Horse Cove region of Jackson County near the border with Macon County and about 2 miles east of Highlands was the source in the early 1900’s of several monazite-bearing concentrates panned from stream de- posits (Pratt and Sterrett, 1908a, p. 314). Several fairly rich monazite placers were stated to have been found in the early 1900’s by George L. Eng- lish in Clay County, but the valleys are small and the occurrences were regarded as of little economic value (Pratt and Sterrett, 1908a, p. 315). The general pos~ sibility of placer deposits in the Blue Ridge, however, has not been carefully evaluated. Particularly, the possibility of fossil placers associated with old river terrace levels (Hunter, CE, 1940, p. 101) seems to have been neglected. CRYSTALLINE ROCKS IN THE WESTERN MONAZITE BELT IN THE PIEDMONT PROVINCE The greatest number of reported occurrences of mon- azite in North Carolina are in crystalline rocks of the Piedmont in the area defined as the western monazite belt by Mertie (1953, pl. 1; Olson and Adams, 1962, map). This belt is also the region where stream plac- ers were formerly mined for monazite. Because of the economic interest that has attached thereto, the belt in the western Piedmont has received more attention than other places where monazite has been found in the State. Monazite-bearing crystalline rocks of the belt extend southwest across North Carolina from Stokes and Surry Counties on the northeast to the border with South Carolina along the south edge of Polk, Ruther- ford, and Cleveland Counties. Not all rocks in the belt are monazite bearing, but very few monazite occur- rences are known in the Piedmont outside this belt and the eastern belt described farther along. Perhaps as much as 10—15 percent of the area of the belt is underlain by massive to gneissic granitic rocks mainly of granodioritic to quartz monzonitic composition. Masses of the granitic rock tend to con- NORTH CAROLINA form to the structure of the enclosing paragneiss and paraschist, but locally they are sharply crosscutting, and generally they contain inclusions of the wallrocks. At most places the inclusions have reaction rims or other alteration. Mutual relations of the rocks have been interpreted to show that the masses of granite were formed during a minimum of two orogenic epi- sodes. The earlier and more profound episode prob- ably took place in Ordovician time. The younger episode is of late Paleozoic age and probably marks the close of Appalachian mountain building in this region (Overstreet and Bell, 1962). Schist and gneiss formed from sedimentary and py- roclastic rocks are the principal components of the western monazite belt in North Carolina. The belt oc- cupies an exceptionally well-defined zone of progres- sive regional metamorphism (Overstreet and Griffitts, 1955, p. 555—566; Overstreet, Cuppels, and White, 1956). The highest metamorphic facies reached is the sillimanite-almandine subfacies. Rocks of this facies form the core of the belt southwestward from the Yad- kin River in the vicinity of the border between Wilkes and Iredell Counties (Hunter and White, 1946, pl. 1) to the South Carolina State line. The sillimanitic core of the belt reaches its greatest width, about 25 miles, in Cleveland and Rutherford Counties; from there it ex- tends southwestward nearly across South Carolina. Within this core are most of the monazite occurrences known in the belt and the largest part of the monazite containing 4.5 percent of ThOz or more. The remain- der of the occurrences, and generally ones yielding monazite with 4.5 percent of Th02 or less, are along the southeast and northwest flanks of the belt and in the full width of the belt northeastward from the vi- cinity of the Yadkin River near the border between Wilkes and Iredell Counties. In these flanking areas the metasedimentary rocks are at the staurolite-kyanite subfacies or lower metamorphic facies. The zone of closure of rocks of lower facies around the sillimanitic core of the belt in the vicinity of the Yadkin River, ef- fectively defines the limit of known monazite placers at the time mining ceased (Pratt, 1916, pl. 1). Northeast of the northeastern end of the sillimanitic core of the belt there are few occurrences of monazite in the lower rank rocks, and these occurrences do not give rise to placers that are large or high in tenor. STOKES COUNTY AND SURRY WUNTY The rocks of the monazite belt in the western Pied— mont of North Carolina in Stokes County and Surry County are characteristically of medium and low meta- morphic facies. 195 The Ridgeway—Sandy Ridge pegmatite district in North Carolina and Virginia was said by Griflitts, Jtahns, and Lemhke (1953, p. 143—146) to contain gran- itic rocks that are locally monazite bearing, but the muscovite pegmatites are barren of monazite. The southern part of the district is named after Sandy Ridge in Stokes County. The area is mainly underlain by garnetiferous muscovite schist consisting of musco- vite, quartz, sodic plagioclase, biotite, and garnet, with accessory epidote, magnetite, ilmenite, sphene, tourma- line, zircon, and rutile. Biotite gneiss forms layers as much as 500 feet in thickness in the muscovite schist; it is composed of oligoclase, orthoclase, quartz, biotite, muscovite, and epidote with accessory apatite, garnet, zircon, sphene, magnetite, and pyrite. Scarce thin lay- ers of hornblende gneiss are present, and masses of hornblende gabbro intrude the metamorphic rocks in the northeastern part of the district. Small concord- ant bodies of light-gray foliated quartz monzonite and quartz diorite occur throughout the district. Micro- cline, oligoclase, quartz, biotite, muscovite, garnet, apa- tite, and epidote are its principal components. Acces- sory minerals are zircon, magnetite, sphene, sericite, and, very locally, monazite. Monazite is not known to occur in the other rocks of the district, and specific monazite localities in the Sandy Ridge area have not been reported. The granitic rock at five localities in and about Mount Airy, Surry County, and granite gneiss exposed 4.7 miles by road south of Dobson, Surry County, were shown by Mertie (1953, p. 18—19) to contain accessory monazite. In a detailed description of the granitic rock at Mount Airy, Dietrich (1961, p. 7-8) classed it as a postkinematic leucogranodiorite of mesozone em- placement. Dietrich (1961, p. 10) observed that the leucogranodiorite and a late magmatic dike in it con- tain grains of accessory monazite which are generally surrounded by thin coronalike coatings of epidote. Where the monazite is not rimmed with epidote, it occurs between plates of biotite, but even some of these monazite grains are partly coated by epidote which lies between the monazite and the biotite. Monazite grains inside of epidote rims are smaller than un- rimmed particles of monazite. Some monazite grains are in contact with apatite on one side and epidote on the other. Sphene encloses magnetite, apatite, and monazite and is enclosed by epidote (Dietrich, 1961, p. 12). According to Dietrich (1961, p. 33—35), the mon- azite seems to have formed very early in the sequence of crystallization of the minerals in the leucogranodi- orite. It was preceded only by magnetite and by the earliest-formed apatite. Some of the epidote is inter- preted to be probably pyrogenic, and to this variety is 196 assigned tentatively the epidote-forming rims on the monazite (Dietrich, 1961, p. 35). Reconnaissance observations made by the present writer and his associates (Overstreet and Griflitts, 1955, p. 563—564) suggest that the body of leucogranodiorite at Mount Airy in its broadest relations is transgressive, postkinematic, and emplaced under less deep-seated conditions than monazite-bearing granitic rocks ex- posed farther southwest in the sillimanitic core of the monazite belt. The relations between monazite and epidote in the leucogranodiorite, first described in R. V. Dietrich’s detailed study, are here interpreted as showing possible lack of stability of magmatic mona- zite under conditions of mesozonal emplacement. It is here suggested that the monazite formed early in the magma chamber, and as the body of magma moved toward its zone of emplacement and final crystalliza- tion, the pressure-temperature conditions were lowered and monazite became unstable. Incomplete reaction between monazite and the magma are inferred to have led to partial replacement of monazite by epidote, apa- tite, and sphene. Shallower examples of the leuc0~ granodiorite might be expected to show more com- plete reaction culminating in elimination of monazite as a mineral phase, but details of the areal geology are as yet not well enough known to test this inference. WILKES, ALEXANDER, CATAWBA, CALDWELL, BURKE AND MCDOWELL COUNTES In 1950 banded granitic gneiss exposed about 8 miles east of VVilkesboro, Wilkes County, was found by Mer- tie (1953, p. 18) to contain monazite, but detrital mon- azite had been discovered in the county at least as early as 1906 by D. B. Sterrett (Pratt, 1907b, p. 109). The monazite-bearing gneiss is within the sillimanite zone defined by Hunter and White (1946, p. 1) about 10 or 12 miles southwest of the northeast end of the silliman- itic core of the monazite belt. Monazite crystals were found by W. E. Hidden about 1880 in a muscovite-rich vein in garnetiferous mica schist at Milhollands Mill in Alexander County (Genth and Kerr, 1881, p. 73; Dana, 1882, p. 247; Hid- den, 1888b, p. 381; Pratt, 1903, p. 180). Accompany- ing the monazite and muscovite were geniculated crys- tals of rutile, xenotime, quartz crystals, and pseudo— morphs of limonite after siderite. Most of the mona- zite formed very minute grains, but some particles were about 0.05 inch across, and a few splendent transpar- ent crystals were 0.25 inch long. These large crystals, or ones from the Emerald and Hiddenite mine discussed in the following paragraphs, may have been the mate- rial displayed by Hidden (1885, p. 183) at the New Orleans World’s Industrial and Cotton Centennial Ex- THE GEOLOGIC OCCURRENCE OF MONAZITE position of 1884—85. The original site of Milhollands Mill was described by Mertie (1953, p. 8) as on Third Creek about 2.6 miles S. 30° E. from Hiddenite, Alex- ander County. The Emerald and Hiddenite mine is on the Warren farm in Alexander County south of the road between Stony Point and Hiddenite and about 1.5 miles south of the latter settlement. Stony Point was W. E. Hid- den’s field headquarters late in 1880 when he was searching for monazite and other minerals needed for incandescent lamps. Among the monazite-bearing peg- matite dikes he examined in this area were the minera~ logically unusual ones on the Warren farm, which he found to contain a scarce green variety of spodumene subsequently named hiddenite by J. L. Smith. In the late 1800’s and early 1900’s the dikes were exploited for hiddenite for gem use by operations at the Emerald and Hiddenite mine. Since then the locality has been noted as a source for hiddenite, but comments also have been published about splendid crystals of monazite, quartz, and rutile (Dana, 1884, p. 542; Genth, 1891, p. 86; Pratt, 1933, p. 153). The most complete description of the pegmatite dikes at the Emerald and Hiddenite mine was given by Pal- ache, Davidson, and Goranson (1930). According to this report the rocks in the vicinity of the mine are andesine—quartz-biotite-garnet gneiss formed by pro- found polymetamorphism of argillaceous sandstone. Rounded zircon grains are present in the gneiss. Aver- age proportions of the main components are 50 percent of quartz, 30 percent of biotite, 15 percent of andesine, and 5 percent of garnet, zircon, and apatite. Prior to the last folding of the gneiss, numerous thin lit-par-lit seams of quartz-feldspar pegmatite were formed. The lit-par-lit pegmatite contains quartz, andesine, ortho- clase, microline, bronzite, tourmaline, apatite, and pyrite. In many places the feldspar grains in these veinlets were granulated and drawn out into augen by late folding. Two periods of intrusion of hiddenite- bearing pegmatite followed the formation of the lit- par-lit veins and during the last monazite formed. Monazite is only found in cavities in the pegmatites. The early-formed hiddenite pegmatites consist of quartz, andesine, microcline, hiddenite, tourmaline, garnet, dumortierite, sillimanite, zircon, biotite, seri- cite, rutile, apatite, pyrite, and calcite. The cavities range in size from minute druses to openings several feet in diameter (Palache and others, 1930, p. 286, 301). Some cavities occupy shear planes in the gneiss. They cut across the gneissic layering and are sharply defined. Other cavities are not sharp- ly defined, are surrounded by altered gneiss, and may have formed from solution of parts of earlier formed NORTH CAROLINA pegmatite. These cavities are also lined with free- standing growths of a variety of minerals. Within both types of cavities the paragenetic sequence seems to be quartz, hiddenite and beryl, muscovite, albite, siderite and flat rhomb calcite, quartz, monazite and rutile, andularia, pyrite, and calcite followed by cor- rosion of practically all the minerals and some oxida- tion of pyrite to limonite. Minerals whose position in the sequence were not described but which were said to occur in the cavities are amethyst, holmquistite, tour- maline, garnet, nontronite, apatite, arsenopyrite, anker- ite, and aragonite. Monazite occurs as tiny clear honey-yellow crystals embedded in albite or calcite or attached to walls of the cavities. Its crystals are mod- erately complex and nine forms were identified on them (Palache and others, 1930, p. 298). Composition of the monazite has not been reported. A sample of granite from the Emerald and Hidden- ite mine and a sample of material from the dump, pos- sibly dominantly gneiss, were found by Mertie (1953, p. 17—18) to contain accessory monazite. Gneiss and schist in the general area of these pegmatite deposits were said to contain minor accessory monazite (J ahns and others, 1952, p. 31; Griflitts and Olson, 1953a, p. 205, 207). A locality 3 miles east of Hiddenite, also reported as 3 miles east of the Emerald and Hiddenite mine, was the source of a brown crystal of monazite inter- grown with vein quartz (Bath, 1886, p. 149—150). Very pure transparent crystals of monazite, specific gravity 5.203, from this locality were analyzed and found to have the following composition: [Analystsz Penfield and Sperry (1888, p. 322)] Percent 0e203 ____________________________________ 37. 26 (La, Di)203 _______________________________ 31. 60 Th0; ___________________________________ _ 1. 48 P205 _____________________________________ 29. 32 SiOz ______________________________________ . 32 Loss on ignition ___________________________ . 17 Total ___________________________________ 100. 15 The source of the analyzed monazite was not given, but the appearance of the crystals closely resembles descriptions of monazite from veins and vugs in the Hiddenite-Stony Point area. In this connection it should be noted that detrital monazite from Third Creek at Milhollands Mill, Alexander County, was observed by Mertie (1953, p. 12) to contain 5.19 percent of Th02. The monazite in Third Creek most probably is derived mainly from gneiss, schist, and granite, and the well-known occurrence in veins at Milhollands Mill probably contributes scant monazite to the stream. It seems likely that monazite in veins or vugs in this area contains less thorium oxide than 197 monazite from the wallrocks, but proof of a difference still has to be made. A crystal of light—brown transparent monazite in- cluded in a crystal of clear quartz from an unspecified locality in Alexander County was described by Neal Yedlin (1958, p. 419). The quartz shows a distinct phantom on which the inclusion of monazite seems to rest. The monazite and quartz resemble the inter- growth described by Gerhard vom Bath (1886) from the locality 3 miles east of Hiddenite, and they are doubtless from a vug or vein. As early as 1895 monazite was known in streams along the west edge of Catawba County, where it was derived from gneiss, augen gneiss, and schist, but spe- cific locations of monazite-bearing rocks were not given (Nitze, 1895c; Mezger, 1895, p. 822). Monazite was also reported as an accessory mineral in granite and gneiss in pegmatite district northeast of Hickory, Catawba County, but individual occurrences were not cited (J ahns and others, 1952, p. 31, 37; Griiiitts and Olson, 1953a, p. 218). Accessory monazite has been found in granite and gneiss in the southeastern part of Caldwell County (J ahns and others, 1952, p. 31; Griffitts and Olson, 1953a, p. 218). Burke County at the beginning of the twentieth cen- tury was one of the most productive of the monazite- producing counties, but very little information has been published about bedrock sources of the monazite although there is an extensive literature on the placers. Probably the earliest reference to monazite in the crys- talline rocks in Burke County is Mezger’s (1895, p. 823) observation that lenticular masses of fine-grained granite in the South Mountains near the border with Cleveland County contain 0.2—1.0 percent of monazite. No further descriptions of bedrock sources of monazite were given until 1953 when Mertie (1953, p. 17—18) listed five exposures of monazite-bearing granite and granite gneiss in the vicinity of Jacob Fork River, Pleasant Grove, and the Ramsey area in eastern Burke County. Quartz monzonite and pegmatite that crop out locally in the Piedmont to the southeast of Shortofi' Mountain and north of the Catawba River in the part of Burke County northwest of Morganton commonly contain accessory monazite (Bryant and Reed, 1960, p. 5). The quartz monzonite in this area may be equiv- alent to the Toluca Quartz Monzonite discussed under Cleveland County. Monazite from the crystalline rocks in Burke County has not been analyzed, but several analyses of detrital monazite from the county disclose from 2.48 to 6.68 percent of ThOz . These analyses are listed in the sec- tion on placers, where it is shown that the low-thorium 198 oxide monazite tends to come from streams which flow on medium-grade metamorphic rocks, northwest of the northwest boundary of the sillimanite-almandine sub- facies. The thorium oxide-rich monazite commonly comes from streams underlain by rocks of the silliman- ite-almandine subfacies. Granite gneiss exposed near the McDowell County line east of Nebo contains accessory monazite (Mertie, 1953, p. 17) . Many other occurrences and several anal- yses of monazite have been reported from McDowell County, but they are placer deposits and are discussed farther along. RUTHERFORD COUNTY AND CLEVELAND COUNTY Rutherford County was one of the main sites of the placer monazite industry in North Carolina during the late 1800’s and early 1900’s, particularly the region around Ellenboro in the east-central part of the county (Pratt, 19040, p. 35). Accounts of monazite in crystal- line rocks of the county, however, were lacking until Mertie (1953, p. 17—18) published a record of his sam- pling during 1945 and 1948. He reported monazite in gneiss between Ellenboro and Bostic, in granitized schist at two localities near Spindale in the central part of the county, in granite from the Gilkey area in north-central Rutherford County, and in granite at a quarry 1.5 miles west of Hollis near the east border of the county. Concentrates from 208 samples of saprolite of crys- talline rocks and 88 samples of residual soil in eastern Rutherford County were examined for monazite by R. G. Yates between 1948 and 1951. The samples of sap- rolite comprised 139 specimens of schist and gneiss, 44 samples of pegmatite, and 25 samples of Toluca Quartz Monzonite. Results of this study were coupled with results from similar work in Cleveland County; there- fore, it is not possible to separate them according to TEE GEOLOGIC OCCURRENCE OF MONAZITE county. The distribution of monazite was shown on a map of the Shelby topographic quadrangle (Over- street, Yates, and Griifitts, 1963a, pl. 1) and is dis- cussed in the following paragraphs on Cleveland County. It was found that monazite occurs in half or more of the samples of each kind of rock; 94 percent of the samples of pegmatite and 98 percent of the samples of Toluca Quartz Monzonite are monazite bearing. Sillimanite schist contains about twice as much mona- zite as biotite schist. Residual soil formed on these rocks has a slightly greater incidence and a generally greater amount of monazite than the rocks themselves. Quantitative spectrochemical analyses for thorium (Dutra and Murata, 1954; Rose and others, 1954) and determinations of the 06/ (Nd + Y) ratios in 13 sam- ples of monazite from rocks in eastern Rutherford County were made in 1955 by K. J. Murata and H.J. Rose, Jr. (written commun., 1955) of the U.S. Geo- logical Survey. Carmen Johnson and Blanche Ingram of the Survey analyzed four of the specimens of mona- zite for uranium. Results of these analyses showed that monazite from eastern Rutherford County con- tains from 3.7 to 8.8 percent of Th02 and from 0.22 to 1.48 percent of U308 (table 61) . The average amount of thorium oxide in eight samples of monazite from biotite schist and biotite gneiss is 4.5 percent; the aver- age of three samples of monazite from pegmatite is 7.4 percent, and the average of two specimens of monazite from Toluca Quartz Monzonite is 6.5 percent. Except for samples from pegmatite these average abundances are on the low side of the amounts of thorium oxide usu- ally associated with monazite from upper amphibolite facies metasedimentary rocks and associated synkine- matic granitic rocks (Overstreet, 1960, p. B56). The source area of the monazite in eastern Rutherford County is well within the sillimanitic core of the mona- zite belt. TABLE 61.—Thorium, uranium, and rare-earth composition of monazite from crystalline rocks in eastern Rutherford County, N.C. [Quantitative speetrochemical analyses by K. J. Murata and H. J. Rose, J r.; chemical analyses for uranium by Carmen Johnson and Blanche Ingram, U.S. Geo]. Survey 1955. Symbol used: __, not determined] Th0: UaOa Lab. N 0. Source of monazite Location Atomic ratio Ce/(Nd+ Y) Weight percent 138559 _______ Biotite gneiss _______________ 1 mile west-northwest of Duncans Creek Church ______ 4. 6 __ 3, 50 60 ____________ do _____________________ South flank of Piney Mountain ______________________ 4. 4 0. 33 2, 47 54—539SW____ Toluca Quartz Monzonite- _ __ South flank of Tom Price Mountain _________________ 8. 8 __ 2. 83 55—0T—100- _ _ Pegmatite _______________________ do ___________________________________________ 11. 2 _ _ 2. 45 Biotite schist _______________ 0.5 mile northeast of Hollis _________________________ 4. 6 1. 48 2. 32 Pegmatite __________________ 0.5 mile east of Hollis ______________________________ 5. 4 __ 2. 47 Biotite gneiss _______________ East flank of Jack Moore Mountain _________________ 3. 7 __ 2. 51 Pegmatite _______________________ do ___________________________________________ 5. 8 -_ 2. 27 Biotite gneiss _______________ 0.25 mile south of Mount Olivet Church ______________ 5. 0 . 22 3. 30 _____ do______-__________-___ 0.5 mile southeast of Mount Olivet Church---________ 3.8 __ 2.57 _ Toluca Quartz Monzonite- _ _- 1.6 miles east of Hopewell __________________________ 4. 3 . 76 2. 65 Biotite schist _______________ 1.5 miles southwest of Hopewell _____________________ 6. 5 __ 3. 55 _____ do_-_-_________________ 2.3 miles south-southwest of Hopewell--___--_______- 5.4 __ 2.55 NORTH CAROLINA The atomic ratio Ce/ (Nd + Y) is discussed with a larger group of ratios determined for monazite from the part of the Shelby quadrangle in Cleveland County. As early as 1895 augen gneiss and gneissic granite exposed in the South Mountains along the north bor- der of Cleveland County were observed to be monazite bearing (Mezger, 1895, p. 822). Crystalline rocks were mined for monazite at Hick- ory Creek and at Carpenter Knob in Cleveland County. Pegmatite-impregnated biotite schist and gneiss exposed at the L. U. Campbell monazite placer mine on Hickory Creek about 3 miles northeast of Shelby was found to contain from 0.03 to 1.10 percent of monazite. The high tenor in monazite led to an effort to mine the rock. In 1900 the British- American Monazite Co., later called the British Monazite Co., constructed a plant to crush the rock and recover mon- azite (Pratt, 1901, p. 31; 1907b, p. 118—119; Sterrett, 1907b, p. 1204—1205; 1908b, p. 281; Pratt and Sterrett, 1908a, p. 325; Keith and Sterrett, 1931, p. 10). After several years of mining, a shallow and irregular quar- ry 5—20 feet deep was opened for a length of 450 feet and a width of 24—75 feet. Rock having 0.4 percent or more of monazite was milled as ore, and no difficulty was experienced in obtaining a product consisting of 90—95 percent of monazite. Concentrates were re- ported to contain 7.01 percent of Th0; (Pratt, 1903, p. 182) . If the analyzed concentrates contained 90 per- cent of monazite, the results of these old determina- tions are in remarkably good agreement with a later analysis of a pure separate of detrital monazite from Hickory Creek at the site of the Campbell mine. The pure monazite contained 7.72 percent of Th0; (Mertie, 1953, p. 12). Several years of operation dis- closed that the amount of monazite-rich schist and gneiss was inadequate for further mining (D’Allier, 1906, p. 30), and in 1907 the company abandoned the bedrock property and sold their equipment (Pratt, 1908, p. 66). Output of the venture is not known. The rock from which the monazite was mined is bio- tite schist, biotite-sillimanite schist, and graphitic bio- tite gneiss more or less thoroughly impregnated with pegmatite and completely recrystallized. According to Sterrett (1907b, p. 1204—1205; 1908b, p. 281—282), the layers of rock that have the most monazite possess typ- ical augen structure owing to eye-shaped porphyro- blasts of feldspar and small lenticular bodies of peg- matite which range in size from about 0.25 to 2 inches. Layers having scant pegmatite and layers wholly com- posed of pegmatite contain less monazite than the por- phyroblastic layers in which appreciable micaceous 199 rock remains. All gradations exist from nonporphyro- blastic gneiss through porphyroblastic gneiss to peg- matite. Such gradation may be between separate lay- ers in the rock or between parts of the same layer. The monazite was said by Sterrett almost invariably to pos- sess crystal form with brilliant faces and sharp edges, but observation by the present writer of many hun- dreds of concentrates from rocks in this area shows that crystal faces and sharp edges are not present in many places on more than 10 percent of the grains, even on monazite from pegmatite. Sterrett observed that the monazite is generally free from inclusions, although he did find graphite in one crystal. Monazite is in contact with the various minerals making up the rock, but it is commonly surrounded by or included in plates of biotite and grains of quartz. Biotite foliae are not displaced around the monazite; a relation thought by Sterrett to indicate the replacement of biotite by monazite. The relations of monazite in rocks at the British- American Monazite mine were interpreted by Sterrett (1908b, p. 284—285) as indicating “either a gathering together of the proper elements from the original rock and their formation into monazite during recrystalliza- tion, or the introduction of the proper elements from external sources, along with the materials causing peg- matization.” In Sterrett’s opinion the most likely source of the monazite was solutions derived from sub- jacent intrusive rocks, but in the first possibility he entertained, he concisely stated the gist of the view held by the present writer. Locally monazite-rich lay- ers have certainly developed by pegmatization, as is shown in a following discussion, but the regional development of monazite-bearing rocks seems most likely to be related to the metamorphic process aban- doned by Sterrett. The other locality in Cleveland County where mona- zite was commercially extracted from crystalline rocks was the F. K. McClurd mine near Carpenter Knob in the extreme northeastern part of the county. Placer mining at the McClurd property disclosed weathered pegmatite-impregnated gneiss that contained about 0.3 pound of monazite per cubic yard (Sterrett, 1908b, p. 281). Saprolite of the gneiss was sluiced for monazite, and the monazite thus produced was marketed. Seem- ingly no notable output was obtained, because con- temporary accounts of activities at the McClurd mine are brief compared to statements about the British- American Monazite Co. Of course, the sluicing of saprolite was not unusual in itself; at some placers saprolite immediately underlying fluvial gravel was customarily dug and sluiced with the gravel (Sterrett, 1908b, p. 279). 200 The Carpenter Knob area of Cleveland County be- came the focus of several later investigations into the amount of monazite in crystalline rocks. Monazite was found in five samples of quartz monzonite exposed at Acre Rock quarry and elsewhere near Toluca in this area during 1945, 1947, and 1948 by Mertie (1953, p. 17—18, 24). Subsequently, exposures at the Acre Rock quarry were cited as the type locality for the rock named Toluca Quartz Monzonite (GriflEitts and Over- street, 1952, p. 7 7 9—7 82), and the general occurrence of monazite in it was indicated by Griflitts and Olson (1953a, p. 207—220). The most thorough examination of the distribution of monazite in rocks of the Carpen- ter Knob area was made in 1952 and 1953 by J. W. Whitlow of the US. Geological Survey assisted in 1952 by P. E. Myers. Whitlow measured the amount of monazite in 25 pairs of samples of saprolite and resid- ual soil from crystalline rocks exposed in the drainage basin of Knob Creek, a stream that rises on Carpenter Knob. The samples of residual soil were taken from positions immediately overlying samples of saprolite except for two which were unfavorably situated and had to be collected some tens of feet from the saprolite. According to Whitlow (written commun, 1954) sapro- lite with the most monazite is from Toluca Quartz Monazite and that with the least is from biotite schist (table 62). Monazite in the residual soil averages about three to four times the amount in saprolite, and locally saprolite with unobservable amounts of mona- zite forms residual soil that has a small quantity of monazite. The two unfavorably situated pairs of sam- ples included soils with less monazite than the underly- ing saprolite. This reversal in the usual pattern of residual enrichment was attributed to sampling error. Elsewhere in Cleveland County exposures of mona- zite-bearing rocks, principally Toluca Quartz Monzon— ite, observed by Mertie (1953, p. 17—18) between 1945 and 1948 include five localities in the Fallston area, one in the vicinity of Lawndale, two near Casar, one near Mooresboro, and four along tributaries to Brushy Creek northwest of Shelby. The amount of monazite in the crystalline rocks of the Shelby quadrangle, which covers 246 square miles in central and western Cleveland County and eastern Rutherford County, was investigated between 1948 and 1951 by R. G. Yates and associates of the US. Geo- logical Survey (Overstreet, Yates, and Griflitts, 1963a). Heavy-mineral concentrates were panned from 1,241 samples of saprolite representing the main lithologic units in the quadrangle, 5 samples of milled vein quartz, and 300 samples of residual soil. The kinds and amounts of resistate heavy minerals were THE GEOLOGIC OCCURRENCE OF MONAZITE TA_BLE 62.—Amount of monazite in saprolite and residual soil m the drainage baszn of Knob Creek, Cleveland County, N.C. [Tenors computed by J. W. Whitlow (written commun., 1954) from concentrates analyzed mineralogically by M. N. Girhard, H. B. Groom, Jr., R. P. Marquiss, O. J. Spengler, Jerome Stone, and E. J. Young] Saprolite Residual soil Monazite Monazite Lab. No. (11) per cu Lab. No. (lb per cu yd) yd) Toluca Quartz Mennonite 109614 _____________ 0. 16 109605 ____________ 0. 19 98942 _____________ . 51 31 ____________ 1. 16 114332 _____________ 05 33 ____________ . 31 37 _____________ 13 38 ____________ 20 62 _____________ 11 63 ____________ 18 69 _____________ 11 7O ____________ 55 72 _____________ 10 73 ____________ 39 Average _____ 17 Average _____ . 43 Biotite Gneiss 88529 _____________ 0. 25 88530 ____________ 0. 42 35 _____________ . 13 36 ____________ . 87 114374 _____________ . 05 114375 ____________ . 04 80 _____________ . 01 109699 ____________ . 09 82 _____________ . 03 114383 ____________ . 08 Average _____ . 09 Average _____ . 30 Biotite Schist 114334 _____________ 0. 19 114335 ____________ 0. 23 39 ____________ . . 23 . 27 . 05 . 04 Average _____ . 16 114343 _____________ 0. 24 48 _____________ . 05 . 07 . 25 . 23 . 58 . 27 . 09 Average _____ . 08 Average _____ . 22 determined in the concentrates. About two-thirds of the soil samples, all the vein quartz, and 1,033 concen- trates from saprolite came from the part of the quad— rangle in Cleveland County, but results of the study were tabulated for the quadrangle as a whole; there- fore, they cannot be separated by county. Concen- trates were panned from saprolite of Toluca Quartz Monzonite, microcline-oligoclase-quartz pegmatite gen- etically related to the Toluca, biotite gneiss, biotite schist, biotite schist impregnated with pegmatite, sil- limanite schist, and sillimanite schist impregnated with NORTH CAROLINA 201 TAB LE 63.—Estirnated abundance of monazite in crystalline rocks in the Shelby quadrangle, Cleveland and Rutherford Counttes, N C [Recalculated from Overstreet, Yates, and Griflitts (1968, table 1)] Number of concentrates Monazite as weight percentage of host rock in samples giving concentrates with 1 percent or more monazite Total Monazite Monazite less examined absent than 1 percent of concentrate Minimum Maximum Average Toluca Quartz Monzonite ___________________ 96 1 2 0. 00002 0. 04 0. 004 Microcline—oligoclase-quartz—pegmatite ________ 329 18 22 . 00002 . 08 . 006 Biotite gneiss ______________________________ 59 6 6 . 00002 . 06 . 006 Biotite schist ______________________________ 198 49 42 . 00002 . 008 . 001 Biotite schist and pegmatite _________________ 303 46 31 . 00002 . 04 . 004 Sillimanite schist ___________________________ 150 12 28 . 00008 . O6 . 002 Sillimanite schist and pegmatite ______________ 106 4 13 . 00002 . 01 . 002 Vein quartz ________________________________ 5 3 1 __________________ . 01 pegmatite. In the original tabulations the amounts of heavy minerals were estimated as volume percentages of the saprolite, but in table 63 monazite is recalculated to weight percentage of the rock. The pegmatite-bearing rocks are intimate mixtures of schist and all degrees of lit-par-lit layering of mi- crocline-oligoclase-quartz pegmatite. The pegmatite- bearing schists occur as wellddefined zones mostly per- ipheral to masses of Toluca Quartz Monzonite, and the pegmatite has been interpreted to be a diflerentiate from the Toluca (Overstreet, Yates, and Griffitts, 1963b). Owing to the relatively large average amount of monazite in pegmatite and the high percentage of bodies of pegmatite that contain monazite (88 per- cent), schist impregnated with pegmatite is more com- monly monazite bearing than pegmatite-free schist. Biotite schist permeated with pegmatite contains on the average of four times as much monazite as biotite schist lacking pegmatite. The presence of pegmatite does not seem to increase the amount of monazite in sillimanite schist, but it does increase the frequency with which samples of the schist are monazite bearing. Monazite occurs in more than trace amounts (1 percent of the concentrate or more) in 63 percent of samples of sillimanite schist and 54 percent of samples of bio- tite schist, but where pegmatite is present the percent- age of monazite-bearing samples increases to 83 per- cent for the sillimanite schist and 75 percent for the biotite schist. Greater amounts of monazite in the lit— par-lit schists may also be in part caused by increase in the number of centers of crystallization of meta- morphic monazite resulting from local geothermal rise in schists adjacent to pegmatite and quartz monzonite (Overstreet, Yates, and Grifiitts, 1963a). The estimated abundance and distribution of mon- azite in the metasedimentary rocks was shown by con- tours on a map of the Shelby quadrangle (Overstreet, Yates, and Grifiitts, 1963a, p]. 1). The main trend of high-value contours for monazite was found to occupy a broad arcuate zone that extends northward from Boiling Springs to Lattimore in Cleveland County, thence northwest toward Jack Moore Mountain in Rutherford County. The zone approximately follows an area underlain by the thickest sequence of silliman- ite schist in the quadrangle. A narrow and well- dcfined zone occupied by high-value contours for mon- azite is parallel and east of the main monazite high. It leads northeastward through Cleveland County from Poplar Springs Church by way of Dover Mill to Zion Church, thence northwestward by Ramseur School to the First Broad River 2 miles northeast of Polkville. This high corresponds to a narrow band of sillimanite schist and an adjacent band of biotite schist. Local monazite highs coincide with either sillimanite schist or biotite schist around several sills of Toluca Quartz Monzonite, of which the most noteworthy high is between Fallston and Flat Rock School a few miles south of Carpenter Knob and Toluca. The local highs seem to be related to migmatization of wallrock schist by lit-par-lit introduction of mona- zite—bearing quartz monzonite and pegmatite. The two major zones of monazite highs are clearly related to monazite in sillimanite schist. As was stated in the section on hypotheses of origin, the writer interprets the monazite in the unintruded schists to be a meta— morphic mineral formed when the sedimentary rocks were metamorphosed to the sillimanite-almandine sub- facies. The average amount of thorium oxide in monazite from 16 samples of sillimanite schist in the part of Shelby quadrangle in Cleveland County was deter- mined by Murata and Rose of the US. Geological Sur- vey to be 4.7 percent (Overstreet, Yates, and Griflitts, 1963a, table 4). A nearly identical average was found for 28 samples of biotite schist in the part of the quad- rangle in Cleveland County (table 64), and, if the three samples from Rutherford County (table 61) are added, the average amount of thorium oxide in mona- 202 zite from biotite schist is virtually identical to that of monazite from sillimanite schist in the quadrangle. Virtually identical averages were found for the atomic ratio Ce/ (Nd + Y) of monazite from silliman- ite schist and monazite from biotite schist (table 64). If the ratios found for monazite from biotite schist in Rutherford County are included and the two unusually high ratios dropped (3.55 for a sample from Ruther- ford County and 4.25 for a sample from Cleveland County), the average of 29 samples of monazite from biotite schist is 2.48. The great similarity in the aver- age amount of thorium oxide and the atomic ratios is interpreted by the writer to indicate that monazite formed under similar conditions in both types of schist. A possible interpretation of the significance of the average atomic ratio is discussed a little farther along TABLE 64.—Tharium and rare—earth composition of monazite from saprolz’te of sillimanite schist and biotite schist exposed in the Shelby quadrangle in Cleveland County, N.C'. [Quantitative spectrochemical analyses by K. J. Murata and H. I. Rose, J r., U.S. Geol. Survey, 1955] Atotrinic Th02 I“ ° Lab. N 0. Location (percent) Ce (Nd+Y) Sillimanite schist 138526 __________ 4.2 miles north-northeast of Polkville ________ 9. 0 2. 30 27 __________ 0.4 mile north-northeast of Pleasant Hill 4. 8 2. 32 Church. 3 miles north of Polkville ................... 4.0 2. 40 2.4 miles west of Polkville _______ _ 4. 2 2. 65 1.8 miles northeast of Lattimore.... 4. 8 2. 55 1.7 miles east-southeast of Lattimor 4. 2 2. 47 3 miles south of Polkville ___________ 3. 4 2. 35 1.1 miles West-northwest of Lattimore _ 4. 8 2. 65 2 miles north of Lattimore _____________ - 5.8 2. 57 1.3 miles northwest of Zion Church... . 3. 4 2. 51 1 mile southeast of Double Shoals ...... 4. 8 2. 50 1.8 miles scum-southwest of Lattimore ...... 4. 6 2. 47 1.5 miles north-northeast oi Boiling Springs__ 4. 5 2. 55 1.5 miles southwest of Shelby _______________ 3. 9 2. 45 1.3 miles southeast of Shelby ______________ 5.1 2. 63 Dover Mill _________________________________ 4. 3 2. 57 . . ______ _ 4. 7 2. 50 Biotite schist Dover Mill _________________________________ __- o ________________________ _ Cadish Church ( neolnton quad. _ 0.5 mile northwest of Kistler Union C u.r 3.5 miles northwest of Polkville- ___ Mooresboro ________________________ _ -.- 3 miles north of Dover Mill _________________ 3.9 miles north-northwest of Dover Mlll..-.. 4.3 miles northwest of Dover Mill____ _. 2 miles west-northwest of Dover Mill 1.3 miles northeast of Lattimore.__. 1.3 miles east-southeast of Lattimore 4.3 miles northeast of Lattimore. .._ 0.6 mile east of Lattimore ________ ____ 0.4 mile north of Lattimore __________________ 0.8 mile northeast of Boiling Springs ........ 2.8 miles east-northeast of Boiling Springs _. Dover Mill ______________________________ Cadiish Church (Lincolnton quad __ mamamhmqmmwwww aquwwwww NOIHOQUIUIOOIKIUIOKIQOOCD NICDIIOhAOUfi cocoa: pate a: do__ - _____________ 1.7 miles north of Lattimor 4.2 miles northeast of Lattimore 1 8 . 50-W—l 1 5 (8) 50-W-14OS ______ Average. _ _ _ _ . P ?9P99PPN@?PW?PPPPF?99P9PPPPP m mwcoHflmHwwwmohmamwuwwmcmomoa 12. 49 1 The unusual ratio of sample 139898 not included. THE GEOLOGIC OCCURRENCE OF MONAZITE after the ratios for monazite from the other rocks has been discussed. . A little information is available about the amount of U308 in monazite from the schists. Monazite from sillimam'te schist exposed 0.4 mile north of Pleasant Hill Church in Cleveland County was found by Car- men Johnson and Blanche Ingram (written commun., 1955) of the U.S. Geological Survey to contain 0.45 percent of U308. Monazite from biotite schist at a locality 0.5 mile northwest of Kistler Union Church in Cleveland County was shown by Johnson and Ingram to contain 0.29 percent of U308 . No relation has been discerned between the amount of uranium in the mona- zite and the rocks in which the monazite occurs. Biotite gneiss formed by high-grade metamorphism of graywacke and volcanic rocks, possibly dacite, occurs close to sills of Toluca Quartz Monzonite in the Shelby quadrangle (Overstreet and Griflitts, 1962, map; Overstreet, Yates and Griifitts, 1963b). The gneiss is coarse grained and rich in microcline. At some places it seems to have been feldspathized by the quartz monzonite, but the actual origin of the rock is obscure. Monazite from the gneiss tends to be inter- mediate in composition between that from schists and that from Toluca Quartz Monzonite and pegmatite. Nine samples of monazite from the gneiss have been analyzed and found to average 5.4 percent of Th02 (Overstreet, Yates, and Grilfitts, 1963a, table 4). Six of these samples have an average atomic ratio Ce/ (Nd +Y) of 2.57 (K. J. Murata and H. J. Rose, Jr., written commun, 1955), but the other three have individual ratios of 3.10, 3.30, and 3.50, thereby raising the group average to 2.81. Five of the samples came from the part of the quadrangle in Rutherford County, and their composition is given in table 61. Four are from Cleveland County. They are richer in thorium oxide and have a larger atomic ratio (table 65) than monazite from biotite gneiss in Rutherford County, possibly because the gneiss in Cleveland County has been altered by Toluca Quartz Monzonite. Each of the sampled layers of gneiss in Cleveland County is in contact with sills of quartz monzonite. In its high con- tent of thorium the monazite from biotite gneiss in Cleveland County is more like monazite from pegma- tite-impregnated schist and gneiss in the quarry of the British Monazite Co. at the old Campbell mine on Hickory Creek than it is like monazite from unpegma- tized schists. The percentage of thorium oxide (Dutra and Murata, 1954) and the atomic ratios have been deter- mined by K. J. Murata and Harry Rose, Jr., of the U.S. Geological Survey, for 23 samples of monazite from Toluca Quartz Monzonite and for 43 samples NORTH CAROLINA from pegmatite exposed in the Shelby quadrangle and vicinity. Results of this work disclosed that monazite from the two rocks has identical averages of 6.1 percent of ThOZ (Overstreet, Yates, and Griffitts, 1963a, table 4). Average atomic ratios of Ce/ (Nd+Y) are slightly difl'erent: the ratio for 23 samples of monazite from the Toluca is 2.54 and for 43 samples of pegmatite is 2.60. From the quartz monzonite 21 samples were taken at localities in Cleveland County, and from the pegmatite 40 were taken (table 66); they have virtually identical average amounts of thorium oxide and atomic ratios as the complete suite of samples from the quadrangle. For the single sam— ple of monazite from a quartz vein the tenor in thorium oxide is identical to that of monazite from the quartz monzonite and pegmatite, but the atomic ratio is less TABLE 65.—-Thorium hand rare-earth composition of monazite from saprolite of biotite gneiss in Cleveland County, N.C. [Quantitative spectrochemical anal ses by K. J. Murata and H. J. Rose, Jr., U.S. Geo . Survey, in 1955] Atotrinic Th0: ’3 ° Lab. No. Location (percent) Ce (N (H Y) 138558 __________ 1 mile northeast oi Kistler Union Church--.. 6. 7 2. 50 564 . Boiling Springs _____________________________ 6. 2 3. 10 56 . 4 miles southwest of Shelby ....... 6. 0 2. 80 139902 __________ Cadish Church (Lincolnton quad.) .......... 8. 8 2. 67 Average. . ..... 6. 9 l 2. 62 ‘ The unusual ratio of sample 138564 not included. TABLE 66.—Thorium and rare-earth composition of monazite from sapvolite of Toluca Quartz Monzonite and microcline— oligoclase-quartz pegmatite and from unweathered vein quartz emposed in Cleveland County, N 0 [Quantitative spectrochemical analyses by K. J. Murata and H. J. Rose, In, U.S. Geol. Survey, in 1955] 203 TABLE'66.—Thorium and rare-earth composition of monazite from "saprolite of Toluca Quartz Moneonite and microcline— oligoclase-quartz pegmatite and from unweathered vein quartz exposed in Cleveland County, N.C.—-Continued. Atomic Th0: ratio Lab. No. Location (percent) Ce (N d+ Y) Microcline-oligoclase-quartz pegmatlte 36 64 65 66. . - o ....................................... 138572-- 0.7 mile southwest of Kistler Union Church. 73. - 1.4 miles east of Kistler Union Church ...... 74. . 1.9 miles east of Polkville ............... .- 77.- 1.4 miles southwest of Zion Church ..... 78- - 2.2 miles west-northwest of Dover Mill. 79.. 2 miles east-southeast of Lattimore ..... 80. - 1.3 miles northwest of Zion Church_. 81. . . 0.2 mile north of Double Shoals ..... 82. - . 1.8 miles south-southwest of Zion Ch 83 - 2. 4 miles east of Boiling Springs NNNPPPPNNNWMPNNFNNNPPNNNNNPNPNNPNPNPNNN umawNuo-usouo OI ~16: ~14“ 6:03 usooq «onwards»; 9 a NVQQPPVQQQ99999999999?9N?P9SPNP99WN9999 O #- oquswmmaqowomocowwwummmcwomqwr‘kuqmcovdozouc .-:.-do ....................................... 50—W—140A ..... 2.8 miles west-northwest of Zion Church- -.. 50—W—140B ..... -..- o ....................................... 54-5388W 1 ...... Quarry at Acre Book, 1.7 miles southwest of ’I‘oluca (Casar quad.) ... -- 2. 50 Average. . ............................. —-— 3 2. 60 Vein quartz 1383771 2.. miles northeast oi’ Boiling Springs ....... 6. 1 2. 27 Atomic ratio Lab. No. Location Th02 Ce (percent) —— (Nd+ Y) Toluca Quartz Monzonite 135570B ......... Cadish Church (Lincolnton quad.) .......... 5. 4 2. 47 700 -.-- n 6.7 2. 78 6.1 2. 24 5. 7 2. 60 5. 8 2. 53 6. O 2. 55 6. 5 2. 75 6. 2 2. 63 ---- ------ 5. 7 2. 60 ----do--- 6. 5 2. 63 1. 3 mile 7. 3 2. 30 Church. 0.6 mile east-southeast of Pleasant Hill.. 7. 2 2. 20 Church. 2. 7 miles south-southwest o! Polkville ....... 4. 3 2. 33 3 miles east-northeast of Lattimore.-.. .- 5.1 2. 60 Cadish Church (Lincolnton quad.) .......... 6. 7 2. 55 6. 6 2. 45 6.4 2. 80 6. 6 2. 57 6. 6 2. 57 03... ...- 0 ... 6.1 2 55 54-537sz ...... Quarry at Acre Rock, 1.7 miles southwest .. 5. 3 2. 26 of Toluca (Casar quad.). Average.. 6 1 2.52 See footnotes at end of table. =13 111%: distiiisiiziiriiiiggli, sample 139920 not included. than the average ratios for monazite from the other rocks. The atomic ratios probably provide evidence as to the origin of monazite in the schists, quartz mon- zonite, and pegmatite. The ratio of the sample from vein quartz does not fit the pattern shown by the mona- zite from the main rock units, but it is very similar to the ratios of monazite from the Cherryville Quartz Monzonite, a rock that crops out to the east of the quadrangle. The composition of rare earths plus thorium oxide precipitated from solutions of seven samples of mona- zite from Rutherford County and Cleveland County was determined spectrochemically by Murata, Rose, Carron, and Glass (1957, p. 148). In table 67 the values published by Murata, Rose, Carron, and Glass have been recalculated to percentages of oxides in 204 TABLE (ET—Chemical analyses of rare earth plus thoria precipi- tates from monazite, Rutherford and Cleveland Counties, N.C. [Analyses recalculated from Murata, Rose, Carron, and Glass (1957, p. 148)] Rutherford County Cleveland County 138544 138560 54— 55—0 T— 138538 54— 54- 5398W 100 537SW 53SSW 14.8 16.2 14.8 10.1 15.3 13.9 14.1 30. 0 33. 7 30. 1 23. 3 30. 2 29. 5 29. 9 3.0 2.9 2.8 2.9 2.8 3.4 3.2 11.3 9.6 9.4 9.5 11.7 12.1 11.1 1.6 .8 1.2 2.6 1.6 2.2 2.1 . 5 . 3 . 5 2. 1 1. 3 . 8 . 7 2. 4 . 1 . 6 2. 3 . 9 . 4 . 4 5.4 4.4 8.8 11.2 4.5 5.3 6.4 Total ............ 69. 0 68.0 68. 2 64. 0 68. 3 67. 6 67. 9 138544. Biotite schist. 138560. Biotite gneiss. 54—5398W. Toluca Quartz Monzonite. 55—OT—100. Pegmatite. 138538. Sillimanite schist. 54—537SW. Toluca Quartz Monzonite. 54—5388W. Pegmatite. monazite from data furnished by H. J. Rose, Jr. (written commun., 1959). The content of thorium oxide and the Ce/ (Nd+Y) atomic ratios are less in monazite from schists than in monazite from quartz monzonite in the parts of Rutherford County and Cleveland County covered by the Shelby quadrangle: Atomic Number of Th02 ratio Source of monazite analyses of (Avg Ce monazite percent) (N d+ Y) Biotite schist ___________________ 31 4. 8 1 2. 48 Sillimanite schist ________________ 16 4. 8 2. 49 Biotite gneiss ______________ _ 9 5. 4 2 2. 57 Toluca Quartz Monzonite- _- 23 6. 1 2. 54 Pegmatite ______________________ 43 6. 1 2. 60 Quartz vein _____________________ 1 6. 1 2. 27 1 Average of 29 analyses. 2 Average of 6 analyses. Rare earths in monazite from the pegmatite, as indi- cated by the atomic ratios, are more highly fractionated than rare earths in monazite from the quartz monzo— nite. Systematic variations in rare earths in monazite from the quartz monzonite and pegmatite have been tentatively attributed by Murata and associates (1953, p. 296—299; 1957, p. 148—151) to repeated fractional precipitation of the rare—earth elements in a differen- tiating magma in which substantial but undetermined parts of the rare earths are probably captured by other minerals such as xenotime, biotite, and garnet. Biotite and garnet from the Toluca Quartz Monzonite were found by K. J. Murata (written commun., 1954) to contain lanthanum and yttrium. Both the biotite and garnet contained more yttrium in relation to lanthanum than monazite from the Toluca. Murata interpreted these relations to indicate that a major factor in the fractionation of rare earths in nature THE GEOLOGIC OCCURRENCE 0F MONAZITE was probably the selective deposition of yttrium earths in silicate minerals; this deposition resulted in the enrichment of residual fluid in cerium as successive rocks differentiated out of the magma (K. J. Murata, written commun., 1954). Monazite from the schists has smaller Ce/ (N d+ Y) atomic ratios than monazite from the quartz monzonite and pegmatite, and this fact indicates that the mona- zite in the schists has on the ave-rage more of the less basic and less soluble (Carron and others, 1958, p. 268) rare earths than the monazite in the quartz monzonite and pegmatite. These less basic elements contribute to a contraction of the unit cell of the monazite (Murata and others, 1957 , p. 150) ; thus, monazite in the schists has a smaller unit cell than monazite in the quartz monzonite and pegmatite. If monazite in the schists had been deposited by solutions derived from the quartz monzonite, it might be expected that these solu- tions would be more highly fractionated than the quartz monzonite and that the monazite deposited by them would have larger average atomic ratios than monazite from the quartz monzonite; for the same reasons monazite in the schist would be expected to have a larger unit cell than monazite in the quartz monzonite. An interesting possible explanation for these seeming conflicts is that the regional metamorphism which formed the schists may also have produced the quartz monzonite as a metamorphic differentiate. As exposed in the Shelby quadrangle, the Toluca Quartz Monzo- nite consists of concordant intrusive bodies which con- tain sparse altered inclusions of the wallrocks (Over- street, Yates, and Griflitts, 1963a). It was formed at depth and migrated upward. That the Toluca Quartz Monzonite could migrate and the schists could not may be important in the control of the composition of the monazite and the size of its unit cell. Under the influence of high—grade regional metamorphism pos- sibly the more basic rare earths (lanthanum, cerium, and praseodymium), which are most soluble, were preferentially mobilized and migrated with compo- nents that were surplus to the metamorphic mineral phases of the schists. The less basic rare earths (neodymium, gadolinium, and yttrium), which are less soluble, were preferentially retained in the schists. Crystallization of the more basic rare earths in the mobilized parts of the metamorphic rocks gave rare- earth-bearing biotite with relatively more yttrium than lanthanum and also monazite with a large Ce/(Nd+Y) atomic ratio and large unit cell. Crystallization of the less basic rare earths remaining in the Immobilized schists gave monazite with a small Ce/ (Nd+ Y) atomic ratio and small unit cell. Relations of the rare earths NORTH CAROLINA in the biotite and garnet in the schists are not known. Monazite with large atomic ratio and unit cell seems to be compatible with a relatively mobile phase, whereas monazite with small atomic ratio and unit cell seems to be compatible with the static phase of the metamorphic rocks. Differentiation and fractional crystallization in the mobile phase probably would lead to pegmatites having monazite with highly frac— tionated rare earths. Monazite from the biotite gneiss possesses hybrid average abundance of thorium oxide and Ce/ (Nd+Y) atomic ratio that places it between monazite from the schists and monazite from the pegmatite related to the Toluca Quartz Monzonite. The origin and rela- tions of the biotite gneiss are poorly understood, and no satisfactory explanation is available for the com- position of the monazite. At most places the gneiss seems to have been altered by the Toluca and pegma- tites related to the Toluca. Possibly monazite from the gneiss is polygenetic, being in part formed in place in the gneiss and in part crystallized from stringers of pegmatite and Toluca Quartz Monzonite. The single sample of monazite from vein quartz con- tains identically the same amount of thorium oxide as the average of monazite from the Toluca Quartz Monzonite and pegmatite related to the Toluca. Its Ce/(Nd+Y) ratio of 2.27 is very different from the average for monazite from the Toluca and pegmatite, although about six individual analyses in the group disclosed similar ratios. Without other analyses of monazite from quartz veins in the area it is not certain if this ratio is unusually low for monazite from these veins or if it is about average. Because the vein also contains accessory rutile and zircon that resemble those minerals in Toluca Quartz Monzonite the vein was interpreted to be genetically related to the Toluca (Overstreet, Yates, and Griflitts, 1963a). The amount of thorium oxide and the atomic ratio, however, closely resemble those of monazite from the much younger Cherryville Quartz Monzonite which crops out to the east of the Shelby quadrangle along and outside the east edge of the western monazite belt (Grifiitts and Overstreet, 1952, p. 7 83—7 86). It may be possible that this quartz vein was derived from the Cherryville. The Cherryville Quartz Monzonite is a crosscutting pluton which is partly outside the east edge of the western monazite belt, but because of its close relation to the belt it is mentioned here. Most specimens of the Cherryville Quartz Monzonite and mica-bearing peg— matites related to it lack monazite (J ahns and others, 1952, p. 31; Griffitts and Olson, 1953a, p. 218), but in eastern Cleveland County two samples from a locality in the Lincolnton quadrangle and one from the Kings 205 Mountain quadrangle were found to have monazite (Overstreet, Yates, and Griifitts, 1963a, table 4). Analyses of the three specimens of monazite disclosed an average of 6.4 percent of ThO2 and an average Ce/ (Nd+ Y) atomic ratio of 2.34: (table 68). The single determination of uranium showed that monazite from the Buffalo Creek locality has more uranium than any other in the United States. Pegmatite probably related to the Cherryville Quartz Monzonite and exposed 5.6 miles east of Buffalo Creek on the western outskirts of Kings Mountain, Cleveland County, contains monazite (Mertie, 1953, p. 17). The pegmatites of the tin-spodumene belt in Cleve- land, Gaston, and Lincoln Counties are for the most part barren of monazite and are generally thought to lie just to the east of the east edge of the monazite belt (J ahns and others, 1952, p. 31). Inasmuch as they are closely associated spatially with and may be genetically related to the Cherryville Quartz Monzonite, they are mentioned here. The spodumene pegmatite mined by the Foote Mineral Co. just south of Kings Mountain in Cleveland County was said to contain sparse mona- zite which was recovered as a byproduct along with cassiterite, columbite, pyrrhotite, pyrite, and rutile (Hudspeth, 1952). Apparently these minerals are fine grained and disseminated through the pegmatite. They are estimated by Hudspeth to make up altogether about 0.2 percent of the spodumene ore. Beryl, apatite, and tourmaline are also present in the pegmatite. LINCOLN COUNTY AND GASTON COUNTY Monazite is an accessory mineral in Toluca Quartz Monzonite exposed in the extreme northwest corner of Lincoln County (Overstreet, Whitlow, White, and Gritfitts, 1963). None of the occurrences in the Toluca is a possible commercial source of monazite, but placers in streams rising on the quartz monzonite and schists TABLE 68.—-Thom’um, uranium, and rare-earth composition of monazite from the Cherryville Quartz Monzonite exposed in Cleveland County, N.C. [Quantitative spectrochemical analyses for thorium and determination of Ce/(Nd+ Y) atomic ratio by K. J. Murata and H. J’. Rose, Jr.; chemical analysis for uranium py Blanfihe Ingram, U.S. Geol. Survey, in 1954—55. Sumbol used: —, not de- ermme Atomic Th0; U30: ratio Lab. No. Location (percent) (percent) Ce (Nd+ Y) 53—BE-3 1.. _ _____ Buffalo Creek 2.3 miles east- 5. 6 2. 34 2. 36 southeast of Elizabeth Church. 135556 2 ............... do .......................... 6. 6 —- 2. 19 49 1 __________ Grover __________________________ 6. 9 - 2. 49 Average._._ __________________________________ 6. 4 — 2. 34 1 Saprolite. 3 Unweathered rock. 206 in this area were mined for detrital monazite in the late 1800’s and early 1900’s. The Cherryville area in northwestern Gaston County has been cited as a source for monazite, but details have not been given (Drane and Stuckey, 1925, p. 19; Bryson, 1927, p. 15—16). The area is the type locality for the Cherryville Quartz Monzonite which contains few accessory minerals and at Cherryville is not known to be monazite-bearing (Griflitts and Over- street, 1952, p. 783—786). The references to Cherry- ville may relate to monazite placers formerly worked several miles to the west of the town (Sterrett, 1908b, p. 274), or Drane and Stuckey may have found a place where the Cherryville Quartz Monzonite was monazite bearing. Inasmuch as two such localities are known in Cleveland County, it is possible that others are present in Gaston County and Lincoln County. In general, however, the pluton of Cherryville Quartz Monzonite lies on the east side of and outside the western mona- zite belt in the Piedmont. OUTLYING LOCALITIES IN THE PIEDMONT PROVINCE BETWEEN THE WESTERN AND EASTERN MONAZITE BELTS Several scattered occurrences of monazite have been reported from that part of the Piedmont physiographic province of North Carolina that is between the western and eastern monazite belts as defined by Mertie (1953, pl. 1). At some localities the monazite is present in crystalline rocks. Elsewhere it is found in stream sediments and may have been transported many miles to its present site. Because the geology of the few detrital deposits in these outlying deposits is closely related to the geology of the crystalline rocks in the Piedmont, they are here discussed with occurrences of monazite in crystalline rocks. GASTON COUNTY Heavy sand from gold placers south of Crowders Mountain, Gaston County, was reported to contain monazite (Genth, 1891, p. 7 7—7 8, 86), but apparently it is not present in great abundance. The source is unknown. Most of the rocks are fine-grained low— grade schists which were sampled at a number of places and found to be free of monazite (W. R. Griflitts, oral commun., 1952; D. B. Potter, oral commun., 1953). It is remotely possible that this monazite has been carried down from former higher level surfaces of erosion where it had been deposited by streams that reached 10 miles or so into the western monazite belt. More likely this monazite was derived from as yet unrecognized monazite—bearing rocks ex— posed at the present level of erosion in the vicinity. MECKLENBUBG COUNTY Todds Branch in Mecklenburg County was reported by Genth (1862, p. 204; 1891, p. 77—78; Eng. and THE GEOLOGIC OCCURRENCE OF MONAZITE Mining Jour., 1888, p. 2) to have been the source of one crystal of monazite about one-quarter of an inch long, one-eighth of an inch wide, and a little less than one-eighth of an inch thick. The crystal was yellowish brown, had a specific gravity of 5.203, and seemed to be waterworn and somewhat rounded. It was found in auriferous concentrates associated with garnet, zircon, and diamond. The Todds Branch occurrence has been frequently mentioned in the literature for both monazite and diamond, but the name of the stream has not been shown on published maps. According to J. L. Stuckey, State Geologist of North Carolina (written commun., 1962), Todds Branch lies a few miles to the northwest of Charlotte and is the easternmost of three small streams between the village of Paw Creek on the west and Toddville on the east. Todds Branch is one of the headwater tributaries to Paw Creek, which enters the Catawba River west of Charlotte. Rocks in the Todds Branch area are dominantly granite, gabbro, and diorite; pegmatite is present but uncommon. The large size of the monazite crystal most likely indicates that the crystal came from pegmatite. Perhaps it had a local source, but possibly the monazite was brought from the western monazite belt by an ancestral Catawba River when that stream was at an older high erosional level. Detritus left at that level when the Catawba carved its present valley might have been reworked by Todds Branch, and any monazite present in the old alluvium would have been deposited in the new sediment. With presently avail- able data it is not possible to determine the origin of the monazite reported at this locality. Detrital monazite is present in five magnetite- and epidote-rich concentrates from alluvium in small streams southwest of Newell in Mecklenburg County (Henry Bell, 3d, oral commun., 1963). Transparent pale-yellow to translucent brownish-yellow grains make up 1—5 percent of the concentrate. Many grains are subhedral crystal fragments that are scarcely abraded. The source of the monazite seems to be coarse-grained granite that underlies the drainage basins, but the granite has not been sampled for monazite. ROWAN COUNTY AND DAVIDSON COUNTY Fifty-seven concentrates from alluvium in the upper reaches of small streams tributary to the Yadkin River in the High Rock quadrangle in Rowan County and Davidson County, were found by White and Strom- quist (1961) to contain heavy minerals not present in the low-grade metamorphic rocks drained by the streams. The rocks consist of argillite, weakly meta- morphosed tuff and flows of rhyolitic to andesitic NORTH CAROLINA composition, and intrusive diabase and gabbro. No- where in the area of the quadrangle do the rocks exceed the greenschist facies. Index minerals of amphibolite facies, including staurolite, kyanite, al- mandine, and sillimanite, are in the concentrates. Monazite is present in 13 concentrates, and zircon in 35. Neither of these minerals has been observed in the rocks in the quadrangle. The source of the monazite, zircon, and other anomalous minerals was interpreted by White and Stromquist to be rocks of the middle and upper amphi— bolite facies exposed 30 miles or more to the north- west, particularly in the vicinity of Stokes County and Surry County. It is thought that after erosion from appropriate gneiss, schist, and granite the anom— alous heavy minerals, including monazite, were trans- ported southeastward by an ancestral Yadkin River and deposited in alluvium along former courses of the stream. Relicts of this high-level alluvium reached by the small streams that were sampled add the anom- alous heavy minerals to the concentrate. There is no local source for the detrital monazite. ORYSTALLINE ROCKS IN THE EASTERN MONAZITE BELT IN THE PIEDMONT PROVINCE Monazite was discovered by Mertie in 1949 as an accessory mineral in granite in the eastern part of the Piedmont province about 114 miles southeast of Rolesville, Wake County, some 15 miles northeast of Raleigh, NC. (Mertie, 1953, p. 15, 18, pl. 1). From Rolesville the monazite—bearing rocks were traced north-northeastward for 200 miles to the vicinity of Fredericksburg, Va., and to this heretofore unknown zone Mertie assigned the term “eastern monazite belt.” Rocks in the North Carolina segment of the eastern monazite belt were the source for nine monazite- bearing concentrates in addition to the discovery sample (Mertie, 1953, p. 18-19). Elsewhere in Wake County, monazite occurs as an accessory in granite exposed 1.1 miles southwest of Garner and in granite at two localities near Milburnie on the Neuse River east of Raleigh. Monazite is present in granite ex- posed at three localities southwest of Louisburg in Franklin County. Granite cropping out 3.6 miles southeast of Norlina and 8 miles southwest of Warren- ton in Warren County contains accessory monazite. The monazite localities in the area between Raleigh and Louisburg are along the western and central part of a north-northeasterly elongate mass of quartz mon- zonite (Parker and Broadhurst, 1959, p. 1—5). Flank- ing the pluton on its west side is a thick sequence of regionally metamorphosed sedimentary rocks. These rocks are at the kyanite-staurolite subfacies. The metamorphic grade decreases progressively toward the 207 west and reaches the lowest subfacies of the green- schist facies at a point about 12 miles west of the pluton. These metasedimentary rocks were said by Parker and Broadhurst (1959, p. 5, 13—14) to grade eastward into the quartz monzonite, which they regard as possibly the culmination of the metamorphic changes affecting the sedimentary rocks. It is along this zone of possible metamorphic culmination that the monazite occurs. This monazite has not been analyzed; thus, whether it contains moderate amounts of thorium oxide, as would be expected if it formed at the kyanite—staurolite grade, is unknown. STREAM DEPOSITS IN THE PIEDMONT PROVINCE The history of the discovery and mining of detrital monazite in the Piedmont physiographic province of North Carolina was reviewed in the introductory sec- tion on North Carolina. In this section on stream deposits, emphasis is placed on descriptions of specific localities, analytical data on placer monazite, and esti- mates of tenors and reserves of fluviatile deposits. Data on the placers are summarized in geographic order similar to that followed for the discussion of monazite in crystalline rocks in the Piedmont. The close relation between the kind of source rock and the tenor and composition of detrital monazite, pointed out in the section on “Hypotheses of origin,” is given further emphasis. The known placer deposits in the Piedmont of North Carolina are restricted to the area of the western monazite belt as defined by Mertie (1953, pl. 1) . They are in locally derived fluvial sediments that cover the floors of shallow, narrow valleys occupied by perennial streams and underlain by weathered crystalline rocks (Sterrett, 1908b, p. 27 9—281; Overstreet, Theobald, and Whitlow, 1959, p. 7 09—713). The fluvial sediments are well bedded, poorly graded, and unconsolidated. Throughout the monazite belt they have much the same stratigraphic succession: at the base is quartz- pebble gravel with a matrix of sandy clay; overlying the basal gravel, or resting on weathered bedrock where gravel is absent, is dense gray clay through which are scattered quartz pebbles and fragments of carbonized wood. Locally the clay is very carbonaceous and grades into peat or muck. Generally above the clay is gray, bufi', or brown coarse to fine sand over- lain by bufi', brown, or gray clayey silt. The upper— most sediment is red to brown sandy silt. It is the most widespread of the flood-plain sediments. At places the red to brown sandy silt rests directly on the dense gray clay, and where it does the top surface of the clay may be channelled, scoured, and pitted. The sequence of fluvial sediments averages 14.6 feet in 208 thickness and is composed of 1.5 feet of gravel, 3.6 feet of clay, and 9.5 feet of sand and silt. The sediments are Recent in age, but small areas of pre-Wisconsin muck, clay, and gravel are present in the heads of some streams. Red to brown sandy silt in the upper part of the sequence has been deposited since the region was cleared for farming in the nineteenth century. Flood plains in the western Piedmont are rarely more than 2 or 3 miles long or more than 2,500 feet wide (Overstreet, Theobald, and Whitlow, 1959, p. 712). They range in area from several thousand to 7 million square yards. About half of the flood plains are 200—800 feet wide and more than 1 million square yards in area. Small flood plains at the extreme heads of the creeks, which were the sites of fermer placer mining, are about a few hundred to 200,000 square yards in area, and the smallest of these contain but a few hundred to a few thousand cubic yards of monazite- bearing sediment. The average volume of sediment in individual downstream flood plains is 7 million cubic yards, and the largest continuous monazite-bearing flood plain in North Carolina, along the South Fork Catawba River in Catawba County and Lincoln County, contains about 60 million cubic yards of sediment. Tenors of the fluvial deposits range from less than 0.1 pound of monazite per cubic yard to more than 50 pounds per cubic yard and average about 0.8 pound per cubic yard. In 84 flood plains classed as placers in the Piedmont of North and South Carolina the average tenor in monazite for the sequence of sedi- ments was estimated to be 1.3 pounds per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 712). The greatest tenors are in coarse-grained basal gravel, and the least tenors are in silt and clay. Tenors decrease downstream from large values at the heads of creeks and branches to small values in the lower reaches of large tributaries in the monazite belt or parts of trunk streams in and immediately downstream from the belt. Gravel such as that mined in the heads of creeks was reported by Mertie (1953, p. 10) to average 8.4 pounds of monazite per cubic yard at 52 localities sampled in North and South Carolina. The average tenor of headwater sediments taken from grass roots to bedrock at many hundreds of localities in these two States was estimated by Overstreet, Theo- bald, and Whitlow (1959, p. 714) to be about 4 pounds of monazite per cubic yard. Extreme examples of local concentration mentioned in the literature show that mined gravel can contain as much as 30 percent of monazite (Graton, 1906, p. 117), but mostly the gravel contains less than 1 percent of monazite, gener- ally 0.25 percent or less (Nitze, 1897, p. 129; Bohm, THE GEOLOGIC OCCURRENCE OF MONAZITE 1906; Ladoo, 1925, p. 396; McDaniel, 1943, unnum- bered p.; Houk, 1946, p. 8). The resources in monazite in fluviatile placers along tributaries to the Broad River and southern tributaries to the Catawba River in Cleveland, Rutherford, Polk, McDowell, Burke, Catawba, and Lincoln Counties, N.C., were estimated in 1959 to be at least 490,000 short tons (Overstreet, Theobald, and Whitlow, 1959, p. 713). Resources of monazite in placers in the western monazite belt to the northeast of the Catawba River and southwest of the Yadkin River, N.C., have not been evaluated, but they are probably on the order of one-third as large as the resources southwest of the Catawba River. An appraisal of the area between the Yadkin River and the North Carolina State line at Virginia indicates significant resources of monazite are not present (A. M. White, written commun., 1954). No appraisal of monazite resources in fluviatile placers in the eastern monazite belt of Mertie (1953, pl. 1) has been made. The writer thinks that fluviatile placers in the eastern belt will prove to have a lower average tenor than stream placers in the western belt. Possibly the average amount of thorium oxide in detrital mona- zite in the eastern belt is less than in the western belt. Significant deposits of detrital monazite may not exist in the Piedmont between the two belts. This estimate should be strongly qualified by pointing out the pos- sibility of placers associated with local masses of monazite-bearing granite like the one found by Henry Bell, 3d (oral commun., 1963) in eastern Mecklenburg County or by pointing out the possibility of fossil or modern placers related to relicts of alluvium left along former drainage ways (White and Stromquist, 1961). STOKES COUNTY AND SURRY COUNTY Streams tributary to the Dan and Yadkin Rivers in parts of Stokes and Surry Counties, NC, in the western monazite belt of Mertie (1953, pl. 1) were investigated in 1952 for pessible deposits of detrital monazite by A. M. White and G. A. Miller of the US. Geological Survey (A. M. White, written commun., 1954). Small amounts of monazite were observed at several localities, but placers suitable for mining were not found. The area is underlain by staurolite- and epidote— bearing mica schists intruded locally by granite. Pegmatite is not as widespread in these schists as it is in the sillimanitic core of the belt exposed to the south— west of the Yadkin River (Overstreet and Griflitts, 1955, pl. 1), and Inigmatitic rocks are absent. Out of 126 concentrates from sediments in streams draining an area of 600 square miles in the two counties, only 17 contained more than a trace of monazite. Ilmenite was the most abundant mineral in most of the concen- NORTH CAROLINA trates, and variable amounts of staurolite, epidote, magnetite, and garnet were present. The mineralogi- cal composition of the 17 concentrates with more than a trace of monazite is shown in table 69. Out of 15 concentrates, 5 are from F aggs Creek, North Double Creek, Big Creek, and other tributaries to the Dan River in Stokes County, and 12 out of 111 concentrates are from tributaries to the Ararat River, Fisher River, and Mitchell River in Surry County. Estimates indi- cated only two localities where the tenor of the sedi- ments exceeded 1 pound of monazite per cubic yard. The maximum estimated tenor was 1.8 pounds of monazite per cubic yard found for riffle grave] in Faggs Creek at a point about 3 miles northwest of Danbury, Stokes County (table 70). Even if the tenors of the sediments had been con- siderably greater, the streams are not well suited for monazite mining. Flood plains in the sampled parts of Stokes County and Surry County are small and dis- continuous. In general the best—developed flood plains tend to be along the upstream parts of the large creeks, but the alluvium is shallow, averaging only 10.5 feet in thickness except on the main rivers where the average thickness reaches about 21 feet. The large TABLE 69.—Mineralogical composition, 209 flood plains are outside the areas of monazite-bearing bedrock, and their sediments contain no monazite or only a trace. No flood plain in this area is a monazite placer. WILKES, IREDELL, ALEXANDER, CALDWELL, AND CATAWBA COUNTIES Late in the history of monazite placer mining in North Carolina, about 1906, monazite was discovered by D. B. Sterrett in Cub Creek near Wilkesboro in Wilkes County (Pratt, 1907b, p. 109; Pratt and Sterrett, 1908a, p. 315; Bryson, 1937, p. 131). At the time it was found the occurrence was described as having only a limited extent, and the percentage of monazite in the concentrates was said to be small; nevertheless, the locality is the northeasternmost placer discovered during the life of the monazite industry in the Carolinas. Placers in Wilkes County have received no further attention. The year 1906 also saw the extension of known placer deposits into northern Iredell County. Some monazite was even produced in the county during that year and also from 1915 through 1917, but available records do not identify the mining district except to say that it was north of Statesville (Pratt, 1907b, p. in weight percent, 0f managing-bearing concentrates from alluvium in Stokes and Surry Counties, [Analystsz Jerome Stone, M. N. Girhard, H. B. Groom, Jr., C. J. Spengler, and R. P. Marquis, U.S. Geol. Survey, in 1953. Symbols used: Tr., trace, _., absent] 110268 110230 110231 110224 110223 110220 110218 110219 110216 110213 110214 110211 110210 110208 98805 98806 98780 Weight of concentrate._grams._ 115. 7 77. 9 39. 0 49. 7 87. 3 26. 0 54. 6 71. 8 20. 6 112. 4 104. 0 144. 2 26. 3 25. 0 49. 0 19. 5 22. 8 Magnetite ..................... 6 4 l6 3 3 3 18 5 3 3 5 2 3 3 1 Tr. 7 llmenite ............... . 60 60 52 78 83 60 71 68 73 85 72 72 81 64 45 88 39 Quartz ................. . 13 5 15 5 7 16 7 5 15 4 10 13 5 21 15 8 24 Monazite .............. . 8 2 2 11 4 12 2 2 1 1 2 2 1 4 4 3 l Garnet ................. . 11 9 6 1 2 2 Tr. 3 4 2 6 5 7 1 .. _- Tr. Zircon ........... _ Tr. 2 3 Tr. Tr. 1 2 Tr. 2 1 2 Tr. Tr. 1 __ Tr. 1 Silllmanite .. 2 Tr. __ __ __ _ _ 2 Tr. Tr Tr. Tr. Tr. -_ __ ._ 3 Staurolite.. ._ 4 Tr. 1 Tr. 6 Tr l4 1 3 Tr. 6 3 4 ._ 2 Amphibole 1 1 Tr. Tr. Tr. -_ Tr Tr. Tr. Tr. Tr. Tr. _. ._ __ __ 2 Tourmaline Tr. Tr. __ Tr. __ Tr. Tr. 1 Tr. Tr. __ Tr. __ 1 __ __ __ Epidote ........ __ _. 9 6 1 1 Tr. Tr Tr. Tr. l 1 .. Tr. 1 Tr. 1 21 Other minerals _________________ 11 1 2 l Tr. 2 Tr, 3 Tr, .. __ 1 Tr. 3 Tr. .. 12 ._ __ __ .. _. ._ l Rutile. 2 Xenotime. 3 Kyanite. . Stokes County: urry County: Surry County—Continued 110268 Faggs Creek. 110218, 110219, 110208. Stoney Creek. 110230,110231.' North Double Creek. 110224.110223. Big Creek. 110216.110220. Big Creek. 110213,110214. Toms Creek. 110211, 110210. Flat Shoal Creek. 98805, 98806. Stewarts Creek. 98780. Fisher River. TABLE 7 0.—Estimated tenor, in pounds per cubic yard, of monazite-bearing sediments in Stokes and Surry Counties, N .C. [A. M. White (written commun., 1954)] Stokes County Surry County Faggs North Big Creek Toms Creek Flat Stony Stewarts Fisher Creek Double Creek Shoal Creek Creek Creek River 110268 110230 110231 110224 110223 110220 110218 110219 110216 110213 110214 110211 110210 110208 98805 98806 98780 Monazite ________________ 1.8 0.3 0.2 1 1 0.7 0.6 0.2 0.3 0.04 0.2 . 9.3 4.0 7 7 14.5 3.1 7.7 9.7 3.0 19.1 .3 . 2 ________________ 05 . 2 ........ . 08 . 2 1. 4 .5 1 3 1 ........ .4 .2 .4 Other minerals ........... (2) ________________________________________ (3) (4) ........ ' Sillimanite, 0.3. 1 Rutile, 0.2. ‘ Kyanite, 0.04. 2 Rutile, 0.3; sillimanite, 0.3. 5 Rutile, 0.4. 6 Sillimauite, 0.1. 210 109, 122; Sterrett, 1908b, p. 274; Pratt and Berry, 1919, p. 104—105; Drane and Stuckey, 1925, p. 19; Bryson, 1927, p. 15—16). Pratt’s map of 1916 indicates the placers could have been anywhere in the north- western part of Iredell County to the north, northwest, and northeast of Statesville (Pratt, 1916, pl. 1). As early as 1880 monazite was known in veins, schist, and gold placers at Milhollands Mill on Third Creek about 2.6 miles S. 30° E. from Hiddenite in Alexander County (Genth and Kerr, 1881, p. 84, 91; Dana, E. S., 1882, p. 247; Bath, 1886, p. 149—150; Eng. and Mining Jour., 1888, p. 2; Genth, 1891, p. 77—78, 86; Mertie, 1953, p. 8), but the placers seem not to have attracted commercial attention until about 1906. In 1907 the county was listed as one of the monazite-producing areas in North Carolina (Pratt, 1908, p. 61). The locations of the mined monazite placers have not been given in the literature. Most of the county is within the monazite-bearing area outlined by Pratt (1916, pl. 1), but the common references to monazite in the region around Hiddenite and Stony Point suggest that the eastern part of the county may have been the main source. Detrital mona— zite from Third Creek at the original site of Milhol- lands Mill was said by Mertie (1953, p. 12) to contain 5.19 percent of ThOz and 0.36 percent of U308. Monazite placers were discovered in Caldwell County between 1898 and 1908, but they do not seem to have been mined and details as to location have not been published (Pratt, 1907b, p. 109; Sterrett, 1908b, p. 274). Probably the placers are in the eastern and southeastern parts of the county. Catawba County was known as early as 1893 to possess monazite placers. The western part of the county and the drainage basins of Henry Fork and Jacob Fork were the most often cited localities in the early literature (Mezger, 1895, p. 822; Nitze, 1895c; Pratt, 1903, p. 181; Béhm, 1906; Pratt, 1907b, p. 109; Sterrett, 1908b, p. 274). Other than to indicate these general areas and to show that monazite was shipped from the county during 1906 and 1907, the early reports contribute little to a knowledge of monazite in the county. During 1952 A. M. White of the IU.S. Geological Survey studied the distribution of detrital monazite throughout the county. Results of his in- vestigations showed that monazite is present in the western and eastern parts of the county and locally in the central part, that rutile, sillimanite, and al- mandine commonly accompany detrital monazite in western Catawba County but not in the central and eastern areas, and that four main drainage basins contain monazite (Overstreet and Griflitts, 1955, pl. 1; THE GEOLOGIC OCCURRENCE OF MONAZITE Overstreet, Cuppels, and White, 1956; Overstreet, Theobald, and Whitlow, 1959; Overstreet, 1962, figs. 1,2). The southeast edge of the core of the monazite belt passes northeastward across the western part of Catawba County (A. M. White, written commun., 1954). In this area, which is about 8—12 miles wide, monazite makes up 5—20 percent of the heavy minerals in concentrates from alluvium. The flank of the monazite belt is very narrow adjacent to the core in the southwestern part of the county, but about 4 miles north of Newton a great eastward expansion occurs, and a zone in which concentrates from stream sedi- ments have 1—5 percent of monazite extends eastward to the Catawba River and thence southward across Catawba County and Lincoln County (Overstreet, 1962, fig. 2). A small outlying area of monazite- bearing alluvium occurs at Newton and extends south- eastward nearly to the border with Lincoln County. Rutile and sillimanite are minor accessory minerals, and garnet and ilmenite are major accessory minerals in monazite-bearing concentrates from the south- western part of the county and the outlying area at and southeast of Newton. The occurrences are in parts of broad and persistent bands of these minerals which are found in the core of the monazite belt from the Catawba River southwestward into South Carolina. Small amounts of rutile and garnet are present in monazite-bearing concentrates from the flank of the belt in the eastern part of the county, and ilmenite is common there, but sillimanite is only sporadically present. Concentrates from eastern Catawba County are rich in epidote and staurolite, and staurolite is locally present at the extreme edge of the core of the belt in the southwest corner of the county. Magnetite is generally absent from concentrates from the core of the belt in the western part of the county, but it makes up as much as 40 percent of some concentrates from the monazite-bearing area at and southeast of Newton. Magnetite in abundances up to 20 percent of the concentrate is present in eastern Catawba County on the flank of the monazite belt. It becomes increasingly abundant southward into Lincoln County. The main monazite—bearing streams in Catawba County are Lyle Creek, Clark Creek, the downstream part of Henry Fork, and Jacob Fork. Their com- bined resources in detrital monazite were estimated by White to be about 49,000 short tons (Overstreet, Theobald, and Whitlow, 1959, p. 711). NORTH CAROLINA Lyle Creek and adjacent streams are tributary to the Catawba River in northeastern Catawba County. Their basins are underlain by deeply weathered biotite schist, biotite gneiss, sillimanite schist, and hornblende gneiss, all of which are more or less injected by pegma- tite (A. M. White, written commun., 1954). Staurolite— bearing rocks are prominent east and south of the mouth of Lyle Creek but are scarce in the basin. Lyle Creek and adjacent streams are on the southeast flank of the monazite belt. Flood plains along the downstream half of Lyle Creek are discontinuous and wide compared to their lengths, and they attain widths as great as 2,200 feet. Along the upstream half of Lyle Creek the flood plains were reported to average about 400 feet in width (A. M. White, written commun., 1954). Sand and silt was estimated by White to make up about 75 percent of the sediment, clay about 16 percent, and gravel 9 percent. Because of the large proportion of fine-grained sediment in the flood plains and the loca- tion of Lyle Creek and adjacent streams on the flank of the monazite belt, the average tenor of the flood- plain sediments was estimated by White to be only 0.4 pound of monazite per cubic yard and the resources some 11,300 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 711) . Clark Creek and other tributaries to the South Fork Catawba River drain the area of monazite-bearing rocks in central Catawba County from the vicinity of Newton southeastward nearly to Lincoln County. Clark Creek flows southward out of these monazite— bearing rocks into a monazite-free part of central Lincoln County and empties into the South Fork Catawba River on the west side of Lincolnton (Over— street, 1962, fig. 1). Streams in only about half of the drainage basin contain monazite—bearing alluvium. Resources in monazite for the basin were estimated by A. M. White to be about 11,000 short tons in alluvium, the average tenor being 0.4 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). The downstream part of Henry Fork is the stretch of river between Queens Creek in Burke County and the confluence of Henry Fork with Jacob Fork in Catawba County. The junction of the two rivers forms the South Fork Catawba River. Biotite gneiss, biotite schist, and sillimanite schist are the prinicpal kinds of rocks in the downstream part of Henry Fork. Pegmatite is locally abundant (A. M. White, written commun., 1954). This part of the basin of Henry Fork is in the center and on the southeast side of the core of the monazite belt. Concentrates from alluvium 211 near the head of Queens Creek contain from 40 to 50 percent of monazite. This percentage declines east- ward to the border between Burke County and Catawba County where concentrates contain 20 percent of monazite. From this point to the confluence of Henry Fork and Jacob Fork, concentrates contain from 10 to 20 percent of monazite. Rutile is absent from Queens Creek to the Catawba County line but is present in concentrates from this boundary to the mouth of Henry Fork. Sillimanite makes up from 1 to 5 percent of the concentrate, and garnet constitutes from 5 to 20 percent of the heavy-mineral suite. Il- menite is common. Epidote and staurolite are vir- tually absent. Magnetite is absent or scarce through the western part of the basin but appears toward the east and makes up 1—30 percent of the concentrate. Magnetite reaches its greatest abundance in alluvium from creeks near the confluence of Henry Fork and Jacob Fork at the flank of the belt. Flood-plain sediments range in thickness from about 7 feet along small creeks to about 18 feet in parts of the valley of Henry Fork, but only about 10 percent of the sediment is gravel. The average tenor of the sediments was estimated by A. M. White to be 1.0 pound of monazite per cubic yard, and the resources in monazite were estimated to be at least 13,700 short tons (Overstreet, Theobald, and Whitlow, 1959, p. 711). Some tributaries to Henry Fork in Burke County were formerly mined for monazite, but specific locali- ties have not been given in the literature (Nitze, 1895c; Pratt, 1903, p. 181; Bohm, 1906). Jacob Fork drains parts of Burke, Catawba, Cleve— land, and Lincoln Counties immediately south of the basin of Henry Fork. Jacob Fork rises in the South Mountains in Burke County and flows eastward across biotite schist, biotite gneiss, and sillimanite schist at the core of the monazite belt to its junction with Henry Fork in Catawba County on the southeast flank of the belt. Parts of the stream and its tributaries in Burke, Catawba, and Lincoln Counties were said to have been mined for monazite, but individual placer de- posits were not described (Nitze, 1895c; Pratt, 1903, p. 181; Bohm, 1906). Concentrates from alluvium at the headwaters and mouth of Jacob Fork were found by A. M. White (written c0mmun., 1954) to have only a few percent of monazite, but concentrates from streams in the cen- tral part of the basin were found to contain 30—60 percent of monazite. Gravel from streams in the basin was estimated by White to contain as much as 16.9 pounds of monazite per cubic yard, but most samples of 212 gravel had less than 5 pounds of monazite per cubic yard: Tenor of gravel (lb per cu ft) Monazite ______________________________ 0 . 08—16 .9 Ilmenite _______________________________ .6 -38.8 Rutile _________________________________ 0 — 1.1 Zircon _________________________________ 0 — 2.1 Garnet ________________________________ .1 — 8.5 Kyanite _______________________________ 0 — .7 Sillimanite _____________________________ 0 - 1.4 The tenor of gravel in a probable former placer along Camp Creek, a southern tributary to Jacob Fork in Cleveland County and southeastern Burke County, was estimated by Mertie (1953, p. 8, 10) to be 7.1 pounds of monazite per cubic yard. Analysis of this monazite disclosed 6.20 percent of Th02 and 0.45 percent of U308 (Mertie, 1953, p. 12). Rutile in low percentages occurs in about half of the concentrates from the basin of Jacob Fork. Sil- limanite, commonly present in amounts of as much as 5 percent of the concentrate, locally reaches 10 percent. In the northwestern part of the basin it is absent. Most concentrates contain 15—20 percent of garnet and 50—70 percent of ilmenite. Staurolite is common in concentrates from streams entering Jacob Fork from the line between Burke County and Cat- awba County to a point about 6 miles upstream from Henry Fork, but epidote is virtually absent. Mag- netite is common in concentrates from the lower end of Jacob Fork (Overstreet and Griffitts, 1955, pl. 1). Resources in monazite in the basin of Jacob Fork were estimated by A. M. White to be about 13,200 short tons in alluvim, the average tenor being 0.8 pound of monazite per cubic yard (Overstreet, Theo- bald, and Whitlow, 1959, p. 711). BURKE COUNTY AND MCDOWELL COUNTY Detrital monazite was reported from gold placers in Burke County and McDowell County in 1871 by F. A. Genth. W. E. Hidden found it to be a common accessory mineral in concentrates from placers in these counties, and in 1880 he shipped 50 pounds of detrital monazite from the Brindletown gold placer district on Silver Creek in Burke County (Genth and Kerr, 1881, p. 84). Systematic recovery of placer monazite in Burke County was not undertaken until 6 years later, although monazite concentrates from the county were described (Mallet, 1882, p. 205; Dana, E. S., 1882, p. 248; Penfield, 1882, p. 251; Am. Naturalist, 1883, p. 313; Dana, E. S., 1884, p. 542). In 1887 the Brindletown district was the source of the first real output of monazite, 12 short tons, produced in North Carolina, and thereafter production was maintained through 1910 with sporadic mining through 1917 THE GEOLOGIC OCCURRENCE OF MONAZITE (table 30). It is not known when placers were first opened for monazite in McDowell County, but it was probably almost at the same time sustained production began in Burke County, because as early as 1888 deposits in McDowell County were said to have ex- ploitable monazite sand (Eng. and Mining Jour., 1888, p. 2). Mining apparently began in McDowell County around Dysortville and Demming in the head- waters of Muddy Creek in the next drainage basin to the west of the Silver Creek basin (Dennis, 1898, p. 494; Pratt, 1901, p. 31; Zodac, 1958). In 1898 an act was passed by the Legislature of North Carolina to prohibit mining in Muddy Creek (Pratt, 1901, p. 31). Between that date and 1900 monazite was not mined in the county, but from 1901 through 1906 McDowell County was again a source of monazite (table 58), but the mining localities are not known. In 1902 tributaries to Muddy Creek known as Long Branch, Alexander Branch, and MacLawrath Branch were cited as sources of placer monazite (Pratt, 1902, p. 60), but it is not clear whether these creeks were mined before or after the act of 1898. The total output of placer monazite in Burke County and Mc- Dowell County is not known, but it may have been as much as one-third of the total production in North Carolina. Monazite-bearing concentrates from gold placers at the heads of Silver Creek and Muddy Creek between Brindletown in Burke County and Dysortville in Mc- Dowell County were commonly cited as sources for rare minerals in North Carolina (Genth, 1891, p. 77—78, 86; Pardee and Park, 1948, p. 65). In 1895 the number of minerals identified in concentrates from gold sands near Brindletown was said to be immense (Becker, 1895, p. 291), and in 1896 a list was published showing 103 varieties of minerals in placers at Dysort- ville (Eng. and Mining J our., 1896) . After the monazite industry closed in North Car- olina in 1917, the placers in Burke County and Mc- Dowell County received no geologic attention until 1943, when W. T. McDaniel of the Tennessee Valley Authority examined several deposits in Burke County (McDaniel, 1943; Lefl'orge and others, 1944), and 1945, when J. B. Mertie, Jr., of the US. Geological Survey sampled placers in both counties (Mertie, 1953, p. 8—12). Systematic study of the placers was not undertaken until 1952, when A. M. White of the US. Geological Survey sampled and drilled monazite- bearing streambeds in Burke County and McDowell County (Overstreet, Cuppels, and White, 1956; Over- street, Theobald, and Whitlow, 1959). The results of White’s work showed that all streams in Burke County are monazite bearing and that most NORTH CAROLINA streams in the eastern part of McDowell County con— tain monazite (A. M. White, written commun., 1954). Burke County from a point 4 miles east of Morganton is in the core of the monazite belt. Concentrates from alluvium in this area contain from 10 to 30 percent of monazite and locally contain as much as 60 per- cent (the previously described Jacob Fork area in southeastern Burke County). The western part of Burke County and eastern McDowell County nearly as far west as Marion are in the northwest flank of the monazite belt. Most concentrates from alluvium in this area have 1—5 percent of monazite, and some lack monazite. A zone at the head of South Muddy Creek in McDowell County has alluvium in which concentrates contain 5—20 percent of monazite. This zone extends northeastward into the drainage basin of Silver Creek in Burke County. This rather small zone on the flank of the belt includes most of the famous placer localities in the area around Dysort- ville and Brindletown (Overstreet, 1962, fig. 2). Rutile is an uncommon accessory mineral in con- centrates except in southeastern and northeastern Burke County. Sillimanite is a nearly constant ac- cessory mineral in amounts between 1 and 5 percent of the concentrate in the core of the belt through Burke County east of Morganton. Locally Sillimanite makes up as much as 20 percent of the concentrate in northeastern Burke County. On the flank of the belt, including the monazite-rich area at the heads of South Muddy Creek and Silver Creek, only traces of sil- limanite are present. Northwest of the monazite belt in the area around Marion, McDowell County, kyanite is a common component of concentrates. In the mona- zite-bearing part of McDowell County and throughout Burke County, garnet commonly makes up more than 5 percent of the concentrate. In the core of the belt in Burke County east of Morganton, garnet usually is present in amounts between 15 and 40 percent of the concentrate, but on the flank of the belt it seldom exceeds 10 percent of the concentrate. Ilmenite is much more abundant in the core of the monazite belt in the eastern part of Burke County than on the northwest flank of the belt in the western part of Burke County and the eastern part of McDowell County. Commonly concentrates contain 50—70 per- cent of ilmenite in the core and 10—30 percent on the flank of the belt. Concentrates from the north- west flank of the belt are likely to have 1—25 percent of epidote and 5—70 percent of magnetite, whereas those from the core of the belt in Burke County contain no epidote and less than 5 percent of mag- netite. Many concentrates are free of magnetite (Overstreet and Griflitts, 1955, p. 556). 213 The resources in monazite in Burke County were appraised by A. M. White in five clusters of streams of which two, the downstream par-t of Henry Fork and the basin of Jacob Fork, extend into Catawba County and were reviewed in the section “Wilkes, Iredell, Alexander, Caldwell, and Catawba Counties.” The three other clusters of streams are Hunting Creek and six short tributaries to the Catawba River, Laurel Creek and other headwater tributaries to Henry Fork, and Silver Creek. Monazite-bearing streams in McDowell County include north-flowing creeks which enter the Catawba River and south- flowing streams which are tributary to the Second Broad River. Only those streams emptying into the Catawba River are discussed here, because the south- flowing Second Broad River drainage is more appro- priately described in the section on Rutherford County, which follows. Muddy Creek discharges into the Catawba River and drains most of the monazite- bearing parts of McDowell County. Resources in the three streams in Burke County and the Muddy Creek basin in McDowell County were estimated by A. M. White to be at least 43,000 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 711). Hunting Creek and six other small streams rise in the South Mountains and flow northward into the Catawba River between Morganton in Burke County and the Burke—Catawba County line to the east. The westernmost of these small streams, Hunting Creek, is on the northwest flank of the monazite belt, but the other streams are in the core of the belt (A. M. White, written commun., 1954). From west to east the percentage of monazite increases in concentrates from alluvium. Concentrates from Hunting Creek commonly have from 1 to 5 percent of monazite; in the extreme southeast branches of Hunting Creek, concentrates have as much as 20 percent of monazite. From 5 to 10 percent of monazite is in concentrates from Double Creek, the next stream to the east, and eastward in McGalliard Creek the abundance rises to 20 percent or more. In the most easterly part of the area, around Drowning Creek, the concentrates contain as much as 30 percent of monazite. Flood plains on these streams are small and dis- continuous; only Hunting Creek has flood plains along most of its length. Most of the flood-plain sediments are about 8—12 feet thick. The weighted—average tenor of the sediments was estimated by White to be 0.7 pound of monazite per cubic yard, and the resources were estimated to be about 5,600 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 711). Despite the low average tenor of the alluvium, most of the monazite is along Hunting Creek because it has 214 about 75 percent of the total volume of alluvium in the area (A. M. White, written commun., 1954): Average tenor (lb of monazite Resources per cu yd) (short tons) Hunting Creek ________________________ 0.7 3, 500 Double Creek _________________________ .8 160 Hoyle Creek __________________________ .9 470 Island Creek __________________________ 1.6 70 Drowning Creek _______________________ 2.3 750 Others ________________________________________ 650 Total ___________________________________ 5, 600 Laurel Creek and other headwater tributaries to Henry Fork in Burke County were estimated by A. M. White to contain about 2,300 short tons of monazite in alluvium with an average tenor of 0.6 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). The area drained by these streams is underlain by biotite gneiss, biotite schist, and sillimanite schist in a monazite—poor reentrant of the flank of the belt on the northwest side of the core. Flood plains are small and discontinuous. Despite local high-tenor gravel in riflies along small streams, the tenor and resources of individual streams are small. A repre- centative sample containing 7 pounds of monazite per subic yard was panned by Mertie (1953, p. 8, 10) from Rock Creek at a locality seven-eighths of a mile east— northeast of Pleasant Grove Church. According to A. M. White (written commun., 1954) flood-plain sedi. ments in Rock Creek contain the highest average tenor: Average tenor Resource» (lb ofmonazite (short ' per cu yd) tons) Headwaters of Henry Fork ______________ Trace Trace Henry Fork near Enola _________________ 0. 9 550 Henry Fork from Dafty Creek to Ben Branch _____________________________ . 4 500 Rock Creek ___________________________ 1. 7 380 Laurel Creek __________________________ . 3 18 Henry Fork between Laurel Creek and Cub Creek __________________________ . 9 850 Total ___________________________________ 2, 298 Detrital monazite from Rock Creek was reported by Mertie (1953, p. 12) to contain 4.94 percent of T1102 and 0.58 percent of U303. Silver Creek rises in the South Mountains in the southwestern part of Burke County and flows toward the north and northeast to empty into the Catawba River about a mile west of Morganton. The basin of Silver Creek is underlain by biotite schist, biotite gneiss, hornblende gneiss, granitic rocks, and sparse sillimanite schist on the northwest flank of the mona- zite belt (A. M. White, written commun., 1954) . Con- centrates from alluvium in the easternmost branches of the creek and in the downstream parts of the other branches generally contain 5 percent of monazite or THE GEOLOGIC OCCURRENCE OF MONAZITE less, but in the upper reaches of the western branches, particularly in the Brindletown area, concentrates commonly contain 20 percent of monazite. Even in the lower parts of the stream, local fairly rich occur- rences of monazite can be found in riffle gravel along small tributaries. A sample of riifle gravel from a locality 2.5 miles south of Glen Alpine was reported by Mertie (1953, p. 8, 10) to contain 4 pounds of monazite per cubic yard. As was previously stated, detrital monazite has long been known in the Silver Creek basin, and gold placers in the Brindletown area were the earliest commercial source for monazite in the United States. The Mills mine (Genth and Kerr, 1881, p. 84), the White Bank gold mine on the lower slope of Pilot Mountain west of Brindle Creek, Hall Creek, and the Linebacher place (Pratt, 1902, p. 60) were frequently mentioned as having been mined for monazite. The placers are regarded as having been mined out for gold by 1905 (Pardee and Park, 1948, pl. 14) . Possibly the reason the head of Silver Creek in the Brindletown area was better known as a monazite placer area than downstream parts of the basin is because concentrates from the Brindletown area con- tain less magnetite and epidote than concentrates from other parts of the basin. Magnetite reaches 70 or 80 percent of the concentrate locally in tributaries to Silver Creek below the mouth of Hall Creek and in parts of eastern tributaries like Double Branch (A. M. White, written commun., 1954). Concentrates from Hall Creek and the headwaters of Bailey Fork are relatively free from epidote, but concentrates from the rest of the basin contain as much as 30 percent of epidote. Flood plains are commonly long and continuous on Silver Creek and its tributaries, and this pattern is maintained far up toward the headwaters of the north- flowing tributaries. Short reaches along the central part of Silver Creek, Clear Creek, and Bailey Fork lack flood plains. The widest flood plains begin near the mouth of Clear Creek and extend downstream along Silver Creek to a point about a mile upstream from the Catawba River. In this part of the valley the sediments are 17—21 feet thick, and near the head of Hall Creek they are 12 feet thick. Gravel decreases in abundance downstream from 25 to 40 percent of the sediment near the heads of the streams to 5—10 percent near the mouth of Silver Creek. An appraisal by A. M. White of the resources of monazite in the basin of Silver Creek revealed at least 16,500 short tons of monazite in alluvium that has an average tenor of 0.8 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, NORTH CAROLINA p. 711). These resources were principally in the great flood plain along Clear Creek and Silver Creek down- stream from the mouth of Clear Creek (A. M. White, written commun., 1954) : Average tenor Resources (lb o/monazite (short per cu yd) tone) Brindle Creek, Silver Creek, and Hall Creek to mouth of Hall Creek _________ 0. 7 1, 800 Silver Creek between Hall Creek and Clear Creek _______________________________ . 6 2, 250 Sutterwhite Creek, upper part of Clear Creek, and Double Branch ____________ 1. 7 3, 150 Lower part of Clear Creek, Silver Creek to a point 1.25 miles upstream from Bailey Fork _______________________________ l. 0 6, 000 Silver Creek from point 1.25 miles up- stream from Bailey Fork to Catawba River ______________________________ . 4 1, 950 Bailey Fork ___________________________ 1. 1 1, 350 Total ___________________________________ 16, 500 Two areas in the basin of Silver Creek and one on a nearby part of the Catawba River were explored by the US. Bureau of Mines in 1952. During February two churn-drill holes were sunk near the upstream end of the main flood plain on Hall Creek, and one hole was drilled near the mouth of Hall Creek upstream from the Silver Creek valley (R. F. Griflith, written commun., 1952). In October four holes were drilled in the flood plain along Silver Creek at the mouth of Clear Creek, and three holes were sunk in a large flood plain on the Catawba River near Morganton (Hansen and White, 1954, p. 4—5). Results of the drilling on Hall Creek showed that the alluvium is 8—17 feet thick and that it contains 25—38 pounds of black sand per cubic yard, of which 0.84—1.39 pounds per cubic yard is monazite, and a little gold. Results of drilling in the valley of Silver Creek at the mouth of Clear Creek showed that the alluvium contained 12 pounds of black sand having 0.83 pound of monazite and about 4 cents worth of gold per cubic yard. A downstream decrease in the tenor in mona- zite was indicated. The tenor dropped progressively to 0.6 pound and 0.4 pound per cubic yard at the lower end of Silver Creek (Hansen and White, 1954, p. 5, 22—23). A mineralogical analysis of a composite con- centrate from sediment from the four drill holes dis- closed 18 percent of epidote and 6.2 percent of mona- zite (Hansen and White, 1954, p. 15) : Percent Percent Epidote ________________ 18 Monazite _____________ 6. 2 Ilmenite _______________ 32 Rutile _______________ 2 Quartz _________________ 11 Sillimanite and kyanite- 4 Garnet _________________ 13 Xenotime ____________ . 6 Hornblende _____________ 5 Magnetite ______________ 1 Total __________ 98. 8 Zircon _________________ 6 215 Less than 1 percent each of pyrite, spinel, tourmaline, muscovite," and radioactive opaque minerals were pre- sent in the composite concentrate. Reserves in this part of Silver Creek were estimated to be 6,250 short tons of monazite, 38,500 short tons of ilmenite, 15,800 short tons of garnet, and 6,800 short tons of zircon (Hansen and White, 1954, p. 24). Monazite sand from the Brindletown district was hand picked by Penfield (1882, p. 251—252) to provide a clean separate for analysis. Penfield carefully chose only the large monazite grains having a cinnamon- brown color, thereby practically insuring that the de- trital grains he analyzed were derived from pegma- tite because the monazite from the schists and gneiss tends to be fine-grained and yellow. This brown monazite was found to have a specific gravity of 5.10 and an average of 6.49 percent of thorium oxide (Pen- field, 1882, p. 252; Johnstone, 1914, p. 58; Imp. Inst. [London], 1914a, p. 60). Chemical analyses, in percent, of monazite from the Brindletown district 1 2 3 Mean 03.0, ____________________ 31. 38 31. 94 30. 77 31. 38 (La, Di)203 _______________ 30. 67 30. 80 31. 17 30. 88 Th0; ____________________ 6. 68 6. 24 6. 56 6. 49 P205 _____________________ 29. 45 29. 20 29. 20 29. 28 SiO, _____________________ 1. 40 ________________ 1. 40 Loss on ignition ___________ . 20 . 20 ________ . 20 Total ______________ 99. 78 98. 38 97. 70 99. 63 The highest grade of monazite sand from the Brin- dletown area of Silver Creek was said by Nitze (18950) to contain 4.00—6.60 percent of T1102, whereas commercial concentrates from the same area were re- ported by Pratt (1902, p. 60) to contain 2.18—6.54 percent of Th02. Monazite sand from an unknown locality in Burke County was reported to contain 7.28 percent of Th02 (Pratt, 1903, p. 182). Schaller (1922, p. 15) stated that monazite from Brindletown was analyzed by W. F. Hillebrand of the US. Geological Survey and found to contain 4.3 percent of Th0;;. Detrital monazite from a southern tributary to Silver Creek 21/2 miles south of Glen Alpine was reported by Mertie (1953, p. 12) to have 2.48 percent of Th02 and 0.28 percent of U303. Monazite from the Silver Creek flood plain near the mouth of Clear Creek was anal- yzed by the US. Bureau of Mines and shown to have 4.8 percent of ThOz and 0.44 percent of U308 (Han— sen and White, 1954, p. 21) . Muddy Creek rises in southeastern McDowell County and flows north to its junction with the Cat- awba River in Burke County. It has two main forks 216 known as South Muddy Creek and North Muddy Creek which join about 1.4 miles from the Catawba River. The basins of these streams are underlain by biotite gneiss, hornblende gneiss, biotite schist, granite, pegmatite, and scarce sillimanite- and kyanite-bearing schists. Muddy Creek and its tributaries are on the northwest flank of the monazite belt in an area where most concentrates from alluvium contain from 1 to 5 percent of monazite. Tributaries entering the central reaches of North Muddy Creek between Glenwood and Caleb Branch are commonly devoid of monazite. Con- centrates contain as much as 10 percent of monazite along North Muddy Creek and Glade Creek to the northwest of Glenwood, along the middle part of Shadrick Creek, along South Muddy Creek near the mouth of Southeast Muddy Creek, and upstream along Southeast Muddy Creek. Concentrates having 20 per- cent of monazite come mainly from the Dysortville area on Southeast Muddy Creek and from South Muddy Creek at the mouth of Long Branch. Most concentrates from alluvium in the basin of South Muddy Creek have less than 40 percent of ilmenite, and concentrates from western headwater tributaries in the Demming area have less than 30 percent of ilmenite (A. M. White, written commun., 1954). Concentrates from tributaries to North Muddy Creek commonly have about 50 percent of ilmenite. Magnetite makes up 5—10 percent of the concentrate from alluvium in the extreme eastern part of the basin and increases in abundance toward the west. It makes up as much as 70 percent of the concentrate in the Demming area. Epidote is virtually absent from concentrates from Glade Creek and the head of South Muddy Creek, but elsewhere concentrates contain 1—10 percent of epidote and locally 30 percent. Rutile forms less than 1 percent of the minerals in concen- trates throughout the basin. Sillimanite is scarce and sporadically distributed; it constitutes 1 percent of the concentrate at several isolated places along North Muddy Creek and Shadrick Creek. Kyanite is present in low percentages in concentrates from the northern tributaries to North Muddy Creek. Garnet occurs in most concentrates in small amounts, and hornblende is very common. Attention was early called to the common presence of xenotime in the placers around Demming and Gum Branch (Dennis, 1898, p. 494; Zodac, 1958) . Long, broad, and continuous flood plains on South Muddy Creek extend into the headwaters of the stream around Dysortville. The flood plains on South Muddy Creek join large but less continuous flood plains in the lower valley of North Muddy Creek. Most of the central part of the valley of North Muddy Creek THE GEOLOGIC OCCURRENCE OF MONAZITE lacks extensive fill, but for a few miles downstream from Glenwood and along headwater tributaries up- stream from Glenwood the valleys have broad and continuous flood plains. The headwater parts of North Muddy Creek and South Muddy Creek were mined for placer monazite in the late 1800’s and early 1900’s (N itze, 1895c; Pratt, 1902, p. 60). Long Branch, Alexander Branch, Mac- Lawrath Branch, Gum Branch, the Dysortville area, and the Demming area were mentioned as sites of former mining, but apparently the large valleys were not mined. Most of the gold in this area was said to be mined out by 1905 (Pardee and Park, 1948, pl. 14). These valleys along with the small streams were ap- praised by A. M. White in the summer of 1952, and the large flood plain on South Muddy Creek was drilled by the US. Bureau of Mines in October of that year (Hansen and White, 1954, p. 4). White estimated that the basin of Muddy Creek contained at least 18,500 short tons of monazite in alluvium having an average tenor of 0.6 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). According to White, this resource is mainly in South Muddy Creek and its tributaries, par- ticularly the part of the basin around Dysortville (A. M. White, written commun., 1954) : Average tenor .Resourcea (lb o/mmmzite m monazite per cu yd) (short tom) Shadrick Creek ________________________ 0. 5 420 Glade Creek and Camp Branch __________ . 6 1, 350 North Muddy Creek to mouth of Glade .4 600 Creek ______________________________ North Muddy Creek from mouth of Glade Creek to Caleb Branch _______________ . 3 950 Lower part of North Muddy Creek includ- ing tributary from Nebo ______________ . 4 1, 600 South Muddy Creek and Katy Creek- - _ _ . 7 1, 400 Southeast Muddy Creek and Magazine Branch to a point 3,000 feet downstream from mouth of Magazine Branch (Dy- sortville area) ________________________ 1. 5 5, 000 South Muddy Creek from mouth of Katy Creek to a point 4,500 feet downstream from mouth of Long Branch including Alexander Branch, Southeast Muddy Creek from a point 3,000 feet down- stream from Magazine Branch, and Long Branch ________________________ . 8 4, 100 South Muddy Creek from a point 4,500 feet downstream from mouth of Long Branch to confluence with North Muddy Creek, and Muddy Creek to the Catawba River ______________________ . 4 l, 750 Other streams _________________________________ 1, 330 Total ___________________________________ 18, 500 These tenors are, of course, substantially lower than the tenors of gravel in the small streams formerly NORTH CAROLINA mined for monazite. Gravel from Alexander Branch was found by Mertie (1953, p. 8, 10) to contain 5.4 pounds of monazite per cubic yard. The large flood plain on South Muddy Creek down- stream from Southeast Muddy Creek to a point about 1.3 miles upstream from the confluence with North Muddy Creek was explored by the U.S. Bureau of Mines and found to contain about 5,800 short tons of monazite in alluvium having an average tenor of 0.6 pound of monazite and 3—5 cents worth of gold per cubic yard (Hansen and White, 1954, p. 6). Eleven churn-drill holes in the flood plain disclosed that the weathered bedrock floor of the valley is remarkably level, that the flood plain sediments are 15.5—19.0 feet thick, and that the sediment is mainly fine grained. The amount of monazite in the alluvium was found to decrease from about 0.75 pound per cubic yard in the upstream part of the area explored to about 0.5 pound in the downstream part of the flood plain. The average amount of black sand is 8 pounds per cubic yard con- sisting of the following percentages of the concentrate (Hansen and White, 1954, p. 15) : Percent Percent Epidote ____________ 17 Monazite ___________ 6. 4 Ilmenite ___________ 23 Rutile _____________ 0. 1— 0. 5 Quartz _____________ 21 Sillimanite and ky- Garnet _____________ 5 anite ____________ Trace Homblende _________ 6 Xenotime __________ 1 Magnetite __________ 9 Sphene _____________ 1 Zircon _____________ 8 Very small amounts of pyrite, spinel, tourmaline, and mica are also present. Inferred reserves of other components in the black sand were estimated to be 18,300 short tons of ilmenite, 4,100 short tons of garnet, and 6,300 short tons of zircon (Hansen and White, 1954, p. 24). High-grade monazite concentrates from Gum Branch were said to contain 3.30 percent of Th02 (Nitze, 1895c), and commercial concentrates from Long Branch, Alexander Branch, and MacLawrath Branch were reported by Pratt (1902, p. 60) to con~ tain 1.27, 6.30, and 2.48 percent of monazite respec— tively. Monazite from Alexander Branch was anal- yzed by the U.S. Geological Survey and found to con- tain 3.60 percent of ThOz and 0.27 percent of U308 (Mertie, 1953, p. 8, 12). An analysis of monazite from South Muddy Creek was reported by the U.S. Bureau of Mines to disclose 4.3 percent of Th02 and 0.36 percent of U303 (Hansen and White, 1954, p. 21). RUTHERFORD, POLK, AND CLEVELAND COUNTIES Fluvial gold placers near Rutherfordton in Ruther- ford County were the source in 1849 of the first mona— zite described from North Carolina (Shepard, C. U., 1849, p. 275; 1852, p. 109). In later years, around 238-813—67—15 217 1890, when an independent monazite mining industry developed in the State, gold placers in the headwaters of the Second Broad River and First Broad River in and along the south flank of the South Mountains in Rutherford County and Cleveland County were the source of some monazite (Nitze, 1895c; Pratt, 1903, p. 181). Similarly, fluviatile gold placers were the first sites of monazite mining in Polk County, where the Morris mine and Prince mine near Sandy Plains were worked for monazite in the late 1800’s (Genth and Kerr, 1881, p. 115; Genth, 1891, p. 86). At many gold placers the concentrates contained large quan- tities of magnetite, epidote, and hornblende derived from hornblende gneiss. Processing these concen— trates for monazite would have been uneconomic had not the extra cost been offset by the value of the gold (Pratt, 1907b, p. 113). As the monazite industry developed gold placers were abandoned and fluviatile deposits that were workable for monazite alone were opened. Placers mined strictly for monazite charac- teristically have little or no magnetite, epidote, horn- blende, or gold. These placers lie to the southeast of the monazite-bearing auriferous deposits. They occur in the core of the monazite belt, whereas the auriferous placers are along the northwest flank of the belt. The monazite placers in Rutherford County and Cleveland County were among the most productive in the State and probably accounted for at least half the monazite mined in North Carolina. Records by county are not available, but Cleveland County was probably the greatest producer (table 58). The output of monazite in Polk County apparently was an insignifi- cant part of the total. Frequently mentioned centers for the monazite-mining industry were Rutherfordton, Ellenboro, Oak Springs, Bostic, Spindale, and Hen- rietta in Rutherford County (Pratt, 1903, p. 182; 1904c, p. 35; Drane and Stuckey, 1925, p. 19; Bryson, 1927, p. 15—16) ; Sandy Plains in Polk County (Genth, 1891, p. 86); and Belwood, Carpenter Knob, Casar, Lawndale, Mooresboro, and Shelby in Cleveland County (Nitze, 1895c; Sterrett, 1908b, p. 281; Drane and Stuckey, 1925, p. 19; Bryson, 1927, p. 15—16). During the life of the monazite industry the most thorough studies of the geology of the placers were made by Sterrett (1908b, p. 273—280) and Pratt and Sterrett (1908a), who described the small size and sparseness of gravel in individual placers but wide geographic distribution of the deposits. After the industry closed in 1917, scant attention was paid to the deposits until the 1940’s and 1950’s, although a little prospecting and development were done in Cleveland County between 1929 and 1936 (Bryson, 1937, p. 132). In 1943 and 1944 nearly two dozen 218 placers in Rutherford County and Cleveland County were examined by members of the Regional Products Research Division of the Tennessee Valley Authority, and the deposits were seen to constitute a minable resource under conditions of critical short supply (McDaniel, 1943; Lefi'orge and others, 1944). During 1945, Mertie (1953, p. 7—12) sampled 9 placers in Rutherford County and 21 in Cleveland County. He found that the tenor of the gravel in deposits in Rutherford County ranged from 5.1 to 26.5 pounds of monazite per cubic yard and in deposits in Cleveland County from 3.1 to 48.3 pounds of monazite per cubic yard. The average tenor of gravel in the 9 placers in Rutherford County was found to be 13.1 pounds of monazite per cubic yard and in the 21 placers in Cleveland County 12.2 pounds per cubic yard. Thor- ium oxide in detrital monazite was reported by Mertie (1953, p. 12) to range from 4.47 to 5.80 percent and to average 5.16 percent in 9 samples from Rutherford County and to range from 4.62 to 7.84 percent and to average 6.19 percent in 21 samples from Cleveland County. Between 1951 and 1954 the monazite-bearing streams in Rutherford, Polk, and Cleveland Counties were examined by P. K. Theobald, Jr., J. W. Whit- low, A. M. White, and the writer, all of the U.S. Geo- logical Survey, for the US. Atomic Energy Commis- sion. As a result of this appraisal the resources in monazite in the three counties were estimated to be at least 285,000 short tons of monazite in fluvial sedi- ments having an average tenor of 1.0 pound of mona- zite per cubic yard (Overstreet, Theobald, and Whit- low, 1959, p. 711). This examination also disclosed the distribution of monazite and other heavy minerals in the three counties. Monazite is present in concentrates from alluvium in most streams in Rutherford County, except those in the extreme northwestern part (Overstreet, 1962, fig. 2). It occurs in concentrates from alluvium in the southeast corner of Polk County. Concentrates from stream sediments throughout Cleveland County, except the extreme southeastern part, are monazite bearing. In Rutherford and Cleveland Counties the core of the monazite belt attains its maximum width of 26 miles, and the belt itself is 40 miles wide. The northwest edge of the core of the belt extends northeastward from the south edge of Polk County at a point about 4 miles west of the Rutherford County line. It then passes about 2 miles east of Rutherford on to the mutual boundary of Rutherford County, Cleveland County, and Burke County in the South Mountains. South- east of this line across Rutherford County and almost all of Cleveland County, concentrates from alluvium THE GEOLOGIC OCCURRENCE OF MONAZITE contain 10—40 percent of monazite and very locally as much as 60 percent. The northwest flank of the belt, which is marked by concentrates having as much as 10 percent of monazite, is 10—14 miles across in Ruth- erford and Polk Counties, but the southeast flank in Cleveland County is only 1—5 miles wide. Rutile is present in slightly more than half the con- centrates from alluvium in the core of the monazite belt in Rutherford, Polk, and Cleveland Counties, but it is virtually absent from concentrates from the flanks. It is most commonly present in concentrates from eastern Rutherford County, extreme southeastern Polk County, and southwestern, central, and north- western Cleveland County. In most of these places rutile makes up 1—5 percent of the concentrate, but in central Cleveland County it makes up 5—10 percent. Sillimanite makes up from 1 to 5 percent of the heavy minerals in concentrates from the core of the monazite belt, but it is absent from concentrates from streams on the flanks of the belt. Over most of cen- tral Cleveland County and in the southwest corner of the county, concentrates contain 5—10 percent of silli- manite, and locally they have as much as 15—25 per- cent. Along the central part of the south edge of Rutherford County, concentrates are devoid of silli- manite. On the southeast flank of the monazite belt at the south edge of Cleveland County, sillimanite is accompanied by kyanite (Overstreet and Griflitts, 1955, fig. 1). _ Almandine and ilmenite are much more common in concentrates from alluvium in the core of the belt than in concentrates from the flanks. Most concen- trates from eastern Rutherford County and western Cleveland County contain 5—15 percent of garnet and 50—70 percent of ilmenite. Elsewhere the percentages are lower. Epidote is common in concentrates from alluvium along the northwest flank of the monazite belt in Rutherford County and Polk County, but it is Virtu— ally absent from the core of the belt. It is absent from concentrates from the southeast flank of the belt in Cleveland County. Staurolite is very common in con- centrates from the southeast flank but is virtually ab- sent elsewhere (Overstreet and Griffitts, 1955, fig. 1). Magnetite rarely makes up more than 1 percent of the heavy minerals in concentrates from alluvium in the core of the belt or from alluvium in the southeast flank in Cleveland County, but it is present in amounts of from 5 to 50 percent of concentrates along the northwest flank in Rutherford County and Polk County. Locally as much as 80 percent of the min- erals in the concentrate is magnetite. NORTH CAROLINA Hornblende is generally present in concentrates from the northwest flank of the belt in Rutherford and Polk Counties, and it rises to a peak abundance of 40 percent in concentrates from auriferous areas along the southern slopes of the South Mountains in Rutherford County, but it is not present in concen- trates from the core of the belt. Concentrates from the southeast flank of the belt in Cleveland County contain as much as 5 percent of hornblende (Over— street and Griflitts, 1955, fig. 1). The appraisal of resources of monazite in the three counties was based on the study of eight drainage basins or groups of basins (Overstreet, Theobald, and Whitlow, 1959, p. 711): Mountain Creek, Catheys Creek, Floyds Creek, Hinton Creek, McKinney Creek, Knob Creek, Sandy Run, and Buffalo Creek. The first four basins are mainly in Rutherford County; the McKinney Creek area includes parts of Ruther- ford and Polk Counties; and the last three basins are principally in Cleveland County. Mountain Creek and other tributaries to the Broad River in west—central Rutherford County were esti- mated by Theobald to contain at least 6,800 short tons of monazite in flood-plain sediments having an average tenor of 0.5 pound of monazite per cubic yard (Over- street, Theobald, and Whitlow, 1959, p. 711). Flood plains in the area are small and disconnected. The streams are on the northwest flank of the monazite belt in an area where concentrates consist dominantly of magnetite, epidote, and hornblende. The Catheys Creek area includes Cane Creek and other streams constituting the upstream half of the Second Broad River in north-central Rutherford County and southeastern McDowell County. These streams rise on the south side of the South Mountains opposite the headwaters of Muddy Creek and Silver Creek. Most of the area drained by Catheys Creek and adjoining tributaries to the Second Broad River is on the northwest flank of the monazite belt; only the southeasternmost part of the area‘ is in the core of the belt. Magnetite, epidote, and hornblende are the most common minerals in concentrates. The average tenor of flood plain sediments was estimated by Theo- bald (Overstreet, Theobald, and Whitlow, 1959, p. 711) to be 0.7 pound of monazite per cubic yard, and the resources in monazite were said to be at least 36,800 short tons. Four holes were drilled by the U.S. Bureau of Mines during February 1952 in the flood plain at the con— fluence of Catheys Creek with the Second Broad River, and three holes were drilled in the lower and 219 middle reaches of Cane Creek. Results of the drill- ing on Catheys Creek showed that the alluvium ranged in thickness from 19 to 23.5 feet and contained from 6.52 to 14.35 pounds of black sand per cubic yard including 0.27—0.91 pound of monazite and persistent small amounts of gold (R. F. Griffith, written com- mun., 1952). Results of the drilling on Cane Creek showed that the flood-plain sediments ranged in thick- ness from 17.5 to 21 feet and contained from 12.30 to 16.49 pounds of black sand per cubic yard having 0.38—0.52 pound of monazite and small amounts of gold. Cane Creek has the longest, largest, and most continuous flood plain in the area. In volume, tenor, and presence of gold the alluvium in the valley of Cane Creek resembles that in Muddy Creek and Silver Creek. Also, several gold placers at the head of Cane Creek were said to have been mined out by 1905 (Pardee and Park, 1948, pl. 14). Two samples of monazite from Hollands Creek, a principal tributary to Catheys Creek, were analyzed by the U.S. Geological Survey and reported by Mertie (1953, p. 12) to contain 5.27 and 5.49 percent of Th02 and 0.22 and 0.25 percent of U308. Floyds Creek and several small tributaries to the Broad River in southeastern Rutherford County were estimated by P. K. Theobald, Jr., to contain at least 42,700 short tons of monazite in sediments which along the small streams have an average tenor of 1.1 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). The area is in the core of the monazite belt and concentrates have as much as 50 percent of monazite (Overstreet, 1962, fig. 2). Ilmenite and garnet are invariably present in the con- centrates, sillimanite is present in about 85 percent of the concentrates, and rutile occurs in about half of them (P. K. Theobald, Jr., written commun., 1954). Magnetite, epidote, and hornblende are scarce except in the westernmost streams which rise on the flank of the monazite belt. The largest volume of alluvium in the Floyds Creek area was reported (P. K. Theobald, J r., written com- mun., 1954) to be in discontinuous flood plains along the Second Broad River and in long, continuous flood: plains in the valleys of south-flowing tributaries to the Second Broad River, principally Robinson Creek, Heaveners Creek, Hunting Creek, Puzzle Creek, and Webb Creek. East-flowing tributaries to the Second Broad River are very small, and south-flowing trib- utaries to the Broad River, of which Floyds Creek is one, have small, discontinuous flood plains. Accord- ing to Theobald, the average tenor of the alluvium 220 and the resources in monazite in the valleys of these streams are as follows: Average tenor Resources (lb of monazite (short per on 741) tons) Second Broad River ____________________ 0. 5 7, 000 Robinson Creek and Heaveners Creek to to the mouth of Heaveners Creek ______ 1. 4 6, 800 Robinson Creek from the mouth of Heaveners Creek to the Second Broad River ______________________________ 1. 7 6, 500 Hunting Creek ________________________ 3. 2 1, 300 Puzzle Creek __________________________ 3. 2 4, 600 Webbs Creek __________________________ 2. 7 2, 500 Floyds Creek __________________________ 1 1 5, 500 Other streams _________________________________ 8, 500 Total ___________________________________ 42, 700 Gold was formerly mined in the area around the head of Robinson Creek. The mouth of the creek is near Bostic and east of Spindale; both communities were at one time noted centers for monazite placer mining. Puzzle Creek passes east of Bostic, and Webbs Creek lies west of Ellenboro, another of the frequently cited centers for monazite mining in Ruth- erford County. Many small streams not impressive for the size of their valleys but apparently mined in a small way are around Henrietta. Monazite sand from Henrietta was said by Pratt (1903, p. 182) to contain 1.93 percent of Th02. Seem- ingly the reference is to a rough concentrate, because a sample of monazite from a short tributary to the Second Broad River about 2 miles north of Henrietta was reported by Mertie (1953, p. 12) to have 4.74 per- cent of Th02 and 0.64 percent of U308. Two samples of monazite from Webbs Creek were said by Mertie to contain 4.47 and 5.76 percent of Th02 and 0.34 and 0.40 percent of U308. Hinton Creek and other headwater tributaries to the First Broad River rise in northeastern Rutherford County and northwestern Cleveland County on the south side of the South Mountains. The northwest- ernmost headwater branches of the First Broad River, streams called Sally Queen Creek, Hardbargain Branch, Beatty Creek, Molly Fork, and South Creek, rise along the northwest edge of the core of the mona- zite belt in an area where concentrates from alluvium contain copious garnet and ilmenite associated with some sillimanite and low percentages of magnetite, epidote, and hornblende (Overstreet and Grifl‘itts, 1955, fig. 1). Most of these streams were formerly mined for gold; some were mined out by 1905 (Pardee and THE GEOLOGIC OCCURRENCE OF MONAZITE Park, 1948, pl. 14). East of the mouth of South Creek, alluvium in the principal tributaries to the First Broad River, known as Brier Creek, Duncans Creek, and Hinton Creek, contains little or no mag- netite, epidote, hornblende, and gold. Concentrates from these streams consist mainly of garnet, ilmenite, monazite, and sillimanite. Alluvium along these streams was estimated by P. K. Theobald, J r., to con- tain at least 39,000 short tons of monazite and to have an average tenor of 1.3 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). These resources were inferred by Theobald (written c0mmun., 1954) to be mainly in the First Broad River, Duncans Creek, and Hinton Creek: Average tenor Resources (lb of monazite (short per cu yd) tons) Molly Fork ___________________________ 1. 2 400 Hardbargain Branch ___________________ . 8 400 Somey Creek and the upper part of the First Broad River ____________________ 1. 2 l, 500 North Fork ___________________________ . 4 300 South Creek __________________________ 1. 2 1, 600 First Broad River for a distance of 3.5 miles downstream from mouth of North Fork _______________________________ . 7 3, 500 First Broad River from the above locality to the mouth of Brier Creek ___________ 2. 4 6, 000 Brier Creek ___________________________ . 8 600 Duncans Creek ________________________ 2. 3 11, 000 First Broad River from 0.75 mile east of the Rutherford County line to the mouth of Hinton Creek _____________________ . 8 5, 500 Hinton Creek _________________________ l. 6 8, 000 Other streams _________________________________ 200 Total ___________________________________ 39, 000 During the winter of 1951 and the late fall of 1952 the US. Bureau of Mines sank 52 churn-drill holes in the flood plain of the First Broad River between Hin- ton Creek and a point 1.4 miles above the mouth of Duncans Creek and in contiguous alluvium along the lower parts of Hinton, Duncans, and Wards Creeks in Cleveland County just downstream from the Ruth- erford County line (Hansen and Cuppels, 1954, p. 10). Results of the drilling showed that the flood plain sediments contain about 7,200 short tons of monazite (table 71). From 2 to 3 percent of epidote was pres- ent in concentrates from the First Broad River, and 1 percent was observed in concentrates from Wards Creek, but only a trace was present in black sand from Hinton Creek and Duncan Creek (Hansen and Cup— pels, 1954, p. 17). Only traces of magnetite were found. NORTH CAROLINA TABLE 71.—Reserves of monazite and other minerals in alluvium in the valley of the First Broad River and contiguous parts of the valleys of Words Creek, Duncans Creek, and Hinton Creek, Cleveland County, NC. [Modified from Hansen and Cuppels (1954, p. 5, 10, 14, 24). Symbols used: -_, ab- sent; NA, not applicable] First Wards Duncans Hinton Feature Broad Creek Creek Creek Total River Number of churn drill holes..__ 24 11 6 11 52 Minable material: Thickness _____________ feet. _ - 24 18 28 18 NA Tenor. -lb monazite per cu yd. _ . 85 72 . 74 . 72 NA Gravel: Thickness ............. feet..- 7 9 l3 5 N A Tenor.-lb monazitepereuyd.. 1. 2 1 2 1. 5 1 5 NA Volume of alluvium thousands of cu yd-. 9, 681 3, 183 1, 648 3, 750 18, 262 Partial composition of concen- trate (percent): Monazite .................... 7. 8 8. 8 3. 2 6. 5 NA Ilmenlte ..................... 31 40 24 35 NA Garnet ....................... 31 27 14 26 NA Sillimanite and kyanite ...... 12 10 16 13 NA Zircon ....................... 3. 5 3. 5 -- 3 5 NA Rutile ....................... 2 1. 5 .- 4 5 NA Reserves (short tons): 1, 140 610 1, 353 7, 218 8, 000 5, 000 7, 000 50, 000 5,500 2, 500 5 000 43, 000 2, 000 3, 000 2, 600 19, 600 700 _- 700 4, 800 300 -- 900 3, 200 Monazite from the area drilled was analyzed by the U.S. Bureau of Mines and was reported to contain the following percentages of thorium oxide (Hansen and Cuppels, 1954, p. 21): Percent Tho. U303 First Broad River ____________________________ 5. 91 0. 50 Wards Creek ________________________________ 5. 94 . 76 Duncans Creek ______________________________ 6. 66 . 62 Hinton Creek _______________________________ 5. 42 . 59 Two samples of monazite from southern tributaries to Duncans Creek at localities 1% miles and 2% miles north of Hollis, Rutherford County, were analyzed by the U.S. Geological Survey and reported to have respec- tively 5.28 and 5.02 percent of Th02 and 0.33 and 0.28 percent of U308 (Mertie, 1953, p. 12). Early predictions that every stream in Polk County would prove to be monazite bearing (Genth and Kerr, 1881, p. 84) were not borne out, and later investiga- tions showed that monazite is common only in the eastern part of the county (Eng. and Mining Jour., 1888, p. 2; Nitze, 1895c). Much of the monazite in the Sandy Plains area in south-central Polk County is in auriferous placers on tributaries to the Pacolet River that rise south of the divide on which Sandy Plains is located and flow into South Carolina (Genth and Kerr, 1881, p. 115; Genth, 1891, p. 86; Pardee and Park, 1948, p. 85). Tributaries to the Broad River north and east of Sandy Plains are also monazite bear- ing. The largest of these streams in Polk County are Wheat Creek, Machine Creek, Whiteoak Creek, Mill 221 Creek and Greens Creek, which enter the Green River, a major southern tributary to the Broad River, and McKinney Creek which is confluent with the Broad River in Rutherford County. An estimate prepared by A. M. White showed that these streams have at least 3,600 short tons of monazite in alluvium having an average tenor of 0.5 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). Only the easternmost streams, Greens Creek and McKinney Creek, are in the core of the monazite belt. Alluvium in these two streams was estimated by A. M. White (written commun, 1954) to have average tenors of 1.1 and 0.7 pounds of monazite per cubic yard, re- spectively. The other streams are on the northwest flank of the monazite belt; their alluvium was estimated by White to have the following average tenors: Average tenor Resource: (lb of monazite (short per cu yd) tons) Wheat Creek __________________________ 0. 1 30 Machine Creek ________________________ . 4 115 Whiteoak Creek _______________________ . 3 1, 500 Mill Creek ____________________________ . 6 270 Greens Creek __________________________ 1. 1 900 McKinney Creek ______________________ 7 650 Other streams _________________________________ 135 TotaL __________________________________ 3, 600 None of these streams was an important source of monazite, and Polk County contributed little to the State output of monazite. Knob Creek and other tributaries to the First Broad River in Cleveland County downstream from Wards Creek to Big Harris Creek were estimated by P. K. Theobald, J r., to have at least 45,000 short tons of monazite in alluvium which has an average tenor of 2.1 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). The high average tenor of alluvium in the Knob Creek area is equaled elsewhere in the western monazite belt only by alluvium in Huff Creek and adjacent streams in the drainage basin of the Reedy River in Greenville County, SC. (Overt-street, Theobald, and Whitlow, 1959, p. 710). Knob Creek, like the Hufl? Creek area, is in part of the core of the monazite belt where most concentrates contain 20—40 percent of monazite al- though some contain 60 percent (Overstreet, 1962, fig. 2). Biotite schist and gneiss, sillimanite schist, and quartz monazite are the principal varieties of rocks underlying the drainage basins in the Knob Creek area. Concentrates that have the greatest amount of monazite come from basins underlain by quartz mon- zonite and sillimanite schist. For the most part the 222 concentrates consist mainly of garnet, monazite, ilmen- ite, sillimanite, and rutile, but at several places where gabbro and hornblende gneiss are present, as on Bob Branch and near the heads of Maple Creek and Wards Creek, magnetite is common. Most of the flood plains in the Knob Creek area, in— cluding those in the valley of the First Broad River, are narrow and discontinuous (P. K. Theobald, Jr., written commun., 1954). The broadest flood plains are at the confluence of Big Knob Creek and Little Knob Creek where a maximum width of about 1,000 feet is attained. Many of the narrow flood plains ex- tend far up toward the sources of the streams. The thickness of gravel in the sequence of flood plain sedi- ments remains about the same from the main valleys to the heads of the streams, but the silt and clay above the gravel decreases headward to about one-third its thickness in the main valleys. Mostly the basal gravel is about 0.5—1.5 feet thick, and the overlying clay, silt, and sand ranges in thickness from a maximum of about 15 feet in the main streams to 2—5 feet in the headwaters. In the Knob Creek area the flood plain sediments consist of about 17 percent gravel, 23 per- cent clay, and 60 percent sand and silt. Riffle gravel from about one-third of the streams in the area was reported by P. K. Theobald, Jr. (written commun., 1954) to contain 5 pounds or more of mona— zite per cubic yard, and the maximun tenor observed was 31.7 pounds of monazite per cubic yard. Seven out of ten samples of rifiie gravel panned by Mertie (1953, p. 10) from formerly mined creeks in the area contained from 7.8 to 30.4 pounds of monazite per cubic yard. The average tenor of the flood plain sediments between grass roots and bedrock was found by Theobald to be appreciably less than 5 pounds of monazite per cubic yard except along Crooked Run Creek: Average tenor Resources (lb of monazite (short per cu yd) tons) Wards Creek __________________________ 1. 6 6, 000 Stoney Run Creek _____________________ 4. 4 1, 600 Grassy Branch ________________________ 2. 4 1, 200 Crooked Run Creek ____________________ 5. 9 6, 500 Big Knob Creek _______________________ 2. 4 14, 000 Poundingmill Creek ____________________ 3. 6 1, 900 Bob Branch ___________________________ 3. 1 1, 700 Little Knob Creek _____________________ 2. 0 6, 400 Knob Creek ___________________________ . 6 900 Maple Creek __________________________ . 6 900 Magness Creek ________________________ . 9 350 Big Harris Creek ______________________ 2. 1 650 Little Harris Creek ____________________ 1. 7 700 First Broad River ______________________ . 7 1, 900 Other streams _________________________________ 300 Total ___________________________________ 45, 000 THE GEOLOGIC OCCURRENCE OF MONAZITE The large flood plain on Big Knob Creek extending for 2 miles upstream from the mouth of Poundingmill Creek was drilled by the U.S. Bureau of Mines in November and December 1951 and was found to con- tain 3,330,000 cubic yards of minable alluvium having 2,780 short tons of monazite, 11,700 short tons of garnet, 7,700 short tons of ilmenite, and 330 short tons of zircon (Griffith and Overstreet, 1953a, p. 4—5). The average tenor in monazite is 1.67 pounds of mona- zite per cubic yard of alluvium. Gravel at the base of the sequence of flood plain deposits is about four times richer in monazite than the overlying fine sand and silt, but even those sediments contain about 0.9 pound of monazite per cubic yard. One hole was drilled to a depth of 20.5 feet in col- luvium on a spur of Carpenter Knob 1 mile north of the north end of the explored flood plain. The aver- age tenor of the colluvium sampled at this site is 1.83 pounds of monazite per cubic yard (Griffith and Over- street, 1953a, p. 18). Seven samples of colluvial sub- soil from the drainage basin of Knob Creek were re- ported by J. W. Whitlow (written commun., 1954) of the U.S. Geological Survey to have the following average tenor: [Computed by J. W. Whitlow from mineralogical analyses by M. N. Glrhard, H. B. Groom, Jr., R. P. Marquiss, C. J. S engler, Jerome Stone, and E. J. Young of the U.S. Geological Survey Tenor Laboratory (lb of mono- No. zite per cu mi) 88476 ___________________________________ 1. 6 90320 ___________________________________ . 2 9 032 1 ___________________________________ . 2 90331 ___________________________________ 6. 8 90332 ___________________________________ 2. 8 90357 ___________________________________ . 1 9 03 58 ___________________________________ 1 O. 1 Average ___________________________ 3. 1 Monazite sands of undescribed purity from the Carpenter Knob area and Belwood were reported by Pratt (1903, p. 182) to have respectively 6.26 and 5.87 percent of Th02. In 1908 an analysis was made of monazite concentrate thought by L. G. Houk to be from Belwood in the Knob Creek area, but the amount of thorium oxide is very much lower than any known from this district: [Analystz G. P. T. Chemik in 1908 (in Honk, 1946, p 3)] Percent Percent 06203 ________________ 45. 40 F80 _________________ 3. 62 (La, Nd, Pr)203 _______ 6. 56 F8203 ________________ 5. 58 Y203 _________________ 2. 07 ZrOz _________________ 3. 25 ThOZ ________________ l. 22 (Nb, Ta)205 __________ 4. 12 P205 _________________ 23. 43 MnO ________________ Trace Si02 _________________ 1. 60 A1203 ________________ 2. 49 Total __________ 99. 34 Analyses were made by the U.S. Geological Survey of monazite collected by Mertie (1953, p. 12) in 1945 NORTH CAROLINA at placers in the Knob Creek area. Results of these analyses showed that monazite from Knob Creek and vicinity contained from 5.08 to 7.84 percent of Th02: Percent Th0: U303 Poundingmill Creek __________________________ 6. 80 O. 39 Big Knob Creek _____________________________ 7. 00 . 29 Bald Knob Creek ____________________________ 5. 66 . 36 Little Knob Creek ___________________________ 7. 84 . 35 Knob Creek _________________________________ 7. 06 . 34 Knob Creek _________________________________ 5. 08 . 40 Maple Creek ________________________________ 7. 22 . 28 Grassy Branch ______________________________ 5. 31 . 49 Crooked Run Creek __________________________ 7. 54 . 37 Crooked Run Creek __________________________ 6. 45 . 32 Monazite from the drilled area on Big Knob Creek was analyzed by the U.S. Bureau of Mines and found to contain 7.28 percent of T1102 and 0.42 percent of U308 (Griffith and Overstreet, 1953a, p. 26). The results of these analyses, plus the ones made on mona- zite separated from crystalline rocks in this part of Cleveland County and previously cited (tables 64— 68), indicate that the material analyzed by Chernik and attributed by Houk to sources around Belwood is too lean in thorium oxide to have come from that area. Sandy Run rises in eastern Rutherford County and flows southeastward into Cleveland County where it enters the Broad River. Its extreme headwaters are on the northwest flank of the monazite belt, but for most of its length Sandy Run is in the sillimanitic core of the monazite belt. Immediately east of Sandy Run are two large streams known as Brushy Creek and Beaverdam Creek. They are western tributaries to the First Broad River. Both of these streams drain part of the core of the monazite belt, and concentrates from sediments in their valleys, like concentrates from most parts of Sandy Run, contain 10—30 percent of monazite, abundant ilmenite and garnet, and accessory rutile and sillimanite. Epidote is absent and magne- tite is sparse. Concentrates from the extreme head of Sandy Run east of Hopewell contain only 5—10 per- cent of monazite. Alluvium in small branches and creeks in the headward parts of these streams was formerly mined by hand methods for detrital mona- zite. Most of the mining was along branches of Sandy Run in the vicinity of Hopewell, Lattimore, Moores- boro, and Ellenboro, Brushy Creek south of Polkville, and Beaverdam Creek east of Lattimore. The Ger- man-American Monazite Co. was reported to have mined a headwater tributary to Sandy Run about 11/8 miles north-northwest of Hopewell (Mertie, 1953, p. 8). v 223 Monazite sand of unknown tenor from the Davis mine near Mooresboro was said to have 3.98 percent of Th02 (Pratt, 1903, p. 182). Somewhat more thor- ium oxide than this seems to be characteristic of pure monazite from the area. Sampling in 1943 and 1945 of formerly mined placers on Sandy Run, Brushy Creek, and Beaverdam Creek showed that gravel in these deposits contained from 3.6 to 26.5 pounds of monazite per cubic yard and that the monazite had from 4.58 to 5.86 percent of ThO2 (Lefiorge and others, 1944; Mertie, 1953, p. 7—8, 10, 12). Monazite from placers in Cleveland County [Analyst: U.S. Geo]. Survey except first entry, which was by Dept. Chem. Eng., Tenn. Valley Authority] Tenor of Composition of monazite rifl‘le gravel (percent Stream (1b of monazite per cu yd) Th0: U198 Sandy Run _________________________ 5. 15 __________ 4. 5 5. 58 0. 33 12. 8 5. 86 . 28 5. 5 5. 52 31 12. 7 5. 80 . 28 26. 5 4. 58 . 33 Brushy Creek _____________ 3. 6 5. 06 . 53 10. 6 4. 62 . 55 Beaverdam Creek _________ 8. 9 5. 08 . 54 Average of above____ 10. 6 5. 25 . 39 An appraisal of Sandy Run, Brushy Creek, and Beaverdam Creek was made in the summer of 1951 by P. K. Theobald, J r., of the U.S. Geological Survey, who estimated that the valleys of the streams con- tained at least 66,300 short tons of monazite in sedi- ments having an average tenor of 1.6 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). Theobald observed that sediments hav- ing the highest tenor (written commun, 1954) were in valleys at the head of Sandy Run from Hopewell southeast to Lattimore and southwest to Ellenboro, in the northern tributaries to Brushy Creek east of Washburn, and at the head of Beaverdam Creek south- east of Lattimore: Average tenor Resources (lb of monazite (short per cu yd) tom) Sandy Run headwaters east of Hopewell and south to mouth of Mayne Creek-" 3. 5 15, 200 Mayne Creek _________________________ 3. 8 5, 000 West Fork west of Hopewell and south to Sandy Run near mouth of Mayne Creek- 2. 0 11, 400 Sandy Run from Mayne Creek to the Broad River ________________________ 1. 4 8, 600 Grog Creek ___________________________ . 5 900 Brushy Creek headwaters to mouth of Little Creek _________________________ 1. 4 4, 900 Little Creek ___________________________ 2. 6 900 224 Average tenor (lb of monazite Resources per cu yd) (short tons) Northern tributaries to Brushy Creek east of Washburn ________________________ 3. O 1, 900 Brushy Creek from Little Creek to the First Broad River ____________________ . 6 2, 300 Beaverdam Creek headwaters including Sugar Branch _______________________ 1. 6 6, 000 Lower part of Beaverdam Creek _________ 1. 3 2, 000 Yancey Creek _________________________ 2. 3 900 Other streams _________________________________ 6, 300 Total ___________________________________ 66, 300 An area of connected flood plains near the head of Sandy Run at a point 0.9 mile east of Hopewell was explored by the US. Bureau of Mines in January and February 1952 (Griffith and Overstreet, 19530, p. 4—5). Results of the drilling showed that the average tenor of the gravel in the lower one-third of the sequence of flood plain sediments is 3.3 pounds of monazite per cubic yard and that the silt and fine sand overlying the gravel and making up two-thirds of the section of sedi- ment has an average tenor of 1 pound of monazite per cubic yard. From grass roots to bedrock the average tenor was estimated to be 1.63 pounds of monazite per cubic yard. The explored flood plains were estimated to contain 4 million cubic yards of sediment with com- bined indicated and inferred reserves of 3,300 short tons. The mineralogical composition of a composite concen- trate prepared from alluvium sampled at 30 drill holes in the headwaters of Sandy Run 0.9 mile east of Hope- well is as follows: [Modified from Griffith and Overstreet (1953c, p. 21)] Percent Percent Epidote ______________ Trace Zircon _______________ 0. 5 Hornblende and biotite- O. 5 Sillimanite ___________ 13. 3 Garnet _______________ 26. 5 Kyanite ______________ 2. 7 Ilmenite _____________ 34. 3 Monazite and Magnetite ____________ . 5 xenotime ___________ 6. 1 Quartz _______________ 8. 5 Rutile _______________ 5. 4 Total __________ 98. 3 Monazite from the explored area at the head of Sandy Run was analyzed by the US. Bureau of Mines and found to contain 4.63 percent of ThOz and 0.80 percent of U308 (Griflith and Overstreet, 19530, p. 25). Hickory Creek, an eastern tributary to the First Broad River in Cleveland County, was frequently mentioned in the early literature as the site of lode mining for monazite by the British Monazite Co. at the L. U. Campbell placer mine about 3 miles north- east of Shelby (Pratt, 1901, p. 31; 1907b, p. 118—119; Sterrett, 1907b, p. 1204—1205; Keith and Sterrett, 1931, p. 10). Present riffle gravel in Hickory Creek at the L. U. Campbell mine was reported by Mertie (1953, p. 7, 10) to contain 3 pounds of monazite per cubic THE GEOLOGIC OCCURRENCE OF MONAZITE yard, and gravel from a rifle on Little Hickory Creek at a point about 2 miles south of the L. U. Campbell mine was found by Mertie to have 3.9 pounds of mona~ zite per cubic yard. Presumably, monazite in the gravel at the mine was replenished between the time mining ceased around 1906 and 1945 when the gravel was sampled. Source of the replenishing monazite was principally the soil on hillsides adjacent to the stream. Analyses of detrital monazite from Hickory Creek at the L: U. Campbell mine and from Little Hickory Creek were made by the US. Geological Survey and showed 7.72 and 5.77 percent of Th02 and 0.33 and 0.98 percent of U303, respectively (Mertie, 1953, p. 12). Buffalo Creek rises in the northwest corner of Lin- coln County, flows southward through parts of Cleve- land County and Gaston County, and enters the Broad River in Cherokee County, 8.0. Most of its course is in Cleveland County. The headwaters of the stream originate in the core of the monazite belt, and as far south as the divide it shares with Hickory Creek in the vicinity of Stubbs, the stream and its tributaries are in the core of the belt. South of Stubbs the stream passes into the southeast flank of the monazite belt, and its eastern tributaries rise either in the flank of the belt or outside the belt. Where Buffalo Creek is in the core of the belt, concentrates from sediment in the valley contain 10—30 percent of monazite and locally as much as 60 percent. Concentrates from alluvium in the part of the stream on the flank of the belt have less than 10 percent of monazite, and those from the eastern tributaries south of Stubbs have either a trace of monazite or are barren. Rutile is common in concentrates from alluvium in the northern and central parts of the basin of Buffalo Creek, as much as 10 percent of rutile being present in a few concentrates. Sillimanite is also particularly abundant in concentrates in this part of the basin (Overstreet, 1962, fig. 1) ; locally it makes up as much as 20 percent of the concentrate. Garnet and ilmenite are common in the northern and central parts of the basin. Epidote is virtually absent from concentrates from Buffalo Creek, but staurolite is very common in the southern and southeastern parts of the basin (Overstreet and Grifiitts, 1955, fig. 1), where it makes up as much as 20 percent of the concentrate. Through- out most of the basin magnetite is either absent or constitutes only 1—5 percent of the concentrate. Near the mouth of Buffalo Creek, concentrates may contain as much as 40 percent of magnetite. Formerly mined placers on Buffalo Creek and its tributaries were sampled for monazite in 1943 (Lefl'orge and others, 1944). NORTH CAROLINA Composition of monazite from placers in Bufi'alo Creek Analyst: U.S. Geo]. Survey in 1945 (Mertie, 1953, p. 7-8, 10, 12) except first entry, which was made by the Dept. Chem. Eng., Tenn. Valley Authority] Tenor of Composition of riflie gravel monazite Stream (lb of mon- (percent) azite per cu yd) Th0: U303 Buffalo Creek _______________________________ 6. 80 ______ Bufl’alo Creek 2.25 miles north of Fallston __________________________ 6. 1 6. 46 0. 41 Bufialo Creek 1 mile northeast of Fallston __________________________ 2. 9 6. 34 . 45 Bufi'alo Creek 1.5 miles southeast of Fallston __________________________ 2. 2 7. 38 . 31 Long Creek _________________________ 1. 8 6. 13 . 38 Average ______________________ 3. 2 6. 62 . 39 The analyzed samples come from parts of the basin in which Toluca Quartz Monzonite is an important source of monazite. Where the source is mostly schist, the amount of thorium oxide in the monazite is less. Thus, monazite from the flood plain at the confluence of Buffalo Creek and the Broad River in Cherokee County, 8.0., analyzed by the US. Bureau of Mines, contains 4.64 percent of Th02 and 0.58 percent of U308 (Hansen and Theobald, 1955, p. 24). The amount of monazite in the main valley of Buf- falo Creek and its tributaries was estimated by the writer in 1951 to have an average tenor of 0.9 pound per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 711). The greatest resources in monazite and the highest average tenors are in the upper reaches of Buffalo Creek: Average tenor Resources (lb ofmonazite (short per cu yd) tons) Head of Buflalo Creek east of Toluca and downstream to Glen Creek ____________ 2. 6 8, 200 Glen Creek and major tributary _________ 1. 2 2, 700 Bufl'alo Creek from Glen Creek to Little Buffalo Creek _______________________ 1. 8 7, 500 Little Buffalo Creek ____________________ 1. 7 6, 000 Bufl’alo Creek from Little Buffalo Creek to Suck Creek _______________________ 1. 2 5, 500 Suck Creek ___________________________ 1. 4 2, 300 Buffalo Creek from Suck Creek to a point 1% miles upstream from Muddy Fork_- . 4 2, 900 Buffalo Creek from a point 0.5 mile up- stream from Muddy Fork to the Broad River ______________________________ . 2 5, 200 Boween River _________________________ 1. 4 4, 900 Total ___________________________________ 45, 200 Flood plains upstream from the junction of Bufi'alo Creek and Glen Creek were drilled by the US. Bureau of Mines in January and February 1952 (Griffith and Overstreet, 1953b, p. 11). Results of the drilling dis— closed that this part of the valley contains 2 million 238—813—67—16 225 cubic yards of alluvium in which there is 1,400 short tons of monazite, 20,000 short tons of garnet, 8,000 short tons of ilmenite, 2,000 short tons of sillimanite and kyanite, 1,000 short tons of rutile, and 200 short tons of zircon (Griflith and Overstreet, 1953b, p. 13). Monazite from this placer contains 6.55 percent of Th02 and 0.49 percent of U308 (Griffith and Over- street, 1953b, p. 16). LINCOLN COUNTY AND GASTON COUNTY The extreme northwestern part of Lincoln County is in the core of the monazite belt, but the rest of the western part of the county as far east as 0.5—2 miles west of the South Fork Catawba River is on the flank of the belt. From 6 to 12 miles east of the South Fork Catawba River, a band of monazite-bearing rocks 2—8 miles wide extends southward across the county (Over- street, 1962, fig. 2). Concentrates from alluvium in the western part of the county consist of dominant ilmenite, garnet, and monazite with accessory silli- manite, rutile, and zircon, and sparse magnetite and kyanite. In the eastern part of the county, monazite- bearing concentrates from alluvium consist of domi- nant magnetite, ilmenite, staurolite, and epidote and sparse and local kyanite., hornblende, garnet, and zir- con. Most concentrates from the western part of the county contain 5—20 percent of monazite, but those from the eastern part have 5 percent or less. Both monazite-bearing zones extend southward into Gaston County. The northwestern part of Gaston County is on the southeast flank of the monazite belt and just reaches into the core (Overstreet, 1962, fig. 2). Relations of the monazite-bearing zone in the eastern part of the county are imperfectly known; the zone seems to extend in the direction of the confluence of the South Fork Catawba River with the Catawba River. Commercial placers were developed along headwater tributaries to Bufialo Creek and Indian Creek in the northwestern part of Lincoln County, and by 1903 (table 58) the output of monazite in the county was a factor, although not a large one, in the production from North Carolina (Pratt, 1905, p. 46; 1907b, p. 122; Sterrett, 1908b, p. 274; Drane and Stuckey, 1925, p. 19; Ladoo, 1925, p. 394; Bryson, 1927, p. 15; Sant- myers, 1930, p. 10). The presence of detrital mona- zite in northwestern Gaston County seems to have been about as well known as the occurrences in Lin- coln County, but no records are available to show if monazite was mined. The Cherryville area, however, was cited as a monazite locality (Drane and Stuckey, 1925, p. 19), and the gold placers south of Crowders Mountain were long ago listed as containing monazite (Genth, 1891, p. 77—78, 86). What little formation is 226 available on these occurrences in Gaston County was summarized in the section on “Outlying localities in the Piedmont province between the western and east- ern monazite belts.” The only new information on monazite placers in Lincoln County was the appraisal of deposits along Indian Creek, Howards Creek, Pott Creek, and other tributaries to the South Fork Catawba River made in 1952 by A. M. White of the US. Geological Survey. He estimated that alluvium in these streams has an average tenor of 0.8 pound of monazite per cubic yard and that the resources are at least 51,500 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 711). According to A. M. White (written commun., 1954), the tenor of the sediments in the creeks is higher than the tenor of alluvium in the valley of the South Fork Catawba River north of Lincolnton, which is east of the monazite belt: Average tenor Resources (lb of monazite (short per cu yd) tons) Indian Creek __________________________ 1. O 16, 000 Howards Creek ________________________ 1. 3 13, 500 Pott Creek ____________________________ 1. 0 7, 000 South Fork Catawba River _____________ . 5 15, 000 Total ___________________________________ 51, 500 UNCONSOLIDATED SEDIMENTARY ROCKS IN THE COASTAL PLAIN PROVINCE The only report showing distribution of monazite in unconsolidated sediment of the Coastal Plain physi- ographic province in North Carolina was published by Dryden (1958), and this report is restricted to local— ities along the inner edge of the province. Dryden (1958, p. 398—400) reported that the results of miner- alogical and radiometric studies of 114 concentrates prepared from samples obtained at surface exposures showed that the Coastal Plain formations contained about the same suite of heavy minerals——mainly ilmen- its and leucoxene with zircon, rutile, monazite, staur- olite, kyanite, sillimanite, tourmaline, and spinel. Locally the formations have as much as 1.81 pounds of monazite per cubic yard, but they average only 0.16 pound per cubic yard. Of the 114 concentrates 14 were barren of monazite, and samples from localities northeast of Fayetteville, Cumberland County, were leaner in monazite than those from localities southwest of Fayetteville (Dryden, 1958, p. 421). Some of the samples having the highest tenor found by Dryden in the Southeastern States came from Cretaceous sedi- mentary rocks near the inner edge of the Coastal Plain between Fayetteville and the border between North Carolina and South Carolina. Lack of high-tenor samples to the northeast of Fayetteville suggested to Dryden that the eastern monazite belt contributed THE GEOLOGIC OCCURRENCE OF MONAZITE scant monazite to the Coastal Plain sediments in that area. Samples having a tenor as high as that of sam- ples from southwest of Fayetteville extend into South Carolina. The Coastal Plain sediments sampled by Dryden ranged in age from Cretaceous to Quaternary. Of the 85 samples taken from the Upper Cretaceous Tus- caloosa Formation, 9 lacked monazite. Two monazite- bearing samples and one monazite-free sample were taken from the Upper Cretaceous Black Creek Forma- tion. Four monazite-bearing samples were taken from the Yorktown Formation of Miocene age. Pleistocene deposits were the source of 22 samples of which 3 lacked monazite. Coastal Plain deposits in North Carolina have not been mined for monazite. The dis— tribution of the monazite-bearing samples is summar— ized from Dryden (1958, p. 398—400, pl. 19). TUSCALOOSA FORMATION The Tuscaloosa Formation is the oldest sedimentary unit of Cretaceous age exposed in North Carolina. It consists of variable tan, red, and gray arkosic sand and interbedded lenticular masses of clay (Stuckey and Conrad, 1958, p. 43—44). These sedimentary mate- rials were derived from the crystalline rocks of the Piedmont and Blue Ridge provinces. Monazite was found by Dryden in the Tuscaloosa formation at 76 localities in North Carolina (table 72). The most northerly of these occurrences are in Edge- combe County. From there the localities extend south- westward to the State line. With the exception of one sample in the Anderson Creek area of Harnett County and two samples south of Cameron in Moore County, the inferred tenor of all samples was considerably less than 1 pound of monazite per cubic yard. BLACK CREEK FORMATION The Upper Cretaceous Black Creek Formation con- sists of thin-bedded gray to light-yellow sand and dark-gray to black clay in North Carolina (Stuckey and Conrad, 1958, p. 44). The sand is fine to medium grained and generally crossbedded. Monazite was present in samples of sand taken by Dryden (1958, p. 400, pl. 19) at a locality south of Smithfield in Johnston County and at a locality near Purvis in Robeson County. The sand contained 0.16 and 0.14 pound of monazite per cubic yard. YOBKTOWN FORMATION The Yorktown Formation of late Miocene age in surface exposures in North Carolina consists mostly of clay, sand, and shell marl (Stuckey and Conrad, 1958, p. 45). Arenaceous to calcareous blue clay is the dominant component. Four samples of sand were NORTH CAROLINA found by Dryden (1958, p. 400, pl. 19) to be monazite bearing, but the amount of monazite was very small: 0.01 pound per cubic yard near Weldon, Northampton County; 0.03 pound per cubic yard near Rocky Mount, Edgecombe County; 0.07 pound per cubic yard north- east of Wilson, Wilson County; and, 0.03 pound per cubic yard south of Wilson, Wilson County. PLEISTOCENE DEPOSITS Nineteen monazite-bearing samples were collected by Dryden (1958, p. 400, pl. 19) from undifferentiated sediments of Pleistocene age in the western part of 227 the Coastal Plain in North Carolina. Eleven of these samples contained more than 0.25 pound of monazite per cubic yard. Inasmuch as only 24 of the 114 sam- ples taken by Dryden from the unconsolidated sedi- ments of that part of the Coastal Plain which is in North Carolina had that much monazite, the Pleisto- cene sediments seem to have somewhat more monazite than the older formations. The location and tenor of samples from Pleistocene deposits are given in table 73. STREAM DEPOSITS IN ms COASTAL PLAIN rnovmcn Alluvium in the valleys of streams in the Coastal TABLE 72.——Amount of monazite in the Tuscaloosa Formation in North Carolina [Modified from Dryden (1958, p. 398—399, pl. 19] Inferred Edgecombe County: (lb pin; yd) East of Rocky Mount ___________________________ 0. 03 . 05 Wilson County: Upper part of Black Creek _______________________ . 18 Johnston County: Near Pine Level ________________________________ . 02 South of Smithfield _____________________________ . 03 West of Smithfield ______________________________ . 05 ' . 08 West of Coats Crossroads ________________________ . 01 . 03 Vicinity of Benson ______________________________ . 01 . 12 . 01 . 02 Wayne County: Near Rose _____________________________________ . 02 . 05 Harnett County: Near Tunington ________________________________ . 02 . 03 Near Buies Creek _______________________________ . 05 . 4 Northeast of Olivia _____________________________ . 03 . 61 Northeast of Spout Springs ______________________ . 18 . 15 Near Anderson Creek ___________________________ . 23 . 15 . 08 . 03 . 1 1. 55 . 1 Cumberland County: Near Linden ___________________________________ . 1 . 15 Near Wade ____________________________________ . 02 . 13 West of Wade ___________________________________ . 08 . 08 Lee County: Sanford area ___________________________________ . 05 Inferred tenor Moore County: (lb per w 114) South of Cameron ______________________________ 1. 81 . 1 1. 13 Aberdeen area __________________________________ . 13 . 14 . 06 . 25 Hoke County: Northwest of Timberlake ________________________ . 05 . 1 Raeford area ___________________________________ . 02 . 25 . l . 1 Near Pine BluE ________________________________ . 2 Richmond County: Near Hoffman __________________________________ . 4 North of Hamlet _______________________________ . 08 . O9 . 1 . 15 East of Hamlet _________________________________ . 33 South of Hamlet ________________________________ . 04 . 43 Southwest of Hamlet ____________________________ . 48 . 05 West of Hamlet ________________________________ . 33 . 02 Scotland County: Near Silver Hill ________________________________ . 13 . 38 . 15 Near Old Hundred ______________________________ . 03 . 18 . 1 . 08 . 1 . 08 Northeast of Laurinburg _________________________ . 04 . 09 . 06 228 TABLE 73.—Amount of monazite in Pleistocene deposits in North Carolina [Modified from Dryden (1958, p. 400, pl. 19)] Inferred tenor (lb per Johnston County: w W) South of Smithfield _____________________________ 0. 09 Benson area .................................... . 08 Lee County: Sanford area ___________________________________ . 12 Moore County: Aberdeen area .................................. . 25 . 12 . 55 Richmond County: Near Hofl’man .................................. . 29 . 35 North of Hamlet ............................... . 38 . 42 . 65 East of Hamlet _________________________________ . 31 Anson County: East of Lilesville ________________________________ . 03 Lilesville _______________________________________ . 05 Scotland County: Near Old Hundred ______________________________ . 25 Southeast of Old Hundred _______________________ . 02 Near Silver Hill ________________________________ . 19 . 35 . 68 Plain physiographic province of North Carolina has not been mined for monazite, and very few data are available about the tenor of the fluvial sediments. There are no records of reserves. Dryden (1958) gave the only published record of monazite in fluvial de- posits in this area, but his report principally refers to surface samples of flood—plain silt or sand, which is ordinarily the lowest tenor material in the sequence of fluvial sediments. He found that concentrates from these materials contained as much as 6 percent of monazite but that the concentrate was small. Con- centrates from alluvium in streams rising within the Coastal Plain resemble in mineralogical composition concentrates from Coastal Plain formations. They have a restricted suite of heavy minerals dominated by ilmenite and leucoxene and also contain, in approx- imate order of abundance, zircon, rutile, monazite, stauroline, kyanite, sillimanite, tourmaline, and spinel. Concentrates from streams rising in the Piedmont were found by Dryden to contain these minerals plus epidote, garnet, and hornblende. Dryden sampled stream and flood—plain deposits at 23 localities in the western part of the Coastal Plain in North Carolina, and he found monazite in 21 of the samples (table 74). Samples having the greatest percentages of monazite are from localities south and southwest of Fayette- ville, Cumberland County, in the same general area THE GEOLOGIC OCCURRENCE OF MONAZITE where the Coastal Plain formations are richest in monazite. TABLE 74.—Amount of monazite in concentrates from stream deposits in the coastal plain of North Carolina [Modified from Dryden (1958, p. 401, pl. 19)] County Description Percent Northampton and Halifax- Roanoke River along the county border ....... (1).; 23 Hertford .................. Tributary to Meherrin River near Winton.-_. .3 Bertie ..................... Cashie River __________________________________ . 2 Bertie and Martin ________ Roanoke River along the county border _______ g Edgecombe ............... Tar River ..................................... 1:0 3.? 2. Wilson .................... Tolsnot Swamp Creek and Contentnea Creek 1.8 near Wilson. 1. 0 Wayne .................... Tributary to N ahunta Swamp Creek near . 7 Patetown. Neuse River near Goldsboro. __________ . 9 Johnston .................. Neuse River ___________________________ . 2 Black Creek _________________ 1. 0 Cumberland. . _ Tributary to Little River ...... __ 6. O Hoke ........... Tributary to Lumber River ................... . 9 Anson .......... Pee Dee River east of Lilesville _______________ 1.: Columbus ................. Lumber River near Boardman ________________ 2: 5 None of the through-going rivers in the Coastal Plain of North Carolina reach the monazite-rich parts of the monazite belt in the western Piedmont. For this reason the alluvium in their valleys seems to be a much poorer source for monazite than the alluvium in trunk streams in the Coastal Plain of South Carolina below Columbia. BEACH nnrosrrs Monazite was reported by Tyler (1934, p. 3—5, 7) as probably present in concentrates from 75 samples of beach sand along the North Carolina coast, but the identification was doubtful. Tyler recognized a per- sistent suite of heavy minerals consisting of ilmenite, staurolite, epidote, zircon, garnet, sillimanite, kyanite, hornblende, leucoxene, tourmaline, rutile, hypersthene, apatite, magnetite, monazite( ?), and andalusite. Staurolite was reported to be the most abundant non- opaque mineral, and the concentrates were said to make up less than 2 percent of the sand. W. H. Jones (1949a, p. 457) stated that monazite is widely dis- tributed in the sand of the North Carolina coast. He estimated that its average abundance is about 2 per- cent of the heavy minerals in a concentrate and that it varies from 0 to 6 percent of the concentrate (Jones, 1949a, p. 458). An airborne radioactivity survey of the part of the coast of North Carolina south of Cape Fear, Brunswick County, disclosed no unusual radio— activity in the beach sand (Meuschke and others, 1953). This fact indicates that concentrations of mona— zite in surface sand of the southwestern part of the North Carolina coast are much less than they are in South Carolina, Georgia, and Florida. Monazite has not been mined from the North Caro- lina beaches. OREGON OREGON Monazite has only been reported in fluvial and mar- ine black sands (Dixon, 1926, p. 77—79). A note by Treasher (1940, p. 73a) suggested that it may have been observed locally in gneiss and pegmatite, but detailed work has not disclosed it (Reed and Gilluly, 1932, p. 217). Most of the reported occurrences of detrital monazite in streams are situated in moderately large to very large drainage basins having complex geomorphic histories. The basins are underlain by diverse assemblages of rocks; therefore, unique assign- ment of sources of the monazite cannot be made. The same difficulty attaches to evaluating the probable sources of the detrital monazite on the Oregon coast. None of these placer deposits was a commercial source of monazite in 1962. STREAM DEPOSITS Black sands from streams in eastern Oregon con- tain small quantities of monazite, garnet, and zircon, but these sands are not sufficiently abundant to be economic sources for monazite (Moore, 1937, p. 7—8). The placers were reported by Moore to occur on pre- Cretaceous formations including siliceous argillites, greenstone, serpentine, other slightly to moderately metamorphosed rocks, gabbro, and granite. For the most part these kinds of rocks in other places in the world are generally barren of or only sparingly con- tain monazite. Monazite was observed by Day and Richards (1906b, p. 1206—1215) in black sand from gold placers in streams in northeastern Oregon at Weston, Umatilla County; Wallowa, Wallowa County; and Durkee, Baker County. Mostly the monazite constitutes less than 1 percent of the total heavy minerals in the con- 229 centrate, but at Weston it makes up about 2 percent of the material sampled (table 75). In central Oregon a small amount of monazite was found in a platinum- rich concentrate from Antone, Wheeler County. At the mouth of the Hood River and adjacent parts of the Columbia River in Wasco County, northwestern Oregon, fluvial sand contains abundant magnetite and olivine with which there is a very small quantity of monazite. A fraction of a pound of monazite per ton was found in black sands of various origin from the vicinity of Portland and Fulton, Multnomah County; Falls City, Polk County; Morrison and Elk Creek, Lincoln County; and Foster in Linn County. Small amounts of monazite are present in southwest- ern Oregon in sand from the South Fork Coquille River in Coos County, and in concentrates or sands from Wolf Creek, the Grants Pass area (Butler and Mitchell, 1916, p. 50—51), Kerby, Sucker Creek, and Coyote Creek in Josephine County. A trace of mona- zite is present in concentrates from Gold Hill and Birdseye Creek, Jackson County. The numerous sam- ples indicate that these Oregon streams are not favor- able sources for monazite. BEACH DEPOSITS Auriferous and platinum-bearing beach placers were discovered in Oregon in 1852 and were very profitably mined for a while thereafter (Pardee, 1934, p. 4—23). Considerable attention was given to the accessory min- erals in these placers about 1905. Industrial minerals like magnetite, chromite, and monazite were found to be present in concentrates and sands from the beaches, raised beaches, and adjacent parts of rivers (Day and Richards, 1906b, p. 1206-1215) . Monazite, however, is one of the least common minerals in the placers, and TABLE 75.—Mtneralog1§cal composition, in pounds per short ton, of natural sand and concentrates from streams in Oregon [Modified from Day and Richards (1906, p. 1206-1215). Symbols used: P, present; Tr., trace; .-, absent] Location Magne- Chro- Ilmenite Garnet Olivine Mona- Zircon Quartz Gold Platl- Others Source tite mite zite num 1. Weston, Umatilla County ........................ 981 688 -_ 113 36 46 122 12 P -- -- Undescrlbed. 2. Wallowa Wallowa County. _ 50 9 175 .. .7 ._ 630 P -. 610 Do. 3. Durkee, baker County .............. 72 2 720 s -_ Tr. 24 518 P .. 656 Do. 4. Do _____________________ _ 8 Tr. 32 -- -- Tr. 2 1,450 P .- 506 Do. 5. Antone, Wheeler County..- _ 1, 762 6 196 _- _. 2 -. 12 -. P 22 Concentrate. 6. Hood River, Wasco County _ 995 174 _- 221 287 5 16 -_ ._ -- -- Natural sand. 7. Do- ___- _ 22 3 -- 37 118 .4 .4 1,182 P ._ 634 Do. 8. Do- - 30 3 __ 9 129 . 5 1 1, 214 P .- 610 Do. 9. 0.- 135 19 -. 39 339 1 l 1, 048 P -_ 411 D. 10. Latourell Falls,Mu1tnomah County.. _ 52 312 _ 768 360 479 26 .- P .. -_ Undescribed. 11. Portland, Multnomah County ........ - 2 Tr. Tr. Tr. Tr. Tr Tr - __ .. 1,998 Do. 12. Fulton, Multnomah County ______ . 830 .- 909 _. 60 . 5 1 79 .- .. 118 Natural sand. 13. Falls City, Polk County ..... . 217 612 .- 739 852 .4 102 40 P _- 1 Undescribed. 14. Morrison, Lincoln County. - Tr. . __ 3 340 .3 .2 1,383 -_ -- 272 Natural sand. 15. ................... _ 1 1 __ 2 120 . 3 . 6 1, 526 -_ -- 346 Do. 16. Elk CZreek, Lincoln Conn - 2 8 -. 16 227 4 1 1,663 P -_ 75 Do. 17. ................... _ .1 2 __ 2 207 . 4 . 4 1, 720 P .- 67 Do. 18. FostDeii), Linn County _______ . 1,238 600 __ 71 ._ . 1 . 7 10 P P .. Do. 19. South Fork Coquille River, Coos County.. ___ 10 50 __ 15 _. .4 12 1, 757 -_ -_ -- Do. 20. Wolf Creek Josephine County ................... 392 90 _. 690 31 . 1 15 245 P P 533 Concentrate. 21. Kerby, Josephine County._-_ _ 751 24 _ 14 90 24 __ 1, 405 -_ -- 483 Natural sand. 22. Do _________________________________ 28 136 56 .. _- Tr 4 -. P P 28 Undescribed. 23. Sucker Creek, Josephine County__ _ 1,380 392 152 .. -- 12 10 2 P P 48 Concentrate. 24. Coyote Creek Josephine County . 336 1,456 -- -_ _. 46 28 184 P P 136 Do. 25. Gold Hill, Jackson County ..... _ 300 1,100 200 ._ __ Tr. Tr. .- ._ .. 400 Do. 26. Birdseye Creek, Jackson County . 8 .. ._ .. Tr. __ .. P -_ 200 Do. 230 THE GEOLOGIC OCCURRENCE OF MONAZITE it rarely reaches an abundance greater than 1 pound per short ton of concentrate (table 76). Of the 50 monazite—bearing samples described by Day and Rich- ards, those having the most monazite come from the extreme northwest corner of the State in Clatsop County around Astoria, Hammond, Fort Stevens, Clat- sop Spit, Clatsop, Clatsop Beach, Warrenton, Gear- hart, Gearhart Beach, Gearhart Park, Seaside, and Carnahan Station. Apparently this localization re— sults from the discharge of monazite at the coast by the Columbia River. Among these monazite-bearing samples the richest one, and the richest from Oregon exclusive of the sample reported from the vicinity of Latourell Falls, is a specimen of river bottom sand from the Columbia River near Astoria. Sand and concentrates from the central and southwest coast of Oregon around Yaquina Bay in Lincoln County, the Randolph district in Coos County, and Port Orford and Gold Beach in Curry County generally contain less than 0.1 pound of monazite per short ton. With the possible exception of deposits at the mouth of the Columbia River, the beaches do not contain enough monazite to be a commercial source for the mineral. PENNSYLVANIA Monazite in Pennsylvania was first reported in 1899 when J. G. Dailey discovered crystals of the mineral in gneiss of the Wissahickon( ?) Formation exposed at a quarry on the southeast side of Chester Creek near Morgan, Aston Township, Delaware County (S. H. Hamilton, 1899, p. 378). The monazite is in crystals as much as 0.25 inch across which are embedded in TABLE 76.———Mineralogical composition, in pounds per short ton, of natural sand and concentrates from beaches on the coast of Oregon [Modified from analyses by Day and Richards (1906b, p. 1206—1215) ; P, present] Location Source Magne- Chrorn— Garnet Olivine Mona- Zircon Quartz Gold Plati- Others me its zite num Clatsop County Astoria .................................. Natural sand ______________ 11 2 23 50 1 0. 6 1, 420 P __________ 38 d 6 2 Tr . 2 1, 333 632 6 l4 Tr. . 5 l, 413 540 3 271 52 131 . 1 639 P 888 Hammond 1 65 451 2 1 1, 065 P 252 7 18 314 1 47 1, 193 _______ 344 22 90 264 1 2 1, 073 P 247 145 428 184 l 9 43 P P ________ 24 30 663 1 . 8 1, 281 P P 35 171 174 .......... 8 6 335 P P 524 162 226 .......... 9 5 288 P P 483 173 149 218 4 6 362 P P 345 Fort Stevens 195 127 .......... 7 4 237 P P 365 3 126 2 5 1, 410 P P 440 1 9 241 3 4 1,319 422 4 83 243 1 2 1,368 277 5 11 563 3 1 1, 218 161 1 3 142 . 4 6 1, 562 272 Clatsop Snil’ 1 37 375 . 1 .6 1,235 ....... 335 . 6 11 . 2 . 9 993 P 892 83 137 466 . 6 4 597 P 173 2 . 5 . 3 1, 308 P 570 72 143 404 . 2 2 670 P 166 (318th 7 360 2 2 1, 616 P Tr. Clatsop Beach 43 137 .......... . 4 .6 54 Warmnfnn . 7 2 461 . 8 7 1, 455 66 1 1 203 . 1 . 2 1, 488 P 293 2 3 163 . 1 1 1, 451 P 362 5 7 353 1 8 888 P 725 Between Warrenton and Seaside ........ . 3 30 257 . 5 3 1, 644 _______ 66 Gearhart Beach . 5 29 11 . 1 .......... 1, 672 P 285 Gearhart Park 1 1 49 . 4 1 1,650 P 295 . 1 7 401 1 2 1, 555 P 30 Seaside. - _ 4 22 334 1 1 122 P 408 3 3 .......... 1 . 5 131 P 1,860 Carnaham 9ham“! .7 3 381 Tr. . 5 1, 609 P 1 2 155 229 Tr. . 1 1, 571 P 12 2 1 114 Tr. . l , 535 P 340 . 1 1 400 . 5 . 1 1, 460 P 136 1 22 210 . 5 . 3 1, 571 P 190 Lincoln County Yaquina Bay (in l. 122 128 516 Tr 78 256 P 330 _____ do 1---.-______-__--.-- 86 60 506 Tr 48 478 P 276 0003 County Randolph district ........................ Concentrate panned from 11 45 2 . 1 1 6 . 2 P P 1, 969 beach sand. _____ o__..________-___.-.-- 22 216 698 219 .2 46 794 P _.----.--- Natural coneentrate(?)-___ 20 583 741 __________ Tr. 45 240 368 Natural sand ______________ 11 202 168 221 Tr. 16 1, 378 __________________ Tr. Concentrate _______________ 48 1, 500 300 __________ Tr. 100 __________________ P ........ Curry County Port Orford .............................. 259 66 1, 104 276 . 1 3 289 1. Tr. . 6 4 6 Tr. l, 917 Gold Beach .............................. 584 82 205 67 . 5 5 524 1Contains ilmenlte, 57211) per short ton. SContains ilmenite, 546 lb per short ton. PENNSYLVANIA, RHODE ISLAND, AND SOUTH CAROLINA flesh-colored orthoclase associated with quartz, green muscovite, ilmenite, magnetite, hematite, hornblende, and tourmaline (Benge and Wherry, 1907, p. 5; Wherry, 1908, p. 70, 77). Feldspar quarries about 0.5 mile to the southwest of Boothwyn, Upper Chichester Township, Delaware County, expose pegmatite which was found in 1906 by Wherry (1908, p. 70—7 1, 77) to contain monazite, albite, andalusite, beryl, biotite, columbite, almandine, pyrite, muscovite, orthoclase, quartz, sphene, tourmaline, vermiculite, xenotime, and zircon (Benge and Wherry, 1907, p. 6—7 ; Benge, 1907, p. 45). The early reports of E. T. Wherry and Elmer Benge pointed out that primary monazite in Pennsylvania is exclusively confined to the areas of highly metamor- phosed schist and gneiss and that the monazite is espe— cially plentiful where pegmatite is present in the metamorphic rocks, as in southern Delaware County (Wherry, 1908, p. 60). In a later report Dryden and Dryden (1946, p. 92, 94) described monazite as an accessory mineral in 14 samples of schist from the Wissahickon Formation in southeastern Pennsylvania and northern Maryland. The presence of sillimanite, kyanite, and staurolite in these samples indicates that the monazite came from medium- to high—grade meta- morphic rocks. J affe, Gottfried, Waring, and Worth- ing (1959, p. 113) listed three monazite localities in muscovite schist of the Wissahickon Formation in the Philadelphia metropolitan area. The three monazite- bearing exposures are at Crum Creek south of Swath- more, Gulley Run south of West Manayunk, and Darby Creek in Clifton Heights. Alpha activity of about 3,000—4,000 1: particles per milligram per hour reported for this monazite indicates a probable Th02 content of 4—5 percent. The common presence of sillimanite, fibrolite, and almandine in the schists and gneisses around Philadelphia, as attested by the descriptions of Benge and Wherry (1907) in the Mineral Collector, suggests that a systematic study of the minor heavy accessory minerals would disclose many other mona- zite localities. The Keefer Sandstone of Silurian age exposed to the southeast and northeast of Masseyburg, Huntingdon County, was found by Landsberg and Klepper (1939a, p. 8; 1939b, p. 276) to contain abundant accessory zircon and tourmaline accompanied by rutile, hematite, chlorite, muscovite, and monazite. Xenotime but no monazite was observed in the Castanea Sandstone and Tuscarora Quartzite to the northwest of Masseyburg. Xenotime unaccompanied by monazite was also re- ported for heavy mineral suites from the Monongahela River at East Millsboro and Dunkard Creek in south- western Pennsylvania (King, 1932, p. 487). The 231 presence of xenotime, however, suggests that monazite may also be present in small amounts (Martens, 1932, p. 73, 79—80) . RHODE ISLAND CRYSTALLINE ROCKS As early as 1891 the granites exposed around Westerly and Narragansett Pier, Washington County, were shown by Derby (1891a, p. 205; Am. Naturalist, 1892) to be monazite bearing. The rock at Westerly was said to be especially rich in monazite. Later reports by Kemp (1899, p. 368), Loughlin (1912, p. 127) and Quinn, Jaife, Smith, and Waring (1957 , p. 549) repeated Derby’s observation and extended the known presence of monazite in the rocks of the Narra- gansett Bay area to scattered occurrences in pegmatite dikes that cut across the granite at Westerly. Mona- zite was reported to occur in granite exposed at the Redstone quarry near Westerly in the Ashaway quad- rangle (J alfe and others, 1959, p. 102) . At this locality the monazite is accompanied by bastnaesite and uranoan thorianite, but allanite is absent. The abun- dances of the accessory minerals in the granite at the Redstone quarry were estimated by Smith and Cisney (1956, p. 80) as percentages of the whole rock: Percent Magnetite and ilmenite ______________________ 0 . 13 Apatite ____________________________________ . 05 Bastnaesite ________________________________ . 02 Pyrite _____________________________________ . 005 Monazite __________________________________ . 002 Sphene ____________________________________ . 001 Zircon _____________________________________ . 001 Uranoan thorianite __________________________ .001 Although allanite was not noted at Redstone quarry, it accompanies monazite in the granite exposed at Narragansett Pier. This granite was said to be equiv- alent to that in the Redstone quarry near Westerly (Quinn and others, 1957, p. 549). A dike of granodioritic phase of the Westerly Granite exposed at Bradford, Washington County, contains minor accessory monazite with common accessory allanite, apatite, magnetite, sphene, and zircon (Hall and Eckelmann, 1961, p. 628). SEDIMENTARY nnrosrrs Beach sand on the south shore of Block Island, New- port County, in the Vicinity of New Shoreham was reported to contain accessory detrital monazite, silli- manite, and zircon (Fisher and Doll, 1927, p. 433). Monazite is present in sedimentary deposits on the Continental Shelf in the Atlantic from Block Island to the loo-fathom line (Alexander, A. E., 1934, p. 13) . SOUTH CAROLINA Monazite was first found in South Carolina nearly 50 years after its discovery around 1849 in North Caro- 232 lina. The earliest references to monazite listed by Petty (1950, p. 7—61) in his bibliography of geology of the State were reports by Mezger in 1896 and Nitze in 1897 on monazite placers of the Carolinas, but an even earlier account of monazite from South Carolina is known (Mezger, 1895). By 1900, placers in the western Piedmont in South Carolina were listed in the international literature as commercial sources for monazite (Nordenskiold, 1900, p. 217), although the first recorded output was 44 short tons in 1903 (table 30). Between 1903 and 1910, the last year of record, the State produced 557 short tons of monazite. By 1917, when the monazite placer industry came to a close in the Carolinas, the distribution of monazite in South Carolina was still not well known (Sloan, 1908, p. 129—142; Atkinson, 1910, p. 77; Pratt, 1916, pl. 1), and it was not until interest in the mineral revived in the 1940’s and 1950’s that knowledge of its regional dis- tribution became better known than in the descriptions given by Sloan and in the map published by Pratt. Commercial production of monazite from fluvial placers in South Carolina was resumed in 1955 when Marine Minerals, Inc., commenced dredging at Horse Creek, Aiken County. This operation ceased in 1959. Similar placers seem to be present in several other streams in the same general area, and large low-tenor deposits of monazite have been reported on coastal islands south west of the mouth of the Santee River. CRYSTALLINE ROCKS IN THE WESTERN MONAZITE BELT IN THE PIEDMONT PROVINCE The main area in which monazite-bearing crystalline rocks are found in South Carolina is the zone of plutonic gneisses, schists, and granitic rocks in the western part of the Piedmont physiographic province to which Mertie (1953, p. 15) gave the name western monazite belt. As defined by Mertie the western monazite belt in South Carolina is only a segment of a much longer zone which reaches from Alabama to Virginia. Prior to Mertie’s work a monazite belt was recognized in the western Piedmont of North and South Carolina, but no extension of the belt was known southwest of Anderson County (Sloan, 1908, p. 129; Pratt, 1916, pl. 1). Thus, most of the South Carolina segment of the western monazite belt was known to Sloan (1908, p. 129), who called it the great economic monazite belt of the Anderson-Spartanburg zone and to Pratt (1916, pl. 1) who called it the monazite belt. The rocks in the western monazite belt in South Caro- lina are an extension of sillimanite-almandine sub- facies schists and gneisses and isofacial sillimanite-free biotitic rocks present in the belt in North Carolina. Early interpretations ascribe the origin and occur- rence of monazite in the crystalline rocks of the west- THE GEOLOGIC OCCURRENCE OF MONAZITE ern belt in South Carolina to metasomatic processes (Sloan, 1904, p. 140; 1908, p. 130). Later interpreta- tions emphasize the dominance of either relict detrital grains (Mertie, 1953, p. 29—30) or regional metamor- phism (Overstreet, Cuppels, and White, 1956) in the occurrence and distribution of the monazite. These concepts are reviewed under the section on “North Carolina” because more work has been done on mona- zite in that State than in South Carolina. The known occurrences of monazite in crystalline rocks in the western belt in South Carolina are prin- cipally ones described by Mertie (1953). Few other descriptions have been published, but the information available will be summarized. In a later section this information is augmented by descriptions of the dis- tribution of monazite placers in streams in the western monazite belt. Micaceous schists and feldspathic rocks to the north- west of the Kings Mountain belt in Cherokee County were reported by Sloan (1904, p. 137) to be monazite bearing, but none was known to have mineable concen- trations of monazite. A light-gray medium-grained granitic rock exposed in northeastern Cherokee County, northern Spartan- burg County, and central Greenville County was said by Griflitts and Olson (1953b, p. 317) to contain accessory monazite. The rock consists of quartz, microcline, orthoclase, oligoclase, biotite, and muscovite with accessory monazite, apatite, and zircon. Monazite-bearing rocks were observed at five places in Cherokee County by Mertie (1953, p. 19). These rocks include granite, schist, and pegmatite at three localities near Gafl'ney; pegmatite exposed 0.9 mile southwest of Grassy Pond; and pegmatite at an exposure 1 mile south of the Cowpens Battleground Monument. In Spartanburg County pegmatite at a locality 4 miles southeast of Chesnee and granite at exposures 0.3 mile southwest of Mayo, on the north edge of Spartan- burg, and 1.9 miles northeast of Reidville have acces- sory monazite (Mertie, 1953, p. 19—20). Greenville County was the source of nine monazite— bearing samples of crystalline rocks collected by Mertie (1953, p. 19—20). Gneissic granite at a locality 2.2 miles northeast of Moonville contains accessory mona- zite. Aplite, pegmatite, and pegmatized gneiss in the vicinity of Conestee have monazite as an accessory mineral as does granite exposed near Piedmont and at two localities near Woodville. Pegmatized gneiss out- cropping 3.75 miles south of Batesville and granite gneiss 3.5 miles east-southeast of Simpsonville are also monazite bearing. SOUTH CAROLINA Contorted biotite granite gneiss in a quarry 2.4 miles northeast of Liberty, Pickens County, was re- ported by Alfred and Schroeder (1958, p. 2) to be monazite bearing. According to Alfred and Schroeder, the rock is a dome—shaped intrusive mass of medium— grained layered gneiss in which light-colored bands of feldspar and quartz alternate with thinner and less continuous dark-colored bands rich in biotite. Highly contorted coarse—banded gneiss at the east face of the quarry was said to have more quartz and feldspar and less biotite and accessory minerals than uncontorted close-banded gneiss at the north face (Alfred and Schroeder, 1958, p. 2): Percent East face North face Quartz _________________________________ 20-25 15—20 Microcline and albite _____________________ 50—60 40—50 Biotite plus some muscovite _______________ 10-15 15—20 Zircon, monazite, garnet, titanite, apatite, pyrite ________________________________ 2—3 3—5 Monazite is not present in every sample of gneiss from the Liberty area, and what was reported as mona- zite by Alfred and Schroeder may have been epidote; however, nearby epidote-rich low—grade monazite placers indicate the local presence of accessory mona- zite. J. B. Mertie, Jr. (written commun., 1959) stated that a concentrate of accessory minerals panned from a large sample of weathered rock taken very close to the quarry consisted of 14.3 percent magnetite, 63.8 percent ilmenite, 1001- percent zircon and epidote, garnet, apatite, sphene, and quartz. Monazite was not present in the concentrate. Mertie also disagreed with Alfred and Schroeder about the composition of the feldspar and the possible origin of the gneiss. He noted that the plagioclase is oligoclase and not albite. In Mertie’s opinion the rock is probably a paragneiss instead of an orthogneiss. The probable metasedi- mentary origin of the gneiss is also supported by H. S. Johnson, Jr. (written commun., 1959). Granite gneiss and granite at two localities near Honea Path in Anderson County contain accessory monazite (Mertie, 1953, p. 20). Monazite in placers in this area was known at least as early as 1908 (Sloan, 1908, p. 129). In Laurens County, monazite was found by Mertie (1953, p. 20) in granite gneiss near the Reedy River east of Princeton and in muscovite granite gneiss at the west edge of Gray Court. OCCURRENCES IN THE CENTRAL PIEDMONT PROVINCE Detrital monazite in stream sediments was reported at several localities in York County and Union County in the central part of the Piedmont physiographic province in South Carolina. The occurrences are 233 between the western and eastern monazite belts as described by Mertie( 1953, pl. 1), and they seem to be a southwestward extension of a small group of mona- zite localities reported from eastern Gaston County and Mecklenburg County in North Carolina. Together they form a discontinuous but more or less linear and narrow zone that may be related to the distribu- tion of the Yorkville Quartz Monzonite (Overstreet and Bell, 1962, map). This zone has not been given a name, although as early as 1908 Sloan (1908, p. 129) regarded the monazite in York County to be part of a subordinate belt parallel to the main belt of monazite- bearing rocks to the west. Very little is known about the source rocks from which this monazite came, and the Yorkville Quartz Monzonite has not been reported to contain accessory monazite. In York County monazite has been found as detrital grains in Crowders Creek and its tributaries, and on the north branch of Allison Creek 7 miles northeast of the city of York (Sloan, 1904, p. 140; 1908, p. 129, 141). The Allison Creek deposit, known as the Jessie C. McKinzie placer, was described as being lean in monazite, and the little monazite present was said to be rather localized. Deposits of monazite sand were reported in Union County, but the location and size have not been described (J. G. Parker, written commun., 1962). CRYSTALLINE ROCKS IN THE EASTERN MONAZITE BELT IN THE PIEDMONT PROVINCE As early as 1891 concentrates from granite around Winnsboro in Fairfield County and Newberry in New- berry County had been examined for monazite by Derby (1891a, p. 206). It is not certain from Derby’s description that he identified monazite in these rocks; therefore, credit for the discovery belongs to Mertie, who in 1947 found that crystalline rocks in the eastern part of the Piedmont physiographic province in South Carolina were locally monazite bearing. The occur- rences were regarded as a possible extension of the eastern monazite belt he recognized in North Carolina and Virginia (Mertie, 1953, pl. 1). Subsequently, crystalline rocks elsewhere in the eastern Piedmont were found by other workers to contain accessory monazite. By 1962, sporadic occurrences of monazite were known from Fairfield County southwestward nearly to the Georgia line. In part the monazite- bearing crystalline rocks are overlapped by the uncon- solidated sediments of the Coastal Plain and are exposed in valleys near the inner edge of the Coastal Plain. The geographic distribution and geologic relations of crystalline rocks with accessory monazite are rather poorly known in the eastern Piedmont. The rocks 234 seem to occupy several subparallel zones instead of one belt, or, possibly, the belt can be interpreted to include all zones. The monazite-bearing rocks occur in areas where the regional metamorphism reaches the kyanite-staurolite subfacies. The eastern belt is sepa— rated from the western belt by albite-epidote-amphi- bolite facies and lower grade rocks in the central Pied- mont (Overstreet, Overstreet, and Bell, 1960; Over- street and Bell, 1962). The eastern belt is of lower average metamorphic grade than the western belt, and it seems to contain more postkinematic granitic intru- sive rocks with accessory monazite than the western belt. Possibly the subparallel zones where monazite is found in the eastern belt represent local meta- morphic highs in an otherwise monazite-free area. The localities where monazite was first discovered in the eastern belt are the quarries southwest and west of Winnsboro in Fairfield County. Mertie found mona- zite in four samples of postkinematic granite exposed at Rion and Anderson Quarry southwest of Winnsboro and in one sample of granite from a quarry at Blairs to the west of Winnsboro (Mertie, 1953, p. 20). The granite mass at Winnsboro was later shown to be a teardrop-shaped diapiric postkinematic pluton of probable late Paleozoic age that intruded kyanite- staurolite subfacies schists (Overstreet, Overstreet, and Bell, 1960; Overstreet and Bell, 1962; Overstreet, Bell and others, 1961, p. B105). The granite is much younger than the main monazite-bearing granitic rocks in the western belt, which are probably Ordovician in age. The monazite-bearing granite at Blairs may also be late Paleozoic in age. As yet the age of maxi- mum metamorphism of the schists and gneisses in Fairfield County is not known, but it may be only a little older than the diapiric pluton and considerably younger than the Ordovician metamorphic climax recorded in the western belt. The eastern monazite belt is probably younger than the western belt in the Piedmont and is certainly younger than the belt in the Blue Ridge. Genetic implications following from the probability that the monazite belts are progressively younger from west to east have been discussed in the section on North Carolina. Accessory monazite was reported by J. F. McCauley (oral commun., 1959) in thin sections of granite and gneiss from central and eastern Newberry County to the west—southwest of the occurrences in Fairfield County. Inasmuch as monazite is not usually observed in thin sections of monazite—bearing rocks from the Southeastern States because it is ordinarily extremely sparse, these observations suggest that some rocks in Newberry County may have accessory monazite in more than the usual amount. THE GEOLOGIC OCCURRENCE OF MONAZITE Deep red soil on the campus of the University of South Carolina in Columbia, Richland County, was reported to contain sparse monazite (Perry, 1957, p. 5), but it is not certain if the monazite is residual from underlying crystalline rocks or if it was brought in along ancient water courses from the northwest. Radioactive granite underlying the Tuscaloosa For- mation in the valley of Long Creek, a tributary to Twelvemile Creek in Lexington County, is probably monazite bearing (Schmidt, 1962, p. 36). Similar radioactive granite exposed in the valley of McTier Creek in northern Aiken County contains monazite (H. S. Johnson, Jr., oral commun., 1959; Schmidt, 1962, p. 35). Radioactive granite in the vicinity of Graniteville, Aiken County, is probably monazite bearing (Schmidt, 1962, p. 36). FLUVIAL PLACERS IN THE WESTERN PIEDMONT PROVINCE Small fluvial placers formed on monazite-bearing crystalline rocks in the western Piedmont physio- graphic province of South Carolina were the source of 557 short tons of monazite produced by hand methods of mining between 1903 and 1910 (table 30). Most of the mining was done in Cherokee County north and west of Gaffney, Spartanburg County near the settle- ment of Cowpens, Greenville County in the vicinity of Mauldin and Piedmont, and Anderson County at Pelzer (Pratt, 1903, p. 180481; 1906, p. 1314; 1907a, p. 38; Eng. and Mining Jour., 1906b; Bohm, 1906; Graton, 1906, p. 116—117; Sloan, 1908, p. 131; Ladoo, 1925, p. 396; Santmyers, 1930, p. 10). The mining of South Carolina placers ceased in 1910 after the mona— zite discovered in India was entered into world com- merce at a much lower price than could be met by South Carolina mines (Schaller, 1919, p. 156). In 1906 monazite placers were discovered in parts of Pickens, Oconee, and Laurens Counties, but none seems to have been mined before the industry closed (Pratt, 1907b, p. 109; Pratt and Sterrett, 1908a, p. 315; Sterrett, 1908b, p. 274). Names and locations of 39 individual placers in the western monazite belt in South Carolina were listed by Sloan (1908, p. 132— 142) near the close of monazite mining: Cherokee County 1. W. H. Weber placer on Thicketty Creek 2.5 miles northeast of the settlement of Cowpens in Spartanburg County. 2. J. Caldwell and Romeo Martin mine on Thicketty Creek 2.4 miles northeast of Cowpens. 3. James Oglesby placer on Thicketty Creek 1 mile northeast of Cowpens. 4. R. Potter placer on east side of Thicketty Creek north of Thicketty. 5. Placer along Littlejohn Creek on the property of Joe Husky, J. C. Blanton, J. C. Painter, and T. T. McGraw between 3 and 4 miles northwest of Gaflney. SOUTH CAROLINA 6. Frank Leadford placer on Ashworth Creek. 7. Placer on the Serratt property and J. B. J ones land along the east bank of Cherokee Creek 3.5 miles north of Gatfney 8. J. J. Magnus and J. M. Swaford placer on the east bank of Cherokee Creek 3.5 miles north of Gaffney. 9. Lemon mine on a northwest tributary to Cherokee Creek 3.3 miles north of Gafiney. Spartanburg County 10. Paine’s placer 3 miles south of Greer. 11. A tributary to the Pacolet River 2.5 miles east of Spartanburg. 12. J. J. C. Ezell placer 8 miles north of Cowpens. 13. Martin’s placer on a tributary to the Pacolet River 5 miles northwest of Cowpens. 14. Conway Black placer 2.5 miles north of Converse. 15. Charles Petty placer 4 miles northwest of Cowpens. 16. J. Dewberry placer 4 miles northwest of Cowpens. 17. W. E. Bryant mine on Becks Branch tributary to the Pacolet River 0.5 mile northwest of Cowpens. 18. Placer on the property of Charles Sims, Rufe Tanner, S. B. Wilkins, and T. E. Wilkins along Becks Branch 0.5 mile west of Cowpens. 19. Robins placer 3 miles north of Cowpens. 20. Martin mine on Allen Creek 8 miles north of Pacolet. 21. J. M. Hays placer on a branch of Allen Creek 8 miles north of Pacolet. V. Welchel mine on Floods Branch, a tributary to Allen Creek, 0.7 mile north of Cowpens. Duval mine on Island Creek, a fork of Allen Creek. 22. J. 23. J. Greenville County 24. J. D. Green placer on Five Mile Branch tributary to Gilder Creek 6 miles east of Greenville and immediately south of Roper Mountain. Downstream along Five Mile Branch and Gilder Creek, placer monazite is present on property of Jackson Brown, Thomas Bramlet, Louis Rector, A. Rothschild, and Wyatt Smith. 25. Alexander brothers’ placer 4 miles west of Mauldin. 26. Berry Waldrop placer on Baker Creek 5.5 miles south of Piedmont. 27. Dave Terry placer 6 miles south of Piedmont. 28. J. S. Hill, Jr., placer 0.4 mile west of Mauldin. 29. Thomas Fowler placer on Maple Creek 1 mile south of Mauldin. 30. A. White placer 1 mile south of Mauldin. 31. Molly Garrett placer on Maple Creek 1.2 miles south of Mauldin. 32. Brooks mine on Maple Creek 1.4 miles southwest of Mauldin. 33. J. R. Bramlet placer 1.4 miles southwest of Mauldin. 34. Wyatt Smith placer on Gilder Creek 1.2 miles northeast of Mauldin. 35. W. M. Burdin mine 3 miles southeast of Mauldin. 36. F. A. Alston mine 2.5 miles southeast of Mauldin. Anderson County 37. Robert Simpson placer 3.5 miles north-northwest of Pelzer. 38. J. G. S. Smalls placer 1 mile south of Pelzer. 39. Charles Wideman placer 1 mile south of Pelzer. Several of these deposits were cited in earlier reports than Sloan’s, and they have been mentioned time and again in later discussion, with the result that the appar— ent importance of individual small placers has been magnified out of regional perspective. Even the Lemon 235 mine, called one of the most continuous and prolific producers of monazite in South Carolina, was only a small operation situated on a little tributary to Chero- kee Creek (Sloan, 1908, p. 140). As early reports show, the mined placers were small and shallow, with mona- zite—bearing gravel generally less than 1 foot thick (Graton, 1906, p. 117). The thickness of overburden that could be profitably removed during mining varied with the richness of the gravel, but no worked deposit was more than 10 feet deep, a few hundred feet wide, and a mile long (Sterrett, 1908b, p. 279—280). The main valleys of large streams in the monazite belt were not mined. In addition to the deposits listed above the early literature called attention to monazite placers on a tributary to the Saluda River 1 mile east of Donalds in Abbeville County and on Walnut Creek near Ware Shoals in Greenwood County (Sloan, 1908, p. 129). Monazite from South Carolina placers was said by Sloan (p. 131) to contain 3—7.25 percent of T1102, but only a single analysis was recorded in the early litera- ture. It was made in 1908 by Chernik and has since been republished by Houk (1946, p. 3): Percent 06203 ____________________________________ 34. 50 (La, Di, Y)203 _____________________________ 28.80 Th0; _____________________________________ 7. 00 P205 _____________________________________ 26. 00 Sl02 ______________________________________ 2. 00 TiOz _____________________________________ . 90 ZI‘Oz _____________________________________ . 70 CaO _____________________________________ . 70 Total _______________________________ 100. 60 For 30 years after the close of the monazite industry in South Carolina in 1910, no studies of fluvial monazite placers were undertaken. In 1943 the Regional Prod- ucts Research Division of the Tennessee Valley Au- thority examined stream placers in Cherokee County to learn if these sources could be substituted for foreign supplies of monazite (McDaniel, 1943, p. unnumbered). , Special circumstances of unusually high price and demand would be needed to revive the industry. If such conditions were met, the Carolina deposits would probably be sufficient to supply moderate domestic needs. During 1945 Mertie (1953, p. 9, 12) panned concen- trates from gravel in small streams at 11 localities in Cherokee County, 1 in Spartanburg County, and 4 in Greenville County. The amount of monazite in the riffle gravel was estimated, and monazite separated from the concentrates was analyzed for ThOz and U303 (table 77) The range and average amounts of monazite in the riffle gravel confirmed earlier reports of the tenor of 236 monazite-bearing gravel in South Carolina; for exam- ple, Sloan (1908, p. 131) had reported that “with a full supply of water a placer deposit which will afford a pound of monazite from a barrow—load of gravel is considered a ‘good proposition.’ ” If the barrow-load were assumed to be about 2.5 cubic feet, then the gravel would have contained about 10 pounds of monazite to the cubic yard. The tenor of the sediment from grass roots to bedrock was, of course, much less, but then only gravel was mined and low-tenor overburden was discarded. TABLE 77.—Thorium and rare-earth composition of monazite in rifle gravel from Cherokee, Spartanburg, and Greenville Counties, 8.0. [Modified from Mertle (1953, p. 9-10, 12). Chemical analyses for Th0; and U203 by F. S. Grimaldi, U.S. Geol. Survey] Tenor of Composition gravel of monazite Sample Location (1b of (percent) monazite per cu yd) Th0: U308 Cherokee County: Cherokee Creek _________________ l. 4 5. 87 0.49 _________ do__.-_--_.__.._-___.._..___ 1.8 6.45 .23 .......... do_____-._...._.___ 3.5 6.21 .22 Little Cherokee Creek. _ 3.1 4. 90 . 45 Beaverdarn Creek ...... ___ 1.2 5. 91 . 22 Joe Welchell Creek ______________ 3. 6 6. 44 . 24 Floyd Branch, Island Creek. .. . 3. l 4. 95 . 55 Cudds Creek ____________________ 7. 9 4. 84 . 58 Bill Martin Creek ______ __- 6. 4 4. 91 .58 Little Thicketty Creek .......... 3. 9 6. 59 . 19 Macedonia Creek ............... 7. 3 6. 76 . 18 Spartanburg County: Double Branch ................. 1. 7 5.47 . 36 Greenville County: Gilder Creek..- 3.8 5. 56 . 55 Reedy Creek 3. 8 5.05 . 47 Hufi Creek ..... 8. 6 5.08 .24 41. 9 4. 85 32 6. 4 5. 61 36 A concentrate from monazite-bearing sand was col- lected by A. S. Furcron from the South Carolina side of the Tugaloo River in Oconee County below the mouth of the Chauga River (Zodac, 1953, p. 58). The concentrate contained monazite, zircon, garnet, rutile, epidote, and magnetite. A regional appraisal of fluvial placers downstream from the former sites of mining in the western Pied- mont was undertaken by the U.S. Geological Survey in 1951 for the Atomic Energy Commission as a result of Mertie’s investigations. Selected valleys were drilled by the U.S. Bureau of Mines. Fieldwork was com- pleted in 1954. Results of these investigations showed that large valleys in the western monazite belt in South Carolina contain at least 367,000 short tons of monazite in sediments having an average tenor of 0.6 pound of monazite per cubic yard from the top of the flood plain to bedrock (Overstreet, Theobald, and Whitlow, 1959, p. 710—712). The work also showed that the THE GEOLOGIC OCCURRENCE OF MONAZITE richest deposits are in streams that flow on a zone of sillimanite schists and gneisses which form the core of the monazite belt (Overstreet, Cuppels, and White, 1956; Overstreet, 1962, p. 158—161). Summaries of this exploration follow and are given in geographic order by county from northeast to southwest. CHEROKEE COUNTY The east edge of the monazite belt passes southwest- ward across Cherokee County about 3 miles east of Gafl'ney dividing the county into a monazite-bearing northwest half and a monazite-free southeast half (Keith and Sterrett, 1931, map; Mertie, 1953, pl. 1; Overstreet, 1962, fig. 2). The northwest quarter of the county is in the core of the monazite belt, and from a point about 3 miles northwest of Gafi'ney to the extreme northwest corner of the county, concentrates from stream sediments contain 15—50 percent of mona- zite, with most concentrates having about 20—30 per- cent. Rutile, sillimanite, almandine, and ilmenite are the principal associated minerals. Along the east edge of the belt near Gafl'ney and east of the belt in monazite-free parts of the county, staurolite, kyanite, magnetite, and amphibole dominate the concentrate (Overstreet and Griflitts, 1955, pl. 1). The monazite-bearing streams in the county are tributaries to the Broad River. Along the north edge of the county several short but monazite—rich streams rise and flow northward to enter the Broad River in Cleveland County and Rutherford County, NC. Sev- eral of these short north-flowing tributaries to the Broad River were former sites of monazite placer mines. Near the State line the trend of the valley of the Broad River swings from east to south, and short tributaries in the belt north of Gafl'ney flow east to the river. One major south-flowing monazite-bearing tributary enters the Broad River from the north in northeastern Cherokee County. This is Buffalo Creek. Except for the short north-flowing and east-flowing creeks, the principal drainage in the northwest half of Cherokee County is the basin of Cherokee Creek and that of Thicketty Creek. Both these streams enter the Broad River from the west. The resources in monazite in fluvial deposits along the short north- flowing and east-flowing tributaries to the Broad River, including their parts in North Carolina, the Broad River itself, including the east—flowing segment in North Carolina from a point near the northwest corner of Cherokee County to the State line north of Gafl'ney and the south-flowing segment from the State line to a point about a mile upstream from the mouth SOUTH CAROLINA of Cherokee Creek, and the drainage basins of Chero- kee and Thicketty Creek were estimated to be at least 70,000 short tons (Overstreet, Theobald, and Whitlow, 1959, p. 711). The resources of monazite in the main valley of the Broad River from the point in North Carolina north of the northwest corner of Cherokee County to the point in South Carolina upstream from Cherokee Creek was conservatively estimated to be at least 17,000 short tons in 90 million cubic yards of alluvium (Over- street, Theobald, and Whitlow, 1959, p. 711). The reserves of monazite in the valley of the Broad River at the mouth of Bufl'alo Creek were evaluated by churn drilling and estimated to be 3,500 short tons (Hansen and Theobald, 1955, p. 5). Above its junc— tion with Buffalo Creek, the Broad River emerges at the east side of the monazite belt. Its many tributaries in the belt drain about 1,400 square miles underlain by weathered monazite-bearing crystalline rocks and give the river the maximum input of monazite of any trunk stream crossing the western belt. Buffalo Creek rises in northwestern Lincoln County, N.C., and flows southward for 43 miles to join the Broad River in northeastern Cherokee County, SC. In the lower half of Buffalo Creek, only its western tributaries reach monazite-bearing rocks, but the upper half of the creek is in or along the east edge of the monazite belt. The flood plain in the valley of the Broad River at the mouth of Buffalo Creek was drilled by the U .8. Bureau of Mines in November 1952 to determine the tenor and composition of sediments in the valley of a trunk stream crossing the belt. Results of this work in South Carolina are summarized in the following dis- cussion; a review of Buffalo Creek as a whole was given in the section on North Carolina. Eight churn-drill holes were sunk in the flood plain on the Broad River, and two were sunk in the flood plain at the lower end of Buffalo Creek. The alluvium was found to range in depth from 13 feet on Buffalo Creek to 26.5 feet on the Broad River. The combined area of the deposit was 2,760,000 square yards, and the volume of alluvium was estimated to be 19.7 million cubic yards. Most of the alluvium was clay, silt, and fine sand, and its tenor in heavy minerals and monazite was found to be low: 4.86—20.51 pounds of black sand per cubic yard, the average being 11.8 pounds, and 0.16—0.62 pound of monazite per cubic yard, the average being 0.36 pound (Hansen and Theobald, 1955, p. 21, 24—25). The mineralogical composition of a concentrate from a composite sample from one drill hole in the flood plain of the Broad River was 237 reported to be (Hansen and Theobald, 1955, p. 18) as follows: Percent Percent of concentrate of concentrate Ilmenite _____________ 40 Rutile _______________ 3. 0 Epidote ______________ 13 Kyanite and silli- Zircon _______________ 13 manite _____________ 2. O Garnet _______________ 10 Magnetite ____________ 1. 5 Quartz _______________ 7 Staurolite ____________ 1 :I: Amphibole ___________ 6 Tourmaline ___________ 1 i Monazite _____________ 3. 3 Xenotime ____________ Trace Unless a part of the valley of this trunk stream could be found that is filled with deposits containing far more coarse-grained sediment than was found on this part of the Broad River, workable monazite placers cannot be expected. Monazite from the flood plain on the Broad River at the mouth of Buffalo Creek contains 4.64 percent of Th02 and 0.58 percent of U303 (Hansen and Theobald, 1955, p. 24). The main short north—flowing tributaries that rise in northern Cherokee County, S.C., and enter the Broad River in Rutherford County and Cleveland County, N.C., are, from west to east, Horse Creek, Suck Creek, Ashworth Creek, and Camp Creek. The tenor and resources of monazite along these streams were estimated by P. K. Theobald, Jr. (written commun., 1954) of the U.S. Geological Survey: Tenor (lb of menazite per Resources cu yd) (short tons) Horse Creek __________________________ 2.3 4, 100 Suck Creek ___________________________ 1.3 3, 300 Ashworth Creek _______________________ 3.1 3, 900 Camp Creek __________________________ .1 40 Ashworth Creek was worked for monazite at the Frank Leadford placer (as noted on p. 235), and the south- eastern headwaters of Camp Creek were also mined (Keith and Sterrett, 1931, map). Ross Creek and its main tributary, Sarratt Creek, are the principal eastward-flowing monazite-bearing streams to enter the Broad River in Cherokee County. Parts of the headwaters of both streams were formerly mined for monazite (Keith and Sterrett, 1931, map). The valleys of the two creeks were estimated by P. K. Theobald, Jr. (written commun., 1954) to con— tain at least 3,800 short tons of monazite in alluvium having an average tenor of 1.4 pounds of monazite per cubic yard. Cherokee Creek is mostly underlain by granitic and high-rank metamorphic rocks in the central and east- ern parts of the monazite belt (P. K. Theobald, Jr., written commun., 1954). Only the lower 1.5—2 miles of its course is east of the monazite belt. Many of its headwater tributaries, particularly branches in the 238 vicinity of Grassy Pond, were formerly mined for monazite (p. 235) (Keith and Sterrett, 1931, map). Resources of monazite in the stream as a whole were estimated by P. K. Theobald, Jr. (written commun, 1954) to be 9,000 short tons in sediments having an average tenor of 1.5 pounds of monazite per cubic yard. Thicketty Creek drains the southwest half of Chero- kee County, but only the upstream half of the creek is underlain by monazite-bearing rocks (P. K. Theo— bald, Jr., written commun., 1954). In that part of Thicketty Creek the tenor of samples of riflie gravel was found to range from 0.1 to 8.6 pounds of monazite per cubic yard. High—tenor gravel was formerly mined for monazite at many places on small tributaries to Thicketty Creek (p. 234—235), particularly between Gafl'ney in Cherokee County and the settlement of Cow- pens in Spartanburg County (Keith and Sterrett, 1931, map). Resources of monazite in the upstream half of Thicketty Creek were estimated by Theobald to be 27,000 short tons in alluvium having an average tenor from grass roots to bedrock of 0.9 pound of monazite per cubic yard. A very large flood plain occupies the valley of Thicketty Creek upstream and down from the con- fluence with Little Thicketty Creek. The junction of the streams is a few miles downstream from the east edge of the monazite belt. Above the junction, Thicketty Creek drains an area of 40 square miles underlain by monazite-bearing schist, gneiss, and granite, and Little Thicketty Creek drains. an area of 20 square miles underlain by similar rocks. At the junction, and downstream from it, monazite-free schists occur; some are kyanitic or staurolitic, and others are chlorite bearing. A line of eight churn— drill holes was sunk by the US. Bureau of Mines across the large flood plain at the confluence of the two streams to appraise it as a source for detrital monazite (Hansen and Theobald, 1955, p. 11—19). The area drilled covers a little more than 3 million square yards, and the thickness of alluvium ranged from 14 to 22.5 feet. Most of the alluvium is very fine grained and con— sists of a mixture of clay and silt deposited during successive periods of overbank flooding. Each layer of clay and silt and underlying fine sand represents part of the suspended load of the flood—stage stream. These suspended—load deposits proved to be lean in heavy minerals. They overlie relatively thin layers of coarse sand and gravel deposited from the bedload. The bedload deposits contain most of the monazite (table 78). The dominance of fine—grained sediments in this flood plain reflects the mode of accumulation from overbank floods and the thoroughly weathered condi- THE GEOLOGIC OCCURRENCE OF MONAZITE tion of the crystalline rocks in the drainage basins. This dominance of fine-grained sediments also results in a low average tenor of 14.5 pounds of black sand and 0.41 pound of monazite per cubic yard (Hansen and Theobald, 1955, p. 25). Reserves in this flood plain were estimated to be 4,300 short tons of monazite. TABLE 78.—f-Am0unt of monazite related to class of sediment in the flood plum at the junction of Thicketty Creek and Little Thicketty Creek in Cherokee County, 3.0. [Modified from Hansen and Theobald (1955, p. 15, table 2)] Thickness 1 Tenor (lb per cu yd) Size grade of sediment Percent of Feet total Black sand Monazite thickness Silt, red to brown __________________ 3—5 19—36 0. 27—20. 85 0. 01—0. 40 Clay, gray, and fine sand- 0—11. 5 0—55 . 0 —19. 80 . 00- . 44 Fine sand __________________________ 0—5 0—36 . 0 -30. 34 . 00— . 76 Coarse sand and gravel ............ 4—13 21—81 10. 43—67. 01 . 5442. 24 1 Based on 8 holes drilled through flood-plain sediments 14—22,5 ft thick. A concentrate prepared from a composite sample from one drill hole on Thicketty Creek was reported to have the following composition (Hansen and Theobald, 1955, table 3, p. 18): Percent Percent Ilmenite _____________ 42 Kyanite and silliman— Epidote ______________ 3 ite _________________ 11 Zircon _______________ . 3 Magnetite ____________ 1 Garnet _______________ 11 Staurolite ____________ . 1 Quartz _______________ 16 Xenotime _____________ . 7 Amphibole ___________ 3 Spodumenc ___________ . 5 Monazite _____________ 5. 2 Columbite ____________ . 1 Rutile _______________ 4. 2 Uraninite ____________ Trace The presence of spodumene and columbite in the con- centrate suggests that small displays of the type of tin- spodumene pegmatite exploited for spodumene near Kings Mountain in Cleveland County, N.C., and as yet unrecognized in the drainage basin of Thicketty Creek, may be present in this part of Cherokee County. Mon- azite from the flood plain at the confluence of Thicketty Creek and Little Thicketty Creek contains 5.93 percent of Th02 and 0.50 percent of U308 (Hansen and Theo— bald, 1955, p. 24). SPARTA NBURG COUNTY The northwestern part of the high-tenor core of the monazite belt enters the north edge of Spartanburg County about 10 miles west of the Cherokee County line. The southeastern part enters from Cherokee County about 4 miles south of a line between the towns of Gafl'ney and Spartanburg. Thus, in the north- eastern part of Spartanburg County the core of the belt is about 20 miles wide. As it passes southwest- ward across Spartanburg County it narrows to a width of 6 miles at the junction of the North Tyger River SOUTH CAROLINA and Middle Tyger River. Within a matter of a few miles, however, the northwest side of the core of the belt expands abruptly toward the northwest along the divide between the Middle Tyger River and South Tyger River and enters Greenville County along the valley of the South Tyger River. The southeast side of the core of the belt persists in a fairly straight southwest-trending line and leaves Spartanburg County at the Enoree River about 2 miles downstream from the Laurens County line (Overstreet, 1962, fig. 2). The width of the core of the belt where it leaves the county is about the same as where it enters; how- ever, concentrates from alluvium in the core of the belt in the southwestern part of the county generally contain from 10 to 20 percent of monazite, whereas concentrates from alluvium in the core of the belt in the central and northeastern parts of the county con- tain from 10 to 30 percent of monazite. Concentrates from northwestern Spartanburg County generally have only 1—5 percent of monazite. Most streams in the southeastern part of the county, except in the vicinity of the junction of the North Tyger River and South Tyger River, are barren of monazite. Rutile in low percentages is associated with mona- zite in concentrates from alluvium in the northeastern part of the county. Its presence in this area is an extension of the prominent rutile—bearing area in central Cherokee County. Rutile is generally absent from concentrates in the middle part of Spartanburg County where the monazite-rich core of the belt nar- rows. Rutile again enters concentrates in two zones in the western and southwestern parts of the county: one zone about 5 miles wide, where concentrates from alluvium contain rutile, extends westward into Green- ville County along the South Tyger River; the other zone is about 12 miles wide and extends southwestward out of Spartanburg County along the line between Greenville County and Laurens County. Both are in the monazite-rich core of the belt, and the more northerly zone is associated with abundant sillimanite. Sillimanite is common in amounts between 1 and 5 percent of the concentrate in the monazite-rich north- eastern part of the county. Where the core of the monazite belt narrows near the junction of the North Tyger River and Middle Tyger River, Sillimanite is absent from concentrates, but along the divide between the Middle Tyger River and the South Tyger River a broad zone forms, in which concentrates again contain sillimanite. This zone extends westward into Green- ville County and corresponds to the westward exten- sion of the wide part of the core of the monazite belt. The southeast edge of this zone of Sillimanite-bearing concentrates, however, does not reach the southeast 239 limit of monazite-rich concentrates, which is 4 miles farther to the east (Overstreet, 1962, fig. 2). Almandine and ilmenite are common associates of monazite, sillimanite, and rutile in the core of the monazite belt in Spartanburg County. Almandine is most abundant in the northeastern and southwestern parts of the county where the highest percentages of monazite are present in concentrates from alluvium. From 5 to 20 percent of almandine is commonly present in concentrates from the core of the belt, but monazite-free concentrates to the northwest and south- east of the belt lack almandine. Throughout the core of the belt in Spartanburg County concentrates have from 40 to 60 percent of ilmenite. Epidote and magnetite are virtually absent from the core of the monazite belt in Spartanburg County, but both appear along the flanks of the belt and are the dominant minerals in concentrates from the north- west side of the core of the belt upstream from the confluence of the North Tyger River and Middle Tyger River. Monazite placers in Spartanburg County were ap- praised in 1952 by N. P. Cuppels (written commun., 1954), and summaries of the results have been pub- lished (Overstreet, Cuppels, and White, 1956; Over— street, Theobald, and Whitlow, 1959, p. 710). The summaries show that monazite-bearing tributaries to the Pacolet River in Spartanburg County contain at least 79,000 short tons of monazite, and monazite- bearing tributaries to the Tyger River in the county contain at least 44,000 short tons of monazite. The average tenor of alluvial sediments in the basin of the Pacolet River is 0.8 pound of monazite per cubic yard, but the average tenor of sediments along streams in the Tyger River basin is only 0.4 pound per cubic yard. This reflects the narrow width of the monazite- rich core of the belt in the Tyger River basin. Two monazite placers formerly mined in Spartanburg County are in the drainage basin of the Pacolet River and one, the Paine placer, is in the basin of the Enoree River (p. 235). Short south-flowing tributaries to the Enoree River in Spartanburg County were ap- praised by Cuppels together with the much longer east-flowing tributaries in Greenville County and Laurens County. The short streams entering the Enoree in Spartanburg County are discussed under Greenville County and Laurens County. The North Pacolet River and South Pacolet River and their tributaries upstream from their confluence drain a little more than 200 square miles in the northern part of Spartanburg County toward the west side of the monazite belt (N. P. Cuppels, written commun., 1954). Most concentrates contain between 1 and 5 240 percent of monazite, but the average tenor of the allu- vium is only 0.4 pound of monazite per cubic yard, and the resources were estimated to be 14,000 short tons of monazite. The average tenor and resources in the principal creeks in the area were inferred: Average tenor (lb of monazite Resources per cu yd) (short tons) Part of North Pacolet River ____________ 0.1 700 Obed Creek ___________________________ .9 1, 500 Bird Creek ____________________________ .4 400 Wood Branch _________________________ .5 700 Part of South Pacolet River ______________ .4 9, 500 Other streams _________________________ (1) 1, 200 1 Not reported. Downstream from the junction of the North Pacolet River and the South Pacolet River, the stream is known as the Pacolet River. It crosses the core of the mona- zite belt and emerges on the east side. Within the belt the principal tributary of Pacolet River is Buck Creek. Immediately southeast of the belt the Pacolet River is joined from the south by a long stream, Lawson Fork Creek, which also drains the core of the monazite belt. Alluvium on Buck Creek and nearby tributaries to the Pacolet River, including flood plains along the Pacolet, was estimated by N. P. Cuppels (written commun, 1954; Overstreet, Theobald, and Whitlow, 1959, p. 710) to contain 48,000 short tons of monazite and to have an average tenor of 1.4 pounds of monazite per cubic yard. Estimated average tenors and re- sources in monazite along the main creeks in the area were reported: Average tenor (lb of monazite Resources per cu yd) (short tons) Buck Creek ........................... 1. 9 16, 500 Casey Creek __________________________ 1. 8 2, 400 Cherokee Creek _______________________ 2. 1 3, 300 Island Creek __________________________ 1. 7 4, 300 Pole Ridge Creek ______________________ 5. 1 3, 200 Peters Creek __________________________ 2. 4 6, 000 Part of Pacolet River __________________ . 6 11, 000 Other streams _________________________ (1) 1, 300 1 N 01: reported. The Ezell placer mentioned listed on page 235 is on a tributary to Buck Creek. Four holes were drilled by the US. Bureau of Mines during January 1953 on the flood plain of the Pacolet River at a point about 6 miles northeast of Spartanburg (Hansen and Cuppels, 1955, p. 21—22). The alluvium averaged 22 feet in depth and consisted chiefly of sand. Samples from the four holes were found to contain an average of 19 pounds of black sand per cubic yard, of which 7—8 pounds was ilmenite, 0.57 pound was mona— zite, 0.5 pound was rutile, and 0.57 pound was zircon. THE GEOLOGIC OCCURRENCE OF MONAZITE Alluvium along Lawson Fork Creek and its main tributaries was estimated by N. P. Cuppels to contain at least 17,000 short tons of monazite and to have an average tenor of 0.7 pound per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). Estimated average tenors and resources in monazite in flood plains on Lawson Fork Creek and other streams in its drainage basin were reported to be as follows (N. P. Cuppels, written commun., 1954) : Average tenor (lb of monazite Resources per cu 1/d) (short tons) Meadow Creek ________________________ 0. 3 600 Green Creek __________________________ . 7 1, 000 Shoally Creek _________________________ 1. 0 1, 500 Lawson Fork Creek ____________________ . 8 13, 900 An area of about 400 square miles in the monazite belt is drained by the North Tyger River and South Tyger River in Spartanburg County. The southeast edge of the core of the belt is about 8 miles upstream from the junction of the rivers, but sparse monazite is found in tributaries as far southeast as the con- fluence (Overstreet, 1962, fig. 2). The best placers are in streams at the core of the belt, but the core is narrow and few large or rich placers are present. Monazite-bearing alluvium occurs along Beaverdam Creek and other tributaries to Fairforest Creek, in minor tributaries to parts of North Tyger River, Middle Tyger River, and South Tyger River, at the junction of North Tyger River and Middle Tyger River, and along Ferguson Creek and other streams entering the South Tyger River. Beaverdam Creek and other tributaries to Fairforest Creek were estimated by N. P. Cuppels to contain at least 7,900 short tons of monazite in alluvium having an average tenor of 0.5 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). Sediment having the greatest tenor in monazite in the drainage basin was found in streams draining the divide north of Beaverdam Creek near the Spar- tanburg Airport. Small areas of alluvium containing as much as 9.6 pounds of monazite per cubic yard were found in this area; however, the best placer observed was a part of the flood plain in the valley of Fairforest Creek between Arcadia and the mouth of Beaverdam Creek. In this long valley the flood- plain sediments have an average tenor of 0.7 pound of monazite per cubic yard and were estimated to contain 4,400 short tons of monazite. About 600 short tons of monazite in sediments having an average tenor of 1.2 pounds of monazite per cubic yard was reported by Cuppels for the headwater parts of the SOUTH CAROLINA main valley of F a1rforest Creek at and northwest of Arcadia. The combined resource in monazite of alluvium in the main valleys of Beaverdam Creek and Reedy Creek was estimated to be 1,500 short tons at an average tenor of 0.7 pound of monazite per cubic yard. Several small creeks between Roe- buck and Golightly at the southeast edge of the belt, and the main valley of Fairforest Creek between Beaverdam Creek and Bufl'alo Creek, were inferred to contain 1,400 short tons of monazite at an average tenor of 0.2 pound of monazite per cubic yard. Parts of the valleys of the North Tyger River, Middle Tyger River, and South Tyger River in western Spartanburg County and extreme eastern Greenville County near the northwest edge of the monazite belt were estimated by Cuppels to contain at least 9,200 short tons of monazite in alluvium having an average tenor of 0. 4 pound of monazite per cubic yard (Overstreet, Theobald, Whitlow, 1959, p. 710). As much as 11.9 pounds of monazite per cubic yard was found in one sample of gravel in the area, but 20 percent of the samples contained either no monazite or only a trace (N. P. Cuppels, written commun., 1954). The valley of North Tyger River upstream from Jordan Creek and the valley of Jordan Creek were estimated to have in combination 4,200 short tons of monazite in alluvium having an average tenor of 0.5 pound of monazite per cubic yard. In the valley of the Middle Tyger River upstream from the settlement of Duncan to the Beaverdam Creek area, including the lower valleys of Beaverdam Creek, Wolf Swamp Creek, and Spencer Creek, the tenor of the sediment was estimated to be only 0.1 pound of monazite per cubic yard, and the resources were inferred to be 1,700 short tons of monazite. The main valley of the South Tyger River from the vicinity of Duncan upstream to the county line has practically no flood plains. Small flood plains are present on Maple Creek south and southeast of Greer. The com- bined resources in monazite of the little flood plains on the South Tyger River above Duncan and on Maple Creek near Greer was estimated by Cuppels to be 3,300 short tons of monazite in sediment having an average tenor of 1.8 pounds of monazite per cubic yard. This high tenor results from the high average tenor of alluvium in Maple Creek, estimated to be 2.2 pounds of monazite per cubic yard. Maple Creek and the Greer area are in the core of the monazite belt, and concentrates commonly contain 20—30 percent of monazite. 241 The valleys of the North Tyger River and Middle Tyger River and their tributaries upstream from the junction of the rivers to the vicinity of Jackson Mills and Duncan were estimated by N. P. Cuppels (written commun., 1954) to contain at least 12,400 short tons of monazite. The distribution of monazite was found to be very variable, and tenors of alluvium in different streams ranged from 0.1 to 2.7 pounds of monazite per cubic yard with one stream, Grays Creek, being virtually barren of monazite. The drainage basins are in the narrowest part of the monazite belt in Spartanburg County. Downstream from the junction of the North Tyger River and South Tyger River, the main valley, also known as the North Tyger River, has broad and nearly continuous flood plains to the mouth of the South Tyger River. Large-volume low- tenor placers in this part of the river were estimated to contain about 5,400 short tons of monazite, and the combined resources were reported to be 17,800 short tons, the average tenor being 0.4 pound of mona- zite per cubic yard of sediment. Results of churn drilling in the large flood plain that extends down- stream for 3.5 miles from the junction of the North Tyger River and Middle Tyger River, described below, Show that the reconnaissance estimate of the amount of monazite is too low for the part of the river between this junction and the mouth of the South Tyger River. The large flood plain at the junction of the North Tyger River and Middle Tyger River was explored by the US. Bureau of Mines in January 1953 with 16 chum-drill holes (Hansen and Cuppels, 1953, p. 4—5). The deposit is at the southeast edge of the monazite belt and has received its sediment from weathered rocks in and northwest of the belt. The flood plain to a distance of 3.5 miles downstream from the confluence was estimated to contain 33.7 million cubic yards of alluvium, mostly sand, silt, and clay. From 5.44 to 15.39 pounds of heavy minerals were estimated per cubic yard of sediment, the average being 9.35 pounds per cubic yard. Only 4.2 percent of the heavy minerals was estimated to be monazite. The average tenor was estimated to be 0.39 pound of monazite per cubic yard with a range from 0.16 to 1.08 pounds per cubic yard. Resources in monazite for this part of the flood plain were inferred to be 6,570 short tons. Estimations of other minerals in- cluded 51,200 short tons of ilmenite, 2,100 short tons of rutile, 13,400 short tons of zircon, 5,500 short tons of kyanite and sillimanite, 390 short tons of xenotime, and 23,600 short tons of garnet. (See table 79.) 242 TABLE 79.—Mz'neralogical composition, in percent of concentrates from composited samples of alluvium from two drill holes in the flood plain downstream from the confluence of the North Tyger River and Middle Tyger River in Spartanburg County, 3.0. [Modified from Hansen and Cuppels (1955, table 2)] A B Arithmetic average Ilmenite ______________________ 36 29 32. 5 Quartz _______________________ 1 1 1 2 1 1. 5 Garnet _______________________ 13 17 15 Epidote ______________________ 10 10 10 Amphibole and biotite- 7 7 7 Zircon ______________ 10 7 8. 5 Monazite ____________ 6. 5 7. 9 7. 2 Kyanite and sillimanite ________ 3 4 3. 5 Magnetite ____________________ 1 . 5 . 75 Rutile _______________________ 1. 4 1. 3 1. 35 Sphene _______________________________ 1 . 5 Xenotime ____________________________ . 5 . 25 Black opaque minerals _________ 1. 5 .2 .85 Total __________________ 100. 4 97 4 98. 90 Two samples of monazite from the deposit at the junction of the North Tyger River and Middle Tyger River were analyzed by the U.S. Bureau of Mines and were found to have the following percentages (Hansen and Cuppels, 1955, p. 18): Percent Sample Th0; mo; A ______________________________________ 5. 87 0. 79 B ______________________________________ 5. 66 . 62 Average __________________________ 5. 76 . 70 At the southeast boundary of the monazite belt, Ferguson Creek and other streams entering the South Tyger River in Spartanburg County were found by N. P. Cupples to contain at least 9,400 short tons of monazite in flood—plain sediments having an estimated average tenor of 0.4 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). Concentrates from streams in the core of the monazite belt near Reidville have as much as 40 percent of monazite, but concentrates from tributaries to the South Tyger River southeast of the core of the belt in the area downstream from Chickenfoot Creek contain only 1—5 percent of monazite (N. P. Cuppels, written commun., 1954). No large or rich deposits are present. PARTS OF GREENVIILE COUNTY AND LAURENS COUNTY Streams in the northern one-third of Greenville County are monazite free or, in the extreme north- eastern part of the county, are the source of concen- trates that have 1—5 percent of monazite. The area is at the northwest flank of the monazite belt. Mona- zite is present in most streams south of a nearly east- trending line between the head of the Enoree River and the point on the South Tyger River where it leaves Greenville County. Most of Greenville County THE GEOLOGIC OCCURRENCE OF MONAZITE south of that line is in the core of the monazite belt, and concentrates generally contain from 10 to 20 per- cent of monazite. In the southern part of the county between the Saluda River and Reedy River, concen- trates commonly have 10—30 percent of monazite and locally as much as 60 percent. Along the southeast edge of Greenville County a broad monazite-bearing zone extends eastward 6—11 miles into Laurens County. Concentrates from alluvium in this area, which is part of the southeast flank of the monazite belt, contain from 1 to 10 percent of monazite. Rutile is present in concentrates from several parts of the county, but in two areas all concentrates con- tain rutile. One is an area that extends eastward from a point just north of the city of Greenville. The area is about 4 miles across from north to south and reaches into Spartanburg County on the east. In the part between Greenville and Paris Mountain, concen- trates contain from 1 to 10 percent of rutile and locally have as much as 20 percent. The other area overlaps the line between Greenville County and Laurens County and extends southward from the Enoree River to the Saluda River. Here concentrates contain from 1 to 5 percent of rutile. Sillimanite makes up 1 percent of the minerals in concentrates from streams in most of central Green- Ville County in the core of the monazite belt, but it is absent along the border between Greenville County and Laurens County (Overstreet, 1962, fig. 1). It is most abundant in the rutile-rich area around Paris Mountain. The distribution of almandine in con- centrates from alluvium conforms closely to that of sillimanite, rutile, and monazite. The central part of Greenville County is the richest in garnet, and at the core of the belt concentrates generally contain 5—20 percent of almandine. Along the border between Greenville County and Laurens County a zone where concentrates have 1—5 percent of almandine matches the southeast edge of the core of the monazite belt but does not extend as far eastward as the southeast edge of the flank of the belt. Very large amounts of ilmenite are present in con- centrates from streams in Greenville County south of the city of Greenville. In much of southern Green- Ville County concentrates contain from 70 to 90 per— cent of ilmenite. This ilmenite-rich zone persists into southwestern Laurens County, northwestern Abbeville County, and eastern, central, and western Anderson County. Epidote and magnetite are common in monazite- bearing concentrates from the northwest and south- east flanks of the belt in Greenville County and SOUTH CAROLINA Laurens County (Overstreet and Griflitts, 1955, fig. 1). 'In the northeastern part of Greenville County and across the county north of Paris Mountain, epidote generally makes up 1—20 percent of the concentrate, and magnetite constitutes 20—70 percent. Along the south border of the county and in western Laurens County, epidote rarely makes up more than 1 percent of the concentrate, but magnetite is uniformly present in percentages that increase eastward from 5 percent along the county border to 50 percent along the south- east edge of the monazite belt. During the period of. active monazite mining in the Carolinas in the late 1800’s and early 1900’s, the principal center for the industry in Greenville County was between Mauldin and Simpsonville (p. 235) on tributaries to the Enoree River and Reedy River. Several localities north and west of Mauldin were also mined, but records of output have not been published. The placers along monazite-bearing tributaries to the Enoree River in Greenville County and Laurens County were appraised by N. P. Cuppels in 1952, and placers along tributaries to the Reedy River were appraised by D. W. Caldwell in 1952 (Overstreet, Theobald, and Whitlow, 1959, p. 710). The main monazite-bearing streams entering the Enoree River are Mountain Creek, Gilder Creek, and Durbin Creek. Those tributary to the Reedy River are Laurel Creek, Huff Creek, Horse Creek, Rabon Creek, and Walnut Creek. Mountain Creek and other streams in the upper reaches of the Enoree River northeast of the town of Greenville were estimated by Cuppels to contain at least 5,100 short tons of monazite in alluvium having an average tenor of 0.4 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). The area is on the northwest edge of the mona- zite belt. Gravel from riflles in the streams generally contains less than 5 pounds of monazite per cubic yard, and most of the alluvium has only about one- tenth of that tenor. None of the formerly worked monazite placers in Greenville County (p. 235) is in this area. Gilder Creek and other tributaries to the Enoree River between the eastern outskirts of Greenville and a point on the Enoree River about a mile downstream from the northwest corner of Laurens County, in- cluding several small streams entering the Enoree from Spartanburg County, were estimated by N. P. Cuppels to contain at least 29,200 short tons of mona- zite in alluvium having an average tenor of 1.2 pounds of monazite per cubic yard (Overstreet, Whitlow, Theobald, 1959, p. 710). Several headwater branches of Gilder Creek were formerly mined for monazite 243 (p. 235). The Wyatt Smith placer, the W. M. Burdin mine, and the F. A. Alston mine were cited by Sloan (1908, p. 135—136). Of these the F. A. Alston mine was said to be the best, but no record of its output was given, although monazite was shipped. Five Mile Creek at a locality about 6 miles east of Greenville was also cited by Sloan as a placer (p. 235). Seem— ingly this is one of the tributaries to Brushy Creek north of Gilder Creek, but it has not been otherwise identified. In the Gilder Creek area the flood plains on the Enoree River are discontinuous and range in width from 150 to 600 feet except near the mouth of Gilder Creek where one widens to 1,600 feet. On the trib- utaries, flood plains are generally continuous and range in width from 200 to 400 feet. One flood plain on Gilder Creek is locally 1,000 feet wide. At most places the flood plain sediments in the valley of the Enoree River are 10—13 feet thick and on the trib- utaries are 6~11 feet thick (N. P. Cuppels, written commun., 1954). Inasmuch as the area is in the core of the monazite belt, all the flood-plain sediments contain monazite, and locally samples of riffle gravel from the head of Gilder Creek and Rocky Creek were reported by Cuppels to contain as much as 12—14 pounds of monazite per cubic yard. At several places on these creeks and Brushy Creek, gravel was esti- mated to have more than 20 pounds of ilmenite per cubic yard. The largest placer recognized by Cuppels is along Peters Creek, Abner Creek, and the Enoree River between the mouths of these two streams. In this deposit alluvium having an average tenor of 1.2 pounds of monazite was estimated to contain 8,900 short tons of monazite (N. P. Cuppels, written commun., 1954). Estimates prepared by Cuppels of the average tenor and resources in monazite in the Gilder Creek area follow: Tenor (lb of monazite per Resources cu yd) (short tons) Brushy Creek _________________________ 0. 7 1, 800 Rocky Creek __________________________ 2. 0 4, 200 Dillard Creek _________________________ 1. 9 1, 600 Abner Creek __________________________ 1. 8 3, 300 Peters Creek __________________________ 2. 1 3, 100 Gilder Creek __________________________ 1. 5 10, 100 Enoree River and other streams _________ (1) 5, 100 1 Not reported. No part of the monazite belt southwest of Gilder Creek with the exception of Huff Creek is equal to the drainage basin of Gilder Creek as a potential source for monazite. Several streams in North Carolina southwest of the Catawba River are as good or better. These include Knob Creek, Hinton Creek, Floyds Creek, and the downstream part of Henry Fork. 244 Durbin Creek and other tributaries to the Enoree River in Greenville, Laurens, and Spartanburg Coun- ties were estimated by N. P. Cuppels to have at least 7,200 short tons of monazite in alluvium having an average tenor of only 0.3 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). The area is on the east flank of the monazite belt. None of the streams is suitable for mining monazite. Laurel Creek and adjoining streams in the upper reaches of the Reedy River in Greenville County were reported by D. W. Caldwell to contain at least 12,600 short tons of monazite in flood-plain sediments having an average tenor of 0.8 pound per cubic yard (Over— street, Theobald, and Whitlow, 1959, p. 710). The Reedy River rises on the southwest side of Paris Mountain. South-flowing tributaries to the river south of Paris Mountain have beheaded east-flowing streams that enter the Enoree River; thus, Laurel Creek has beheaded Gilder Creek and Richland Creek has cap- tured the headwaters of Brushy Creek northeast of Greenville (D. W. Caldwell, written commun., 1954). Upstream from Greenville the flood plains on the Reedy River and its tributaries are broad, regular, and continuous, but downstream between Greenville and Conestee Lake they are irregular in width and discon- tinuous. Where they are broad and continuous the valleys are carved in massive granite and schist, and where they are irregular the valley walls are gneiss. Alluvium along the Reedy River between Paris Moun- tain and Conestee Lake averages 11.4 feet in thickness. On tributaries entering the river from the north the alluvium is a little deeper than on streams that enter from the south, but both sets of flood plains are shallower than those on the river. Most of the area is northwest of the core of the monazite belt, but south of Greenville the streams are in the core of the belt. Concentrates from alluvium in the core contain 20—40 percent of monazite, but con- centrates from streams on the northwest flank of the belt have only 1—5 percent of monazite. Monazite is associated with ilmenite and garnet in all the concen- trates. Sillimanite, zircon, and magnetite are common in small amounts, and concentrates with sparse mona- zite have abundant epidote. Rutile is sparse. The distribution of heavy minerals in the stream sediments was shown by D. W. Caldwell (written commun., 1954) to be related to the kinds of rocks drained by the streams (table 80). Concentrates from drainage basins that expose epidote- and magnetite-bearing monazite—free massive granite in monazite-bearing schists contain appreciably less monazite and more epidote and magnetite than concentrates from basins THE GEOLOGIC OCCURRENCE OF MONAZITE that do not expose the massive granite. Structural relations have been interpreted to show that the mona- zite—free granite is posttectonic with respect to the episode of deformation in which monazite was formed in the schist and gneiss (Overstreet and Bell, 1962, map). TABLE 80.—Distribution of detrital heavy minerals in concentrates from rifile sand and gravel in relation to source rocks in the drainage basins of Laurel Creek and other tributaries to the Reedy River in Greenville County, 8.0. [Modified from D. W. Caldwell (written commun., 1964). Symbol used: _-, not calculated] Average of 7 samples Average of 5 samples from area underlain from area underlain chiefly by granite chiefly by massive gneiss granite and schists Abundance Tenor (1b Abundance Tenor (lb (percent) per cu yd) (percent) per cu yd) Monazite ________________ 18 6. l 3 0. 5 Ilmenlte _________________ 60 22. 8 56 3. 8 Garnet... _ l7 5. 4 2 . 2 Zircon _________ 1 3 4 . 3 Rutile _________ Trace- -__ .............. 1 . l Sillimanite- _ _ _ _ 3 10 . 6 Magnetite ________ __ .............. 10 .............. Epidote __________________ Trace .............. 14 .............. The broad valleys and large flood plains upstream from Greenville are in the area where the monazite-free granite is present; hence, these fine deposits of fluvial sediments contain only about 0.2 pound of monazite per cubic yard. Downstream from Greenville Where irregular and interrupted flood plains are found, the monazite-free granite is absent, and the alluvium in different streams was reported to contain from 1.2 to 1.8 pounds of monazite per cubic yard (D. W. Caldwell, written commun., 1954): Tenor (lb of monazite per Restmrces ca yd) (short tans) Headwaters of Reedy River _____________ 0. 2 1, 400 Long Branch __________________________ . 2 (1) Reedy River downstream from Greenville to Conestee Lake ____________________ 1. 5 2, 800 Richland Creek ________________________ 1. 8 2, 400 Brushy Creek _________________________ 1. 4 2, 600 Laurel Creek __________________________ 1. 3 2, 900 Other streams _________________________ (2) 500 Total ___________________________________ 12, 600 1 Less than 100 tons. I Not reported. The Alexander brothers’ placer mentioned by Sloan (1908, p. 133) was probably on a branch of Brushy Creek, and the J. S. Hill, Jr., placer was on a down- stream tributary to Laurel Creek east of Conestee Lake (Sloan, 1908, p. 134). Hull Creek and neighboring tributaries to the Reedy River between Conestee Lake and Fork Shoals in Greenville County were estimated by D. W. Cald- well to contain 17,900 short tons of monazite in alluvium having an average tenor of 2.1 pounds of monazite per cubic yard (Overstreet, Theobald, and SOUTH CAROLINA Whitlow, 1959, p. 710). Except for the Gilder Creek area this is probably the site of the richest monazite deposits in the South Carolina Piedmont south of Cherokee County. Sloan (1908, p. 134-135) listed five placer deposits on northern tributaries to the Reedy River immediately downstream from Conestee Lake. These were the Thomas Fowler placer, the A. White placer, the Molly Garrett placer, the Brooks mine, and the J. R. Bramlet placer (p. 235). A large output was attributed to the Brooks mine, but records have not been published. The Huff Creek area is underlain by granite gneiss, biotite schist, sillimanite schist, and biotite gneiss in the core of the monazite belt (D. W. Caldwell, written commun., 1954; Overstreet, 1962, fig. 2). The widest flood plains are in valleys carved in the schists. Valleys in gneiss are narrow, and the flood plains are small and discontinuous. Mostly the flood plains are 200—7 50 feet wide in the areas of schist and 200- 300 feet wide in the areas underlain by gneiss. At its widest the flood plain on Huff Creek reaches 1,300 feet in width and that on the Reedy River attains 1,700 feet, but flood plains on the smaller streams do not exceed 600 feet. Sediments on the tributaries to the Reedy River are about 6—12 feet thick, and alluvium in the valley of the river is about 14—22 feet thick. Concentrates from stream sediments contain as much as 60 percent of monazite at the center of the area just west of the junction of Rock Creek with the Reedy River (D. W. Caldwell, written commun., 1954). Outward from the center the amount of monazite decreases to a lower limit of about 30 percent of the concentrate. Typical suites of heavy minerals consist of ilmenite, monazite, and garnet with small amounts of magnetite, zircon, and sillimanite. Locally a trace of rutile, staurolite, tourmaline, amphibole, epidote, sphene, and xenotime is present. In more than one- third of the samples of riflie gravel and one-fifth of the samples of riffle sand, the tenor in monazite was es— timated to exceed 5 pounds per cubic yard. The average tenor of alluvium from grass roots to bedrock is also high (D. W. Caldwell, written commun., 1954): Tenor (lb of monazite per Resources cu yd) (short tons) Rock Creek ___________________________ 1. 2 1, 800 Upper part of Hufl" Creek _______________ 4. 3 2, 500 North central Huff Creek and tributary_- 4. 5 3, 800 South central Huff Creek _______________ 2. 8 3, 300 Lower part of Hufl Creek _______________ 1. 4 900 Baker Creek __________________________ 2. 2 1, 400 Head of Little Creek ___________________ 3. 6 1, 700 Other streams _________________________ (1) 2, 500 Total ___________________________________ 17 , 900 Not reported. 245 Streams having the highest tenors in monazite, ilmenite, garnet, zircon, and sillimanite are in areas chiefly underlain by granite gneiss. Streams on biotite schist and biotite gneiss are the poorest sources for monazite. The upper part of Huff Creek and the head of Little Creek seem to contain the highest—grade deposits in the area, but neither of these localities seems to have been mined. Horse Creek rises in Greenville County and enters the Reedy River in Laurens County. The creek and nearby tributaries to the Reedy River are southeast of the core of the monazite belt, and the southwestern and southeastern parts of the area are even outside the southeast flank of the belt. Most concentrates are lean in monazite and some are barren. The tributaries to the Reedy River were estimated to contain about 3,000 short tons of monazite in alluvium having an average tenor of 0.3 pound per cubic yard (Overstreet, Theo- bald, and Whitlow, 1959, p. 710). Alluvium along the large flood plain in the valley of the Reedy River between Fork Shoals in Greenville County and the mouth of Horse Creek in Laurens County was thought possibly to contain as much as 0.5 pound of monazite per cubic yard because the river rises a few miles north of the monazite belt and traverses it (D. W. Caldwell, written commun., 1954); the alluvium probably has only about half that tenor. The headwaters of North Rabon Creek and South Rabon Creek originate near Fountain Inn in Green— ville County and flow southward to join about 7 miles west of the city of Laurens in Laurens County. From this junction the stream is known as Rabon Creek. Rabon Creek empties into Lake Greenwood. North Rabon Creek and South Rabon Creek rise on the east side of the core of the monazite belt, and the mouth of Rabon Creek is on the southeast flank of the belt. Resources in monazite of the two streams to their confluence was estimated by D. W. Caldwell to be about 12,600 short tons in alluvium having an average tenor of 0.4 pound of monazite per cubic yard (Over- street, Theobald, and Whitlow, 1959, p. 710). The resources in North Rabon Creek were estimated to be 5,000 short tons in sediments averaging 0.3 pound of monazite per cubic yard, and in South Rabon Creek they were said to be 7,600 short tons in alluvium having an average of 0.5 pound of monazite per cubic yard (D. W. Caldwell, written commun., 1954). An estimate of 10,900 short tons of monazite was made for the same area from the results of drilling 19 holes in January and February 1953 (Hansen and Caldwell, 1955, p. 6). The average tenor of the flood—plain sedi- ments as found by churn drilling is 0.42 pound of monazite per cubic yard. 246 Sediments in the flood plains of North Rabon Creek and South Rabon Creek contain an estimated 5.5 pounds of black sand per cubic yard. This sand con— sists mostly of ilmenite and amphibole. Mineralogical composition, in percent, of concentrates from sed- iment from drill holes in the flood plain of South Rabon Creek, Laurens County, 8.0. [Modified from Hansen and Caldwell (1955, table 3)] Upstream Downstream Ilmenite ________________________________ 43 31 Amphibole and biotite ____________________ 19 7 Quartz _________________________________ 14 13 Monazite _______________________________ 7. 4 9. 4 Xenotime _______________________________ . 5 . 3 Zircon __________________________________ 3. 5 5. 6 Garnet _________________________________ 3 2 Epidote ________________________________ 2 24 Magnetite ______________________________ 3 . 1 Rutile __________________________________ 2 5 Kyanite and sillimanite ___________________ 1 1 Opaque minerals _________________________ 1 1 Total _____________________________ 99. 4 99. 4 Monazite from North Rabon Creek and South Rabon Creek was analyzed by the US. Bureau of Mines and found to contain the following percentages of thorium oxide (Hansen and Caldwell, 1955, p. 16): Percent? Th0: UIOT North Rabon Creek __________________________ 7. 85 0. 33 6. 95 . 30 6. 12 . 46 South Rabon Creek __________________________ 5. 51 . 49 6. 30 . 49 Average ______________________________ 6. 55 . 41 Most of the monazite in the Rabon Creek area comes from biotite granite gneiss (D. W. Caldwell, written commun., 1954). The amount of thorium oxide in this monazite is somewhat greater than the amount in monazite from placers on the Broad River, Tyger River, and Big Generostee Creek, where the monazite comes mainly from schists and gneiss. Monazite was reported by Sloan (1908, p. 129) to occur on Walnut Creek, which is the southernmost of the large western tributaries to the Reedy River. The creek and several small western and northern tribu- taries to the river in northwestern Laurens County about 5 miles upstream from Lake Greenwood are on the southeast flank of the monazite belt. Concen- trates from these streams consist of dominant ilmenite and magnetite having 1—20 percent of monazite and a trace of rutile and epidote (D. W. Caldwell, written commun., 1954). Sporadically distributed associated heavy minerals are, in order of frequency of appear— ance: amphibole, zircon, garnet, staurolite, sphene, THE GEOLOGIC OCCURRENCE OF MONAZITE sillimanite, kyanite, xenotime, tourmaline, and spinel. The streams were appraised by Caldwell in 1952 and were estimated to contain about 1,700 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 710). The average tenor of alluvium was estimated to be 0.5 pound of monazite per cubic yard. PARTS OF GREENVILLE, PICKENS, ANDERSON, ABBEVILLE, GREENWOOD, OCONEE, AND LAURENS COUNTIES The northwest edge of the core of the monazite belt enters in northwest Anderson County where its boundary with Pickens County reaches the Saluda River (Overstreet, 1962, fig. 2). From this point the northwest edge of the core of the belt passes south- ward into Abbeville County at the place Where the Rocky River crosses the boundary between Anderson County and Abbeville County. The core of the belt is in eastern Anderson County. Concentrates from the core in this area contain only 5—10 percent of monazite, and this area is the leanest part of the core in South Carolina. Locally, as at the Saluda River near Pickens County and near Abbeville County and at the Rocky River at the Abbeville County line, monazite makes up as much as 20 percent of the concentrate. To the northwest of the core, there is a broad area in southwestern Anderson County that constitutes the northwest flank of the belt where concentrates contain between 1 and 5 percent of monazite. The northwest edge of the flank of the belt extends west—southwest- ward 1—4 miles south of the north border of Anderson County and crosses the Tugaloo River about a mile upstream from the mouth of the Seneca River. A few small outlying areas where concentrates from alluvium contain less than 5 percent of monazite occur along the south borders of Pickens County and Oconee County. The most notable of these is about 5 miles north of the point where the boundary between Oconee County and Anderson County touches the Tugaloo River. The southeast edge of the core of the monazite belt passes west—southwestward from the intersection of the Saluda River with the Anderson-Abbeville County line. The core is only 4—8 miles wide. It occupies most of the area between the Rocky River and Little River in Abbeville County. The broad southeast flank of the monazite belt enters Abbeville County and Greenwood County from Laurens County. Its full width in Greenwood County has not been determined, but it extends southeastward at least to the upper reaches of Lake Greenwood. Rutile in abundances up to 20 percent of the con- centrate, but mainly less than 5 percent, is present more or less along the core of the monazite belt south- westward across northern Abbeville County from the SOUTH CAROLINA Saluda River to the Rocky River. It is also present in northern Greenwood County near the Saluda River and in southern Anderson County near the Rocky River. Elsewhere in Anderson County, concentrates have less than 1 percent of rutile except for a 40- square-mile area between the city of Anderson and the Seneca River and four scattered small areas from which one to three rutile-bearing concentrates were collected. Rutile is also present in the monazite-rich outlying area in Oconee County 5 miles north of the Tugaloo River. Sillimanite is absent in concentrates from most of Anderson County, and it is not present in concentrates from Pickens County or Greenwood County. Its prin- cipal occurrence in this part of the monazite belt is along the Saluda River from a point about a mile down- stream from the Pickens County line to a point about 8 miles upstream from the line between Anderson County and Abbeville County. Sillimanite is also present in concentrates from the core of the belt at the head of the Little River and adjacent parts of the Rocky River in Anderson County and Abbeville County. Silimanite is present in concentrates from the monazite—rich out— lying area in Oconee County 5 miles north of the Tugaloo River. Almandine is absent from or sparse in most concen— trates from alluvium in northern, western, and south— western Anderson County. It is most common in the core of the belt along the Saluda River northeast of the city of Anderson. It is also present in low con— centrations on the southeast flank of the belt in north- ern Greenwood County and Abbeville County and in the core of the belt from the headwaters of the Little River to the Rocky River at the border between Anderson County and Abbeville County. Almandine makes up 1»5 percent of the heavy minerals in con— centrates from the monazite-rich outlying area in Oconee County 5 miles north of the Tugaloo River. Ilmenite is the most abundant component of concen~ trates from alluvium in eastern, central, and western Anderson County, and it is also very abundant in con- centrates from the monazite-bearing area in Oconee County north of the Tugaloo River. In these areas ilmenite makes up 70—90 percent of the concentrate. Elsewhere in Anderson County and in adjacent parts of Pickens, Oconee, and Abbeville Counties, ilmenite composes 10—60 percent of the concentrate. Narrow zones having 70 percent or more of ilmenite in con- centrates from alluvium are present in northeastern Abbevile County and Greenwood County. Epidote is commonly present in amounts ranging from 1 to 5 percent of the concentrate along the north- west flank of the belt, in areas barren of monazite in northeastern and central Anderson County, and in 247 southern Pickens County and Oconee County. Epi- dote is also common in concentrates from the core and southeast flank of the belt in northern Abbeville County and Greenwood County. It is generally absent from the small monazite-rich outlying area in Oconee County north of the Tugaloo River. Magnetite is scarce in concentrates from the core of the monazite belt in Anderson County and Abbeville County, but it is common in concentrates from the flanks of the belt or inmonazite-free parts of Pickens, Oconee, Anderson, Abbeville, and Greenwood Counties (Overstreet and Grilfitts, 1955, pl. 1). Ten areas of monazite-bearing streams in these counties were appraised by D. W. Caldwell in 1952 (Overstreet, Cuppels, and White, 1955; Overstreet, Theobald, and Whitlow, 1959, p. 710). Four of these areas are drained by tributaries to the Saluda River in Greenville, Pickens, Anderson, Abbeville, and Greenwood Counties. Six are drained by tributaries to the Savannah River and are discussed in a follow— ing section under “Parts of Anderson, Abbeville, and Oconee Counties.” The four areas in parts of Green- ville, Pickens, Anderson, Abbeville, and Greenwood Counties are around Big Brushy Creek, Grove Creek, Broad Mouth Creek, and Turkey Creek. Big Brushy Creek rises northwest of the monazite belt in Pickens County, flows 12 miles southeastward through Pickens County and Anderson County, and empties into the Saluda River near the town of Pied- mont (D. W. Caldwell, written commun., 1954). Up- stream along the Saluda River from the mouth of Big Brushy Creek to Saluda Lake several small monazite- bearing tributaries enter the river from Anderson County and Pickens County and eight very short streams reach the river from Greenville County. All these streams are northwest of the core of the monazite belt which results in alluvium having the low average tenor of only 0.2 pound of monazite per cubic yard. Resources were estimated to be about 1,900 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 710). Grove Creek enters the Saluda River in Greenville County about 3.5 miles downstream from Pelzer which is on the other side of the river in Anderson County (D. W. Caldwell, written commun., 1954). The lower tributaries to Grove Creek were mined at several places in the early 1900’s (Sloan, 1908, p. 133); the Berry Waldrop placer and the Dave Terry placer were mentioned (p. 235). Monazite from the Waldrop deposit was said by Sloan to be an important factor in the South Carolina industry. On the opposite side of the Saluda River, placers were also known in Anderson County on lower tributaries to Hurricane 248 Creek 3.5 miles north-northwest of Pelzer and on tributaries to the middle part of Big Creek about 1 mile south of Pelzer (p. 235). The output, if any, at these deposits was not recorded (Sloan, 1908, p. 132). The headwaters of Grove Creek, Hurrican Creek, Big Creek, and other streams in this area originate in granite gneiss and interlayered biotite schist northwest of the core of the monazite belt. Their lower ends, or middle and lower reaches are in the core, and eastern tributaries to Grove Creek rise in the core of the belt. Sillimanitic rocks are especially common in and near the parts of Hurricane Creek and Big Creek where placers were formerly mined. Ilmenite is the most abundant mineral in concentrates from sediments in the Grove Creek area (D. W. Caldwell, written commun., 1954) : Average tenor of riflle sediments (lb per cu yd) Grove Creek Hurricane Big Creek Creek Ilmenite __________________ 17. 5 12. 7 9. 1 Monazite _________________ 1. 4 1. 3 2. 2 Zircon ___________________ . 5 . 9 . 2 Garnet ___________________ . 5 1. 8 . 8 Sillimanite ________________ . 1 . 3 . 4 Areas rich in magnetite and epidote at the head of Hurricane Creek are virtually devoid of monazite. Resources in monazite in flood—plain sediments along Grove Creek and adjacent tributaries to the Saluda River were estimated by Caldwell to be about 5,600 short tons in alluvium having an average tenor of 0.3 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). The tenors and resources of individual streams were reported (D. W. Caldwell, written commun., 1954) to be as follows: Tenor (lb of monazite per Resources cu yd) (short tons) Hurricane Creek _______________________ 0. 5 1,500 Grove Creek __________________________ . 2 1 ,900 Big Creek _____________________________ . 4 2,200 Total ___________________________________ 5, 600 Broad Mouth Creek and other tributaries to the Saluda River in Anderson, Greenville, Abbeville, and Laurens Counties were estimated by D. W. Caldwell to have at least 14,300 short tons of monazite in flood—plain deposits having an average tenor of 0.8 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). Broad Mouth Creek heads in east-central Anderson County and enters the Saluda River in Abbeville County. In the same general area, THE GEOLOGIC OCCURRENCE OF MONAZITE Little Creek and Tony Creek flow into the Saluda River from Abbeville County and Anderson County, respectively, and Mountain Creek reaches the river in Greenville County. Biotite gneiss and biotite schist are the principal rocks in the drainage basins of Broad Mouth Creek and Mountain Creek (D. W. Caldwell, written com- mun., 1954). Locally granite gneiss and weakly foliated granite crop out. Throughout the area, but especially around Honea Path in Anderson County, dikes and sills of pegmatite are common. Concen- trates from alluvium in the western and central parts of the area are much leaner in monazite than concen- trates from the southern and eastern parts. Around Honea Path and between that town and the point where the Anderson-Abbeville County line meets the Saluda River, concentrates contain as much as 30 percent of monazite. Concentrates consist mostly of ilmenite but have some monazite, magnetite, zircon and small amounts of garnet and rutile; epidote and amphibole are present locally. Rifiie sand was re- ported to contain as much as 13.8 pounds of ilmenite per cubic yard (D. W. Caldwell, written commun., 1954) : Average tenor of riflie sediments (lb per cu yd) Mountain Little Creek Broad Mouth Creek Creek Ilmenite __________________ 9. 5 8. 6 13. 8 Monazite _________________ 1. 0 1. 0 1. 8 Zircon ___________________ Trace . 1 . 5 Garnet ___________________ . 1 Trace . 1 Rutile ___________________ . 1 Absent Trace Several samples of riflie gravel from small streams around Honea Path in Anderson County were found by Caldwell to have a tenor of 5 pounds of monazite per cubic yard or more. Detrital monazite had been mined near the town in the early 1900’s (Sloan, 1908, p. 129). The tenor and resources in monazite of sediments along individual streams in the Broad Mouth Creek area were estimated by D. W. Caldwell (written commun., 1954) to be as follows: Tenor (lb of monazite per Resources cu 11d) (short tom) Mountain Creek _______________________ 0. 7 2, 800 Tony Creek ___________________________ . 4 400 Little Creek ___________________________ . 7 1, 000 Broad Mouth Creek ____________________ 1. 0 9, 000 Other streams _________________________ (1) 1, 100 Total _____________________________________ 14, 300 1 Not reported. SOUTH CAROLINA Sediments along the large flood plains on the Saluda River in this area probably contain about a quarter of a pound of monazite per cubic yard. The headwaters of Turkey Creek originate in eastern Anderson County at Honea Path, and the stream enters Lake Greenwood on the Saluda River in Green- wood County. The stream rises in the core of the monazite belt and flows out the southeast flank of the belt. Alluvium in the headwaters of Turkey Creek contains about 1.2 pounds of monazite per cubic yard, but sediments in the lower reaches of the stream have only about 0.2 pound of monazite per cubic yard (D. W. Caldwell, written commun., 1954). Resources in monazite were estimated by Caldwell to be about 4,500 short tons, and the average tenor of alluvium in Turkey Creek and nearby tributaries to the Saluda River was estimated to be 0.4 pound‘ of monazite per cubic yard from grass roots to bedrock (Overstreet, Theobald, and Whitlow, 1959, p. 710). PARTS OF ANDERSON, ABBEVILLE, AND OCONEE COUNTIES Placers in six areas drained by monazite-bearing tributaries to the Savannah River in parts of Ander- son, Abbeville, and Oconee Counties were appraised by D. W. Caldwell in 1952, and one of the areas was explored by the US. Bureau of Mines in 1953. The areas examined by Caldwell are around Big Beaverdam Creek in central Anderson County, Broadway Creek, Hogskin Creek, Big Generostee Creek, Saddler Creek, and Big Beaverdam Creek and Little Beaverdam Creek in western Anderson County and Oconee County. Big Beaverdam Creek in central Anderson County is the headwaters of the Rocky River. It is north and east of the city of Anderson in an area underlain by granite gneiss, granite, biotite schist, and biotite gneiss (D. W. Caldwell, written commun., 1954). It is on and northwest of the northwest flank of the monazite belt in an area lean in or devoid of monazite. Flood- plain sediments were estimated to have an average tenor of only 0.1 pound of monazite per cubic yard, and the resources were appraised as about 2,700 short tons of monazite (Overstreet, Theobald, and Whitlow, 1959, p. 710). The northeastern and southern parts of the area drained by Broadway Creek and other streams tribu- tary to the Rocky River in Anderson County are un- derlain by monazite—bearing crystalline rocks, but the rocks in the western, central, and eastern parts of the area are very lean in or lack monazite. Therefore, alluvium in the northeastern and southern parts of the area contains more detrital monazite than alluvium in the other parts of the area (D. W. Caldwell, written commun., 1954). 238—813—67———17 249 The average tenor and total resources in monazite were estimated to be 0.5 pound per cubic yard and about 15,000 short tons (Overstreet, Theobald, and Whitlow, 1959, p. 710) : Tenor _(lb of Northeastern: “”3575,” (fiifim?) West Rock Creek __________________ 1. 9 2, 300 Watermellon Creek ________________ . 4 600 East Rock Creek __________________ . 2 100 Broadway Creek to mouth of Cup- board Creek _____________________ . 5 1, 300 Cupboard Creek ___________________ . 7 1, 550 Central and eastern: Broadway Creek to Broadway Lake_- . 2 220 Pea Creek ________________________ .2 165 Neal Creek _______________________ Trace Trace Beaver Creek _____________________ . 3 1, 550 Cherokee Creek ___________________ . 0 None Upstream part of Hen Coop Creek--- Trace Trace Southern: Downstream part of Hen Coop Creek- 1. 1 5, 000 Bear Creek _______________________ . 8 2, 100 Western: Governors Creek __________________ . 3 185 Average, weighted _______________ . 5 15, 070 Concentrates from alluvium in the monazite-bearing parts of the area had less zircon, magnetite, and ilmen- ite, and more garnet and sillimanite than concentrates from alluvium in the monazite—free parts of the area (D. W. Caldwell, written commun, 1954). Hogskin Creek and a group of other streams in southeastern Anderson County and northeastern Abbe— Ville County are the headwaters of the Little River in the core of the monazite belt. Biotite schist, biotite gneiss, and granite gneiss are the main varieties of rocks underlying the drainage basins. Ilmenite is the principal mineral in the concentrate. It is accompanied by much smaller amounts of monazite, magnetite, garnet, zircon, rutile, and sillimanite. Changes take place between the northern and southern parts of the area in the composition of concentrates from gravel and coarse sand in the streams. The variations in the same class of sediment are related to changes in the dominant types of rocks in the drainage basins. In northern streams, such as Barker Creek and Blue Barker Creek, where biotite schist and biotite gneiss are common, ilmenite is more abundant than in south- ern streams, such as Hogskin Creek and Little Hogskin Creek, where granite gneiss or interlayered schists and granite gneiss are dominant. Another southward change in the composition of concentrates from gravel and coarse sand is an increase in monazite, zircon, and rutile. The amounts of garnet and sillimanite remain 250 about the same (D. W. Caldwell, written commun., 1954): Tenor (lb of monazite per cu yd) Northern streams Southern streams Ilmenite ________________________ 4 —50 0.9 —35. 7 Monazite _______________________ . 1 — 6 .4 — 8. 3 Zircon __________________________ 0 — 1. 2 .06— 2. 1 Rutile __________________________ 0 0 — 1.0 Garnet _________________________ . 07- . 6 0 —- 1. 0 Sillimanite ______________________ 0 — .6 0 — .3 These variations are only faintly reflected in the average tenor for monazite in all classes of sediment. As estimated by Caldwell the average tenor of Barker Creek and its tributaries is 1.1 pounds of monazite per cubic yard, and that of Hogskin Creek and its tribu- taries is 1.4 pounds per cubic yard. Resources in these two basins were estimated to be 5,000 short tons and 7,000 short tons, respectively. Other streams in the area bring the resources to about 15,300 short tons of monazite in sediments having an average tenor of 1.2 pounds of monazite per cubic yard (Overstreet, Theo— bald, and Whitlow, 1959, p. 710). Big Generostee Creek rises west of the city of Anderson and flows southwestward for 14 miles to the Savannah River in Anderson County. The largest tributary to Big Generostee Creek is Mountain Creek, which rises south of Anderson and enters Big Genero- stee about 6 miles upstream from the Savannah River. Biotite schist and biotite gneiss are the main varieties of rock in the basins of Mountain Creek and Big Generostee Creek upstream from its junction with Mountain Creek. From the junction to the Savannah River the basin of Big Generostee is underlain chiefly by granite gneiss. Flood plains are long, broad, and continuous from the headwaters to within about 2 miles of the Savannah River. For the most part the depth of the flood-plain sediments is about 7 .5—14 feet, but locally the depth can be as much as 24 feet. Valley floors beneath the alluvium are flat and consist of saprolite. The streams are on the northwest flank of the mona- zite belt where concentrates from alluvium contain a trace to 5 percent of monazite. The upper parts of Mountain Creek are very lean in monazite. Very large percentages of ilmenite are present throughout the area, which tends to reduce compositional differences among the sediments from different streams. Zircon occurs in about two-thirds of the concentrates and is locally very abundant in Mountain Creek. Rutile, garnet, and sillimanite are sparsely present, small amounts of epidote are common, and amphibole is sporadically distributed in small percentages (D. W. Caldwell, written commun., 1954). THE GEOLOGIC OCCURRENCE OF MONAZITE Resources in monazite were appraised by Caldwell in 1952 as about 11,000 short tons in sediment having an average tenor of 0.5 pound of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). The valleys of Big Generostee Creek and Moun- tain Creek were explored with 12 churn—drill holes by the US. Bureau of Mines in 1953 and were estimated to contain 9,500 short tons of monazite (Hansen and Caldwell, 1955, p. 22). Alluvium in these streams was estimated by the Bureau to contain 12 pounds of black sand per cubic yard including 0.44 pound of monazite. Monazite from Big Generostee Creek was analyzed by the US. Bureau of Mines and found to contain 4.21 percent of Th02 and 0.44 percent of U308 (Hansen and Caldwell, 1955, p. 24). Individual streams in the area, and segments of Big Generostee Creek display generally decreasing average tenors in monazite southward from the head of the basin (D. W. Caldwell, written commun, 1954) : Tenor (lb of monazite per Resources cu yd) (short tom) Whitner Creek and Crawford Creek ______ 1. 6 2,850 Three Mile Creek, Five Mile Creek, Rich- land Creek, and Big Generostee Creek to a point a mile downstream from Richland Creek _____________________ 1. 1 4, 100 Big Generostee Creek to the mouth of Mountain Creek _____________________ . 2 330 Big Generostee Creek to the Savannah River ______________________________ Trace _______ Mountain Creek _______________________ . 1 650 Devil Fork Creek ______________________ . 6 1,250 Weem Creek __________________________ . 2 460 Other streams _________________________ (1) 1, 730 Total ____________________________________ 11,370 1 Not reported. Saddler Creek and three short, steep tributaries to the Savannah River and Seneca River about 15 miles west of Anderson in Anderson County are on the northwest flank of the monazite belt in an area under- lain in the south by granite gneiss and in the north by biotite schist and biotite gneiss. Alluvium in the streams on the granite gneiss is about twice as rich in monazite as alluvium along the streams in the schist. Resources of these streams were estimated in 1952 by D. W. Caldwell to be about 3,900 short tons of mona- zite in sediment having an average tenor of 2.0 pounds of monazite per cubic yard (Overstreet, Theobald, and Whitlow, 1959, p. 710). Big Beaverdam Creek and Little Beaverdam Creek in western Anderson County and southwestern Oconee County partly drain an area of monazite-rich crys- talline rocks west of the monazite belt and partly drain monazite-free rocks. The creeks head in Oconee County and flow southeastward to the. Tugaloo River. SOUTH CAROLINA Along their lowermost parts the streams have cut gorges in unweathered biotite schist and biotite gneiss. Upstream from the gorges the streams have continuous flood plains of irregular width which ex- tend to the very heads of the creeks. On both streams the widest flood plains begin at the upper ends of the gorges and extend 1.5 miles upstream on Big Beaverdam Creek and 1.2 miles upstream along Little Beaverdam Creek. At their widest parts these two flood plains are 2,400 feet and 1,700 feet across, respectively. Concentrates from monazite-bearing parts of the drainage basins of the two streams contain more garnet, ilmenite, rutile, and sillimanite than concen- trates from the monazite-free parts of the basins (D. W. Caldwell, written commun., 1954). Monazite- free concentrates have more zircon, magnetite, and epidote than concentrates containing monazite. Sedi- ments along Little Beaverdam Creek and Cleveland Creek have less monazite, garnet, and ilmenite, and more epidote and magnetite than sediments on Big Beaverdam Creek upstream from the mouth of Cleve- land Creek. Remnant deposits of gravelly silt lie on an irreg- ular erosion surface about 20 feet higher than the present valley floor on the west side of Big Beaver- dam Creek at two points situated about 1.3 miles northwest of the Oconee County line and 2 miles southeast of the county line. A similar deposit oc- curs on the east side of Little Beaverdam Creek 1.5 miles northwest of the Oconee County line. Heavy- mineral suites from the terrace deposits have less of the unstable minerals and more of the stable minerals than do suites from the present flood plain sediments (table 81). Monazite is one of the minerals whose TABLE 81.—Relative abundance of stable and unstable heavy minerals in terrace gravel and rifle sediments in Big Beaverdam Creek and Little Beaverdam Creek in Oconee and Anderson Counties, S.C’. [Modified from D. W. Caldwell (written commun., 1954). Symbols used: M, terrace gravel has more than present rifl‘le sediment; L, terrace gravel has less than present riflie sediment; Ab, absent in all samples compared; U, unique to sample of terrace gravel; ID, insufiicient data] Big Beaverdam Creek— Little Beaverdam Upstream Downstream Creek from county from county line line Monazite _________________ M M M Ilmenite __________________ M M M Rutile ___________________ U U M Zircon ___________________ L M M Sillimanite __________ _ Ab U Ab Garnet _____________ _ L L L Magnetite __________ _ L L L Amphibole ________________ Ab U Ab Epidote __________________ L ID L 251 relative abundance is increased by the interstratal solution of the unstable heavy minerals. The resources of monazite along Big Beaverdam Creek and Little Beaverdam Creek were estimated by D. W. Caldwell to be about 13,000 short tons in flood—plain sediments having an average tenor of 0.5 pound of monazite per cubic yard (Overstreet, Theo- bald, and Whitlow, 1959, p. 710). Continous flood plains extending upstream along Big Beaverdam Creek from the head of the gorge above the Tugaloo River to the head of the creek, exclusive of sediment in Cleveland Creek, are the richest parts of the area. Alluvium in this valley was estimated by D. \V. Caldwell (written commun., 1954) to contain about 7,500 short tons of monazite and to have an average tenor of 0.9 pound of monazite per cubic yard. unconsommrnn SEDIMENTARY nocxs IN THE COASTAL PLAIN PROVINCE The distribution of monazite in unconsolidated sedimentary rocks in the Atlantic Coastal Plain phys— iographic province of South Carolina is generally poorly known. Practically all published data on the occurrence of monazite in rocks of Cretaceous and Tertiary age are indirect. Measurements of radio- activity of concentrates from grab samples of Cret- aceous and Tertiary sedimentary rocks were made by Lincoln Dryden, and the observed radioactivity was interpreted in terms of monazite in the raw sediment (Dryden, 1958, p. 401—405). Anomalies in natural gamma aeroradioactivity over parts of Saluda, Lexing- ton, Calhoun, Orangeburg, Dorchester, Colleton, Hampton, Allendale, Bamberg, Barnwell, Aiken, and Edgefield Counties were interpreted by Guillou and Schmidt (1960) and by Schmidt (1961; 1962, p. 29—38) as resulting from monazite in residual soil derived from Upper Cretaceous and Eocene strata. These studies indicate that a gradual diminution takes place seaward in the amount of monazite in the Coastal Plain formations. The studies also suggest that monazite in the younger formations was derived from reworked parts of older sedimentary rocks. No place is known in South Carolina where the amount of monazite in the Cretaceous and Tertiary sediments is sufficiently great to form a workable fossil placer. These sedimentary rocks have served as proximate sources from which monazite has been reconcentrated to form Pleistocene and Recent fluvial and littoral placers (Mertie, 1953, p. 12—13; Siple and others, 1959). Highly detailed information on the amount of mon- azite in unconsolidated sediments of Quaternary age has been published for small areas in the South Caro- lina Coastal Plain that were explored for detrital 252 monazite and for one area that was mined. Similar information covering more extensive areas of explora- tion is privately held. DEPOSITS 0F CRETACEOUS AGE The oldest unconsolidated sediments in the Atlantic Coastal Plain in South Carolina are strata of the Tuscaloosa Formation, Black Creek Formation, and Peedee Formation of Late Cretaceous age. The Tus— caloosa rests on crystalline rocks, generally crops out along the inner edge of the Coastal Plain, and dips gently toward the southeast. Toward the southeast the Cretaceous formations are overlain by progres- sively younger sedimentary rocks of Tertiary age. Locally in South Carolina the Tertiary formations are widely transgressive, overlapping older forma- tions and lying directly on crystalline rocks. Thus, in some areas the inner edge of the Coastal Plain is marked by Tertiary sedimentary rocks instead of by beds of Cretaceous age. The Tuscaloosa Formation consists dominantly of silty and clayey sand, commonly pebbly, and asso- ciated pebble beds and lenticular masses of clay. The formation is highly variable, and crossbedding, lens- ing, and channel fillings are exposed in almost every outcrop (Lang and others, 1940, p. 32—43; Dryden, 1958, p. 397). The Black Creek and Peedee Forma- tions are well bedded and more uniform than the Tuscaloosa. The Black Creek consists of very dark gray laminated clay and micaceous sand (Cooke, 1936, p. 25). It rests unconformably on the Tusca- loosa and in South Carolina is unconformably over- lain by the Peedee Formation or younger sedimentary rocks. In South Carolina the Peedee is the youngest of the Cretaceous formations. It is gray sandy marl interbedded with thin layers of hard marlstone (Cooke, 1936, p. 32—33). Typically concentrates from the Cretaceous sedi- mentary rocks consist of about 50 percent ilmenite and leucoxene and, in approximate order of abun- dance, variable quantities of zircon, rutile, monazite, staurolite, kyanite, sillimanite, tourmaline, and spine] (Dryden, 1958, p. 393). Epidote, garnet, and horn- blende are absent despite their common presence in the pre-Cretaceous crystalline rocks. Concentrates prepared by Lincoln Dryden from 151 grab samples from the Tuscaloosa Formation, two samples from the Black Creek Formation, and one sample from the Peedee Formation were examined for radioactivity in the same way that samples from Alabama, Georgia, and North Carolina were processed (Dryden, 1958, p. 411—415). The weight percentage of monazite in the concentrate was interpreted from THE GEOLOGIC OCCURRENCE OF MONAZITE the radioactivity of the concentrate, and for most con- centrates the weight percentage was recalculated to inferred pounds of monazite per cubic yard of sedi- mentary rock. By these procedures, 143 of the 151 samples of Tuscaloosa were inferred to be monazite bearing, both samples from the Black Creek F orma- tion were assumed to contain monazite, and the sam— ple from the Peedee Formation was interpreted to be barren of monazite. The two samples from the Black Creek Formation were inferred to contain 0.01 and 0.1 pound of mona— zite (Dryden, 1958, p. 405). They came from Dillon County at localities respectively southwest and south of the town of Dillon. The amount of monazite in the 143 monazite— bearing samples of the Tuscaloosa Formation was estimated by Dryden (1958, p. 401—405) to range from 0.01 to 1.68 pounds per cubic yard and to aver- age 0.24 pound per cubic yard (table 82). The sam- ple showing 1.68 pounds of monazite per cubic yard came from a locality just south of the city of Chester- field, Chesterfield County, in an area where several samples seem to have about twice as much monazite as the regional average for the Tuscaloosa. The amount of monazite in the sedimentary rocks was thought by Dryden to be uninfluenced by the grain size of the sediments, and he presented evidence to Show that coarse sands are not notably enriched in monazite (Dryden, 1958, p. 419). Radioactivity in the Tuscaloosa Formation was, however, found by Schmidt (1962, p. 36) to be notably greater in grav- elly layers, particularly in basal gravel, than in the formation as a whole. Inasmuch as the radioactivity is attributed mainly to monazite, it would seem that Schmidt’s observations discount the conclusion reached by Dryden that the amount of monazite is unrelated to the size of particles in the sediment. TABLE 82.—Inferred amount of monazite in the Tuscaloosa For- mation in South Carolina [Modified from Dryden (1958, p. 401—405)] Inferred tenor (lb per Numfber cu yd) 0 samples Min Max Avg Vicinity of Dillon, Dillon County .............. 1 ________________ 0. 01 Vicinity and north of Bennettsville, Marlboro County ______________________________________ 22 0. 01 1. 25 . 21 South of Chesterfield, Chesterfield County ..... 45 . 01 1. 68 . 28 Flat Creek area, Lancaster County.-. .... 4 02 .50 . 18 Ridgeway, Fairfield County __________ 1 ________________ .08 South of Camden, Kershaw County._ 25 .01 .93 .30 Darlington County ___________________ 4 . 01 . 48 . 15 Vicinity of Lucknow, Lee County. 2 .3 . 68 . 49 Western part of Sumter County. . . 2 . 08 . 1 . 09 Richland County __________________ ..__ 14 . 03 . 65 . 26 Lexington County ................. -__. 10 . 03 .88 .36 Aiken County _________________________________ 13 . 01 .45 . 13 Average .................................. 143 ................ . 24 SOUTH CAROLINA Regional variations in the amount of monazite in the Tuscaloosa Formation were attributed by Dryden (1958, p. 421—422) to original abundances of mona- zite in source areas from which the sediments were derived. He suggested that parts of the formation having greater than average amounts of monazite possibly came from broad and rich segments of the monazite belt in the western Piedmont. For most areas in South Carolina this assumption seems to be correct, but for one area another explanation may fit the observations a little better. Samples having indicated tenors of about 0.5 pound of monazite per cubic yard and several samples hav- ing more than a pound per cubic yard, including the richest sample from the Tuscaloosa in South Caro- lina, were obtained by Dryden (1958, p. 421) from an area in northern Marlboro County and part of Chesterfield County in the present drainage basin of the Pee Dee River. The source of this above-average Tuscaloosa Formation was speculatively suggested by Dryden to have been the western belt of monazite- bearing rocks. Because the drainage leading to Marl- boro County and Chesterfield County comes by way of the Yadkin River from a narrow and low—tenor part of the western belt, Dryden offered the explana- tion that in Tuscaloosa time a more easterly system of drainage brought monazite from richer and wider parts of the belt southwest of the segment now reached by the Yadkin. Had these relations existed, however, it would seem that more samples of the Tuscaloosa in Marlboro County and Chesterfield County should have above~average tenors. Actually the averages for the two counties are little different from the regional aver- age. Possibly this area of above-average tenor received its sedimentary debris from a much nearer, but rela- tively small, source in monazite-bearing crystalline rocks. It is here suggested that the source may have been an unreported body of monazite-bearing rock in a projection of the eastern monazite belt of Mertie (1953, pl. 1). If the trend of the eastern belt is extended, it is found to pass close to the area of high-tenor samples in Marlboro County and Chesterfield County. A small local source in this extension, now possibly buried under Tuscaloosa Formation, might more satisfactorily ac- count for a few high-tenor samples than a large, distant source. The Tuscaloosa Formation in the area between Ches- terfield County and Columbia in Richland County was the source of four samples having rather high amounts of monazite and was the source of 50 samples lean in monazite (Dryden, 1958, pl. 20). Included among the high-tenor samples were three from Kershaw County 253 in the vicinity of Camden: a sample having 0.68 pound of monazite taken just southeast of Camden, one having 0.93 pound of monazite collected near Lugofi', and one having 0.88 pound of monazite from a point between Lugoff and Blaney. The fourth high-tenor sample came from Richland County at a locality about 10 miles east of Columbia. It contained an estimated 0.65 pound of monazite per cubic yard. The general pat— tern of low-tenor samples between Richland County and Chesterfield County indicates that no very rich source of monazite was available to the streams which deposited this part of the Tuscaloosa Formation. At present the drainage into this area just reaches the northeastern segment of the core of the western mona— zite belt, and mostly it does not cross known monazite- bearing rocks in the eastern belt except in the vicinity of Columbia (Mertie, 1953, pl. 1). Evidence is not very clear as to the probable source of the monazite, but it seems to favor Dryden’s interpretation that the monazite was brought from the western belt. The Broad River and Saluda River join at Colum— bia to form the Congaree River which, about 35 miles downstream, is entered from the north by the VVateree River. Below this junction the stream flows to the Atlantic Ocean and is known as the Santee River. Drainage basins of the Broad River and Saluda River encompass most of the core of the western monazite belt and are underlain by the greatest area of mona- zite-rich crystalline rocks of any streams in the Pied— mont. This system of drainage doubtless does not exactly match drainage patterns active in Tuscaloosa time; however, the fact that sedimentary rocks of the Tuscaloosa Formation exposed at and southwest of Columbia are richer in monazite than average Tusca- loosa in the State may indicate a similar drainage pattern in the past (Dryden, 1958, p. 442). Doubt— less most of the monazite in this part of the forma- tion was derived from the core of the western belt, but some is locally derived from granitic rocks imme— diately underlying the Tuscaloosa, a condition appar- ently observed by Schmidt (1962, p. 35—36) at Long Creek, which is a tributary to Twelvemile Creek in Lexington County, and near McTier Creek in north- ern Aiken County. There the base of the Tuscaloosa is composed of very radioactive gravelly sand con- taining small angular pebbles of blue-gray quartz similar to vein material in underlying granite. The granite was less radioactive than the gravel, but it was very likely the source of monazite in the gravel. The sedimentary rocks in the Tuscaloosa Formation exposed south and southwest of Columbia were ob- served by Dryden to be richer in monazite than ex- 254 posures of the formation elsewhere in the State. Tenors between 0.40 and 0.88 pound of monazite per cubic yard were estimated by Dryden (1958, pl. 20) for four samples of the Tuscaloosa in Lexington County, and the average tenor of 10 samples from the county is about 50 percent greater than the State average for the formation (table 82). These esti- mates are supported by the results of a natural gamma aeroradioactivity survey of this part of South Caro- lina (Schmidt, 1961). Areas underlain by Tusca- loosa Formation in Lexington County and northern Aiken County were found by Schmidt to be much higher in radioactivity than Tuscaloosa exposed far- ther south and west in Aiken County (Schmidt, 1962, p. 36). Seemingly, the greatest concentration of monazite now known in the Tuscaloosa Formation is in and west of the area presently reached by the Broad River and Saluda River. Possibly an earlier system of drainage from the core of the western monazite belt emptied at this part of the Tuscaloosa strand and deposited most of the monazite present in the formation. Good evidence shows that the amount of monazite in the Tuscaloosa Formation declines southward across Aiken County and continues to decline in Georgia. This decline is shown by the estimates of tenor prepared by Dryden (1958, p. 404—405), where it is seen that the average tenor for the county is only 0.13 pound of monazite per cubic yard, in contrast to the State average of 0.24 pound (table 82). The de— cline is also indicated by the map of aeroradioactivity, which shows that the formation gave 7 00—1,300 counts per second in Lexington County and northern Aiken County but only 400—700 counts per second elsewhere (Guillou and Schmidt, 1960, p. B120; Schmidt, 1961). Other writers have also indicated that the Tusca- loosa Formation in Aiken County is lean in monazite. Concentrates from several test wells in clay deposits in the formation were examined by W. B. Lang in the 1930’s, but monazite was found in only one (Lang and others, 1940, p. 35). It came from a well 1.5 miles south of Langley on the south side of Horse Creek. The monazite occurred in material 45—46 feet below the collar of the well. In this interval the material contained a mixture of 7 5-80 percent of mica and 20—25 percent of white clay and quartz with some staurolite, tourmaline, zircon, sillimanite, mona— zite, ilmenite, and magnetite. White sand and clay of the Tuscaloosa Formation in the bed of Holley Creek were said by Kline, Griflith, and Hansen (1954, THE GEOLOGIC OCCURRENCE OF MONAZITE p. 10) to be relatively free of heavy minerals and to contain but scant monazite. DEPOSITS OF TERTIARY AGE The Tertiary sedimentary rocks in the Coastal Plain of South Carolina unconformably overlie formations of Cretaceous age and locally transgress onto pre-Cretaceous crystalline rocks. The Tertiary formations dip gently southward and strike eastward (Cooke, 1936, pl. 2). They are extensively mantled by very gently dipping deltaic, estuarine, or marine nearshore deposits of Pleistocene age. Seven Tertiary formations are described in South Carolina (Cooke and MacNeil, 1952, p. 20), but only four have as yet been reported to be monazite bearing. These are the Black Mingo Formation of the Wilcox Group, the Congaree Formation and the McBean Formation of the Claiborne Group, and the Barnwell Formation of the Jackson Group. The nomenclature used by Cooke (1936, pl. 2) on his map of the Cretaceous and Tertiary formations of South Carolina was revised by Cooke and Mac- Neil (1952, p. 21—24) in a discussion of Tertiary stratigraphy of the State. Cooke and MacNeil intro— duced the term “Congaree Formation” for deposits of early Claiborne age in South Carolina, which had theretofore been mapped as McBean Formation, and they stated that a large part of the sedimentary rocks previously mapped as Barnwell Sand of Cooke proved upon reinvestigation to be Congaree also. Inasmuch as the revised terminology was not accompanied by a new map to show the effect of the change, it is not possible to relate the sparse data on monazite to the new terminology. In the following review the mona- zite—bearing sample localities are referred to Cooke’s geologic map of 1936, on which the Black Mingo Formation, McBean Formation, and Barnwell Sand of Cooke are referred to the Eocene. The Black Mingo Formation of Cooke (1936, p. 41) is made up of gray to black brittle clay or shale, sandy shale, and sand. The McBean Formation of Cooke (1936, p. 56) consists mainly of fine to medium sand and thin beds of glauconitic marl, clay, and limestone. The Barnwell Sand of Cooke (1936, p. 89—90) trans- gresses northward unconformably over older forma- tions and consists principally of fine to coarse reddish pebbly sand and massive orange sand. Because the McBean and Barnwell of Cooke are widely monazite bearing, it is here inferred that the Congaree Forma— tion of Cooke and MacNeil also contains monazite. SOUTH CAROLINA Concentrates from these formations were reported to consist of dominant ilmenite and leucoxene with which are associated variable amounts of zircon, rutile, monazite, staurolite, kyanite, sillimanite, and tourmaline (Dryden, 1958, p. 393). A sample from an exposure of the Black Mingo Formation of Cooke was estimated by Dryden (1958, p. 405) to contain 0.17 pound of monazite per cubic yard. The exposure is about 4 miles north of Eastover in Richland County. Amounts of monazite from five samples from the McBean Formation of Cooke were inferred by Dryden (1958, p. 405) to have the following tenor: Tenor (It Calhoun County: ‘geTZLWfi‘,’ Near Beaver Creek ___________________________ 0. 83 Lexington County: North of Swansea _____________________________ . 48 Bull Creek south of Swansea ___________________ 1. 73 Orangeburg County: North Fork Edisto River near North ____________ . 43 Aiken County: Near Salley __________________________________ . 02 Average ___________________________________ . 70 The high average tenor was attributed by Dryden (1958, p. 424) to concentration of the monazite in the lower part of the McBean by the reworking of materials from the Tuscaloosa. Dryden inferred that high tenors might be expected to persist laterally for considerable distances near the contact between the two formations owing to the regularity of bedding in the McBean. Possibly the monazite content of the McBean tends to be more regular than the grab samples show. The Bull Creek locality south of Swansea in Lexington County, where a very high—tenor sample was taken by Dryden, is in an area of moderately high natural radioactivity, giving 500—700 counts per minute (Schmidt, 1961, map). An almost identical radio- activity was measured over the Salley area in Aiken County, where a sample from the McBean was esti- mated to contain only 0.02 pound of monazite. Surface sampling by the U.S. Bureau of Mines of the McBean Formation of Cooke exposed on ridges in the vicinity of Holley Creek and Town Creek in Aiken County was said to have shown fair to good concentra- tions of monazite, but the tenors of the samples were not reported (Kline and others, 1954, p. 14—45). The Barnwell Sand of Cooke was sampled at 14 localities in South Carolina by Dryden (1958, p. 405). He estimated that these samples contained from 0.01 to 1.87 pounds of monazite per cubic yard and averaged 0.33 pound: 255 Tenor (It Lexington County: $3373 Near Edmund ________________________________ 0. 48 South of Edmund _____________________________ . 13 Aiken County: Near Wagener ________________________________ . 28 South Fork Edisto River east of Aiken __________ 1. 87 . 83 8 miles east of Aiken ______________________ . 18 4 miles east of Aiken ______________________ . 28 5 miles‘north of Aiken _____________________ . 05 8 miles northeast of Aiken _________________ . 16 South of Eureka ______________________________ . 23 Eureka ______________________________________ . 13 Edgefield County: Vicinity of Trenton ___________________________ . 01 East of Johnston _____________________________ . 04 Saluda County: Ridge Spring _________________________________ . 05 Average ___________________________________ . 33 The sample having the highest tenor was collected In Aiken County at an exposure on the South Fork Edisto River about 11 miles east of the city of Aiken, in an area of low to intermediate radioactivity (Schmidt, 1961). In the area around Holley Creek and Town Creek, Aiken County, surface samples were said to have indicated fair to good concentrations of monazite in the Barnwell Sand of Cooke, but the tenors were not specifically reported (Kline and others, 1954, p. 14— 15). Surface materials in the Holley Creek—Town Creek area are generally low in natural radioactivity (Schmidt, 1961). Dryden (1958, p. 422) reported that the area he sampled adjacent to the Savannah River and southward was about the leanest in mona- zite of any parts of the State that he examined. The apparent conflict between the statements of Kline, Griffith, and Hansen and the observations of Schmidt and Dryden probably results from lack of regional background for comparison in the report by Kline and associates. There is no obvious reason to believe that the formations in the Holley Creek—Town Creek area are significantly richer in monazite than the same formations elsewhere in the State. Evidence has been presented to show that they are not. Such evidence clearly indicate that equal or richer fluvial placers may be present in valleys northeast of Aiken County in the Coastal Plain in Lexington County and Richland County. MARINE TERRACE PLAINS OF PLEISTOCENE AGE Thin marine deposits of Pleistocene age form ter- race plains that extend inland for distances of 80 or 256 90 miles from the present coast of South Carolina (Cooke, 1936, p. 5—9, 130—154). They occupy about two-thirds of the area of the Coastal Plain. At many places the inner margin of the Pleistocene marine deposits is rather obscure owing to erosion of the highest terrace and to lack of relief between the ter- race and the other sedimentary rocks inland from it. The terrace plains were interpreted by C. W. Cooke to have been formed by marine wave action in a suc— cession of advances and retreats of the sea during the Pleistocene epoch. According to Cooke’s concept the coastal region was warped downward at the close of Pliocene time and inundated by the sea as far inland as the highest and oldest terrace, which is found at an altitude of 270 feet above present sea level. Wave action along the shoreline of maximum advance created wave-cut and wave-built features of which remnants are still preserved. As the sea re- treated the exposed plain was eroded. A new ad- vance of the sea reached less inland, and another line of wave-formed features defined a second shore at an altitude of about 215 feet. Fresh layers of clay, sand, and gravel were deposited and covered the flooded part of the plain. Another retreat of the sea followed by other advances and retreats led to the formation of seven shore lines during the Pleistocene epoch. Remnants of these features are preserved at approx- imately the following heights, in feet, above present sea level: 270, 215, 170, 100, 70, 42, and 25 (Cooke, 1936, p. 130). Seven formations corresponding to the seven high stages of the sea were recognized in South Carolina by Cooke (1936, p. 130—154). The inland edge of each formation was the shore of the sea and its estuaries at the given height. The seaward edge of the formation is taken as the shoreline of the next younger formation, and the surface of the formation is a terrace or plain between the defining shores. Names of the formations from oldest to youngest and approximate altitudes of the shorelines were given by Cooke (1936, p. 130): Altitude Formation (feet) Brandywine ________________________________ 270 Coharie ____________________________________ 2 1 5 Sunderland ________________________________ 1 70 Wicomico __________________________________ 1 00 Penholoway ________________________________ 70 Talbot ____________________________________ 42 Pamlico ___________________________________ 25 These Pleistocene formations are composed mainly of sand and clay. The sand tends to be finer in the younger formations than in the older formations and was thought by Cooke to have been washed out of older formations by currents that were too weak to THE GEOLOGIC OCCURRENCE OF MONAZITE transport coarse-grained debris. Very little sedi- mentary material was carried as far out to sea as the present coast; hence, deposits of pre-Pleistocene age are exposed near the present shore, and the Pleistocene formations in South Carolina are nowhere very thick. Cooke’s ideas have subsequently been challenged by Flint (1940, p. 757—785), Mertie (1953, p. 13-15), and others, and detailed work in the early 1960’s in parts of South Carolina indicated that some revision in interpretation was needed (Colquhoun, 1962). In a review of the literature and a report on reconnais- sance study of the Pleistocene sediments and surface features of the Atlantic Coastal Plain, Flint (1940, p. 757—785) concluded that the seven strandlines rec— ognized by Cooke were not certainly demonstrated and that the deposits up to an altitude of at least 100 feet formed under marine conditions. Flint thought that at least two former shorelines were dis- tinctly recognizable. The Pleistocene terrace plains were thought by Mertie (1953, p. 13—15) to have received terrigenous sediments, mainly deltaic and estuarine deposits, which were laid down over older sediments that had been reworked by the sea. Ocean currents and waves did not generally affect the terrigenous sediments. In Mertie’s opinion the coast was under more or less continuous epeirogenic uplift throughout the succes- sive glacial and interglacial oscillations of the sea. In the absence of strong littoral sorting, beach plac- ers failed to form. Colquhoun’s observations indicate a very complex interrelation between fluvial and marine deposition of the Pleistocene formations (Colquhoun, 1962, p. 73—75). None of this work has led to a revised map of the Pleistocene formations in South Carolina, and until such a map is available, reference will continue to be made to Cooke’s map (1936, pl. 1). Sediments at the present land surface of the Pleisto- cene marine terrace plains are lean in monazite. The amount of monazite in Coastal Plain formations of Pleistocene age in Georgia and South Carolina was reported by Mertie (1953, p. 15) to range from less than 1 to 9 percent of the concentrate, with concentrates making up only 0.01—0.1 percent of the sedimentary rock. Pleistocene formations in Calhoun, Orangeburg, Dorchester, Colleton, Bamberg, Barnwell, Allendale, and Hampton Counties, S.C., were found by Schmidt (1962, p. 35—38) to have less radioactivity than older deposits on the Coastal Plain. Dryden (1958, p. 406, pl. 20) examined 18 concentrates from Pleistocene sediments in the State and observed monazite in 17. The inferred average tenor was only 0.19 pound of SOUTH CAROLINA monazite per cubic yard. When the locations of the 18 samples are plotted on Cooke’s (1936, pl. 1) map of the Pleistocene deposits, it is seen that 11 samples came from formations in the marine terrace plains or estuarine extensions up the valleys of major streams, and 7 came from outlying deposits on old formations in the Coastal Plain northwest of the Brandywine terrace. Samples from the marine terrace plains have a low inferred average tenor of 0.11 pound of monazite per cubic yard, whereas samples from outlying areas northwest of the Brandywine terrace contain nearly three times as much monazite: Tenor (lb of monazite per cu yd) Marine terrace plains and estuarine deposits Marlboro County: Brandywine Formation north of Bennettsville ______ 0. 13 Penholoway Formation south of Bennettsville ______ . 21 Wicomico Formation south of Bennettsville ________ . 05 Dillon County: Wicomico Formation east of Dillon _______________ . 00 Wicomico Formation southwest of Dillon __________ . 05 Florence County: Penholoway Formation southeast of Florence _______ . 10 . 21 Chesterfield County: Wicomico Formation southeast of Chesterfield _____ . 02 Darlington County: Coharie Formation northwest of Hartsville _________ . 08 Kershaw County: Brandywine Formation southeast of Camden _______ . 16 Richland County: Coharie Formation at Columbia __________________ . 25 Average _____________________________________ . 11 Pleistocene sediments northwest of the Brandywine terrace Chesterfield County: Southwest of Chesterfield ________________________ 0. 18 . 38 Lexington County: West of Edmund _______________________________ . 45 Southwest of Edmund ___________________________ . 03 Aiken County: Near Eureka ___________________________________ . 33 North of Aiken _________________________________ . 13 East of Aiken __________________________________ . 55 Average _____________________________________ . 29 Average, all samples __________________________ 0. 19 The mineralogical composition of concentrates from the Pleistocene deposits was said by Dryden (1958, p. 393—394, 424) to resemble the composition of con- centrates from Cretaceous and Tertiary formations in that they lack epidote, garnet, and hornblende. They commonly consist of 50 percent or more of ilmenite and leucoxene and variable percentages of 238413—67—18 257 other minerals. In approximate order of average abundance the minerals are zircon, rutile, monazite, staurolite, kyanite, sillimanite, tourmaline, and spinel. At several places, pairs of samples from the Tuscaloosa Formation and overlying Pleistocene deposits were collected by Dryden, and the samples in a pair from a given locality were usually found to be very similar in tenors in monazite. This similarity was interpreted by Dryden to suggest that in these pairs of samples the sedimentary material of Pleistocene age was composed largely of reworked Tuscaloosa Formation. Concentrates from alluvium in Coastal Plain reaches of trunk streams rising in the Blue Ridge or Piedmont contain epidote, garnet, and hornblende along with the other minerals found in Coastal Plain sediments (Dryden, 1958, p. 393—394). Epidote, gar— net, and hornblende are also present in concentrates from the present beaches. The evidence does not show with certainty whether these minerals are absent in the Pleistocene deposits because the deposits were de- rived mainly from old formations devoid of epidote, garnet, or hornblende, or whether these minerals have weathered out of the Pleistocene sediments since they were deposited. In the Piedmont of South Carolina, however, Pleistocene alluvium of pre—Wisconsin age displays only barely perceptile reduction in epidote, garnet, and hornblende owing to weathering after deposition (D. W. Caldwell, written commun., 1954). To the writer the absence of these three minerals in the Pleistocene deposits most likely indicates that the Pleistocene sediments were mainly derived from Cretaceous and Tertiary formations. The higher tenor in monazite of the Pleistocene deposits northwest of the Brandywine terrace com- pared to tenor in monazite of Pleistocene sediments southeast of the terrace coincides with observed sea- ward decrease in radioactivity of surface materials in the Coastal Plain. Such distribution in tenor seems more to be expected from sedimentary processes as interpreted by Cooke than from processes as inter- preted by Mertie. The absence of epidote, garnet, and hornblende from Pleistocene sediments on marine terrace plains also fits well with Cooke’s ideas but not with those of Mertie. Until systematic and de- tailed studies of these deposits are made, however, the sedimentary processes remain uncertain. Detailed studies are also needed before a correct evaluation can be made of possible placer deposits of monazite and other heavy minerals in the Pleistocene formations. No accounts have been published of heavy minerals in the spits, islands, and other depositional features 258 strikingly shown by Cooke (1936, pl. 1) on marine terrace plains underlain by the Pamlico, Talbot, Pen- holoway, and Wicomico formations in South Caro- lina. Obviously such features need to be thoroughly examined before the possibility of workable placers can be evaluated. Placers workable for monazite alone, however, are not to be expected, although ilmenite deposits from which monazite might be re- covered as a byproduct are a possibility. STREAM SEDIMENTS 0F QUATERNARY AGE Sediments in the valleys of the present streams of the Coastal Plain are Quaternary in age. Major streams entering the Coastal Plain from the Piedmont were depicted by Cooke (1936, pl. 1) to have along their valleys various flood-plain and terrace deposits related to Pleistocene formations he recognized on the marine terrace plains. Rivers rising on the'Coastal Plain are shown as occupying valleys filled wit-h Pleis- tocene formations appropriate for the altitudes reached by the flood plains. Valleys of streams rising in the Coastal Plain derive their fill from adjacent unconsolidated sediments, but valleys of trunk streams seem to have gotten their sediments chiefly from the Piedmont and Blue Ridge and did not receive much from the Coastal Plain (Dryden, 1958, p. 425). Suites of heavy minerals from valley deposits along streams rising in the Coastal Plain lack the notable amounts of epidote, garnet, and hornblende present in concentrates from sediments in the Coastal Plain segments of the valleys of trunk streams rising in the Blue Ridge or Piedmont (Kline and others, 1954, p. 17; Dryden, 1958, p. 425). If interstratal solution had removed the less stable minerals in the Pleisto— cene formations on the marine terrace plains, then solution should have been equally effective in remov- ing the same kinds of minerals in sediments in the valleys of trunk streams providing that the sediments in the main valleys are time equivalents of formations on the terrace plains. Monazite-bearing concentrates were panned in the late 1940’s by Mertie (1953, pl. 1, p. 15) from Ed;— ments in streams on the Coastal Plain of South Carolina. The amount of monazite was reported to be small, being 1—9 percent of concentrates that constituted only 0.01—0.1 percent of the sediment, but monazite was present in 36 out of 38 samples. If the locations of Mertie’s samples are compared to the Pleistocene forma- tions as shown by Cooke (1936, pl. 1), it is seen that THE GEOLOGIC OCCURRENCE OF MONAZITE each of the Pleistocene formations was the proximate source of some monazite—bearing stream sediment: Number of monazite- bearing samples of stream County Formation sediment Calhoun ________________ Sunderland ____________ 2 Brandywine ___________ 1 Clarendon ______________ Wicomico _____________ 1 Orangeburg _____________ Wicomico _____________ 1 Sunderland ____________ 5 Coharie _______________ 3 Brandywine ___________ 1 Dorchester ______________ Pamlico _______________ 2 Wicomico _____________ 1 Sunderland ____________ 1 Berkeley ________________ Pamlico _______________ 2 Talbot ________________ 3 Penholoway ___________ 2 Charleston ______________ Pamlico _______________ 1 Talbot ________________ 1 Georgetown _____________ Pamlico _______________ 3 _ Talbot ________________ 4 Williamsburg ____________ Penholoway ___________ 2 Total ____________________________________ 36 The Calhoun County localities are on tributaries to Halfway Swamp. In Clarendon County, monazite was found in a small stream between Jacks Creek and the Santee River. Cooper Swamp and streams west to the South Fork Edisto River in southwestern Orange- burg County were shown by Mertie to contain mona- zite, and in the eastern part of the county, monazite was present in concentrates from tributaries to Four Hole Swamp, Sandy Run, and the Santee River. Streams in Dorchester County that were sources of monazite-bearing concentrates are Cattle Creek, Four Hole Swamp, and the Ashley River. In Berkeley County, monazite was found along Cypress Swamp, Back River, Biggin Swamp, East Branch, and short tributaries to the Santee River. Tributaries to Goose Creek and the Wando River in Charleston County yielded monazite, as did the Sampit River and tribu- taries to the Black River in Georgetown County. Farther upstream along the Black River, tributaries in VVilliamsburg County also were the source of monazite- bearing concentrates. Present sediments in the valley of Rocky Creek about 5 miles west-northwest of Lexington in Lexing- ton County were reported by Mertie (1953, p. 13) to contain about 0.5 pound of monazite per cubic yard. Granite exposed in the bed of the stream is devoid of monazite; thus, Cretaceous or Tertiary formations overlying the granite are the probable source of the monazite. Sediments in the valleys of’streams around Aiken in Aiken County were found to be monazite bearing by SOUTH CAROLINA Mertie (1953, p. 13) during the course of work in the summer of 1951. Toward the close of the year interest began to develop in these deposits, particularly in those on Holley Creek, Town Creek, and Horse Creek. A program to evaluate placers along the valleys of Holley Creek and Town Creek and the Holley Creek delta in the valley of the Savannah River was begun by the U.S. Bureau of Mines in December 1951 (Kline and others, 1954, p. 4—5). The valleys of Holley Creek and Town Creek were estimated, on the basis of results from 21 widely spaced churn—drill holes out of 45 sunk, to contain 66 million cubic yards of alluvium having about 40,000 short tons of monazite (Kline and others, 1954, p. 6): Tenor (lb of Reserves monazite per (1,000 short on yd) tons) Monazite _____________________________ 1. 2 1 40 Rutile ________________________________ 1. 67 55 Zircon ________________________________ 1. 99 66 Ilmenite ______________________________ 4. 82 160 Staurolite _____________________________ 6. 40 212 Kyanite ______________________________ . 73 24 The potential placer ground has an area of about 2,230 acres and an average depth of 18.4 feet. The base of the placer is a relatively barren white sand and clay at depths ranging from 10 to 40 feet below the surface of the flood plain. Total length of the placer area along both streams is 16 miles, and throughout this length the flood plains range in width from 225 to 3,300 feet. Throughout their length the streams were reported to flow on sedimentary rocks of the Tuscaloosa Forma- tion (Kline and others, 1954, p. 11—13), but the promi- nent ridge between Holley Creek and Town Creek is capped by the McBean Formation, and a few miles to the south of the two streams the McBean and Barn- well Formations cover the Tuscaloosa. Pleistocene terraces are present in the valleys from the Brandywine terrace at an altitude of 270 feet to the Wicomico at an altitude of 100 feet, and blown sand covers the ridges and forms dunes locally. Spot samples of the Tus- caloosa, McBean, and Barnwell Formations by Kline, Griflith, and Hansen (1954, p. 14—15), supported by ear- lier reports on heavy minerals in wells in these forma- tions (Lang and others, 1940, p. 32—40) show that monazite is more abundant in this area in the McBean and Barnwell Formations than in the Tuscaloosa. It is inferred that the Tuscaloosa is less important as a source for monazite in Holley Creek and Town Creek than is the McBean and Barnwell. They also postu- late that Holley Creek is actively degrading and that erosion is more conducive to the formation of fluvial placers than rapid aggradation. Alluvium in Holley Creek upstream from the valley of the Savannah River was said to give concentrates 259 with a restricted suite of heavy minerals consisting of the most stable species, whereas concentrates from alluvium in the flood plain of the Savannah River at the mouth of Holley Creek contain a striking display of unstable minerals (Kline and others, 1954, p. 16— 17 ). In Holley Creek proper, epidote is present in only trace amounts, as are magnetite and garnet, but in the delta of Holley Creek on the flood plain of the Savannah, epidote makes up 15 percent of the concen- trate, and magnetite and garnet are even more abun- dant. Zircon, monazite, rutile, and staurolite are much more common in concentrates from the valley of Holley Creek than they are in concentrates from the Savannah River flood plain. About equal amounts of ilmenite, kyanite, and tourmaline are in concentrates from the two sources. The composition of concen- trates from each area shows the general relations (table 83). The suite of heavy minerals in the delta of Holley Creek has been influenced by unstable minerals added from the distributive province of the Savannah River. TABLE. 83.—-—Mineralogical composition, in percent, of monazitr- bearzng concentrates from Holley Creek and the Savannah River, Aiken County, S C [Modified from Kline, Griffith, and Hansen (1954, p. 17). Symbol used: n.d., no data] Holley Creek and Town Savannah Holley Creek Creek (field ivcr (single hole) composite con- (single hole) centrate from 24 holes) Monazite _________________ 4. 3 5. 8 2. 2 Xenotime ________________ . 4 n.d. . 2 Epidote ____________________________ n.d. 15. 2 Hornblende _______________ Trace n.d. 6. 3 Garnet _____________________________ n.d. 2. 1 Ilmenite __________________ 27. 5 22. 0 48. 8 Magnetite ____________ . 1 __________ 3. 8 Quartz-- __________ 16. 0 20. 0 17. O Zircon- - __________ 12. 0 9. 0 2. 8 Rutile---- ____________ 9. 8 8. 0 2. 5 Kyanite __________________ 2. 0 3. 5 __________ Staurolite ________________ 25. 5 30. 0 __________ Tourmaline _______________ . 2 1. 5 __________ Total ______________ 97. 8 99. 8 100. 9 Chemical analyses by the U.S. Bureau of Mines of monazite separates from the Holley Creek area show 5.08 percent of ThOz and 0.54 percent of U308 (Kline and others, 1954, p. 18—20; Kauifman and Baber, 1956, p. 6). The area was said by the Bureau to be suited to mining by either bucket-line or suction dredge. Estimated value of the total product based on prices of January 1954 was $0.40 per cubic yard for the heavy minerals and $0.19 for the gravel (Kline and others, 1954, p. 28). The first large—scale mining of fluviatile placers for monazite and other heavy minerals in the Carolinas 260 was begun in June 1955 by Marine Minerals, Inc., on Horse Creek about 10 miles southwest of Aiken in Aiken County (Lenhart, 1.956, p. 62—63) . Horse Creek is the next major tributary to the Savannah River upstream from Holley Creek, and in many respects the deposit resembles the placers on Holley Creek and Town Creek, except that parts of the valley of Horse Creek and its western tributaries reach granitic rocks that underlie the Tuscaloosa and younger formations. Most of the valley is eroded in the sedimentary rocks near the inner edge of the Coastal Plain, but the main stream above Graniteville and the head of Little Horse Creek expose crystalline rocks (Schmidt, 1962, p. 36). The valley of Horse Creek has been described as a semiswamp covered with trees and brush and inter- rupted locally by old dams. The company was re- ported to have 18—20 million cubic yards of dredging ground on which it located a 6-cubic-foot bucket-line dredge capable of digging to a depth of 35 feet, but most heavy minerals occur at a depth of about 20 feet or less (Lenhart, 1956, p. 63). Another report dating from the early days of the operation stated that the dredge could mine about 2 million cubic yards of sedi- ment a year of which about 1 percent was heavy sand (Crawford, 19580, p. 1156). The heavy sand was reported to be practically free of magnetite (Lenhart, 1956, p. 63—66). Five indus- trial minerals—monazite, rutile, ilmenite, zircon, and staurolite—were separated from the dredge concentrate in a dry plant on shore, and cleaned and screened sand and gravel were produced through an affiliated com- pany. Actual output at Horse Creek is not known, but if the tenor in monazite at Horse Creek is on the same order as at Holley Creek, and 20,000—30,000 short tons of concentrate were produced per year, then the placer may have yielded about 1,200—1,500 short. tons of mona- zite per year. Mining ceased in 1959. Monazite from Horse Creek was analyzed by the US. Bureau of Mines and was reported to contain 5.07 percent of T1102 and 0.51 percent of U308, quan— tities almost identical to those in monazite from Holley Creek (Kaufl‘man and Baber, 1956, p. 6). Placers on Shaw Creek and the South Fork Edisto River in Aiken County were regarded by Perry (1957, p. 4) to equal in size and quality the Horse Creek deposit, but volumes and tenors were not described. Monazite placers were reported by H. S. Johnson, Jr. (oral commun., 1959) to have been found on McTier Creek in northern Aiken County, and an aeroradioactivity high was measured over the area. Sand in McTier Creek was said to contain 1 percent of heavy minerals in which as much as one-third was THE GEOLOGIC OCCURRENCE OF MONAZITE monazite. Granite and sediments of the Tuscaloosa Formation exposed in the valley are monazite bearing (Schmidt, 1961). Traces of monazite were reported by Shufflebarger (1958) to be in mineralogically complex concentrates from flood-plain sediments of the Wateree River south of Camden, Kershaw County. Both banks of the river for a distance of about 8 miles upstream from Sumters Landing are composed of sand, silt, clay, and organic matter which ranges in depth from 8 to 20 feet and contains from grass roots to bedrock an average of somewhat less than 1 percent of heavy minerals. The amount of heavy minerals was said to increase with increasing degree of coarseness of the sediment. Coarse and medium sand has from 4.1 to 14.2 percent of heavy minerals, and the silts and clay have from less than 0.1 to 3.4 percent. Ilmenite, epidote, hornblende, garnet, kyanite, staurolite, and tourmaline are the most common minerals. A little magnetite is present, and rutile, zircon, and monazite occur as traces. COASTAL ISLANDS AND BEACHES At many places along the South Carolina coast, monazite and other industrial minerals have been noticed, and at a few places, notably in the extreme southern part of the State, extensive drilling has been undertaken and the results published. Placer mining, however, has not been started. Reported occurrences of monazite on the coastal islands and beaches are summarized, starting in the northeast. Sand along the shore and in dunes at Myrtle Beach, Horry County, was said to be monazite bearing (Jones, W. H., 1949a, p. 458). Concentrations of heavy miner- als form black layers in the dunes. Natural concentrates containing 80 percent or more of heavy minerals have been formed by wave and wind action on the islands of the South Carolina coast (Neiheisel, 1958a, p. 1). The concentrates range in length from 1 to 5 miles, in width from 20 to 150 feet, and in thickness from 3 inches to 3 feet. In order of decreasing abundance of heavy minerals the deposits are Bull Island, Capers Island, Isle of Palms, Edisto Island, Fripp Island, Dewees Island, and Hilton Head Island. Concentrates from these islands contain an average of 55 percent of ilmenite, 3 percent of rutile, 4 percent of leucoxene, 8 percent of zircon, and 1 percent of monazite accompanied by epidote, hornblende, staurolite, kyanite, garnet, tourmaline, and several other minerals in minor amounts. At Bull Island, Charleston County, beds of black sand consisting of 80 percent heavy minerals were reported to be 1—3 feet thick and to have an average width of 70 feet over a stretch of backshore beach 3 SOUTH CAROLINA miles long (Neiheisel, 1958a, p. 1—3). This deposit was estimated by Neiheisel to contain 150,000 short tons of heavy minerals composed of 63 percent of ilmenite, 2 percent of rutile, 4 percent of leucoxene, 10 percent of zircon, and 1.5 percent of monazite with accessory epidote, staurolite, hornblende, kyanite, tourmaline, garnet, and magnetite. Capers Island in Charleston County contains natural concentrations of heavy minerals whose tenor and components were described as being similar to the deposit on Bull Island (Neiheisel, 1958a, p. 3). The Capers Island placers are in the upper foreshore. They extend for a length of 2 miles, have an average width of 50 feet, and range in thickness from 1 to 2 feet. The oceanic side of the Isle of Palms, Charleston County, is lined with dunes and beach ridges parallel to the shore (Neiheisel, 1958a, p. 4—5; 1958b, p. 46—49). About 1,000 acres on the northern part of the island is covered by dunes which were estimated by Neiheisel to contain 850,000 short tons of heavy minerals in dune sands averaging 8 percent of heavy minerals. The largest concentrations of heavy minerals are in the lower dunes. Monazite makes up less than 1 percent of the concentrate from dune sand (table 84). A heavy—mineral deposit occurs 0.5 mile south of the northernmost end of the island and extends 1 mile southward along the beach. It is wedge shaped and tapers southward having an average width of 30 feet and a thickness of 3~6 inches. According to Neiheisel (1958a, p. 4—5), this placer is estimated to contain 15,000 short tons of heavy minerals of which 55 percent is ilmenite. A beach on the northern part of Edisto Island; Charleston County, was said to contain natural con— centrations of heavy minerals in the upper foreshore area for a length of 3 miles (Neiheisel, 1958a, p. 5). The placer is 10—40 feet wide and 2 inches to 2 feet TABLE 84.—Abundance of heavy minerals, in percent, related to average height of sand dunes on the Isle of Palms, Charleston County, 8.0. [Modified from Neiheisel (1958, p. 46—51)] 7-ft 12ft 35—ft dunes dunes dunes Ilmenite ______________________ 40 35 31 Epidote ______________________ 32 30 22 Hornblende ___________________ 4 9 20 Zircon _______________________ 8 6 6 Staurolite ____________________ 4 6 5 Rutile ________________________ 3 4 3 Leucoxene ____________________ 4 5 4 Kyanite _______________ _ _ _ 2 2 4 Garnet _______________________ 1 1 1 Tourmaline ___________________ 1 1 1 Monazite, sillimanite, mag- netite, hypersthene __________ 1 1 2 261 thick. It consists of 65 percent of ilmenite, 3 percent of rutile, 6 percent of leucoxene, 12 percent of zircon, and 0.5 percent of monazite. Epidote and hornblende are not as common as they are on the islands to the north. Natural concentrates have formed on a 2-mile-long sector of the beach on Fripp Island, Beaufort County, from a point 0.5 mile south of the north end of the island (Neiheisel, 1958a, p. 6). The placer has an average width of 100 feet and ranges in thickness from 6 inches at its north end to 1 inch at the south. Mineralogical composition resembles the concentrates on Edisto Island. Along the southernmost mile of beach on Dewees Island, Charleston County, heavy minerals have been naturally concentrated into shorter, thinner, and nar- rower deposits than the placers on Bull Island or Capers Island, but the mineralogical composition is similar (Neiheisel, 1958a, p. 4). Hilton Head Island in Beaufort County was ex- plored for heavy minerals in 1954 and 1955 by the National Lead Co. and the US. Bureau of Mines (Johnson, H. S., 1960, p. 2). The results of this exploration were compiled by McCauley (1960, p. 1— 31), who presented a map showing the locations of the drill holes and detailed tables giving the mineralogical composition of the sands. The report is unique in its completeness compared to other published accounts of heavy minerals in the coastal sands of the Southern States. According to Mrs. McCauley‘s report the National Lead Co. drilled 545 holes and the Bureau drilled 265. To a depth of 10 feet the sand averaged 2.14 percent of heavy minerals where drilled by Na- tional Lead, and 20 percent of the holes were in sand that contained 3 percent or more of heavy minerals. In the area drilled by the US. Bureau of Mines the sand to a depth of 11.1 feet averaged 2.19 percent of heavy minerals, and 17 percent of the holes were in sand that had 3 percent or more of heavy minerals. Major heavy minerals in concentrates examined by the Bureau were 35.0 percent of ilmenite, 11.7 percent of zircon, 5.5 percent of rutile, and 1.43 percent of mona- zite. Apparently the best placers are along the north half of the beach and adjacent foredune areas where the sand averages 7.87 percent of heavy minerals. Estimates show at least 8 million short tons of heavy minerals in the drilled areas, which comprise about ‘ 18,000 acres. Small concentrations of heavy minerals are known on Sullivans Island in Charleston County and Hunting Island and Pritchard Island in Beaufort County (Neiheisel, 1958a, p. 6). Monazite is practically absent at Sullivans Island. 262 The heavy fraction of sand from Folly Beach, Charleston County, was reported by Martens (1935, p. 1566, 1585) to contain a little monazite: Percent Percent Ilmenite _____________ 55 Tourmaline ___________ 1 Zircon _______________ 14 Garnet _______________ 1 Rutile _______________ 4 Collophane ___________ 1 Monazite _____________ 2 Leucoxene ____________ 2 Epidote ______________ 1 0 Sphene _______________ Trace Staurolite ____________ 4 Zoisite _______________ Trace Sillimanite ___________ 1 Hypersthcne .......... Trace Kyanite ______________ 1 Corundum ___________ Trace Hornblcnde ___________ 2 An airborne radioactivity survey of the Atlantic Ocean beach between the mouth of the South Edisto River, 8.0., and Cape Fear, N.C., disclosed abnormal radioactivity at six localities in South Carolina (hieuSchke and others, 1953). No ground checks of the sources of the radioactivity were made, but it was assumed that the radioactive sources are minerals that occur in black sands found locally on this part of the coast. Probably monazite is the main radioactive mineral, but it was not specifically mentioned. The six anomalously radioactive areas, all in Charleston County, are the area immediately northeast of the mouth of the North Edisto River; Folly Beach; Isle of Palms; Bull Island; west of Cape Romain; coast southwest of the mouth of the Santee River. The beach and dunes on Wadmalaw Island in Charleston County produced about 30 aeroradioactivity highs which have been interpreted as probably resulting from surficial concentrations of monazite (Meuschke, 1955). The observations on the distribution of monazite, or of anomalously radioactive areas along the Atlantic beaches of South Carolina seem to indicate that mona— zite is more common on the part of the coast southwest of the mouth of the Santee River than it is to the northeast of that outlet. This stream, and its ancestral courses, may be the greatest single source of detrital monazite on the Atlantic seaboard. The large resources of monazite on Hilton Head Island, as proved by extensive drilling, are probably only a very small part of those in the coastal islands south of the outlet of the Santee River. SOUTH DAKOTA Minor accessory monazite occurs in lithium- and tin— bearing pegmatites in the Harney Peak uplift in the southern Black Hills and in the Nigger Hill uplift in the northern Black Hills of South Dakota (O’Harra, 1902, p. 67; Hess, 1909, p. 149; Ziegler, 1914a, p. 268; Connolly, 1925, p. 23; Connolly and O’Harra, 1929, p. 231; Rothrock, 1944, p. 58). rences are in the southern Black Hills pegmatite dis— The reported occur- * THE GEOLOGIC OCCURRENCE OF MONAZITE trict, Pennington and Custer Counties, and the Tinton district, Lawrence County, in the Nigger Hill uplift. Very little specific discussion of the geologic relations of the monazite in the crystalline rocks has yet been given, and this fact reflects the scarcity of the mineral in these localities (Page and others, 1953). Small amounts of monazite were said to have been found in the gold and tin placers in the Harney Peak and Nigger Hill uplifts. The cycles of placer forma- tion in the Black Hills were said by Connolly (1933, p. 6—9) to have begun with the formation of gold placers in Cambrian time during a period of weather- ing and erosion following the deposition of lode deposits in Precambrian time. As a result of later erosion, only small remnants of the Cambrian placers are left. Late Tertiary or early Quaternary erosion stripped Paleozoic and Mesozoic sedimentary rocks from the Black Hills dome and formed placer deposits now seen as high benches. Increasingly younger placers formed on low benches and in the present channels of the streams. Accompanying the gold in the placers are small amounts of monazite, cassiterite, columbite-tantalite, wolframite, scheelite, beryl, garnet, magnetite, hematite, ilmenite, tourmaline, and barite. Monazite has not been saved during the mining of the gold and tin. In the Harney Peak area, small amounts of detrital monazite have been reported from placers along Spring Creek and its tributaries in Pennington County (Ziegler, 1914b, p. 192). A concentrate from a cassiterite placer near Tinton, Lawrence County, was said by Day and Richards (1906b, p. 1214—1215) to have the following mineralogical composition: Pounds per Pounds per short to'n short ton Magnetite ____________ 504 Cassiterite ____________ 66 Ilmenite _____________ 128 Dolomite _____________ 20 Garnet _______________ 82 Other minerals ________ 80 Hematite _____________ 804 Gold _____________ Present Monazite _____________ 6 Zircon _______________ 20 Total __________ 1, 998 Quartz _______________ 288 The degree of concentration was unspecified. Seem- ingly monazite is much less common in the tin placers in South Dakota than in other tin deposits. There are no analyses to show the amount of thorium oxide in the South Dakota monazite. TENNESSEE Accessory monazite occurs in a boulder of gray coarse-grained granite in a boulder bed in the northern arenite sequence of the Ocoee Series exposed 3—4 miles west of Tuckaleechee in Blount County, Tenn. (Car- roll and others, 1957, p. 185) . SOUTH DAKOTA, TENNESSEE, AND TEXAS Monazite-bearing fossil placers were reported by R. A. Laurence (written commun., 1951; oral commun., 1960) at several places in Tennessee. They occur in the Precambrian Ocoee Series in the southeastern part of Tennessee near the border with North Carolina; in the basal sand of the Devonian Chattanooga shale, but specific localities have not been cited; and in a Paleo- cene sinkhole at Indian Mound, Stewart County. In 1957 some prospecting was done in Benton, Carroll, and Henderson Counties for rare-earth-bearing heavy minerals associated with detrital ilmenite in probable marine deposits in the Cretaceous McNary Sand (Eng. and Mining J our., 1957; Gillson, 1958, p. 103) . Terrace deposits along the Cumberland River in Stewart County were reported to be monazite bearing (R. A. Laurence, written commun., 1951). Alluvial deposits in the valley of the French Broad River and some of its tributaries in Sevier and Cooke Counties were said by R. A. Laurence (oral commun., 1960) to contain monazite. Three samples of Recent sand from the bed of the Mississippi River at Memphis, Shelby County, were examined by Russell (1937, p. 1316—1325) and found to have small amounts of monazite. TEXAS Rare-earth minerals were discovered in a large body of pegmatite at Baringer Hill, Llano County, in 1887, and they were intermittently quarried until 1907, prin- cipally by W. E. Hidden who was an important figure in the Carolina monazite industry (Hess, 1908; Landes, 1932; Sellards and Evans, 1943, p. 376). The locality, now flooded by Lake Buchanan, was worked for its yttria minerals, of which many varieties were found, but detailed lists of the minerals found at Baringer Hill do not include monazite. Monazite was also unreported from other crystalline rocks of Texas. The heavy minerals in 31 samples of sedimentary rocks of Eocene, Oligocene, and Miocene age in Fayette County were studied by Bowling and Wendler (1933, p. 536—540). Monazite was found to be a scarce accessory mineral in 7 of the 31 samples and was questionably identified in another sample. The miner- alogical composition of the eight monazite-bearing samples, which come from the vicinity of La Grange, Flatonia, and Ledbetter, is shown in table 85. Most of the material studied was sand, but reworked silicic tufl's and bentonite are a large part of the Catahoula section, and the basal Oakville, which unconformably overlies the Catahoula, commonly contains volcanic ash mixed with well-rounded quartz grains and coquina debris. Apparently these sediments were deposited under fluvial, lagoonal, and littoral condi- tions. Nothing in the descriptions relates the monazite 263 TABLE 85.—Mineralogical composition of 'monazite-bearing con- centrates from sand of Tertiary age exposed m Fayette County, Tex. [Modified from anyalyses by Wendler (in Bowling and Wendler, 1933,p. 540). Symbols used: A, 20—80 percent; 0, 10—20 percent; R, 1—10 percent, P?, possibly present; Ab, absent] Basal Catahoula Upper Oakville Jackson 1 2 3 4 5 6 7 8 Magnetite ............. - A A A A A A A A Limonite ______________ A C A A Ab A C A Zircon ... C A A C C A A A Ilmenite.. C 0 Ab C A C C C Pyrite-..- C Ab Ab Ab 0 Ab Ab Ab Leucoxene C 0 Ab C C C C C Kyanite-- C 0 Ab R Ab C C C Tourmaline . R R Ab Ab Ab R C R Rutile.... R Ab R R R R R R Epidote.- Ab C R R Ah 0 Ab P? Staurolite R Ab Ab R R R R R Monazite. R R R R R R P? R Biotite ...... R Ab R 0 Ab C R R Muscornte Ab Ab Ab Ab Ab C Ab Ab Garnet... R Ab Ab R Ab Ab Ab Ab Anatase Ab Ab Ab Ab R R Ab Ab Sphene--- Ab Ab Ab Ab Ab R Ab Ab Brookite ...................... Ab Ab Ab Ab Ab P? Ab Ab 1. 7 miles north-northeast of La Grange. 2. 1 mile south of Flatonia. 3. 10 miles southeast of Ledbetter on Cummins Creek. 4—5. Locality not given on authors‘ index map, p. 546. 6. 4 miles southwest of La Grange. 7-8. 4 miles south of Ledbetter. to the volcanic debris. Probably the monazite was derived from the reworking of older sedimentary rocks in which it occurs as detrital grains. The heavy minerals in Recent river and beach sands of Texas were studied by Bullard (1942, p. 1022) . He found that the Rio Grande, Nueces, and Trinity Rivers lacked monazite. Monazite-bearing concentrates, how- ever, were obtained from sand of the San Antonio River near McFaddin, Refugio County; Colorado River 3 miles south of Matagorda, Matagorda County; Brazos River at the mouth of the old channel southeast of Freeport, Brazoria County; and Neches River southwest of Lufkin, Angelina County (table 86). Concentrates from the Colorado River contain green hornblende in some abundance, but this mineral and the pyroxenes, typical of the sediment in the Rio Grande, are lacking in the other streams. Stable TABLE 86.——-M1Ineralogical composition, in percent, of monazite- bearmg concentrates from rwer sand m southeastern Texas [Modified from Bullard (1942, p. 1026, table 1). Symbol used: --, absent] San Colorado Neches Antonio River Brazos River River River 1 1 l 1 2 __________ 54 45 46 64 45 50 2 5 1 1 l 1 2 4 14 7 12 1 1 20 l ...................... Iron oxides. . . 4 l 2 1 2 10 Kyanite ______ 2 ............ 2 ...... 2 2 Leucoxene. 16 7 12 6 12 9 Monazite 2 1 1 2 l 3 Rutlle... 2 .................. 2 2 3 Stauroht 3 l 5 1 2 6 Tourmaline... 5 1 2 1 2 l ircon ................. 10 14 13 14 14 11 Enstatite ............................... 1 1 Hypersthene ..... . . . ...... 1 .......... Brookite.... ...... 1 1 264 resistate minerals are characteristic of the suites reported from the San Antonio, Brazos, and Neches Rivers. Heavy minerals were found by Bullard (1942, p. 1029—1034) to be very abundant in the beach sands of the Texas coast. Crude banding of the sands is very common. The dark layers show the concentration of heavy minerals on the beach by the surf and in dunes by the wind. Northeastward from the mouth of the Rio Grande along the beach of Padre Island the heavy sands give way rather abruptly from suites characteristically rich in basaltic hornblende and other minerals common to fluvial concentrates from the Rio Grande, to those typical of the Colorado, with the addition of monazite in many samples (table 87). Near the mouth of the Nueces River there is an in- crease in the relative abundance of the resistate minerals. Similar increases in the relative abundance of the resistate minerals occur near the mouths of the San Antonio and Brazos Rivers. Apparently the dis— tribution of the heavy minerals is influenced by a southward-flowing longshore current. Monazite in the beach sands is greenish-yellow to yellow round or irregular ellipsoidal grains. It is more common in the southern beach sands than in sand on Galveston Island (Bullard, 1942, p. 1034). UTAH Monazite-bearing titaniferous sandstone layers of Late Cretaceous age have been observed at three areas in Utah (Dow and Batty, 1961, p. 1—3). These sand- stone layers are fossil placer similar to those known in Arizona, Colorado, Montana, New Mexico, and Wyoming. Seven areas of titaniferous sandstone are known southeast of Emery, Emery County; 1 deposit THE GEOLOGIC OCCURRENCE OF MONAZITE is 011 the southwest flank of the Henry Mountains in Garfield County; and 14 deposits are on the Kaiparo- wits Plateau in Garfield and Kane Counties south of Escalante. Sixteen of the deposits were reported to contain an estimated 1 million short tons of titaniferous sandstone having an average grade of 0.09 percent of eThO2 (Dow and Batty, 1961, p. 1). The seven areas of titaniferous sandstone near Emery crop out along tributaries to the Muddy River about 6 miles southeast of Emery where the streams breach the Coal Cliffs (Dow and Batty, 1961, p. 14). Five outcrops are probably part of the same fossil placer, and the other two are parts of parallel but separate lenses of titaniferous sandstone. The sand- stone consists of quartz, feldspar, titanium minerals, zircon, magnetite, and monazite cemented by hematite and carbonates. The fossil placers occur near the base of the Ferron Sandstone Member of the Mancos Formation. They have an average thickness of 5 feet and contain 0.1 percent of eThOZ. The fossil placer on the southwest flank of the Henry Mountains is on the southwest side of Mount Hillars 57 miles by road south of Hanksville (Dow and Batty, 1961, p. 14—16). It occupies a channel near the top of the Ferron Sandstone Member, but in com— position it resembles the cemented black sand near Emery. In exposed size the fossil placer is 1,560 feet long, as much as 100 feet wide, and averages 3 feet in thickness. Samples from the deposit contained an average of 0.21 percent of eThO2. In the Kaiparowits Plateau area, 1 fossil placer is at the north end of the plateau 6 miles south of Escalante in Garfield County, and 13 are at the south- ern part of the Kaiparowits Plateau in Kane County. TABLE 87.—M1Zneralogical composition, in percent, of monazite—beartng concentrates from beach sands on the gulf coast of Texas [Modified from Ballard (1942, p. 1028, table 2)] l 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 A atite ___________ 1 1 ____ ___. ___, 2 1 l __._ .-_. .._. .._. 1 l __._ .._. l 1 __._ l .._. Aiigite ____________ 12 17 9 5 8 5 4 7 1 1 2 2 1 1 2 l 2 Basaltic hornblend 6 8 10 4 9 10 9 12 8 1 1 1 1 1 2 1 l 1 Enstatite.. 1 .._. .._. 1 1 ..,. .._. 1 1 .... .._. 1 .._. .._. 1 1 2 1 1 Epidote __. 6 6 7 6 6 6 8 5 4 5 3 3 4 9 7 7 5 5 G arnet ................................ 5 3 7 6 5 2 5 3 1 1 . . . . 2 5 7 8 5 6 4 7 Hornblende ........................... 8 15 8 6 16 21 15 27 24 9 15 24 24 4 8 .. .. 9 ..2 22 16 15 17 Hypersthene ................................ 2 2 2 1 2 2 1 ..._ 1 1 .._. .._. 1 1 .._. .._. __._ __._ .._. 1 1 .._. .._. Kyanite........ ____________ 1 1 3 1 ____ 2 1 1 __._ 2 .._. 2 1 __._ .._. .._. 1 2 1 ._._ ____ Leucoxene- 4 8 8 4 7 12 5 9 3 9 12 16 24 19 4 10 3 12 10 11 14 15 13 Limouite. 1 2 __._ 2 2 3 2 1 1 1 2 1 2 --_. 1 2 1 1 1 1 5 4 1 Monazite 3 2 3 3 1 I l l 1 1 1 1 1 1 1 1 2 2 2 3 1 3 1 Opaque black mlnerals 41 31 34 53 40 29 40 23 28 46 54 35 17 23 45 45 58 36 28 26 27 35 33 Rutile ..................... 1 -___ 1 ____ _-__ .._. 1 1 .-_. 1 1 2 3 1 1 --.. l 1 3 .._. 2 1 --_- Staurolite.. . 2 1 1 2 1 1 1 1 3 3 4 3 5 1 1 1 1 2 3 3 1 2 2 Tourmaline __._ 2 1 4 1 1 2 3 5 6 11 5 11 7 5 1 5 1 3 5 8 4 5 4 Zircon ........................................................... 4 2 3 5 l 2 3 2 3 9 8 8 2 9 32 16 26 15 3 7 11 5 6 1. Brazos Santiago, Cameron County. 14. St. Joseph Island, Aransas County. 2. South end of Padre Island, Cameron County. 15—16. Matagorda Peninsula, Matagorda. County. 3-4. Padre Island, Cameron County. 17. Coast south of mouth of Brazos River, Brazorla County. 5-6. Padre Island, Willacy County. 18. South end of Galveston Island, Galveston County. 7—9. Padre Island, Kenedy County. 19. Galveston Island, Galveston County. 10. Padre Island, Kleberg County. 20. North end of Galveston Island, Galveston County. . North end of Padre Island, Nueces County. 21—22. Patton Peninsula, Chambers County . South end of Mustang Island, Nueces County. . North end of Mustang Island, Nueces County. 23. Coast west of Sabine Pass, J efierson County; includes 6 percent pyrite. UTAH AND The placer south of Escalante has an exposed length of 600 feet, width of 200 feet, and thickness of as much as 12 feet. It occupies a channel in massive white sandstone in the Straight Cliffs Sandstone (Dow and Batty, 1961, p. 11). A seam of coal is exposed about 60 feet below the fossil placer. In its upper half the placer is dark purple, very hard, and contains 0.09 percent of eThOz. The lower half of the placer is dark bufl', stratified, and averages 0.15 per- cent of eThOz. The placers in the southern part of the Kaiparo‘wits Plateau include three in Rees Canyon, eight in Croten Canyon, and two in Sunday Canyon, Kane County (Dow and Batty, 1961, p. 11—14). The Rees Canyon deposits are reddish-brown soft sandstone having 0.06— 0.09 percent of eThOz. In Croten Canyon the fossil placers are exposed on the walls as much as 300 feet above the floor of the canyon, and only one is acces- sible from the floor. Outcrop lengths of the deposits are 200—580 feet, widths are 200—250 feet, and thick- nesses are 4—5 feet. The two placers in Sunday Canyon cap benches on the canyon wall and are inac— cessible from the floor. They are about 4 feet thick, 200—300 feet long, and 200 feet wide. A composite of three samples from accessible deposits in Croten Canyon contained 0.08 percent of eThOz. Recent auriferous placers at Hite in Garfield County and the Jensen district of Uinta County were reported by Day and Richards (1906b, p. 1216—1217) to contain small quantities of monazite. Concentrates from these localities have from a trace to 25.4 pounds of monazite per short ton: Composition of concentrate (lb per short ton) Hite Jensen district Magnetite ____________________ 800 848 1, 532 Chromite _______ -___ ________ 677 321 Ilmenite ________ - 32 __________________ Garnet _______________________ 24 300 78 Hematite _____________________ 1, 032 __________________ Monazite _____________________ Trace 25. 4 2 Zircon _______________________ 72 1 20 43 Quartz _______________________ 24 22 16 Unclassified minerals __________ 16 __________________ Total ___________________ 2, 000 1, 992. 4 1, 992 The concentrates from the Jensen district were reported to have come from gravel that contained 3 pounds of black sand per cubic yard. The original source of the monazite in this area is not known. In the Hite area, however, the monazite was probably reworked from fossil placers of Late Cretaceous age, an inference that is supported by the abundance of 265 VE RMONT hematite in the concentrate. Hematite is a cement in the fossil placers. VERMONT Monazite-bearing Bethlehem gneiss of the Bellows Falls pluton is exposed in Vermont in the bend of the Connecticut River immediately south of the town of Bellows Falls, Windham County (Kruger, 1946, map). At Ascutney Mountain, Windsor County, a complex stock of hornblende-biotite—nordmarkite, alkalic gran- ite, and monzonite is intruded along a contact between carbonaceous quartz—sericite phyllite on the east and muscovite-biotite-epidote gneiss on the west (Daly, 1903, p. 14—36). The phyllite is greatly crushed and crumpled near the stock and displays a contact meta- morphic aureole about 500 feet wide. The aureole consists of hornfels containing cordierite, sillimanite, corundum, and intensely pleochroic metamorphic biotite that has abundant pleochroic halos. A very large variety of alkalic rocks are present in the main stock, a subsidiary mafic stock, and dikes. Only one variety of rock is monazite bearing. This is horn- blene—biotite-nordmarkite, which is the earliest of the four chief phases of the main stock. Monazite is an abundant accessory mineral, although it constitutes less than 1 percent of the rock, at exposures in the Windsor quarry on the flank of Ascutney Mountain (Daly, 1903, p. 56; Jacobs, 1934, p. 9). The mona- zite was said by Daly to occur as nearly colorless gray grains having a yellow tint. All observed grains lack crystal form. They are rounded to subrounded and reach a maximum diameter of 0.04 inch. Very small needles of apatite and square sections of mag- netite are present in the monazite. Primary allanite, intergrown in many places with hornblende, forms mantles about some of the grains of monazite. The association of allanite with monazite in the earliest phase of the stock and the absence of mona- zite from later rocks suggests that a reaction between the monazite and the magma was taking place as the nordmarkite was emplaced. Continued reaction ap- parently led to elimination of monazite in later phases of the intrusive at Ascutney Mountain. Whether the absence of crystal form in the monazite grains was due to rounding resulting from reaction with the magma, or to low power of crystallization of the monazite is not known. The alteration of monazite to allanite has been ob- served in some pegmatites in the United States and has been related to reactions associated with declin- ing pressure and temperature. Possibly at Ascutney Mountain the monazite formed early in the magma chamber and as conditions of pressure and temperature 266 dropped during the intrusion of the different phases of the stock, reactions took place between the mona- zite and the magma resulting in the disappearance of monazite as a mineral phase. Allanite and other minerals proxy for the monazite at lower pressure and temperature. VIRGINIA CRYSTALLIN E R0 0K5 The first published reports of monazite in Virginia were a group of analyses made by Dunnington and Kéinig in 1882 on massive monazite from a mica mine in pegmatite near Amelia Court House, Amelia County (Dunnington, 1882a, p. 154; 1882b; Kéinig, 1882a; 1882b). Thereafter, monazite from the Amelia area was mentioned in 21 of the 29 other reports which reported occurrences in the State, although the Amelia mica mines are of no importance as a commercial source for monazite. The first systematic account of the distribution and occurrence of monazite in the State was prepared in 1953 by Mertie (1953, p. 15—16, pl. 1) as the result of his studies of the resistate heavy accessory minerals in the weathered rocks of the Southeastern States. Mertie observed that monazite occurs in some bodies of granite and granite gneiss exposed in a belt that extends southward from the vicinity of Five Mile in Spotsylvania County a few miles west of Fredericks- burg to the James River in Goochland County at a point west of Richmond. At the James River the belt of monazite-bearing plutonic rocks was found by Mertie to split into two segments: an eastern seg~ ment that extends generally southward to the State line near Bracey (Sears, 1955) in Mecklenburg County and a western segment that extends southwestward from the James River to the State line near Stuart in Patrick County. As of 1953 Mertie described 27 localities where monazite-bearing rocks are present in these belts, and these occurrences have since been cited as the principal known localities in the State (Dietrich, 1958, p. 53). In the area from Five Mile south to the James River, monazite was found by Mertie (1953, p. 16) to be present in six samples of granite gneiss and one of granite. These include two samples of granite gneiss from the vicinity of Five Mile and one from Post Oak in Spotsylvania County, a specimen of granite gneiss from the basin of the Little River and a sample of granite from the Chickahominy River area in Hanover County, and two samples of granite gneiss from exposures near the James River west of Richmond in Goochland County. THE GEOLOGIC OCCURRENCE OF MONAZITE In the area between the James River and the State line at Bracey in Mecklenburg County, monazite was found by Mertie (1953, p. 16) in granite exposed 7.4 miles southeast of Amelia Court House, Amelia County, and in gneissic granite from localities near Wilson in Dinwiddie County, Blackstone in Nottoway County, and South Hill in Mecklenburg County. Granite in Chesterfield County is monazite bearing. An analysis of the total rare-earth and thorium oxide precipitate from monazite from the granite in Chesterfield County was published; the precipitate was said to have con- stituted 61.3 percent of the monazite (H. J. Rose, Jr., oral commun., 1960). Recalculation of the published analysis shows the following chemical composition: [Analysts: Murata and Rose (in Murata and others, 1957, p. 148)] Percent La203 _____________________________________ 12. 5 0802 ______________________________________ 25. 9 PI'eOu _____________________________________ 2. 6 Nd203 _____________________________________ 9. 1 8111203 _____________________________________ 1. 8 Gd203 _____________________________________ . 9 Y203_ _ _ _; _________________________________ l. 7 Th02 ______________________________________ 6. 8 Total ________________________________ 61. 3 Monazite was found by Mertie (1953, p. 15—16) at 16 localities between the James River and the State line near Stuart, Patrick County. It occurs in granite gneiss near Macon and south of Tobaccoville within 0.4 mile of the Appomattox River in Powhatan County, in gneiss in Cumberland County near the Appomattox River north of Farmville, and in granite and granite gneiss exposed at three localities west of Farmville, Prince Edward County. Monazite-bearing granite was found in the vicinity of Madisonville and Red House, Charlotte County, in granite gneiss ex- posed near Renan, Pittsylvania County, in granite gneiss and aplitic granite about 0.5 mile southwest of Mountain Valley, Henry County, and in three occur~ rences of granite and two of granite gneiss around Stuart, Patrick County. In this same zone, mona- zite was found in magnetite-rich layers of mica schist east of Chestnut Knob, Henry County, by Stow (1955b, p. 2). Mica mines in pegmatite dikes in the area around Amelia Court House, Amelia County, have been the source of museum specimens of massive monazite, but the mineral is not present in commercial quantities although individual masses that weigh from 8 to 20 pounds have been found (Dunnington, 1882b; Hotch- kiss, 1884—85, p. 169; Watson, 1909, p. 131; 1917, p. 475—477 ; Sterrett, 1913, p. 1048; Jones, W. H., 1949b, p. 582). The area in which the dikes occur is under- VIRGINIA lain by a sequence of gneissic and schistose rocks cut by granitoid and gabbroic rocks (Lemke and others, 1952, p. 105—108; Pegau, 1929, p. 542—545; 1932, p. 36, 54, 61; Hickman, 1950). According to Lemke and associates, quartz-biotite schist, biotite augen gneiss, thinly foliated biotite schist and gneiss, garnetiferous mica schist and gneiss, and hornblende schist and gneiss of poorly understood age and relations are the main varieties of metamorphic rocks in the Amelia area. Garnetiferous gneiss rich in pegmatite and con- taining abundant graphite and sparse sillimanite is exposed at several places, but for the most part the metamorphic rocks seem to be at the kyanite—staurolite subfaices. Fine- to medium—grained foliated locally porphyritic biotite-quartz monzonite is the most com- mon granitic rock in the area. Diorite is present in the western and southwestern part of the district. Pods, thin conformable stringers, and irregular masses of pegmatite occur in the quartz monzonite and dio— rite, and dikes of pegmatite, as much as several hun- dred feet wide and half a mile long, occur in the schists and gneiss. The mica pegmatites of the Amelia area are dis- tinctly discordant and strike about eastward, nearly normal to the trend of the pegmatite-bearing zones in the schist (Lemke and others, 1952, p. 106—108). Con- tacts are remarkably straight and regular. Most of the dikes are distinctly zoned with cores of massive quartz. The pegmatite dikes consist mainly of plagio- clase, quartz, and perthite, with lesser amounts of muscovite and biotite. Accessory minerals are com— monly garnet, beryl, black tourmaline, and apatite; very scarcely they are cassiterite, tantalite, allanite, sulfides, monazite, and other minerals. The scarce constituents were said by Lemke and associates to have formed late through deuteric or hydrothermal altera- tion. Late alteration led to mineralogically complex pegmatites such as those exposed at the Rutherford (Fontaine, 1883, p. 331; Pegau, 1928) and More- field (Glass, 1935, p. 744) mines. These complex pegmatite dikes are extensively albitized and contain muscovite, zinnwaldite, tantalite, columbite, microlite, beryl, phenacite, topaz, monazite, cassiterite, apatite, sericite, and sulfide minerals. The complex Morefield and Rutherford pegmatite dikes were described by Lemke, J ahns, and Griffitts (1952, p. 130) as having formed in two stages. In the first stage each dike crystallized inward from its walls with early crystallization of plagioclase and the formation of a border zone, a medium- to coarse— grained granitoid wall zone, an intermediate zone rich in graphic granite, an intermediate zone rich in blocky perthite, and a discontinuous quartz core. In the 267 second stage of the pegmatites, solutions penetrated the dikes causing widespread replacement of quartz, perthite, and probably wall-zone plagioclase by sodic albite. Muscovite, zinnwaldite, and many less common minerals, including monazite, were thought to have formed then, but the details are imperfectly known. Monazite occurs in pegmatite exposed by the Cham- pion and Rutherford mines north of Amelia Court House and the Morefield mine east—northeast of Amelia. The first reports of monazite in the Amelia area referred to material found in the Rutherford mine in 1882. The monazite was said by Fontaine (1883 p. 337) to occur usually as large masses, never as single or small crystalls, but small single crystals were subsequently observed (Lemke and others, 1952, p. 130). As reported by Fontaine the masses of monazite are aggregates of distorted crystals which often show well-formed faces on individual particles. The masses are yellowish brown and dark grayish brown; a few are orange. Included in the dark- garyish-brown monazite are flakes of white mica. Commonly the different colors are associated in the same specimen. Where weathered, the monazite is gray and has an earthy luster. The later reports of Glass (1934, p. 754, 763) and Lemke, Jahns, and Griffiths (1952, p. 130) described reddish-amber to olive-brown monazite and stated that it occurs sparsely in albite as individual tabular skeletal crystals enclos- ing crystals of manganotantalite. It was said to closely resemble microlite. Early analyses of monazite from the pegmatites at Amelia Court House are given in table 88. Dunning- ton’s analysis showed 18.6 percent of T1102, and the analyses by Penfield disclosed 14.07 and 14.39 percent TABLE 88.— Chemical analyses of monazite, in percent, from peg- matites at Amelia Court House, Va. [Analystsz Dunnington (1882a), Konig (1882b), Penfleld (1882 p. 252), and R. Jo Strutt (in Hess, 1913, p. 1009) and H. J. H. Fenton in 1905. Symbol used: -_, not determined] 2 3 4 5 E6283 _____________ 13. g 29. 89 _ _ _ _ a2 3 _____________ 1 . .. - _ _. DigOa _____________ 24. 4 26‘ 66 i _ - _ _ Y203 ______________ 1. 1 73. 82 __ __ -_ Er203 (group) ______ - _ _ _ - - _ _ ThOz ______________ 18. 6 14. 23 14. 39 2. 43 U303 ______________ _ _ _ _ - _ . 1 P205 ______________ 24. 04 26. O5 26. 12 _ - _ _ 8102 ______________ 2. 7 _ _ 2. 85 _ _ _ _ €463 —————————————— - g4 - _ — — _ _ - - e 3 _____________ . _ - _ _ _ _ ab ______________ _ _ } 1- 00 i _ _ _ _ _ _ MgO ______________ _ _ - _ _ - _ _ _ _ Loss on ignition- _ - _ - _ . 45 . 67 _ _ _ _ Total _______ 98. 38 101. 32 100. 42 _ - _ _ Specific gravity _____ - - 5. 1—5. 4 5. 30 _ _ _ _ 268 of Th02, but the analysis by Strutt indicated only 2.4 percent of ThOz. The early analyses indicating high thorium oxide have subsequently been widely quoted (Watson, 1907, p. 303; 1916, p. 940; Glass, 1934, p. 234—235), but later analyses have disclosed somewhat less thorium oxide. Microchemical analyses of the monazite by Edith Kroupa showed the following amounts (Lane, 1934, p. 28): Percent A B RE203 __________________________________ 48. 98 _______ Th02 ___________________________________ 7. 21 7. 89 U303 ___________________________________ . 2 _______ SiOz ____________________________________ 2. 88 _______ A1203 ___________________________________ 3. 43 _______ F6203 ___________________________________ 1. 90 _______ CaO ____________________________________ . 87 _______ MgO ___________________________________ . 23 _______ PbO ____________________________________ 1. 33 . 93 The results of a spectrochemical analysis of the total rare—earth and thorium oxide precipitate from mona— zite from pegmatite at Amelia Court House has been published (Murata and others, 1953, p. 294). Accord- ing to H. J. Rose, Jr. (oral commun., 1960) the pre— cipitate was 71.02 percent of the monazite, and the published analysis when recalculated to sum 71.02 percent shows that the monazite from Amelia contains the following percentages: Percent 118.203 _____________________________________ 11. 40 C802 ______________________________________ 26. 44 P125011 _____________________________________ 3.15 Nd203 _____________________________________ 12. 90 szog _____________________________________ 3. 51 Gd203 _____________________________________ 1. 15 Y203_ ______________________________________ 1. 36 Thog ______________________________________ 11. 11 Total ________________________________ 71. 02 The Amelia Court House monazite contains from 11 to 14 percent of Th02, and this composition makes it among the most thorium oxide—rich monazite reported from the United States. Yet, it comes from an environment that is by no means the most plutonic in which pegmatites are found in the country. Also, monazite is relatively uncommon in the muscovite- bearing pegmatites of the Piedmont. The regional geologic relations and significance of the high—thorium oxide monazite in the mica pegmatites of the Amelia district is not as yet understood, but it is intriguing that the occurrence is virtually at the contact of the two belts of monazite-bearing rocks defined by Mertie (1953, pl. 1). Monazite was said to occur in Lovingston Quartz Monzonite Gneiss exposed near the airport at Charlot- THE GEOLOGIC OCCURRENCE OF MONAZITE tesville, Albemarle County, and at a point about 8 miles west of Culpeper, Culpeper County (Stow, 1955b, p. 2). Outcrops of granodiorite gneiss 1.6 miles to the west of Sperryville contain accessory monazite which is unusually radioactive (Jafl'e and others, 1959, p. 114). FOSSIL PLACERS Fossil placers of Precambrian(?) and Cambrian age have been observed in Virginia, but there is scant information about them. Quartzite of Pre- cambrian(?) age associated with the Lovingston Quartz Monzonite Gneiss in Culpeper County was described by Mertie (1956, p. 1755) as being monazite bearing, and a detrital origin for the monazite was implied. A magnetite-rich layer 12—20 inches thick in Wissahickon Schist exposed 5.4 miles south—south- west of Martinsville, Henry County, was observed by Mertie (1955, p. 1692—1693) to consist of 69 percent of magnetite, 15 percent of ilmenite, 9 percent of monazite, 3 percent of zircon, 2 percent of corundum, and 2 percent of quartz and other minerals. The enclosing rocks are biotite-kyanite schist formed by the metamorphism of sedimentary rocks. The layer of heavy minerals was interpreted by Mertie to be a fossil placer. Detrital monazite was reported to be concentrated in sandstone of Early Cambrian age at several placers in the Blue Ridge in Virginia, but descriptions and locations of these fossil placers have not been published (Sears, 1955). STREAM AND BEACH DEPOSITS Monazite was found in 4 out of 19 concentrates panned from sand and gravel in tributaries to the Ararat River and Dan River in the southwestern part of Patrick County (A. M. White, written commun., 1954). A sample of fluvial gravel from a tributary to the Ararat River contained 0.2 pound of monazite per cubic yard. Three tributaries to the Dan River were the sources of gravel with small amounts of mon azite : Tenor of gravel (lb of monazite per cu yd) Big Creek __________________________________ 0. 2 Archies Creek ______________________________ . 06 Squirrel Creek ______________________________ . 3 The concentrates consisted mainly of magnetite, epi- dote, staurolite, small quantities of ilmenite, and a trace of garnet and zircon. The deposits are not com— mercial sources of monazite. A few grains of monazite were found in concentrates panned from gravel in Birch Creek, Pittsylvania County, and Sandy Creek, Halifax County (J. W. Whitlow, oral commun., 1953). WASHINGTON A petrographic study of Recent beach sand along the coast of Princess Anne County from Cape Henry southward to the State line was made by Alford, Kane, and Marthison (1956). Results of the study showed that the sands throughout this distance con- tain the same minerals but with a systematic south— ward variation in character of the grains. A southward decrease in the abundance of magnetite, ilmenite, and less stable minerals was noted. Also seen was a southward decrease in the average grain size and an increase in the degree of roundness of the grains. In the order of decreasing frequency of occurrence of the grains in the beach sands, the heavy suites consist of magnetite, ilmenite, leucoxene, zircon, garnet, epidote, staurolite, hornblende, kyanite, tourmaline, sillimanite, muscovite, monazite, hypersthene, brookite, topaz, diopside, olivine, biotite, and enstatite. The geologic source of the heavy minerals was not determined, but their main geographic source was thought by Alford, Kane, and Marthison to be the Chesapeake Bay, the sediments of which had previously been shown (J affe and Hughes, 1953) to be very slightly radioactive. Evidently monazite is much too scarce along the coast of Princess Anne County to form workable monazite placers. WASHINGTON Monazite was listed by Glover (1936, p. 8—9) in a tabulation of 52 nonmetallic minerals of no economic importance which occur in various rocks and veins exposed in Washington, but localities and modes of occurrence were not given. The apparent sparseness of monazite in the State was further indicated by its absence from the bibliography and indexes of mineral occurrences compiled by Bennett (1939, p. 91424). There are, however, a few reports that describe minor occurrences of monazite in crystalline rocks, lake sedi- ments, stream deposits, and the beaches of Washington. Monazite occurs in biotite-rich pegmatitic segrega— tions near the contacts of granite with gneiss and schist in the vicinity of Sherman Creek Pass, Columbia Mountain, and Sherman Park in Ferry County. These deposits were explored by pits and diamond-drill holes in the early 1950’s when hundreds of claims were staked in the area, but» as of 1956 the deposits had not been exploited (Huntting, 1956, p. 352). Residual and colluvial clay deposits derived from granitic and metamorphic rocks near Freeman, Spo— kane County, were reported by Goodspeed and Wey- mouth (1928) to contain accessory monazite. A clay pit near Freeman was found by J. W. Hosterman (oral commun., 1963) of the US. Geological Survey to expose weathered monazite—bearing granodiorite. He 269 also found weathered monazite-bearing garnetiferous sillimanite schist a short distance west of Saltese Flats, Spokane County. Analyses of two samples of monazite separated by Hosterman from concentrates panned from residuum and of a sample from sedimentary rock exposed in Spokane County are given in table 89. The results of these analyses show that monazite in this part of Spokane County contains about 3.6 percent of T1102. The amount of monazite in the granodiorite and silli— manite schist seems to be too low for monazite mining, and even if the monazite were concentrated in placers, the tenor in thorium oxide is too low for commercial exploitation unless special economic factors were to intervene. TABLE 89.—Thorium and uranium composition, in percent, of monazite from Spokane County, Wash. [Analystr J. J. Warr, Jr., U.S. Geol. Survey, in 1963] Lab. No. Source of monazite Location Th0: UaOa 160816.... Saprolite oi granodiorite... Cllay pit at Freemarié sec. 2. 74 0.65 , T. . . . 17..-. Saprolite of garnetiferous Drill hole on, point of hill 4. 06 .20 sillimanite schist. 0.95 mile west of Saltese Flats, sec. 32, T. 25 N., R. 44 E. 18.... Sedimentary rock, Latah Sommers clay pit, sec. 35, 3. 92 . 26 Formation. T. 25 N., R. 44 E. At a locality 4: miles northwest of Okanogan on Happy Hill, Okanogan County, 15 claims and some leased land were prospected in the early 1950’s, and ore containing as much as 5 percent of monazite was found (Huntting, 1956, p. 353). Geology of the occurrence was not discussed by Huntting. Kaolin deposits of lacustrine origin in the Freeman, Mica, and Chester areas of Spokane County were said by Goodspeed and Weymouth (1928, p. 687) to be associated with sandy layers containing minor detrital monazite. Sedimentary rocks in the Latah Formation of Ter- tiary age exposed at the Sommers clay pit near Spo- kane in Spokane County contain detrital monazite (J. W. Hosterman, oral commun., 1963). Because the detrital monazite is nearly identical to monazite from sillimanite schist west of the Saltese Flats in amount of thorium oxide and uranium oxide, it seems likely that the detrital monazite was locally derived from metamorphic rocks. Possibly the most favorable places in the area for fluviatile or lacustrine monazite placers would be where sedimentary rocks of the Latah Formation serve as an intermediate host for monazite. Stream sediments in at least six places in the State are known to contain detrital monazite, but the min- eral is of no economic importance at any of these 270 localities. Stream gravel at Marcus in Stevens County, the Wilmont Bar gold placer on the Colum- bia River in Ferry County, the Columbia River in Douglas County, the Snake River in Asotin County, and the Seattle gold placer in King County is mona- zite bearing (Day and Richards, 1906b, p. 1216—1219; Huntting, 1956, p. 184). Terraces 20 and 100 feet above the Columbia River at the Wilmont Bar placer contain monazite, magnetite, ilmenite, and zircon (Huntting, 1956, p. 184). For the most part the flu- vial sediments were reported to have only a trace of monazite, but concentrates from the Wilmont Bar contain 30 pounds of monazite per short ton (table 90). At Brush Prairie, Clark County, an auriferous concentrate probably of placer origin was said by Day and Richards (1906b, p. 1218—1219) to contain a trace of monazite. Gold placers :at Sherman Creek Pass, Ferry County, are monazite bearing. Beach deposits in, Clallam County, at Moclips in Grays Harbor County, and in Pacific County are sparsely monazite bearing. One sample of natural beach sand from Moclips was said by Day and Rich- ards (1906b, p. 1218) to contain 71.5 pounds of mona- zite per short ton of sand as found on the beach. No commercial sources for monazite have been found in these placers, and they are not likely to be present. WEST VIRGINIA Paleozoic sandstones in West Virginia were noted by Martens (1932, p. 72—73) to contain minor amounts of detrital monazite :along with more common detrital heavy minerals like zircon, rutile, ilmenite, magnetite, and mica. The monazite was found in sandstones ranging in age from Late Devonian to Pennsylvanian in about 60 samples from 12 oil and gas wells in the northern part of the State in Wetzel, Monongalia, Tyler, and Marion Counties. It occurs as small well- THE GEOLOGIC OCCURRENCE OF MONAZITE worn light-yellow grains. One or two grains of mon- azite were found in most of the heavy fractions in which it was seen. From this sparseness Martens (1939, p. 15) inferred that the monazite might also have been present in other sandstones where it was absent from the small concentrate that was studied. In any event the monazite seems only to be a miner- alogical curiosity in these rocks. Martens observed sparse monazite in all six concentrates collected from sandstone in the Chemung Formation of Devonian age near Rowlesburg, Preston County (Martens, 1939, p. 24). Other heavy minerals were leucoxene, musco- vite, chlorite, biotite, zircon, tourmaline, rutile, pyrite, apatite, anatase, brookite, xenotime, and ilmenite. Oriskany Sandstone of Devonian age in Kanawha County was found to have less than 0.01 percent total heavy minerals, exclusive of pyrite, of which monazite was a very minor component. Nine stratigraphic units intersected by the J. L. Jamison well 1, 2 miles southwest of Morgantown, Monongalia County, con- tained very scarce monazite among the accessory min- erals (table 91). Monazite may account for some of the radioactivity noted by McKeown (1954, p. 166) in exposures of the Mississippian Pocono Formation 1.3 miles south of Marlinton, Pocahontas County. WYOMING Although allanite and other rare-earth and tho- rium-bearing minerals have been reported by several writers to occur in iron-manganese veins, pegmatite, granite, altered monzonite and syenite porphyry, and gneiss in Wyoming, there seems to be no reported occurrence of monazite in crystalline rocks of the State (Osterwald and Osterwald, 1952, p. 166). The main known deposits of monazite are fossil placers in sandstone in the Deadwood Formation of Cambrian age and sandstones of Cretaceous age. The very few TABLE 90.—Mineralogical composition, in pounds per short ton, of monazite—bearing aurife'rous sands and concentrates from streams and beaches in Washington [Modified from analyses by Day and Richards (1906, p. 1216—1219). Symbol used: ._, absent] 1 2 a 4 5 6 7 8 9 10 Magnetite ______________________ 1,096 1,308 1 , 414 936 900 1, 176 40 72 8 822 Chromite _______________________ __ __ 150 __ __ __ __ 24 4 _- Ilmenite ________________________ 56 150 188 512 150 328 1,120 82 53 240 Garnet _________________________ 432 272 _ _ _ _ 600 320 424 _ - _ _ 20 Olivine _________________________ __ __ __ __ __ __ __ 1,597 118 __ Monazite _______________________ Trace 30 6 Trace Trace Trace Trace 71. 5 Trace Trace Zircon _________________________ _ _ 60 24 16 50 Trace 96 10 _ - Trace Quartz _________________________ 344 50 84 __ _- _- __ 12 1,330 396 Other minerals __________________ 72 30 132 536 300 17 6 1 120 1 122 487 1 520 1 Platinum bearing. 1—4. Concentrate from gravel. 1. Marcus, Stevens County. 2. Wilmont Bar, Columbia River, Ferry County. 3. Columbia River, Douglas County. 4. Snake River, Asotin County. 5. Concentrate from sand. 5. Snake River, Asotin County. 6-7. Undescribed source. 6. Brush Prairie, Clark County. 7. Clallam County. 8—10. Natural beach sand. 8. Moclips, Grays Harbor County. 9. Grays Harbor County. 10. Pacific County. WEST VIRGINIA AND WYOMING 271 TABLE 91.——Mineralogical composition of heavy fraction of sandstone of Paleozoic age in the J. L. Jamison well 1, M onongalia County, W. Va. ‘ [Modified from Martens (1939). Symbols used: VA, very abundant; A, abundant; C, common; 5, scarce; VS, very scarce; Ab, absent] 0 O Q) ., s s .5 F0 to b D th N E ° 5 7° 2 E3 °’ ° i=1 ma 1 n or mem er ep um- ,3 a: t .— (feet) ber of £3 8 5% 5 § :93 § E E = B ,, E ‘3 g § :5 ‘3 samples ‘5, 8 2 E 3: ‘3 5 88 $8 23 g E g g 5 1:4 2 an o N a: .3 a: U 9: <3 3: <1 2 N Buffalo and Mahoning ____________________________ 165-205 7 s A s C 0 vs C s vs vs s Ab s s Ab Allegheny _________________ _ 255485 18 VA 0 vs s C vs c s vs vs vs Ab vs vs Ab Pottsville ______ _._ 523-732 33 A C VS S A VS A S VS VS VS Ab VS VS VS Mauch Chunk- 732—964 16 C c vs s 0 vs A 0 vs vs vs Ab vs vs vs Greenbrier _____ 1,101—1,182 18 c vs Ab Ab A s A c s vs c vs vs vs Big Injun _________________ .. 1,197—1,250 11 c 3 Ab vs c vs A c s s Ab vs s vs vs Pocono below Big Injun__ _. 1,250-1, 762 45 A S Ab VS C S A C S S Ab Ab VS VS VS Catskill ___________________ ._ mamas 43 A s vs vs c vs A c s s vs Ab vs vs vs Chemung _________________________________________ 2,24%,077 62 A c s s c s c c s e vs Ab vs vs vs concentrations of monazite in Recent stream sediments 10+100 Screen size (mesh) Pgrzcent that have been reported are spatially associated with _100+206 """"""""""""""""" 17 the fossil placers. -200 _____________________________________ 31 rossrr. PLACERS or GAMBRIAN AGE Total ________________________________ 100 Occurrences of monazite in sluice concentrates and natural sand of the Bald Mountain district in the Big Horn Mountains, Sheridan and Big Horn Counties, Wyoming, were mentioned by Day and Richards (1906b, p. 1220—1221), and the report was repeated in 1917 by Schrader, Stone, and Sanford (1917, p. 346), but the source of the monazite was apparently unknown. Even the quantities of monazite observed in the sluice box concentrates and sand were a poor indication of the size and tenor of the source. The amount of monazite per short ton of concentrate or sand was found by Day and Richards and is indicated in the following table: Pounds per short ton Sluice-box Natural concentrate rand Magnetite __________________________ 1, 931 5 Chromite ___________________________ None 1. 2 Ilmenite ____________________________ 29 None Garnet _____________________________ None 17 Olivine _____________________________ None 1 Monazite ___________________________ 2 2 Zircon ______________________________ 37 3. 6 Quartz _____________________________ . 8 1, 592 Other minerals ______________________ None 376 Gold _______________________________ Present Present Total _________________________ 1, 999. 8 1, 997. 8 The source of the monazite from Bald Mountain was found to be a bed of quartz-pebble conglomerate at the base of the Deadwood Formation of Cambrian age where that formation rests on granite (McKinney and Horst, 1953, p. 7). Hematite and limonite in the matrix give the conglomerate a red cast. Associated with the monazlte in the quartzite are detrital ilmenite, magnetite, garnet, and zircon. About half of the monazite grains in the conglomerate of the Deadwood Formation are smaller than IOU-mesh (Borrowman and Rosenbaum, 1962, p. 3): Monazite from the Deadwood fossil placer is unusually rich in thorium oxide. Seven analyses by the US. Bureau of Mines showed an average of 8.8 percent of Th02 and 0.12 percent of U308 (McKinney and Horst, 1953, p. 25; Kauffman and Baber, 1956, p. 6; Borrow- man and Rosenbaum, 1962, p. 2): The composition was as follows: ThOZ, 8.68, 8.8, 8.8, 8.8, 8.9, 8.6, 9.2; U303, 0.10, 0.13, 0.12, 0.11, 0.11, 0.14, and 0.14. A drilling program by the US. Bureau of Mines in 1952 disclosed that the conglomerate at the base of the Deadwood Formation in the vicinity of Bald Moun- tain is 20—50 feet thick and contains 20 million short tons of rock averaging 2.5 pounds of monazite per short ton. Included in this average is a high-grade layer 2.5—10 feet thick immediately above the contact and estimated to contain 675,000 short tons of con- glomerate having 13.2 pounds of monazite per short ton (Borrowman and Rosenbaum, 1962, p. 2). FOSSIL PLACERS 0F LATE CRETACEOUS AGE Monazite-bearing titaniferous fossil placers of Late Cretaceous age have been observed in at least 13 places along the margins of intermontane basins in Wyo- ming (Murphy and Houston, 1955, p. 190—193; Chen- oweth, 1957, p. 212; Dow and Batty, 1961, p. 16-34:). These deposits are similar in origin to the Upper Cre- taceous titaniferous sandstones in the San Juan Basin of New Mexico and Colorado; however, the Wyoming deposits contain less monazite than the placers in the States to the south. Most of the fossil placers were formed as beach concentrates and represent the tran- sition from marine to nonmarine beds (Murphy and Houston, 1955, p. 190). The zones of concentration of heavy minerals consist of common ilmenite, anatase, and. rutile accompanied by magnetite, zircon, garnet, 272 monazite, tourmaline, epidote, staurolite, spinel, ilmen- orutile, and sphene with a cement of hematite and calcite. These zones of concentrated heavy minerals tend to be elongate, narrow, and thin like present-day beach deposits, and they were said by Murphy and Houston generally to occur with clean well-sorted massive sand stone beds of the littoral type. They do not extend for long distances; the longest deposits known reach a length of about 4 miles, and layers of black sand may be deposited at several stratigraphic horizons in one locality. Reports by Murphy and Houston (1955, p. 190—193) and Dow and Batty (1961, p. 16—34) showed that there were at least 19 placers at 13 localities in Wyo- ming. These 19 deposits were estimated by Dow and Batty (1961, p. 6) to contain 22 million short tons of titaniferous sandstone having an average tenor of 5.22 percent of TiOg, 0.55 percent of Z102, and 0.015 per- cent of eTh02. Similar deposits in New Mexico and Utah contain about 1a nine times greater percentage of eThOZ. The main fossil placer areas in Wyoming are the Bighorn Basin, Wind River Basin, and Rock Springs Uplift. Individual deposits are known in the Laramie Basin, Uinta Mountains, and near Cums berland Gap. Murphy and Houston stated that the fossil placers in the Bighorn Basin are in the basal part of the Mesaverde Formation, those in the Wind River Basin in sandstone in the Lewis Shale or its equivalent, and those in the Rock Springs Uplift in the lower part of the Ericson Sandstone. Poor ex- posure of the placer in the Laramie Basin makes iden— tification of the host rock doubtful, but it was thought by Murphy and Houston to be the Pine Ridge Sand- stone Member of the Mesaverde Formation. The fos- sil placer in the Uinta Mountains is in the Ericson Sandstone (Dow and Batty, 1961, p. 18), and the de- posit at Cumberland Gap is in the lower part of the Frontier Formation (Murphy and Houston, 1955, p. 190). Fossil placers in the Bighorn Basin are known as the Grass Creek North, Grass Creek South, Waugh, Mud Creek, Dugout Creek, Lovell, and Cowley deposits (Dow and Batty, 1961, fig. 1). The Grass Creek North deposit caps a cliff of Mesa— verde Sandstone about 1.5 miles northeast of Riverton, Hot Springs County, on the north limb of the Grass Creek anticline, and the smaller Grass Creek South deposit occurs on the south limb of the anticline about 3 miles southeast of the community of Grass Creek in Hot Springs County (Dow and Batty, 1961, p. 30—32). The two deposits seem to be erosional remnants of a single placer. Titaniferous sandstone at the northern deposit has an exposed length of 3,700 feet, width of THE GEOLOGIC OCCURRENCE OF MONAZITE 300 feet, and an average thickness of 8 feet. A com- posite of nine samples from the placer was reported by Dow and Batty to contain an average of 21.5 per- cent of T102, 3.0 percent of Zr02, and 0.09 percent of eTh02. At the southern deposit the titaniferous sand- stone is exposed for a length of 1,300 feet with an average thickness of 4 feet. Three samples from the outcrop averaged 15.6 percent of T102, 1.6 percent of Zr02, and 0.09 percent of 8Th02. According to Murphy and Houston (1955, p. 192), the heavy minerals at the Grass Creek fossil placer area, separated from matrix and magnetite, are as follows: Percent Ilmenite and anatase ________________________ 78 Zircon _____________________________________ 17 Garnet ____________________________________ 3 Rutile _____________________________________ 1 Monazite __________________________________ . 5 Tourmaline ________________________________ . 3 Total ________________________________ 99. 8 The nearby Waugh fossil placer was described by Dow and Batty (1961, p. 33) to be in Hot Springs County 16 miles southeast of the town of Grass Creek. The placer is 200 feet long, 150 feet wide, 4 feet in average thickness, and, as shown by one sample, con- tains 11.1 percent of Ti02, 1.5 percent of ZrOg, and 0.04 percent of eThOz. The Mud Creek fossil placer in Washakie County is 26 miles southeast of Worland (Dow and Batty, 1961, p. 28430). It was apparently formed by stream action instead of marine processes, because it occupies a channel in sandtstone of the Mesaverde Formation. Erosion by Mud Creek has divided the fossil placer into two parts which are exposed for 175 and 350 feet along the sides of the stream. The average thickness of the deposits is 6 feet and the maximum width is 200 feet. A composite of three samples of titaniferous sandstone from the Mud Creek placer contained 8.0 percent of TiOz, 0.5 percent of ZI'02, and 0.02 percent of eThOz. The largest fossil placer known in the Upper Cre- taceous rocks of Wyoming was reported by Dow and Batty (1961, p. 26—30) to be a channel deposit in sandstone of the Mesaverde Formation exposed at Dugout Creek in lVashakie County. Like the deposit on Mud Creek, the placer on Dugout Creek is also divided into two segments by stream erosion. The northern segment is exposed for a length of 5,300 feet and a width of 1,000 feet with an average thickness of 20 feet. Extensions toward the north and west are covered by younger rocks. The southern segment has an exposed length of 6,400 feet, width of 1,900 feet, and an average thickness of 18 feet. It is pos- SOUTH AME RICA sibly much larger. Analyses of samples from the out- crops of the two segments of the fossil placer disclosed the very low average of 0.01 percent of eThOz. The percentages of TiOz and ZrO2 were respectively 4.2 and 0.4. A fossil placer crops out on :a mesa 6 miles southeast of Lovell in Big Horn County (Dow and Batty, 1961, p. 26). It consists of a layer of titaniferous sandstone 3,700 feet long, 400—600 feet wide, and 2—12 feet thick. The single sample of titaniferous sandstone from this area that has been analyzed proved to be nonradio- active. Northwest of the Lovell deposit, a large low— grade mass of titaniferous sandstone is exposed on a mesa 1.5 miles southwest of Cowley, Big Horn Coun- ty. It is 2,500 feet long, as much as 600 feet Wide, and 2—6 feet thick. An analysis of one sample from the Cowley deposit disclosed 2.7 percent of Ti02, 0.2 percent of ZrOz, and 0.01 percent of eThOz (Dow and Batty, 1961, p. 26). Fossil placers near the east margin of the Wind River Basin are known at Clarkson Hill, Poison Spi- der, and Coalbank Hills, Natrona County (Dow and Batty, 1961, p. 22—26). The body of titaniferous sandstone at Clarkson Hill crops out about 27 miles west of Casper. It has an exposed length of 300 feet and an average thickness of 4 feet. Inasmuch as the exposure probably discloses the width of the deposit, its length may be much greater than 300 feet and its volume correspondingly large. Analyses of two sam— ples of the titaniferous sandstone showed an average of 9.7 percent of TiOz, 1.3 percent of Zr02, and 0.04 percent of eThOz. The Poison Spider fossil placer lo- cality is 30 miles west of Casper. The placer, in a sandstone member of the Lewis Shale, is exposed for a length of 300 feet and has a thickness of 4 feet. Percentages of Ti02, Zr02, and eThOz averaged from three samples are respectively 7.3, 0.7, and 0.03. The Coalbank Hills fossil placer is 17 miles southwest of Waltm-an. The placer has been eroded into two seg— ments which extend for 2,500 feet along the strike of the enclosing sandstone. Monazite seems to make up only a very small percentage of the heavy minerals, because a composite of five samples contained only 0.004 percent of eThOZ. Six fossil placers known collectively as the Salt Wells Creek deposits are exposed to the south-south— east of Rock Springs in the Rock Springs Uplift of Sweetwater County (Dow and Batty, 1961, p. 16—22). The deposits occur in the basal part of the Ericson Sandstone. They range in size from a body about 200 feet long and 3 feet thick of undetermined width to a layer of titaniferous sandstone about 2,500 feet long, 150 feet wide, and 7 feet thick. Monazite has 273 been observed as a minor constituent of the heavy suite, and analyses of the sandstone show from 0.04 to 0.1 percent of eThOz. In the Laramie Basin at the north end of Sheep Mountain 25 miles west of Laramie, Albany County, a fossil placer consisting of titaniferous sandstone is exposed for a distance of 525 feet (Dow and Batty, 1961, p. 22). The placer is considerably fractured. It is at least 15 thick and 60 feet wide. Monazite is a minor component of the placer, and an analysis of a composite of five samples revealed only 0.04 percent of eThOz. On the north flank of the Uinta Mountains 40 miles south of Rock Springs, the Red Creek fossil placer is exposed on the east side of Red Creek, Sweetwater County (Dow and Batty, 1961, p. 16). Titaniferous sandstone at the Red Creek deposit crops out for a length of 800 feet and 'a width of 100—200 feet through a maximum thickness of 8 feet. Monazite is a minor component of the sandstone, and the analysis of a composite of five samples of the sandstone showed only 0.04 percent of eThOz. Titaniferous deposits near Cumberland Gap, Uinta County, about 17 miles south of Kemmerer, are inter- mittently exposed for 22,000 feet in ridge-forming sandstone in the lower part of the Frontier Formation (Dow and Batty, 1961, p. 33—34). Although one of the deposits is 13 feet thick, the average thickness is only 5 feet. The fossil placers dip under younger for- mations; therefore, their size cannot be determined from surface exposures. Monazite in small amounts accompanies the other heavy minerals, but the heavy- mineral-bearing zones are difficult to distinguish from the rest of the sandstone because the entire sandstone is dark brown to bufi'. Samples from the outcrop con- tain less than 0.01 percent of eT1102. RECENT ALLUVIAL DEPOSITS In addition to the occurrence of monazite in Recent alluvial deposits in the vicinity of the fossil placers of Cambrian age in the Bald Mountain district, pre- viously mentioned, the mineral has also been reported from a locality along the Green River, Sweetwater County, where Day and Richards (1906b, p. 1220— 1221) found a trace of monazite in a short ton of natural sand. SOUTH AMERICA The many placers in marine beaches and elevated bars along the south coast of Brazil were the world’s main source of commercial monazite from 1895 through 1913. They still constitute one of the larger known sources, but new discoveries in North America, Africa, and Asia considerably lessen their international im- 274 portance. Placers along the coast of Uruguay resemble the Brazilian deposits. Fluviatile and primary de- posits of monazite in the interior of Brazil constitute an immense resource. ARGENTINA The descriptive lists of Argentine minerals compiled by Ahlfeld and Angelelli (1948), Angelelli (1950), and Amato (1956, p. 51—69) did not include references to monazite, but as early as 1889 this mineral had been re- ported among the accessory heavy minerals in decom- posed granite and gneiss at Cordoba, Cordoba Province (Derby, 1889, p. 113). In 1962 a discovery of over 30 million tons of sand said to contain 7 percent of heavy minerals, including a small amount of monazite, was reported in Cérdoba Province, but the nature of the occurrence was not described (Eng. and Mining J our., 1962). According to Angelelli (1956, p. 63, 67), masses of monazite have been found in pegmatite dikes which intrude gneiss of Precambrian age at the Sierra de Valle Fértil, San Juan Province. The sizes of the masses and the amount of monazite in the dikes were not described. Detrital monazite associated with zircon was ob~ served in sand along the banks of the Rio de la Plata at Buenos Aires on the Argentine side and at Punta Caballos on the Uruguayan shore (Derby, 1889, p. 113; J ohnstone, 1914, p. 58). Alluvial gold and tin placers at Orosmiayo, Rio Cincel, Rio del Candado (Rio Can- dado), and elsewhere in the interior of Argentina were stated to contain monazite (Angelelli, 1956, p. 65—67). Sand in Riocito (Riecito Stream) at La Carolina in San Luis Province contains monazite (Mining World, 1952). Monazite probably occurs locally along the At- lantic beaches of Argentina. An output of 1 ton of monazite in 1956 was reported for Argentina (J. G. Parker, written commun. 1962). BOLIVIA Crystals of monazite weighing as much as 7 pounds have been found in columbite—bearing muscovite peg- matite exposed 3 miles north of Mina Verde near San Agustin, Santa Cruz, Bolivia (Hinckley, 1945, p. 16; Ahlfeld, 1954, p. 229; Ahlfeld and Munoz Reyes, 1955, p. 135). The area is underlain by granite, gneiss, and schist; many pegmatite dikes are in the granite. The pegmatite dikes are composed mainly of feldspar, usually weathered to kaolin, and quartz. They commonly have quartz cores. Monazite—bearing pegmatite dikes have columbite in the core and musco— vite in the wall zone, but the position of the monazite was not indicated. The monazite is a minor accessory mineral and is less abundant than the columbite. An THE GEOLOGIC OCCURRENCE OF MONAZITE analysis of the monazite showed that it contained the amount of thorium oxide shown: [Analyst R. Herzenberg (in Ahlfeld, 1954, p. 229)] Percent 52. 2 10. 1 (Ce, La) 203 ________________________________ Th02 ______________________________________ Near Sorata, a molybdenite—bearing pegmatite dike in granite intrusive into quartzite questionably con- tains monazite (Ahlfeld and Mufioz Reyes, 1939, p. 106). Monazite was dubiously reported (Ahlfeld and Mufioz Reyes, 1955, p. 135) in tin deposits at Cho- rolque, La Union, and Huayna Potosi. Monazite was reported by Beard (1930, p. 109) and Ahlfeld (1931, p. 249) to be a rare accessory mineral and by Gordon (1944, p. 286—301) to be a common but minor accessory mineral in the cassiterite veins at Cerro de Llallagua. At Llallagua an elliptically shaped body of quartz porphyry intrudes graywacke and shale of Devonian age. The porphyry and the sedimentary rocks for a distance of 1,000 feet from the porphyry are extensively altered to muscovite, tour- maline, and quartz. After the porphyry and gray- wacke were hydrothermally altered, fissures formed normal to the long axis of the body of porphyry, and pneumatolytic solutions deposited the vein-forming minerals. Most of the veins are in the porphyry, but a few are in the graywacke and shale. The veins are vuggy, and the vein minerals seem to have been depos- ited in open fissures. The sequence of mineralization is interpreted by Gordon (1944, p. 300—301) to have begun with the growth of quartz crystals on the walls of the fissures. The quartz was followed by bismuth- inite, cassiterite, wolframite, apatite, monazite, and pyrrhotite. As the temperature of the solutions de- creased, the pyrrhotite was replaced by marcasite, franckeite, wurtzite, galena, pyrite, siderite, sphalerite, and stannite. Apatite is the main gangue mineral in many veins. The monazite is flesh pink, and occurs as translucent prisms, twinned crystals, and coarse granu- lar aggregates intergrown with cassiterite and as small twin crystals overgrown on prismatic quartz in vugs. A chemical analysis showed that the monazite is devoid of thorium: [Analystz Gordon in 1939 (in Gordon, 1944, p. 330)]. Percent Ce203 (group) ______________________________ 31. 41 La203 (group) ______________________________ 33. 19 Y203 ______________________________________ 5. 08 Th02 ______________________________________ . 00 P205 _______________________________________ 29. 29 SiOz _______________________________________ . 27 CaO ______________________________________ . 34 MgO ______________________________________ . 22 Total ________________________________ 99. 80 SOUTH AMERICA The specific gravity of this monazite was determined as 5.173 by Parrish (1939, p. 652). The absence of thorium was confirmed by spectrographic analysis and examination with a Geiger—Muller counter (Gordon, 1944,p.330) N0 monazite has been produced in Bolivia. BRAZIL The first notice of monazite in Brazil appeared in a report by Gorceix (1883, p. 32). He found yellow grains, which he tentatively identified as monazite, in sand reputed to have come from streams around the Fazenda Quebra-Cangalha in S50 Paulo, but which he later said originated near Caravelas, Bahia (Gorceix, 1884a, p. 182). During 1884 and 1885 Gorceix con- firmed the identity of the mineral as monazite, and he extended its known distribution in Brazil to the State of Minas Gerais where he found it in diamond placers at Diamantina (Gorceix, 1884b, p. 1446; 1885a, p. 29— 30) and in gold placers along tributaries to the Rio Doce near Casca (Gorceix, 1885a, p. 36), and to the State of Bahia in the vicinity of Salébro (Gorceix, 1884b). Some time between 1885 and 1890, John Gordon commenced to mine monazite sand on the coast of Bahia between Canavelas (Caravellas) and Prado. By 1890 when the local government temporarily halted the mining, according to Leonardos (1937a, p. 3), Gordon had shipped 15,000 tons of monazite concentrate to Europe. There is no independent verification of this estimate. In 1895 monazite mining was resumed, and 3,000 tons of concentrate produced in Bahia was ex- ported during 1893-95 (Freyberg, 1934, p. 378). After 1895, beach placers were mined in Bahia, and new placers were opened in Espirito Santo and Rio de J an- eiro along the Atlantic coast south of Bahia. Demand for monazite as a source for thorium and later for the rare earths (Drouin, 1911) led to a Brazilian output which reached a peak of 7,121 short tons in 1909 and totaled at least 85,827 tons by 1949 (Mertie, 1953, p. 6). After 1914 Brazil fell behind India as the leading pro- ducer of monazite. Monazite marketed from Brazilian beach placers contains from 5.0 to 6.49 percent of Th02 (Copland, 1905, p. 6; Metall. and Chemical Eng, 1915, p. 403). Most writers are agreed that the Brazilian commercial monazite averages 6.0 percent of Th02 (Kremers, 1958, p. 2; Krusch, 1938, p. 73; Wadia, 1944, p. 6; Mat- tos Netto, 1951, p. 186; Johnstone, 1914, p. 58), but a slightly lower average of 5.5 percent of ThOZ is fav- ored by B-arbosa (1948, p. 10). Representative com- mercial analyses are in the table that follows. Several old analyses of monazite from the beaches of Espirito Santo show low abundances of thorium 275 Chemical analyses, in percent, of monazite from Brazilian beach placers [Analysts: 1, F. H. Lee (in Metall. and Chemical Eng., 1915, p. 403); 2. Commercial average (in Kremers, 1958, p. 2); 3, Johnstone (1914, p. 58)] 08203 __________________________ (La, Nd, Pr)203 _________________ Loss on ignition _________________ . 20 Total ____________________ oxide compared to the average. A partial analysis of such material was made by Guilherme Florence in 1913 and was published by Furia (1939, p. 31). It showed 3.096 percent of Th02. Freise (1910a, p. 53—54) quoted an analysis given by Richardson in the Brazil- ian Mining Review for July 1903 which showed 1.48 percent of Th02 in a product obviously contaminated with quartz and zircon. Similar low abundances of thorium oxide were reported as far north as Bahia (Leonardos, 1937a, p. 12) for material called monazite or monazite sand which is of widely variable mineral composition. Radium was identified in salts from Brazilian monazite as early as 1904 (Haitinger and Peters, 1904). The immediate source of the monazite along the At- lantic beaches of Brazil are consolidated sedimentary rocks of Cretaceous age (Brazilian Eng. and Mining Rev., 1905, p. 153) and the B'arreiras sedimentary se— ries of Tertiary age (Oliveira, Avelino, 1956, p. 56—59). The ultimate source of the placer monazite is the plu- tonic complex of the Brazilian Shield. CRY'STALLINE ROCKS AND FLUVIAL DEPOSITS The crystalline rocks in Brazil were discovered early to contain accessory monazite. Derby (1889, p. 110) described how he had panned monazite from gneiss exposed in the Serra de Tijuca, at the city of Rio (16 J aneiro, and about a dozen places in the States of Rio de J aneiro, Minas Gerais, and Sao Paulo. Use of the gold pan to concentrate monazite led Derby and other geologists to discover the mineral in bedrock and stream sand not only in those states just mentioned and also in the States of Espirito Santo, Bahia, Par- aiba, Rio Grande do Norte, Goias, and Mato Grosso. mo DE JANEIRO Gneiss, granite, and pegmatite are locally, possibly widely, monazite-bearing in the State of Rio de Janeiro. In the city of Rio de J aneiro, sillimanite- 276 and cordierite-bearing gneisses contain monazite (Ri- mann, 1917, p. 21). Apatite—rich gneiss and silicic granite at Serra de Tijuca, a peak in the Serra do Mar near the city of Rio de Janeiro, and gneisses in the Serra do Mar were reported by Derby (1889, p. 110— 112) to have monazite. The granite from Serra de Tijuca contains 0.02—0.03 percent of monazite (Hintze, 1922, p. 350; Moraes, Leonardos, and Lisboa, 1937, p. 546). A monazite—bearing fine-grained granite dike is exposed near J acarepagfia on the outskirts of the city of Rio de J aneiro (Derby, 1889, p. 113). The dike, which contains 0.07 percent of monazite and zircon, has the highest tenor in monazite of any rock examined by Derby (Hintze, 1922, p. 350). In the vicinity of Rio de J aneiro, monazite occurs as microscopic grains in granitic gneiss intruded by pegmatite at Niteroi (Nitcheroy) (Leonardos, 1937a, p. 9) and in biotite granite which intrudes gneiss at Barra do Pirai (Barra do Piraley, Bassa do Pirahy). At this locality both the gneiss and the granite contain monazite (Derby, 1889, p. 113), but it is uncommonly abundant in the granite and is accompanied there by allanite (Hintze, 1922, p. 350). Monazite is virtually the sole accessory mineral accompanying massive graphite in a graphite- rich layer in gneiss at Sac F idelis (Derby, 1902, p. 212). Granite at Consersatéria (Conservatoria) was reported by Eugene Hussak (1891, p. 472) to contain monazite. In the same area at Santa Isabel do Rio Preto garnetiferous gneisses and samarskite-bearing pegmatite dikes have accessory monazite (Barbosa, C. D., 1948, p. 7, 9—10; Catrifi, 1951, p. 290). Streams draining the area transport detrital monazite, garnet, and ilmenite. The detrital monazite contains 7.2—7.5 percent of ThOz (Barbosa, C. D., 1948, p. 10). Sa- marskite—bearing pegmatite dikes exposed around Pa- raiba do Sul, Rio Bonito, and Crubixais (Glicerio) contain small amounts of monazite (Catrifi, 1951, p. 290). $110 PAULO Monazite was found in crystalline rocks at many 10- calities in S7ao Paulo by Derby (1889, p. 111—113) fol- lowing its initial discovery by Gorceix (1883, p. 32) in stream sand at the Fazenda Quebra—Cangalha. Monazite is an accessory mineral in sillim'anite gneiss at Cotia (Cutita) and in syenite at San J oas. It oc- curs in muscovite granite at Caieiras in well-formed crystals 0.1 inch across (Hussak, 1891, p. 471). Musco- vite granite at Sorocaba was found by Derby (1889, p. 111—112) to contain monazite. Biotite granite at Pie- dade, biotite-muscovite gneiss at Santos, and biotite granite and gneiss at Boa Vista on the Rio Ribeira de Iguapa contain accessory monazite. Accessory monazite eroded from granite gneiss and THE GEOLOGIC OCCURRENCE OF MONAZITE pegmatite occurs as a minor detrital constituent of continental sand and conglomerate of Tertiary and Re- cent age deposited in the upstream parts of the Rio Paraiba and Rio Paraibuna, and in the vicinity of 85.0 J osé dos Campos, Sao Paulo (Engenharia, Mineragao e Metalurgia 1956; Leonardos, 1937 a, p. 9). At Itape- cerica da Serra (Itapecerica), detrital monazite was found at the base of sediments of Pliocene or Pleisto— cene age, and at various unspecified localities in the interior of 85.0 Paulo detrital monazite was observed in sand of Mesozoic age (Engenharia, Mineragao e Metalurgia, 1956). Monazite from decomposed granite at the Fazenda Recreio southeast of Pinhal, Sio Paulo, was analyzed about 1908 by Guilherme Florence and was found to contain 1.99 percent of Th02 (Furia, 1939, p. 31). The inner and outer parts of a large crystal of monazite from pegmatite at Grama, Sio Paulo, were analyzed for rare earths and thorium oxide in 1957. The orig- inal analyses of the core were published as percentages of the total rare earths plus thorium oxide precipitate equal 99.9 percent. The analysis was recalculated to 71.1 percent total rare earths plus thorium oxide in the monazite (H. J. Rose, J r., written commun., 1958). The original analysis of the outer part was published as percentages of the total rare earths plus thorium oxide precipitate equal 100.4 percent. The analysis was recalculated to 70.74 percent total rare earths plus thorium oxide in the monazite (H. J. Rose, J r., writ- ten commun., 1958). The core of the crystal contained 11.6 percent of ThOz, and the outer part contained 10.93 percent: Analysts: K. J. Murata and H. J. Rose, Jr. (in Murata and others, 1957, p. 148)] Percent Core Outer part CeOZ _____________________________________ 24. 7 24. 88 143.203 ___________________________________ 8.1 8. 46 Nd203 __________________________________ 14. 7 14. 17 PI'sOu __________________________________ 3. 7 3. 73 Sm203 __________________________________ 3. 6 3. 45 Gd203 __________________________________ 1. 6 1. 76 Y203 _____________________________________ 3. 1 3. 36 Th0; ___________________________________ 1]. 6 10. 93 Total _____________________________ 71. 1 70. 74 Another large crystal of monazite from a pegmatite at Grama contained 11.4 percent of ThOz (Murata, Dutra, and others, 1958, p. 7). Attempts have been made to mine monazite from river sands in the interior of 85.0 Paulo, but the efforts were abandoned because the crude sand contained only 2 percent or less of monazite (Gottschalk, 1915, p. 903). mums exams Crystalline rocks, particularly pegmatite, in the State of Minas Gerais have been extensively sampled, SOUTH AMERICA and monazite has been reported for many of these samples. The coastal range of Minas Gerais about 100 miles northwest of Rio de J aneiro exposes monazite- rich granite associated with gneiss and schist (Draper, 1911, p. 10). Sillimanite gneiss at Sosségo (Socego) on the border between Minas Gerais and Rio de J an- eiro contains monazite (Derby, 1889, p. 111-112). Muscovite-bearing pegmatites at several localities in Municipio Juiz de Fora and the enclosing schists are monazite-bearing. Analyses of five samples of mona- zite taken between the wallrock and the quartz core of the pegmatite at the Roga Grande mine near Ibitiguaia disclosed that the T1102 ranged in abundance from 9.7 percent near the wallrock to 15.3 percent about halfway between the wallrock and the core and 11.4 percent adjacent to the core (Murata, and others, 1958, p. 7). The average abundance of ThOZ was 11.6 per— cent. Monazite from the schist at the mine contained 3.3 percent of ThOZ. At a pegmatite in the Linhares mine in the same municipality, small monazite crys- tals near the wallrock contain 9.4 percent of ThOz (Murata and others, 1958, p. 7). A layer of graphite in granitic gneiss cropping out in the bed of the Cérrego do Emparedado about 65 miles downstream along the Rio J equitinhonha from Arassuai (Arassuahy) has abundant accessory mona- zite (Derby, 1902). The layer of graphite consists of 85 percent of carbon, 4.7 percent of volatile matter, and 7.2 percent of ash. The principal constituent of the ash is monazite. Derby noted that the monazite was in a state of strain and that it fell to pieces while he panned it out of the graphite. This occurrence and one of monazite-bearing graphite from gneiss near Silo Fidelis in Rio de J aneiro prompted Derby to in- vestigate several samples of graphitic sericite schist from the two states. Inasmuch as he found no mona- zite in the graphitic sericite schist, whereas it was abundant in graphite layers from granite gneiss, Derby (1902, p. 212) concluded that the presence of monazite depended on the origin of the rock. He implied that monazite is present in graphite layers in gneisses of igneous origin and absent from graphite layers in schists of sedimentary origin. How the grade of meta- morphism influences the amount of monazite seems not to have been considered by Derby. Large crystals of monazite from pegmatite at Coro- nel Murta contain 9.1 percent of Th0. (Murata and others, 1958, p. 7). The diamond—mining district of Diamantina, Minas Gerais, has many localities where monazite has been found. The district extends about 100 miles north- eastward from Datas (Dattas) along the west side of the Rio Jequitinhonha. According to L. S. Thomp- 277 son (1928, p. 707—709), schists of the basement com- plex in the Diamantina district, the Itacolomi series of late Precambrian age (Moraes and Guimaraes, 1931, p. 503; Oliveira, Avelino, 1956, p. 19), are unconform- ably overlain by a cleaved and schistose quartzite which has a bed of conglomerate near the base. The conglomerate is 30—80 feet thick. It rests directly on the basement complex in the northern part of the dis- trict, but to the south around Datas the conglomerate is separated from the basement by at least 300 feet of quartzite lithologically identical to the overlying quartzite. Pebbles in the conglomerate have a wide range in composition, but quartz and quartzite are most common. The quartzite and conglomerate are part of the monazite— and diamond-bearing mesozon- ally metamorphosed Lavras series of Cambrian age (Moraes and Guimaraes, 1931, p. 503; Leonardos, 1937a, p. 9; Oliveira, Avelino, 1956, p. 19—20). The quartzite, conglomerate, and basement rocks are cut by mafic dikes and elliptically shaped masses of igneous breccia. The masses of breccia have nearly vertical walls and sharp contacts in the quartzite. The breccia consists of blocky fragments of quartzite in a matrix of mafic igneous rock similar to the dikes. Fragments of quartzite are oriented with their long axes parallel to the vertical walls of the breccia masses. No igneous alteration of the inclusions was seen. Un- conformably overlying the quartzite, breccia, and mafic dikes are patches of poorly sorted conglomerate, sand, and silt of Tertiary or Pleistocene age. The rocks are thoroughly weathered to depths as great as 300 feet below the present surface of the land. Mafic dikes exposed in the Barro-Duro opencut near $5.0 J 050 da Chapada in the Diamantina district were reported by L. S. Thompson (1928, p. 709) to contain monazite. Sheared diabase and soft greenish schist from a mine at sea Joao da Chapada, probably the same opening visited by Thompson, had previously been found by Derby (1899, p. 348; 1900a, p. 209—213) to be monazite-bearing. The concentrate obtained by Thompson consisted of rutile, anatase, ilmenite, kya- nite, tourmaline, monazite, and magnetite. None of the minerals was abraded. A similar concentrate was panned by Thompson from the matrix of one of the igneous breccias. Derby remarked that the greenish schist had practically no free quartz and that similar monazite-bearing mafic dikes were exposed near Datas at the south end of the district. These were the only outcrops of mafic rocks in Brazil from which Derby obtained monazite. He regarded the occurrences as unlike any elsewhere reported. Partially altered and corroded crystals of monazite and xenotime were recovered from the heavy residues 278 of lazulite-rich nodules in the quartzite in the Diaman- tina district (Derby, 1891a; 1891b; 1899, p. 350—351). Derby thought that the lazulite, which is a common secondary mineral in the quartzite, might have been liquid inclusions. In the Perpetua deposit at 813.0 Joao da Chapada, diamondiferous sericite phyllite formed by cataclastic deformation and alteration of laminated, conformable, muscovite-bearing granitic rock intrusive into the Itacolomi series contains abundant accessory hematite, and less common magnetite, tourmaline, monazite, xenotime, and rutile. The relative abundance of the main accessory minerals is shown by the composition of a concentrate panned from 20 cubic meters of rock from which 2 carats of diamonds were recovered (Morase and Guimaraes, 1931, p. 524): Percent Quartz ____________________________________ 30. 9 Hematite __________________________________ 62. 7 Magnetite _________________________________ 1. 0 Tourmaline ________________________________ 1. 1 Monazite __________________________________ 4. 3 The monazite in this materail consists of crystal fragments thought by Moraes and Guimaraes to have been formed during the cataclastic deformation of the original granitic rock. Other rocks in the district that contain monazite are chlorite-kyanite phyllite or schist which crops out near the Serra do Gigante several miles to the north of 85.0 Joao da Chapada and saprolite of sericite schist from Sopa (Derby, 1899, p. 348—351; 1900b, p. 220). The phyllite contains many enormous crystals of kyanite in an imperfectly laminated groundmass of chlorite. The rock is rich in monazite, and the mona- zite, like the chlorite and kyanite, contains numerous minute grains of rutile. The sericite schist at Sopa may be the metamorphic derivative of, a porphyry (Derby, 1900b, p. 221). Near the large diamond mine at $50 Joao da Chapada in a small gold mine called Ogé, monazite is associated with rutile and bright green muscovite in a quartz vein in diabase. Aurifer- ous quartz veins in the neighborhood of Diamantina, which, according to Hintze (1922, p. 354—355), are probably genetically related to pegmatitic granite, contain thorium-bearing monazite full of gaseous and derived from original clastic phosphate. A gold placer at Bandeirinha on the Riacho Varas in the vicinity of Sopa and 823.0 J 05.0 da Chapada contains monazite of a peculiar prismatic habit which is filled with scales of hematite and minute needles of rutile (Derby, 1900b, p. 219; Smith, H. 0., 1896, p. 372; Hintze, 1922, p. 354). The monazite was traced by Derby to sericite phyllite. In the placer the monazite is accompanied by crystalline unrounded gold, euhedral THE GEOLOGIC OCCURRENCE OF MONAZITE xenotime, prismatic colorless zircon, needles of black tourmaline, limonitized pyrite, magnetite, and mica (Hussak and Reitinger, 1903, p. 560). An average of two analyses of the monazite showed that it contained 1.09 percent of Th02 and that it had a specific gravity of 4.96; monazite from the valley of the Riacho Varas was said to contain no thorium and had a specific gravity of 5.2: [Analystz A, J. Reitinger (in Hussak and Reitinger 1903, p. 560); B, J. Reitinger (in Hintze, 1922, p. 370)i Percent A B Ce203 __________________________________ 32. 46 33. 9 (La, Pr)203 ______________________________ 19. 21 Nd203 __________________________________ 16. 81 36' 6 Th02 ___________________________________ 1. 09 . 00 P205 ___________________________________ 29. 18 30. 00 F6203 __________________________________ . 61 _______ CaO ___________________________________ . 10 _______ Total _____________________________ 99. 46 100. 5 A. Bandeirinha. Average of two analyses. B. Riacho Varas. Concentrates containing possibly 80 percent of monazite and said to have come from a stream in the Diamantina area have 11.16 percent of Th02, 24.57 percent of P205, 29.49 percent of CeZOS, 3.62 percent of La203 (group) and 10.96 percent of SiOz accord- ing to an incomplete analysis given by Freise (1911, p. 258). Elsewhere in the Diamantina district, monazite has been reported from undescribed bedrock, diamond mines, and stream sediments at Pagao, Campo do Sampaio, Perpetua (Moraes, Barbosa, and others, 1937, p. 132), and Milho Verde in the headwaters of the Rio J equitinhonha where that river is called the Rio das Pedras (GorceiX, 1884a, p. 182; 1885a, p. 29). Monazite, according to L. S. Thompson (1928, p. 709), is a rare member of a group of minerals that accompanies diamonds wherever they are found in the Diamantina district. Other rare members of the group are zircon, staurolite, and corundum. Quartz crystals, opalescent quartz, rutile, anatase, ilmenite, and kyanite are the common minerals associated with the dia- monds, and less commonly magnetite, hematite, garnet, and tourmaline appear. These minerals are said by Thompson to be rolled and worn in appearance where they are derived from placers regardless of the age of the placer, and they are said to have a fresh, clear- cut appearance where derived from the diamondifer- ous igneous. breccias and dikes. Placers of at least three ages are recognized by L. S. Thompson (1928, p. 709). The youngest are alluvial placers in the ter- races, flood plains, and beds of the present streams, and eluvial placers in the residual soil. Somewhat older deposits are the fossil placers in sediments of Tertiary or Pleistocene age. The oldest deposits are SOUTH AME RICA the fossil placers in the quartzite. Thompson’s gen— eralization that only round and abraded heavy miner- als are found in the present alluvium and in the old quartzite is, with respect to monazite, not entirely in accord with the observations of other writers (Derby, 1898). Good crystals of monazite, as much as 0.4 inch long, have been taken from the diamond-bearing alluvium at Datas and were used by Busz (1914, p. 482-483) for a study of the form and optical properties of monazite. In a gold placer at Bandeirinha, mentioned above, prismatic crystals of monazite are accompanied by unrounded crystals of gold (Derby, 1900b, p. 219; Hussak and Reitinger, 1903, p. 560). A clear description of the fresh appearance of mona— zite from metamorphosed conglomerate at the Cavallo Morto diamond mine near Diamantina was given by Derby (1900b, p. 218—219). His observations of mona- zite in the Cavallo Morto mine and in chlorite-kyanite phyllite at the Serra do Gigante led him to conclude that monazite can form both as an igneous and as a metamorphic mineral (Derby, 1900b, p. 219—220). This important inference was subsequently ignored. The Diamantina area is evidently one in which monazite has a wide variety of habitat including un- usual occurrences in mafic rocks, low- and high-rank metamorphic rocks, veins, and lazulite nodules. The pegmatite districts of Minas Gerais have sup- plied many samples of monazite for study, but they apparently include no commercial monazite deposits. Cassiterite- and tantalite—bearing pegmatite dikes in the S50 Joao del Rei area of Minas Gerais contain monazite (Belezkij, 1956, p. 2—15;; Guimaraes and Belezkij, 1956; Guimaraes, Djalma, 1956; Rolfl', 1947; 1948, p 16; Vaz, 1948, p. 26). The dikes are emplaced in granite gneiss and gneiss. According to Belezkij, cassiterite is the principal economic mineral in the district, and most of the cassiterite is in pegmatite in the basin of the Rio das Mortes west of the city of SEC Joao del Rei. Around the city auriferous quartz veins are common, and north of the city in the vicinity of Santa Rita do Rio Abaixo are stan- niferous pegmatite dikes and veins containing mona— zite, xenotime, and fergusonite. Medium-grained light-gray gneissic granite exposed on the Morro do .Rezende and in the Rio das Mortes contains mona— zite (Belezkij, 1956, p. 6—9). The rock consists of quartz, biotite, microcline, oligoclase, albite, monazite, titano-magnetite, sphene, epidote, zoisite, muscovite, and zircon. The monazite and zircon are rounded and are included in the other minerals. Because of the round shape of the zircon and monazite, and the 279 abundance of quartz in the rock, the gneiss is said to have been metamorphically derived from an arenaceous tufi'aceous sediment under mesozone conditions and subsequently granitized. Questionably identified mon— azite was seen by Belezkij (1956, p. 15) in cataclastic biotite gneiss exposed between the village of Cassi- terita and the Rio das Mortes Pequeno. Large crystals of monazite from a pegmatite in the 850 J 050 del Rei district contain 17.0 percent of Th02 (Murata and others, 1958, p. 7). Eluvial monazite concentrate from the Fazenda da Barra on the Rio das Mortes in the sac J 05.0 del Rei district was analyzed by Peixoto and shown to have 6.22 percent of Th02 where fresh and 5.73 percent where somewhat weathered (Peixoto and Guimaraes, 1953, p. 24) : Percent Fresh Weathered C6203 ______________________________ 38. 08 _________ Lagos ______________________________ 9. 53 _________ Gd303 ______________________________ Trace _________ Y203 _______________________________ 10. 15 _________ Th02 _______________________________ 6. 22 5. 73 U308 _______________________________ Trace 0 P305 ________________________________ 25. 75 _________ SiOz ________________________________ 1. 09 _________ A1203 _______________________________ . 49 . 90 FeO _______________________________ 2. 07 _________ TiOg _______________________________ . 17 _________ CaO _______________________________ . 02 _________ MgO _______________________________ Trace _________ MnO _______________________________ . 29 _________ PbO _______________________________ . 16 . 15 $110 ________________________________ . 33 _________ ZrOz _______________________________ Trace _________ T2405 ______________________________ . 64 _________ Nb205 ______________________________ 4. 72 _________ K20 + NaqO __________________________ Trace _________ H20 ________________________________ . 40 . 60 Total _________________________ 100. 1 1 _________ Samples of monazite from pegmatite, eluvium, and alluvium in the 85.0 Joao del Rei area were analyzed for thorium oxide by Alexandre Girotto with the follow- ing results (Rolff, 1948, p. 18): Th0: Source (percent) Fazenda Rochedo ______________ Pegmatite _________ 10. 80 Ribeirao J aburu _______________ Eluvium __________ 8. 74 Fazenda Fundao _______________ Eluvium __________ 9. 32 Mato Virgem __________________ Pegmatite ......... 7. 00 Ibatuba (Soledade) ____________ Pegmatite _________ 7. 66 Ibatuba ______________________ Eluvium __________ 6. 85 Ibatuba ______________________ Alluvium __________ 7. 50 Placers throughout the 85.0 J 050 del Rei area contain monazite derived from the gneiss, granite, pegmatite, 280 and veins. Monazite from a stream at Ibatuba was reported to have the following composition: [Analystz C. M. Pinto (in Arafijo, 1948, p. 48)] Percent Percent 06203 ________________ 28 50 A1203 ________________ 0. 21 (Nd, Pr)203 ___________ 29. 20 Fe203 ________________ .65 (Y, Er)203 ____________ 3. 80 CaO _________________ .36 ThOZ ________________ 7. 60 Loss on ignition _______ 1. 36 P205 _________________ 24. 80 8102 _________________ 2. 95 Total __________ 99. 43 A rather similar analysis was reported for monazite from Minas Gerais, but the exact geologic and geo— graphic source was not given: [Analyst: Kato (1958, p. 226)] Percent Percent 08203 _______________ 28. 43 F8203 _______________ 2. 88 LazOg _______________ 32. 49 C20 ________________ . 02 Th02 _______________ 5. 37 PbO ________________ . 09 U303 ________________ Trace Loss on ignition ______ . 46 P205 ________________ 28. 57 —————— SiOz ________________ 1. 18 Total _________ 100. 57 A1203 _______________ 1. 08 Monazite from pegmatite at Rochedo, Municipio de Resende Costa, Minas Gerais, includes minute grains of tantalite, cassiterite, and feldspar and contains as much as 9.19 percent of ThO2: [Analystz Peixoto (in Peixoto and Guimaraes, 1953, p. 22)] Percent Percent 0e203 (group) ________ 55. 60 CaO ________________ 0. 06 Laos _______________ Trace MgO _______________ . 06 Th02 _______________ 1 9. 19 MnO _______________ . 01 U303 ________________ . 12 PbO ________________ 2 . 44 P205 ________________ 26. 33 $1102 ________________ . 63 SiOZ_ _______________ . 35 1‘3205+ NbgO5- _ _ _ _ _ - 1. 98 A1203 _______________ 4. 18 H20 ________________ 3 1. 10 Fegoa _______________ 4. 04 —-—— T102 ________________ . 02 Total _________ 4 104. 11 1 Weathered sample contains 8.88 percent of Th02. 2 Weathered sample contains 0.41 percent of P130. 3 Weathered sample contains 1.47 percent of H20. 4 Given as 100.11 percent. Monazite is associated with beryl, columbite, and annerodite in a pegmatite dike at Gruta da Generosa near Sabinépolis (Leonardos, 1936a; 1936b, p. 16‘17; 1937a, p. 9; Catrii’i, 1951, p. 289). The dike is 10 feet thick, is emplaced in biotite gneiss, and consists of microcline-perthite and a quartz core. Books of mus- covite accompany the feldspar. Monazite is thought by Leonardos to have been the first mineral to crystal- lize, and it was followed by columbite, annerodite, beryl, muscovite, microcline, fluorite, and quartz. Al- though monazite makes up less than 0.01 percent of the pegmatite, some crystals of monazite weigh as much as 2.5 pounds. The monazite is rich in thorium oxide, but an early analysis cited by Leonardos that showed 20.2 percent of Th02 is not supported by later analyses given by Peixoto and Guimaraes and Murata and associates, which show 8.02—9.4 percent. THE GEOLOGIC OCCURRENCE OF MONAZITE Chemical analyses, in percent, of monazite from Gruta da Generosa [Analysts: 1, Escola de Minas de Ouro Preto (in Leonardos, 1936a, p. 16);2—4, Peixoto (1135183eix07to and Guimaraes, 1953, p. 23); 5—6. Murata, Dutra, Costa, and Branco , p. ). Symbol use’lz __, not determined] 1 2 3 4 5 6 51.06 { 33-12 - - ~ __ .35 ._ _. __ __ 20. 20 8.55 8. 16 8. 02 9. 4 8. 7 .16 .30 .20 .19 _ __ 22. 21 22. 23 _. _ _ __ . . 3.28 2.12 __ __ ._ __ ._ .89 1.07 1.21 __ _. ._ .26 _. __ .r _. 1.46 __ __ __ __ ._ __ .19 __ ._ __ _. .07 _ c __ _ .02 ._ u . _ .01 N ._ _. .09 .10 10 _ _. .09 _ _ ._ __ Trace . . __ ._ .03 __ A __ __ 1.62 .29 _. .. . __ 99.99 99.33 ________________________________________ A weathered pegmatite in the Divine de Uba dis- trict, Minas Gerais, has been mentioned several times in the literature for its large crystals of monazite. As originally described by Djalma Guimaraes (1925, p. 115—117), the vein was said to intrude bedded biotite quartzite and mica schist. It has a quartz core and kaolinized walls. Muscovite is common in the walls, and radiating crystalline aggregates of samarskite, columbite, and monazite occur with the muscovite. In a later description of the deposit, Leonardos (1936b, p. 22—25) stated that in the radial aggregates the samarskite, monazite, and columbite have proportions of 75, 15, and 10 percent, although an earlier account (Fenner, 1928, p. 383) mentioned that columbite pre- dominates over samarskite and monazite. In any event the monazite forms exceptionally large crystals some of which weigh as much as 1.5 pounds (Leonar- dos, 1936b, p. 22—25). Djalma Guimaraes (1925, p. 118) reported that the monazite contained about 18.00 percent of T1102 and 70.67 percent of REzog. This estimate of the amount of thorium oxide, though later cited by C. D. Barbosa (1948, p. 7) and Leao (1939, p. 164), is most certainly incorrect. EX- cellent analyses for thorium oxide were made on this material by Fenner (1928, p. 386), who took special care to prepare clean, fresh samples of the monazite. Fenner made four analyses which showed 5.78, 5.68, 5.78, and 5.93 percent of ThO2 and averaged 5.79 per— cent of T1102. The monazite also contained 0.06 per- cent of U308. Leonardos (1936b, p. 22—25) wrote that the monazite from Divino de Uba contains 7 0—76 percent of RE203 and 6—8 percent of Th02 and that it has a specific gravity of 5.25. A recent analysis by Murata, Dutra, Costa, and Branco (1958, p. 7) showed 6.3 percent of Th02. Monazite-bearing weathered pegmatite dikes are found around Brejauba, Minas Gerais, at 850 José do SOUTH AME RICA Brejafiba (Guimaraes, Djalma, 1925, p. 116), and at the F azenda da Posse (Guimaraes, C. P., 1939, p. 35). At Fazenda da Posse the pegmatite consists of micro- cline and quartz plus a complex paragenetic sequence of minerals among which are muscovite, bismuthinite, beryl, garnet, columbite, magnetite, samarskite, djal- maite, tourmaline, and monazite. Monazite from the pegmatites is said to be rich in thorium oxide (Leon- ardos, 1937a, p. 9), and an analysis shows 6.7 per- cent of Th02 (Murata and others, 1958, p. 7 ). Mona- zite from a nearby pegmatite contains 13.7 percent of Th02 (Murata and others, 1958, p. 7) . Monazite taken from small stream placers in the area is reported to contain from 0 to 12 percent of T1102 (Barbosa, C. D., 1948, p. 7) . The wide range in the amount of thorium oxide in the placer monazite is unusual, and the ab- sence of thorium oxide in some samples indicates source rocks other than pegmatite in the Brejauba area. Monazite from pegmatite dikes around Ferros, including large crystals in pegmatite at Lambray de Ferros (Leonardos, 1937a, p. 9) is rich in thorium oxide. Monazite from pegmatite at Ferros, Minas Gerais, was found to have the following composition: [Analystsz Murata and Rose (in Murata and others, 1953, p. 294)] Percent Ce02 ______________________________________ 28. 78 L3403 _____________________________________ 9. 25 Nd203 _____________________________________ 15. 98 P130“ _____________________________________ 3. 83 8111203 _____________________________________ 3. 48 Gd203 _____________________________________ 1. 04 Y203 ______________________________________ . 77 Th02 ______________________________________ 7. 85 Total _______________________________ 70. 98 The original analysis was published as percentages of the total rare earths plus thorium oxide precipitate equal 102.1 percent. Here recalculated to 70.98 percent total rare earths plus thorium oxide in the monazite (H. J. Rose, Jr., written commun, 1958). Later analyses of other crystals of monazite from pegmatites at Ferros disclosed 10.0 and 8.0 percent of Th02 (Murata and others, 1958, p. 7). Large crystals of thorium oxide-rich monazite are in pegmatite dikes at Presidente Vargas (Itabira) (Leonardos, 1937a, p. 9). Scarcely abraded detrital monazite occurs with anatase, rutile, ilmenite, mag- netite, hematite, martite, tuormaline, kyanite, silliman- ite, diamonds, and gold in streams at Barao de Cocais, Minas Gerais (Hintze, 1922, p. 354). Pegmatite at Lima Duarte contains large crystals of thorium oxide—rich monazite, and, in the streams about 60 miles to the east around Sic J osé de Além Paraiba, 238—813—67—19 281 detrital monazite has been found (Leonardos, 1937a, p. 9). Monazite was identified by Hussak (1909) in con- centrates panned from a small mica-rich phenacite- bearing pegmatite vein exposed in the San Miguel de Piracicaba gold mine at Piraoicaba, Minas Gerais. Other minerals in the concentrate were amazonite, mica, black tourmaline, zircon, columbite, hematite, pyrite, :almandine, and xenotime. A pegmatite dike in muscovite schist 10 miles north- east of see Sebastiao do Rio Préto in the Conceicao district, Minas Gerais, contains abundant beryl and sparse monazite, columbite, samarskite, betafite, and bismuth minerals (Leonardos, 1936b, p. 15). Gold- bearing quartz veins at Pzassabem (Passagem) in the same area are reported to contain scarce dark—yellow crystals of monazite (Derby, 1899, p. 345; Bensusan, 1910, p. 6; Hintze, 1922, p. 355; Wichmann, 1927, p. 22—24; Gregory, 1948, p. 488). The monazite occurs in auriferous aggregates of arsenopyrite and tourma- line in the quartz veins. Monazite crystals as much as 0.1 inch in length and full of inclusions of magnetite have been found in a tungsten mine at Tripuhy near Ouro Preto, Minas Gerais (Hintze, 1922, p. 355). The deposit is in weath— ered mica schist which grades into itabirite. Appar- ently the rocks were once strongly pyritized, and the pyrite has altered to limonite. The weathered schists are covered with a thick mantle of sand in which cin- nabar, monazite, lewisite, xenotime, zircon, kyanite, tourmaline, rutile, hematite, pyrite, magnetite, gold, tripuhyite, and a titanantimonate occur (Hussak and Prior, 1897). The schists contain monazite (Derby, 1899, p. 352). The distribution and composition of monazite across a zoned pegmatite at the Emprésa Caolim mine in the Estévio Pinto district, Municipio Mar de Espanha were described by Murata, Dutra, Costa, and Branco (1958, p. 4, 9—12). They found systematic variation in distribution and composition which they interpreted to indicate fractionation of the elements during cry- stallization with enrichment of thorium in the resid- ual fluids. Crystals of monazite from the wall zones of the pegmatite contained from 6 to 7 percent of ThOZ and crystals near the quartz core contained 9.1— 12.2 percent of Th02. Average abundance of Th0? for nine samples was 7.9 percent. Monazite from the schist forming the wallrock contained 6.1 percent of ThOz. Monazite derived from the crystalline rocks is found in many of the streams in Minas Gerais. The stream deposits are shallow, and no mining industry has de- veloped on them (Gottschalk, 1915, p. 903), although 282 THE GEOLOGIC OCCURRENCE OF MONAZITE some mining has been attempted along the banks of the Rio Paraiba at the Barra sao Francisco near Sa— pucai'a, Minas Gerais, where large deposits of black sand contain a trace of monazite (Kithil, 1915, p. 14; Freyberg, 1934, p. 376). Kithil (1915, p. 13—14) likened the stream placers in Minas Gerais to those in the Carolinas, because they are in small creeks and bottomlands in a region of deeply weathered bedrock. His estimate that gravel in streams in Minas Gerais contains only 0.25—0.3 percent of monazite is nearly an order of magnitude lower than Gottschalk’s (1915, p. 903) estimate of a maximum of 2 percent of mona- zite in alluvium in 850 Paulo, but it agrees closely with earlier findings reported by Freise (1910a, p. 63). Reports by Moravia (1909, p. 39—40), and Frey- berg (1934, p. 376) showed that stream sand at the Fazenda da Arribada near Mar de Espanha contained 1 percent of monazite and 0.5 percent of xenotime in large crystals, and that especially rich sand at the Fazenda Campos Elysios, also near Mar de Espanha, contained as much as 50 percent of monazite having from 4.0 to 5.7 percent of Th02. Coarse-grained sedi- ments are richer than fine-grained sediments at Mar de Espanha, and old deposits are richer than reworked new deposits. Small stream placers commonly have local enrichments of this sort. They have received comment from many parts of the world but have failed to sustain mining except in the Carolinas. Placer monazite from streams in the interior of Brazil was thought by Kithil (1915, p. 19) to contain an average of 4.5 percent of Th02, but it seems to the writer far more likely that the average is closer to the 6.0 percent of ThOZ generally accepted for monazite in the Brazilian beach placers (Schreiter, 1922, p. 40). Obviously a wide range in the abundance of thorium oxide in detrital monazite can be cited for Minas Gerais, as, indeed, has already been done in this text. A general average would have little meaning in the economics of the stream placers. The most detailed study of monazite in stream plac- ers in Brazil was by Freise (1910a). He examined 236 placers in an area covering about 1 square degree in the drainage basins of the Rio Pomba and Rio Muriahé near the border between Minas Gerais and Espirito Santo. In the northern part of the area around the Serra do Tombas and Serra do Papageios, the bedrock is veined gneiss and schist with some in- terlayered quartzite. A few cordierite and sillimanite schists are locally present, and granite veins are com- mon. In the southern part of the area, some diorite crops out. Pegmatite dikes :at the Fazenda Santa Clara near Pomba are monazite-bearing (Catrifi, 1951, p. 289). They also contain samarskite, polycrase, and xenotime. Small crystals from these pegmatites con- tain 6.6 percent of T1102 and large crystals contain 5.3 percent (Murata and others, 1958, p. 7). The placers are in stream sediments which rest on the planed and weathered bedrock of the flat valley floors. Directly on bedrock at the base of the stream sediments is a discontinuous layer of gravel 0.2—8 feet thick. A matrix of clay and sand binds the gravel, which includes fragments of rock as much as 3 feet in diameter. About 40 percent of the placer area con- tains gravel. Ordinarily there is one layer of gravel in a deposit, and it is the source of placer monazite. At some places there are three to five beds of gravel all of which contain monazite. Overlying the gravel, or resting on bedrock where no gravel is found, is 0.4—- 7 feet of quartz sand and clay in which there are veins of limonite. From 1 to 3 feet of muck overlies the sand and clay. This overburden is lean in monazite. The placers were sampled by Freise (1910) from 1,553 pits and 1,801 boreholes. From these openings, 6,238 samples were taken. Heavy-mineral concentrates were panned from the samples, and the identity and relative abundance of the minerals associated with detrital monazite in the drainage basins of the Rio Pomba and Rio Muriahé, Minas Gerais, Brazil, were determined under the microscope. The following minerals were identified: Aeschynite Fergusonite Pyrrhotite Amphibole Fluorite Quartz (seven Andalusite Gold varieties) Anatase Hematite Rutile Apatite Hessonite Samarskite Axinite Ilmenite Sillimanite Auerbachite Kyanite Sphene Beryl Magnetite Thorite Biotite Mosandn'te Topaz Cassiterite Muscovite Tourmaline Chrysoberyl Olivine Vesuvianite Columbite Orangite Wolframite Cordierite Pleonaste Xenotime Corundum Pyrite Zircon Epidote Pyrochlore Euxenite Pyrope Of the 46 minerals found to be associated with the detrital monazite only 12 are common: quartz (seven varieties), gold, magnetite, ilmenite, rutile, tourmaline, zircon, garnet (two varieties), olivine, amphibole, biotite, and muscovite. In a sampling of 3,000 of the concentrates, the abundance of the rare-earth— and thorium-bearing minerals other than monazite, com- pared to the abundance of monazite in each sample as 100 percent, showed thorite 12 percent, xenotime 5 percent, pyrochlore 3 percent, aeschynite 0.5 percent, and orangite 0.5 percent. Characteristic mineral assemblages were found in placers formed on specific kinds of rocks. Association SOUTH AMERICA of monazite with tourmaline, amphibole, and olivine was typical in areas underlain by gneiss and diorite. Association of monazite with zircon was common in areas where granite was exposed. Association of monazite with garnet predominated in areas of gneiss. Mica, ilmenite, and gold were found in all assemblages. The size distribution of grains in samples from 0.5 short ton of monazite concentrate from the Rio Pomba area was measured by Freise (1910a, p. 53). He found that 63.4 percent of the grains were less than 0.5 mm in maximum intermediate dimension: Size (mm) Percent >2. 5 _____________________________________ 6. 3 1. 5—2. 5 _________________________________ 12. 4 . 5—1. 5 _________________________________ 17. 9 . 2— . 5 _________________________________ 26. 3 <. 2 _____________________________________ 37. 1 Total ________________________________ 100. 0 The size distribution among the particles in the con- centrate seems to reflect the sizes of the grains as they came from the parent crystalline rocks, because the grains have been transported but little from their source and are but slightly abraded. The concentrate, however, is far from monomineralic. Analyses by Freise (1910a, p. 53; 1911, p. 258) of concentrates from the Rio Muriahé and Rio Pomba show large amounts of Zr02, TiOz, SiOz, and insoluble material: Percent Rio Muriahé Rio Pomba Ce203 ______________________________ 36. 42 36. 12 (La, Nd, P0203 ______________________ 3. 94 5. 57 ZrOz _______________________________ 16. 28 _________ Th0; _______________________________ 3. 85 . 83 Fe203 _______________________________ 2. 04 1. 12 A1203 _______________________________ 1. 36 _________ TiOa _______________________________ 4. 56 _________ P205 _______________________________ 19. 65 _________ Ta305 ______________________________ . 12 _________ SiOa ________________________________ 7. 03 13. 69 Insoluble residues ____________________ 4. 75 _________ Total _________________________ 100. 00 _________ Among the 236 deposits examined by Freise, 177 placers were favorably appraised. The total area of the 177 placers was 218 million square yards of which about 81 million square yards was underlain by gravel. The gravel, however, was remarkably shallow. It was estimated to have an average thickness of 0.33 foot and a total volume of 9 million cubic yards. About 66,000 short tons of monazite was inferred to be in the gravel. Thus, the average tenor of the gravel in the 177 placers was 15 pounds of monazite per cubic yard. No record can be found of the amount of monazite shipped from the Rio Pomba district, which leads to the inference that the stream placers contributed little if anything to the total Brazilian output of monazite. 283 Detrital monazite is in sediment of the Rio Casca, a tributary to the Rio Doce near Casca, Minas Gerais, where it accompanies almandine, gold, amethyst, and scarce zircon. The heavy minerals are derived from quartzite and mica schist extensively veined by quartz. Tourmaline, garnet, pyrite, and arsenopyrite com- monly occur in the quartz (Gorceix, 1885a, p. 35—36; Smith, H. C., 1896, p. 372). An early analysis by Gorceix (1885a, p. 36), in which the thorium may not have been determined, showed 31.5 percent of P205, 36.8 percent of CeO, and 31.5 percent of DiO plus LaO in monazite from the Rio Casca placers. . The Corrego da Onca—one of many small streams by that name in Minas Gerais—near Itarana (Figueira) and tributary to the Rio Doce (Jacob, 1916) contains small amounts of detrital monazite derived from de- composed mica schist and gneiss. An analysis was made of this monazite with the following results: [Analyst: Guilherme Florence in 1908 (in Furla, 1939, p. 31)] Percent Percent (Ce, La, Nd, Pr)203_- _ _ 62. 48 Zr02 ................. 0. 40 Th02 ________________ 5. 72 CaO ................. 1. 37 P205 _________________ 28. 42 MgO ................ . 04 Sl02 ................. . 74 A1203 ________________ . 37 Total .......... 99. 87 F8203 ________________ . 33 The monazite-bearing headwaters of the Rio Mucuri (Rio Mucury) and Rio J equitinhonha between Teéfilo Otoni (Theéphilo Ottoni) and Arassuai (Arassuahy) drain strongly gneissic biotite granite cut by dikes of pegmatite (Moraes, Barbosa, and others, 1937, p. 131; Freyberg, 1934, p. 371—372; Hintze, 1922, p. 356). Coarse monazite, muscovite, tourmaline, and beryl are associated in the pegmatite with sparse xenotime, aeschynite, phenacite, and thorite. Masses of monazite which weigh as much as 2 pounds have been found in the pegmatite. An analysis of material from a peg- matite, identified as monazite but which was possibly a mixture of monazite, aeschynite, zircon, and quartz, totaled only 94.11 percent and showed 31.21 percent of 08203, 9.23 percent of Th02, 28.36 percent of P205, 10.14 percent of SiOz, 0.32 percent of A1203 4.22 per- cent of Fe203, 2.62 percent of Ti02, 5.74 percent of ZrOz, 1.16 percent of Ta205, and 1.11 percent of 03.0 (Freyberg, 1934, p. 372). Analyses of monazite con- centrates from streams in the area show less thorium oxide. Freyberg (1934, p. 376) stated that monazite concentrates of unspecified mineralogical composition from the Rio Mucuri and Ribeirao Barro Preto in the vicinity of Teéfilo Otoni contain only 4.10 per- cent of Th02. Concentrates containing 90 percent of monazite, made from sand in the Cérrego das Amer- icanas near Teéfilo Otoni, were said by Moraes, Bar- bosa, Arrojado Lisb6a, and Lacourt (1937, p. 131) 284 to have 6 percent of ThOZ. This analysis suggests that detrital monazite from the region contains about 6.7 percent of Th02. The abundance of monazite in the streams around Teéfilo Otoni varies locally from 5 percent of the sand, in the vicinity of the town, to 1.5 percent of the sand, near the junction of the Rio Mutum with the Rio Mucuri, and in the Cérrego das Americanas, Corrego da Onca, and Cérrego do Surucucfi, and generally 1 percent of the sand, in the Rio Mucuri (Moraes, Bar- bosa, and others, 1937, p. 131—132; Hintze, 1922, p. 356). Other heavy minerals in the sands include magnetite, topaz, garnet, tourmaline, cassiterite, chry- soberyl, rutile, and ilmenite. Monazite is most abun- dant in the streams that have the least amount of magnetite, ilmenite, and rutile. Gneiss and pegmatite are exposed in the basin of the Corrego do Sobrado about 2 miles south of Rio do Peixe in the Municipio de Passa Tempo, Minas Gerais. Alluvial and eluvial deposits in the basin contain round grains of monazite. A concentrate panned from alluvium was reported by Peixoto and Guimaraes (1953, p. 13) to consist of the following: Percent Quartz ____________________________________ 26. 0 Monazite __________________________________ 14. 8 Zircon _____________________________________ 2. 2 Ilmenite ___________________________________ 1 1. 8 Magnetite _________________________________ 44. 9 Sillimanite _________________________________ . 3 Total ________________________________ 100. 0 An analysis of the monazite was made by Peixoto and disclosed that it contained 10.17 percent of Th02: [Analyst Peixoto (in Peixoto and Guimarfios, 1953, p. 32)] Percent Percent Ce203 (group) ________ 39. 93 Ti02 ________________ 0. 59 La203 _______________ 16. 08 03.0 ________________ . 12 Y203 (group) ________ . 88 MgO _______________ . 06 ThOz _______________ 10. 17 MnO _______________ Trace U303 ________________ None PbO ________________ . 79 P205 ________________ 24. 25 ZrOz ________________ Trace SiOz ________________ 2. 24 H20 ________________ . 80 A1203 _______________ 1. 06 ~—-—— FeO ________________ 3. 26 Total _________ 100. 23 Esriarro SANTO The monazite in crystalline rocks in the State of Espirito Santo has received but little mention in the literature. It is far overshadowed by discussions of monazite in the famous beach placers. A few localities, however, have been described. Monazite-bearing gneis- sic biotite granite crops out in the highlands that form the border with Minas Gerais. Monazite has been found from the area between the Rio Mutum in Minas Gerais and the Rio Pancas in Espirito Santo to the THE GEOLOGIC OCCURRENCE OF MONAZITE junction of the Rio 85.0 J 0910 with the Rio Doce. The granite gneiss around the Rio 850 J 05.0 has augen of garnets and rutile and is cut by pegmatite dikes. Large masses of monazite in the pegmatite dikes display many fine cleavage cracks filled with xenotime, aeschy- nite, and phenacite (Hintze, 1922, p. 356). The Serra dos Aimorés and Serra da Liberdade on the border between Espirito Santo and Minas Gerais, underlain by monazite-bearing gneisses and pegmatite dikes, constitute about half of the upper drainage basin of the Rio 85.0 José (Erichsen, 1948, p. 77; Frey- berg, 1934, p. 371). This stream is the principal source of Lagoa J uparana, Espirito Santo, which has appreci- able amounts of monazite and ilmenite along its shores (Erichsen, 1948, p. 77). An impure monazite con- centrate from a pegmatite vein exposed in the south- ern part of the Serra dos Aimorés contains 9.23 per- cent of Th02 (Freise, 1911, p. 258). Between 65 and 70 percent of the concentrate appears to have been monazite; therefore, the monazite may have as much as 14 percent of ThOz. A coarsely crystalline aggregate of magnetite and ilmenite from a mica syenite at the Fazenda Catita on the lower Rio Doce, Espirito Santo, contained mona- zite, zircon, corundum, and biotite (Derby, 1902, p. 211). The monazite occurs as isolated crystals in the iron oxides and biotite. At Guarapari, pegmatite dikes intrude amphibolite and biotite gneiss. The dikes contain accessory gar- net, ilmenite, monazite, and zircon (Moraes and others, 1937, p. 547; Nova, 1945, p. 282). BAHIA The State of Bahia, also, is rarely cited for monazite- bearing crystalline rocks, although the famous coastal placers are often mentioned. Grains of monazite have been observed (Leonardos, 1937a, p. 9) in a sequence of mesozonally metamor- phosed diamondiferous tillite, sandstone, and conglom- erate at Salobro and Lencéis (Lencoes). Monazite was originally deposited as detrital grains with the sediments, which are a part of the Lavras series of quartzite and conglomerate of Cambrian age (Oliveria, A. I. de, 1956, p. 19—20). After metamorphism, uplift, and exposure, the series was deeply weathered and eroded. This weathering and erosion released diamonds from the rocks, and placer deposits formed. Monazite is found in the placers. The monazite consists of practically unabraded crystal fra g- ments, some of whose surfaces are encrusted with prisms of zircon (Hintze, 1922, .p. 350). Apparently unabraded crystal fragments of monazite seem so unlikely to be recycled detrital grains that SOUTH AME RICA some workers have attributed the monazite to a source in granite, gneiss, and pegmatite exposed between Sal- obro and Canavieiras, and in the Serra do Mar (Gor- ceix, 1884b). Hintze (1922, p. 350) summarized com- ments by Henri Gorceix—that is, if the crystal frag- ments of monazite came from granite instead of quartz- ite, then the monazite should be accompanied by heavy minerals common in the areas underlain by granite and gneiss. Chrysoberyl, spodumene, andalusite, and beryl are found in streams draining the granite and gneiss, but they are absent from the diamond placers at Salébro. Thus, the heavy minerals indicate that the monazite came from the Lavras series. Inasmuch as the fragments of monazite have little or no detrital rounding, they may have been recrystallized when the Lavras series was metamorphosed, or have been etched and overgrown, as observed elsewhere by Derby (1900b, p. 218~219), when the Lavras series was weathered. Vugs and druses lined with monazite, quartz, mag- nesite, and other minerals are exposed in magnesian marble at Catita Grande do Piraja in the vicinity of Bom J esfis dos Meiras, Bahia (Uhlig, 1915). Pneuma- tolytic action of pegmatitic fluids on the marble was said by Leonardos (1937a, p. 16) to have formed the druses. Pegmatite dikes in the area consist of coarse- grained quartz and albite accompanied by beryl, topaz, spodumene, lithium mica, manganese garnet, tourma- line, xenotime, and monazite. Minerals in the druses include monazite, xenotime, magnesite, dolomite, ru- tile, sphene, tourmaline, hematite, and topaz. The monazite deposited in the druses is notable for its lack of thorium oxide. An average of two analyses made by Uhlig (1915, p. 41) showed that the monazite, spe- cific gravity 5.162, contained only 0.05 percent of ThOZ: [Analyst: Uhlig (1915)] Percent Percent Ce203 _______________ 26. 06 MgO _______________ Trace (La, Nd, P1920; ______ 39. 92 MnO _______________ Trace Y203 ________________ 2. 78 H20 ________________ 0. 54 Th02 _______________ . 05 Insoluble residue _____ . 40 P205 ________________ 29. 34 —-—- Fe203 _______________ Trace Total _________ 99. 50 CaO ________________ . 41 In its low amount of thorium oxide this monazite resembles monazite from low-temperature deposits, carbonatites, and marble elsewhere in the world. Other localities to which the monazite-bearing peg- matite dikes and marble in the vicinity of Bom J esfis dos Meiras have been referred are the Serra das Eguas (Leonardos, 1937a, p. 9, 15), the southern spurs of the Serra do Espinhago, and the upstream part of the Rio de Contas (Hintze, 1922, p. 352). 285 Thorium-rich monazite from Morro da Gloria, Itam- bé, Bahia has been analyzed to show the effects of pro- gressive weathering on the composition of the mona- zite. The fairly stable water content may indicate that all the samples were only slightly weathered. Chemical analyses, in percent, of monazite from M orro da Gloria (Analyst: Peixoto (in Peixoto and Guimaraes, 1953, p. 21] Fresh Slightly Weathered Weathered 06203 ____________________ 32. 60 ____________________ LazOs ____________________ 28. 77 ____________________ 2 a _____________________ . 98 ____________________ Th02 ____________________ 8. 88 8. 82 6. 54 U308 _____________________ . 07 Trace Trace 8.285 --------------------- 2?. g3 -------------------- l 2 _____________________ . ____________________ A1203 ____________________ . 88 89 1. 19 F8203 ____________________ . 48 ____________________ T102 _____________________ Trace ____________________ CaO _____________________ . 02 ____________________ e38 ————————————————————— a ———————————————————— n ________________________________________ PbO _____________________ . 16 16 11 H20 _____________________ 58 27 52 Total ______________ 100. 22 ____________________ Red syenite from the Serra do Stauba, Bahia, con- tains accessory monazite (Derby, 1889, p. 113). Mona- zite occurs in gneiss at Estrada de Ferro de Nazareth in the Vicinity of Ubaira (Areia), Bahia (Leonardos, 1937a, p. 15), and sandstones of Tertiary age along the coast of Bahia and Espirito Santo contain detrital monazite (Leonardos, 1937a, p. 9). Detrital monazite, as has already been mentioned, is in the diamond placers in the tributaries to the Rio Pardo in the vicinity of the village of Salfibro. Specific localities mentioned by Gorceix (1884b; 1885a, p. 30), Oliveira (1902, p. 19—20), and Derby (1905, p. 165) include the Riacho Salobrinho, the Rio Salébro, the Cérrego do Rico, the Cérrego do Desengano, and the Corrego do 850 J osé. Detrital monazite is also found in the lower Rio Pardo at Jacaranda (Oliveira, F. de P., 1902, p. 19—20). Diamond placers at Bandeira de Mello on the Rio Paraguacu (Rio Paraguassu) are exceptionally rich in monazite compared to other diamond placers in Bahia (Hussak, 1899, p. 3474351; Hussak and Reiting- er, 1903, p. 550—551; Hintze, 1922, p. 351; Leonardos, 1937a, p. 15). Accompanying the monazite and dia- monds are detrital quartz, orthoclase, muscovite, biotite, chlorite, spinel, corundum, sillimanite, hercynite, xeno- time, garnet, zircon, epidote, actinolite, chrysoberyl, diaspore, kyanite, rutile, ilmenite, hematite, magnetite, black tourmaline, and native gold. In addition to the usual quartz, the gravel in the stream contains some 286 fine-grained garnetiferous biotite granite, amphibolite, chlorite gneiss and schist, sillimanite-bearing muscov- ite schist, and very rare fragments of coarse-grained sandstone. Pegmatitic granite is exposed in the valley of the Rio Paraguacu not far upstream from the placers. Evidently the detrital minerals came from granitic rocks, gneiss, schist, and sandstone. Monazite from the placers contains tiny leaves of a muscovitelike mineral as rare inclusions and has ran— domly arranged fluid inclusions. It is very rich in thorium oxide and has a specific gravity of 5.012. An average of five analyses of monazite from Bandeira de Mello gave the following results: [Analyst: Reltlnger (in Hussak and Reitinger, 1903, p. 559)] Percent Percent 08203 _______________ 32. 14 F6203 ............... 1. 79 (La, 1%)an __________ 10. 61 ZI’Oz ________________ . 60 Nd203 ______________ 15. 38 08.0 ________________ . 20 Th0; _______________ 10. 05 H20 ________________ . 92 P205 ________________ 25. 51 ~——-——— Si02 ________________ 2. 63 Total _________ 100. 67 A1203 _______________ . 84 A later analysis of monazite from this locality, made by Guilherme Florence in 1908 (Furia, 1939, p. 31), showed only 3.76 percent of Th02. No evident reason for the difference between the analyses appears in the discrip— tion of the material analyzed. Indeed, it seems to the writer very unlikely that such dissimilar monazite could be collected from the same placer unless the monazite was virtually in place and the geologic provenance was wholly different for the two samples. Until more is known about the composition of monazite from Bandeira de Mello, the five analyses by Hussak and Reitinger must be accepted as the more convincing. The monazite from Bandeira de Mello thus seems to contain ten times as much thorium as monazite from the Riacho Varas in the 8210 Joao da Chapada part of the Diamantina diamond district in Minas Gerais. Thorium—poor monazite at the Riacho Varas seems to be derived from sericite phyllite, whereas the thorium— rich monazite at Bandeira de Mello probably comes from garnetiferous biotite granite and pegmatitic granite. PARAfBA AND RIO GRANDE D0 NORTE Monazite is one of the 84 different minerals identified in the Borborema pegmatite district in northeastern Brazil (Rolfl’, 1946, p. 26—27), but no analyses of the monazite have been published. The district straddles the boundary between the States of Paraiba and Rio Grande do Norte (Moraes, 1956, fig. 3). It has been exploited as a source for beryl and for niobium and tantalum minerals, but no monazite has been produced. Accessory monazite occurs in pegmatite dikes in the vicinity of Sabugui (Santa Luiza) and Picui, Paraiba, THE GEOLOGIC OCCURRENCE OF MONAZITE and at Capoeiras near Santa Cruz in Rio Grande do Norte (Johnston, 1945, p. 40). Detrital monazite has been found in eluvial and alluvial placers in the basins of the Rio Serido and Rio Acu (Rio Assu) (Rolfl’, 1955) around 850 Rafael, F lorana, Acari, and Currais Novos in the State of Rio Grande do Norte and at Picui in Paraiba (Moraes, 1956, p. 137). Murata, Dutra, Costa, and Branco (1958, p. 7) reported that monazite from plagioclase pegmatite at the Orquima mine in Municipio Sao Rafael in Rio Grande do Norte contains 8.4 percent of Th02. About 6 miles to the southwest of the mine, small crystals of monazite from a granite stock were found by Murata, Dutra, and coworkers to have 8.1 percent of Th02, and a large crystal of monazite from pegmatite at 850 Bento mine in Municipio Sao Bento, Rio Grande do Norte, was shown to contain 2.6 percent of Th02. Analyses of monazite collected from a pegmatite dike at Santa Cruz, Rio Grande do Norte, by W. D. Johnston, J r., are given. Chemical analyses, in percent, of monazite from Santa Cruz [Analystz Marble (1949b, p. 71] Fresh Slightly Heavily weathered weathered RE203 ___________________ 68. 40 44. 14 40. 45 T O .41 .95 1 05 O 27.28 20.69 43 38 . 35 ____________________ 1.33 26.45 1 00 2.49 2.68 4 32 . 03 ____________________ .00 4 10 6 64 00 .93 2 96 100. 29 99. 94 99.80 In these analyses the percentage of thorium oxide in- creases as the degree of weathering increases. The analyses of fresh, slightly weathered, and weathered monazite shown from Morro da Gloria indicate a de- crease in thorium oxide with increase in degree of weathering. Possibly something is wrong with one set of data. GOIAS AND MATO GROSSO Monazite associated with thorite, orangite, fergu- sonite, gummite, and uraninite has been reported from the diamond—mining districts in the State of Goias (Leonardos, 1937a, p. 9; Hintze, 1922, p. 350; Truchot, 1898, p. 146). Although the nature of the occurrence is not described, the mineral association indicates peg— matites as the source. Fluvial deposits near Catalao, Goias, are monazite bearing. A concentrate from this locality contained about 5.92 percent of Th02 but apparently had little SOUTH AME RICA more than 60 percent of monazite, to judge from an incomplete analysis given by Freise (1911, p. 258). Crystalline rocks are probably the source of the euhed- ral monazite reported from the diamond- and gold- bearing streams in the State of Mato Grosso (Hussak, 1891, p. 471—472; Hintze, 1922, p. 353). BEACH PLACERS Beach placer deposits of monazite are known but apparently are unexploited as far south in Brazil as the Ilha de Sac Sebastiao on the coast of 85.0 Paulo (Engenharia, Mineracao e Metalurgia, 1956). The mined coastal deposits extend northward intermittent- ly from Rio de J aneiro through Espirito Santo to Canavieiras in Bahia (Brazilian Eng. and Mining Rev., 1905, p. 153; Miranda, 1943, 196—197; Lafer, 1950, p. 156; Leonardos, 1950, p. 137; Gillson, 1950, p. 686, Floréncio, 1952, p. 44; Strod, 1953, p. 123). The pla- cers occur in modern beaches, old elevated beaches and bars, dunes, and in the banks and bars of streams emptying at the coast (Mertie, 1949, p. 632). The occurrence of the beach placers in certain places is re- lated to the distribution of sandstone of Cretaceous and Tertiary age. Where the lower beds of the sand- stone (Gillson, 1950, p. 686) crop out at the shore and are disintegrated by ocean waves, monazite and ilmen- ite are released to be sorted and deposited on the beaches. The Cretaceous and Tertiary sandstones are nowhere rich enough in monazite to be mined. Monazite reworked from the coastal sandstone pro— vides a more abundant supply for the present beaches than monazite discharged by streams. Beaches near bluffs supported by monazite-bearing sedimentary rocks are richer in monazite than beaches at the foot of granitic or gneissic cliffs or beaches at the mouths of streams. Old raised beaches inland from the coast and much modified by erosion may be rich sources for monazite. Natural concentrations of monazite at the surface along some storm beaches (marinhas) have occasionally reached 90 percent of the volume of the sand in the upper few inches of the beach, which per- mitted producers to skim the monazite from the beach and sell it without further treatment. Monazite ordinarily makes up but a few percent to 7 or 8 percent of the total volume of the sand, and it has to be separated from the sand before it can be sold, but the variety of accessory minerals is less than in coastal deposits in the United States (Gillson, 1950, p. 692). Commercial monazite concentrates from Bra- zil contain 86 to 98 percent of monazite and average about 92 percent (Freyberg, 1934, p. 379). Between 1900 and 1947 Brazil exported 62,115 short tons of monazite concentrate of which 38,800 tons came from 287 Espirito Santo and 23,315 tons came from Bahia and Rio de J aneiro (Brazilian Eng. and Mining Rev., 1905, p. 153; Gottschalk, 1915; Kithil, 1915, p. 13; Freyberg, 1934, p. 376—378; Erichsen, 1948, p. 76; Catrifi, 1951; Mining J our., 1942). The sizes of the deposits are poorly discussed in the literature, though they are commonly stated to be indi- vidually smaller than the Indian placers. Evidently small, relatively rich deposits from which a few score tons to several hundred tons of monazite could be ex- tracted annually attracted most attention until large monazite-bearing ilmenite placers were opened about 1927. Reserves of monazite in the beach deposits, like the sizes of the individual placers, have received little com- ment in the literature. Kithil (1915, p. 19) admitted that estimates of the amount of monazite in the beach placers were diflicult to make, but it seemed likely to him that the placers could yield a total of at least 15,— 000—20,000 tons of monazite. In the following 35 years 17,146 tons of monazite was produced from the beaches, and recent estimates considerably enlarged the reserves. Leonardos (1950, p. 137) estimated there was at least 100,000—150,000 tons of monazite along the coasts of Rio de J anerio, Espiritc Santo, and Bahia. Two plants capable of processing 1,500—2,000 tons of monazite per year were being operated in 1953 at Vitéria and S50 Paulo (Strod, 1953, p. 123). RIO DE JANEIRO Monazite placers along the coast of Rio de J aneiro are said to be small (Catrii’i, 1951, p. 289). Monazite is common in the beach sand at the city of Rio de J aneiro (Derby, 1889, p. 110), but some 75 miles along the coast to the east of that city, at the Praia Massan- duba at Cabo Frio only small amounts of monazite occur in the coastal ilmenite placers (Gottschalk, 1915, p. 903) . To the northeast, small beach placers are known at Barra de S50 J 050, Macaé, Retiro, Buena, Samambaia, and Ponta da Barrinha, the last being in the Munici‘pio of 850 J oac da Barra near the mouth of the Rio Paraiba (Gottschalk, 1915, p. 903; Frey- berg, 1934, p. 376; Abreu, 1937, p. 450; Miranda, 1943, p. 197). Sand bars and banks in the lower reaches and at the mouth of the Rio Paraiba are monazite bearing, and they may include some of the best placers in the State (Barbosa, 1909; Catrifi, 1951, p. 290; New Zealand Mines Rec, 1905; Moraes, 1937 , p. 67). The average amount of thorium oxide in monazite from beach placers along the coast of the State of Rio de J aneiro has been reported as 5.87 percent by Leao (1939, p. 164), which probably refers to the analysis made by T. H. Lee in 1917 (Leonardos, 1937b, p. 559). 288 Esrimro SANTO Monazite was found in the coastal sand of the State of Espirito Santo in 1895 (Freise, 1910b, p. 471), and the first monazite mine was opened at Guarapari in 1898 (Borges, 1937, p. 66). An initial production of 660 short tons was exported in 1900 (Erichsen, 1948, p. 73; Frayha, 1947, p. 71—76). Shortly thereafter placers were opened elsewhere along the coast from Barra de Itabapoana in the south to Sic Mateus in the north (Mining J our., 1903c). At least one placer, that in the vicinity of Ponta do Siri, was worked almost continuously until 1924. Loss of markets due to the production of monazite from India rather than depletion of the deposits brought closure. Mining of the beach placers in Espirito Santo was resumed in 1927 with monazite a byproduct of the recovery of ilmenite. Reserves of monazite along the beaches of Espirito Santo have been collectively placed at more than 50,- 000 tons (Catriu, 1951, p. 290), and sums of the reserves for individual beach deposits in the State were estimated as about 15,000 short tons by Frayha (1947 , p. 80—86) or about 150,000 short tons by Miranda (1943, p. 196—197). The most numerous and most important ilmenite— monazite placers in Espirito Santo lie between Barra de Itabapoana and Guarapari (Moraes, 1937, p. 69; Erichsen, 1948, p. 77). With a few exceptions these deposits are elevated bars which form narrow ridges, a few hundred feet to 1.5 miles long covered by a thick- ness of 1—2 feet of low-grade or barren sand (Gillson, 1950, p. 689—690). Although the grade of the sand varies widely among the deposits, Gillson (1950, p. 690) estimated that the average for the elevated bars is 32 percent of heavy minerals of which about 55 per- cent is ilmenite, 5 percent is rutile, 25 percent is zir- con, and 5+ percent is monazite; the balance consists mainly of tourmaline, staurolite, sillimanite, kyanite, and corundum. At Barra de Itabapoana, spinel is plentiful, but it is scarce or absent elsewhere. The deposit at Ponta do Siri (Bfia Vista de Siri, Siri, Siry, Ciri) is an isolated bar, some parts of which contain as much as 45 percent of monazite, but the total ton- nage is not large (Gottschalk, 1915, p. 903; Freyberg, 1934, p. 377; Gillson, 1950, p. 690). About 2 miles north of Ponta do Siri at Maratayso Praia, the tenor drops to 7 percent of monazite, and the main monazite- bearing layer of sand is about 3,300 feet long, 20 feet wide, and 0.2 foot thick (Freyberg, 1934, p. 377). Placers at Maratayso Praia are said to be mined out (Hintze, 1922, p. 356). Undescribed placers at Jacunem (Jucunem) have yielded monazite that contains 5.70 percent of Th0; THE GEOLOGIC OCCURRENCE OF MONAZITE (Leonardos, 1937b, p. 559; Leao, 1939, p. 163). Mona- zite from the coast of Espirito Santo has also been reported to have 6.75 percent, 6.00 percent (Leonardos, 1937b, p. 559), and 6.06 percent of ThOz, but the exact location of the material analyzed was not specified (Imp. Inst. [London], 1914a, p. 60): Percent Ce203 (group) ______________________________ 62. 12 Yao. (group) _______________________________ . 80 T1102 ______________________________________ 6. 06 P305 ______________________________________ 28. 50 SiOg _______________________________________ . 75 A1203 ______________________________________ . 10 F8203 ______________________________________ . 97 CaO ______________________________________ . 21 Loss on ignition ____________________________ . 38 Large stream placers in the lower Rio Itabapoana are mentioned but not discussed by Catrii’i (1951, p. 289). About 20 localities in the Vicinity of Itapemirim, from Béa Vista in the south to Meaipe in the north, have been mentioned as monazite deposits. They are mainly elevated bars of small size (Gillson, 1950, p. 690). Ilmenite and monazite placers at Béa Vista were mined for monazite from 1909 to 1913 and in 1948 were estimated to contain 7,560 short tons of ilmenite and 127 short tons of monazite (Frayha, 1947, p. 83; Erichsen, 1948, p. 74—75, 83). The deposit at Meaipe was said to contain about 20,000 tons of heavy min- erals, which included 55 percent of monazite (Miran- da, 1943, p. 196) ; this deposit was at one time reputed to be the richest monazite placer in Brazil (Grottschalk, 1915, p. 904). In another estimate the reserves at Meaipe were given as 3,300 short tons of monazite (Freyberg, 1934, p. 377 ). Placers at Itapemirim, Pi- tas, Mangue, Sacco, Cacurucagem, Quartéis, Tiriricas, and Béa Vista were said by Freyberg (1934, p. 377) to average 41 percent of monazite in the raw sand and to contain as much as 70.5 percent of monazite. This estimate of the relative abundance of monazite evi- dently refers to selected layers, because the estimate by Frayha of the reserves at B63. Vista shows ilmenite 60 times more abundant than monazite. Usually beach placers and elevated bars have mona- zite that varies only slightly from place to place in the amount of thorium oxide it contains, but the placers around Itapemirim seem to be an exception. They have been the sources of monazite that has a wide range in thorium oxide content. Analyses by T. H. Lee and L. C. Ferraz of monazite from Itapemirim, Itapicfi, and Curfi were reported to show 5.20, 7.09, and 11.50 percent of ThOZ (Leonardos, 1937b, p. 559, Leao, 1939, p. 163), and monazite from Meaipe was said to contain 6.31 percent of ThOz (Miranda, 1943, p. 196). SOUTH AME RICA In the vicinity of Anchieta, particularly about Parati, Imbiri, Pipa de Vinho, and the shore near the lake at Maeba, various small placers, mainly elevated bars except Maeba which is a modern beach placer, were mined for many years (Erichsen, 1948, p. 73-75; Gillson, 1950, p. 690). The deposit at Parati was thought by Frayha (1947, p. 87) to have good possi- bilities for monazite and was estimated by Erichsen (1948, p. 87) to have a reserve of 3,900 short tons of monazite. At Maeba the reserves of monazite have been variously estimated as 1,500 short tons (Freyberg, 1934, p. 377) or at most 3,900 short tons (Frayha, 1947, p. 86; Erichsen, 1948, p. 75). The deposit was also said to contain 165,000 short tons of crude sand of unspecified tenor, from which concentrates containing 60 percent of monazite and 40 percent of ilmenite could be taken (Miranda, 1943, p. 196). Although the richest layers in these deposits may contain as much as 35 percent of monazite in the crude sand, they may be buried by barren overburden as much as 10 feet thick. Anchieta monazite as analyzed by L. C. Ferraz con- tained 5.20 percent of Th02 (Leonardos, 1937b, p. 559). One of the main centers of mining between Itape— mirim and Meaipe were placers at a locality known as Joana near Muquicaba where ilmenite and monazite were produced between 1926 and 1941 (Frayha, 1947, p. 84; Erichsen, 1948, p. 75). No estimates of reserves in this deposit have been given. A small placer in an elevated bar at Uba (Ubfi, Ubu), whose richest layers have 35 percent of monazite, was reported by Freyberg (1934, p. 377) to contain 310 short tons of monazite. The area was thought by Frayha (1947 , p. 86) to be worth further exploration despite an earlier account that described the deposit as worked out (Hintze, 1922, p. 356). Monazite from the placer at Maeba contains an average of 6.5 percent of Th02 (Miranda, 1943, p. 196). Monazite from a placer between Maeba and Meaipe had the following percentage of thorium oxide: [Analystz D. B. Borges (in Rocha, 1939, p. 19)] Percent 06203 _____________________________________ 30. 0 Laan (group) ______________________________ 30. 07 ThOz ______________________________________ 6. 31 About 4 miles north of Meaipe is the southernmost of the monazite-bearing beaches of the Guarapari re— gion. Placers around Guarapari, including deposits at Praia do Vaz, Vila Velha, Rastinga, Canto do Riacho and Praia de Diogo, have been mined for both ilmen- ite and monazite since 1926 (Freyberg, 1934, p. 378; Miranda, 1943, p. 196; Frayha, 1947, p. 84; Erichsen, 1948, p. 75). One report implied that the placers around Guarapari contain only 0.4 percent of heavy minerals (Rocha, 1939, p. 18), however, this content 238—813—67—20 289 probably refers to the average beach sand, because the local mining history shows that a much better grade of sand has been found, and Frayha (1947, p. 84) and Erichsen (1948, p. 85) noted that the placer at Canto do Riacho is one of the richest in Espirito Santo and has reserves estimated at 5,500—6,600 short tons of monazite. Miranda (1943, p. 196) seemingly indicated a reserve 15—20 times this great for the Guarapari region. Monazite from Vila Velha was analyzed in 1933 by A. Girotto and reported (Leonardos, 1937b, p. 559) to have from 5.47 to 6.16 percent of ThOZ. The same reference reported the monazite from Guarapari to have 6.31 percent of Th02. Monazite from Praia de Diogo and Canto do Riacho contains 6.21 percent of Th02 (Miranda, 1943, p. 196). The placer 15 miles north of Guarapari at Ponta da Fructa is mineralogically very different from other placers in southern Brazil. It is rich in zircon, garnet, and andalusite; the ilmenite is rich in Ti02, and the monazite only appears in the lower layers of the placer (Erichsen, 1948, p. 81; Gillson, 1950, p. 690). The deposit is variously estimated to have reserves of 220 short tons of monazite (Freyberg, 1934, p. 378) or 2,200 short tons of monazite and 67,000 short tons of ilmenite (Frayha, 1947, p. 80—81; Erichsen, 1948, p. 81). Beaches near the mouth of a stream at Pifima in the Municipio de Iconha are the sites of the Caju and Patrimonio deposits. Though they were at one time said to have been worked out as a source of monazite (Hintze, 1922, p. 356), they were explored for ilmenite in 1928—30 and in 1929 supplied 4,961 short tons of monazite—bearing ilmenite concentrate to Germany (Frayha, 1947, p. 87). The concentrate consisted of (Rocha, 1939, p. 19) the following minerals: Percent Ilmenite __________________________________ 71. 61 Monazite _________________________________ 6. 00 Zircon ____________________________________ 13. 00 Quartz ____________________________________ 5. 97 Magnetite ________________________________ . 22 Other minerals _____________________________ 3. 20 Total _______________________________ 100. 00 After 1929 various and conflicting estimates of the reserves of the Caju and Patrimonio deposits have been presented. Freyberg (1934, p. 377) was of the opinion that they contained 20 or 30 tons of monazite. The Caju deposit was estimated by Miranda (1943, p. 197) to contain 312,000 cubic yards of heavy sand con- sisting of 60—70 percent of ilmenite and 10—12 percent of monazite, the remaining percentage being dominated by zircon. An unnamed deposit at Pifima was said by 290 Miranda (1943, p. 197) to contain 55,000 short tons of crude sand having 5 percent of monazite. Monazite in the Pifima area contains 6.2 percent of Th0, (Rocha, 1939, p. 19). Beach sands along the shore of the bay at Vitéria con— tain monazite (Hintze, 1922, p. 356). Along the beach 10—12 miles north of Vitoria the placer at Carapebfis contains about 0.5 percent of monazite in the raw sand (Miranda, 1943, p. 197) and has reserves of monazite estimated to be 2,000 short tons (Frayha, 1947, p. 82; Erichsen, 1948, p. 82). The deposit at Carapebfis was worked about 1910—12, and though past production is reputed to have been large, it has not been recorded (Gillson, 1950, p. 691; Frayha, 1947, p. 82). The Serra, Capuba, and Jacaraipe deposits occur north of Vitéria. Capuba and Jacaraipe are con— tiguous in a long, narrow bar (Gillson, 1950, p. 691). The deposit at Jacaraipe is said to contain 134 short tons of monazite and 9,750 short tons of ilmenite (Frayha, 1947, p. 82—83; Erichsen, 1948, p. 83). A small placer occurs along the beach north of Vitéria at Nova Almeida (Freyberg, 1934, p. 378). This placer is probably the same as the small placer referred to Béa Vista de Nova Almeida by Gillson (1950, p. 691). Twenty miles to the north of Nova Almeida par— ticularly large monazite placers were said by Gottsch- alk (1915, p. 903) to have formed at the mouth of the Rio Doce at Regencia, but no particular information was given. Freyberg (1934, p. 378) mentioned that at Regencia 1—2 percent of monazite occurs with ilmen— ite and magnetite, but again the size of the deposit was not described. Gillson (1950, p. 691) observed many concentrations of titaniferous magnetite accompanied by garnet and some ilmenite in the delta of the Rio Doce, but monazite was not mentioned. The most northerly of the monazite placers on the coast of Espirito Santo are between the mouth of the Rio 8130 Mateus at $5.0 Mateus and the State boundary. These placers are of undetermined size and tenor but are thought to contain at least 550 tons of monazite (Freyberg, 1934, p. 378). BAHIA The coast of the State of Bahia, site of the first monazite mines in Brazil, is spotted with placers from the mouth of the Rio Mucuri (Rio Mucury) north- ward to Canavieiras. Locally the beach sands are yellow because of the abundant monazite (Gorceix, 1885a, p. 31; Leonardos, 1937a, p. 3), gray with brilli- ant black particles of magnetite and ilmenite, or red from fragments of garnet (Leao, 1939, p. 163). In places the sand is solidified but can be broken up with THE GEOLOGIC OCCURRENCE OF MONAZITE picks and hoes. An average of 10 analyses of mona- zite sand, presumably concentrates of difierent degrees of purity, from the coast of Bahia shows 3.33 percent of Th02 (Leao, 1939, p. 163). In the vicinity of the town of Mucuri (Mucury), especially at the mouth of the Rio Mucuri, at Porto Alegre, the Riacho das Ostras, and Barra Nova, there are said to be notable monazite placers, but no details have been given. Monazite concentrates from Mucuri contain 1.5—5.0 percent of Th0, (Leonardos, 1937a, p. 14), and the monazite itself has 5—6 percent of ThOZ (Leao, 1939, p. 163). According to Leonardos (1937a, p. 13—14), monazite placers extend contin- uously northward along the coast from Mucuri through Maroba (Vicosa) and Caravelas to Alcobaca. The tenor of the placers decreases northward to a low of 2.5 percent of monazite in the sand at Alcobaca (Leonardos, 1937a, p. 13—14). Values of the higher tenors in the south are not given by Leonardos, but locally they must be very high because at Caravelas there is enough monazite in the sand to give it a yellow cast (Gorceix, 1885a, p. 31). Besides monazite the placers around Caravelas contain zircon and sphene (Hintze, 1922, p. 351). Two old analyses of monazite concentrates from Caravelas made in 1885 by Gorceix (1885b, p. 34; Leonardos, 1937a, p. 13; Lisboa, 1950, p. 28) have high values for the rare earths; however, thorium was not determined independently but is included in the rare earths : Percent A B 0e20, _______ ' _____________________________ 2s. 0 31. 3 (La, Nd, Pr)203 ___________________________ 35. 8 39. 9 mo. ______________________________________ 25. 7 28. 7 s102 ______________________________________ 3. 4 _______ ZrO; ______________________________________ 6. 3 _______ CaO _____________________________________ 1. 1 _______ Total _______________________________ 100. 3 99. 9 A. Specific gravity, 5.1. Monazite from nearby placers like those at Alcobaca contains the following percentage of thorium oxide (Johnstone, 1914, p. 58; Imp. Inst. [London], 1914a, p. 60): Percent Percent (Ce, La, Nd, Pr)203__ 61. 40 F6203 _______________ 1. 50 Y203 ________________ . 70 CaO ________________ . 30 ThOz _______________ 6. 50 Loss on ignition ______ . 64 P205 ________________ 28. 46 —————- SiOz ________________ . 64 Total _________ 100. 22 A1203 _______________ . 08 Monazite from the placers at Mucuri contains 5—6 percent of ThOz according to analyses by L. C. F erraz and 1.2—5.8 percent of ThOZ as determined by Souza Carneiro (Leonardos, 1937b, p. 559). The latter SOUTH AMERICA determinations probably made on impure concentrates. The Prado area, mentioned earlier as the site of the first worked placers in Bahia (Smith, 1896, p. 372; Mining Jour., 1903b; Leonardos, 1937 a, p. 3) includes deposits extending intermittently southward to Alco- baca and northward to Cumururatiba (Curumuchati- ba), Cai (Foz do Cally). Placers at Cai were mined in 1905 (Leonardos, 1937a, p. 12). Monazite-bearing beaches have been reported at Barreira, Itapara, Dois Irmaos, Cérrego do Ouro (Rio do Ouro), Rio do Peixe, Ponta do Paixao, and Ponta da Barreira. The most important deposits are north of Prado at Com- oxatiba, also known as Gordonia, where the placers along the storm beach are about 2 miles long, are 3—7 feet thick, and contain as much as 70 percent of mona- zite (Gillson, 1950, p. 692; Leonardos, 1937a, p. 13). The deposit was worked about 1903 by John Gordon. Accompanying the monazite are quartz, xenotime, spi- nel, garnet, tourmaline, anatase, pleonaste, staurolite, allanite, and thorite (Hintze, 1922, p. 351). Crude sand at Barreira and Ponta do Paixao consists of 50— 90 percent of monazite, 6—43 percent of ilmenite, and 4—26 percent of zircon and quartz (Leonardos, 1937a, p. 12). No estimates of the sizes of the placers are given in the literature; however, it has been stated that erosion of sea cliffs by wave action in the vicinity of Prado annually frees 1,000 tons of sand having 70-7 5 percent of monazite (Gottschalk, 1915, p. 903; Frey- berg, 1934, p. 37 8). A Wide range in the abundance of thorium oxide is reported for monazite from Prado. Concentrates of varying degrees of purity were analyzed by Herzfeld and Korn in 1900 and reported to contain from 1.50 to 3.50 percent of Th02 (Leonardos, 1937b, p. 558). Concentrates analyzed by Souza Carneiro contained 1.1—7.6 percent of Th02 (Leonardos, 1937b, p. 559). Monazite sand from Prado analyzed in 1900 at the Escola Minas Ouro Preto contained the following amount of thorium oxide (Moraes, Barbosa, and others, 1937, p. 132; Leonardos, 1937a, p. 13; Lisboa, 1950, p. 28): were Percent (Ce, La, Nd, 1%).03 ________________________ 62.70 v.0. _____________________________________ 3. 00 T1102 _____________________________________ 3. 50 13.05 _____________________________________ 27. 00 A1203 _____________________________________ 3. 00 Fe203 _____________________________________ 2. 50 Total _______________________________ 101. 70 Monazite from Comoxatiba is variously reported to have 7.1-11.1 percent of ThO2 (Leonardos, 1937a, p. 13), or 5.75 percent of Th0; (Leao, 1939, p. 163). 291 Analyses by Souza Carneiro of monazite or monazite concentrates from Curumuxatiba disclose 1.1—11.1 percent of Th0, (in Leonardos, 1937b, p 559). Several small placers on the shore and at the mouths of streams north of Prado at Ponta J uacema (Enseada de J oacema) and Caraiva (Carahyba) have sand which contains almost 25—30 percent of monazite. Monazite from the placers at Caraiva has 5—5.5 percent of Th02 (Leonardos, 1937a, p. 12; Gottschalk, 1915, p. 904; Hintze, 1922, p. 351; Freyberg, 1934, p. 378). The Porto Seguro placer district extends northward along the coast of Bahia from Trancoso to Santa Cruz. Beaches around the city of Trancoso are monazite bearing. In the vicinity of Porto Seguro, monazite occurs at Nossa Senhora da Ajuda (Ajuda), Rio da Villa, Toque-Toque, Rio sac Francisco, and Porto Seguro. According to Leonardos (1937a, p. 12) the crude sand from Toque—Toque contains 55—65 percent of monazite, 20—21 percent of ilmenite, 15 percent of zircon, and 2 percent of quartz. Concentrates from the Porto Seguro district have 7 6—85 percent of mona- zite, 4—11 percent of ilmenite, and 12 percent of zircon and quartz. Monazite, possibly meaning monazite con- centrate, from Toque—Toque has 1.4—7.3 percent of Th02, and the thorium oxide content was said (Leon- ardos, 1937a, p. 12) to exceed 6 or 7 percent in some analyses. Monazite concentrates from the mouth of the Rio Santa Cruz and the beaches at the city of Santa Cruz contain from 1.1 to 9.4 percent of ThOz (Leonardos, 1937a, p. 12). Stream and beach deposits at the mouth of the Rio J equitinhonha and at the mouth of the Rio Pardo at Canavieiras are monazite bearing. The placers at Ca- navieiras are the most northerly beach deposits with significant amounts of monazite that have been observed in Brazil. PARAiBA no NORTE An insignificant amount of monazite and rutile is associated with large beach and dune deposits of ilmen- ite and zircon at Cunhafi in Paraiba do Norte (Gill- son, 1950, p. 692). BRITISH GUIANA Monazite in British Guiana was discovered in 1934 by Grantham in concentrates made from alluvium in streams draining a wide area of the southwestern part of the Kanuku Mountains (Grantham, 1937 , p. 4). It was not found in large concentrations. Reports of similar monazite-bearing concentrates from the same general area, between the Takatu and Rupununi Rivers, were given by Smith Bracewell in 1941 (Henderson, Gr., 1952, p. 125) and 1946 (Brace- 292 well, 1946, p. 37). Monazite was tentatively identified with heavy minerals from red clay adjacent to biotite granite exposed 3.5 miles southwest of Wabwak Moun- tain in the Kanuku Mountains (Henderson, G., 1951, p. 34—35). Henderson also tentatively identified it in concentrates from the Marmiswau and Moriwau Rivers, tributaries to the Rupununi River near Wab- wak Mountain, and in concentrates from Tutuwa and \Vuratwau Creeks in the same area. The plutonic rocks exposed in the Kanuku Moun- tains are granulite, sillimanite-garnet gneiss, and gran— ite. Monazite is an accessory mineral in the sillimanite gneiss (Bracewell, 1947, geologic map; Matthews, P. F. P., 1953, p. 87—88). The economic geology of the monazite placers in the Rupununi district was described by Dujardin (1955). He found the stream placers to have scant lateral ex- tent, to be shallow, and to contain from a few hundred to several tens of thousands of cubic yards of gravel. The arithmetical average tenor of 15 samples of sand and gravel taken from the richest stream in the dis- trict, Wurriwia Creek, was 7.2 pounds of monazite per cubic yard. The samples ranged in tenor from 1.87 to 14.5 pounds of monazite per cubic yard. Silt and clay taken about a mile from the head of Wurriwia Creek contained 1.25 pounds of monazite per cubic yard. The area is remote and relatively undeveloped. No mona- zite had been produced in the Rupununi district or elsewhere in British Guiana as of 1958, though some mining companies were reported in 1956 to be investi- gating monazite deposits near the boundary between British Guiana and Brazil (Mining World, 1956). CHILE Monazite was mentioned by Falke (1936, p. 588) as a possible accessory mineral in fluvio-marine gold pla- cers on the Isla de Chiloé, but none of the deposits was specifically said to have monazite. The placers are grouped into four areas on the west coast of the island. From south to north they are the Punta Catizo-Punta Checo area, the Rahue-Cucoa area, the vicinity of Pu- millahue, and the Ancud-Chacoa area. COLOMBIA Detrital monazite is in gold placers along the Rio Chico (Lleras Codazzi, 1916, p. 8; 1927, p. 94; Scheibe, 1931, p. 85) in Antioquia, Colombia. An early account of a concentrate from the Rio Chico, published by Damour and Des Cloizeaux in 1857 (p. 445, 447), lists monazite as one of the heavy minerals. Other heavy minerals in the concentrate were gold, almandine, zir- con, ilmenite, and sparse columbite, kyanite, wulfenite, and rutile. Damour and Des Cloizeaux were unable THE GEOLOGIC OCCURRENCE OF MONAZITE to find thorium in the monazite. Their analysis shows 29.10 percent of P205, 46.14 percent of Ce203, and 24.5 percent of La203. The Rio Chico drains the west margin of a mass of granodiorite and monzonite of probable Ordovician age that forms a batholith in crystalline schist (West, R. C., 1952, p. 20—29). Spread out over the batholith are deeply dissected fluvioglacial and fluvial sediments, possibly Pleistocene in age, which contain rich gold placers. The amount of monazite from the placers appears to be small (Davidson, 1953, p. 76). Although gold has been mined in the region since pre-Columbian times, no monazite has been produced. An old mineralogical analysis of a concentrate from Zaragoza shows a trace of monazite, dominant ilmen- ite and zircon, and rare magnetite and chromite (Day and Richards, 1906b, p. 1222—1223): Pounds per short ton Ilmenite ___________________________________ 1, 484 Zircon _____________________________________ 302 Quartz ____________________________________ 1 92 Chromite __________________________________ 1 4 Magnetite _________________________________ 8 Monazite __________________________________ Trace FALKLAND ISLANDS Beach placers containing monazite are known along the Falkland Islands, but they are of no economic value (Davidson, 1956a, p. 202). FRENCH GUIANA Monazite is a minor accessory mineral in pegmatite veins that occur as zones in, and grade into, granite exposed in the Courcibo River and Leblond Creek in the drainage basin of the Sinnamary River (Choubert, 1949, p. 102). The pegmatites are composed of micro- cline, plagioclase, biotite, and garnet. Black sand from beaches in the vicinity of Cayenne consists of 75 percent of magnetite, 18 percent of ilmen- ite, 3 percent of zircon, and 4 percent of other miner- als including monazite, rutile, sillimanite, garnet, staurolite, sphene, tourmaline, and topaz (Lebedefl', 1935, p. 406—407). Monazite has not been mined in French Guiana. PERU Monazite was found in sand in the Rio Pacasmayo in 1901 by Denegri (1906, p. 75) and was later shown by Freire Villafane (1950, p. 760) to occur along the coast from Pacasmayo to Sechura in beach sand and fine-grained dune sand. An analysis of a zircon-rich concentrate from the Rio Pacasmayo showed 1.5 per- SOUT’H AME RICA cent of T1102 and some cerium earths (Weckwarth, 1908, p. 18). Monazite occurs as megascopic chocolate-brown crys— tals in pegmatite at the Tarcominas mine in the vicin- ity of Pampacolca, Castilla, Departmento de Arequipa. The pegmatite dikes are injected into gneiss, granite, and granodiorite. The gneiss is of sedimentary origin and is composed of muscovite, chlorite, epidote, garnet, plagioclase, and quartz. The granite and granodiorite are epidote bearing and are Mesozoic in age (Freire Villafane, 1948, p. 2—6). Accessory monazite is com- mon in the pegmatite dikes in the region. Dominant minerals are kaolinized feldspar, quartz, muscovite, and biotite. Other minor accessory minerals are fer- gusonite, uraninite, apatite, zircon, magnetite, ilmen- ite, pyrite, chalcopyrite, and arsenopyrite (Freire Vil- lafane, 1950, p. 758; 1951, maps). Monazite has not been mined in Peru. SURINAM Monazite was recognized as early as 1908 (Middel- berg, 1908, p. 6—7) among the heavy minerals accom- panying gold in placers overlying schist and gneiss and in the savannahs of Surinam (Koloniaal Museum Haarlem Bull, 1909). It was again reported in 1917 (Indische Mercuur, 1917). Monazite is described by Ijzerman (1931, p. 40, 201—202) as a fairly common but minor accessory mineral in granites and unmeta- morphosed sediments in Surinam. Accessory monazite was observed by Ijzerman (1931, p. 289) in thin sections of the microcline-rich biotite granite at Cassipora on the lower Suriname River and in porphyritic biotite granite in the upper part of the basin of the Suriname River at Damanallé on the Pi- kien Rio, and at Goddo and Awa Fall on the Gran Rio (Ijzerman, 1931, p. 211—212). In the drainage basin of the Tapanahony River, porphyritic granite exposed on the Paloemeu River at the foot of a monad- nock called Kassikassima, and nonporphyritic granite in the monadnock itself, contain monazite (Ijzerman, 1931, p. 216). Granite gneiss from Longoston on the Coppen'ame River is monazite bearing (Ijzerman, 1931, p. 282). The accessory monazite in these granites shows no distinct crystal shape, and rounded edges are common. Some grains of monazite have inclusions of zircon and apatite, but other accessory minerals common in the granites, like allanite, magnetite, ilmenite, pyrite, sphene, and primary epidote, are not included in the monazite. Ijzerman (1931, p. 202) interpreted these relations to mean that monazite crystallized as an early accessory mineral preceded only by zircon and apatite. 293 Monazite does not occur in Surinam granites that have primary epidote. Monazite was not identified by Ijzerman (1931, p. 362—373) in thin sections of sillimanite gneisses and schists from Surinam although it had been found by Middelberg (1908, p. 6—7) in placers overlying schist and gneiss. Minor accessory monazite is associated with mag- netite, ilmenite, leucoxene, rutile, muscovite, silliman- ite, kyanite, andalusite, tourmaline, zircon, and garnet in continental sediments obtained from wells drilled about 25 miles south of Paramaribo (Ijzerman, 1931, p. 44), but it was not reported by Kiel (1955, p. 95) to be among the heavy minerals in the sedimentary rocks of the coastal plain of northeastern Surinam. Monazite has not been mined in Surinam. The mona- zite in the gold placers was regarded as uneconomic in 1908 (Middelberg, 1908, p. 7). URUGUAY As early as 1889 detrital monazite had been observed on the Uruguyan banks of the Rio de la Plata at Pun~ ta Caballos (Derby, 1889, p. 113; Johnstone, 1914, p. 58), but it was not until the 1950’s that studies of the coastal placers were undertaken. Four recent papers discuss heavy minerals along the South Atlantic coast of Uruguay and indicate interest in their commercial possibilities as sources for ilmenite and monazite (Géni, 1950, p. 102, 109; Ellis and Mercatini, 1955, p. 285; Jones, Gr. H., 1956, p. 91—92, 106; Bogert, 1959). The following account is drawn from these reports. The heavy minerals are found in the Departamento de Canelones and occur intermittently along the coast eastward from Montevideo for 220 miles to the Bra- zilian frontier. Included among the heavy minerals are ilmenite, zircon, monazite, tourmaline, pyroxene, almandine, spessartite, pyrope, apatite, rutile, beryl, lapislazuli, brookite, epidote, kyanite, staurolite, horn- blende, chromite, and garnierite. Originally these min- erals occurred in the basement complex of Early Pre- cambrian age. This basement complex consists of highly contorted garnetiferous biotite gneiss, migma- tite of lower and middle subfacies of the amphibolite facies, granite, and pegmatite. They are exposed in the northern part of the Departamento de Canelones, but in the southern part they are covered by sedi- mentary rocks of Tertiary and Quarternary age which are as much as 200 feet thick. The sedimentary rocks have served as intermediate hosts for the heavy min- erals, and where they have been eroded the heavy minerals have been further concentrated on the beaches. The coast of Uruguay in this area is a flat uplifted shoreline composed of old barrier beaches and offshore 294 bars. Behind these features are silted—up lagoons, swamps, and sand dunes. The dunes occupy sandy zones about a mile wide parallel to the shore. The entire southern coast contains heavy minerals, but the richest concentrates are at Atlantida (Atlantida Beach) about 25 miles east of Montevideo. Other beaches with notable deposits of black sand are La Floresta, Soils, and Bella Vista. Lower concentrations but greater quantities of heavy minerals are found along the beaches at Costa Azul, San Luis, La Pedrera, Aguas Dulces, and La Coronilla. The beaches are 100—150 feet wide between the high tide line and the first growth of vegetation. Samples from the upper 1.5 feet of sand on parts of the beach at Atlantida contained 12.3—76.2 percent of heavy minerals as reported by Bogert (1959) or 27.6—56.5 percent as reported by G. H. Jones (1956, p. 91). At Atlantida the zone of maximum concentration is 9,000 feet long, 70 feet wide, and 2 feet deep. The sand contains an average of 30 percent of heavy minerals consisting mainly of ilmenite (Bogert, 1959, p. 49): Percent of average concen- trate Ilmenite ___________________________________ 82. 2 Zircon _____________________________________ 5. 4 Monazite __________________________________ 3. 2 Magnetite _________________________________ 2. 5 Rutile _____________________________________ 1. 0 Various silicates ____________________________ 2. 1 Residue ___________________________________ 3. 6 Total ________________________________ 100. 0 Monazite from Atlantida contains 4.1 percent of Th02 (Bogert, 1959, p. 49). Beaches at La Floresta and eastward at Solis and Bella Vista contain streaks of sand said to have re- spectively 52.4, 16.7, and 18.4 percent of heavy min- erals. Locally zircon becomes nearly as abundant as ilmenite in the placers, but monazite seldom exceeds 5 percent of the concentrate. VENEZUELA Sparse grains of monazite occur in assemblages of heavy minerals separated from oil-bearing nearshore marine sandstone of Eocene age exposed east of Lake Maracaibo (Sutton, 1946, p. 1675—1676). The sand- stone crops out on the Potreritos Ranch in the District of Bolivar, Zulia. In approximate order of abundance the heavy minerals in the sandstone are muscovite, tourmaline, zircon, leucoxene, chloritoid, garnet, mag- netite, hematite, barite, ilmenite, rutile, pyrite, anatase, brookite, chlorite, monazite, and amphibole. Monazite is unreported from the other sedimentary rocks of the Maracaibo Lowland (Depresién de Mara- THE GEOLOGIC OCCURRENCE OF MONAZITE caibo) which range in age from Devonian to Recent. It probably originates as a rare accessory mineral in the metamorphic and igneous rocks of the Andes de Mérida and Sierra de Perija which form the rim of the Maracaibo Lowland. BIBLIOGRAPHY Abbott, A. T., 1954, Monazite deposits in calcareous rocks, northern Lemhi County, Idaho: Idaho Bur. Mines and Geology Pamph. 99, 24 p. Abreu, S. F. de, 1937, As areias monaziticas nos Estados do Espirito Santo 6 Rio de Janeiro: Brasileira Chimica (Sci. e Industria) Rev., v. 4, no. 24, p. 450-454. Adams, J. A. S., Richardson, J. E., and Templeton, C. C., 1958, Determinations of thorium and uranium in sedi- mentary rocks by two independent methods: Geochim. et Cosmochim. Acta, v. 13, no. 4, p. 270—279. Adams, J. A. S., and Weaver, C. E., 1958, Thorium-to-uranium ratios as indicators of sedimentary processes—example of concept of geochemical facies: Am. Assoc. Petroleum Geol- ogists Bull., v. 42, no. 2, p. 387—430. Ahlfeld, Friedrich (Federico), 1931, The tin ores of Uncia- Llallagua, Bolivia: Econ. Geology, v. 26, no. 3, p. 241— 257. 1954, Los yacimientos minerales de Bolivia: Imprenta Indus, 277 p. Ahlfeld, Friedrich (Federico), and Angelelli, Victorio, 1948, Las especies minerales de la Repfiblica Argentina: Univ. Nae. Tucuman, Inst. Geologia y Mineria Pub. 458, 304 p. Ahlfeld, Friedrich (Federico), and Munoz Reyes, J., 1939, Die Bodenschatze Boliviens: Berlin, Gebriider Bornt- raeger., 199 p. 1955, Las especies minerales de Bolivia [3d ed.]: La Paz, Banco Minero de Bolivia, 180 p. Ahrens, L. H., 1955, The convergent lead ages of the oldest monazites and uraninites (Rhodesia, Manitoba, Madagas- car, and Transvaal): Geochim. et Cosmochim. Acta, v. 7, nos. 5—6, p. 294—300. Aithal, V. S., 1955, Determination of thorium and uranium concentration ratios of Indian rocks and minerals: Jour. Sci. Indus. Research, v. 14B, no. 10, p. 519—523. Alexander, A. E., 1934, A petrographic and petrologic study of some continental shelf sediments: Jour. Sed. Petrology, v. 4, no. 1, p. 12—22. Alexander, J. B., 1939, The geology and physiography of Mzim- ba District: Nyasaland Protectorate Geol. Survey Dept. Ann. Rept., 1938, p. 18—21. Alford, J. R., Kane, J. K., and Marthison, D. M., 1956, Pet- rographic study of beach sands from Cape Henry, Vir- ginia to North Carolina line [abs]: Virginia Jour. Scl., v. 7, no. 4, p. 327. Alfred, Robert, and Schroeder, H. J., 1958, Methods and prac- tices for producing crushed granite, Campbell Limestone 00., Pickens County, S.C.: U.S. Bur. Mines Inf. Clrc. 7857, 24 p. Allen, Fred, 1958, Mineral resourses of North Carolina: Rocks and Minerals, v. 33, nos. 7—8, p. 301. Allen, (Mrs) Fred, 1958, Radioactive minerals in North Carolina: Rocks and Minerals, v. 33, nos. 7—8, p. 328- 329. Bilbao, BIBLIOGRAPHY Allen, J. E., 1956, Titaniferous Cretaceous beach placer in McKinley County, New Mexico [abs]: Geol. Soc. America Bull., v. 67, no. 12, pt. 2, p. 1789. Amato, A. M., 1956, Catalogo de publicaciones de la Direc- cién Nacional de Mineria (incluyendo 10s informes in- editos) : Argentina Direccion Nae. de Mineria, p. 3~96. American Naturalist, 1883, Analyses of some North Carolina minerals: Am. Naturalist, v. 17, pt. 1, p. 313—314. 1889, Monazite from the Villeneuve Mica Mine, Ottawa County, Quebec: Am. Naturalist, v. 23, no. 272, p. 722- 723. 1892, Petrographical news: Am. Naturalist, v. 26, p. 768. Anderson, A. F. S., 1924, The estimation of tin in titanium tailings: Chem. Eng. and Mining Rev., v. 16, p. 196—197. Anderson, A. L., 1930, The geology and mineral resources of the region about Orofino, Idaho: Idaho Bur. Mines and Geology Pamph. 34, 63 p. 1942, Endomorphism of the Idaho batholith: Geol. Soc. America Bull., v. 53, no. 8, p. 1099—1126. 1943, Geology of the gold-bearing lodes of the Rocky Bar district, Elmore County, Idaho: Idaho Bur. Mines and Geology Pamph. 65, 39 p. 1952, Multiple emplacement of the Idaho batholith: Jour. Geology, v. 60, no. 3, p. 255—265. 1958, Uranium, thorium, columbium, and rare earth deposits in the Salmon region, Lemhi County, Idaho: Idaho Bur. Mines and Geology Pamph. 115, 81 p. 1960, Genetic aspects of the monazite and columbium- bearing rutile deposits in northern Lemhi County, Idaho: Econ. Geology, v. 55, no. 6, p. 1179—1201. Anderson, C., 1904, The occurrence of monazite in situ at Blatherarm Creek, near Deepwater, New South Wales: Australian Mus. Recs, v. 5, no. 4, p. 258—262. Anderson, E. C., 1957, The metal resources of New Mexico and their economic features through 1954: New Mexico Bur. Mines and Mineral Resources Bull. 39, 183 p. Angelelli, Victorio, 1950, Recursos minerales de al Repfiblica Argentina; 1, Yacimientos metaliferos: Inst. Nac. Inv. Cienc. Nat. Buenos Aires, Rev., cienc. geol., v. 2, 543 p. 1956, Distribution and characteristics of the uranium deposits and occurrences in the Argentine Republic: In- ternat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 63—74. Anjaneyulu, B. J. N. S. R., 1953, Geology of the coastal strip from Vizagapatam to Pudimadaka with special reference to black sand concentrates: Geol., Mining, Metall. Soc. India Quart. Jour., v. 25, no. 3, p. 89—98. Anthony, J. W., 1948, Radioactive uranium and thorium: Ari- zona Bur. Mines Circ. 13, 22 p. 1957, Hydrothermal synthesis of monazite: Am. Min- eralogist, v. 42, nos. 11—12, p. 904. Arafijo, J. B. de, 1948, Aproveitamento da monazita de S50 .1050 del Rei: Univ. Brasil Escola de Mines e Metalurgia Rev., v. 13, no. 5, p. 14, 47—48. Armstrong, F. C., 1953, Northwest district, in Geologic investi- gations of radioactive deposits—Semiannual progress re- port, June 1 to Nov. 30, 1953: U.S. Geol. Survey TIM—390, p. 216—220, issued by US. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. 1957a, Dismal Swamp placer deposit, Elmore County, Idaho: US. Geol. Survey Bull. 1042—K, p. 383—392. 295 Armstrong, F. C., 1957b, Eastern and central Montana as a pos- sible source area of uranium: Econ. Geology, v. 52, no. 3, p. 211—224. Artini, Ettore, 1915, Sulla presenza della monazite nelle sabbie e nelle arenarie della Somalia meridionale: Reale Accad. Lincei Atti, ser. 5, Bend, C1. sci. 11s., mat. e nat., v. 24, semestre 1, p. 555—558. Atkinson, A. S., 1910, Mining for the rare minerals: Mining Sci., v. 61, p. 76-77. Australia Bureau of Mineral Resources, Geology, and Geo- physics, 1951, Production of principal minerals and metals in Australia: Australian Mineral Industry Econ. Notes and Statistics, v. 4, no. 1, p. 12—17, no. 4, p. 105—111. 1953, Preliminary mineral production statistics, 1952: Australian Mineral Industry Quart. Rev., v. 5, no. 4, p. 98—99. 1954, Preliminary mineral production statistics, 1953: Australian Mineral Industry Quart. Rev., v. 6, no. 4, p. 118—119. Australia Department of National Development, 1956, The natural occurrence of uranium and thorium in Australia: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 91—92. Australian Mining and Engineering Review, 1909a, Recent mineral discoveries and record of boring operations in Northern Territory: Australian Mining and Eng. Rev., v. 1, Feb., p. 162. 1909b, Monazite: Australian Mining and Eng. Rev., v. 1, June, p. 284. Bacon, R. E, 1910, A preliminary study of the effect of tropi- cal sunlight on the atmosphere, with some notes on radio- active phenomena in the Philippines: Philippine Jour. Sci., v. 5, no. 4, see. A, p. 267—280. Bailey, D. K., 1958, Carbonatites in the Refunsa valley, Cen- tral Province: Northern Rhodesia Geol. Survey Rec. for year ending 31st Dec., 1956, p. 35—42. Bain, A. D. N., 1926, The geology of Bauchi Town and sur- rounding district: Nigeria Geol. Survey Bull. 9, p. 38—64. Baker, D. C., Maze, F. F., and Williams, J. M., 1960, Titanium minerals: U.S. Bur. Mines Mineral Trade Notes, v. 50, no. 3, p. 36-37. Baker, D. H., Jr., and Tucker, E. M., 1962, Thorium: U.S. Bur. Mines Minerals Yearbook, 1961, v. 1, p. 1-6 (pre- print). Baker, G. A., 1945, Heavy black sands on some Victorian beaches: Jour. Sed. Petrology, v. 15, no. 1, p. 11—19. 1957, Beach sand concentrate from northern coast of Western Australia: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 709, p. 1. 1959, Cassiterite-bearing heavy mineral concentrates from the upper Latrobe River, Victoria: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 784, p. 1—2. Baker, G. A., and Edwards, A. B., 1956a, Rock specimens and test products from Nungado, Northern Territory: Aus- tralia Sci. and Indus. Research Organization, Minera- graphic Inv. Rept. 673, p. 1—3. 1956b, Coated gold from Astronomer Mine, North Queens- land: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 654, p. 1-2. 1956c, Beach sand from Mallacoota Inlet, eastern Vic- toria: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 650, p. 1—2. 296 Baker, G. A., and Edwards, A. B., 1956d, Heavy black sand, Point Addis, south coast of Victoria: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 642, p. 1—2. 1956e, Heavy mineral concentrates from Mornington District, Victoria: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 652, p. 1—3. 1956f, Gravity concentrates from beach sands at Capel, Western Australia: Australia Sci. and Indus. Research- Organization, Mineragraphic Inv. Rept. 657, p. 1-5. 1957a, Beach sands from the Hey River estuary, north- ern Queensland: Australia Sci. and Indus. Research Or- ganization, Mineragraphic Inv. Rept. 690, p. 1—2. 1957b, Additional samples of beach sand from Mallacoota Inlet, eastern Victoria: Australia Sci. and Indus. Research Organization, Mineragraphic Inv. Rept. 697, p. 1—3. Ball, L. 0., 1905, Gold, platinum, tinstone, and monazite in the beach sands on the South Coast, Queensland: Queensland Geol. Survey Pub. 198, p. 5—19. 1915, The wolfram, molybdenite, and bismuth mines of Bamford, North Queensland: Queensland Geol. Survey Pub. 248, p. 7—78. Ballard, S. M., 1924, Geology and gold resources of Boise Basin, Boise County, Idaho: Idaho Bur. Mines and Geol- ogy Bull. 9, 103 p. Barbosa, Augusto, 1909, Aeria monazitica: Ouro Preto Escola de Minas Annaes, no. 11, p. 125. Barbosa, C. D., 1948. Monazita de Santa Isabel do Rio Prefo: [Brazil] Inst. Nac. Tecnologia Pub. 103, 17 p. Bardill, J. D., 1946, Ferroalloy metallurgy of Japan: Tokyo General Headquarters, Supreme Commander Allied Pow- ers, Nat. Resources Sec. spec. rcpt. 62, p. 3—52. Barker, G. F., 1903, Radioactivity of thorium minerals: Am. Jour. Sci., 4th ser., v. 16, no. 92, p. 161-168. Barlow, N. E., 1934, A list of minerals known to occur in Southern Rhodesia: Rhodesian Mus. Occasional Papers, no. 3, p. 41—48. 1955, The determination of Southern Rhodesian eco— nomic minerals: Southern Rhodesia Geol. Survey Bull. 42, 33 p. Baroch, C. T., 1957, Rare earths: Eng. Mining J our., V. 158, no. 2, p. 107. Baskerville, Charles, 1903, Action of ultra-violet light upon rare earth oxides: Am. Jour. Sci. 4th ser., v. 16, no. 96, p. 465—466. Bates, R. G., and Wedow, Helmuth, Jr., 1953, Preliminary summary review of thorium-bearing mineral occurrences in Alaska: U.S. Geol. Survey Circ. 202, 13 p. Bates, R. L., and Burks, M. R., 1945, Geologic literature of New Mexico through 1944: New Mexico School Mines Bull. 22, 147 p. Beard, R. R., 1930, Property and operation of Patifio Mines and Enterprises at Llallagua, Bolivia: Eng. Mining Jour., v. 130, no. 3, p. 107—109. Beasley, A. W., 1948, Heavy mineral beach sands of southern Queensland: Royal Soc. Queensland Proc., v. 59, pt. 2, no. 4, p. 109—140. 1950, Part 2, Physical and mineralogical composition, mineral descriptions, and origin of the heavy minerals, part 2 of Heavy mineral beach sands of southern Queens- land: Royal Soc. Queensland Proc., v. 61, no. 7, p. 59— 104. 1957, Heavy black sands from Phillip Island, Victoria: Victoria Nat. Mus. Mem. 21, p. 101—115. THE GEOLOGIC OCCURRENCE OF MONAZITE Beck, L. 0., 1842, Mineralogy of New York: Albany, N.Y., W. and A. White and J. Visscher, 536 p. 1850, Report on the mineralogy of New York; com- prising notices of the additions which have been made since 1842: New York State Mus. 3d Ann. Rept., p. 109— 151. Becker, G. F., 1895, Reconnaissance of the gold fields of the southern Appalachians: U.S. Geol. Survey Mineral Re- sources U.S., 1894, pt. 3b, p. 251—319. Béhier, Jean, 1955, Travaux mineralogiques de l’année 1955, m Besairie, Henri, 1955, Rapport annuel du Service Géo- logique pour 1955: [Madagascar] Direction Mines et Géologie, Service Geol., p. 133—142. 1960, Contribution a la minéralogie de Madagascar: Madagascar Service des Mines, Annales gé01., pt. 29, 78 p. Belezkij, Vladimir, 1956, Mineralizagao tantalo—estanifera e uranifera do municipio de S50 Jofio del Rei, Minas Gerais: Brasil Divisao Fomento Producao Mineral B01. 99, p. 1—42. Bell, R. N., 1904, The geology and mineral resources of Idaho: Am. Mining Cong, 7th Ann. Sess, Denver, Proc., pt. 2, p. 200—226 [1905]. 1915, Mining industry of Idaho for the year 1914: Idaho State Inspector of Mines 16th Ann. Rept., 55 p. Bemmelen, R. W. van, 1941, Delfstoffen van Nederlandsch- Indie als Grondstofien der Inheemsche Industrie: Natuurw. tijdschr. Nederlandsch-Indié, v. 101, pt. 1, p. 11—19. 1949, Economic geology, v. 2 of The geology of Indonesia: The Hague, Govt. Printing Ofiice, 265 p. Benge, Elmer, 1907, Philadelphia Mineralogical Club: Mineral Collector, v. 14, no. 3, p. 44—45. Benge, Elmer, and Wherry, E. T., 1907, Directory of the min- eral localities in and around Philadelphia: Mineral Col- lector, v. 14, no. 1, p. 5—7. Bennett, W. A. G., 1939, Bibliography and index of geology and mineral resources of Washington 1814—1936: Washington Div. Mines and Geology Bull. 35, 140 p. Bensusan, A. J., 1910, The Passagem mine and works: Inst. Mining Metallurgy Trans. [London], v. 20, p. 3—27 [1911]. Besairie, Henri, 1936, La géologie du nord-ouest, premié suite of Recherches géologiques a Madagascar: Acad. Malagache [Tananarive] Mém. 21, 259 p. 1948, L’extréme sud et le sud—sud-est, deuxieme suite of Recherches géologiques a Madagascar: Madagascar Bur. Geol., v. 1, p. 1—127. 1953, Carte miniere et des indices de Madagascar— Notices explicatives: Madagascar Service Géol. Travaux 52, 154 p. 1954, La geologic de la thorianite, in Besairie, Henri, Rapport annuel du Service Géologique pour 1954: [Mada- gascar] Direction Mines et Géologie, Service Geol., p. 107—110. Bessoles, B., 1955, Notice explicative sur la feuille Yalinga- ouest; Afrique équatoriale frangaise, carte géologique de reconnaissance a l’echelle du 1/500.000/ : [French Equato- rial Africa, Service des Mines], 24 p., Paris. Bettencourt Dias, M., 1957, Les pegmatites d’Alto Ligonha: Comm. Tech. Co~op. in Africa South of the Sahara, Comités regionaux Centre, Est et Sud, Conf. de Tanan- arive Avril 1957, Géologie, v. 1, p. 279—282. Bever, J. E., 1952, Petrology of the Gutfey-Micanite region, Colorado [abs]: Am. Mineralogist, v. 37, nos. 3—4, p. 285. BIBLIOGRAPHY Billings, M. P., 1956, Bedrock geology, Part 2 of The geology of New Hampshire: Concord, New Hampshire Plan. Devel. Comm., 203 p. Billings, M. P., and Keevil, N. B., 1946, Petrography and ra- dioactivity of four Paleozoic magma series in New Hampshire: Geol. Soc. America Bull., v. 57, no. 9, p. 797—828. Bisset, C. B., 1956, Annual report of the Geological Survey Department for the year ending 31st December, 1955: Tan- ganyika Geol. Survey Dept. Ann. Rept., 1955, 28 p. Blanchard, Roland, and Hall, Graham, 1942, Rock deforma- tion and mineralization at Mount Isa: Australasian Inst. Mining Metallurgy Pros. new ser., no. 125, p. 1—60. Blaskett, K. S., and Hudson, S. B., 1955, Recovery of mona- zite concentrate from beach sand from Swansea, N.S.W.: Australia Sci. and Indus. Research Organization and Mel- bourne Univ. Mining Dept., Ore—Dressing Inv. Rept. 515, p. 1—14. Bliss, A. D., 1944, The analysis and age of a North Carolina monazite, Part 3 of Radioactive substances: Am. Jour. Sci., V. 242, no. 6, p. 327—330. Bodelsen, 0. W., 1948, Monazite occurrence at Yorktown Heights, N.Y.: Rocks and Minerals, v. 23, no. 11—12, p. 908—910. Bogert, J. R., 1959, Uruguay’s beaches show heavy mineral concentrations: Mining World, v. 21, no. 8, p. 48—49. Bfihm, C. R., 1906, Monazite sand: Eng. Mining Jour., v. 81, no. 18, p. 842. Boltwood, B. B., 1905, The origin of. radium: Philos. Mag, 6th ser., v. 9, no. 52, p. 599—613. Bond, G. W., 1929, The Forbes Reef mineral belt, northern Swaziland: Mining and Indus. Mag. Southern Africa, v. 8, no. 3, p. 657—659. 1930, Lesser known base metals in South Africa: Min- ing and Indus. Mag. Southern Africa, v. 11, no. 9, p. 340— 343. Bondam, J., and S6rensen, H., 1959, Uraniferous nepheline syenites and related rocks in the Ilimaussaq area, Juliane- haab District, Southwest Greenland: Copenhagen Univ. Mineralogiske 0g Geologiske Mus., Commun. géol. 94, p. 555—559. [Reprinted from United Nations Peaceful Uses of Atomic Energy, 2d International Conference, Geneva 1958, Proc., v. 2.] Boos, M. F., 1954, Genesis of Precambrian granitic pegmatites in the Denver Mountain Parks area, Colorado: Geol. Soc. America Bull., v. 65, no. 2, p. 115—141. Borges, D. B., 1937, Areias monaziticas do Espirito Santo: Mineracao e Metallurgia, v. 2, no. 7, p. 66—77. Borrowman, S. R., and Rosenbaum, J. B., 1962, Recovery of thorium from a Wyoming ore: U.S. Bur. Mines Rept. Inv. 5917, p. 1—8. Boudouard, 0., 1898, Sur les sables monazites de la Caroline du Nord: Soc. Chim. Paris Bull., 3d sen, v. 19, no. 1, p. 10—13. Bowie, S. H. U., and Horne, J. E. T., 1952, Cheralite, a new mineral of the monazite group: Great Britain Geol. Sur- vey Atomic Energy Div. Rept. 134, p. 1—5. 1953, Cheralite, a new mineral of the monazite group: Mineralog. Mag, v. 30, no. 221, p. 93—99. Bowling, Leslie, and Wendler, A. P., 1933, Detailed study of some beds, commonly known as Catahoula formation, in Fayette County, Texas, with particular reference to their age: Am. Assoc. Petroleum Geologists Bull., v. 17, no. 5, p. 526—547. 297 Bracewell, Smith, 1946, The geology and mineral resources of British Guiana: British Guiana Geol. Survey Dept. Bull., p. 20—43. 1947, The geology and mineral resources of British Guiana: Imp. Inst. [London] Bull., v. 45, p. 47—65. Bramlette, M. N., 1934, Heavy mineral studies on correlation of sands at Kettleman Hills, California: Am. Assoc. Pe- troleum Geologists Bull., v. 18, no. 12, p. 1559—1576. Brannock, K. C., 1942, Monazite near Mars Hill, NC: Rocks and Minerals, v. 17, no. 3, p. 85, 89. 1943, The Celo cyanite mine: Rocks and Minerals, v. 18, no. 2, p. 47. Brazilian Engineering and Mining Review, 1905, Occurrence and uses of minerals containing thorium: Brazilian Eng. Mining Rev., v. 2, no. 10, p. 152—157. Breger, I. A., 1955, Radioactive equilibrium in ancient marine sediments: Geochim. et Cosmochim. Acta, v. 8, nos. 1—2, p. 63—73. Breithaupt, August, 1829, Ueber den Monazit, eine neue Specie des Mineral-Reichs: Jahrb. Chemie u. Physik 1829, v. 1, no. 3, whole ser. v. 55, new ser. v. 25, p. 301—303. Broadhurst, S. D., 1955, The mining industry in North Caro- lina from 1946 through 1953: North Carolina Div. Miner— al Resources Econ. Paper 66, 99 p. Brooke, H. J ., 1831, On mengite, a new species of mineral; on the character of aeschenite; on sarcolite, as distinct from analcime and gmelinite; with other mineralogical notices: Philos. Mag, v. 10, no. 57, p. 187—191. Brown, J. 0., and Dey, A. K., 1955, India’s mineral wealth: London, Oxford Univ. Press, p. 3—761. Brown, L. G., 1937, Uganda—Its mineral resources and poten- tialities: Sands, Clays, and Minerals, v. 3, no. 2, p. 141— 146, Chatteris, England. Brown, L. J., and Malan, R. C., 1954, Reconnaissance for ura- nium in the south central part of Colorado: U.S. Atomic Energy Comm. RME—1044, p. 1—17. Browning, J. S., Clemmons, B. H., and McVay, T. L., 1956, Re- covery of kyanite and sillimanite from Florida beach sands: U.S. Bur. Mines Rept. Inv. 5274, p. 1—12. Brustier, L., 1934, Sur 1e diamant du Kouango frangais (A.E.F.): Rev. Industrie Minerale Mém., v. 14, pt. 1, p. 435—436. Bryant, Bruce, and Reed, J. 0., Jr., 1960, Road log of the Grandfather Mountain area, North Carolina: Carolina Geol. Soc. Field Trip Guidebook, Oct. 8-9, 1960, p. 1—21. 1962, Structural and metamorphic history of the Grand- father Mountain area, North Carolina—A preliminary re— port: Am. Jour. Sci., v. 260, no. 3, p. 161—180. Bryson, H. J., 1927, The mineral industry in North Carolina for 1924 and 1925: North Carolina, Dept. Conserv. and Devel. Div. Mineral Resources Econ. Paper 60, 64 p. 1937, The mining industry in North Carolina from 1929 to 1936: North Carolina, Dept. Conserv. and Devel. Div. Mineral Resources Econ. Paper 64, 137 p. Bullard, F. M., 1942, Source of beach and river sands on Gulf Coast of Texas: Geol. Soc. America Bull., v. 53, no. 7, p. 1021-1044. Buravas, Saman, 1951, Monazite, in Brown, G. F., Buravas, Saman, Charaljavanaphet, Jumchet, Jalichandra, Nitipat, Johnston, W. D., Jr., Sresthaputra, Vija, and Taylor, G. 0., Jr., 1951, Geologic reconnaissance of the mineral de- posits of Thailand: U.S. Geol. Survey Bull. 984, p. 96. 298 Busz, K., 1914, Ueber den Monazite von Dattas, Diamantina, Provinz Minas Geraes in Brasilien: Neues Jahrb. Minera- logie, Geologie u. Paliiontologie, Beilage-Band 39, p. 482- 499. Butler, G. M., and Mitchell, G. J., 1916, Preliminary survey of the geology and mineral resources of Curry County, Oregon, v. 2 of Mineral Resources of Oregon: Oregon Bur. Mines and Geology, no. 2, 134 p. Buttgenbach, Henri, 1947, Les minéraux de Belgique et du Congo Belge: Liege, H. Vaillant-Carmanne, 573 p. Cahen, Lucien MacGregor, A. M., and Nel, L. T., 1953, Pro- visional table of radioactive ages in Africa, South of the Sahara: Internat. Geol. Cong, 19th, Algiers 1952, Comptes rendus, sec. 1, pt. 1, p. 51-52. California Division of Mines Staff, 1945, Consolidated index of publications of the Division of Mines and predecessor State Mining Bureau 1880—1943 inclusive: California Div. Mines Bull. 131, p. 2—872. California Mining Journal, 1946, Thorium for non-explosive atomic energy found in state: California Mining Jour., v. 15, no. 9, p. 12. Calver, J. L., 1957, Mining and mineral resources: Geol. Survey Bull. 39, 132 p. Cameron, E. N., Larrabee, D. M., McNair, A. H., Page, J. J., Stewart, G. W., and Shainin, V. E., 1954, Pegmatite in- vestigations, 1942—45, in New England: U.S. Geol. Survey Prof. Paper 255, 352 p. Campbell, Arthur, 1941, Idaho’s mineral resources: Northwest Mining News, v. 7, no. 7, p. 3—5. Campbell, Stewart, 1922, Mining situation and outlook in Idaho: Salt Lake Mining Rev., v. 23, no. 19, p. 27—28. Canadian Mining Journal, 1955, Thorium: Canadian Mining Jour., v. 76, no. 2, p. 140. Capps, S. R., 1940, Gold placers of the Secesh Basin, Idaho County, Idaho: Idaho Bur. Mines and Geology Pamph. 52, 42 p. Carne, J. E., 1912, The tungsten-mining industry in New South Wales: New South Wales Dept. Mines, Mineral Re- sources, no. 15, p. 5—102. Carpenter, J. H., Detweiler, J. 0., Jr., Gillson, J. L., Weichel, E. 0., Jr., and Wood, J. P., 1953, Mining and concentra- tion of ilmenite and associated minerals at Trail Ridge, Fla.: Mining Eng., v. 5, no. 8, p. 789-795. Carroll, Dorothy, 1939, Beach sands from. Bunbury, Western Australia: Jour. Sed. Petrology, v. 9, no. 3, p. 95-104. 1940, Possibilities of heavy-mineral correlation of some Permian sedimentary rocks, New South Wales: Am. Assoc. Petroleum Geologists Bull., v. 24, no. 4, p. 636—648. 1941, Heavy residues from some Upper Cretaceous sedi- ments at Gingin, Western Australia: Jour. Sed. Petrol— ogy, v. 11, no. 2, p. 85—91. Carroll, Dorothy, Neuman, R. B., and Jaffe, H. W., 1957, Heavy minerals in arenaceous beds in parts of the Ocoee series, Great Smokey Mountains, Tennessee: Am. Jour. Sci., v. 255, no. 3, p. 175493. Carron, M. K., Naeser, C. R., Rose, H. J., Jr., and Hildebrand, F. A., 1958, Fractional precipitation of rare earths with phosphoric acid: U.S. Geol. Survey Bull. 1036—N, p. 253— 275. Carver, S. R., 1954, Quarterly statistics: Australia Bur. Min- eral Resources, Geology and Geophysics Bull., v. 7, no. 1, pt. 2, p. 1~17, no. 3, pt. 2, p. 1—18. Florida THE GEOLOGIC OCCURRENCE OF MONAZITE Carver, S. R., 1955, Quarterly statistics: Australia Bur. Mineral Resources, Geology and Geophysics Bull., v. 7, no. 4, pt. 2, p. 1—18. Casperson, W. C., 1948, Heavy gravity minerals in the sands of Florida: Rocks and Minerals, v. 23, no. 5, p. 396-397. Catrifi, Luiz, 1951, Minérios de uranio e terio no Brazil: En- genharia, Mineracao e Metalurgia, v. 15, no. 90, p. 289—290. Cazeau, C. F., and Lund, E. H., 1959, Sediments of the Chattahoochee River, Georgia-Alabama: Southeastern Geology, v. 1, no. 2, p. 51—58. Chacko, I. C., 1917, Report on the survey of monazite sand de- posits in Travancore: Travancore Dept. Geol. Rec., p. 1- 17. Chamberlin, B. B., 1888, The minerals of New York County, in- cluding a list complete to date: New York Acad. Sci. Trans, v. 7, nos. 7—8, p. 211—235. Chemical Engineering and Mining Review, 1946, Mining in New Zealand: Chem. Eng. and Mining Rev., v. 39, no. 2, p. 52— 53. Chemical, Metallurgical, and Mining Society of South Africa Journal, 1913, Radio-active minerals in South Africa: Chem, Metall., Mining Soc. South Africa Jour., v. 13, no. 7, p. 323. Chemical Trade Journal and Chemical Engineer, 1915, Indian monazite sands: Chem. Trade Jour. and Chem. Engineer, v. 56, no. 1455, p. 335. 1917a, Monazite sands in Ceylon: Chem. Trade Jour. and Chem. Engineer, v. 61, no. 1595, p. 514. 1917b, Monazite sand: Chem. Trade Jour. and Chem. Engineer, v. 61, no. 1579, p. 165. 1924, Radium and monazite in the Dutch East Indies: Chem. Trade Jour. and Chem. Engineer, v. 75, no. 1950, p. 400. Chemische Industrie, 1924, Funde von radiumhaltigen Erzen and von Monazit: Chem. Industrie, v. 47, no. 34, p. 453. Chemische Zeitschrift, 1904, Monazitsand in Nigeria: Chem. Zeitschr., v. 3, no. 29, p. 813. 1906, Monazitsand und Thorium: 5, no. 2, p. 160. Chen, P. Y., 1953, Heavy mineral deposits of western Taiwan: Taiwan Geol. Survey Bull. 4, p. 13-22. Chenoweth, W. L., 1956, Radioactive titaniferous heavy-min- eral deposits in the San Juan Basin, New Mexico and Colorado [abs]: Geol. Soc. America Bull., v. 67, no. 12, pt. 2, p. 1792. 1957, Radioactive titaniferons heavy-mineral deposits in the San Juan basin, New Mexico and Colorado, in New Mexico Geol. Soc. Guidebook 8th Field Cont, Sept. 1957: p. 212—217. Chernik, G. P., 1908, On the chemical composition of a monazite sand from North America: Acad. Imp. Sci. St. Petersburg Bull., v. 2, p. 243—254. [In Russian.] Chesterman, C. W., 1950, Uranium, thorium, and rare-earth elements, in California Division of Mines Staff, Mineral commodities of California: California Div. Mines Bull. 156, p. 361—363. Chhibber, H. L., 1934, The mineral resources of Burma: Lon- don, Macmillan and 00., p. 1—320. Choubert, Boris, 1949, Géologie et pétrographie de la Guyane francaise: Paris, Office recherche sci. outre-mer, Minis- tere France outre-mer, 120. p. Cirkel, Fritz, 1911, The Amherst (Quebec) graphite deposits: Canadian Mining Inst. Quart. Bull., no. 17, p. 107.115. Chem. Zeitschr., v. BIBLIOGRAPHY Clark, J. W., 1950, Minor metals: U.S. Bur. Mines Minerals Yearbook, 1948, p. 1310—1350. 1951, Uranium, radium, and thorium: U.S. Bur. Mines Minerals Yearbook, 1949, p. 1248—1261. Clark, J. W., and Keiser, H. D., 1953, Uranium, radium, and thorium: U.S. Bur. Mines Minerals Yearbook, 1950, p. 1257—1273. Coates, J. S., 1935, The geology of Ceylon: v. 19, pt. 2, p. 101—187. Collenette, P., 1956, Mineral resources, in Roe, F. W., and others, British Teritories in Borneo, annual report of the Geological Survey Dept. for 1955, 241 p. Colonial Geology and Mineral Resources, 1954, Radioactive dating of monazite from the Rhodesian shield: Colonial Geology and Mineral Resources, v. 4, no. 3, p. 291—292. Colquhoun, D. J., 1962, On surficial sediments in central South Carolina—a progress report: South Carolina Devel. Board Div. Geology Geol. Notes, v. 6, no. 6, p. 63—80. Combe, A. D., and Simmons, W. C., 1933, The geology of the volcanic area of Bufumbira, southwest Uganda Part 1 of The volcanic area of Bufumbira: Uganda Geol. Survey Dept. Mem. 3, p. 1—150. Comité de l’Afrique Francaise [Bulletin], 1904, Les resources minérales de la Nigéria: Comité Afrique Francaise Bull., v. 14, no. 12, p. 387. Congo Belge Bulletin Officiel, 1926a, Mines. Concession a la Société Internationale Forestiere et Miniere du Congo du droit d’exploiter 1a mine de Sili-Ziro: Congo Belge Bull. Ofliciel, v. 19, no. 5, p. 488-495. 1926b, Mines. Compagnie Miniere des Grandes Lacs. Autorisation d’exploiter: Congo Belge Bull. Ofliciel. v. 19, no. 8, p. 784-795. 1933, Mines. La Société des Mines d’Etain du Ruanda— Urandi est autorisée a exploiter les mines de la Makiazo, de la Bijojo, de la Kashuma, de la Mashiga, de la Lu- bwiro, de 1’Agafuguto, de la Musha, de la Rukarara, de la Bugalula et de la borne 35: Congo Belge Bull. Ofliciel, v. 26, pt. 2, no. 9—10, p. 516—534. Connah, T. H., 1938, Mica Creek collection of comparatively rare minerals: Queensland Govt. Mining Jour., v. 39, no. 456, p. 162. Connolly, J. P., 1925, The Etta mine: v. 13, no. 1, p. 18—23. 1933, Geologic history of Black Hills gold placers: South Dakota Geol. Survey Rept. luv. 16, p. 1—15. Connolly, J. P., and O’Harra, C. G., 1929, The mineral wealth of the Black Hills: South Dakota School of Mines Bull. 16, p. 13-418. Cook, E. F., 1957, Radioactive minerals in Idaho: Idaho Bur. Mines and Geology Mineral Resources Rept. 8, 5 p. Cooke, C. W., 1936, Geology of the Coastal Plain of South Spolia Zeylanica, Black Hills Engineer, Carolina: U.S. Geol. Survey Bull. 867, 196 p. 1945, Geology of Florida: Florida Geol. Survey Bull. 29, 339 p. Cooke, C. W., and MacNeil, F. S., 1952, Tertiary stratigraphy of South Carolina: U.S. Geol. Survey Prof. Paper 243-B, p. 19—29. Coomaraswamy, A. K., 1904, Contributions to the geology of Ceylon: III, The Balangoda group: Geol. Mag. [Great Britain], v. 1, no. 8, p. 418—422. 1906, Minerals new or rare in Ceylon: lanica, v. 3, p. 11, 198-199. Spolia Zey. 299 Cooper, Margaret, 1953a, Arizona, Nevada, and New Mexico, Part 1 of Bibliography and index of literature on uranium and thorium and radioactive occurrences in the United States: Geol. Soc. America Bull., v. 64, p. 197-234. 1953b, California, Idaho, Montana, Oregon, Washington, and Wyoming, Part 2 of Bibliography and index of liter- ature on uranium and thorium and radioactive occurrences in the United States: Geol. Soc. America Bull., v. 64, p. 1103-1172. 1954, Colorado and Utah: Part 3 of Bibliography and index of literaure on uranium and thorium and radio- active occurrences in the United States: Geol. Soc. Ameri- ca Bull., v. 65, p. 467—590. 1955, Arkansas, Iowa, Kansas, Louisiana, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, South Da- kota and Texas, Part 4 of Bibliography and index of literature on uranium and thorium and radioactive oc- currences in the United States: Geol. Soc. America Bull., v. 66, p. 257—326. 1958, Connecticut, Delaware, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, and Wisconsin, Part 5 of Bibliography and index of literature on uranium and thorium and radioactive occurrences in the United States: Geol. Soc. America Spec. Paper 67, 472 p. Cooper, W. G. G., 1957, The geology and mineral resources of Nyasaland [revised ed.]: Nyasaland Protectorate Geol. Survey Dept. Bull. 6, p. 3—43. Copland, Maurice, 1905, The monazite deposit at Pinch Swamp Creek, Bonang District, County of Croajingolong: Vic- toria Geol. Survey Bull. 16, p. 3—8. Coppenhagen, J. D. van, 1945, A microscopical investigation of the heavy minerals from alluvial sands of the Breede River: Stellenbosch Univ. Annals, v. 22, sec. A, p. 143- 157. Corin, F., 1931, Spectres d’absorption de quelques minéraux Belges et Congolais: Société sci. Bruxelles Annales, v. 51, sér. 3., no. 2, p. 148—153. Coulson, A. L., 1924, The geology of the Coimadai area, Vic- toria, with special reference to the Limestone Series: Royal Soc. Victoria Proc., new ser., v. 36, pt. 2, p. 163- 174. Councill, R. J., 1955, An introduction to radioactive minerals in North Carolina: North Carolina Div. Mineral Re- sources Inf. Circ. 14, 20 p. Crawford, J. E., 1956, Uranium, radium, and thorium: U.S. Bur. Mines Minerals Yearbook, 1953, v. 1, p. 1203-1244. 1957a, Thorium: Preprint, U.S. Bur. Mines Minerals Yearbook, 1955, p. 1—8. 1957b, Thorium: Eng. Mining Jour., v. 158, no. 2, p. 101. 1958a, Thorium, U.S. Bur. Mines Minerals Yearbook, 1954, v. 1, p. 1157—1164. 1958b, Thorium: U.S. Bur. Mines Minerals Yearbook, 1955, v. 1, p. 1125—1132. 19580, Thorium: U.S. Bur. Mines Minerals Yearbook, 1956, v. 1, p. 1155—1165. Culey, A. G., 1933, Notes on the mineralogy of the Narrabeen series of New South Wales: Royal Soc. New South Wales J our. and Proc., v. 66, pt. 2, p. 344—377. Cumming, G. L., Wilson, J. T., Farquhar, R. M., and Russell, R. D., 1955, Some dates and subdivisions of the Canadian shield: Geol. Assoc. Canada Proc., v. 7, pt. 2, p. 27-79. 300 Cummins, A. B., 1952, Industrial minerals set new production records: Mining Eng., V. 4, no. 2, p. 164—172. Curie, Sklodowska, 1898, Rayons émis par les composes de 1’uranium et du thorium: Acad. sci. [Paris] Comptes rendus, v. 126, p. 1101—1103. Dake, H. C., 1955, Popular prospecting—a field guide for the part-time prospector: Portland, Oreg., Mineralogist Pub. 00., 80 p. Dale, T. N., and Gregory, H. E., 1911, The granites of Con- necticut: U.S. Geol. Survey Bull. 484, 137 p. D'Allier, P., 1906, Les sables de monazite: Nature [Paris], v. 34, no. 1724, p. 30—31. Daly, R. A., 1903, The geology of Ascutney Mountain, Vermont: U.S. Geol. Survey Bull. 209, 122 p. Damour, A., and Des Cloizeaux, A. L. O. L., 1857, Examen de divers échantillons de sables auriferes et platiniferes: Annales Chimie et Physique, 3d ser., v. 51, p. 445—450. Dana, E. S., 1882, On crystals of monazite from Alexander County, North Carolina: Am. Jour. Sci., 3d ser., v. 24, no. 142, p. 247—250. 1884, Mineralogy: 1882, p. 533—549. 1892, The system of mineralogy of James Dwight Dana 1837—1868 [6th ed.]: New York, John Wiley and Sons, 1134 p.; with appendixes I, 75 p. (1899) ; II, 114 p. (1909) ; III, 87 p. (1915). Dana, J. D., 1866, Note on the possible identity of turnerite with monazite: Am. Jour. Sci., 2d ser., v. 42, no. 126, p. 420. Danilchik, Walter, and Tahirkheli, R. A. Khan, 1959, An investigation of alluvial sands for uranium and minerals of economic importance; the Indus, Gilgit, Nagar and Hunza rivers, Gilgit Agency, West Pakistan: Pakistan Geol.. Survey Inf. Release 11, 14 p. David, T. W. E., and Browne, W. B., 1950, The geology of the Commonwealth of Australia, v. 2: London, Edward Arnold and Co., 618 p. Davidson, C. F., 1950, Contribution to discussion on the min- eralogy of some Nile sediments: Geol. Soc. London Quart. J0ur., v. 105, pt. 4, no. 420, p. 533-534. 1953, The gold-uranium ores of the Witwatersrand: Mining Mag. [London], v. 88, no. 2, p. 73-85. 1955, Atomic Energy Division, in Drummond, W. J., 1955, Summary of progress of the Geological Survey of Great Britain and the Museum of Practical Geology: London, Great Britain Geol. Survey, p. 1—88. 1956a, The economic geology of thorium: Mining Mag. [London], v. 94, no. 4, p. 197—208. 1956b, Radioactive minerals in the central African federation: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 207—209. 19560, Radioactive minerals in the British colonies: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 210. 1957, On the occurrence of uranium in ancient conglom- erates: Econ. Geology, v. 52, no. 6, p. 668—693. 1959a, Radioactive minerals in southern Nyasaland: Mining Mag. [London], v. 101, no. 4, p. 178—179. 1959b, Further observations on uraniferous conglomer- ates: Econ. Geology, v. 54, no. 7, p. 1316—1320. Smithsonian Inst. 37th Ann. Rept., THE GEOLOGIC OCCURRENCE OF MONAZITE Davies, K. A., 1942, Mineral resources of Uganda: Uganda Protectorate Geol. Survey, 24 p. Davies, K. A., and Bisset, C. B., 1947, The geology and mineral deposits of Uganda: Imp. Inst. [London] Bull, v. 45, no. 2, p. 161—180. Davis, F. F., and others, 1959, California mining events: Cal- ifornia Div. Mines, Mineral Inf. Service, v. 13, no. 2, p. 14. Day, D. T., 1905a, Black sands of the placer mines of the United States: U.S. 59th Cong, 1st sess., Senate Doc. 65, p. 8—15. 1905b, Second preliminary report on investigation of black sands: U.S. 59th Cong, 1st sess., Senate Doc. 65, p. 15—24. 1907, Black sands of the Pacific coast: Franklin Inst. Jour., v. 164, p. 141—153. Day, D. T., and Richards, R. H., 1906a, Investigation of black sands from placer mines: U.S. Geol. Survey Bull. 285, p. 150—164. 1906b, Black sands of the Pacific slope: U.S. Geol. Survey Mineral Resources U.S. 1905, p. 1175—1246. Debenham, F., 1910, Notes on the geology of King Island, Bass Straits: Royal Soc. New South Wales Jour. and Proc., v. 44, pt. 4, p. 560—576. DeLury, J. S., and Ellsworth, H. V., 1931, Uraninite from the- Huron Claim, Winnipeg River area, S.E. Manitoba: Am. Mineralogist, v. 16, no. 12, p. 569—575. DeMent, Jack, and Dake, H. C., 1948, Handbook of uranium minerals [2 ed.]: Portland, Oreg., Mineralogist Pub. 00., 96 p. Denegri, M. A., 1906, Minerales de thorio: Peru Inf. y Mem., v. 8, no. 5, p. 75—76. Dennis, L. M., 1898, Monazite, in Rothwell, R. P., ed., The min- eral industry, its statistics, technology and trade, in the United States and other countries to the end of 1897: New York, Scientific Publishing Co., v. 6, p. 487—494. Derby, 0. A., 1889, On the occurrence of monazite as an ac- cessory element in rocks: Am. Jour. Sci., ser. 3, v. 37, no. 218, p. 109—113. 1891a, On the separation and study of the heavy ac- cessories of rocks: Rochester Acad. Sci. Proc., v. 1, brochure 2, p. 198406. 1891b, 0n the occurrence of xenotime as an accessory element in rocks: Am. Jour. Sci., ser. 3, v. 41, no. 244, p. 308—311. 1898, On the accessory elements of itacolumite, and the secondary enlargement of tourmaline: Am. Jour. Sci., 4th ser., v. 5, no. 27, p. 187—192. 1899, On the association of argillaceous rocks with quartz veins in the region of Diamantina, Brazil: Am. Jour. Sci., 4th ser., v. 7, no. 41, p. 343356. 1900a, Notes on certain schists of the gold and dia- mond regions of eastern Minas Geraes, Brazil: Am. Jour. Sci., 4th ser., v. 10, no. 57, p. 207—216. 1900b, Notes on monazite: Am. Jour. Sci., 4th ser., v. 10, no. 57, p. 217—221. 1902, On the occurrence of monazite in iron ore and graphite: Am. Jour. Sci., 4th ser., v. 13, no. 75, p. 211- 212. 1905, The Bahia diamond fields: Brazilian Eng. Mining Rev., v. 2, no. 11, p. 163—165. Soc. Ingenieros BIBLIOGRAPHY 301 Derriks, J. J ., and Vaes, J. F., 1956, The Shinkolobwe uranium deposit: current status of our geological and metallo- genic knowledge: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 94—128. Derry, D. R., 1933, Heavy minerals of the Pleistocene beds of the Don Valley, Toronto, Ontario: Jour. Sed. Petrol- ogy, v. 3, no. 3, p. 113—118. Des Cloizeaux, A., 1873, Briefliche Mittheilungen: Deutsche geol. Gesell. Zeitschr., v. 25, p. 568. Dietrich, R. V., 1958, Virginia minerals and rocks [2d ed.]: Virginia Polytech. Inst. Bull., v. 51, no. 4, Eng. Expt. Sta. Sen, no. 122, p. 5—57. 1961, Petrology of the Mount Airy “granite”: Virginia Polytech. Inst. Bull., v. 54, no. 6, Eng. Expt. Sta. Ser., no. 144, p. 2—63. Dixey, Frank, 1926, Geology and mineral resources of Nyasa- land: Mining Mag. [London], v. 34, no. 4, p. 201-212. 1930, Annual report of the Geological Survey Department for the year 1929: Nyasaland Protectorate Geol. Survey Dept. Ann. Rept., 1929, p. 3—11. 1954, Progress report of the Colonial Geological Surveys, 1952—53: Colonial Geology and Mineral Resources, v. 4, p. 44-86. Dixon, D. E., 1926, Bibliography of the geology of Oregon: Oregon Univ. Pub., Geology ser., v. 1, no. 1, p. 4-125. Doelter, C., 1919, Ueber Monazit: Edel—Erden u. Erze, v. 1, no. 1, p. 1-3. Dohm, C. F., 1936, Petrography of two Mississippi River sub- deltas, in Russell, R. J., Howe, H. V., McGuirt, J. H., Dohm, C. F., Hadley, Wade, Kniffen, F. B., and Brown, C. A., 1936, Lower Mississippi River delta reports on the geology of Plaquemines and St. Bernard Parishes: Lou- isiana Geol. Survey Bull. 8, p. 339—396. Donovan, W., 1930, Rocks, minerals, and ores: New Zealand Dominion Lab. Ann. Rept. v. 63, p. 24-25. Dow, V. T., and Batty, J. V., 1961, Reconnaissance of titanif- erous sandstone deposits of Utah, Wyoming, New Mexi- co, and Colorado: US. Bur. Mines Rept. Inv. 5860, p. 1— 52. Drane, B. S., and Stuckey, J. L., 1925, The mineral industry in North Carolina from 1918 to 1923 (inclusive): North Carolina Geol. and Econ. Survey Econ. Paper 55, 104 p. Draper, David, 1911, The diamond-bearing deposits of Baga- gem and Agua Suja in the State of Minas Geraes, Brazil: Geol. Soc. South Africa Trans, v. 14, p. 8—19. Dresser, J. A., and Denis, T. 0., 1949, Geology of Quebec: Quebec Dept. Mines, Geol. Rept. 20, v. 3, p. 1—562. Dropsy, M. U., 1943, Etude granulométrique sur quelques sables de Mauritanie: Soc. francaise minéralogie Bull., v. 66, p. 251—263. Drouin, Alejo, 1911, Las tierras raras y los arenas monaziticas: Minera, Metalurgica, y Ingenieria [Madrid] Rev., v. 62, no. 2304, p. 245—246. Dryden, Lincoln, 1932, Heavy minerals of the Coastal Plain of Maryland: Am. Mineralogist, v. 17, p. 518—521. 1958, Monazite in part of the southern Atlantic Coastal Plain: U.S. Geol. Survey Bull. 1042—L, p. 393—429. Dryden, Lincoln, and Dryden, Clarissa, 1946, Comparative rates of weathering of some common heavy minerals: J our. Sed. Petrology, v. 16, no. 3, p. 91—96. Dujardin, R. A., 1955, Monazite in the Rupununi district British Guiana: British Guiana Geol. Survey Dept. Min- eral Resources Pamph. 6, 5 p. Dunnington, F. P., 1882a, Columbite, orthite and monazite from Amelia Co., Virginia: Am. J our. Sci, 3d sen, v. 24, no. 140, p. 153—154. 1882b, New analyses of columbite and monazite: Am. Naturalist, v. 16, no. 7, p. 611. Dunstan, B., 1905a, Monazite in Queensland: Geol. Survey Pub. 196, pt. 4, p. 11—16. 1905b, Monazite in the beach-sands of Queensland: New Zealand Mines Rec., v. 9, no. 1, p. 37-38. 1906, Annual progress report of the Geological Survey of Queensland for the year 1905: Queensland Dept. Mines Ann. Rept. of Under Secretary for Mines, 1905, p. 153—157. 1913, Queensland mineral index and guide: Queensland Geol. Survey Pub. 241, 1014 p. Dunstan, W. R., 1905, Reports on the results of the mineral survey [of Ceylon] in 1903—4: Great Britain Colonial Oflice, Colonial Repts., Misc. 29, Ceylon, p. 3—34. 1906a, Reports on the mineral survey of Southern Ni- geria for 1903-4 and 1904—5: Great Britain Colonial Ofiice, Colonial Repts., Misc. 33, Southern Nigeria, p. 3—33. 1906b, Report on the results of the mineral survey [of Ceylon] in 1904—5: Great Britain Colonial Oflice, Colonial Repts., Misc. 37, Ceylon, p. 3—45. 1907, Report on the results of the mineral survey [of Ceylon] in 1905—6: Great Britain Colonial Office, Colonial Repts., Misc. 42, Ceylon, p. 3-42. 1908, Report on the results of the mineral survey, 1906—7: Great Britain Colonial Oflice, Colonial Repts., Misc. 48, Nyasaland Protectorate, p. 2—35. 1909, Report on the results of the mineral survey, 1907— 8: Great Britain Colonial Office: Colonial Repts., Misc. 60, Nyasaland Protectorate, p. 2-46. 1910, Report on the results of the mineral survey of Ceylon, 1906—7 and 1907—8: Great Britain Colonial Office: Colonial Repts., Misc. 74, Ceylon, p. 2—70. 1911, Report on the results of the mineral survey, 1908— 9: Great Britain Colonial Office, Colonial Repts., Misc. 80, Nyasaland Protectorate, p. 2—25. 1912, Report on the results of the mineral survey of Southern Nigeria, 1910: Great Britain Colonial Ofiice, Colonial Repts., Misc. 83, Southern Nigeria, p. 3—13. 1913, Report on the results of the mineral survey of Southern Nigeria, 1911: Great Britain Colonial Office, Colonial Repts., Misc. 85, Southern Nigeria, p. 2—12. 1914, Report on the results of the mineral survey of Ceylon (Reports 26 and 27 of series): Great Britain Colonial Office, Colonial Repts., Misc. 87, Ceylon, p. 2—22. Duparc, L., Sabot, R., and Wunder, M., 1913, Contribution a l’étude des minéraux des pegmatites de Madagascar: Soc. frangaise minéralogie Bull., v. 36, p. 5—17. Dutra, C. V., and Murata, K. J., 1954, Spectrochemical de- termination of thorium in monazite by the powder-dc. arc technique: Spectrochim. Acta, v. 6, p. 373—382. Dykes, L. H., 1933, Occurrence of monazite in a granodiorite pegmatite in Riverside County, California [abs]: Geol. Soc. America Bull., v. 44, pt. 1, p. 161. Echo des Mines et de la Metallurgie, 1935, Les recherches minieres en A.O.F. en 1934: Echo Mines et Metallurgie, v. 63, no. 3207, p. 178—179. Economic Weekblad voor Nederlandsch-Indié, 1940, Mijnbouw in 1939: Econ. Weekblad Nederlandsch—Indié, v. 9, no. 16, 17, p. 736—739. Queensland 302 THE GEOLOGIC OCCURRENCE OF MONAZITE Eilertsen, D. E., and Lamb, F. D., 1956, A comprehensive report of exploration by the Bureau of Mines for thorium and radioactive black mineral deposits: US Atomic Energy Comm. RME—3140, 46 p. Ellis, S. 0., and Mercatini, A. F. de, 1955, Identificacién por difraccién de rayos X de los minerales de las arenas ne- gras ilmenitico-monaciticas del littoral Uruguayo: Mon- tevideo Univ. Fac. Ingenieria y Agrimensura Bol., v. 5, no., 10, p. 285—313. Ellsworth, H. V., 1924, The rare element minerals of Canada: Canadian Chemistry and Metallurgy, v. 8, no. 11, p. 261— 263. 1932a, Rare-element minerals of Canada: Canada Geol. Survey Econ. Geology Ser., no. 11, 272 p. 1932b, Monazite colored by carbon from Dickens Town- ship, Nipissing district, Ontario: Am. Mineralogist, v. 17, no. 1, p. 19—28. Emberger, A., 1956, Produits utiles de l’Ankaizina, in Be- sairie, Henri, 1956, Rapport annuel du Service Géologique pour 1956: [Madagascar] Direction Mines et Géologie, Service Geol., p. 53—59. Engenharia, Mineragao e Metalurgia, 1956, Novas 0corréncias de monazita em S50 Paulo: Engenharia Mineracao e Metalurgia, v. 24, no. 141, p. 166. Engineer, 1904, Notes and memoranda: v. 97, p. 13. 1925, Miscellanea: Engineer [London], v. 139, p. 133. Engineering and Mining Journal, 1888, Extended use of some of the rarer minerals: Eng. Mining Jour., v. 46, no. 1, p. 1—2. 1896, Minerals found at Dysartville, N.C.: Eng. Mining Jour., v. 61, no. 18, p. 425—426. 1906a, Monazite [in Tringganu]: Eng. Mining Jour., v. 81, no. 12, p. 605. 1906b, South Carolina: Eng. Mining J our., v. 81, no. 21, p. 1023. 1906c, The monazite industry: Eng. Mining Jour., v. 81, no. 15, p. 713. 1948a, Burma has radioactive minerals: Jour., v. 149, no. 5, p. 153. 1948b, India-Burma: Eng. Mining Jour., v. 149, no. 10, p. 146. 1949, Heavy black sand: Eng. Mining J our., v. 150, no. 11, p. 132. 1950a, The South Fork Mining & Leasing 00.: Eng. Mining Jour., v. 151, no. 2, p. 154. 1950b, Rare Earths, Inc.: Eng. Mining J our., V. 151, no. 10, p. 114. 1950c, Operation of a bucketline dredge on Big Creek: Eng. Mining Jour., v. 151, no. 11, p. 130. 1951, Climax Molybdenum 00.: Eng. Mining Jour., v. 152, no. 7, p. 162. 1952a, Near Mountain Pass, Molybdenum Corporation of America has discovered monazite: Eng. Mining Jour., v. 153, no. 2, p. 166. 1952b, Fred Baumhoi’f, Centerville, Idaho, dredge op- erator: Eng. Mining Jour., v. 153, no. 2, p. 168—169. 1953, In Africa: Eng. Mining Jour., v. 153, no. 11, p. 172. 1957, Prospecting for heavy minerals and rare earths by the Heavy Minerals 00.: Eng. Mining J our., v. 158, no. 3, p. 152. Engineer [London], Eng. Mining 1962, Miscellaneous minerals: Eng. Mining Jour., v. 163, no. 1, p. 112. Erichsen, A. I., 1948, Relatorio da directoria 1947: Brasil Divis‘ao Fomento Producao Mineral B01. 83, p. 9—162. Espenshade, G. H., and Potter, D. B., 1960, Kyanite, silli- manite, and andalusite deposits of the southeastern States: U.S. Geol. Survey Prof. Paper 336, 121 p. Evans, P., Hayman, R. J., and Majeed, M. A., 1934, The graph- ical representation of heavy mineral analyses: Geol., Mining, Metall. Soc. India Quart. Jour., v. 6, no. 2, p. 27- 47. Falconer, J. D., 1912, Nigerian tin; its occurrence and origin: Econ. Geology, v. 7, no. 6, p. 542—546. Falke, Horst, 1936, Los lavaderos de oro en la isla de Chiloé: Chile Dept. Minas y Petréleo Bol., v. 6, no. 62, p. 583—590. Fenner, C. N., 1928, Radioactive minerals from Divino de Uba, Brazil: Am. Jour. Sci., ser. 6, v. 16, no. 95, p. 382—391. 1932, The age of a monazite crystal from Portland, Connecticut: Am. Jour. Sci., ser. 5, v. 23, no. 136, p. 327—333. Fermor, L. L., 1940, The mineral resources of Malaya: Imp. Inst. [London] Bull., v. 38, no. 1, p. 69—82. 1950, The mineral resources of Malaya and other Far Eastern countries: Empire Mining and Metal]. Cong, 4th, Great Britain, Proc., pt. 1, p. 81—109. Fernando, L. J. D., 1948, The geology and mineral deposits of Ceylon: Imp. Inst. [London] Bull., v. 46, p. 303—325. Fettke, C. R., 1914, The Manhattan schist of southeastern New York State and its associated igneous rocks: New York Acad. Sci. Annals, v. 23, p. 193—260. Fisher, L. W., and Doll, C. G., 1927, Remaining counties, Part 2 of Notes on the mineral localities of Rhode Island; Part II, Remaining counties: Am. Mineralogist, v. 12, no. 12, p. 427—436. Fisk, H. N., 1951, Loess and Quaternary geology of the lower Mississippi Valley: Jour. Geology, v. 59, no. 4, p. 333— 356. Fitch, F. H., 1952, The geology and mineral resources of the neighbourhood of Kuantan, Pahang: Malaya, Geol. Sur- vey Dept. Mem. no. 6, new ser., 144 p. 1956, Progress report: British Territories in Borneo, Geol. Survey Dept. Ann. Rept. 1955, p. 176—182. Fitzau, August, 1909, Sud-Polargegenden: Geog. Zeitsch., v. '15, no. 8, p. 480-481. Fleck, Herman, 1909, A brief statement of the rising im- portance of the rare element: Am. Mining Cong, 11th Ann. Sess., 1908, Proc., p. 204—211. Fleischer, Michael, 1953, Recent estimates of the abundances of the elements in the earth’s crusts: U.S. Geol. Survey Circ. 285, 7 p. 1959, Discredited minerals, erikite (=m0nazite): Am. Mineralogist, v. 44, nos. 11—12, p. 1329. Flint, R. F., 1940, Pleistocene features of the Atlantic Coastal Plain: Am. Jour. Sci., v. 238, no. 11, p. 757—787. Florencio, Willer, 1952, Minerais de urano e thfirio: Inst. Tecnologia Indus. Bo]. 11, 137 p., Minas Gerais. Folinsbee, R. E., 1955, Archean monazite in beach concen- trates, Yellowknife geologic province, Northwest Terri- tories, Canada: Royal Soc. Canada Trans, 3d ser., v. 49, sec. 4, p. 7—24. . ... _ BIBLIOGRAPHY Fountainas, Paul, and Ansotte, Max, 1932, Perspectives min— ieres de la région comprise entre le Nil, 1e Lac Victoria ' et la frontiere orientale du Congo Belge: Inst. royal colonial belge, Sec. sci. nat. et méd., Mem., v. 1, no. 5, p. 3—27. Fontaine, W. F., 1883, Notes on the occurrence of certain minerals in Amelia County, Virginia: Am. Jour. Sci., 3d ser., v. 25, no. 149, p. 330—339. Forbes, D., and Dahll, Tellef, 1855, Mineralogiska lagttagelser omkring Arendal 0g Krager6: Nyt Mag. naturvidensk. v. 8, no. 3, p. 213—229, Christiania [Oslo]. Forston, C. W., Jr., and Navarre, A. T., 1959, Monazite-bear- ing pegmatites in the south Georgia Piedmont: Econ. Geology, v. 54, no. 7, p. 1309—1314. Foye, W. G., 1922, Mineral localities in the vicinity of Mid- dletown, Connecticut: Am. Mineralogist, v. 7, no. 1, p. 4—12. 1949, The geology of eastern Connecticut: Geol. Nat. History Survey Bull. 74, 95 p. Foye, W. G., and Lane, A. C., 1934, Correlations by radioac- tive minerals in the metamorpric rocks of southern New England: Am. Jour. Sci., 5th ser., v. 28, no. 164, p. 127—— 138. Franklin Institute Journal, 1908, Monazite and zircon in 1906: Franklin Inst. Jour., v. 165, no. 4, p. 318—319. Franklin, J. W., and Eigo, D. P., 1955, Thorium: Eng. Mining Jour., v. 156, no. 11, p. 75—81. Frayha, Resk, 1947, Monazita, Espirito Santo: Brasil Divisfio Fomento Producao Mineral B01. 83, p. 72—101. Freeman, B. C., 1936, Mineral deposits in Renfrew County and vicinity [Ontario]: Canada Geol. Survey Mem. 195, 34 p. Freire (Freyre) Villafane, Alejandro, 1948, Los minerales ra- dio-actives en la pegmatita de Pampacolca: Soc. Qui- mica Peru 1301., v. 14, no. 1, p. 1—7. 1950, Yacimientos de minerales radioactivos; sus es- tudios en el Peru: Soc. Ingenieros Peru Inf. y Mem., v. 51, no. 12, p. 746—762. 1951, Yacimientos de minerales radioactivos; sus es- tudios en el Peru (cuadros y mapa): Soc. Ingenieros Peru Inf. y Mem., v. 52, nos. 4—6, p. 119—125. Freise, Ferdinand, 1910a, Die Monazitvorkommen im Gebiete des oberen Muriahé—und Pombaflusses im Staate Minas Geraes, Brasilien: Zeitschr. Berg-, Hiitten- u. Salinen- wesen preuss. Staate, v. 58, B, p. 47—64. 1910b, Materialien zur Geschichte des brasilianischen Bergbaus: Archiv Geschichte Naturw. u. Technik, v. 2, p. 425—472, Leipzig. 1911, Betriebs- und Laboratoriumserfahrungen bei der Aufbereitung von Golderzen, Monazit und Wolframit: Os- terreichische Zeitschr. Berg- u. Hfittenwesen, v. 59, no. 18, p. 243—250, 257—263, 272—276, and 284—288. Freyberg, Bruno von, 1934, Die Bodenschiitze des Staates Minas Geraes (Brasilien): Stuttgart, E. Schweizerbart‘- sche Verlagsbuchhandlung, 453 p. Frondel, Clifford, 1958, Systematic mineralogy of uranium and thorium: U.S. Geol. Survey Bull. 1064, 400 p. Fry, Sidney, 1905, Westport School of Mines: New Zealand Dept. Mines, Papers and Repts. Relating to Minerals and Mining, pt. 0—3, p. 26—27. Fryklund, V. 0., Jr., and Holbrook, D. E., 1950, Titanium ore deposits of Hot Spring County, Arkansas: Arkansas Div. Geology Bull. 16, p. 1—173. Connecticut 303 Furia, Antonio, 1939, Coletanea de analises quimicas execu- tadas no periodo de 1889 a 1935: S50 Paulo Inst. Geo- grafico e Geologico B01. 24, p. 5—52. Galbraith, F. W., 1947, Minerals of Arizona [2d ed. rev.]: Arizona Bur. Mines Bull. 153, Geol. ser. 17, 101 p. Gallagher, David, Klepper, M. R., Overstreet, W. C., and Sample, R. D., 1946, Mineral resources of southern Korea: Tokyo, General Headquarters, Supreme Commander Allied Powers, Nat. Resources Sec., 700 p. Gardner, D. E., 1955, Beach-sand heavy-mineral deposits of eastern Australia: Australia Bur. Mineral Resources Geology and Geophysics Bull. 28, p. 8—103. Garson, M. S., 1958a, Investigation of carbonatites and ring structures: Nyasaland Protectorate Geol. Survey Ann. Rept., 1957, p. 7—11. 1958b, The geology of the Senzani area: Nyasaland Protectorate Geol. Survey Ann. Rept., 1957, p. 12-16. Gary, G. L., 1942, Commercial minerals of California: Cal- ifornia Div. Mines Bull. 124, p. 1—165. Genth, F. A., 1862, Contributions to mineralogy: Sci., 2d ser., v. 33, no. 98, p. 190-206. 1871, Appendix, in Kerr, W. C., 1875, Report of the Geo- logical Survey of North Carolina: Raleigh, P. M. Hale and Edwards, Broughton and Co., v. 1, p. 53—88. 1889, Contributions to mineralogy, no. 44: Am. Jour. Sci., 3d ser., v. 38, no. 225, p. 198—203. 1891, The minerals of North Carolina: Survey Bull. 74, 119 p. Genth, F. A., and Kerr, W. 0., 1881, The minerals and mineral localities of North Carolina, being chapter I of the second volume of the geology of North Carolina: Raleigh, P. M. Hale and Edwards, Broughton and 00., p. 1—122. George, D’Arcy, 1949, Mineralogy of uranium and thorium bearing minerals: U.S. Atomic Energy Comm. RMO—563, p. 1—198. Gevers, T. W., 1936, Phases of mineralization in Namaqua- land pegmatites: Geol. Soc. South Africa Trans, v. 39, p. 331—377. Gevers, T. W., and Frommurze, H. F., 1930, The tin-bearing pegmatites of the Erongo area, South-West Africa: Geol. Soc. South Africa Trans, v. 32, p. 111—149. Gianella, V. P., 1928, Minerals of Sespe formation, California, and their bearing on its origin: Am. Assoc. Petroleum Geologists Bull., v. 12, no. 7, p. 747—752. Gibson, J. A., Miller, J. F., Kennedy, P. S., and Rengstorff, G. W. P., 1959, The properties of the rare earth metals and compounds: Columbus, Ohio, Battelle Memorial Inst, 211 p. Gillson, J. L., 1927, Granodiorites in the Pend Oreille district of northern Idaho: Jour. Geology, v. 35, no. 1, p. 1—31. 1950, Deposits of heavy minerals on the Brazilian coast: Am. Inst. Mining Metall. Engineers Trans, v. 187, p. 685— 693. 1957, A geologist looks at industrial minerals: Eng., v. 9, no. 5, p. 550—555. 1958, Industrial minerals: no. 2, p. 93—103, 136. Gindy, A. R., 1961, Radioactivity in monazite, zircon, and “radioactive black" grains in blacksands of Rosetta, Egypt: Econ. Geology, V. 56, no. 2, p. 436—441. Am. J our. U. S. Geol. Mining Mining Cong. Jour., v. 44, 304 Giraud, Pierre, 1955, Les pegmatites de la region d’Andria- mena-Manakana, in Besairie, Henri, 1955, Rapport an- nuel du Service Géologique pour 1955: [Madagascar] Direction Mines et Géologie, Service Geol., p. 37—42. 1957, Le champ pegmatitique de Berere a Madagascar: Comm. Tech. Co-op. in Africa South of the Saraha, Co- mités régionaux Centre, Est et Sud, Conf. de Tananarive Avril 1957, Geologie, v. 1, p. 125—132. Gisolf, W. F., 1926, On the origin of some iron-ores and ser- pentine in the Dutch East Indies: Pan-Pacific Sci. Cong, 3d, Tokyo, Proc., v. 2, p. 1729—1739 [1928]. Glass, J. J., 1934, Rare chemical constituents of Amelia (Vir- ginia) pegmatite dikes, and their mineral sources: Am. Geophys. Union Trans, pt. 1, Repts. and Papers, 15th Ann. Mtg, Washington, D.C., p. 234—237. 1935, The pegmatite minerals from near Amelia, Vir- ginia: Am. Mineralogist, v. 20, no. 11, p. 741—768. Glasstone, Samuel, 1950, Sourcebook on atomic energy: New York, D. Van Nostrand Co., 546 p. Glastonbury, J. 0. G., 1940, Metamorphosed limestones and other calcareous sediments from the moraines—A further collection: Australasian Antarctic Exped. 1911—14 Sci. Repts., ser. A, v. 4, pt. 8, p. 295—322. Gliszczynski, S. von, 1939, Beitrag zur “Isomorphie” von Monazit und Krokoit: Zeitschr. Kristallographie, v. 101, no. 1—2, p. 1—16. Glover, S. L., 1936, Nonmetallic mineral resources of Wash- ington with statistics for 1933: Washington Div. Geol. Bull. 33, 135 p. Goldschmidt, Victor, 1920, Atlas der Krystallformen: Heidel- berg, Carl Winters Universitatsbuchhandlung, v. 6, 208 p. Gofii, J. C., 1950, Arenas negras ilmenitico-monacitas del Uru- guay: Montevideo Fac. Ingenieria Bol. v. 4, no. 1, p. 103— 110. Gonzalez Reyna, J., 1956, Riqueza minera y yacimientos min- erales de Mexico [3d ed.] : Banco de México, Dept. InvesF tigaciones Indus, 497 p. (Internat. Geol. Cong, 20th, Mex- ico 1956). Goodspeed, G. E., and Weymouth, A. A., 1928, Mineral con- stituents and origin of a certain koalin deposit near Spo- kane, Washington: Am. Ceramic Soc. Jour., v. 11, no. 9, p. 687—695. Goodwin, W. L., 1897, Catalogue of minerals in the collection, in Blue, Archibald, 1897, Sixth report of the Bureau of Mines: Ontario Bur. Mines Rept., p. 206—229. Gorceix, Henri, 1883, Note sur quelques minéraux des roches metamorphiques des environs d’Ouro Preto (Minas Gé- raés, Brésil) : Soc. minéralog. France Bull., v. 6, p. 27—34. 1884a, Note sur un oxyde de titane hydrate, avec acide phosphorique et diverses terres, provenant des graviers diamantiferes de Diamantina (Minas-Geraes, Brésil) : Soc. Minéralog. France Bull., v. 7, no. 4, p. 179—182. 1884b, Sur les minéraux qui accompagnet 1e diamant dans le nouveau gisement de Salobro, province de Bahia (Bré- sil): Acad. sci. [Paris] Comptes rendus, v. 98, p. 1446— 1448. 1885a, Estudo sobre a monazita e a xenotima do Bra- zil: Ouro Preto Escola de Minas Annaes, no. 4, p. 29—48. 1885b, Sur des sables a monazite de Caravellas, prov- ince de Bahia (Brésil) : Soc. minéralog. France Bu11., v. 8, no. 1, p. 32—35. THE GEOLOGIC OCCURRENCE OF MONAZITE Gordon, S. G., 1944, The mineralogy of the tin mines of Cerro de Llallagua, Bolivia: Philadelphia Acad. Nat. Sci. Proc., v. 96, p. 279~359. Gottfried, David, 1954, Distribution of uranium in igneous complexes, in Geologic investigations of radioactive de- posits, Semiannual progress report, Dec. 1, 1953, to May 31, 1954: U.S. Geol. Survey TEI—440, p. 202—205. Gottfried, David, Jaffe, H. W., and Senftle, F. E., 1959, Eval- uation of the lead-alpha (Larsen) method for determin- ing ages of igneous rocks: U.S. Geol. Survey Bull. 1097— A, p. 1—63. Gottschalk, A. L. M., 1915, Brazilian monazite sands lie in coas- tal strip: Mining and Eng. World, v. 42, no. 20, p. 903— 904. Graham, W. A. P., 1930, A textural and petrographic study of the Cambrian sandstones of Minnesota: Jour. Geol- ogy, v. 38, no. 8, p. 696—716. Grant, W. H., 1958, The geology of Hart County, Georgia: Georgia Geol. Survey Bull. 67, 75 p. Grantham, D. R., 1937, Report on a short visit to Marudi Mountain gold workings, Rupununi district, 1934: British Guiana Geol. Survey Dept. Bull. 13, p. 1—5 [1939]. Gratacap, L. P., 1909, Geology of the city of New York [3d ed.]: New York, Henry Holt and Co., 232 p. Graton, L. C., 1906, Reconnaissance of some gold and tin deposits of the southern Appalachians: U.S. Geol. Sur- vey Bull. 293, 134 p. Gregory, Maurice, 1948, The geology and mineralization of Minas Geraes, Brazil: Royal Geol. Soc. Cornwall Trans, v. 17, pt. 8, p. 476—492. Greig, C. E., 1924, Mining in Malaya: London, Malayan Inf. Agency, p. 5—58. Griflith, R. F., 1955, Development of monazite exploration tech- niques improves U.S. rare earth and thorium supply: Mining Eng., v. 7, no. 10, p. 930—932. Griflith, R. F., and Overstreet, W. G., 19533, Knob Creek monazite placer, Cleveland County, North Carolina: U.S. Atomic Energy Comm. RME—3112, 30 p. 1953b, Buffalo Creek monazite placer, Cleveland and Lincoln Counties, North Carolina: U.S. Atomic Energy Comm. RME—3113, 17 p. 1953c, Sandy Run Creek monazite placer, Rutherford County, North Carolina: U.S. Atomic Energy Comm. RME-3114, 27 p. Griflith, S. V., 1956, The mineral resources of Burma: Mag. [London], v. 95, no. 1, p. 9—18. Griflitts, W. R., Jahns, R. H., and Lemke, R. W., 1953, Ridge- way-Sandy Ridge district, Virginia and North Carolina, Part 3, and Outlying deposits in Virginia, Part 4, of Mica deposits of the southeastern Piedmont: U.S. Geol. Survey Prof. Paper 248—C, p. 141—202. Griflitts, W. R., and Olson, J. C., 1953a, Shelby-Hickory dis- trict, North Carolina, Part 5, and Outlying deposits in North Carolina, Part 6, of Mica deposits of the south- eastern Piedmont: U.S. Geol. Survey Prof. Paper 248—D, p. 203—293. 1953b, Hartwell district, Georgia and South Carolina, Part 7, and Outlying deposits in South Carolina, Part 8, of Mica deposits of the southeastern Piedmont: U.S. Geol. Survey Prof. Paper 248—E, p. 293—325. Grifiitts, W. R., and Overstreet, W. G., 1952, Granitic rocks of the western Carolina Piedmont: Am. Jour. Sci., v. 250, no. 11, p. 777—789. Mining BIBLIOGRAPHY Grim, R. E., 1936, The Eocene sediments of Mississippi: Mis- sissippi Geol. Survey Bull. 30, p. 5—240. Grund, Herbert, 1956, Vorkommen und Gewinnung von Uran- und Thoriumerzen in den europ‘aischen L'anden und ihren iiberseeischen Gebieten: Glfickauf, v. 92, no. 51—52, p. 1542—1548. Guigues, Jean, 1954, Etude des pagmatites, in Besairie, Henri, Rapport annuel du Service géologique pour 1954: [Ta- nanarive,] Madagascar Direction Mines et Géologie p. 67—71. 1955, Le champ pegmatitique d’Ampandramaika-Mala- kialina, m Besairie, Henri, 1955, Rapport annuel du Service géologique pour 1955: [Tananarive,] Madagascar Direction Mines et Geologic, p. 43—50. Guillou, R. B., and Schmidt, R. G., 1960, Correlation of aero- radioactivity data and arealvgeology in Short papers in the geological sciences: U.S. Geol. Survey Prof. Paper 400—B, p. B119—B121. Guimaraes, C. P., 1939, Djalmaite, a new radioactive mineral: Mineragao e Metalurgia, v. 4, no. 19, p. 35—36. Guimaraes, Djalma, 1925, Breve noticia sobre uma jazida de samarskita, columbita e monazita: Brasil Servico Geo- logico e Mineralogico B01. 13, p. 5—127. 1956, Concentrados estaniferos do municipio de S50 Joao del Rei, Minas Gerais: Brasil Divisao Fomento Produgao Mineral B01. 99, p. 43—42. Guimaraes, Djalma, and Belezkij, Vladimir, 1956, The stano- tantalo—uraniferous deposits and occurrences in the region of S50 J 050 del Rei, Minas Gerais, Brazil: Internat. Cont. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 143—146. Gunter, Herman, 1955, Eleventh biennial report of the Florida Geological Survey covering period of January 1, 1953, through December 31, 1954: Florida Geol. Survey, p. 3—60. Gupta, B. C., 1934, The geology of central Mewar: India Geol. Survey Mem., v. 65, pt. 2, p. 107—169. Gutzeit, G., and Kovaliv, P., 1939, Essais de flottation selective des minéraux constituant les “sables noirs": Archives Sci. Phys. et Nat. [Geneva], 5th ser., v. 21, p. 260—269. Hafer, C., 1941, Hidden of North Carolina: Mineralogist, v. 9, no. 8, p. 291, 305—306. Hahn, A. D., 1962, Reconnaissance of titanium resources on Ship Island, Harrison County, Miss: U.S. Bur. Mines Rept. Inv. 6024, p. 1—24. Hahn, P. D., 1903, Presidential address: South African Assoc. Advancement Sci. Rept., 1st mtg, Cape Town, 1903, p. 37—52. 1912, Thoric dioxide in South African monazites: South African Jour. Sci., v. 9, no. 14, p. 86. Haile, N. S., 1952 Progress report on work in Sarawak: Brit- ish Territories in Borneo, Geol. Survey Dept. Ann Rept. 1950, p. 8—22. 1954, The geology and mineral resources of the Strap and Sadong valleys, West Sarawak, including the Kling- kang Range coal: British Territories in Borneo, Geol. Sur- vey Dept. Mem. 1, p. 1—150. Haitinger, L., and Peters, K., 1904, Notiz fiber das Vorkom- men von Radium im Monazitsand: Kaiserl. Akad. Wiss. Wien, K1. Math.-Naturw., Sitzungber., v. 113, no. 5, pt. 2a, p. 569—570. Hall, A. L., 1918, The geology of the Barberton gold mining district: Union of South Africa Geol. Survey Mem. 9, p. 5—347. 305 Hall, A. L., 1932, The Bushveld igneous complex of the central Transvaal: Union of South Africa Geol. Survey Mem. 28. p. 5—560. 1938, Analyses of rocks, minerals, ores, coal, soils and waters from southern Africa: Union of South Africa Geol. Survey Mem. 32, p. 5—876. Hall, B. A., and Eckelmann, F. D., 1961, Significance of varia- tions in abundance of zircon and statistical parameters of zircon populations in a granodiorite dike, Bradford, Rhode Island: Am. J our. Sci., v. 259, no. 8, p. 622—634. Hamilton, G. N. G., 1939, The geology of the country around Kubuta (southern Swaziland): Geol. Soc. South Africa Trans, v. 41, p. 41—81. Hamilton, S. H., 1899, Monazite in Delaware County, Pa.: Philadelphia Acad. Nat. Sci. Proc., v. 51, pt. 2, p. 377—378. Hammond, R. P., 1947, Technology and uses of monazite sand: Am. Inst. Mining Metall. Engineers Trans, v. 173, p. 596—600. Hanley, J. B., 1946, Lithia pegmatites of the Brown Derby mine, Gunnison County, Colorado [abs]: Am. Mineralo- gist, v. 31, nos. 3—4, p. 197. Hanley, J. B., Heinrich, E. W., and Page, L. R., 1950, Pegma- tite investigations in Colorado, Wyoming, and Utah, 1942- 1944: US Geol. Survey Prof. Paper 227, 125 p. Hansen, L. A., and Caldwell, D. W., 1955, Monazite placers on Rabon Creek, Laurens County, and Big Generostee Creek, Anderson County, South Carolina: US. Atomic Energy Comm. RME—3118, 26 p. Hansen, L. A., and Cuppels, N. P., 1954, Monazite placer on the First Broad River and its tributaries, Cleveland County, North Carolina: US. Atomic Energy Comm. RME—3116, 27 p. 1955, Monazite placer at the junction of the North Tyger River with the Middle Tyger River, Spartanburg County, South Carolina: US Atomic Energy Comm. RME—3117, 23 p. Hansen, L. A., and Theobald, P. K., J r., 1955, Monazite placers of the Broad River and Thicketty Creek, Cherokee County, South Carolina: US. Atomic Energy Comm. RME—3126, 30 p. Hansen, L. A., and White, A. M., 1954, Monazite placers on South Muddy Creek, McDowell County and Silver Creek, Burke County, North Carolina: US. Atomic Energy Comm. RME—3115, 28 p. Harada, Zyunpei, 1948, Chemical analyses of Japanese min- erals (2): Hokkaido Univ. Fac. Sci. J our., 4th ser., v. 7, no. 2, p. 143—210. Harding, J. L., 1960, Heavy-mineral occurrences on islands of the Mississippi Sound and adjacent areas of the mainland [abs]: Geol. Soc. America, Southeastern Sec, Program Mtgs., p. 9—10. Harris, F. E., and Trought, M. E., 1952, Monazite: U.S. Bur. Mines Mineral Trade Notes, v. 35, no. 3, p. 3—61. Harris, H. G., and Willbourn, E. S., 1940, Mining in Malaya: London, Malayan Inf. Agency, p. 9—108. Haseman, J. D., 1921, The humic acid origin of asphalt: Am. Assoc. Petroleum Geologists Bull., v. 5, no. 1, p. 75—79. Hash, L. J ., and Van Horn, E. G., 1951, Sillimanite deposits in North Carolina: North Carolina Div. Mineral Resources Bull. 61, p. 1—51. 306 Haughton, S. H., Frommurze, H. F., Gevers, T. W., Schwellnus, C. M., and Rossouw, P. J., 1939, The geology and mineral deposits of the Omaruru area, South West Africa; an ex- planation of sheet no. 71: Union of South Africa, Geol. Survey, p. 9—160. Heald, M. T., 1950, Structure and petrology of the Lovewell Mountain quadrangle, New Hampshire: Geol. Soc. Amer- ica Bull., v. 61, no. 1, p. 43-89. Hecht, Friedrich, and Kroupa, Edith, 1936, Die Bedeutung der quantitativen Mikroanalyse radioaktiver Mineralien fiir geologische Zeitmessung: Zeitschr, Anal. Chemie, v. 106, no. 3, p. 82—103. Hedlund, D. C., and Olson, J. C. 1961, Four environments of thorium-, niobium-, and rare—earth-bearing minerals in the Powderhorn district of southwestern Colorado in Short papers in the geologic and hydrologic sciences: U.S. Geol. Survey Prof. Paper 424—B, p. B283—B286. Heineman, R. E. S., 1930, A note on the occurrence of monazite in western Arizona: Am. Mineralogist, v. 15, no. 11, p. 536—537. Heinrich, E. W., 1949, Pegmatite mineral deposits in Montana: Montana Bur. Mines and Geology Mem. 28, 56 p. 1950a, Cordierite in pegmatite near Micanite, Colorado: Am. Mineralogist, v. 35, nos. 3—4, p. 173—184. 1950b, Paragenesis of the rhodolite deposit, Masons Mountain, North Carolina: Am. Mineralogist, v. 35, nos. 9—10, p. 764—771. 1953, Zoning in pegmatite districts: v. 38, nos. 1—2, p. 68—87. 1958, Economic geology of the rare-earth elements: Mining Mag. [London], v. 98, no. 5, p. 265—273. Heinrich, E. W., and Bever, J. E., 1957, Selected studies of Colorado pegmatites and sillimanite deposits: Colorado School Mines Quart, v. 52, no. 4, p. 1—55. Heinrich, E. W., Klepper, M. R., and Jahns, R. H., 1953, Thom- aston—Barnesville district, Georgia Part 9, and Outlying deposits in Georgia, Part 10, of Mica deposits of the southeastern Piedmont: U.S. Geol. Survey Prof. Paper 248—F, p. 327—400. Heinrich, E. W., and Olson, J.C., 1953, Alabama district, Part 11 of Mica deposits of the southeastern Piedmont: U.S. Geol. Survey Prof. Paper 248—G, p. 401—462. Henderson, E. P., 1931, Notes on some minerals from the rhodolite quarry near Franklin, North Carolina: Am. Mineralogist, v. 16, no. 12, p. 563—568. Henderson, G., 1951, Report on a preliminary investigation of an occurrence of euxenite in the Kanuku Mountains, British Guiana, m Bracewell, Smith, Report on the Geo- logical Survey Department for the year 1950: British Guiana Geol. Survey Dept. Rept., p. 31—39. 1952, Kanukus expedition, 1951, m Bracewell, Smith, Report on the Geological Survey Department for the year 1951: British Guiana Geol. Survey Dept. Rept., p. 121— 128. Henderson, John, 1917, The geology and mineral resources of the Reefton Subdivision, Westport and North Westland Divisions: New Zealand Geol. Survey Bull. 18, new ser., p. 1—232. 1924, Mineral wealth of New Zealand: Wellington, Govt. Printer, p. 5—24. Hermann, R. 1847a, Untersuchungen russischer Mineralien; 31, Ueber Monazitoi‘d, ein neues Mineral: Jour. prakt. Chemie, v. 1, no. 1, p. 28—32. Am. Mineralogist, THE GEOLOGIC OCCURRENCE OF MONAZITE Hermann, R., 1847b, Untersuchungen russischer Mineralien; 30, Fortgesetzte Untersuchungen fiber die Zusammensetzung des Monazits, namentlich in Beziehung auf den angeblichen Thorerde-Gehalt desselben: Jour. prakt. Chemie, Jahrg. 1847, v. 1, no. 1, p. 21—28. Heron, A. M., 1917, Monazite in Mergui and Tavoy: Geol. Survey Recs, v. 48, pt. 3, p. 179—180. Hess, F. L., 1908, Minerals of the rare-earth metals at Bar— inger Hill, Llano County, Tex.: U.S. Geol. Survey Bull. 340, pt. 1, p. 286—294. 1909, Tin, tungsten, and tantalum deposits of South Dakota: U.S. Geol. Survey Bull. 380, p. 131—163. 1913, Uranium and vanadium: U.S. Geol. Survey Min- eral Resources U.S., 1912, pt. 1, p. 1003—1037. 1937a, Titanium, in Dolbear, S. H., ed., Industrial min- erals and rocks [1st ed.]: Am. Inst. Mining Metall. Eng, p. 893—910. 1937b, Monazite, in Dolbear, S. H., ed., Industrial min- erals and rocks [1st ed.]: Am. Inst. Mining Metall. Eng. p. 523—526. Hess, F. L., and Wells, R. G., 1930, Samarskite from Petaca, New Mexico: Am. Jour. Sci., 5th ser., v. 19, no. 109, p. 17—26. Hewett, D. F., and Crickmay, G. W., 1937, The warm springs of Georgia, their geologic relations and origin, a sum- mary report: U.S. Geol. Survey Water-Supply Paper 819, 40 p. Hickman, R. 0., 1950, Investigation of the Rutherford pegma- tite mine, Amelia County, Va.: U.S. Bur. Mines Rept. Inv. 4641, 6 p. Hidden, W. E., 1880, Addendum, in Genth, F. A., and Kerr, W. C., 1881, The minerals and mineral localities of North Carolina, being chapter I of the second volume of the geology of North Carolina: Raleigh, P. M. Hale and Edwards, Broughton and 00., p. 83—89. ' 1885, Special paper by Wm. Earl Hidden, on the miner- als of North Carolina in the Government Building, in Hanks, H. G., 1885, Fifth annual report of the State mineralogist, for the year ending May 15, 1885: Cali- fornia Mining Bur., p. 182—184. 1888a, New Minerals: New York Acad. Sci. Trans, v. 7, nos. 7—8, p. 237. 1888b, Mineralogical notes: v. 36, no. 215, p. 380—383. 1893, Mineralogical notes: v. 46, no. 274, p. 254—257. 1898, Occurrence of sperrylite in North Carolina: J our. Sci., 4th ser., v. 6, no. 35, p. 381—383. Hidden, W. E., and Pratt, J. H., 1898a, 0n rhodolite, a new variety of garnet: Am. Jour. Sci., 4th ser., v. 5, no. 28, p. 294—296. 1898b, On the associated minerals of rhodolite: Jour. Sci., 4th ser., v. 6, no. 36, p. 463—468. Higgins, H. G., and Carroll, Dorothy, 1940, Mineralogy of some Permian sediments from Western Australia: Geol. Mag. [Great Britain], v. 77, no. 2, p. 145—160. Hill, J. M., 1915, Notes on the fine gold of Snake River, Idaho: U.S. Geol. Survey Bull. 620, pt. 1, p. 271—294. Hill, W. H., 1951, Rare Earth, Inc., redredges Idaho gold placer for monazite: Mining World, v. 13, no. 2, p. 12—14. Hilmy, M. E., 1951, Beach-sands of the Mediterranean coast of Egypt: Jour. Sed. Petrology, v. 21, no. 2, p. 109—120. India Am. Jour. Sci., 3d ser., Am. Journal Sci., 3d ser., Am. Am. BIBLIOGRAPHY Hinckley, L. H., 1945, Minas de mica y columbita en el oriente Boliviano: Mineria Boliviana, v. 2, no. 17, p. 16—17. Hintze, C. A. F., 1922, Handbuch der Mineralogie, v. 1, pt. 1: Berlin, Walter de Gruyter and 00., 720 p.. Hitchen, C. S., 1937, The mining and mineral resources of Kenya Colony: Sands, Clays and Minerals, v. 3, no. 2, p. 87—93, Chatteris, England. HO, O. S., 1953, Zircon and monazite, in Mineral resources of Taiwan: Taihoku, Taiwan Geol. Survey, p. 203—217. Ho, T. L., 1935, Note on some rare earth minerals from Beiyin Obo, Suiyuan: Geol. Soc. China Bull., v. 14, no. 2, p. 279—282. Hoffman, G. G., 1887, Uraninite and monazite from Canada: Am. Jour. Sci., 3d ser., v. 34, no. 199, p. 73—74. 1889, Annotated list of the minerals occurring in Can— ada: Royal Soc. Canada Proc. and Trans, v. 7, sec. 3, p. 65-105. ' 1890, Annotated list of Canadian minerals: Mining Rev., v. 9, no. 12, p. 183-185. Holbrook, D. F., 1948, Titanium in southern Howard County, Arkansas: Arkansas Div. Geology Bull. 13, p. 2—16. Holdsworth, P. R., 1955, Report of the Commissioner of Mines for the biennium ended December 31, 1954: Juneau, Alaska Dept. Mines, p. 3—110. Holmes, Arthur, 1917, The Pre-Cambrian and associated rocks of the district of Mozambique: Geol. Soc. London Quart. Jour., v. 124, pt. 1, no. 293, p. 31—96 [1919]. 1931, Radioactivity and geological time: search Council Bull. 80, p. 124—459. 1949a, The age of uraninite and monazite from the post- Delhi pegmatites of Rajputana: Geol. Mag. [Great Britain], v. 86, no. 5, p. 288-302. 1949b, Exhibit A. Report from Professor Arthur Holmes, University of Edinburgh, in Marble, J. P., chm., Report of the Committee on the Measurement of Geologic Time 1947— 48: Natl. Research Council, Div. Geology and Geography, p. 16—20. 1950, Age of uraninite from a pegmatite near Singar, Gaya District, India: Am. Mineralogist, v. 35, nos. 1—2, p. 19—28. 1954, The oldest dated minerals of the Rhodesian shield: Nature, v. 173, no. 4405, p. 612—614. 1955, Dating the Precambrian of Peninsular India and Ceylon: Geol. Assoc. Canada Proc., v. 7, pt. 2, p. 81—106. Holmes, Arthur, and Cahen, Lucien, 1955, African geochron- ology, results available to 1 September 1954: Colonial Geology and Mineral Resources Quart. Bull., v. 5, p. 3- 39. Holmes, R. J., 1954, A reconnaissance survey of the mineral deposits of Somalia (former Italian Somaliland) : Rome, Italy, U.S. Foreign Operations Adm, Special Mission to Italy for Economic Cooperation, p. 1—83. Homor, R. R., 1918, Notes on the black sand deposits of southern Oregon and northern California: US Bur. Mines Tech. Paper 196, p. 3—42. Hoshina, Masaaki, 1926, Japanese minerals containing rarer elements [abs] : Pan-Pacific Sci. Cong, 3rd, Tokyo, Proc., v. 1, p. 867—868 [1928]. Hotchkiss, Jed, 1884-85. Virginia minerals for the New Or- leans Exposition: The Virginias, v. 5, no. 9, p. 139-140, 153; no. 10, p. 164—169; no. 11, p. 179—186; no. 12, p. 200— 202; v. 6, no. 2, p. 25—27. Houk, L. G., 1946, Monazite sand: U.S. Bur. Mines Inf. Circ. 7233, p. 1—19. Canadian Natl. Re- 307 Houston, J. R., Bates, R. G., Velikanje, R. S., and Wedow, Helmuth, Jr., 1958, Reconnaissance for radioactive de- posits in southeastern Alaska, 1952: US. Geol. Survey Bull. 1058—A, p. 1—31. Houston, J. R., Velikanje, R. S., Bates, R. G., and Wedow, Helmuth, Jr., 1953, Southeastern Alaska, in Wedow, Hel- muth, Jr., and others, 1953, Preliminary summary of re- connaissance for uranium and thorium in Alaska, 1952: U.S. Geol. Survey Circ. 248, p. 6—13. Hovey, E. 0., 1895, Notes on some specimens of minerals from Washington Heights, New York City: Am. Mus. Nat. History Bull., v. 7, p. 341-342. Hsieh, C. Y., 1926, General statement on the mining industry (1918—1925): China Geol. Survey Spec. Rept. 2, p. 1— 362 [In Chinese, English table of contents] 1943, Tin placer deposits in Fuhochungkiang area, north- eastern Kuangsi and southern Hunan, and with a note on the distribution of tin belts in China: Geol. Soc. China Bull., v. 23, nos. 1—2, p. 79-93. Hubbard, C. R., 1955, A survey of the mineral resources of Idaho: Idaho Bur. Mines and Geology Pamph., no. 105, 74 p. Hudson, S. B., 1957, Recovery of monazite from weakly mag- netic beach sand minerals from Swansea, N. S. W.: Aus- tralia Sci. and Indus. Research Organization and Mel- bourne Univ. Mining Dept, Ore-Dressing Inv. Rept. 542, p. 1-12. Hudson, S. B., and Blaskett, K. S., 1958, Recovery of mona- zite from the beach sand deposits of eastern Australia: Australasian Inst. Mining and Metallurgy Proc., no. 186, p. 161-183. Hudspeth, W. R., 1952, Spirals recover heavy mineral by- product—Kings Mountain, N.C.: Mining Eng., v. 4, no. 8, p. 767. _ Hunter, C. E., 1940, Residual alaskite kaolin deposits of North Carolina: Am. Ceramic Soc. Bull., v. 19, no. 3, p. 98—103. Hunter, C. E., and White, W. A., 1946, Occurrences of silli- manite in North Carolina: North Carolina Div. Mineral Resources Inf. Circ. 4, p. 1—12. Hunter, D. R., 1957, The geology, petrology and classifica- tion of the Swaziland granites and gneisses: Geol. Soc. South Africa Trans, v. 60, p. 85—120. Huntting, M. T., 1956, Metallic minerals, Part 2 of Inventory of Washington minerals: Washington Dept. Conserv. Devel., Div. Mines and Geol. Bull. no. 37, v. 1, p. 4—398. Hurley, P. M., and Fairbairn, H. W., 1957, Abundance and distribution of uranium and thorium in zircon, sphene, apatitie, epidote, and monazite in granitic rocks: Am. Geophys. Union Trans, v. 38, no. 6, p. 939-944. Hurst, V. J., 1953, Heavy minerals in saprolite differentiation: Georgia Geol. Survey Bull. 60, pt. 2, p. 244—264. Hussak, Eugene, 1891, Mineralogische Notizen aus Brazilien (Brookit, Cassiterit, Xenotim, Monazit und Euklas): Tschermaks mineralog. petrog. Mitt, v. 12, no. 1, p. 457— 475. 1899, Mineralogische Notizen aus Brasilien (III Theil) : Tschermaks mineralog. petrog. Mitt, v. 18, no. 4, p. 334— 359. 1909, Ein neues Vorkommen von Phenakit in Brasilien: Centralbl. Mineralogie, Geologie, u. Palaontologie, Jahrg. 1909, p. 268—270. 308 Hussak, Eugene, and Prior, G. T., 1897, Lewisit und Zirkelit, zwei neue brasilische Mineralien: Fortschr. Phys. Materie, v. 53, pt. 1, p. 267—268 [1898]. Hussak, Eugene, and Reitinger, J., 1903, Ueber Monazit, Xenotim, Senait und natiirliches Zirkonozyd aus Brasil- ien: Zeitschr. Kristollographie u. Mineralogie, v. 37, no. 6, p. 550—579. Hutchinson, Arthur, 1909, Mineralogical chemistry: Chem. Soc. [London], Ann. Repts. Prog. Chemistry, v. 6, p. 201— 231. Hutchinson, R. W., and Claus, R. J., 1956, Pegmatite deposits, Alto Ligonha, Portugese East Africa: Econ. Geology, v. 51, no. 8, p. 757—780. Hutton, C. 0., 1940, The titaniferous ironsands of Patea, with an account of the heavy residues in the underlying sedi- mentary series: New Zealand Jour. Sci. and Technology, v. 21, no. 43, p. 1903—2053. 1945, The ironsands of Fitzroy, New Plymouth: New Zealand Jour. Sci. and Technology, v. 26, sec. B, no. 6, p. 291—302. 1950, Studies of heavy detrital minerals: America Bull., v. 61, p. 635—716. 1952, Accessory mineral studies of some California beach sands: U.S. Atomic Energy Comm. RMO—981, p. 3—112. 1953, Final technical report [for May 1, 1951—June 30, 1953]. Part 1, Studies of the minor constituents in some California beach sands, and Part 2, Optical and chemical studies of minerals containing tantalum, titanium and uranium as a preliminary to investigation of the miner- alogy of some Idaho placer deposits: US. Atomic Energy Comm. RME—3049, p. 2—55. Hutton, C. 0., and Turner, F. J., 1936, The heavy minerals of some Cretaceous and Tertiary sediments from Otago and Southland: Royal Soc. New Zealand Trans. and Proc., v. 66, pt. 3, p. 255—274. Hwang, In Chun, and Park, Hi In, 1956, Monazite placer de- posits of the Seoun, Miyang and Ipchang districts, Ansung— gun, Kyonggi—do and Chunan-gun, S. Chungchong-do: Ko- rea Geol. Survey Bull. 1, p. 103—129. [In Korean, English title] Ichimura, Takeshi, 1943, Zircon and corundum deposits in the Manboku—Mahuku district, Sinkitu Prefecture, Taiwan (Formosa): Taihoku Imp. Univ. Fac. Sci. Mem., 3d sen, v. 1, no. 2, p. 1—22. 1948, Zircon and monazite deposits of Taiwan: Geol. Soc. Japan J our., v. 54, no. 639, p. 190—191. [In Japanese] Iddings, J. P., and Cross, Whitman, 1885, On the widespread occurrence of allanite as an accessory constituent of many rocks: Am. Jour. Sci., ser. 3, v. 30, no. 176, p. 108—111. Iimori, Satoyasu, 1929, The uranium-thorium-ratio in mona- zites: Tokyo Inst. Phys. and Chem. Research Sci. Papers, v. 10, no. 188, p. 229—236. [In Japanese] 1942, The occurrence of monazite in Tyosen: Tokyo Inst. Phys. and Chem. Research Bull., v. 21, no. 4, p. 405- 411. [In Japanese] Iimori, Satoyasu, and Yoshimura, Toyofumi, 1929, Geographi- cal distribution of certain minerals in Japan: Tokyo Inst. Phys. and Chem. Research Sci. Papers Supp, v. 10, no. 9, p. 5—46. [In Japanese] Iimori, Satoyasu, Yoshimura, Jun, and Hata, Shin, 1935a, Some pegmatite minerals occuring in Korea: Tokyo Inst. Phys. and Chem. Research Bull., v. 14, no. 9, p. 878—884. [In Japanese] Geol. Soc. THE GEOLOGIC OCCURRENCE OF lVIONAZITE 1935b, The occurrence and distribution of monazite-sand along the Rivers Daidoko and Seisenko, Korea: Tokyo Inst. Phys. and Chem. Research Bull., v. 14, no. 5, p. 351—360. [In Japanese] Iimori, Takeo, 1941, The black monazite occurring in North- east Korea: Tokyo Inst. Phys. and Chem. Research Bull., v. 20, no. 12, p. 1052—1054. [In Japanese] Ijzerman, Robert, 1931, Outline of the geology and petrology of Surinam (Dutch Guiana): Utrecht, Kemink en zoon, 519 p. Illy, P., and Launey, P., 1955, Le granite Taourirt d’ In Tounine et ses minéralisations: Algérie Bur. recherches minieres, sci. et econ. Bull. 3, p. 109—127. Imperial Institute [London], 1905, Monazitic sand from Queens- land: Imp. Inst. [London] Bull., v. 3, no. 3, p. 233-236. 1906, Occurrence of monazite in the tin-bearing alluvium of the Malay Peninsula: Imp. Inst. [London] Bull., v. 4, no. 4, p. 301—309. 1911a, Monazite sand from Travancore, India: Inst. [London] Bull., v. 9, no. 2, p. 103—105. 1911b, “Amang” from the Federated Malay States: Imp. Inst. [London] Bull., v. 9, no. 2, p. 99—102. 1914a, The composition of monazite: Imp. Inst. [Lon- don] Bull., v. 12, no. 1, p. 55—60. 1914b, German East Africa, Part 1 of The economic resources of the German colonies: Imp. Inst. [London] Bull., v. 12, no. 4, p. 580599. 1915, German South-West Africa, Part 2 of The econom- ic resources of the German colonies: Imp Inst. [London] Bull., v. 13, no. 2, p. 233—260. 1916, Recent work on monazite and other thorium minerals in Ceylon: Imp. Inst. [London] Bull., v. 14, no. 3, p. 321—369. 1917, The constitution and work of the Imperial Insti- tute, with special reference to mineral resources: Imp. Inst. [London] Bull., v. 15, no. 3, p. 335—353. 1922, Monazite: Imp. Inst. [London] Bull., v. 20, no. 2, p. 244. 1923, Thorium minerals from Ceylon: don] Bull., v. 21, no. 1, p. 197—198. 1925, Monazite: Imp. Inst. [London] Bull., v. 23, no. 2, p. 238. 1930, Federated Malay States: Bull., v. 28, no. 3, p. 366—367. 1933a, Mineral resources Uganda: Bull., v. 31, no. 2, p. 268—269. 1933b, Empire mineral supplies for chemical industry: Imp. Inst. [London] Bull., v. 31, no. 3, p. 369—385. 1935a, Mineral resources Uganda: Imp. Inst. [London] Bull., v. 33, no. 4, p. 493—494. 1935b, Ilmenite—monazite sands from Travancore: Imp. Inst. [London] Bull., v. 33, no. 3, p. 355—356. 1947, The pegmatites of central Nigeria: [London] Bull. 44, no. 4, p. 408—410. Imperial Mineral Resources Bureau, 1920, Monazite (1913-— 1919), in The mineral industry of the British Empire and foreign countries: London, Imp. Mineral Resources Bur., p. 3—15. 1924, Monazite, in The mineral industry of the British Empire and foreign countries: London, Imp. Mineral Re- sources Bur., p. 1—7. 1925, Monazite, m The mineral industry of the British Empire and foreign countries: London, Imp. Mineral Re- sources Bur., p. 3—13. Imp. Imp. Inst. [Lon- Imp. Inst. [London] Imp. Inst. [London] Imp. Inst. BIBLIOGRAPHY Indische Mercuur, 1917, Mijnbouwkundig onderzoek in Sur- iname: Indische Mercuur, v. 40, no. 9, p. 198. Ito, Teiichi, ed., 1937, Beitrage zur Mineralogie von Japan, new ser., v. 2, 168 p. [In Japanese, English summary.] Itterbeek, A. van, and Van Paemel, 0., 1950, Measurements on the helium content of monazite of Belgian Congo: Bel- gié Koninkl. Vlaamsche Acad. Wetensch. Mededel., Klasse Wetensch., v. 12, no. 10, p. 7—9. Jacob, G., 1916, Brazilian monazite: v. 112, no. 4199, p. 108. Jacobs, E. C., 1934, The mineral resources and industries of Vermont: Vermont Geol. Survey, Rept. State Geologist for 1933-1934, no. 19, p. 1—36. Jacobson, R. R. E., and Webb, J. S., 1946, The pegmatites of central Nigeria: Nigeria Geol. Survey Bull. 17, p. 1—61. Jaffe, Gilbert, and Hughes, J. H., 1953, The radioactivity of bottom sediments in Chesapeake Bay: Am. Geophys. Union Trans, v. 34, no. 4, p. 539—542. Jaffe, H. W., 1955, Precambrian monazite and zircon from the Mountain Pass rare-earth district, San Bernardino County, California: Geol. Soc. America Bull, v. 66, no. 10, p. 1247—1256. Jaffe, H. W., Gottfried, David, Waring, C. L., and Worthing, H. W., 1959, Lead-alpha age determinations of accessory minerals of igneous rocks (1953—1957) : U.S. Geol. Survey Bull. 1097—B, p. 65-148. Jahns, R. H., 1946, Mica deposits of the Petaca District, Rio Arriba County, New Mexico: New Mexico Bur. Mines and Mineral Resources Bull. 25, p. 1—294. 1953, Quantitative analysis of lithium-bearing pegmatite, Mora County, New Mexico, Part 2 of The genesis of peg- matites: Am. Mineralogist, v. 38,»nos. 11—12, p. 1078— 1112. Jahns, R. H., Griflitts, W. R., and Heinrich, E. W., 1952, Gen- eral features, Part 1 of Mica deposits of the southeastern Piedmont: U.S. Geol. Survey Prof. ‘Paper 248—A, p. 1- 102. James, C., 1913, The rare earths of the Carolina monazite sands: Am. Chem. Soc. Jour., v. 35, no. 3, p. 235—239. James, W. F., Lang, A. H., Murphy, Richard, and Kesten, S. N., 1950, Canadian deposits of uranium and thorium: Am. Inst. Mining Metall. Engineers Trans, v. 187, p. 239— 255. Janes, T. H., 1956, Rare, or less common, metals in Canada: Canada Mines Branch, Mineral Resources Div., Inf. Circ. 21, p. 1—16. Janisch, E. P., 1927, The occurrence of phosphates in the Zoutpansberg district of the northern Transvaal: Geol. Soc. South Africa Trans, v. 29, p. 109—135. Japan Geol. Survey, 1956, Natural occurrence of uranium and thorium in Japan: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 174—175. Jarrard, L. D., 1957, Some occurrences of uranium and thori- ium in Montana: Montana Bur. Mines and Geology Misc. Contr. 15, p. 1—90. Jarvis, E. E., 1947, Industry in Malaya: neer, Aug. 7, p. 70—73. Jenks, W. F., 1935, Pegmatites at Collins Hill, Portland, Connecticut: Am. Jour. Sci., ser. 5, v. 30, no. 177, p. 177— 197. Jimbo, Kotora, 1899, Notes on the minerals of Japan: Imp. Univ. Coll. Sci. Jour., v. 11, pt. 2, p. 213—281. Mining Jour. [London], Australasian Engi- Tokyo 309 Johnson, D. H., 1951, Reconnaissance of radioactive rocks of Massachusetts: U.S. Geol. Survey TEI—69, p. 3——18, issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. Johnson, H. S., Jr., 1960, Geologic activities in South Carolina during 1959: South Carolina Devel. Board Div. Geology, Geologic Notes, v. 4, no. 1, p. 1—7. Johnston, W. B., Jr., 1945, Os pegmatitos berilo—tantaliferos da Paraiba e Rio Grande do Norte, no Nordeste do Brasil: Brasil Divisao Fomento Producao Mineral B01. 72, p. 9— 85. Johnstone, S. J., 1914, Monazites from some new localities: Soc. Chem. Industry J our., v. 33, no. 2, p. 55—59. 1918, Monazite: Soc. Chem. Industry Jour. Rev., v. 37, no. 19, p. 373—376. 1948, Minerals for chemical and allied industries: In— dus. Chemist and Chem. Manufacturer, v. 24, no. 284, p. 611—621. Jones, E. L., Jr., 1916, Lode mining in the Quartzburg and Grimes Pass porphyry belt, Boise Basin, Idaho: U.S. Geol. Survey Bull. 640, pt. 1, p. 83-111. Jones, F. A., 1915, The mineral resources of New Mexico: New Mexico Mineral Resources Survey Bull. 1, p. 7—77. Jones, G. H., 1956, Mapa geologico de la regién oriental del Departamento de Canelones: Uruguay Inst. Geol. B01. 34, p. 5—107. [In Spanish, English summary.] Jones, W. B., 1926, Index to the mineral resources of Alabama: Alabama Geol. Survey Bull. 28, p. 9—250. Jones, W. H., 1949a, The monazite bearing sands of the At- lantic beaches: Mineralogist, v. 17, no. 10, p. 457—459. 1949b, The black sands of South Carolina: Mineralo— gist, v. 17, no. 12, p. 580-582. Judd, J. W., and Hidden, W. E., 1899, On a new mode of oc- currence of ruby in North Carolina: Mineralog. Mag, v. 12, no. 56, p. 139—149. Junner, N. R., 1929, Report of the Geological Department for part of the year 1927 and for the year 1928: Sierra Leone Geol. Dept. Rept., p. 1—17. 1935, Report of the Director of the Geological Survey for the financial year 1934—35: Gold Coast Survey Rept. for financial year 1934—35, p. 1—28. 1938, The geology and mineral resources of the Gold Coast: Gold Coast Geol. Survey Bull., 12 p. 1943, The diamond deposits of the Gold Coast with notes on other diamond deposits in West Africa: Gold Coast Geol. Survey Bull. 12, p. 2—52. 1952, Sierra Leone mineral deposits: [London], v. 239, no. 6113, p. 432. 1959, The occurrence of uranium in ancient conglomer— ates: Econ. Geology, v. 54, no. 7, p. 1320—1323. Junner, N. R., and James, W. T., 1947, Chemical analyses of Gold Coast rocks, ores, ~and minerals: Gold Coast Geol. Survey Bull. 15, p. 4—66. Just, Evan, 1937, Geology and economic features of the peg- matites of Taos and Rio Arriba Counties, New Mexico: New Mexico Bur. Mines and Mineral Resources Bull. 13, p. 3—73. Kaiser, E. P., 1956, Preliminary report on the geology and de- posits of monazite, thorlte, and niobium-bearing rutile of the Mineral Hill district, Lemhi County, Idaho: U.S. Geol. Survey open-file report 390, p. 2—41. Mining J our. 310 Karkhanavala, M. D., 1956, The synthesis of huttonite and monazite: Current Sci. [Bangalore], v. 25, no. 5, p. 166—167. Karkhanavala, M. D., and Shankar, J., 1954, An X-ray study of natural monazite: I: Indian Acad. Sci. Proc., v. 40, sec. A, p. 67—71. Kartha, K. N., 1955, Studies on monazite: Travancore Univ. Central Research Inst. Bull., ser. A, v. 4, no 1, p. 53—62. Kato, Toshio, 1958, A study on monazite from the Ebisu mine, Gifu Prefecture: Mineralogical Jour., v. 2, no. 4, p. 224— 235. Kauffman, A. J., Jr., and Baber, K. D., 1956, Potential of heavy-mineral-bearing alluvial deposits in the Pacific northwest: U.S. Bur. Mines Inf. Circ. 7767, p. 1—36. Kauffman, A. J., Jr., and Jaffe, H. W., 1946, Chevkinite (Tscheffkinite) from Arizona: Am. Mineralogist, v. 31, nos. 11—12, p. 582-588. Kay, G. F., and Graham, J. B., 1943, The Illinoian and post- Illinoian Pleistocene geology of Iowa: Iowa Geol. Survey Repts. and Papers, v. 38, p. 3-262. Keevil, N. B., Larsen, E. S., and Wank, F. J., 1944, The Ayer granite-migmatite at Chelmsford, Mass, Part 6 of The distribution of helium and radioactivity in rocks: Am. Jour. Sci., v. 242, no. 7, p. 345-353. Keiser, H. D., 1954, Uranium, radium, and thorium: U.S. Bur. Mines Minerals Yearbook, 1951, p. 1229—1314. 1955, Uranium, radium, and thorium: U.S. Bur. Mines Minerals Yearbook, 1952, v. 1, p. 1083-1108. Keith, Arthur, and Sterrett, D. B., 1931, Description of the Gaffney and Kings Mountain quadrangles [South Caro— lina-North Carolina]: U.S. Geol Survey Geol. Atlas, Folio 222, 13 p. Kemp, J. F., 1899, Granites of southern Rhode Island and Connecticut, with observations on Atlantic Coast granites in general: Geol. Soc. America Bull., v. 10, p. 361—382. Kent, L. E., 1939, The geology of a portion of Victoria County, Natal: Geol. Soc. South Africa Trans, v. 41, p. 1—36. Kersten, Charles, 1839, Analyse de la monazite, minéral qui renferme de la thorine et de l’oxide de lantane: Biblio— theque universelle Geneve, new ser., v. 24, p. 185—192. Keystone, 1911, Minerals of South Australia: Keystone, v. 32, no. 5, p. 776. Kiel, H., 1955, Heavy mineral investigation of samples of Sur- inam: Geologic en Mijnbouw, new sen, v. 17, no. 4, p. 93—103. Killeen, P. L., and 0rdway, R. J., 1955, Radioactivity inves- tigations at Ear Mountain, Seward Peninsula, Alaska, 1945: US. Geol. Survey Bull. 1024—0, p. 59—94. Kim, Chong Su, Hwang, In Jon, and Sang, Ki Nam, 1958, Re- port on prospecting of atomic energy mineral resources (2): Korea Geol. Survey Bull. 2, p. 159—188. [In Korean, English summary.] Kimura, Kenjiro, 1925, Analyses of zircon, xenotime and allan— ite of Ishikawa, Iawki Province, Part 4 of The chemical investigations of Japanese minerals containing rarer ele- ments: Japanese Jour. Chemistry Trans. and Abs, v. 2, no. 3, p. 73—79. Kimura, Kenjiro, and Iimori, Takeo, 1936, Monazite, uraninite, and autunite from Japan: Geol. Soc. Japan Jour., v. 43, no. 513, p. 450—452. [In Japanese] 1937, On uraninite, monazite and thucholite from Amaki- mura, Hukuoka Prefecture, Part 26 of Chemical investi- gations of. Japanese minerals containing rarer elements. THE GEOLOGIC OCCURRENCE OF MONAZITE Chem. Soc. Japan Jour., v. 58, no. 11, p. 1135—1143. [In Japanese] Kimura, Kenjiro, and Nakai, Toshio, 1937, Radium contents of uraninite and monazite from Amaki, Hukuoka Prefecture and autunite from Yanai, Yamaguti Prefecture, Part 29 of Chemical investigations of Japanese minerals contain- ing rarer elements: Chem. Soc. Japan Jour., v. 52, no. 12, p. 1257—1260. Kimura, Kenjiro, Okada, Ietake, and Shinoda, Sakae, 1931, On some monazite, ilmenite, inesite, brochantite, corundum, cassiterite, fergusonite, columbite, bismuth, etc. from Japan (Preliminary report 1 and 2): Japanese Assoc. Mineralogists, Petrologists and Econ. Geologists Jour., v. 5, no. 5, p. 211—216; no. 6, p. 269—272. [In Japanese] Kimura, Kenjiro, and Shinoda, Sakae, 1931, Chemical analy- sis of monazite from Jun-an, Korea, Part 16 of Chemical study of oriental rare element minerals: Chem. Soc. Japan Jour., v. 52, no. 1, p. 47—54. [In Japanese] Kimura, Kenjiro, Shinoda, Sakae, and Tanaka, Katsuo, 1935, New localities of zircon, xenotime, monazite, orthite and brookite: Japanese Assoc. Mineralogists, Petrologists and Econ. Geologists Jour., v. 14, no. 3, p. 94—103. [In Japa- nese]. King, B. F., 1932, Mineral composition of sands from Mo- nongahela, Allegheny, and Ohio Rivers: Am. Mineralogist, v. 17, no. 10, p. 485—490. Kirk, H. J. C., 1957, Progress report: British Territories in Borneo, Geol. Survey Dept. Ann. Rept. 1956, p. 56—77. 1958, Geology and mineral resources of the Upper Rajang and adjacent areas: British Territories in Borneo, Geol. Survey Dept. Ann. Rept. 1957, p. 78—79. Kithil, K. L., 1915, Monazite, thorium, and mesothorium: U.S. Bur. Mines Tech. Paper 110, 32 p. Kitson, A. E., 1924a, Report of the Director or the Geological Survey for the period 1st January, 1922 to 31st March, 1923: Gold Coast Geol. Survey Rept. for period January 1922—March 1923, p. 3—54. 1924b, Annual report of the Director, Geological Sur- vey, for the year ended Slst March, 1924: Gold Coast Geol. Survey Rept. for period April 1923—March 1924, p. 3—57. 1927, Report of the Director of the Geological Survey for the year ended 3lst March, 1927: Gold Coast Geol. Survey, Rept. for period April 1926—March 1927, p. 3—92. 19293, Report of the Director of the Geological Survey for the year ended 31st March, 1928: Gold Coast Colony Geol. Survey Rept. for period April 1927—March 1928, p. 3—25. 1929b, Report of the Director of the Geological Survey for the financial year 1928—1929: Gold Coast GeoL Survey Rept. for financial year 1928—1929, p. 3-23. Kitson, A. E., and Felton, W. J., 1930, Minerals of concen- trates from stream-gravels, soils, and crushed rocks of the Gold Coast: Gold Coast Geol. Survey Bull. 6, p. 3—50. Kleeman, A. W., 1940, Schists and gneisses from the moraines, Cape Denison, Adelie Land: Australasian Antartic Ex- ped. 1911—14 Sci. Repts., ser. A, v. 4, pt. 7, p. 197—292. Kline, M. H., and Carlson, E. J., 1954, Pearsol Creek monazite placer area, Valley County, Idaho: US. Atomic Energy Comm. RME—3134, p. 4-23. Kline, M. H., Carlson, E. J., and Griflith, R. H., 1950, Boise Basin monazite placers, Boise County, Idaho: US. Atomic Energy Comm. RME—3129, p. 3—37. BIBLIOGRAPHY Kline, M. H., Carlson, E. J., and Horst, H. W., 1955, Corral Creek monazite placer area, Valley County, Idaho: U.S. Atomic Energy Comm. RME—3135, p. 3—22. Kline, M. H., Carlson, E. J., and Storch, R. H., 1951a, Scott Valley and Horsethief Basin monazite placers, Valley County; Idaho: U.S. Atomic Energy Comm. RME3133, p. 3—22. 1951b, Big Creek monazite placers, Valley County, Idaho: U.S. Atomic Energy Comm. RME—3131, p. 3—24. Kline, M. H., Carlson, E. J., Starch, R. H., and Robertson, A. F., 1953, Bear Valley radioactive mineral placers, Valley County, Idaho: U.S. Atomic Energy Comm. RME—3130, p. 3—23. Kline, M. H., Griffith, R. F., and Hansen, L. A., 1954, Hollow Creek monazite placer, Aiken County, South Carolina: U.S. Atomic Energy Comm. RME—3127, p. 3-29. Koen, G. M., 1955, Heavy minerals as an aid to the correlation of sediments of the Karroo system in the northern part of the Union of South Africa: Geol. Soc. South Africa Trans, v. 58, p. 281-365. Koloniaal Museum Haarlem Bulletin, 1909, Monazit: iaal Mus. Haarlem Bull., no. 42, p. 220—221. Konig, G. A., 1882a, Notes on monazite: Philadelphia Acad. Nat. Sci. Proc., v. 34, p. 15—16. 1882b, Monazite from Virginia: no. 5, p. 423—424. Koto, Bunjiro, 1919, The radioactivity of the monazite from the Junan mine, Korea: Geol. Soc. Tokyo Jour., v. 26, no. 308, p. 230—234. [In Japanese] Kotze, R. N., 1915, Radio-active minerals in South Africa: South African Mining Jour., v. 24, pt. 2, no. 1241, p. 451. Kozu, Shukusuke, and Watanabe, Manjuro, 1926, On the dis- tribution of rare chemical elements in the Japanese is- lands: Pan-Paciflc Sci., Cong, 3d Tokyo, Proc., v. 1, p. 839—852 [1928]. Kremers, H. E., 1958, Commercial thorium ores: Soc. Mining Engineers of Am. Inst. Mining Engineers preprint 5819A18, p. 1-14. Krishnan, M. S., 1951, Mineral resources of Madras: Geol. Survey Mem., v. 80, p. 1-299. 1958, General report of the Geological Survey of India for the year 1954: India Geol. Survey Recs, v. 88, pt. 1, p. 1—356. Kruger, F. 0., 1946, Structure and metamorphism of the Bel- lows Falls quadrangle of New Hampshire and Vermont: Geol. Soc. America Bull., v. 57, no. 2, p. 161—206. Krusch, J. P., 1938, Die metallischen Rohstofle; ihre Lager- ungsverhaltnisse und ihre wirtschaftliche Bedeutung; Heft 2, Molybdan, Monazit, Mesothorium: Stuttgart, Ferdi- nand Enke Verlag, 87 p. Krynine, P. D., 1950, Petrology, stratigraphy, and origin of the Triassic sedimentary rocks of Connecticut: Connecticut Geol. Nat. History Survey Bull. 73, 237 p. Lacroix, Alfred, 1909, Sur l’existence de sables monazites a Madagascar: Soc. francaise minéralogie Bull., v. 33, p. 313—317. 1911, Les minéraux radioactifs de Madagascar: sci. [Paris] Comptes rendus, v. 152, p. 559-564. 1922, Minéralogie de Madagascar, v. 1: Paris, Augustin Challamel, 624 p. 1956, Notes posthumes minéralogie, petrographie Mada- gascar: Madagascar Service Geol. Travaux 78, p. 1—42. Kolon- Am. Naturalist, v. 16, India Acad 311 Ladoo, R. B., 1925, Nonmetallic minerals: New York, Mc- Graw-I—Iill Book 00., 686 p. 1927, Fluorspar, its mining, milling, and utilization with a chapter on cryolite: U.S. Bur. Mines Bull. 244, 185 p. Lafer, Horacio, 1950, Areias monaziticas: Mineragao e Meta- lurgia, v. 14, no. 84, p. 155—160. Lamar, J. E., and Grim, R. E., 1937, Heavy minerals in Illi- nois sands and gravels of various ages: Jour, Sed. Petrology, v. 7, no. 2, p. 78—83. Lamb, F. D., 1955a, Rare earth metals: v. 156, no. 2, p. 106. 1955b, Rare-earth metals—A chapter from mineral facts and problems: U.S. Bur. Mines Bull. 556, p. 1—9 (pre- print). Lamb, F. D., North, 0. S., Chandler, H. P., and Arundale, J. C., 1953, Minor nonmetals: U.S. Bur. Mines Minerals Year- book, 1950, p. 1343—1362. Lamcke, Kurt, 1937, Natiirliche Anreicherungen von Schwer- mineralien in Kiistengebieten: Geologie der Meere u. Binnengewiisser, v. 1, p. 106—125. 1940, Natiirliche Anreicherungen von Schwermineralien in Kiistengebieten. (2): Geologic der Meere u. Binnenge- wasser, v. 4, no. 1, p. 77—92. Landes, K. K., 1932, The Baringer Hill, Texas, pegmatite: Am. Mineralogist, v. 17, no. 8, p. 381—390. Landsberg, Helmut, and Klepper, M. R., 1939a, Radioactivity tests of rock samples for the correlation of sedimentary horizons: Am. Inst. Mining Metall. Engineers Tech. Pub. 1103, p. 1—9. 1939b, Measurements of radioactivity for stratigraphic studies: Am. Geophys. Union Trans, v. 20, pt. 3, p. 277— 280. Lane, A. 0., 1932, Report of the Committee on the Measure- ment of Geologic Time: Natl. Research Council, Div. Geology and Geography, p. 1—73. 1934, Report of the Committee on the Measurement 01' Geologic Time: Natl. Research Council, Div. Geology and Geography, p. 1—86. 1935, Report of the Committee on the Measurement of Geologic Time: Natl. Research Council, Div. Geology and Geography, p. 1—85. 1936, Report of the Committee on the Measurement of Geologic Time: Natl. Research Council, Div. Geology and Geography, p. 1—87. 1937, Report of the Committee on the Measurement of Geologic Time: Natl. Research Council, Div. Geology and Geography, p. 1—77. 1938a, Report of the Committee on the Measurement of Geologic Time: Natl. Research Council, Div. Geology and Geography, p. 1—125. 1938b, Radioactive methods of determining the age of minerals and rocks: Canadian Mining Metall. Bull., no. 310, p. 130—132. Laney, F. B., and Wood, K. H., 1909, Bibliography of North Carolina geology, mineralogy and geography: North Caro- lina Geol. Survey Bull. 18, 428 p. Lang, A. H., 1952, Canadian deposits of uranium and thorium (interim account): Canada Geol. Survey Econ. Geology Sen, no. 16, p. 1—173. Lang, W. B., King, P. B., Bramlette, M. N., McVay, T. N., Bay, H. X., and Munyan, A. C., 1940, Clay investigations in the southern states 1934—35: U.S. Geol. Survey Bull. 901, 346 p. Eng. Mining Jour., 312 Larsen, E. S., and Keevil, N. B., 1947, Radioactivity of the rocks of the batholith of southern California: Geol. Soc. American Bull., v. 58, no. 6, p. 483—494. Larsen, E. S., Jr., Keevil, N. B., and Harrison, H. C., 1952, Method for determining the age of igneous rocks using the accessory minerals: Geol. Soc. America Bull., v. 63, p. 1045-1052. LaTouche, T. H. D., 1918, A bibliography of Indian geology and physical geography with/an annotated index of min- erals of economic value, pt. 2: Calcutta, India Geol. Sur- vey, 490 p. Leao, Josias, 1939, Mines and minerals in Brazil: Rio de Janeiro, Centro de Estudos Economicos, 243 p. Lebedeif, V., 1935, Résumé des résultats d’une mission de recherches géologiques et miniéres en Guyane frangaise: Chronique mines coloniales, v. 4, no. 45, p. 394—408. Lecoq, J. J., 1957, Une perspective miniere nouvelle a Mada- gascar les sables a monazite: Echo mines et métallurgie, no. 3509, p. 591—594. Lee, Dai Sung, Lee, Chong Hwa, and Yun, Sang Kyi, 1956, Report on the search for radioactive-mineral resources (I): Korea Geol. Survey Bull. 1, p. 48-68. [In Korean, English title.] Lefforge, J. W., Haseman, J. F., Courtney, A. L., and Rice, W. A., 1944, Monazite gravels of the Carolinas; analyses and concentration tests: Tennessee Valley Authority Rept. 496 [unnumbered pages]. Lemke, R. W., Jahns, R. H., and Griflitts, W. B., 1952, Part 2 of Mica deposits of the southeastern Piedmont, Amelia district, Virginia: U.S. Geol. Survey Prof. Paper 248—B, p. 103—139. Lenhart, W. B., 1956, Rare mineral recovery is the main business: Rock Products, v. 59, no. 9, p. 62—69. Leonardos, O. H., 1936a, Uma jazida de berylio, mica, colum- bita, annerodita e monazita, em Sabinopolis, Minas Geraes: Mineracfio e Metalurgia, v. 1, no. 1, p. 15-16. 1936b, Tantalo, niobio, uranio e radio no Brasil: Brasil Servico Fomento Producgao Mineral B01. 11, p. 3—56. 1937a, Monazita no estado da Bahia: Brasil Servico Fomento Produccao Mineral Rept. 23, 17 p. 1937b, Monazita no estado da Baia: Cong. Sui-Ameri- cano de Quimica, 3th, Rio de Janeiro, 8th sess., v. 7, p. 553-573. 1950, Devemos industrializar no Brasil 0s minérios de metals raros: Mineragao e Metalurgia, v. 14, no. 83, p. 137—140. Lévy, A., 1823, Description of a new mineral: Annals Philoso- phy, new sen, v. 5, p. 241—243, London. Levy, S. I., 1924a, Monazite in the Dutch East Indies: Chem. Trade J our. and Chem. Engineer, v. 75, no. 1951, p. 430. 1924b, The rare earths, their occurrence, chemistry, and technology [2d ed.]: New York, Longmans, Green, and 00., 362 p. Lewis, W. E., 1959, Rare-earth minerals and metals: U.S. Bur. Mines Minerals Yearbook, 1958, v. 1, p. 1—6 (pre- print). 1960, Rare-earth minerals and metals: U.S. Bur. Mines Minerals Yearbook, 1959, v. 1, p. 895—900. Liddell, D. M., 1917, A Florida rare-mineral deposit: Eng. Mining Jour., v. 104, no. 4, p. 153—155. THE GEOLOGIC -OCCURRENCE OF MONAZITE Liebenberg, W. B., 1955, The occurrence and origin of gold and radioactive minerals in the Witwatersrand system, the Dominion Reef, the Ventersdorp Contact Reef and the Black Reef: Geol. Soc. South Africa Trans, v. 58, p. 101—254. Lincoln, F. C., 1923, Mining districts and mineral resources of Nevada: Reno, Nevada Newsletter Pub. 00., 295 p. Lindgren, Waldemar, 1897, Monazite from Idaho: Am. Jour. Sci., 4th ser., no. 19, p. 63—64. 1898, The mining districts of the Idaho Basin and the Boise Ridge, Idaho: U.S. Geol. Survey 18th Ann. Rept., pt. 3, p. 617—736. Lisbfia, J. M. A., 1950, As areias monaziticas: Ouro Préto Escola de Minas Rev., v. 15, no. 2, p. 16, 27—36. Lleras Codazzi, B., 1916, Contribucién a1 estudio de los min- erales de Colombia: Bogota, Imprenta de La Repfiblica, p. 3—22. 1927, Los minerales de Colombia: Bogota, Biblioteca Mus. Nac., 150 p. Lombard, Jean, 1955, Caractéres généraux des occurrences de carbonatites. Minéraux associés: Chronique mines colo- niales, v. 23, no. 234, p. 310-316. Lortie, L., 1943, The rare earths, their history and occurrence, properties and applications: South African Mining and Eng. Jour., v. 54, pt. 1, no. 2634, p. 447, 457. Loughlin, G. F., 1912, The gabbros and associated rocks at Preston, Connecticut: U.S. Geol. Survey Bull. 492, 158 p. Lovering, T. G., 1954, Radioactive deposits of Nevada: U.S. Geol. Survey Bull. 1009—0, p. 63—106. Low, Hugh, 1848, Sarawak; its inhabitants and productions: being notes during a residence in that country with H. H. the Rajah Brooke: London, Richard Bentley, p. 1—416. Lyden, C. J., 1948, The Gold placers of Montana: Montana Bur. Mines and Geology Mem. 26, p. 1—152. Lyons, J. B., Jafie, H. W., Gottfried, David, and Waring, C. L., 1957, Lead—alpha ages of some New Hampshire gran— ites: Am. Jour. Sci., v. 255, no. 8, p. 527—546. McCauley, C. K., 1960, Exploration for heavy minerals on Hil- ton Head Island, S.C.: South Carolina State Devel. Board Div. Geology, Geologic Notes, v. 4, no. 4, p. 1—34. MacConachie, H., 1957a, Mining rare metals in the Namaqua- land desert: Optima, v. 7, no. 2, p. 95—100. 1957b, Mining rare metals in Namaqualand: Mining Jour. [London], v. 249, no. 6372, p. 394—395. McDaniel, W. T., 1943, The monazite deposits of the Carolinas: Tennessee Valley Authority open—file pub., p. 1—16. MacDonald, A. R., 1906, Report of the Department of Mines, Queensland, for the year 1905: Queensland Dept. Mines Ann. Rept. of Under Secretary for Mines, 1905, p. 1—166. 1912, Report of the Department of Mines, Queensland, for the year 1911: Queensland Dept. Mines Ann. Rept. of Under Secretary for Mines, 1911, p. 1—207. Mackay, R. A., Greenwood, R., and Rockingham, J. E., 1949, The geology of the Plateau tinfields—resurvey 1945—48: Nigeria Geol. Survey Bull. 19, 80 p. McKelvey, V. E., 1955, Search for uranium in the United States: U.S. Geol. Survey Bull. 1030—A, p. 1—64. McKeown, F. A., 1961, Reconnaissance of radioactive rocks of Vermont, New Hampshire, Connecticut, Rhode Island and southeastern New York: U.S. Geol. Survey TEI—67, 46 p., issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. BIBLIOGRAPHY McKeown, F. A., 1954, Northeast district in Geologic investiga- tions of radioactive deposits—Semia-nnual progress report, December 1, 1953 to May 31, 1954: U.S. Geol. Survey TEI— 440, p. 166—167 issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. McKeown, F. A., and Klemic, Harry, 1953, Reconnaissance for radioactive materials in northeastern United States dur- ing 1952: U.S. Geol. Survey TEI—317—A, 68 p., issued by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. 1965, Rare-earth-bearing apatite at Mineville, Essex County, New York: U.S. Geol. Survey Bull. 1046—B, p. 9—23. Mackin, J. E., and Schimdt, D. L., 1956, Uranium- and tho- rium—bearing minerals in placer deposits in Idaho, in Page, L. R., Stocking, H. E., and Smith, H. B., 1956, Contribu- tions to the geology of uranium and thorium by the United States Geological Survey and Atomic Energy Commission for the United Nations International Conference on Peace- ful Uses of Atomic Energy, Geneva, Switzerland, 1955: U.S. Geol. Survey Prof. Paper 300, p. 375—380. 1957, Uranium and thorium-bearing minerals in placer deposits in Idaho: Idaho Bur. Mines and Geology Mineral Resources Rept. 7, p. 1-8. McKie, Duncan, 1957, A synopsis of mineral paragenesis in the complex pegmatites of Tanganyika: Comm. Tech. Co-op. in Africa South of the Sahara, Comités régionaux Centre, Est et Sud, Conf. de Tananarive April 1957, Geologic v. 1, p. 159—172. Mckinney, A. A., and Horst, H. W., 1953, Deadwood conglom- erate monazite, Bald Mountain area, Sheridan and Big Horn Counties, Wyoming: U.S. Atomic Energy Comm. RME—3128, p. 3—39. MacLaurin, J. S., 1912, Rocks, minerals, and ores: New Zea- land Dominion Lab. Ann. Rept., v. 45, p. 21—24. 1913, Rocks, minerals, and ores: New Zealand Domin- ion Lab. Ann. Rept., v. 46, p. 21—26. McMaster, R. L., 1954, Petrography and genesis of the New Jersey beach sands: New Jersey Bur. Geology and Topo- graphy Bull. 63, p. 1—239. McMillan, A., 1918, Burmese monazite sands: Indus. and Eng. Chemistry Jour. v. 10, no. 12, p. 1020. McNaughton, J. H. M., 1958a, Radioactive mineral prospecting: Nyasaland Protectorate Geol. Survey Dept. Ann. Rept. 1957, p. 26—27. 1958b, Notes on economic minerals: Nyasaland Pro- tectorate Geol. Survey Dept. Ann. Rept., 1957, p. 28—31. 1959, Radioactive mineral prospecting: Nyasaland Pro- tectorate Geol. Survey Dept. Ann. Rept. for year ended 31st December 1958, p. 47. Macpherson, E. 0., 1938, Round Hill goldfield, Southland: New Zealand Jour. Sci. and Technology, v. 19, no. 12, p. 743— 749. Madagascar Direction des Mines, 1924, Exportations minieres de Madagascar: Mines Madagascar Bull., no. 21, p. 139. Mahadevan, 0., and Rao, R. N., 1950, Black sand concentrates of Vizagapatam coast: Current Sci. [Bangalore], v. 19, no. 2, p. 48—49. Mahadevan, C., and Sathapathi, N., 1948, The home of mona- zite in the Vizagapatam area: Current Sci. [Bangalore], v. 17, no. 10, p. 297. 238—813—67———21 313 Mair, J. A., Maynes, A. D., Patchett, J. E., and Russell, R. D., 1960, Isotopic evidence on the origin and age of the Blind River uranium deposits: Jour. Geophys. Research, v. 65, no. 1, p. 341—348. Maitland, A. G., 1904, Miscellaneous mineral notes: Western Australia Geol. Survey Ann. Prog. Rept. for 1903, p. 26. Mallet, J. W., 1882, Notes on work by students of practical chemistry in the laboratory of the University of Virginia (11) : Chem. News [London], v. 46, no. 1197, p. 204-206. Manchester, J. G., 1931, The minerals of New York City and its environs: New York Mineralog. Club Bull., v. 3, no. 1, p. 7—168. Marble, J. P., 1936, Possible age of monazite from Mars Hill, North Carolina: Am. Mineralogist, v. 21, no. 7, p. 456— 457. 1948, Report of the Committee on the Measurement of Geologic Time, 1946—1947: Nat. Research Council, Div. of Geology and Geography, p. 1—69. 1949a, Report of the Committee on the Measurement of Geologic Time, 1947—1948: Nat. Research Council, Div. of Geology and Geography, p. 1—77. 1949b, Report of the Committee on the Measurement of Geologic Time, 1948—1949: Nat. Research Council, Div. of Geology and Geography, p. 1—139. Markewicz, F. J., Chao, E. T. C., and Milton, Charles, 1957, Radioactive minerals of New Jersey [abs]: Geol. Soc. America Bull., v. 68, no. 12, pt. 2, p. 1763. Markewicz, F. J., and Parrillo, D. G., 1957, Preliminary re- port on the ilmenite—bearing sands from the coastal plain of New Jersey [abs]: Geol. Soc. America Bull., v. 68, no. 12, pt. 2, p 1763. Markewicz, F. J., Parrillo, D. G., and Johnson, M. E., 1958, The titanium sands of southern New Jersey: Soc. Min- ing Engineers of Am. Inst. Mining Engineers preprint 5818A5, p. 1—10. Marshall, P., 1908, Additions to the list of New Zealand min- erals: New Zealand Inst. Trans, v. 41, p. 105—110. Martens, J. H. C., 1928, Beach deposits of ilmenite, zircon, and rutile in Florida: Florida Geol. Survey 19th Ann. Rept., p. 124—154. 1929, The mineral composition of some sands from Que- bec, Labrador and Greenland: Field Mus. Nat. Hist, Geology ser., v. 5, no. 2, p. 17—31. 1932, Mineralogy of sandstones of northern West Vir- ginia: West Virginia Acad. Sci. Proc., v. 6, p. 72—80 [1933]. 1935, Beach sands between Charleston, South Carolina, and Miami, Florida: Geol. Soc. America Bull., v. 46, p. 1563—1596. 1939, Petrography and correlation of deep-well sec- tions in West Virginia and adjacent states: West Vir- ginia Geol. Survey Repts., v. 11, p. 1—255. Masillamani, E., and Chacko, I. C., 1913, Monazite: Imp. Inst. [London] Bull., v. 11, no. 4, p. 699—700. Masutomi, J., 1944, Zircon, monazite, and anatase from Hase- machi, Naraken [abs]: Japanese Assoc. Mineralogists, Petrologists and Econ. Geologists, v. 31, no. 5, p. 42—43. [In Japanese] Matthew, W. D., 1895, Monazite and orthoclase from South Lyme, Conn.: Columbia Univ. School Mines Quart, v. 16, no. 3, p. 231—233. Matthews, A. F., 1948, Uranium and thorium: U.S. Bur. Mines Minerals Yearbook, 1946, p. 1205—1231. 314 Matthews, P. F. P., 1953, Part of the Kanuku Mountains east of the Rupununi River, in Pollard, E. B., Report on the Geological Survey Department for the year 1952: British Guiana Geol. Survey Dept. Rept., p. 79—89. Mattos Netto, B. C. de, 1951, Combustiveis nucleares: Engen- haria, Mineragao e Metalurgia, v. 15, no. 89, p. 185—187. Matveyeff, Const., 1932, Einige data iiber die R6ntgenspek— troskopie der Monazite von der Bortschowotschny-Kette, Transbaikalien: Neues Jahrb. Mineralogie, Geologic u. Paliiontologie, Beilage-Band 65, Abt. A, p. 223—232. Mawson, Douglas, 1906, On certain new mineral species as- sociated with carnotite in the radio-active ore body near Olary: Royal Soc. South Australia Trans. and Proc., v. 30, p. 188—193. 1916, Mineral notes: Royal Soc. South Australia Trans. and Proc., v. 40, p. 262—266. 1923, Igneous rocks of the Mount Painter belt: Royal Soc. South Australia Trans. and Proc., v. 47, p. 376—387. 1940, Record of minerals of King George Land, Adelie Land and Queen Mary Land: Australasian Antarctic Exped. 1911—14 Sci. Repts., ser. A, v. 4, pt. 12, p. 371—404. Mawson, Douglas, and Laby, T. H., 1904, Preliminary observa- tions on radio-activity and the occurrence of radium in Australian minerals: Royal Soc. New South Wales Jour. and Proc., v. 38, p. 382—389. Meisner, Max, 1929, Seltene Grundstoife Radium und Uran, Thorium, Zerium usw. (Uranerze und Monazit): Preuss. Geol. Landesanst., Weltmontanstatistik, v. 1, pt. 2, p. 225—236. Melhase, John, 1936, A new occurrence of rare-earth minerals in California: Mineralogist, v. 4, no. 1, p. 11. Memminger, Lucien, 1917a, Reported discovery of monazite in Mysore: U.S. Bur. Foreign and Domestic Commerce, Com- merce Repts., v. 208, p. 894. 1917b, Unfavorable report on Mysore monazite: U.S. Bur. Foreign and Domestic Commerce, Commerce Repts., no. 271, p. 681. Mendelssohn, E., and Marland, E. F., 1933, An occurrence of monazite in the Sub Nigel mine, Witwatersrand: Geol. Soc. South Africa Trans, v. 36, p. 113—115. Merensky, Hans, 1908, The rocks belonging to the area of the Bushveld granite complex, in which tin may be expected, with descriptions of deposits actually found: Geol. Soc. South Africa Trans, v. 11, p. 25—42. Mertie, J. B., Jr., 1925, Geology and gold placers of the Chandalar district, Alaska: U.S. Geol. Survey Bull. 773— E, p. 215—263. 1949, Monazite, in Industrial minerals and rocks [2d ed.] : New York, Am. Inst. Mining Metall. Engineers, p. 629— 636. 1953, Monazite deposits of the southeastern Atlantic States: U.S. Geol. Survey Circ. 237, 31 p. 1955, Ancient monazite placer [abs.]: Geol. Soc. Am- erica Bull., v. 66, no. 12, pt. 2, p. 1692-1693. 1956, Paragneissic formations of northern Virginia [abs.]: Geol. Soc. America Bull., v. 67, no. 12, pt. 2, p. 1754—1755. 1957, Geologic occurrence of monazite and xenotime in the southeastern states [abs.]: Geol. Soc. America Bull., v. 68, no. 12, pt. 2, p. 1766-1767. 1958, Zirconium and hafnium in the southeastern At- lantic states: U.S. Geol. Survey Bull. 1082—A, 28 p. Messner, W. E., 1955, Scrubbing solves sand flotation prob- lem: Mining Eng. [New York], v. 7, no. 2, p. 138-139. THE GEOLOGIC OCCURRENCE OF MONAZITE Metal Industry, 1917, Monazite: p. 5. Metallurgical and Chemical Engineering, 1910, Monazite in Idaho: Metall. and Chem. Eng, v. 8, no. 12, p. 655. 1915, Analysis of Brazilian monazite sand: Metall. and Chem. Eng., v. 13, no. 6, p. 403. Metallurgie und Erz, 1916, Monazitsandlager: Metallurgie u. Erz, v. 13, no. 15, p. 348. 1924, Niederlande—Indien: Metallurgie u. Erz, v. 21, no. 14, p. 347. Meuschke, J. L., 1955, Airborne radioactivity survey of the Edisto Island area, Berkeley, Charleston, Colleton, and Dorchester Counties, South Carolina: U.S. Geol. Survey Geophys. Inv. Map GP~123. Meuschke, J. L., Moxham, R. M., and Bortner, T. E., 1953, Airborne radioactivity survey of part- of the Atlantic Ocean beach, North and South Carolina: U.S. Geol. Survey TEM—673, open-file map. Mezger, C. A., 1895, The monazite districts of North and South Carolina: Am. Inst. Mining Engineers Trans, v. 25, p. 822—826, 1036—1040 [1896]. 1896, The monazite districts of North and South Caro- lina: Mining Jour. [London], v. 66, no. 3168, p. 583. Middelberg, E., 1908, Geologische en technische aanteekeningen over de goudindustrie in Suriname: Amsterdam, J. H. de Bussy, 132 p. Miller, R. B., 1939, Mineral resources of Germany’s former colonial possessions: U.S. Bur. Mines Foreign Minerals Quart, v. 2, no. 3, p. 2—13. Miller, Roswell, III, 1945, The heavy minerals of Florida beach and dune sands: Am. Mineralogist, v. 30, nos. 1— 2, p. 65—75. Millington, W. M., 1928, Annual report of the British Adviser, Trengganu for the year 1927; Great Britain Colonial Oflice, Colonial Repts., Ann. Ser. 1415, p. 1—23. Minami, Yen-ichi, 1929, Analysis of allanite from Hagata- Mura, Iyo Province: Japanese Jour. Chemistry Trans. and Abs., v. 4, no. 1, p. 1—5. Miner, F. L., 1929, Rare elements disclosed in gold deposit of California mine: Mining Rev., v. 31, no. 7, p. 9. Mineral Collector, 1908, New York City minerals: Collector, v. 15, no. 6, p. 87—90. Mines Magazine, 1957, Titanium minerals on Amelia Island: Mines Mag, v. 47, no. 5, p. 45. Mineralogist, 1950, Rare earths found: no. 10, p. 459. Mingaye, J. C. H., 1903, Notes on the occurrence of monazite in the beach sands of the Richmond River, New South Wales: New South Wales Geol. Survey Recs, v. 7, pt. 3, p. 222—226. 1909, Notes from the chemical laboratory (2) : Experi- ments on the estimation of thoria in monazite: New South Wales Geol. Survey Recs, v. 8, pt. 4, p. 276—286. Mining and Engineering Review, 1911, Australasia and the Anarctic: Mining and Eng. [Melbourne] Rev., v. 3, p. 191—192. Mining and Scientific Press, 1902, Production of rare minerals: Mining and Sci. Press, v. 84, no. 21, whole no. 2183, p. 281. Mining Congress Journal, 1948, Separation of monazite sands: Mining Cong. Jour., v. 34, no. 7, p. 70. 1949, Monazite production: Mining Cong. Jour., v. 35, no. 7, p. 71. Metal Industry, v. 10, no. 27, Mineral Mineralogist, v. 18, BIBLIOGRAPHY Mining Engineering, 1951, Monazite sands from which thorium is extracted: Mining Eng, [New York], v. 3, no. 6, sec. 1, p. 488. Mining Journal, 1894, Monazite mining in North Carolina: Mining Jour. [London], V. 64, no. 3087, p. 1148. 1903a, Mining in New South Wales: Mining Jour. [London], v. 73, no. 3521, p. 181—182. 1903b, Monazitic sand in Brazil: Mining Jour. [Lon- don], v. 73, no. 3536, p. 644. 1903c, Monazite sands in Brazil: don], v. 73, no. 3518, p. 103. 1906, Monazite tin ore in Federated Malay States: Min- ing Jour. [London], v. 80, no. 1713, p. 475. 1908, Northern Territory, thorium: Mining Jour., [Lon- don], V. 84, no. 3802, p. 7. 1909, South Australia monazite: V. 86, no. 3854, p. 5. 1911, Monazite discovery in southern India: Jour. [London], v. 94, no. 3960, p. 740. 1914, New sources of monazite: Mining Jour. [Lon- don], V. 104, no. 4096, p. 194. 1915, Monazite in southern Somaliland: [London], v. 111, no. 4184, p. 759. 1925a, Monazite in Orissa: Mining Jour. v. 150, no. 4691, p. 576. 1925b, Rare-element minerals in Canada: [London], v. 149, no. 4679, p. 333. 1930, Helium from Ceylon monazite: [London], V. 171, no. 4970, p. 913. 1941a, Tasmania: Mining Jour. [London], V. 214, no. 5535, p. 428. 1941b, Tasmania: 5543, p. 50. 1942, Graphite and monazite in Brazil: [London], V. 217, no. 5574, p. 294. 1945, Ceylon’s graphite deposits: don], v. 224, no. 5716, p. 156. 1947a, Ceylon and India: v. 229, no. 5844, p. 526. 1947b, Uranium and thorium deposits: [London], v. 228, no. 5836, p. 379. 1949, Mineral prospecting in Mogambique: Jour. [London], v. 232, no. 5919, p. 79. 1953, Namaqualand’s mineral wealth: [London], V. 241, no. 6175, p. 751—752. 1954a, The mining and treatment of rare earths: Min- ing J our. [London], v. 243,’ no. 6205, p. 96—97. 1954b, Mining and treatment of rare earths in Aus- tralia: Mining Jour. [London], v. 243, no. 6206, p. 130— 131. Mining Journal [Phoenix], 1938, Western Gold Corporation has extensive holdings: Mining Jour. [Phoenix], v. 21, no. 17, p. 34. Mining Magazine, 1956, Cape York Peninsula: [London], V. 95, no. 5, p. 289—290. Mining Science, 1910, Monazite in Idaho: no. 1603, p. 365. Mining World, 1949, Thorium found in Mississippi: World, V. 11, no. 10, p. 74. 1952, Argentina: Mining World, v. 14, no. 9, p. 78. 1954, Union Carbide exploring Mozambique and Nyasa- land: Mining World, v. 16, no. 4, p. 56. Mining Jour. [Lon- Mining J our. [London], Mining Mining J our. [London], Mining J our. Mining J our. Mining Jour. [London], V. 215, no. Mining J our. Mining Jour. [Lon- Mining Jour. [London]. Mining J our. Mining Mining J our. Mining Mag. Mining Sci., V. 62, Mining 315 Mining World. 1955, Lindsay Chemical options Canadian mona- zite lode: Mining World, V. 17, no. 13, p. 77. 1956, British Guiana: Mining World, V. 18, no. 4, p. 68. 1957a, Nyasaland: Mining World, V. 19, no. 5, p. 122. . 1957b, South West Africa: Mining World, V. 19, no. 6, p. 97. 19570, Amelia Island, Fla.: p. 35. 1958, Manitoba: Mining World, v. 20, no. 3, p. 96. 1959, India: Mining World, v. 21, no. 8, p. 84—85. Miranda, José, 1943, Areias ilmeniticas no Brasil: Miner- agao e Metalurgia, v. 7, no. 40, p. 195—198. Molloy, M. W., 1959, A comparative study of ten monazites: Am. Mineralogist, v. 44, nos. 5—6, p. 510—532. Moore, B. N., 1937, Nonmetallic mineral resources of eastern Oregon: U.S. Geol. Survey Bull. 875, 180 p. Moore, R. T., 1953, Minerals and metals of increasing inter- est, rare and radioactive minerals: Arizona Univ. Bull., v. 24, no. 4, Arizona Bur. Mines Mineral Tech. Ser. 47. Bull. 163, p. 5-40. Moraes, L. J. de, 1937, Areia monazitica nos estados do Es- pirito Santo e Rio de Janeiro: Brasil Ministério ag- ricultura Divisao de fomento de produccao mineral Bol., v. 26, nos. 4—6, p. 67—73. 1956, Known occurrences of uranium and thorium in Brazil: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 134—139. Moraes, L. J. de, Barbosa, Octavio, Lisboa, J. M., Arrojado and Lacourt, Fernando, 1937, Recursos mineraes, in Moraes, L. J. de, and others, Geologia economica do norte de Minas Geraes: Brasil Servigo Fomento Produccfio Mineral B01. 19, p. 131—132. Moraes, L. J. de, and Guimaraes, Djalma, 1931, The diamond- Mining World, v. 19, no. 7, bearing region of northern Minas Geraes, Brazil: Econ. Geology, v. 26, no. 5, p. 502—530. Moraes, L. J. de, Leonardos, Othon, and Lisboa, Moacyr, 1937, Areia monazitica no Brazil: Cong. Sul-Americano de Quimica, 3th, Rio de Janiero, 8th sess., V. 7, p. 545—552. Moravia, E. M., J r., 1909, Monasita, deposito, extracgao e trata- mento: Ouro PretoEscola Minas Annaes, no. 11, p. 37—44. Morgan, P. G., 1911, The geology of the Greymouth Subdivi- sion, North Westland: New Zealand Dept. Mines, Geol. Survey Branch Bull. 13, new ser., p. 1—159. 1913, Field-work in the Buller-Mokihinui Subdivision: New Zealand Geol. Survey 7th Ann. Rept, p. 117—119. 1927, Minerals and mineral substances of New Zealand: New Zealand Geol. Survey Bull. 32, new ser., p. 1—110. Morgan, P. G., and Bartrum, J. A., 1913, List of the minerals of New Zealand: New Zealand Geol. Survey Bull. p. 3—32. 1915, The geology and mineral resources of the Buller— Mokihinui Subdivision, Westport Division: New Zea- land Geol. Survey Bull. 17 new ser., p. 1—210. Morrill, Philip, 1958, Western Maine, Volume 1 of Maine mines and minerals: Naples, Maine, Dillingham Nat. His- tory Mus. p. 1—80. 1959, Eastern Maine, Volume 2 of Maine mines and minerals: Naples, Maine, Dillingham Nat. History Mus., p. 1—80. 1960, New Hampshire mines and mineral localities [2d ed.]: Hanover, N. H., Dartmouth College Mus., 46 p. Moxham, R. M., 1954a, Reconnaissance for radioactive de- posits in the Manley Hot Springs-Rampart District, east- central Alaska, 1948: U.S. Geol. Survey Circ. 317, p. 1—6. 316 Moxham, R. M., 1954b, Airborne radioactivity survey in the Folkston area, Charlton County, Georgia, and Nassau County, Florida: U.S. Geol. Survey Geophys. Inv. Map GP—119. Moxham, R. M., and Johnson, R. W., 1953: Airborne radio- activity survey of parts of the Atlantic Ocean beach, Virginia to Florida: U.S. Geol. Survey TEM-644, open- file map. Moxham, R. M., Walker, G. W., and Baumgardner, L. H., 1955, Geologic and airborne radioactivity studies in the Rock Corral area, San Bernardino County, California: U.S. Geol. Survey Bull. 1021—C, p. 109—125. Muench, O. B., 1938a, “Glorieta” monazite: J our., v. 60, no. 11, p. 2661—2662. 1938b, Glorieta monazite [abs]: ogist, v. 70, no. 1, p. 73. 1950, Recent analyses for age by lead ratios: Soc. America Bull., v. 61, no. 2, p. 129—132. Mulligan, J. J., and Thorne, R. L., 1959, Tin-placer sampling methods and results, Cape Mountain district, Seward Peninsula, Alaska: U.S. Bur. Mines Inf. Circ. 7878, p. 1— 69. Murata, K. J., and Bastron, Harry, 1956, A convenient method for recognizing nonopaque cerium earth minerals: Sci- ence, v. 123, no. 3203, p. 888—889. Murata, K. J., Dutra, C. V., Costa, M. Teixeira da, and Branco, J. J. R., 1958. Composition of monazites from pegmatites in eastern Minas Gerais, Brazil: Geochim. et Cosmo- chim. Acta, v. 16, p. 1—14. Murata, K. J., Rose, H. J., Jr., and Carron, M. K., 1953, Sys- tematic variation of rare earths in monazite: Geochim. et Cosmochim. Acta, v. 4, p. 292—300. Murata, K. J., Rose, H. J., Jr., Carron, M. K., and Glass, J. J., 1957, Systematic variation of rare—earth elements in ceri- um-earth minerals: Geochim. et Cosmochim. Acta, v. 11, p. 141—161. Murdoch, Joseph, and Webb, R. W., 1948, Minerals of Cali- fornia: California Div. Mines Bull. 136, p. 3—402. 1956, Minerals of California: California Div. Mines Bull. 173, p. 3—452. Murphy, J. F., and Houston, R. S., 1955, Titanium-bearing black sand deposits of Wyoming in Wyoming Geol. Assoc. Guidebook, 10th Ann. Field Conf. Green River Basin, 1955: p. 190—196. Murray, E. G., and Adams, J. A. S., 1958, Thorium, uranium and potassium in some sandstones: Geochim. et Cosmo- chim. Acta, v. 13, no. 4, p. 260—269. Murray-Hughes, Robert, 1933, The Loldaika—Ngare Ndare area: Kenya Geol. Survey Rept. 1, p. 1—5. Nag, B. D., Das, Sudhansu, and Dasgupta, Arun, 1944, In- vestigations on the radioactive contents of certain In- dian minerals: India Nat. Inst. Sci. Proc., v. 10, no. 2, p» 167—174. Nair, R. V., and Moosath, S. S., 1955, Studies on monazite sand, I. Separation of the phosphatic content: Travan- core Univ. Central Research Inst. Bull., ser. A, v. 4, no. 1, p. 63—68. Nakhla, F. M., 1958, Mineralogy of the Egyptian black sands and its applications: Egyptian Jour. Geol., v. 2, no. 1, p. 1—22. Nederlandsch-Indié, Dienst van den Mijnbouw, 1935, Jaarboek van het Mijnwezen in Nederlandsch-Indié: Nederlandsch- Indi'e, Dienst van den Mijnbouw, V. 61, p. 1—210. Am. Chem. Soc. Pan-American Geol- Geol. THE GEOLOGIC OCCURRENCE OF MONAZITE 1938, Productiestatistieken van de Voornamste Delf- stofien in Nederlandsche-Indié over Dejaren 1935—1936: Jaarb. Mijnwezen Nederlandsche-Indié, v. 65—66. p. 334. Neiheisel, James, 1958a, Heavy mineral beach placers of the South Carolina coast: South Carolina Devel. Board, Div. Geology, Mineral Industries Lab. Monthly Bull., v. 2, no. 1, p. 1—7. 1958b, Origin of the dune system on the Isle of Palms, South Carolina: South Carolina Devel. Board, Div. Geol., Mineral Industries Lab. Monthly Bull., v. 2, no. 7, p. 46—51. 1962, Heavy-mineral investigation of Recent and Pleis— tocene sands of lower Coastal Plain of Georgia: Geol. Soc. America Bull., v. 73, no. 3, p. 365—374. Nelson, A. E., 1953, Koyukuk-Chandalar region, in Wedow, Helmuth, Jr., and others, Preliminary summary of re— connaissance for uranium and thorium in Alaska, 1952: U.S. Geol. Survey Circ. 248, p. 3—4. Nelson, A. E., West, W. S., and Matzko, J. J ., 1954, Reconnais- sance for radioactive deposits in eastern Alaska, 1952: U.S. Geol. Survey Circ. 348, 21 p. Netherlands Engineering Consultants, 1959, River studies and recommendations on improvement of Niger and Benue: Amsterdam, North Holland Pub. 00., 1000 p. New Zealand Mines Record, 1903, Monazite sand: land Mines Rec., v. 7, no. 3, p. 128—130. 1905, [Monazite from the River Parahyba] : New Zealand Mines Rec., v. 9, no. 5, p. 212. 1906, Notes and comment: New Zealand Mines Rec., v. 9, n0. 9, p. 398—404. Niino, Hiroshi, and Emery, K. 0., 1961, Sediments of shal- low portions of East China Sea and South China Sea: Geol. Soc. America Bull., v. 72, no. 5, p. 731—762. New Zea- Nininger, R. D., 1954, Minerals for atomic energy: New York, D. Van Nostrand Co., 367 p. 1956, Minerals for atomic energy [2d ed.]: Princeton, New Jersey, D. Van Nostrand Co., 399 p. Nitze, H. B. C., 18953, Monazite: U.S. Geol. Survey 16th Ann. Rept., pt. 4, p. 667—693. 1895b, Monazite and monazite deposits in North Caro- lina: North Carolina Geol. Survey Bull. 9, p. 1—47. ‘ 1895c, North Carolina monazite: Chem. News, v. 71, no. 1846, p. 181. 1897, Monazite: p. 127—133. Niven, William, 1895, On a new locality for xenotime, mona- zite, etc., on Manhattan Island: Am. Jour. Sci., 3d sen, v. 50, no. 295, p. 75. Nordenskiiild, A. E., 1900, On the discovery and occurrence of minerals containing rare elements: Chem. News, v. 81, no. 2111, p. 217—218. . Northrop, S. A., 1944, Minerals of New Mexico, Albuquerque, New Mexico Univ. Press, p. 5—387. Nova, F. de P. B., 1945, Nota sobre as areias monaziticas de Guarapari, Espirito Santo: Mineracao e Metalurgia, v. 8, no. 46, p. 281—283. Nye, J. A., 1917, Monazite deposits in Ceylon: Foreign and Domestic Commerce, no. 23, p. 354. Nye, P. B., 1925, The sub-basaltic tin deposits of the Ringa- rooma valley: Tasmania Geol. Survey Bull. 35, p. 1—70. Nye, P. B., and Blake, F., 1938, The geology and mineral de- posits of Tasmania: Tasmania Geol. Survey Bull. 44, p. 1—113. Franklin Inst. Jour., v. 144, no. 860, U. S. Bur. BIBLIOGRAPHY Nye, P. B., Croll, I. C. H., and Dickinson, D. R., 1950, Mineral industry of Australia with particular reference to the past twenty years: Empire Mining and Metall. Cong, 4th, Great Britain, Proc., pt. 1, p. 39—54. Oakeshott, G. B., 1950, Black sands, in California Division of Mines Staff, Mineral commodities of California: Califor- nia Dept. Nat. Resources, Div. Mines Bull. 156, p. 133—— 136. Obalski, J., 1906, Rare earths in pegmatite veins: Mining Inst. Jour., v. 9, p. 72, 73. Obalski, M. T., 1904, Les mines d’amiante, de chromite et de mica au Canada: Mus. histoire naturelle [Paris] Bull., v. 10, no. 4, p. 163—174. O’Brien, P. L. A., 1958, An investigation into the source of the Irumi monazite: Northern Rhodesia Geol. Survey Rec- ords for the year ending 31st December, 1956, p. 26—28. Ogawa, Takudzi, 1903, Monazite as an enclosure in the topaz of Omi: Jour. Geography [Tokyo], v. 15, no. 175, p. 566— 568. [In Japanese] O’Harra, C. C., 1902, The mineral wealth of the Black Hills: South Dakota School Mines Bull. 6, p. 9—88. Oliveira, A. I. de, 1956, Brazil, in Jenks, W. F., Handbook of South American geology: Geol. Soc. America Mem. 65, p. 3—62. Oliveira. F. de P., 1902, The diamond deposits of Salobro, Brazil: Brazilian Mining Rev., v. 1, no. 1, p. 19—21. Olson, J. G., 1944, Economic geology of the Spruce Pine peg- matite district, North Carolina: North Carolina Div. Mineral Resources Bull., 43, pt. 1, p. 3—67. 1952, Pegmatites of the Cashiers and Zirconia districts, North Carolina: North Carolina Div. Mineral Resources Bull. 64, p. 1—32. Olson, J. C., and Adams, J. W., 1962, Thorium and the rare earths in the United States: U.S. Geol. Survey Mineral Inv. Resource Map MR—28, p. 1—16. Olson, J. C., Shawe, D. R., Pray, L. C., and Sharp, W. N., 1954, Rare-earth mineral deposits of the Mountain Pass district, San Bernardino County, California: U.S. Geol. Survey Prof. Paper 261, p. 1—75. Olson, J. C., and Wallace, S. R., Thorium and rare-earth min- erals in the Powderhorn district, Gunnison County, Col- orado: U.S. Geol. Survey Bull. 1027—0, p. 693—723. Ongley, Montague, 1947, Geological map of New Zealand: New Zealand Geol. Survey, 2 sheets. Ongley, Montague, and Macpherson, E. 0., 1923, The geology and mineral resources of the Collingwood Subdivision, Karamea Division: New Zealand Dept. Mines, Geol. Survey Branch Bull. 25, new ser., p. 1—52. Oriel, S. S., 1950, Geology and mineral resources of the Hot Springs window, Madison County, North Carolina: North Carolina Dept. Conserv. and Devel., Div. Mineral Re— sources Bull. 60, p. 1—70. Osterreichische Zeitschrift fiir Burg- und Hiittenwesen, 1909, Seltene Erden in den Sfidpolarregionen: Osterreichische Zeitschr. Burg- u. Hiittenwesen, v. 57, no. 33, p. 520. Osterwald, F. W., and Osterwald, D. B., 1952, Wyoming min- eral resources: Wyoming Geol. Survey Bull. 45, 215 p. Overstreet, W. C., 1960, Metamorphic grade and the abundance of Th0, in monazite, in Short papers in the geological sciences: U.S. Geol. Survey Prof. Paper 400—B, p. B55— B57. 1962, A review of regional heavy-mineral reconnaissance and its application in the southeastern Piedmont: South- eastern Geology v. 3, no. 3, p. 133—173. Canadian 317 Overstreet, W. C., and Bell, Henry, 3d, 1960, Notes on the Kings Mountain belt in Laurens County, South Carolina: South Carolina Devel. Board, Div. Geology, Geol. Notes, v. 4, no. 4, p. 27—30. 1962, Provisional geologic map of the crystalline rocks of South Carolina: U.S. Geol. Survey open-file report, 11 p. Overstreet, W. C., Bell, Henry, 3d, Rose, H. J., Jr., and Stern, T. W., 1961, Recent lead-alpha age determinations on zir- con from the Carolina Piedmont, in Short papers in the geologic and hydrologic sciences: U.S. Geol. Survey Prof. Paper 424—B, p. B103—B107. Overstreet, W. C., Cuppels, N. P., and White, A. M., 1956, Monazite in southeastern states: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 593—596. Overstreet, W. G., and Griffitts, W. R., 1955, Inner Piedmont belt, in Russell, R. J., ed., 1955, Guides to southeastern geology: Geol. Soc. America, p. 549—577. 1962, Preliminary geologic map of the southeast quarter of the Shelby quadrangle, Cleveland County, North Caro- lina: U.S. Geol. Survey Mineral Inv. Field Studies Map MF—250. Overstreet, W. C., Meuschke, J. L., and Moxham, R. M., 1962, Airborne radioactivity survey of the northern part of the Shelby quadrangle, Cleveland and Rutherford Counties, North Carolina: U.S. Geol. Survey Geophys. Inv. Map GP— 408. Overstreet, W. C., Overstreet, E. F., and Bell, Henry, 3d, 1960, Pseudomorphs of kyanite near Winnsboro, Fairfield Coun- ty, South Carolina: South Carolina Devel. Board, Div. Geology, Geol. Notes, v. 4, no. 5, p. 35—39. Overstreet, W. G., Theobald, P. K., J r., and Whitlow, J. W., 1959, Thorium and uranium resources in monazite placers of the western Piedmont, North and South Carolina: Mining Eng, v. 11, no. 7, p. 709—714. Overstreet, W. C., Theobald, P. K., Jr., Whitlow, J. W., and Stone, Jerome, 1956, Heavy-mineral prospecting: In- ternat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 692—694. Overstreet, W. C., Whitlow, J. W., White, A. M., and Griflitts, W. R., 1963, Geologic map of the southern part of the Casar quadrangle, Cleveland, Lincoln, and Burke Coun- ties, North Carolina, showing areas mined for monazite and mica: U.S. Geol. Survey Mineral Inv. Field Studies Map MF—257. Overstreet, W. C., Yates, R. G., and Grifiitts, W. R., 1963a, Heavy accessory minerals in the saprolite of the crys- talline rocks in the Shelby quadrangle, North Carolina: U.S. Geol. Survey Bull. 1162—F, 31 p. 1963b, Geology of the Shelby quadrangle, North Caro— lina: U.S. Geol. Survey Misc. Geol. Inv. Map I—384. Pabst, Adolf, 1938, Minerals of California: California Dept. Nat. Resources, Div. Mines Bull. 113, p. 3—344. 1951, Huttonite, a new monoclinic thorium silicate, including 0. O. Hutton, With an account of its occurrence, analysis, and properties: Am. Mineralogist, v. 36, p. 60— 69. Page, L. R., 1950, Uranium in pagmatites: 45, no. 1, p. 12—34. Page, L. R., and others, 1953, Pegmatite investigations 1942— 1945, Black Hills, South Dakota: U.S. Geol. Survey Prof. Paper 247, 228 p. Palache, Charles, Berman, Harry, and Frondel, Cliiford, 1951, Dana’s system of mineralogy, 7th ed., v. 2: New York, John Wiley and Sons, 1124 p. Econ. Geology, v. 318 Palache, Charles, Davidson, S. C., and Goranson, E. A., 1930, The hiddenite deposit in Alexander County. North Caro- lina: Am. Mineralogist, v. 15, no. 8, p. 280—306. Pallister, H. D., 1955, Index to the minerals and rocks of Alabama: Alabama Geol. Survey Bull. 65, p. 7—55. Pallister, J. W., 1958, Mineral resources of Somaliland Pro- tectorate: Overseas Geology and Mineral Resources, v. 7. no. 2, p. 154—165. Paone, James, 1958, Thorium: U.S. Bur. Mines Minerals Yearbook, 1957, v. 1, p. 1145—1155. 1959, Thorium: U.S. Bur. Mines Minerals Yearbook, 1958, v. 1, p. 1037—1044. 1960, Thorium: U.S. Bur. Mines Minerals Yearbook, 1959, v. 1, p. 1069—1076. Pardee, J. T., 1934, Beach placers of the Oregon coast: Geol. Survey Circ. 8, 41 p. Pardee, J. T., and Park, C. F., Jr., 1948, Gold deposits of the southern Piedmont: U.S. Geol. Survey Prof. Paper 213, 156 p. Parizek, E. J., 1953, A preliminary investigation of the geol- ogy of Clarke County, Georgia: Georgia Geol. Survey Bull. 60, pt. 2, p. 21—31. Parker, J. G., 1961, Rare-earth minerals and metals: Bur. Mines Minerals Yearbook, 1960, p. 927—934. 1962, Rare-earth minerals and metals: U.S. Bur. Mines Minerals Yearbook, 1962, v. 1, p. 1025—1034. Parker, J. M., 3d, and Broadhurst, S. D., 1959, Guidebook for Piedmont field trip featuring metamorphic facies in the Raleigh area, N.C.: Geol. Soc. America, Southeastern Section, Guidebook 1959 Ann. Mtg, Raleigh, N.C., p. 1—24. Parker, R. L., 1937, A note on the morphology of monazite: Am. Mineralogist, v. 22, no. 5, p. 572—580. Parrish, William, 1939, Unit cell and space group of monazite (La, Ce, Y)P04: Am. Mineralogist, v. 24, no. 10, p. 651— 652. ' Partridge, F. C., 1939, Note on the Durban beach sands: Soc. South Africa Trans, v. 41, p. 175. Paton, J. R., 1958, Geology—Federation of Malaya, in Agocs, W. B., and Paton, J. R., 1958, Extract from Columbo Plan report on airborne magnetometer and scintillation counter survey over parts of Perak, Salangor, and Negri Sembilan (area 1): Federation of Malaya Geol. Survey Dept. Econ. Bull. C—1.1, p. 2—A—2—W/ 1. Pegau, A. A., 1928, The Rutherford mines, Amelia County, Virginia: Am. Mineralogist, v. 13, no. 12, p. 583—588. 1929, The pegmatites of the Amelia, Goochland, and Ridgeway areas, Virginia: Am. Jour. Sci., ser. 5, v. 17, no. 102, p. 543—547. 1932, Pegmatite deposits Survey Bull. 33, p. 1—123. Peixoto, F. 0., and Guimaraes, D. J., 1953, Problemas de cronogeologia: Univ. Minas Gerais Escola de Eugen- haria, Inst. Pesquisas Radioativas Pub. 1, p. 3—35. Penfleld, S. L., 1882, On the occurrence and composition of some American varieties of monazite: Am. Jour. Sci., 3d sen, v. 24, no. 142, p. 250—254. Penfield, S. L., and Sperry, E. S., 1888, Mineralogical notes: Am. Jour. Sci., 3d ser., v. 36, no. 215, p. 317—331. Peng, C. J., 1947, Monazite in the tin sands of northeastern Kuangsi: Sci. Rec., v. 2, p. 111—115, Nanking, China. Penrose, R. A. F., 1903, The tin deposits of the Malay Penin- sula with special reference to those of the Kinta dis- trict: Jour. Geology, v. 11, no. 2, p. 135—154. U.S. U. S. Geol. of Virginia: Virginia Geol. THE GEOLOGIC OCCURRENCE OF MONAZITE Perry, E. S., 1957, Monazite deposits of South Carolina: South Carolina Devel. Board Div. Geology, Mineral Indus. Lab. Monthly Rept. [Bu11.], v. 1, no. 3, p. 3—5. Petar. A. V., 1935, The rare earths: U.S. Bur. Mines Inf. Circ. 6847, 46 p. Petterd, W. F., 1894, A catalogue of the minerals known to occur in Tasmania, with notes on their distribution: Royal Soc. Tasmania Papers and Proc. for 1893, p. 1—72. 1897, A classified list of the mineral species known to occur in Tasmania: Royal Soc. Tasmania Papers and Proc. for 1896, p. 23—28. 1902, The minerals of Tasmania: Royal Soc. Tasmania Papers and Proc. for 1900—1901, p. 75-84. 1903, Notes on unrecorded and other minerals occurring in Tasmania: Royal Soc. Tasmania Papers and Proc. for 1902, p. 18—33. 1910, The minerals of Tasmania: Papers and Proc. for 1910, p. 1—221. Pettijohn, F. J., 1949, Sedimentary rocks: and Brothers, p. 1—526. Petty, J. J., 1950, Bibliography of the geology of the State of South Carolina: South Carolina Univ. Pubs, ser. 2, Phys. Sci. Bull., no. 1, 86 p. Phair, George, and Antweiler, J. C., 1954, Mineralogy and geo- chemistry in Geologic investigations of radioactive de- posits—Semiannual progress report, December 1, 1953 to May 31, 1954: US. Geol. Survey TEI—440, p. 93—95, issued by Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. Phillips, W'. B., 1888, Mica mining in North Carolina (5): Eng. Mining Jour., v. 45, no. 22, p. 398. Pike, D. B., 1958, Thorium and rare earth bearing minerals in the Union of South Africa: United Nations Internat. Conf. Peaceful Uses Atomic Energy, 2d, Geneva 1958, Proc., v. 2, p. 91—96. Pliler, Richard, and Adams, J. A. S., 1959a, Distribution of thorium and uranium in the Mancos Shale (Cretaceous) [abs]: Geol. Soc. America Bull., v. 70, no. 12, pt. 2, p. 1656—1657. 1959b, Distribution of thorium and uranium in a Penn- sylvanian weathering profile [abs.]: Geol. Soc. America Bull., v. 70, no. 12, pt. 2, p. 1657. Poole, W. R., 1939, Zircon and rutile from beach black sand deposits: Chem. Eng. and Mining Review, v. 31, no. 365, p. 216—220; no. 366, p. 250—257. Pratt, J. H., 1901, The mining industry of North Carolina dur- ing 1900: North Carolina Geol. Survey Econ. Paper 4, 36 p. 1902, The mining industry in North Carolina during 1901: North Carolina Geol. Survey Econ. Paper 6, 102 p. 1903, Monazite: Mineral Collector, v. 9, no. 12, p. 179— 184. 1904a, The mining industry in North Carolina during 1902: North Carolina Geol. Survey Econ Paper 7, 27 p. 1904b, Monazite and zircon: U.S. Geol. Survey Mineral Resources U. S., 1903, p. 1163—1170. 1904c, The mining industry in North Carolina during 1903: North Carolina Geol. Survey Econ. Paper 8, 74 p. 1905, The mining industry in North Carolina during 1904: North Carolina Geol. Survey Econ. Paper 9, 95 p. 1906, Production of monazite, zircon, gadolinite, and columbite or tantalum minerals: U.S. Geol. Survey Mineral Resources U.S., 1905, p. 1313—1317. Royal Soc. Tasmania New York, Harper BIBLIOGRAPHY Pratt, J. H., 1907a, The mining industry in North Carolina during 1905: North Carolina Geol. Survey, Econ. Paper 11, 96 p. 1907b, The mining industry in North Carolina during 1906: North Carolina Geol. Survey, Econ. Paper 14, 144 p. 1908, The mining industry in North Carolina during 1907 with special report on the mineral waters: North Carolina Geol. Survey Econ. Paper 15, 176 p. 1913, New occurrence of monazite in North Carolina [abs]: Geol. Soc. America Bull., v. 24, no. 4, p. 686. 1914, The mining industry in North Carolina during 1911 and 1912: North Carolina Geol. Survey Econ. Paper 34, 342 p. 1916, Zircon, monazite, and other minerals used in the production of chemical compounds employed in the manu- facture of lighting apparatus: North Carolina Geol. Survey Bull. 25, 120 p. 1918, North Carolina minerals: Eng, v. 18, no. 9, p. 453—455. 1933, Gems and gem minerals of North Carolina: Mineralogist, v. 18, no. 4, p. 148—159. Pratt, J. H., and Berry, H. M., 1911, The mining industry in North Carolina during 1908, 1909, and 1910: North Caro- lina Geol. Survey, Econ. Paper 23, 134 p. 1919, The mining industry in North Carolina during 1913—17, inclusive: North Carolina Geol. and Econ. Sur- vey Econ. Paper 49, 170 p. Pratt, J. H., and Sterrett, D. B., 1908a, Monazite and monazite- mining in the Carolinas: Am. Inst. Mining Engineers Trans, v. 40, p. 313-340 [1910]. 1908b, Monazite and monazite mining in the Carolinas: Elisha Mitchell Sci. Soc. Jour., v. 24, no. 3, p. 61—86. 1909, Monazite industry in the Carolinas, U.S.A.: Min- ing Jour. [London], v. 86, no. 3854, p. 7. Prior, G. T., 1899, The “Aeschynite” from Hitterii, in Minerals from Swaziland—Niobates and titanates of the rare earths, chemically allied to Euxenite and Fergusonite; Cassiterite, Monazite, etc.: Mineralog. Mag. v. 12, no. 55, p. 96—101. Pulfrey, William, 1947, The geology and mineral resources of Kenya: Imp. Inst. [London] Bu11., v. 45, no. 3, p. 277— 299. . 1954, The geology and mineral resources of Kenya: Kenya Geol. Survey Bull. 1, p. 1—27. Quebec Miner, 1939, Prospectors of East Angus find results in gold sands: Quebec Miner, v. 5, no. 46, p. 5. Queensland Government Mining Journal, 1922, Monazite found in Nevada: Queensland Govt. Mining Jour., v. 23, no. 265, p. 247. Quinn, A. W., Jaffe, H. W., Smith, W. L., and Waring, C. L., 1957, Lead-alpha ages of Rhode Island granitic rocks compared to their geologic ages: Am. Jour. Sci., v. 255, no. 8, p. 547—560. Radominski, M. F., 1874, Sur un phosphate de cerium renfer- mant du fluor: Acad. Sci. [Paris] Comptes rendus, v. 78, p. 764—766. 1875, Reproduction artificielle de la monazite et de la xénotime: Acad. Sci. [Paris] Comptes rendus, v. 80, p. 304—307. Raeburn, Colin, 1926, The geology of Mama, Nassarawa Prov- ince: Nigeria Geol. Survey Bull. 9, p. 9—19. 1927a, Tinstone in the Calabar district: Survey Bull. 11, p. 72—88. 1927b, The geology of south-eastern Zaria: Geol. Survey Bull. 11, p. 9—38. Metall. and Chem. Am. Nigeria Geol. Nigeria 319 Raggatt, H. G., 1925, Chromium, cobalt, nickel, zirconium, titanium, thorium, cerium: New South Wales Geol. Survey Bull. 13, p. 3—17. Rama Rao, Bellu, 1942, Mineral deposits in Mysore: Geol. Mining, Metall. Soc. India Quart. Jour., v. 14, no. 4, p. 157—184. Ramaswamy, C., 1945, On the occurrence of beryl at Yediyoor, near Bangalore: Mysore Geol. Dept. Recs, v. 42, p. 81— 86. Rankama, Kalervo, and Sahama, Th. G., 1950, Geochemistry: Chicago, Chicago Univ. Press, 912 p. Rao, B. S. R., and Chetty, P. N., 1955, Distribution of radio- active beach sand: Jour. Sci. and Indus. Research, v. 14A, no. 10, p. 493—494. Rath, Gerhard vom, 1886, Ueber Monazit; Xenotim; Apatit; Spodumen; Turmalin; Rutil: Naturh. Ver. preussischen Rheinlande, Westfalens, u. des Regierungs-Bezirks Os- nabriick Verh., ser. 5, v. 43, p. 149—158. Ray, J. A., 1958, Minerals of the pegmatites of Crabtree, Mitchell County, North Carolina: Rocks and Minerals. v. 33, nos. 7—8, p. 291—300. Rayner, E. 0., 1955, Davidite and other radioactive occur- rences in the Thackaringa area, Broken Hill district: New South Wales Dept. Mines Tech. Reports, v. 3, p. 62—72. Reed, J. 0., 1937, Geology and ore deposits of the Warren mining district, Idaho County, Idaho: Idaho Bur. Mines and Geology Pamph. 45, p. 1—65. 1939, Geology and ore deposits of the Florence min- ing district, Idaho County, Idaho: Idaho Bur. Mines and Geology Pamph. 46, p. 1—44. Reed, J. G., and Gilluly, James, 1932, Heavy mineral assemb- lages of some of the plutonic rocks of eastern Oregon: Am. Mineralogist, v. 17, no. 6, p. 201—220. Reeve, W. H., and Deans, T., 1954, An occurrence of car- bonatite in the Isoka district of Northern Rhodesia: Colonial Geology and Mineral Resources, v. 4, no. 3, p. 271—281. Reid, A. M., 1919, The mining fields of Moina, Mt. Claude, and Lorinna: Tasmania Geol. Survey Bull. 29, p. 1—183. 1923, The Mount Bischofl tin field: Tasmania Geol. Survey Bull. 34, p. 1—171. Reid, R. R., 1960, Geology and heavy mineral content of placer deposits in the Elk City region, Idaho [abs]: Econ. Geology, v. 55, no. 6, p. 1325. Rice, W. N., 1885, Minerals from Middletown, Conn: Jour. Sci., ser. 3, v. 29, no. 171, p. 263. Rice, W. N., and Foye, W. G., 1927, Guide to the geology of Middletown, Connecticut and vicinity: Connecticut Geol. » Nat. History Survey Bull. 41, p. 5—137. Rice, W. N., and Gregory, H. E., 1906, Manual of the geology of Connecticut: Connecticut Geol. Nat. History Survey Bull. 6, p. 5—273. Richardson, J. A., 1939, The geology and mineral resources of the neighborhood of Raub, Pahang, Federated Malay States, with an account of the geology of the Raub Aus- tralian gold mine: Singapore, Federated Malay States Geol. Survey Dept. 166 p. Richartz, W., 1961, Uber kristallchemische Untersuchungen und magnetische Aufbereitung von Monazit: Fortschr. Mineralogie, v. 39, no. 1, p. 53—59. Am. 320 Rimann, Eberhard, 1913, Geologische und wirtschaftliche Betrachtungen fiber Deutsch-Siidwestafrika: Naturw. Ge- sell. Isis Dresden Sitzungsber. u. Abh., v. 1912, no. 5, p. 57—78. 1917, Sobre uma nova occurrencia de dumortierita: Ouro Preto Escola de Minas Annaes, no. 15, p. 19—25. Rittenhouse, Gordon, 1943, Transportation and deposition of heavy minerals: Geol. Soc. America Bull., v. 54, no. 12, p. 1725—1780. 1944, Sources of modern sands in the middle Rio Grande valley, New Mexico: Jour. Geology, v. 52, no. 3, p. 145—183. Roberts, A. E., 1955, How new $3,000,000 Highland plant re- covers titaniferous minerals: Mining World, v. 17, no. 11, p. 52—55, 72. Robertson, A. F., and Storch, R. H., 1955a, Camp Creek radio- active mineral placer area, Blaine and Camas Counties, Idaho: U.S. Atomic Energy Comm. RME—3136, p. 3—27. 1955b, Rock Creek radioactive mineral placer area, Blaine County, Idaho: US. Atomic Energy Comm. RME— 3139, p. 3—25. Robinson, G. D., Wedow, Helmuth, Jr., and Lyons, J. B., 1955, Radioactivity investigations in the Cache Creek area, Yentna district, Alaska, 1945: U.S. Geol. Survey Bull. 1024—A, p. 1—23. Rocha, E. F., 1939, Areias monaziticas e ilmeniticas do sul do Espirito Santo: Mineracao e Metalurgia, v. 4, no. 19, p. 18—20. Roche, H. de la, and Marchal, J., 1956, Géologie de 1’extréme sud-est, in Besairie, Henri, 1956, Rapport annuel du Service Géologique pour 1956: [Madagascar] Direction Mines et Géologie, Service Geol., p. 141—146. Roche, H. de la, Marchal, J., and Delbos, L., 1956, Prospection de monazite dans l’extreme sud-est de Madagascar, in Besairie, Henri, 1956, Rapport annuel du Service Géo- logique pour 1956: [Madagascar] Direction Mines et Géologie, Service Geol., p. 147—156. Rock Products, 1929, Monazite in sands along south Atlantic coast: Rock Products, v. 32, no. 19, p. 56. Rodgers, John, 1952, Absolute ages of radioactive minerals from the Appalachian region: Am. Jour. Sci., v. 250, p. 411—427. Roe, F. W., and others, 1957, British Territories in Borneo, Annual report of the Geological Survey Department for 1956, 212 p., Kuching, 1957. 1958, British Territories in Borneo, Annual report of the Geological Survey Department for 1957, 200 p., Ku- ching, 1959. 1959, British Territories in Borneo, Annual report of the Geological Survey Department for 1958, 247 p., Ku- ching, 1959. Roe, Hai Yong, and An, Chong Song, 1958, Ore dressing tests on the typical monazite sand from Hakiri, Tandong— myon, Taeduk-gun, Chungchong Nam-do: Korea Geol. Survey Tech. Paper 1, p. 36-37. Roe, Hai Yong, Cho, Myong Sung, and An, Chong Song, 1958, A report on ore-dressing tests of Kosong ilmenite sand: Korea Geol. Survey Tech. Paper 1, p. 38—41. Rogers, A. W., 1916, Notes on the occurrence of radioactive minerals in South Africa: Geol. Soc. South Africa Trans, v. 18, p. 5—10. THE GEOLOGIC OCCURRENCE OF MONAZITE Roig, M. S., 1928, Havana Instituto national de investiga- ciones cientificas y Museo de historia natural: Havana, Cuba, 220 p. Rolff, P. A. M. de A., 1946, Minerais dos pegmatitos da Bor- borema: Brasil Divisao Fomento Produgao Mineral B01. 78, p. 11—76. 1947, A monazita de S50 Joao del Rei, Minas Gerais: [Univ. Brasil] Escola de Minas Rev., v. 12, no. 6, p. 29—30. ———1948, Possibilidades econémicas da monazite. de Sao Joao del Rei: Ouro Préto Escola de Minas Rev., v. 13, no. 4, p. 15—18. 1955, Monazita no vale do Serido: Escola de Minas Rev., v. 20, no. 1, p. 43. Roots, E. F., 1946, Cerium and thorium—distribution, occur- rence, production and uses: Western Miner, v. 19, no. 8, p. 50—56. Rose, H. J ., J r., Blade, L. V., and Ross, Malcolm, 1958, Earthy monazite at Magnet Cove, Arkansas: Am. Mineralogist, v. 43, nos. 9—10, p. 995-997. Rose, H. J., Jr., Murata, K. J., and Carron, M. K., 1954, A chemical spectrochemical method for the determination of rare earth elements and thorium in cerium minerals: Spectrochim. Acta, v. 6, p. 161—168. Ross, C. P., 1941, The metal and coal mining districts of Idaho, with notes on the nonmetallic mineral resources of the state: Idaho Bur. Mines and Geology Pamph. 57, p. 1—110. Ross, Kenneth, 1906, Some experiments on the west coast: New Zealand Mines Rec., v. 10, no. 1, p. 12—13. Rothrock, E. P., 1944, Mineral resources, Part 3 of A geology of South Dakota: South Dakota Geol. Survey Bull. 15, p. 7—225. Rousseaux, J., 1939, The Belgian Congo: Jour., v. 11, no. 150, p. 1477—1480. Rove, O. N., 1952, Mining geology: v. 4, no. 2, p. 140—143. Rowe, J. P., 1928, Minor metals and non-metallic minerals of Montana: Eng. Mining Jour., v. 125, no. 20, p. 816—818. Rowley, R. C., 1956, Monazite deposit—section 60, hundred of Myponga: South Australia Mining Rev., no. 101, p. 63— 64. Russ, W., 1927, The geology of the Banke and Liruein Kano Hills: Nigeria Geol. Survey Bull. 11, p. 49—71. Russell, H. D., Hiemstra, S. A., and Groeneveld, D., 1954, The mineralogy and petrology of the carbonatite at Loolekop, eastern Transvaal: Geol. Soc. South Africa Trans, v. 57, p. 197—208. Russell, R. D., 1937, Mineral composition of Mississippi River sands: Geol. Soc. America Bull, v. 48, no. 9, p. 1307—1348. Sahinen, U. M., 1957, Mines and mineral deposits Missoula and Ravalli Counties, Montana: Montana Bur. Mines and Geology Bull. 8, p. 1—63. Saint-Ours, J. de, 1955, Prospection de la province petrographi- que d’Ampasindava, in Besairie, Henri, 1955, Rapport an- nuel du Service Géologique pour 1955: [Madagascar] Direction Mines et Géologie, Service Geol., p. 21—23. [Univ. Brasil] Rhodesian Mining Mining Eng. [New York], 1956, Prospection de 1’extreme nord du socle cristallin et de son contact sedimentaire, in Besairie, Henri, 1956, Rapport annuel du Service Géologique pour 1956: [Mad- agascar] Direction Mines et Géologie, Service Geol., p. 21— 28. BIBLIOGRAPHY Saint-Smith, E. 0., 1915, Its geology and mineral resources, Part 4 of Annan River tinfield, Cooktown district, North Queensland: Queensland Govt. Mining Jour., v. 16, no. 186, p. 553—563. 1916, Geology and mineral resources of the Cooktown district tinfields: Queensland Geol. Survey Pub. 250, p. 1—211. Sakurai, I., 1941, Xenotime from Ishikawa, Fukushima Pre- fecture: Geol. Soc. Japan Jour., v. 48, p. 98. Sampson, D. N., 1957, A brief comparison between the mica- bearing pegmatites of the Uluguru Mountains and the Mikese area, Morogoro District, Tanganyika: Comm. Tech. Co-op. in Africa South of the Sahara, Comités régionaux Centre, Est et Sud, Conf. de Tananarive Avril 1957, Géologie, v. 1, p. 139—156. Salt Lake Mining Review, 1910, Mining for monazite: Lake Mining Rev., v. 12, no. 14, p. 35. Sanders, 0. W., Jr., 1929, A composite stock at Snowbank Lake in northeastern Minnesota: J our. Geology, v. 37, no. 2, p. 135—149. Sanderson, J. 0., 1915, The radio-active content of certain Minnesota soils: Am. Jour. Sci., ser. 4, v. 39, no. 232, p. 391—397. Sanderson, L., 1943, The mineral monazite: 28, no. 164, p. 71-72. Sanford, Samuel, and Stone, R. W., 1914, Useful minerals of the United States: U.S. Geol. Survey Bull. 585, 250 p. Santmyers, R. M., 1930, Monazite, thorium, and cerium: U.S. Bur. Mines Inf. Circ. 6321, p. 1—43. Sarkar, T. 0., 1941, The lead ratio of a crystal of monazite from the Gaya district, Bihar: Indian Acad. Sci. Proc., sec. A, v. 13, no. 3, p. 245-248. Sasaki, Jiro, 1926, The determination of the helium content of some Japanese minerals: Chem. Soc. Japan Bull., v. 1, no. 12, p. 253-254. Sastry, 0. S., 1954, Heavy minerals of charnockites and lep- tynites: Current Sci. [Bangalore], v. 23, no. 5, p. 151— 152. Sato, Denzo, 1926, Some minerals containing rarer elements [abs]: Pan-Pacific Sci., Cong, 3rd, Tokyo, Proc., v. 1, p. 865—866 [1928]. Savage, C. N., 1960, Nature and origin of central Idaho blacksands: Econ. Geology, v. 55, no. 4, p. 789-796. Schairer, J. F., 1931, The minerals of Connecticut: Connecti- cut Geol. Nat. History Survey Bull. 51, p. 11—121. Schaller, W. T., 1919, Mica, monazite, and lithium minerals, in McCaskey, H. D., and Burchard, E. F., 1919, Our min- eral supplies: U.S. Geol. Survey Bull. 666, p. 153—158. 1922, Thorium, zirconium, and rare-earth minerals: U.S. Geol. Survey Mineral Resources U.S., 1919, pt. 2, p. 1—32. 1933, A large monazite crystal from North Carolina: Am. Mineralogist, v. 18, no. 10, p. 435—439. Scheibe, R., 1931, La mineria en Colombia: Minas y Petréleo [Bogata] 301., v. 5, nos. 28—30, p. 74—90. Schmidt, R. G., 1961, Natural gamma aeroradioactivity of the Savannah River Plant area, South Carolina and Georgia: U.S. Geol. Survey Geophys. Inv. Map GP—306. 1962, Aeroradioactivity survey and areal geology of the Savannah River Plant area, South Carolina and Georgia (ARMS—1): U.S. Atomic Energy Comm. CEX—58.4.2, 41 p. Salt Metallurgia, v. 321 Schmidt, R. G., and Asad, S. A., 1962, Beach placers contain- ing radioactive minerals, Bay of Bengal, East Pakistan, in Short papers in geology and hydrology: U.S. Geol. Survey Prof. Paper 450—0, p. 012—014. 1963, A reconnaissance survey of radioactive beach sand at Cox’s Bazar: Geol. Survey Pakistan Interim Geol. Rept. IGR—S, 14 p. Schoep, Alfred, 1930, Les minéraux du gite uran‘ifere dn Katanga: Musée royal Congo Belge Annales, Minéralogie, géologie et paléontogie, sér., 1, v. 1, pt. 2, p. 1—42. Schoep, Alfred, Hacquaert, A. L., and Goossens, Albert, 1932, Recherches lithologiques sur des roches carbonatées du Katanga: Musée royal Congo Belge Annales, Minéralogie, geologic et Paléontogie, sér. 1, v. 2, pt. 1, p. 5—103. Schrader, F. 0., 1910, An occurrence of monazite in northern Idaho: U.S. Geol. Survey Bull. 430, pt. 1, p. 184—191. Schrader, F. 0., Stone, R. W., and Sanford, Samuel, 1917, Useful minerals of the United States: U.S. Geol. Survey Bull. 624, 412 p. Schreiter, R., 1922, fiber Monazit und seine Vorkommen: Freiberger Geol. Gesell., v. 9, p. 39—44, [1923]. Schwartz, Jack, 1944, Southern California localities: and Minerals, v. 19, no. 1, p. 2. Rocks ' Schwarz, E. H. L., 1917, Diamonds from the Molteno beds: Geol. Soc. South Africa Trans, v. 19, p. 33—35. Scientific American, 1899, Monazite production in North Caro— lina: Sci. American, v. 80, no. 7, p. 101. Scrivenor, J. B., 1906, Federated Malay States Geologist’s re- port for the year 1905: Selangor Govt. Gaz. Supp, p. 1—2. 1907a, Geologist’s report of progress—September, 1903— January, 1907: Kuala Lampur, Federated Malay States Govt. Press, p. 1—44. 1907b, Gold and tin mines of the Federated Malay States, with special reference to Pahang: Mining Jour. [London], v. 81, no. 3746, p. 781—782; no. 3747, p. 793; no. 3748, p. 843—844; and no. 3749, p. 866-867. 1910, Federated Malay States Geologist’s annual report for the year 1909: Selangor Govt. Gaz. Supp, p. 1—4. 1911, Federated Malay States Geologist’s annual report for the year 1910: Federated Malay States Govt. Gaz. Supp, p. 1—3. 1912, Federated Malay States Geologist’s annual report for the year 1911: Federated Malay States Govt. Gaz. Supp, p. 1—4. 1915, Federated Malay States Geologist’s annual report for the year 1914: Federated Malay States Govt. Gaz. Supp, p. 1—5. 1920, Federated Malay States Geologist’s annual report for the year 1919: Federated Malay States Govt. Gaz. Supp, p. 1—8. 1928, The geology of Malayan ore-deposits: Macmillan and 00., 216 p. 1931a, Federated Malay States report of the Geological Survey Department for the year 1930: Federated Malay States Govt. Gaz. Supp. p. 1—20. 1931b, The geology of Malaya: and 00., p. 1—217. Seaborg, G. T., 1958, The transuranium elements: New Haven, Conn, Yale Univ. Press, 328 p. Sears, 0. E., Jr., 1955, Monazite deposits in Virginia [abs]: Virginia Jour. Sci., new sen, v. 6, no. 4, p. 281. London, London, Macmillan 322 Sellards, E. H., and Evans, G. L., 1943, Index to Texas mineral resources, in Sellards, E. H., ed., 1943, Texas mineral resources: Texas Univ. Pub. 4301, p. 359—383 [1946]. Sen, A. M., 1935, General report of the Geological Department for the year 1933—34: Mysore Geol. Dept. Recs, v. 33, p. 1—35. Shainin, V. E., 1948, Economic geology of some pegmatites in Topsham, Maine: Maine Geol. Survey Bull. 5, p. 5—32. Shannon, E. V., 1926, The minerals of Idaho: U.S. Natl. Mus. Bull. 131, p. 1—483. Sharma, N. L., and Purkayastha, S., 1934, The heavy mineral assemblage of white clay and ochres associated with the laterite of Sohawal State (G. 1.): Geol., Mining, Metall. Soc. India Quart. Jour., v. 6, no. 2, p. 49—54. Sharp, W. N., and Cavender, W. S., 1953, Thorium deposits of the Lemhi Pass district, Lemhi County, Idaho, and Beaverhead County, Montana [abs]: Geol. Soc. America Bull., v. 64, no. 12, pt. 2, p. 1555. Shaw, D. M., 1958, Radioactive mineral occurrences of the Province of Quebec: Quebec Dept. Mines, Mineral De- posits Branch Geol. Rept. 80, p. 1—52. Shelton, J. E., and Stickney, W. A., 1955, Beneficiation studies of columbian-tantalum-bearing minerals in alluvial black- sand deposits: U.S. Bur. Mines Rept. Inv. 5105, p. 1—16. Shen, J. T., 1956, Exploration of monazite and associated min- erals in the Province of Taiwan, China: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 147—151. Shepard, C. U., 1837a, Description of edwardsite, a new min- eral: Am. Jour. Sci., ser. 1, v. 32, no. 1, p. 162—166. 1837b, Notice of eremite, a new mineral species: Jour. Sci., ser. 1, v. 32, no. 2, p. 341—342. 1840, On the identity of edwardsite with monazite, (mengite,) and on the composition of the Missouri me- teorite: Am. Jour. Sci., ser. 1, v. 39, no. 2, p. 249—255. 1849, Notices of American minerals: Am. Jour. Sci., ser. 2, v. 8, no. 23, p. 274-275. 1852, A treatise on mineralogy [3d ed.]: B. L. Hamlen, 451 p. Shepherd, S. R. L., 1938, Mica Creek tin deposit near Mount Isa: Queensland Govt. Mining Jour., v. 39, no. 454, p. 95—96. Shibata, Yuji, 1926, The chemical investigation of Japanese minerals containing rarer elements: Pan-Pacific Sci. Cong, 3d, Tokyo, Proc., v. 1, p. 852—865 [1928]. Shibata, Yuji, and Kimura, Kenjiro, 1921a, Analysis of co- lumbite and monazite found in Iwaki, Ishikawa-machi, Fukushima Prefecture, Part 2 of Chemical studies of rare-earth element minerals found in the Orient: Japan Chem. Soc. Jour., v. 42, no. 11, p. 957—964. [In Japanese] 1921b, Analysis of naegite, fergusonite, and monazite found at Naegi in Gifu Prefecture, Part 1 of Chemical studies of rare-earth element minerals found in the Orient: Japan Chem. Soc. Jour., v. 42, no. 1, p. 1—16. [In Japanese]. 1923a, Analyses of fergusonite, naegite and monazite, of Naegi, Mino Province, Part 1 of The chemical investiga- tion of Japanese minerals containing rarer elements: Japanese Jour. Chem. Trans. and Abs., v. 2, no. 1, p. 1—6. 1923b, Analyses of columbite, monazite, samarskite and ishikawaite (a new mineral), of Ishikawa, Iwaki Prov- ince, Part 3 of The chemical investigation of Japanese minerals containing rarer elements: Japanese Jour. Chem. Trans. and Abs, v. 2, no. 1, p. 13—20. Am. New Haven, THE GEOLOGIC OCCURRENCE OF IMONAZITE Shockey, P. N., 1957, Reconnaissance geology of the Lees- burg quadrangle, Lemhi County, Idaho: Idaho Bur. Mines and Geology Pamph. 113, p. 1—42. Shufflebarger, T. E., Jr., 1958, Titanium minerals in the valley of the Wateree River, Kershaw, Richland, and Sumter Counties, [South Carolina: South Carolina Devel. Board Div. Geology, Mineral Indus. Lab. Monthly Bull., v. 2, no. 4, p. 23—32. Shukri, N. M., 1949, The mineralogy of some Nile sediments: Geol. Soc. London Quart. Jour., v. 105, pt. 4, no. 420, p. 511—529 [1950]. Silliman, Benjamin, Jr., 1844, Sillimanite and monazite: Am. Jour. Sci., v. 46, no. 1, p. 207-208. Silver, L. T., and Grunenfelder, Marc, 1957, Alteration of ac- cessory allanite in granites of the Elberton area, Georgia [abs]: Geol. Soc. America Bull., v. 68, no. 12, pt. 2, p. 1796. Simons, A. L., 1939, Geological investigations in NE. Nether- lands Timor: Amsterdam Univ. Geol. Inst. Mededeel. 85, p. 1—103. Simpson, E. S., 1912a, The occurrence of monazite at Coogle- gong and Moolyella, in Miscellaneous Reports 9-32: Western Australia Geol. Survey Bull. 48, p. 44—48. 1912b, The rare metals and their distribution in Western Australia: Nat. Hist. and Sci. Soc. Western Australia J our., v. 4, p. 83—108. 1914, The rare metals and their distribution in Western Australia; Western Australia Geol. Survey Bull. 59, Misc. Rept. 35, p. 31—56. 1919, Rare metals in Western Australia, in The Mining Handbook: Western Australia Geol. Survey Mem. 1, chap. 2, pt. 3, sec. 18, p. 3—10. 1952, Minerals of Western Australia, v. 3: William H. Wyatt, Govt. Printer, 714 p. Siple, G. E., Neiheisel, James, and Perry, E. S., 1959, Aspects of heavy-mineral distribution of the South Carolina Coastal Plain [abs]: Geol. Soc. America Bull., v. 70, no. 12, pt. 2, p. 1769—1770. Sloan, Earl, 1904, The mineral resources of South Carolina: Am. Mining Cong, 7th Ann. Sess., Denver, Proc., pt. 2, p. 129—160 [1905]. 1908, Catalogue of the mineral localities of South Carolina: South Carolina Geol. Survey Bull. 2, 4th ser., p. 7—505 [reprinted 1958]. Smeeth, W. F., and Iyengar, P. S., 1916, Mineral resources of Mysore: Mysore Dept. Mines and Geology Bull. 7, p. 1—193. Smith, E. A., and McCalley, Henry, 1904, Index to the mineral resources of Alabama: Alabama Geol. Survey Bull. 9, p. 5—79. Smith, H. C., 1896, Monazite in Brazil: U.S. State Dept. Con- sular Repts., v. 50, no. 186, p. 372—373. Smith, W. C., 1956, A review of some problems of African carbonatites: Geol. Soc. London Quart. Jour., v. 112, pt. 2, no. 446, p. 189—219. ‘ Smith, W. L., and Cisney, E. A., 1956, Bastnaesite, an acces- sory mineral in the Redstone granite from Westerly, Rhode Island: Am. Mineralogist, v. 41, nos. 1—2, p. 76—81. Smith, W. L., Franck, M. L., and Sherwood, A. M., 1957, Ura- nium and thorium in the accessory allanite of igneous rocks: Am. Mineralogist, v. 42, nos. 5—6, p. 367—378. Society Chemical Industry Journal, 1917, Ceylon monazite sands and other thoria minerals: Soc. Chem. Industry Jour., v. 36, no. 23, p. 1203. Perth, BIBLIOGRAPHY Society Chemical Industry Journal, 1922, Monazite in the Malay Peninsula: Soc. Chem. Industry Jour. Rev., v. 41, no. 21, p. 484. Sohon, J. A., 1951, Connecticut minerals, their properties and occurrence: Connecticut Geol. Nat. History Survey Bull. 77, p. 1—133. Son, Chi Moo, and Won, Chong Kwan, 1959, On the source rocks of the monazite placer deposits in Jungup and Damyang areas, Chollado: Korean Geol. Survey Bull. 3, p. 116—132. [In Korean, English summary] Soulé de Lafont, D., 1958, Pegmatites lithiques et pneumato- lytes stanniferes au Soudan et au Sénégal: Chronique mines d’outre-mer et recherche miniere, v. 26, no. 267, p. 245—251, Paris. Sousa Torres, Arthur de, 1952, Note sur l’analyse d’une mona- zite du filon de Boa Esperanca, Alto Ligonha, Mogam- bique: Soc. Geol. Portugal Bol., v. 10, p. 189—192. South Africa Geological Survey, 1940, The mineral resources of the Union of South Africa: Pretoria, South Africa Geol. Survey, 544 p. South African Mining and Engineering Journal, 1947, The min- erals of Mozambique: South African Mining and Eng. Jour., v. 58, pt. 1, no. 2846, p. 769—771. 1956a, Uranium ores in Nyasaland: South African Mining and Eng. Jour., v. 67, pt. 2, no. 3324, p. 645. 1956b, Recent discoveries in Tanganyika: South African Mining and Eng. Jour., v. 66, pt. 2, no. 3283, p. 827. South African Mining Journal, 1911, Mining in German Af- rica: report for the year 1909—1910: South African Min- ing Jour., v. 9, pt. 1, no. 429, p. 550. 1912, Rarer minerals in South Africa: South African Mining Jour., v. 22, pt. 1, no. 1105, p. 401. Spence, H. S., 1930, Pegmatite minerals of Ontario and Que- bec: Am. Mineralogist, v. 15, no. 9, p. 430—450, no. 10, p. 474—496. Spence, H. S., and Muench, O. B., 1935, Monazite from West Portland Township, Quebec: Am. Mineralogist, v. 20, no. 10, p. 724—732. Sproat, I. E., 1916, Refining and utilization of Georgia kao- lins: U.S. Bur. Mines Bull. 128, 59 p. Staatz, M. H., 1947, Iron sand resources of Japan: Tokyo General Headquarters, Supreme Commander Allied Pow- ers, Nat. Resources Sec. Rept. 98, p. 2—30. Staatz, M. H., and 'I'rites, A. F., 1955, Geology of the Quartz Creek pegmatite district, Gunnison County, Colorado: U.S. Geol. Survey Prof. Paper 265, 111 p. Staley, W. W., 1940, An abridged bibliography of the mineral industry of the state of Idaho: Idaho Bur. Mines and Geology. Press Bull. 19, p. 1—8. 1952, Monazite in Idaho: The Compass, v. 29, no. 4, p. 303—312. Staley, W. W., and Browning, J. S., 1949, Preliminary inves- tigation of concentrating certain minerals in Idaho placer sand: Idaho Bur. Mines and Geology Pamph. 87, p. 1—23. Stanfier, H., 1945, The geology of the Netherlands Indies, in Honig, Pieter, and Verdoorn, Frans, 1945, Science and scientists in the Netherlands Indies: New York, Board for the Netherlands Indies, Surinam and Curacao, p. 320—335. Steacy, H. R., 1953, An occurrence of uraninite in a black sand: Am. Minerologist, v. 38, nos. 5—6, p. 549—550. Stebinger, Eugene, 1914, Titaniferous magnetite beds on the Blackfeet Indian reservation, Montana: U.S. Geol. Survey Bull. 540—H, p. 329—337. 323 Steidtmann, Edward, and Cathcart, S. H., 1922, Geology of the York tin deposits, Alaska: U.S. Geol. Survey Bull. 733, 130 p. Stern, T. W., 1950, A catalog of study material of radioac- tive minerals: U.S. Geol. Survey TEI—129, open-file report, 80 p. Sterrett, D. B., 1907a, Monazite, in Pratt, J. H., 1907, The mining industry in North Carolina during 1906: North Carolina Geol. Survey, Econ. Paper 14, p. 108—124. 1907b, Monazite and zircon: U.S. Geol. Survey Mineral Resources U.S., 1906, p. 1195—1209. 1908a, Monazite and zircon: U.S. Geol. Survey Mineral Resources U.S., 1907, pt. 2, p. 785—794. 1908b, Monazite deposits of the Carolinas: U.S. Geol. Survey Bull. 340—D, p. 272—285. 1908c, Monazite deposits of the Carolinas, in Pratt, J. H., and Berry,- H. M., 1911, The mining industry in North Carolina during 1908, 1909 and 1910: North Car- olina Geol. Survey Econ. Paper 23, p. 72—81. 1911, Monazite and zircon: U.S. Geol. Survey Mineral Resources U.S., 1909, pt. 2, p. 897—905. 1913, Gems and precious stones: U.S. Geol. Mineral Resources U.S., 1912, pt. 2, p. 1023—1060. Stockley, G. M., 1939, Outline of the geology of the Uruwira mineral field: Tanganyika Territory Dept. Lands and Mines, Geol. Div. Short Paper 22, p. 5—22. 1947, The geology and mineral resources of Tanganyika Territory: Imp. Inst. [London] Bull., v. 45, no. 4, p. 375- 406. Stockwell, C. H., ed., 1957, Geology and economic minerals of Canada [4th ed.): Canada Geol. Survey Econ. Geology Sen, no. 1, p. 1—517. Storch, R. H., 1958a, Ilmenite and other black-sand minerals in the Gold Fork placer deposit, Valley County, Idaho: U.S. Bur. Mines Rept. Inv. 5395, p. 1—15. 1958b, Ilmenite and other black-sand minerals in the Deadwood placer deposit, Valley County, Idaho: U.S. Bur. Mines Rept. Inv. 5396, p. 1—15. Storch, R. H., and Robertson. A. F., 1954, Beaver Valley monazite placer area, Valley County, Idaho: U.S. Atomic Energy Comm. RME—3132, p. 3—15. Stose, G. W., and Smith, R. W., 1939, Geologic map of Georgia: Georgia Div. Mines, Mining, and Geology, map. Stow, M. H., 1955a, Report of radiometric reconnaissance in Virginia, North Carolina, eastern Tennessee, and parts of South Carolina, Georgia, and Alabama: U.S. Atomic Energy Comm. RME—3107, p. 3—33. 1955b, Uranium in Virginia: Virginia Minerals, v. 1, no. 4, p. 1—5. Strod, A. J., 1953, Thorium and its sources in the western hemisphere: Am. Ceramic Soc. Bull., v. 32, no. 4, p. 122— 123. Strutt, R. J., 1904, A study of the radio-activity of certain minerals and mineral waters: Royal Soc. London Proc., v. 73, no. 491, p. 191—197. Stuckey, J. L., and Conrad, S. G., 1958, Explanatory text for geologic map of North Carolina: North Carolina Div. Mineral Resources Bull. 71, p. 2—51. Sutton, F. A., 1946, Geology of Maracaibo Basin, Venezuela: Am. Assoc. Petroleum Geologists Bull., v. 30, no. 10, p. 1621-1741. Symons, H. H., 1936, Minerals and statistics: California Jour. Mines and Geology, v. 32, no. 1, p. 115—117. Survey 324 Tanner, W. F., Mullins, Allan, and Bates, J. D., 1961, Possible masked heavy mineral deposit, Florida panhandle: Econ. Geology, v. 56, no. 6, p. 1079—1087. Tattam, C. M., 1936, Interim report on the geology of the Borgu Division: Nigeria Geol. Survey Ann. Rept. 1935, p. 6—12. 1938, Water supply of Dikwa Division: Nigeria Geol. Survey Ann. Rept. 1937, p. 8—10. Teague, K. H., and Furcron, A. S., 1948, Geology and mineral resources of Rabun and Habersham Counties, Georgia: Georgia Dept. Mines, Mining, and Geology, map. Teale, E. 0., 1936, Provisional geological map of Tanganyika with explanatory notes [rev. ed.]: Tanganyika Territory Dept. Lands and Mines, Geol. Div. Bull. 6, p. 1—50. Teas, L. P., 1921, Preliminary report on the sand and gravel deposits of Georgia: Georgia Geol. Survey Bull. 37, p. 1—392. Thailand Delegation, 1956, Natural occurrence of uranium and thorium in Thailand: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 201—203. Thomas, R. G., 1924, A monazite-bearing pegmatite near Nor- manville: Royal Soc. South Australia Trans. and Proc., v. 48, p. 258—268. Thompson, J. V., 1958, The Humphreys spiral concentrator, its place in ore dressing: Mining Eng. [New York], v. 10, no. 1, p. 84—87. Thompson, L. S., 1928, The upland diamond deposits of the Diamantina district, Minas Geraes, Brazil: Econ. Geology, v. 23, no. 7, p. 705—723. Thomson, A. G., 1952a, Mineral resources in Nyasaland: Min- ing Jour. [London], v. 238, no. 6090, p. 272. 1952b, British Honduras: Mining Jour. [London], v. 238, no. 6084, p. 318, 319. Thomson, F. A., and Ballard, S. M., 1924, Geology and gold resources of north central Idaho: Idaho Bur. Mines and Geology Bull. 7, p. 5—127. Thoreau, J., Breckpot, R., and Vaes, J. F., 1936, La monazite de Shinkolobwe (Katanga): Acad. royale Belgique Bull. c1. sci., 5th ser., v. 22, no. 10, p. 1111—1122. Thoreau, J., and de Terdonck, R. du T., 1933, Le gite d’ura- nium de Shinkolobwe-Kasolo (Katanga): Inst. royal co- lonial belge, Sec. sci. nat. et méd., Mem., colln. en quarto, v. 1, pt. 8, p. 3—46. Thorpe, Albert, 1895, Monazite—a mineral containing helium: Chem. News [London], v. 72, no. 1860, p. 32. Tickell, F. G., 1924, The correlative value of the heavy minerals: Am. Soc. Petroleum Geologists Bull., v. 8, no. 2, p. 158—168. Tilton, G. R., and Nicolaysen, L. 0., 1957, The use of mona- zites for age determination: Geochim. et Cosmochim. Acta, v. 11, nos. 1—2, p. 28—40. Tipper, G. H., 1914, The monazite sands of Travancore: India Geol. Survey Recs, v. 44, pt. 3, p. 186—195. 1919, On pitchblende, monazite and other minerals from Pichhli, Gaya District, Bihar and Orissa: India Geol. Survey Recs, v. 50, pt. 4, p. 255—262. Tong, S. Y., 1956, Occurrence of uranium and thorium in South Korea: Internat. Cont. Peaceful Uses Atomic En- ergy, Geneva 1955, Proc., v. 6, p. 176—177. Trace, R. D., 1960, Significance of unusual mineral occur- rence at Hicks Dome, Hardin County, Illinois, in Short papers in the geological sciences: U.S. Geol. Survey Prof. Paper 400—B, p. B63-B64. THE GEOLOGIC OCCURRENCE OF MONAZITE Traill, R. J., 1954, A preliminary account of the mineralogy of radioactive conglomerates in the Blind River region, Ontario: Canadian Mining Jour., v. 75, no. 4, p. 63-68. Trainer, D. W., 1930, Mineral concentrates of beach sand: Am. Mineralogist, v. 15, no. 5, p. 194—197. 1932, The Tully limestone of central New York: New York Mus. Bull., no. 291, p. 3—43. Treasher, R. C., 1940, Field identification of minerals for Ore- gon prospectors and collectors: Oregon Dept. Geology and Mineral Indus. Bull. 16, 128 p. Trites, A. F., Jr., and Tooker, E. W., 1952, Uranium and thorium deposits in east-central Idaho and southwestern Montana: US. Geol. Survey TEI—140 (Pt. 1), 98 p., issued by US. Atomic Energy Comm. Tech. Inf. Service. Oak Ridge, Tenn. 1953, Uranium and thorium deposits in east-central Idaho and southwestern Montana: US. Geol. Survey Bull. 988—H, p. 157-209. Trumbull, James, Lyman, John, Pepper, J. F., and Thomasson, E. M., 1958, An introduction to the geology and mineral resources of the continental shelves of the Americas: US Geol. Survey Bull. 1067, 92 p. Truchot, P., 1898, On the occurrence and extraction of thorite, monazite, and zircon: Chem. News [London], v. 77, no. 2000, p. 134—135, no. 2001, p. 145—147. Tsuda, Hideo, 1941, Minerals from Korea: Chosen Mineral Survey Rept. 15, p. 1—357 plus 47, pl. 24, Tokyo, Sanseido Co. [In Japanese] Turner, F. J., 1943, Zircon in sedimentary rocks of Otago: New Zealand Jour. Sci. and Technology, v. 25, no. 2, p. 89—90. 1948, Mineralogical and structural evolution of the metamorphic rocks: Geol. Soc. America Mem. 30, 342 p. Turner, H. W., 1902, Notes on unusual minerals from the Pacific States: Am. Jour. Sci., ser. 4, v. 13, no. 77, p. 343-346. 1928, Review of the radioactive minerals of Madagas- car: Econ. Geology, v. 23, no. 1, p. 62—84. Twelvetrees, W. H., and Petterd, W. F., 1898, On the topaz quartz porphyry or stanniferous elvan dykes of Mount Bischoff: Royal Soc. Tasmania Papers and Free. for 1897, p. 119—128. Twinem, J. 0., 1932a, Bibliography on the geology of Maine from 1836 to 1930: [Maine Geol. Survey], State Geologist’s Rept., 1930—32, p. 10—98. 1932b, Bibliography on the geology of Maine from 1836 to 1930, m Rand, J. R., 1958, Bibliography on Maine geol- ogy, 1836—1957 2 Maine Geol. Survey, p. 5—92. Tyler, S. A., 1934, A study of sediments from the North Carolina and Florida coasts: Jour. Sed. Petrology, v. 4, no. 1, p. 3—11. Ueda, Tateo, 1953, The crystal structure of monazite (CeP04) : Kyoto Univ. Coll. Sci. Mem., ser. B, v. 20, no. 4, p. 227—- 246. Uganda Protectorate Geological Survey, 1949, Annual report of the Geological Survey Department for the year ended 31st December, 1947 : Uganda Protectorate Geol. Survey Dept. Ann. Rept., 1947, p. 1—28. Uhlig, U., 1915, Monazit von Bom Jesus dos Meiras, Provinz Bahia, Brasilien: Centralbl. Mineralogie, Geologie, u. Paliiontologie, Jahrg. 1915, no. 2, p. 38—44. BIBLIOGRAPHY Ungemach, M. H., 1916, Contribution a la minéralogie de Mad- agascar: Soc. frangaise minéralogie Bull., v. 39, nos. 1-2, p. 5—38. U.S. Bureau Foreign and Domestic Commerce, 1918, Analysis of Burmese monazite sands: Commerce Repts., no. 170, p. 274. U.S. Bureau Mines, 1947, Monazite and zircon: Mineral Trade Notes, v. 25, no. 4, p. 14. 1959, [Bihar and West Bengal]: Mineral Trade Notes, v. 49, no. 4, p. 31. Uranium Magazine, 1955, Important thorium find in New Mexico reported: Uranium Mag, v. 2, no. 10, p. 26. Usoni, Luigi, 1952, Risorse minerarie dell’ Africa orientale; Eritrea-Etiopia-Somalia: Rome, Jandi Sapi, 553 p. Vainshtein, E. E., Tugarinov, A. I., and Turanskaya, N. V., 1956, Regularities in the distribution of rare earths in certain minerals: Geochemistry [Ann Arbor], no. 2, p. 159—178 [1960]. Vance, M. M., 1922, Sources of thorium in Ceylon: U.S. Bur. Foreign and Domestic Commerce, Commerce Repts., v. 2, no. 16, p. 186. Van Wickel, J. F., and George, E. B., 1924, Tin, radium, and monazitelin the Dutch East Indies: U.S. Bur. Foreign and Domestic Commerce, Commerce Repts., no. 35, 543— 544. Vhay, J. S., 1950, Reconnaissance examination for uranium at six mines and properties in Idaho and Montana: U.S. Geol. Survey TEM—A30, open-file report, 17 p. Vaz, T. A. da F., 1948, Metalogenia: Ouro Preto Escola de Minas Rev., v. 13, no. 6, p. 21—27. Vickers, R. C., 1953, North-Central district, in Geologic in- vestigations of radioactive deposits—Semiannual progress report, June 1 to November 30, 1953: U.S. Geol. Survey TEI—390, p. 202—205, issued by Atomic Energy Comm. Tech. Inf. Service, Oak Ridge, Tenn. 1956a, Geology and monazite content of the Goodrich quartzite, Palmer area, Marquette County, Michigan: U.S. Geol. Survey Bull. 1030—F, p. 171—185. 1956b, Geology and monazite content of the Goodrich quartzite, Palmer area, Marquette County, Michigan: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 597—599. Viswanathan, P., 1946, Beach minerals of Travancore: Sci. and Culture, V. 12, no. 1, p. 22—29. Wadia, D. N., 1941, The geology of Colombo and its environs: Spolia Zeylanica, v. 23, pt. 1, p. 9—18. 1943, Rare earth minerals in Ceylon rocks: Ceylon Dept. Mineralogy Recs, Prof. Paper 1, pt. 1, p. 3—14. 1944, Ilmenite, monazite, and zircon: Ceylon Dept. Mineralogy Recs, Prof. Paper 2, p. 3—12. 1950, Mineral resources of India; Empire Mining and Metall. Cong. 4th, Great Britain, Proc., pt. 1, p. 142—159. 1956, Natural occurrences of uranium and thorium in India: Internat. Conf. Peaceful Uses Atomic Energy, Geneva 1955, Proc., v. 6, p. 163—166. Waeser, Bruno, 1939, Kolonialchemie: Technik fiir Alle, v. 30, p. 130—133, Stuttgart. Wagner, P. A., 1918, Fluorspar: South African Jour. In- dustries, v. 1, pt. 2, no. 16, p. 1516—1520. Waldron, C. R., and Earhart, R. H., 1942, Bibliography of the geology and mineral resources of Montana: Mon- tana Bur. Mines and Geology Mem. 21, 356 p. 325 Waldschmidt, W. A., and Adams, J. W., 1942, The beryl- monazite pegmatite dike of Centennial Cone, Colorado: Colorado School Mines Quart, v. 37, no. 3, p. 29—38. Walker, G. W., Lovering, T. G.. and Stephens, H. G., 1956, Radioactive deposits in California: California Div. Mines Spec. Rept. 49, p. 3—38. Wallis, C. B., 1907, Liberia's minerals: Mining Jour. [London], v. 81, no. 3737, p. 453. Walton, Matt, Hills, Alan, and Hansen, Edward, 1959, Mobil— ity of granite in relation to metamorphic faciesmI, The Kalladar conglomerate, Ontario, Canada [abs]: Geol. Soc. America Bull., v. 70, no. 12, pt. 2, p. 1693. Waterhouse, L. L., 1914, The Stanley River tin field: Tas- mania Geol. Survey Bull. 15, p. 1—210. 1916, The South Heemskirk tin field: Tasmania Geol. Survey Bull. 21, p. 1—453. Waters, A. E., Jr., 1934, Placer concentrates of the Rampart and Hot Springs districts: U.S. Geol. Survey Bull. 884-D, p. 227-246. Watson, T. L., 1907, Mineral resources of Virginia: Lynch- burg, Va., Virginia Jamestown Exposition Comm, 618 p. 1909, Annual report of the mineral production of Vir— ginia during the calendar year 1908: Virginia Geol. Sur- vey Bull. l—A, p. 1—141. 1916, Zircon-bearing pegmatites in Virginia: Am. Inst. Mining Engineers Trans, v. 50, p. 936—942 [1917]. 1917, Weathering of allanite: Geol. Soc. America Bull., v. 28, no. 3, p. 463—500. Watts, Henry, 1849, On phospho-cerite, a new mineral con- taining phosphate of cerium; with observations on the separation of cerium, lanthanum, and didymium: Chem. Soc. [London] Quart. Jour, v. 2, p. 131—147. Wayland, E. J., 1933, Annual report of the Geological Survey Department for the year ended 31st December, 1932: Uganda Protectorate Geol. Survey Dept. Ann. Rept. 1932, p. 5—58. Weckwarth, Eugen, 1908, Los metales raros y su existencia en los minerales del Peru: Peru Cuerpo Ingenieros Minas B01. 63, 128 p. Wedow, Helmuth, Jr., 1954, Reconnaissance for radioactive deposits in the Eagle-Nation area, east-central Alaska, 1948: U.S. Geol. Survey Circ. 316, 9 p. Wedow, Helmuth, Jr., Killeen, P. L., and others, 1954, Re- connaissance for radioactive deposits in eastern interior Alaska, 1946: U.S. Geol. Survey Circ. 331, 36 p. Weis, P. L., Armstrong, F. C., and Rosenblum, Samuel, 1958, Reconnaissance for radioactive minerals in Washington, Idaho, and western Montana 1952—1955: U.S. Geol. Sur- vey Bull. 1074—B, p. 7—48. Wellman, H. W., 1948, Palaeozoic, m Wellman, H. W., and others, 1948, Outline of the geology of New Zealand: New Zealand Dept. Sci. Indus. Research, Wellington, p. 1—10. Wemlinger, C. A., 1950, Colorado pegmatite deposit yields beryl and mica: Eng. Mining Jour., v. 151, no. 11, p. 92—94. West, C. A., 1944, Ceria for glass polishing: Canadian Chem. Process Industries, v. 28, no. 1, p. 3—6. 37. West, R. C., 1952, Colonial placer mining in Colombia: Louisi- ana State Univ. Studies Social Sci. Ser., no. 2, 159 p. West, W. S., 1953, Reconnaissance for radioactive deposits in the Darby Mountains, Seward Peninsula, Alaska, 1948: U.S. Geol. Survey Circ. 300, 7 p. 326 West, W. S., and Benson, P. D., 1955, Investigations for radio- active deposits in southeastern Alaska: U.S. Geol. Survey Bull. 1024—B, p. 25—57. West, W. S., and White, M. G., 1952, The occurrence of zeunerite at Brooks Mountain, Seward Peninsula, Alaska: U.S. Geol. Survey Circ. 214, 7 p. Westerveld, J., 1936, On the geology of North Banka (Djeboes): Koninkl. Nederlandse Akad. Wetensch. Verh., Afdeeling Natuurkunde, v. 39, no. 9, p. 1122—1132. Wherry, E. T., 1908, Radioactive minerals found in Pennsyl- vania and their effect on the photographic plate: Frank- lin Inst. Jour., v. 165, no. 1, p. 59—78. White, A. M., and Stromquist, A. A., 1961, Anomalous heavy minerals in the High Rock quadrangle, North Carolina, in Short papers in the geologic and hydrologic sciences: U.S. Geol. Survey Prof. Paper 424—B, p. B278—B279. White, M. G., 1952, Radioactivity of selected rocks and placer concentrates from Northeastern Alaska: U.S. Geol. Sur- vey Circ. 195, 12 p. White, M. G., and Killeen, P. L., 1953, Reconnaissance for radioactive deposits in the lower Yukon-Kuskokwim high- lands region, Alaska, 1947: U.S. Geol. Survey Circ. 255, 18 p. White, M. G., and Stevens, J. M., 1953, Reconnaissance for radioactive deposits in the Ruby-Poorman and Nixon Fork districts, west-central Alaska, 1949: U.S. Geol. Survey Circ. 279, 19 p. White, M. G., West, W. S., Tolbert, G. E., Nelson, A. E., and Huston, J. R., 1952, Preliminary summary of reconnais- sance for uranium in Alaska, 1951: U.S. Geol. Survey Circ. 196, 17 p. Whitlock, H. P., 1903, List of New York mineral localities: New York State Mus. Bull. 70, 108 p. Whitworth, H. F., 1931, The mineralogy and origin of the natural beach sand concentrates of New South Wales: Royal Soc. New South Wales J our. and Proc., v. 65, pt. 1, p. 59—74. Wichmann, Arthur, 1927, Der vermeintliche Eruptive Quartz- lagengang von Passagem, . Minas Geraes, Brasilien: Koninkl. Nederlandse Akad. Wetensch. Verh., Afdeeling Natuurkunde, 2d sec., pt. 25, no. 3, p. 3—30. Wilford, G. E., 1953, Progress report: British Territories in Borneo, Geol. Survey Dept. Ann. Rept. 1952, p. 32—34. Willbourn, E. S., 1925, A list of minerals found in British Malaya together with a description of their properties, composition, occurrences and uses: Royal Asiatic Soc, Malayan Branch Jour., v. 3, pt. 3, p. 57—100. 1926, The geology and mining industries of Kedah and Perlis: Royal Asiatic Soc, Malayan Branch Jour., v. 4, pt. 3, p. 289—332. 1928, The geology and mining industries of Johore: Royal Asiatic Soc., Malayan Branch Jour., v. 6, pt. 4, p. 5—35. 1932, Report of the Geological Survey Department for the year 1931: Federated Malay States Govt. Gaz. Supp, p. 1—12. 1933, Report of the Geological Survey Department for the year 1932: Federated Malay States Govt. Gaz. Supp., p. 1—16. 1934, Report of the Geological Survey Department for the year 1933: Federated Malay States Govt. Gaz. Supp, p. 1—19. THE GEOLOGIC OCCURRENCE OF LIONAZITE Willbourn, E. S., 1940, Report of the Geological Survey Depart- ment for the year 1939: Kuala Lumpur, Federated Malay States Govt. Press, p. 1—52. Willbourn, E. S., and Ingham, F. T., 1933, The geology of the scheelite mine, Kramat Pulai Tin Limited, Kinta, Fed- erated Malay States: Geol. Soc. London Quart. Jour., v. 89, pt. 4, no. 356, p. 449—479. Williams, Gordon, 1934, The auriferous tin placers of Stewart Island, New Zealand: New Zealand Jour. Sci. and Tech- nology, v. 15, no. 5, p. 344—357. Williams, G. J., and Skerl, A. F., 1940, Mica in Tanganyika Territory: Tanganyika Territory Dept. Lands and Mines, Geol. Div. Bull. 14, p. 5—51. Wilson, A. F., 1943, A new occurrence of monazite in South Australia: Royal Soc. South Astralia Trans, v. 67, pt. 1, p. 38. Wilson, A. W. G., 1933, Preparing for the Imperial Economic Conference: Canadian Inst. Mining Metallurgy Trans, v. 36, p. 60—74. Wilson, E. D., 1939, Bibliography of the geology and mineral resources of Arizona: Arizona Univ. Bull., v. 10, no. 2 [Arizona Bur. Mines Geol. ser. 13, Bull. 146], p. 5—164. Wilson, R. W., 1937, Heavy accessory minerals of the Val Verde tonalite: Am. Mineralogist, v. 22, no. 2, p. 122—132. Wimmler, N. L., 1946, Exploration of Choteau titaniferous magnetite deposit, Teton County, Mont.: U.S. Bur. Mines Rept. Inv. 3981, p. 1—12. Winchell, A. N., 1900, Mineralogical and petrographic study of the gabbroid rocks of Minnesota, and more particularly, of the plagioclasytes: Am. Geologist, v. 26, no. 3, p. 151- 188; no. 4, p. 197—245; no. 5, p. 261—306; no. 6, p. 348—388. 1933, Elements of optical mineralogy, an introduction to microscopic petrography; Part 2, Descriptions of min- erals: New York, John Wiley and Sons, Inc., 459 p. Winkler, H. G. F., and Platen, Hilmar von, 1958, Experi- mentelle Gesteinsmetamorphose—II, Bildung von anatek- tischen granitischen Schmelzen bei der Metamorphose von NaCl-fiihrenden kalkfreien Tonen: Geochim. et Cosmo- chim. Acta, v. 15, p. 91-112. Wiihler, Friedrich, 1846, Ueber den Kryptolith, eine neue Mineralspecies: Annalen Chemie u. Pharmacie, v. 67, no. 2, p. 268—272, Heidelburg. Wong, Wen-Hao, 1919, The mineral resources of China (metals and nonmetals except coal): China Geol. Survey Mem., ser. B, no. 1, p. 1—270. [In Chinese, English summary] Wood, Harrie, 1882, New South Wales Dept. Mines, Ann. Rept. 1881: Thomas Richard Govt. Printer, p. 5—148. Woodward, T. P., and Gueno, A. J., Jr., 1941, The sand and gravel deposits of Louisiana: Louisiana Geol. Survey Bull. 19, p. 1—365. Woyski, M. W. S., 1949, Intrusives of central Minnesota: Geol. Soc. America Bull., v. 60, p. 999—1016. Wright, 0. W., Fullerton, H. S., Hulley, B. M., Carter, J. G., and Gannett, T. W., 1938, Mineral production and trade of France and French colonies: U.S. Bur. Mines Foreign Minerals Quart, v. 1, no. 4, p. 2—97. Wright, R. J., 1950, Current status of atomic raw materials: Earth Sci. Digest, v. 4, no. 12, p. 3—8; v. 5, no. 1, p. 3—10. Wylie, A. W., 1937, The ironsands of New Zealand: New Zea- land J our. Sci. and Technology, v. 19, no. 4, p. 227—244. 1948, Constitution of monazite: Nature, v. 161, no. 4081, p. 97. BIBLIOGRAPHY Wylie, A. W., 1950, Composition of some Australian monazites: Australian Jour. Appl. Sci., v. 1, p. 164—171. Yedlin, L. N., 1942, Standpipe Hill, Topsham, Maine: Rocks and Minerals, v. 17, no. 6, p. 206-208. 1958, The micro-mounter: Rocks and Minerals, v. 33, nos. 8—9, p. 418—420. Yoon, Suk Kyoo, Hwang, In Chun, and Chang, Yun Hwan, 1958, A report on the investigation of the Kosong beach placer deposits, Kangwon-do: Korea Geol. Survey Bull. 2, p. 189—218. [In Korean, English summary.] Yoon, Suk Kyoo, Hwang, In Chun, and Park, No Yung, 1956, Report on the exploration of the Sungnam fergusonite and gold placer, Chunan-gun, S. Chungchong—do: Korea Geol. Survey Bull. 1, p. 69402. [In Korean, English title.] Yost, D. M., Russell, Horace, J r., and Garner, 0. S., 1947, The rare-earth elements and their compounds: New York, John Wiley and Sons, 92 p. Young, E. J., and Sims, P. K., 1961, Petrography and origin of xenotime and monazite concentrations, Central City district, Colorado: U.S. Geol. Survey Bull. 1032-F, p. 273- 299. Zeijlmans van Emmichoven, C. P. A., 1939a, De geologie van het centrale en oostelijke deel van de Westerafdeeling van Borneo: Jaarb. Mijnwezen Nederlandsch-Indié, v. 68, p. 7—186. [In Dutch, English summary.] O 327 Zeijlmans van Emmichoven, 1939b, The geology of the central and eastern part of the Western Division of Borneo m Haile, N. S., 1955, Geological accounts of West Borneo translated from the Dutch: British Territories in Borneo, Geol. Survey Dept. Bull. 2, p. 159—272. Zeitschrift fiir angewandte Chemie, 1906, Monazit in Trans- vaal: Zeitschr. angew. Chemie, v. 19, no. 35, p. 1529, 1530. Zenkovich, V. P., 1960, Study of the seashores of the Chinese People’s Republic [translated by US. Joint Publications Research Service from Izucheniye morskikh beregov KNR: Vestnik Akad. Nauk SSSR, 1959, v. 29, no. 9, p. 76—78]: Internat. Geol. Review, 1960, v. 2, no. 4, p. 354-356. Ziegler, Victor, 1914a, The differentiation of a granitic magma as shown by the paragenesis of the minerals of the Har ney Peak region, S.D.: Econ. Geology, v. 9, no. 3, p. 264-- 277. 1914b, The minerals of the Black Hills: South Dakota School Mines Bull. 10, 250 p. Zodac, Peter, 1937, Minerals of the Strickland quarry: Rocks and Minerals, v. 12, no. 5, p. 131—144. 1941, The Andrews quarry near Portland, Conn.: Rocks and Minerals, v. 16, no. 5, 164—167. 1953, The sand collector: Rocks and Minerals, v. 28, nos. 1—2, p. 56-61. 1958, Xenotime-monazite sand from North Carolina: Rocks and Minerals, v. 33, nos. 7-8, p. 311. UNITED STATES DEPARTMENT OF THE INTERIOR ‘ PROFESSIONAL PAPER 550 GEOLOGICAL SURVEY _( ,3 ~~ PLATE l 00 ° 0 o I o o 0 75° 15 30 45° 60 75° 90° 105° 120° 135° 150 165 180 75., .3, .1 o blillcyko Sibpifi -! s M.Ulcs M.Shanlsa ®\j O S d P ‘4‘ ' 00 P h h . KjM Medvezhiy Derevyannykh .Nadezhnyy \\ ‘ 7. . ‘ ~ ' A i r 3 ml em a ‘ Q Bjornoya . “ M.Vil§ulova . Vei' l'upé7 )V.Mlnll’&a}‘ // 6 Y PROLIV SANNIKOVA Cor \\ M.S f” _ 0. B ' h lePOVOgO K A R A Pyaslnskill.s \\ Q eglc 8V3 0' Stolbovoy \ v Pal’tsev 0<> .._..,.’ *3 I’ . 0. Malyy Lyakhovskiy \\ Mys Sukhoy Nos :2 PETER/KA ‘ \ . . \ . 0.1 il'kiiskogo . . 0. Bolshoy Lyakhovskiy IBER AN \ B A R E N T S S E A S E A M.Ragozina Beiyy (,9 0 5‘ . Pov. Kigilyakh EAST S I \ 0 Pl? M.Shuberia It: {31352; I \ 7A M Sk OUV PROLIV DMITRIYA LAPTEVA - \ ‘“ M,Stolovyy ' uraiova M.Maiie-Sale Mys Svyatoy Nos \\( SEA \\’7, in Mys Severnyy Cusinyy Nos \ I 15h”:- Z l' Khra'ms ‘uya x \\ “"8 ”’0an k (“”7“ j/L lys Lopatka 0STROV VRANGELYA \ we?" . i am ‘ : ’ Osti\ov Geral’d Mageroy go‘ M‘Mezenina ’~ ’11-, M,Florens \ V Y k l k K , , I . .Litke \ 6 0V eVS aya 053 (I l ‘ ’ _ \ _ Sharapovyll , ' ‘ ‘ a a q Ostrova Me ivezhi My5 Blossom \\ . Bolvanskiy Nos K051]le “' 1°40"\ Mys Vankarem .5. @333 35 -~\/ ,.2 o W 0m" \ I \-.\ .' , I 4 POLUOSTROV 35.25. ..-.. ..-_/ l ' ,l . Mezenskaya G. LYUC-lAiONGOKTON - \. alum l R h L Eiiiiii~ _i iiiii ==§-.—- BELOYE MORE Q? ‘ ANADYRSKIY 'l/ ZALIV Mys Chaplina ,’ Stl’Lawrence / // /l I ’x // i / / ZALIV SHELE’KHOVA Mys Duga _ Vina Mys Yuzhny ’ BASHKIRSKAYA ' ) If \ \I Kama (I 7 SEA OF OKHO SK strova Komandorski e l I ' RuSSKAYA . .R. /* )9. Osirova y Q/ ’ , . TATARSKAYA , \ _ E , l c)” /\/ T A.S.S.R. \ l awmniarskiye \X /l // («v f I , y , _ \ / I 9 \ /f ‘I ~ / / $ //////NALEUT ng)?’ /\ sews/j l l/ l/ Attul E413 .1 I A N E is l / < Shem "' ‘9 “$9580 Atka I ,IP‘J // \\<2.q q‘Agamii' Klslgl. 0 an {5" _.." w p ./ I ‘ ~° . .12) I’" f «-1 I ‘\\.4j\ NU HOKIANG ,1 . $9 . . . ‘ U M A N I A s ' . 11‘ A . i' a“ iav" 4 (EV; \- it zero Balkhash \ UruPPu T270‘2’CO '. / K a 'I . 45.. ‘ . . “<3 .Jx» . . W 0A M 450 , , . \( . x W ' E ” I LIAOPEKI-Iv") m {I l V @t'oéli’fu T0 ‘ . if“ r. A CHAHAR /\ [J \ V. ‘ , una. JII‘I . im YU G O s L A V I A\ Danube DAG STAN, . W . a .4 r < K'1 I. ' HOKK ”9 " ‘9 / BULGARIA IfoKA A.S.S.R.\a I , " " s - . ' ' K ‘ V“ J / AIDO a ADRIAYHC “'1 ‘ yAis s R , 'i s. I I ,J‘J\\.g§’ — xiféfk I; r i'\ \l ,EHOL f: 5 EV v comic ‘ SEA i/V \i i i i ‘ I L i /;7 KIRGIZS AYA 88 R )I O ’2. \‘ \‘I fl 3 ”Pl” ANTUNG 2 V ”W ‘ koaureyl ' ' '/" // SU \\ """ ( SUIYUAN \ J/JLIAONING‘: 12 o vx, NJ , , ~ ) , a” Tip» My 5 ’ N K ‘ A N G b I W '\./’”l NINGSIA ‘ .t.’>~\C/‘x./A 126T , , .-/ _/ I , _ I an... N «,/ so ( I 4 I JAPAN ANTARCTICA .. ~\ (\I ~—~/\.p. .J \ / . Ix, / TURKMENSKAYA .S.R. I VI” I ,__, A.\ \./, ,/ Q D \.\ RI TADZH I KSKAYA {J ,fl‘” “-vT‘J "\K ”\5 3 I V \ , ‘ . «x "‘ (—CJ“ \r. ’ SSHR ’ \. 1 / ‘ , WEE: ’ “a Q" l C “ I N’s. A ’ l A‘s/Cl “ — N -/ :3 ILL'L/ » .. 4 _ \ I A \. , f l’ . a $ I .‘ /.F‘\.\/ _ \,\\ \ \ X 0% r g / \«/ \l 1’ Malta 6 ~ « A / ’1 / TSINGHAI 7’“ ‘ vi % .. Karpatho )V.\ / / . / F7 . Crete l / exRJSfiENSl C. ‘1 l I .. 2 MEDITERRANEAN S \I V“ we- .2 “i 2 Wed . ,l ‘2 I‘ ‘ . \ w 5 Max}, *\ a I ‘\./\,/\,/ ,ZiJ‘IJ\/i\ KU VHaChIJO'Jlma a «f \\.a ,/ \ f V” ‘\. k ,l K \-J‘\ I" ‘A°ga Sh‘ma 6 M \w / \ T I B E T , filKANG x}; l SZECHWAN \_\\ S . J. NANPO \ ' l\ l. YN~ \‘1 / «fin/ween I 6 \ / />1 ‘3 umlsu ima a l \\ ,I 4, \_‘ J) \\ ran! ‘ ‘ ’Q ‘.' ' Yamome Iwa ‘ i 0 A L G E R I A W “m ’ 5 l I Z“\ 61° ‘4 MTzzl/ERZEST Ale“) {’5}, ~29 - ~ ) L I B Y A I .~- 4 1 “mag-Mi /' "i Ii ooi‘ .G t_ OGASAWARA GUNTO M / \r' . mami un O , I“ .‘ ‘i i UNITED \ I77 HUMAN ' N‘Shi’w Shima- :Chichi Shima . v AB V ‘8 . - ' ' ; In :/ | AR KWE|CHOW , “v, , . .. gmdnawa Gunto Haha Shima ‘0 I I REPUBLIC _ I ./ 2 40 38 6e . b \ I l , ad's/’5 [A 025/47. ,J . . $6 KAZAN -Kita—i6 Jima rt: q, \\ I D My! 29 O ‘27:,M ”WA“ 3 - . RETTO ’15 Jim 90° 5 Ln 7; _ _ _ __ S_ A _H_ _A_ B _A)\ _____ TEOB‘EOEE’LNCEE , ' ,,,,, WI KWANGS'efi (3’28 l “mm-‘5 Jim E”? a X z/ \ ,’( \\\ A“ 3 ' H I ’. ‘ 1 \ ‘ ‘\ l fl“? 3 use 0 P ’I ‘ ~ x .. .——-————— » ‘w cs - m ' BYRD Ix 85° .6 \ / l \ E“ co $7 Cl STATION» 2 \ ," ‘\ \‘\ l Al Mlfisirah 31 O F 11 d P ' (l a " i I l: 1,‘ ’l/ ) ~s\ r—‘I a A R A Gulf .-Parece Vela ' . figuognlse all“ 5 U1 1 6 v L _/ I ‘J of _ LUZoN ° . Babuyan Is ' Asuncion I v) o 1 _ ’l l l Hal-nan Tao , A rnu", I '7 (D ,,, . 8 '\ I | S E A \ Tonkin Cape Engaiio . 'Fg I {5le ’I/ ' . agan “' i \ Hm I .. ' ’, NIGER i : S 0 U T H Alamagan I Buguan I "I LilTTL‘E’” I, l l l Luzon _.Sarigan I 120° AMERICA 120° . «0 PHILIPPINE SEA STAT'O” 75 "’ INDO‘ S 32 ($2 Tinia I .SalpanI 80S w “A 7 B“ 13?“) Row? 'Agu‘lanl S SIlJA , — 15° C H I N A .- . - HALLETT CHINA Mindorim , \ . 6‘ dGuam STATION .. D , ' I fro P s- Suqutra lg - -.-. Capo Cuardafui . . ' . ;- >~ :, S E A Ronny _ ".- \P . LACCADIVE IS..:‘: I ' 4&9 a D Q Ulithi Atoll 150° 150° . 9&3 {‘13ng Yap Pals I 65° . . ‘,- a", S U L U S 1A 11 ,Faraulep Atoll , 180° ” Mimcoy I - Balabac I a. indana PALAU ‘ No to . ’W Fayu A101 [CENTRAL ‘. (03‘ ’0 S E A IS a WOIQai AW“ ‘ - Lamotrek Atol _ MALDI E , '10 E ' ‘k At 11 AFRICAN '4 V 15 ”L14 - -‘ 2» O 4 1?...an 0 ' ' . . s’l‘awiiawi Group -Sonsorol I; O 0 300 600 NAUTICAL MILES ‘ . , Great Pulau Pulau Tala’ud 9" P96 'P_‘11° Anna L I N E I 3 Fernando E50 0 . 9 N31?“ L 'E B E S \ \ Peg T b' I . III, I. Pulau Simeulu'e E A Sangihe r. 0}? O 1 ' xMakin Atoll GULF OF GUI’NEA‘ '. . Puiau'ruangku: n ‘ S - V00 0 Abaiang (Mmkei G I L B E R T . ‘ " . ~ ‘ 0 Asia Eilanden . . Tarawzi Atoll? . . . Suvadiva Atoll Pulau Nlas% ‘ W 6‘ @Halmaher’a ,IMjpia Eilanden . Kapingamarangi Atoll . > Howland I D 350 Tome/0.. , E Q u A T O "-R o- . = ~, E O U A T o R Maiana ,AbemamaAtou I s L A N D s -B k 0 i I . ' Pulau Pulau BuLu . ‘ d Waiven 3 er I 0 Cap Lopez; ._ . '- Bf . ‘ MOLUCCA \. €74 Biak Nauru Island, Kuria 0 ’ i i "I 147 ’ Pulau Siberut . F 6 V3 - , 0 I“ \Ai'anuka 'Annobon’ . ‘ . O Q ago SEA & .. _ Japen . > = Admiralty ls s M2553“ “93“ J . \Nukunau . ' 4'. é» . - .W , .<. V: M ’ 0 t . Beru 9 RE BCL PEEGOF TI-IIE Pulau Pulau IVlenlawain§ Pulau Pulau Sula M15001 anuibo‘". . Q _: _ T213: . Kingsmill Crou ‘ . ‘ .‘ » .. Buruq jvm 5 BISMA " ' ‘ . ii I S ych'elle-S‘Ci-‘Oup _ Chagos Archipelago -B J: I _ i‘ ‘ RCK ARCH New Iiéeland.I I ! McKean Island . .ll 9 o o - an a Si“ '. 0| ., ’ teen 5 8:“ S =’ Gardner Island _ .‘ 60 75 , 90 33311 B’utung BANDA SEA Pulall l’ulau Kai VV k - _Q<::fl 1‘... N At ll ELLIC Hull Island l.’ . 6 0 am SO anomea o . E \ .» ' Alphonse I" 122. Breede River 27. Fu-ch’uan hsien, Kwangsi Province __ .. . _:~ .' la FLORES SEA . . '. To mor§giARU IS New Britaigugamwuel a. X. 051401», Nanumanga I- ISLANDS \ » _ 123. Sub Nigel mine, conglomerate and shale 28. H0 hsien, Kwangsi Province " I _" " “ ' " pulau Watert? .. fianbag Ia tfluiarjigszlu Frederik Vella Lavellac} Sarita Isabel I Nul AW" . \\ “ . . 124. Witwatersrand area, conglomerate 29. K’ung—chen hsien, Kwangsi Province ' imwcfi'w ° ‘ 'fi'i ‘ M' ” Tanlmbar rial??? 9‘Q%, \ ‘ Stew“ 1‘ ' F "an", \O A f . ,- 125. Vlaklaagte, accessory in granite; locality 60 to 70 miles north- 30. Eastern Kwangsi Province " 8&1), - u a“ 08 la “1 -,., . New Georgia - . d I: 3“,,an ' H \‘V t“ " ' ., s». 'Alduabra Is t f P t . H b k f . . . _ . Lombok Sum awa Flores 1 ' . 0Q - fit G d l 11 4 -Nukiilaelae \/\ , Cosmoledo ,mup_.._, j. eas 0 re oria, outen ec arm, accessory In pegmatlte 31. Kwantung Provmce, littoral sediments <5 ““0? n I .5 .f M “a “a“ Q - 4» . Dun is _ \6‘ I 98 ~’ 126. Enkeldoorn, granite . . , 32. Chin—men tao Su'f‘ba .- “<7 T' S A R A F U R A S E A 0 ’5; ’Ciirork 3... =,. .2, S O L o M O N k 9 . \(41’ lie. 30mm Cap.d’Ambre 127. Zoutpansberg dlstrlct. Bandollerkop, also accessory m granlte 33. Coastal islands of Fukien Province ““40“ ”m” e“ , . Cobourg Pen- 2 a San Cristobal I as?” 0"“ 1’ N mi... \c .. l \ ll ' 128. Barberton district, granite 34. I hsien Ho—pei Province Me "‘1“ [19(3) = "C.Wessel . _ In. S E A .Q , . , \ i , lg. ~__ ~\ . I: Q 129 S d . 8 .1 h f S d 0 h k . . i . 35 Louisiade Arch. Rennell I R \ .\ "J .- k . an spruit mi es sout o ' teyns torp near s be ,granlte, 35, Coast of Shantung Province G If f 36 6%) Torres Is - °tuma I \ . . .q7 also accessory in pegmatite and In fluVIal sedlments 36. Coast of Liaotung Peninsula C T 1 u o / v; ~ 2,; ., Banks 15 I)“ wan“ - 52ml FEDERATION 0 130. Waterberg coal field, sandstone 37. Heilungkiang Province, Manchuria ' a W “a . A 2'. ‘Tles de Horne \\ ms 150 N RHODESIA AND 131. Springbokvlakte, sandstone 38. Chienchowtze, Tanshui hsien, littoral sediment; Chi—lung Tao, 150 l D carpenmr'“ C 0 R A L (\ . .4 \ 15° 9% NYASALAND 132. Witbank coal field, sandstone Taiwan, fluvial sediment I I , Sp‘rlt‘llu all) E FIJI vNiua F503 6:21. 133. Harrismith, Kestell area, sandstone 39. Kuanyih, the Nan—k’an ch’i, T’ao-yuan hsien, and the Hung— ' S E A Sliililgkulafiq 2 " I l . : . _______ \ " 134. Durban, Berea Range, Umdloti Beach, mouth of the Tongaat mao chiang, Taiwan Dampler Land -» NORTHERN 5 a ,» Malian“ Lev“ l , Cabo Frio 2” River 40. Pen—tzu-chiang, Hsin—chung—li at K’an-t’ou—tzu, Taiwan “3‘5 o 9% Viti Lewes . I I , 135. Mthamvuna River . 41. Miao—li hsien, Houlung hsien, Taiwan TERRITORY Eromanga Ia _ . . i ’ Vavaiucp l REPUBLIC OF THE CONGO (LEOPOLDVILLE) 42. T'ai-nan hsien, Yun-lin hsien, T’ung-Shan Chou, Hai-shan chou, ,- Tana Q Trimming a6 . ‘.-.- TONGA 15“;le l 136 Sh' k 1 b K 1 . 1 fl , 1 , Wal—san-ting chou, Wang-yeh—chiang, Ch’ing-shan—chiang g “es B819? ~' i1 U 0 i I ' . - I Palgrave Point 137- Y 2nk09 11151931 35010: a 50 UVla sedlments Shan, Wang-erh-liao Shan, mouths of the Pei—chiang ch’i, g; e Avea ”Aneuyum Ono-i-Iau , I 13 ‘ I? 0 we, h' 1R? Ava Pa—chang ch’i, Taiwan K; ~ 1“{°“Q>.ILALS LOYALTY s; l 133' Lafanias 1 lV‘j’r , 1 d' h N N K _ , 43. Pei-chiang chi and tributaries including the Houkoutze, Yen— North West Cape Chesterfield New Caledonia Elle Tm Tongméu GP I TROPIC 0F CAPRICORN ' uRiljerswer region Inc u lng t e ange- ange and atepiti shuinan, and streams at Hou-liao, Wan—lung; the P'o—tzu ’ unis .Ile Walpole ’Ata I . . . . chi and tributaries including the Liang ch’i and streams at ‘ 59% Group T R IO P l C‘ O F C A P R l C O R N I — — — — T - ‘ — T: ”T — — — —» — 140. Maniéma District Lin—nei Weitzenei Taiwan " — ‘ ‘ * ‘“ “““““““““ S “‘ : i i i i w ————————————————————————————————————————————— IT 1 .\ 5' 141. Uele River 44 Pa chan ’ hi' , ‘ - - - I- I 3' _ . - g c i and tributaries including the Shang-ta chi, a I ‘ V . fig gurbaleiéerR L k R’ stream at Tung-kuo, and the Totzetou; the Ts’eng-wen ch’i C'Insmplion l ' . S a ITFTL‘E’ R ml CaP salme‘Ma' 144' TolmCP'aH 1 iver, 0 0 lver and its tributaries including a stream southeast of An-yeh, \ ~ ’ l. . ,..,.L.L L _ , z} 145' ”if; Elli/:11“ the Sutzu, and a stream at Yung-lo, Taiwan Steep PL 0103 q 5 i :ll ' 45. Hua-lien ch’i, Taiwan J ‘ 7 ml .~ . 146. Poko River TR; DJ I H I: 147. Mompela River FEDERATION OF MALAYA fl WESTERN‘51 ' QlAUSTRALIAR I 3' 148. Sill River. . ' 46. Kuala Trengganu, Sungei Kemaman, Bundi, Trengganu and 86 55%;: .. @P “:"F’I “.2011, 'PhilipI i 300 . 300 149. Tayna River, Mohanga River, Lutunguru River border with Pahang 30,, 1% 331133 3 l SOUTH Kermadeci, l REPUBLIC , RUANDA'URUNDI , _ , 47. Baias Tujoh in the Kampar district, Perak ‘° :2 | m -' l 300 150. Rukarara River, Blnana River 48. River Kenring at Puchong Babi, the Sri Muka, fluvial sedi- x884" “ T>3E3 6; l g l " .M... 0. is Eligisziiiiiig‘gafwm .9 m m . - 92 7597 I . . , . ungel arangan near u 1m in e a , granite; caSSIterite- , 1’0"” SOUTH AFRICA . . ' . y . . _ . ' _ . SIERRA LEONE quartz veins; fluvial sediments 109 ,Dcffilt l O 30. Lufirl River near Sallmu Village, LiwaSl River northeast of 50 Dindings G | K l ‘ R' 153158. See late 2. ' 108 .. ' real Australia 3' ht 1 . 31 Chisliltg-nslg‘glamlver MALI REP BLIC 51. Ulu Sempam, Bentong, Raub area, Pahang, Kuala Selangor CapeLeeuwin ‘ 'C-Paé‘ley n 29 Cape Mari‘a : Care AsfllbfiS. 32‘ Z b .11 SO U Swamp near Bukit Ginting Prah, fluvial sediment; granite lead C'Ca‘as‘ml’l‘e '~ Van Diemen I 0.11,, ‘_ ,s . 33. Nazikviavhraeie 159. Giuba River 52. Sungei Badang, Gambang, tributary to Sungei Kuantan, Ulu Was I €03, I ‘ - . ' ’ ,, ~ - 160. Lugh Ferrandi, Monte Curetca, sandstone Sungei Reman, Anak Sungei Chereh; Sungei Bakah; Sungei 105 T A S M A N ' ' . l . Go ‘ 34? Port Herald, Shire River 161 Scidle sandstone Anak Reman' Sungei Reman' Anak Sungei Reman Sungei 'Q‘G'eat Bamer 1- l 01) H ‘ 35. Pal'ombe plain between Lake Shirwa and Mlanje Peak ' ’ , . S l - l . - ' 120° . I ‘ _ . OH: 162. Bur region, crystalline rocks angka Dua, Anak Sungei Panching, Ulu Sungei Pandan, Green Cape l O _ 1 D " ’ GHANAI 163. Bardera, sandstone Sungei Tulang, Sungei Belat, Sungei Badang, Sungei Gam— 69 S E A Em (ape | Q . y . , 5 36—54. See plate 2_ 164, Dola region, sandstone gangk; :uklt'BTeserihkAnak Sungei ghil‘nl Sungei Taweh, 112. Changp’y‘dng—ch'b’n, Pongyang-myO’n, Chech’En-gun, Chung- 70 l ‘ . .‘ I 165. Laferug, Daarbuduq, Berbera District na ungel awe . uantan area, a ang, granite; sedi— ch’ong-pukto .‘ KENYA mentar rockS' fluvial sediments ’ "’ T I ..~ . . ATlON _ ‘ y , . 113. Koesan—gun, Ch ungeh ong—pukto . . | . v i EXPLAN ,_ a . , .I . . 55, Loldaika Mountains-Ngare Ndare area SOUTH WEST AFRICA 53. Kinta valley at Pulai, Ipch, Papan, Selama, Rotan Dohan, 114 Yon un -m 5n Kae I -m Vn K hIV V Y hIV V mug/L? 66‘55 fiFumeiux GP- l The symbols- show .the reported location and mode of occurrence .of 56" M . H'll 166. Erongo Mountains, Omaruru area Perak fluvial sediment- granite and aplite - gg g y o’ p (3‘, YO 3, amc ‘Bn—mYOnI ec on'ldp’ 68 r, ,9 I . - n . . ~ ‘~ mb 1 . ears i ’ h “L alit - . rima 1 . . . , , I I Yongmun—myon, Yuch on-myon, Yech On-gun, Sanbuk-myon, ’ N E w | monaZite..lTlIe.lnu,mll‘ler oppos1te a sy o .app n t e 0C y 57 Mouth of the Galana (Athl) River 167' U15 54; ngkflv Johore M ’ P’ ‘ " Y" ' K “' index”. The numerical order in the “Locality index" follows the pres- 58. Mouth of the Tana River 168. Brandberg 55. Ulu Sungei Payong puiiTlogyong—gun, unggi-myon, ongJu—gun, yongsang- i entation in the teXtI‘except that closely adjoining localities, Wthh for I . ' 169. Neineis, Omaruru River 56. Pulau Langkawi off the coast of Kedah and Perlis . v v - . -- -- , m l geologic reasons may. be discussed separatelyyin the text, are included 59.,Patta Island 170, Ebony 57, Kelantan 110' Kozong ”placer arfia ”including” Chumun'lin, HwaJVmTP 9’ TE, Z E A I. A N D I under onesymbol'onfithe map. The ’spelling 0f place names accords W MALAGASY REPUBLIC 171- Kranzberg, cassiterite 58. Sungei Betong near Langkap Negri Sembilan, granite" Ser— Cfinfinung-gun‘,’ yémnam-myon, (”lg-1:1", K'onghyonli-ri, IA l with usageof the.U,.S. Board on Geographic Names if decisions were . . .. 60'..Antsaonjo 172, Visrivier emban, fluvial sediment , K u ‘vvanngyonkuuangyailéngun, oaJlngllll’ Panuam-ni, o o . Chatham ls l available. Place names for which no recommended spelling was available _ ‘ 61:“ Anal-abe Berohitry 173. Orange River 59. Sungei Bisek Sungei Lemoi Pahan aBSOHs-myom 0J1n'n1. OJlm-my0n.u angprOng-n’l, 135 150 3:1,. I . - . . . . - . : , , , _ - , , I 3 g . . _ . Chodo—rl, Chaltong-ni, MusongJong, Hyonnae-myon, KO- - | are given as they were In the original SOUrceS used for the text. .. ,62. MananJeba SWAZILAND PROTECTORATE 60. Slak near Siputeh, Batu Galah, Sungei Slput, Jalong Tinggi sdng-gun Kanng'n-do 45° 1 4 o ' . . s 63. Marotolana b b. Estate, Sungei TGI'J'OII Sungei TGknahy Perak 116 Chinbong—rnydn Kaesb’ng—gun Kygnggi—do 20. Brunswick Heads, Cape Byron, Broken Head, Lenox Head, 1 5 .3“ O ' ' ‘ ' 64. Between Miandrarivo and Mandoto, betweenrAnkisabe and 174' M a dim . i . _ Iv ' _ v ' Iv _ v - Seven Mile Beach, Ballina, New South Wales / . , , , . . 175 Komatl River north of F b s R f INDIA 117. Sutnae ch on, Chungdae myon, Kuch on myon, KwangJu-gun, . pu .56.,“ / Monazite occurrence in unconsolidated and poorly Soarlvola, Ambatofots1kely, Ampandramaika-Malaklalina 176. Mhl t R' 1 5 ilor e thee t f K b t . . 61 C . . KyOnggi-do 21. Clarence River, Yamba, New South Wales ’ D // . ' . z v r . . - ' . consolidated sedimentary rocks area . a u ane l e mi es nor W93 0 u u a 0352:. 0f Kerala, Inelllidllng consolidated and unconsolidated 118. Ansdng-ch’b’n, Songt’an-my‘é’n, P’yO’ngt’aek—gun, KyO’nggi—do 22. Wooli, New South Wales Qu/ Mainly beach and stream deposits ochcent age; imcludes 65. Ihorombe-Ambararata area, upper Belobaka River, Manat- TANGANYIKA 5‘3 iments at Vark al 1 and AnJengo, and unconsolidated 119 Coastal islands including Yong u—do Yon hfin -m an Pu- 23- Woolgoolga, New South Wales / residual deposits sahala River 177 Uluguru Mountains Mikese area of the Moro oro District sediments at Manavalakurichi, Muttam, Neendakara, Kal‘ i ch’O’n— un Kan hwa—do Sb’iiwb’njm 3mg K g hy I 24' Laurieton area, Perpendicular Point, Diamond Head, New Sn > Bounty IS . "\I’ 66. Itrongay 178. Ukaguru area ’ g lada River, Ashtamudi Lake, Chavara, Tiruvellauram, Ku— KyO’ngggi do g ’ y ’ ang wa-gun, South Wales ar 48/ X 2;. 1134:1413: Vonambohitra 179- Rubeho Mountains rfiggalillzirirra, Kodinuna, Pudur, mouth of the Valliar River, 120. Haewdl—myb’n, YOnbaek-gun, Hwanghae-do 25. Svsgéi‘svegjll‘fla {gelluiing Catherine Hill Bay and Caves Beach, 037 ' ' ‘ - ' . 1 . B l‘ H' . . _ _ V _ I U _ a e . / MonaZIte occurrence as an accessory mineral. In con 69. Andranomalaza stream, Baie de Sahamalaza 80 unda 1 Ills 62. Cape Comorin 121 Sun an,yTongam myon, Pyongyon gun, P yongan 113.me ' 26. Terrigal, New South Wales Annpodes ls . / solidated sedimentary metamorphic, and igneous . , . 181. Songea 63 .1 122. Pongch ang-ni, Pongtong-myon, Kusang-ni, Chungsang-ni, . . ’ ‘ - rocks I 70' Ambahy, also granite gneiss 182. Wigu Hill on the Mgeta River near Kisaki in the Morogoro ' Qul on . . Pukch’ang-mydn Taepy‘o’ng-ni Unsan—mydn Happ'o-ri 27' Bellambi Beach, Port Kembla, Bulh’ New SOUth Wales // . . . . 71. Tongafeno Betafo, Ants1rabe, Anpangabe; also Quartz vein - . , l 64- Amod, Narbada Rlver on the Gularat Coast v I v ' IV I I v l - ' 28- Shellharbour, New South Wales 4Au‘3kland Is ’ Includesfosszl placers; excluswe ofoccurrences on bodies 72 M DIStI‘ICt 65 Ratnagiri Wont an—myon, Sunch Oil-gun, P yongan-namdo, fluvlal 29 Sh lh R. N // of pegmatite, veins, and carbonati‘te masses ' orarano , . , 183. Locality 30 miles southwest of Masasi, metasediments ‘ deposits pegmatite ' 03' aven lver, ew SOUth Wales 73- BBfanaInQi MlarlnkOfenOI Maharidaza 184 Locality 16 miles southwest of Tuku ii 66' Mormugao 123 Chajak-ri YPuk—myo’n Pongtong-m b’n Kaech’on- un P’ O’n- 30' Narooma, New SOUth Wales . 74. Ankaditany, cordierite lamboanite 185. Mpanda River Uruwira‘ also accessiir in sandstone 67. Gulf of Cambay ' an-namdo ’ y ’ g ’ y 31. New England area, New South Wales, granite and pneu— . . . 75~ Fort-Dauphin, granite 186. Kabungu Hill I I y 68' Coromandel Coast, Madras 124 Sii—ni YO'n wO'n-m 5n de wi‘in- un P’ On an-namd matolytic veins ”CampbellI MOUaZIte occurrence in pegmatlte 76. Ambatoarina, metamorphosed limestone 187. Mk t Pl - 69- Chllka Lake 125' K d, g. yu ’ U i“, g ’P’ l: g 0 32. Hastings River, New South Wales, sandstone COMMO’LW “3 mm"? accessory mmeml 77. Presqu’ ile Masoala, Maroantsetra, Baie d’ Antongil, fluvial . a a ains 70- MOUth 0f the Brahmani River, Qrissa 126' Climl- ong, liliuLmyon, Sir? on-gun, yongan-pukto 33- Manning River, New SOUth Wales, sandstone A and littoral sediment; granite and schist UGANDA PROTECTORATE 71. Visakhapatnam, fluvial and littoral deposits; Waltair High- 127' Infifisrim-‘riurdh ggggfighpli uon Ham O'n -namdo 34. Hunter River, New South Wales, sandstone ' ' ' 7g. Mananara, Pointe 5,1 Larrée, fluvial and littoral sediments; 188. Northwest of Mbabara near Bwizibwera and Maseruka, lands, Padmanabham near Bhimilipatam, gneiss; Errada, 128. San "ii-dd/n waafhae—igdn ,Pur 5§y_ ugn Ham 5n _ ukto 35. Pascoe River, Cape York Peninsula, Queensland MonaZIte occurrence in vein granite Rusangwe River in the vicinity of Mbuga, Kitomi River to Gangavaram at Malametta, Kutukonda, Uppeteru, Vada- ' g.) g, y ’ y g g ’ gy g p 36. Hey River estuary near Weipa Mission, Cape York Peninsula, A 79. Fenerive, Vavatenina, fluvial sediment; kyanite gneiss and the east of Marangara, Kyamutanga River, Bwizibwera mutupalem, Pudimadaka, Kothuru,.Lemarti Agraharam, PAKISTAN , Queensland 165° 180° schist . River, Luhagura River, Kinyamatehe River, Kanyambarara Turkhodapalem, Konavanlpalem, Kailasa, Andhra Pradesh, 129. Indus River at Amb, Hazara District, West Pakistan 37. Cairns area, Cape York Peninsula, Queensland Monazite occurrence in carbonatite 80. Ampasiriamloo region, Ampasary River, fluvial sedlments; River. Nkurungu River. Kitagwenda River httoral depos‘ts . . 130- Hunza River 0-5 mile “PStream from Gilgit Riven WeSt 38‘ Russell River gOIdfield’ QueenSIand Western Australia ' 9 granitic mlgmatite, kyanitic and sillimanitic gneisses 189. Buhwezu 72- Mouths 0f_ the Godavari Rlver Pakistan 39- Walsh mineral field, Fingertown, Queensland; also wolframite _ . Q . 81. Mananjary River, Saka River 190. Kabale River near Nyakishenyi and in the Kigezi District 73- Nlegapattinam 131. Cox’s Bazar, East Pakistan veins 83- Yllgam goldfield especially at Southern Cross, gneiss . . 82. Mouth of the Mananara River east of Vangaindrano, Rano- 191. Igara 74. Tinnevelly area, Gulf of Mannar. PHILIPPINES 40, Tinaroo mineral field, including California Creek, Emu Creek, 84. Pilbara goldfield especially at Nullagine, conglomerate MonaZIte locality mainty UNITED ARAB REPUBLIC 75. Tadlkarakonam, gneiss; pegmatite' , .. Nettle Creek, Bamford, 0rd, Coolgara, Queensland; 3150 85. Wandagee, Minilya River, Wandagee Hill, sandstone and shale Mode ofoccurrence unreported 83. Manangotry, Vohimena, granulite and granite _ . 76. Kuttakuzhl, Cootykad Pothay in Vilavancod Taluk, Vellanad, 132- Nueva E0113 _ greisen 86- Irw1n River, sedimentary YOCkS ______________ 84, Ampasimena i3: BeltitOf the N116 Rlver Esanlthimangalam in the Thovala Taluk, Kalkulam Taluk, 133. Paracale, Ambos Camarmes, Luzon 41. Wallaby creek, Arman River tinfields, Cooktown district, 87. Donnybrook, sandstone . 85. Vatomandry, Manakara - 05‘? a era a REPUBLIC OF INDONESIA Queensland 88- Gingin, Poison Hilligreensand International boundary 86. Manantenina—Baie des Gallions area, including Bofasy, Ilana— 194' Damietta 77' Yadiur near Bangolore, Mysore . 134 Dendang Belitung 42. Mount Isa, Mica Creek, Queensland 89' Hillside, Tambourah mainty, Ambalafandra, Ambinan’ Andringitra, Vohibarika, 78. Bangarapet, Mysore, quartzose gneiss 135' Pulau Bangka 43. Broadwater Creek in the Darling Downs part of Stanthorpe 90- MOUDt Francisco Unsettled boundary claim Manambato, Iabakoho, Ambasivasy, Amboangitalo, Papango, ASIA 3(9). IIiadur dlls'tric't, Mhilisore 136' Pulau Singkep . mineral field, Queensland 91. Split Rock, Pilgangoora, Cooglegong ' . t t ' . ' . 87 Agiliioomanga’ AmpaSImeloka BURMA _ 81, GSSjtflndislirircl: ,PiclrlioireBihar 137. Kepulaun Riau 44. V€€VfiZ21e Creek, Blatherarm Creek, EmmaVIIIe, New South 3:2), Eildlilynie MAURITANIA 1. Wan Hpa-lan . 82. Ban'gaikalan. in the Hazaribagh district, Bihar, gneiss £3 g:;i:::‘ Kallmantan 45_ Torrington, locality 11 miles northwest of Deepwater, Black 94. Tabba-Tabba 8 2. Taungthonlon and mouth of the Kyanchaung in the Tavoy 83. Sonland, RaJasthan ' 140‘ Pulau Berhala granite biotite gneiss biotite schist Swamp, Stannum, New South Wales 95- Locality 10 miles south 0f Wodgina, Friendly Creek LOCALlTY INDEX 23—93. See plate 2. district ' . . ' 84. Sohawal area, Madhya Pradesh, laterite 141. Kembajang M’ountainsy Kalimantan gneissic quartz diorite 46. The Gulf, Kulnura, Campbells Hill, Ravensfield, and Ruther- 96. Encnlymns AFRICA MOZAMBIQUE 3. Heinze Basm in the Tavoy district . _ 85. Idar . 142' Halilit River Kalimantan ’ ford, New South Wales; also accessory in sandstone 97. Locality 10 miles south of Sheep Rock 94 T 4. Shwe Du Chaung and Lamawpyin Chaung In the Mergm 86. Nander-leambad area, Andhra Pradesh ' ’ . 47. Warialda, New South Wales, bismuth carbonate vein 98. Lake Jasper, Donnelly River ALGERIA . ete - - - ~ - . 143. Motta Baoekonoe south of Babkanlem and south-southwest . . . . , , , district 87. Ranchl district, Bihar . 4 L l 1 l h f D bb N S h W l 99. Localit 10 miles s h f Ab d 95 Boa Es eranc art f Alt L h d t t f W kl b T b d W 8. oca ity 8 m1 es nort east 0 u o, ew out a es y out west 0 y 0s 1. 1 Tounin r te - . P a? 0. ,0 ,lgon a IS no 88. Purulia district Kataholdih Bihar ad'acent arts f W t 0 8 05°69 “wee“ a ea“ an oonarl, Mom Toe' ' ' 100 Sh n e, g am 96. Ribawe Mountains Bw1bw1 River Sawa River Maputa River CEYLON B l ’ l ' J p 0 es ’ batan near Toebatan sandstone 49' Locality 15 miles SOUth 0f Oberon, near Mount Werong, New ‘ aw CENTRAL AFRICAN REPUBLIC N ' R' ~ 1’ l ' ' I ’ , ' - ~ _ enga , , . ’ South Wales 101. Globe Hill _ , , , , rass‘. we“ a?" f “V131 “dune“ 5- Nmeua GangaI We Gangai Kara‘mta’ Wtralul’edOIaI Mara 89. Satbhaya, Cuttack district, Orlssa SARAWAK AND NORTH BORNEO 5o. Thackaringa, Broken Hill district, New South Wales, thorite- 102. Moolyella 2. Cheniandaka, a tributary of the Ngriss1 River; quartz-musco- 97~ Mozambique—Quelimane area pona, Ratnapura district, Erabudhdeniya, Halgolla Oya, JAPAN ' . d vidite veins‘ schist and neiss 103 Poona area Murchison oldfi 1d vite schist 98. Mouth of the Rovuma River Gampola, Ulupane, Lawpitiya Oya in Mapltagama, Pan- 144- Lingga, Gunong Lesong, Sarawak 51 T a. l T d'b Ii Av c gI‘he Ent c Ne S uthW les 104' Greenbushes g e 3. Jakundu 99. Vila Luiza akuru Oya in Deraniyagala 90. Taijin—zan, Shiga—ken, Honshfi 145- Sungei Entabai, Sarawak ' erriglat, u 1 ar ng, 0 a, ran e, W O a ' 105' Dee Riv r 4. Ippy NIGERIA 6. Bintenne, Hambantota, gneiss; also littoral sediments 91. Ishikawa, Suisho-yama, Ishikawa-yama, Fukushima-ken, 146- Batang Rajang delta near Sibn, Sarawak san S one 106' Vlanliimu; , , 7, W ' , ‘ H h" ‘ ' ' 147. Tan’on Batu t T ' K‘ d ,S k ' ' ; . ETHIOPIA 100' Oban Hills, Obong, Ukpong River, Ibum, Nsan, Calabar River, 8. K133393521 Eggs; gneiss . 92' NaegrilsVlilagsgcrfiitlltfezndl£11ugfi3l deposits 148. SungeigSegamastrifirl‘Sir-ngdl ong arawa South Australia . .. . 107. bwan River 5. Dacata River at Errer Iyanyita River, Uwet district, Netim, Okarara district, 9. Kaduwella, Ambalaiva, between Nugatenna and Madugoda 93. Nanzan-mura Saga-ken Kyushu 149- Sungei Tingkayu, North BOI‘HGO 52’ ngs Bluff gold mine'near Olary, auriierous quartz vem .108' Capel 6. Quoscerscer Akwa Ibame area, Kwa River, Uyana Ikpofia, Ebara River, gneiss granite pegmatite' Metihakka fluvial sediment V 94. Amagi Fukuoka-ken Kyi'ishi'i THAILAND 53' Mount Pitts—Mount Painter area, Fllnders Range, corundum- 109' Koombana Bay’ Bunbury FEDERATION OF RHODESIA AND NYASALAND Niaji, Enimayip, Ndebbiji, 1133i Creek, Ikpan River, Oban, 10. Kalkudah, gneiss); Mahaweli’Ganga, fluvial sediment . 95. Yd, Isliii, Yamaguchi1ken, Honshi'i mica SChISt; pegmatite; quartz-orthoclase porphyry NEW ZEALAND . . . Mango River, Obutong, Klmkhe Creek, Iboboto stream, 11 Ambanpitiya Aninkan'da Morawak Korle Muladuwanella 96 Hiei-zan Kyoto-ken HonShfi 150' Thung Kha 54' Mount Lofty Ranges N h . Changwena stream, Mumpu Mountain, Irumi Hills Calabar Province ' Durayakande Gilimale neiss e matite’ 97‘ Hase—machi Nara—ken Honshi'i 151. Phang-nga River in Changwat Phang-nga 55. Glenforth, cassiterite-quartz vein 110- g5} ere dredge, Atarau dredge, Blackball dI‘Edge. Grey ~ Nkumbwa . 101. Oyi stream, Abagana, Okpudu 12 Balangoda Deriai ama Estgate ,ep IEatite' Kelani Gan a ac- 98. Aichi-ken Honshii ’ TIBET 56. Yankalilla gorge southwest of Normanville, pegmatite; River d’redge, Red Jacks dredge, Slab Hut dredge, Mont- 9. Chasweta, Mwambuto Hills, Nachomba Hill, Kaluwe 102. Benin City, Eleru stream near Siluko Okwa Igolaw Abega ' -’ 1g ,p g - ’. . g ’ 99. K' — i K b - Y - - . l Myponga Hill, aCCBSSOI‘y in SChiSt gomerys Teriace sluicmg claim, Greymouth area, Grey 10. Dedza and Masamba, granulite and gneiss; sediments in stream Ikpoba River Ohuma River Ohi Hiver Oi‘oghodo (1151530141I ”Ocoanomerate) also fluv1alsed1ments, Amugoda, 100. Mukpb-ZTE Ugokel-ygma,h_amanashl—ken, Honshu 152. Brahmaputra River near Chaksam 57‘ Kangaroo Island River-Gillespies Beach region including Arahura dredge, Dwangwa River near Litala village, Kapyanga village, and stream at Agbor, and Nyama streani I pafigiO61yayéfitagrgfgggoggaagayaégzfigg‘igaglzfithxdi: - a a e, am 1. en' ons u AUSTRALIA AND NEW ZEALAND 58. Strathalbyn Kaniere dredge, Rimu dredge, Gillespies Beach dredge, Tambala Village _ 103. Wamba, Plateau Province; also accessory in pegmatite dikes sawella Hunugedeniya in Rratgama Walawey Ganga in KOREA Northern Territory Tasmania Westland and Nelson Diviswns, South Island 11. Kasupe and Zomba, gneiss 104. Egbe, Kabba PrOVince; also accessory in pegmatite dikes I . - - Y ' ' 101. Kw n ' ' l d' S "U — ' S "’ ." _ . . . - - 111‘ Port Pegasus dIStrICt including the Tm Range and Mudtown, . . Morahela, Sitawaka Ganga in Deraniyagala fluVIal sediment a g3u area, inc u ing ongJong n1, ongJong up, Kwangs 1 W If H 11 lf t t 59 Rln arooma RlVeI' St ‘0 I l (l 12. Lungu H111 and Monkey Bay, apllte 105. Mama area, Nassawara Province, Arum River, Marhai River, 13 Komari neiss Pin arawa fluvial sediment an—guii, Changp’yb’ng—mydn, myang—fip Tamyang—gun Chdl- ' 0 ram 1 ’ “(0 rami e-ouar Z vein 0' S g d l - - ewar S an . . 13. Balaka, Ndeka River, Ncheu Jinni River, Farin Rua River, Kwara Baba; also accessory 14' Batticaloi n iss ,Igld . ’ t’t . T' kk ‘l 1'tt l la-namdo ’ ’ 2. Nungado, stanniferous greisen 6 . cotts a e district . . . 112. Westport area including Barrytown Dredge, Charleston, 14. Kangakande Hill in pegmatite dikes . sediment: g e , e eniya, pegma l e, iru ov1 , i ora 102 Posdng-gun Changliing gun ChO’lla namdo Queensland and New South Wales 61. MolliaanIountlfClau‘de, Logirtlna arias, quartz veins With cas— Waimangaroa River, Whareatea River, Cape Foulwmd, Fox . . ' . y u :1 y ' V u U - v . t , ' t. ‘ ‘ ‘ - - - l2. $3113”; Islllalilrlid 106. Bauchi area, syenitc . - . . - 15' Nuwara Eliya, Buluhela Oya, Ambawela, Pattipola, Totapola, 103. Munbfiek-my‘on, Chnch’onU-gun, Ch’ungch’ong-pukto, So—un— 3. Johnstone River, Queensland 62. L:;efile:dwo rami e an ismu lmte 113:2;.{gig};feiggjryfitfigfiaglgr’ Otututu River, SOUth 17- Jack ltli: claims 107, Duchin Wei Hills, Rakwa B1ver,Chawai River, Zaria Province granulite, pegmatite, fluvial sediment myon, Ansong-gm, Kyovnggi-doi Ch'onJan area including 4. Batemans Bay, New South Wales 53_ Stanley River tin field ‘13. Patea, Tiaranaki coast North Island 18. Ebonite tantalum claims 108. Leger]; DIilitse Iglllsl; Llruein _Kanol Hills, .Banke' Hills, River 16. Kamburupituya, Naradeniya, Hikkaduwa, gneiss, pegmatite, Songhwan, Ipchang—ch’on}, Ansong-ch’on, Ipchang—myon, 5. Tweed Heads, Fingal Point, Cudgen Point, Cudgen, Nories 64, North Heemskirk and South Heemskirk tin fields 114. Paparoa Range, Nelson Division, South Island granite and 19- Kungus River 109 Kuravga Kegarfaeru, granite, a so luv1al sediments and conglomerate; Pamunugama, sandstone; Elpitiya, Bat- Chigsan area, Chiksan—.myon,USungnam, Siunhung, Paebang- Head, Hastings P01nt,'Potts Point, Mooball Beach, Crabbes 65, Mount Bischoff area; placers, but also accessory in granite and gneiss I 20‘ North and south branches of the Lisungwe River 110: Awuru ’ g uwangala, Galkandadeniya, HotadeniyanG'odamunna, Mas— 23:: SingiflEfciygllnfggggb Tong—myon, Ch onan-gun, 6 R'Cllieek glitch 1‘;ng BrhghtémWBeachi—INew South Wales quartz veins . . 115. Reefton area, Nelson Division, South Island N k k 1 N d R Ch. . mulla Kele, Patambe E13 I—Ilnldun‘laY Hlnlduma, Nelluwa U g I ‘U g g 7” Iv V - 1C mon Iver: vans ea l 00dy ead BeaChy MacaUlayS 66. Mount Stormont, Yellow Band Plains, Meredith Range 116. VlCtOI‘la Ran 8 Nelson Division South’ Island 21. yan 0 ca stream, yama zere iver, lkukula River, - - 104 Ch h - P kh - h H h P k g I I Nyangundi River Lifulund River Nswadzi River Nama- REPUBLIC OF CAMEROUN district, Pelawatta Ganga, Rakwana Ganga near Huduman ‘ swig owonu up, ,3 Va c on, an-c Von, ae usa—myon, Lead, Cement Lead, Jerusalem Creek, New SOUth Wales 67. Mount Stronach 117. Buller River, Mokihinui River, Bradshaw, Fadeown, Nelson lundo Hill near Chiromo, Tangadzi River , 111. Dikwa Division Kuda, Pusse Dola, Narunkandure Dola in Dobagammana, i;?:::'$§§:’gglldgn_up’ ICh on-gun, Wonsam-myon, Yong- 7‘ Nortlé Stradbroke Island, SOUth Stradbroke Island, Queens— 68- Mouth Of Frazer River, King Island in Bass Strait Division, South Island 22. Tributary ‘30 Ngena River near Tambanli Dwali River near ii: $630551 EggirafjdrléxTePIIiTZOTZleisildlijrlifnstedlmem; Negombo, Indu— 105. Kurye—giin, ChOlla-namdo; Hadong-lipy Hadong-gun, Kyo’ng— 8. Frzger Island Frazer Island Beach Queensland Victoria ills) éorelrebCollingwood district, Nelson Division, South Island Msen ~ ~ - i l a l ' ' 17 Kudremalai sandstone; also littoral sediment sang-namdo . 9- Thursday Island, Queensland 69- Mallacoota Inlet, East Gippsland . m e ove, Freestone H111, Lake Manapouri, South Island, 23. Mwanza River near Myowe Hill, Nankande River 114~ Yaounde RlVeT ' ’ ’ . . 106 S k ' K" V p ' H ‘ V K" - 70 c. E sandstone 24 N m Ri r i 115. Dschang Eseka River 18- Ranchagoda near Matara, Malwattai gneiss and granite; also ' ong P‘rl’ umsan-myJon, Congsi'n’ arI—myon,‘ umJe—gun, 10‘ Cannon Vale Beach, Queensland ' ape verard 120 Waiau Valley Round Hill Ourawera Stream Lon w d - Zgo a ve L' d . R' fluvial sediment fluVIal depos1ts; Chang-up, Cholla-pukto, granite 11. Mackay, Queensland 71- Pinch Swamp Creek, Bonang district 0f East Gippsland . distri t S thl d S thl l d , g 00 25' anseu stream, inga Z1, iver . . REPUBLIC OF GUINEA 107. Kumma—myon, Wanggung-myb’n,1ksan—gun, ChO’lla—pukto 12. Facin Island Queensland 72. Koeton area of East Gi sland . c ’ ou . an ’ ou S an . . 26 Make 3 Rlver Son we Rlver stream below M11 nd IS VIII 6 19'Ya1kumbura area V V - u g ’ . g. . pp 1121 Flordland dIStI‘ICt South Island neiss and SChl t ‘ 3., . ’ 'g ’ .0 e 'ag ‘ 116. See plate 2. 20. Colombo-Mannar area including Welaboda and the mouth of 108. Choksang-myon, MuJu—gun, Cholla-pukto 13. Bustard Head, Queensland 73. Mltta Mltta RIVBI‘ at Bethanga . . ’ ,g . s Luflra River, River Chungu, Changaroma Hill, Sere River, . 1 K” _ "_ " ”_ _ I W _ ' 122- BObS Cove, Crown Range, Lake Wakatlpu, northwestern . . 09. um gang, Puyo myon, Puyo gun, Nonsan gun, Ch ungch ong 14. Burnett Heads ueensland 74. South G1 sland C 0 S A the Gin Ganga : Q pp Mwes1a River, Mpata, north endof Lake Nyasa REPUBLI F ENEG L 21 Maha Oya Marawila 113me 15 Inskip Point Double Island Point Queensland 75 P011113 AddlS Torquay Otagov SOUth ISIand; sandStone 28 IZ{_aseyat River M H'll Ch .11 117418 See plate 2- 22: Kalu Ganga 110. Ungch’on-myiin, Ta'ech'oanyO'n, Ch’Ongna—myb’n, Poryo'n’g— 16. Noosa Head, Maroochydore, Queensland 76- Phillip Island, Kilcunda, Balnal‘l‘lngi Point Hayley ANTARCTICA . iwa s ream. near uoma I , near emenyonga Vi 'age, REPUBLIC OF SOUTH AFRICA 23. Kaikawala, mouth of the Bentota Ganga gun, So-myon, Pllyn-myOle', Soch on—gun, Hongbuk—myon, 17. Caloundra, Bribie Island, Queensland 77. Mornington Peninsula, Davey’s Bay 1. Locality near Mount Erebus Vungwa River near Mwenemguwe, head of Fullwa River . . . Hongsong—gun Ch ungch ong-namdo 18 Moreton Isl nd B h Q l d 78 S t K'ld R' k tt P ' 29 Kaswenta stream near Majimpula village Katise stream near 119 Steenkampskraal in Cape of Good HO e Province monaz’t — 24' Pulmoddai, KOkkllal lagoon 1 1 H k' . T’ ’ u U o o. o o. u ' a eac 3 ueens an , ‘ am 1 a, lo e S omt 2 Cape Adare ' Mapangania village Luviri River near Katemba village ' apatite—quartz vein 9 I 1 e CHINA 1 . Ell/1'2“, hlgndgfigémyloun, 'ICiliedolil‘gunCiijthull’ Chfionm—myon, 19. Southport at the Spit, Surfers Paradise at Wharf Road, 79. LaTrobe River 3. Gaussberg Michowo stream near Ngaloto Village, Nyika, Rumpi River: 120. Namaqualand 25 Ch‘ h h . H P _ 01: n’cmoni 03h? 0n. U 0-? 011, OCUIWEE; OH-gl-gun, Broadbeach, North Burleigh, North Nobby to South Nobby, 80. COImadai 4. Garnet Point and Cape Denison, accessory in kyanite-biotite Njowi village Nhuju stream Henga valley 121 Molteno sandstone 26. Chlang- hua hSI.en’ Kunan .rgvmc'e Ch’sif:gch¥§iig pcukatiig-myon’ uyong-myon, ongwon-gun, gurleiglh, dPalm Beach, Flat Rock Creek, Tugun Beach, 3;; it???“ gneiss and granite gneiss in moraines; Commonwealth Bay, I 7 - I . ung—s an Slen, wangs1 r0v1nce - ueens an . 1 accessory in pyroxene marble lNTERlORiGEOLOGlCAL SURVEY. WASHINGTON. D C ~19677665254 Base from U.S. Naval Oceanographic Office chart 51888, Boundaries are shown as Of January 1, 1962, and should not be regarded as having Official significance MAP SHOWING DISTRIBUTION OF MONAZITE IN ASIA, 500 500 . 1000 1500 l—-ll'-—ll—l O 500 1000 1500 MERCATOR PROJECTION SCALE 1:26 000 000 AT EQUATOR 2000 KILOMETERS 2000 MILES Compiled by William C. Overstreet, 1962 AUSTRALIA, NEW ZEALAND, ANTARCTICA, AND THE EASTERN PART OF AFRICA UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY PROFESSIONAL PAPER 550 PLATE2 75° 165° 150° 135° 120° 105° 9 75° 60° 45° 30" , 15° 0° 1576. V m " ‘ v . Kuhn Cl . p a . Ha slellerbugten B E A 0 Lowihery GnIIIIKE-PLJ 1m“ I KONG ' SkillePPendulum w ”"T ' U F O R T S E A OUND . a BARRO STRA/T Djaevelens Tummelfinger CHRISTIANX Wollaslon “"13"! G R E E N L A N D 0 Prince Alfred VISCOUNT MELVILLE S C.Berkele < B A F F I N oClavering 9 LAND Hold with ant‘ S E A n Marlin 'Kap Broer Ruys Russell P" u “ Siefansson 5 Iler B A Y . Q irsi i ‘31:: .19, . Q) i: - Eph: Fjord QC; Eclipse ham Moore ‘ 6.335331%“! I: Peninsula gamut 3C Bowen I 92 A Q) B ‘ .’ ' i\ R “1’71 . V _ ,o' g. Cape Kellett ‘ 5" ‘ 32% ‘ ‘ l Sc r b VI "sex/oi Sir. 3,, 0 68 y 2: Pt Barrow C-SCOTCSI’Y X; fl. ' Land rlsllerg Fjord Ei \“" - lie. 9 Karrats Fjord " ' .7. G R E E N L A N D Liver I Z Bay rnie - i 90” JamMayenfl Lg: Pt Franklin C- Lambm" C W C Umanak Land l .ett . . é: crgl‘on‘es Islands AMUNDSEN GULF b I 5 I ) . 0 a x) . I O ' I o : “‘ m , ‘ KONG K... ow... N 0 R W E G I A N 5' a w; Wollaston w R Q < L '7 _ I I3: MACKENZIE" a ' ‘ Peninsul‘n " Co iIlliiier‘nksv Och Q ! C.Rapcr I O'I‘urner ¢ :1 1}. ‘ i k, ' '~' 0 i 0 ”be”? 3” CHRISTIAN DEN IX 3, K “D 1, ml *‘ < Rowleyl 0 ~ {\ ,_,, ap a on l ' “ '7 g Bray I :I'; .l‘ Kap Ryder \\ Calie Lisburne jg ‘ , g g g Q C LAN D.“ KL: Langol’ 0 (III " . H V l" \7 Lu. QUEEN MAUD ' % Committc Z a , \/\ I—iPt Hope / e Islands u \233 ° . ‘51 - lha do Plco \ 235 @Ilha de Sic Miguel , 236 .. Ilha de Santa Maria Cabn de sao Vicente 323 O C E A N . Z ( Sant Barb a Is k, u a S :1]:- l v“ 257 263 Madeira Islands U; K “s ”g,“ 255 265 262 256 Bermuda 9 , V ll \ an em a \ / A T L A N T I C 273 l/‘ _,_, Tlhnn sol - 30 0 30° 4’ ’ CANARY is l Guadalupe q 315 185 7 \ 274 La Palm?) T crife ‘, 0 188 124149 A—300 GomeraoY? A L G E R I A ) L I B Y A Hierrd” Gran%a 18 G "3931299 298 294 “ rang: , 4 G U L FT8 1 -' Great A aco 282 Caho Bolad :‘/ Lay on I 13 s Escollns Alijos If , _ ~ .. ,. 1&9 didEleuthara BAHAMA \\\ r’ M E X I C 0 .‘s’o’rc‘n' ‘ News , d “\ s A H A R A \ wF’fl'ELF’v‘H‘flSiWL’i _Necl MM" 0 b flow DOMINICAN 5,6 ‘-'\.\ ,/ Kahoolawe \ s 9 \‘ ~ , d f REP. <2" MALI ’ Hawaii Islasde Revnllsgige o 2 HAITI 6} DA PASPAGE L" _/ NIGE R I l CI to 1518 Socorron \\ % VIC -: ANEGA /l S a a l n J ICA . ’_ ~. 7 I ,\ :# AMA Q PUERTOV‘i-rgin Is; I LEE ARD ~ CAPE VERDE; IS \ I <‘ . HONDURAS RICO - I b S Sanst:0 [ii/2:29:0- v. 0531 [I / ' I 165° 150° 135° 120° 105° 90° L 38 37 Guadelouperli' O C E A l V 3,; oBoa Vista _/ ' x 7" A --—-——-- —~/ - 15° W Dominica“ 0 largoke ,’ i‘f _ ‘1) ’ '/ 15° EXPLANATION UNITED STATES OF AMERICA Georgla (3‘ f» C A R I B B E A N S E A Sig/I itinique F°B° F SENEGAEl J /x 2'5 ' The symbols show the reported location and mode of occurrence of Alabama 141. Cluster of five symbols; . 't _ t't \A; rJV WINDWARD as: THZCTIt 5;;‘3 \\ ,~ “/x \ (\"\ ,’\ “—‘5”, monazite. The number opposite a symbol appears in the “Locality 40' Chilton County fluvial sediment; crystalline rocks (a) accessory in granlte, gnelss, gram e gnelss, pegma 1 6, fiICARAGU b 0mg” 9, Barbados GAMBIA ,D' ___117__. I LTK. . ~ ~_/ Chad . n . - u - - n e - ’ . - , . fluvlal sediment 1n the area of the northeastern X at , ru ax 1s 1 8 r J UPPER V0 A index - The numerical order m the Locality index follows th? pr 5 41. Rockford, Coosa County, fluVial sediment, granite . 11 , , H t C t D . . 'Ro .. .\ '0 rm- _ _,GUINE . ‘ , - entation in the text, except that closely adjoining.localstwswwhrch for 42. Tallapoosa County, fluvial sediment; granite ‘ ” W“ “ Bowersvflle, Hartwe 3 Roystoni ar ounlgfl‘ tel}? d‘ 56’ s F ‘30“; , ./ REPUBLIC i I /‘-.../— EEK ‘ ) geologic reasons may bediscussed separately in the text, are included 43 Chambers County granite gneiss Elbert COUHFY; Danielsv111e, Carltonil CO 91‘ , a 15011 COSTA RICA OF UINEA \V ”VI ‘. A}\ ‘ >4 ‘ ' ' ' . .‘e . ’ t . Lexmgton Sandy Creek, Falling Creek, Barrow ’ a ”A ,I\-' ‘ . , . ‘\ m - under one symbol on the map. The spelling of place names accords With 44. Phenlxv,Clty Coun y, _ I . . 107 5/4 ,‘ , $52 , , 9| 2 / usage 0f the U.S. Board on Geographic Names if decisions were avail- ' 1'5. 0005a River Prattville Creek, Oconee'Rlver, Oglethorpe County, . ‘ f1 _ l Slfl§3 116\ 47“ TV} if ‘ O” able. Place names for which no recommended spelling ’was available .: -' 46. Troy . ' (blaccessory in granite, schist, gnelss, migmatlte, uVla . 5 8750 ,, 5p V {mm} ,3; are given as they were in the original sources used for the text. Vi. ' . .. - _ ,1 _ sediment in the area of the central X at Athens, Barber V E N . , 155V, 4' Ci? 0-48 - a, ' . . ' ‘ '. ' ' . ‘ ‘ ' V ' (Alaska “j‘ . - - , Creek, Princeton, Bear Creek, Clarke County; Monroe, \__\ Eyi LIBERIA: 4.4/0 42 . ‘53 I '... 5,; .1 L. .- O P" i“ ' . v.1, ' ‘ ;“ ' 47. Mountiainlill'i’ew gold mine, Hyder district, molybdenite-gold- gValton EdouILty; $3321rigtggolgcehvgtoiiiiimigéoiiaccisookn \p__’) 1 ”\JVORY ““453 37 ‘ If“ All? : I ». . . _ 3'?“ ‘ ' ‘ quarti Véin 9““ y; ar urg: e ’ ’ ’ ‘Isla del Coco ,./ " Monazite occurrence in unconsglidatéa,andpoorlyu ,‘ 5., i 48. Salmon Bay, Prince of Wales Island, carbonate-hematite vein Middle Oconee Rfiver, Egrber Céeek’t Regal” Cé'eekl; $3.3? M/q 38\ 36 54 consolidated sedimentary rocks.“ °- 3‘ 49- Goddard Hot Springs, Baranof Island, granite Creek, MUIbeny wer’ arrow 0““ 3" ose ree ’ 1 ' Isla de Malpelo ‘ . . - -. v . .- '. cat Creek, Porters Creek, Butler Creek, Barber Creek, ) M ml beach and stream depostts of Recent- age mc‘ludes 50. Junegu ,. , . . / \ a y ' residual deposits , ‘ ,i 51. -Mou ’ ”spur-r arlea McNutt Creek, Middle Oconee R1ver, Oconee County; L {/J k , , if 52..Rou "' end Bar and Red Hill Bar Kahiltna River (c) accessory in granite in the area of the southwestern X 0 M B _A__J % Ilha do Maraca Q. GULF OF GUINEA V v-Vshal Bari Kahiltna River ’ at Stone Mountain: DeKalb County; L, I‘ _ Rochedos S50 Pedro e S50 Paulo X ‘ Peteilsville ’area ((1) fluvial sediment, granite, pegmatite, in the area of the 00 l,” (‘9 E Q U A T O R sao Tome/(7 . _ . ‘ .,Poorm‘an Cgreek lgwelr; Céhat CliernhontR'The 4Gla.clles,dHall Sountyf; Dnulgfis a , Cabo Pasado \ “\ Cap [Opel “ Mona'zite occurrence as an accessory mineral in con- 5 Cache'Cree’k—upper Peters Creek area, Yentna district rec l atta 000 cc WIT" m1 es 9W“ ream r0 e Isla San Cristobal . Annobén ‘ solidat'ed sedimentary metamorphic, and igneous .' Atwater Bar on the Mosquito Fork of the South Fork of the mouth of Duke,” Creek, W 1te County, . ' rocks 1 . . l5: . FortymilefRiver (e) fluv1al sediment in the area of the upper O in Rabun L \Aas Boas Includes fossil pldders; exclusive of occur'rénces in bodies of __ , Copfief Creek County; Golf» dc Guayaquil b\°\ h pegmatite,vei1is,ilnd carbonatite masses , _ Coal Greek and Woodchopper Creek 142. Cluster of four symbolszi ' . . Fernan lo de Noron a ‘ . SlatezCre‘ek, granite; fluvial sediment (a) accessory in granite, granite gnelss, gneiss, terrace “ . Ober Creek near Donnelly gravel, fluv1al sediment in the area of the western X at . _ Nome Creek, Chatanika area La Grange, West Point, Yellowjacket Creek, Flat Creek; . , , , Ruth Creek, Liven ood area Beach Creek, Flat Shoals Creek, TroupCounty; House Creek, JMOnathe occurrencein pegmatite _ Excelsior Creek, Migsion Creek, American Creek, Eagle-Nation Mountain Creek, Palmetto Creek, Pine Mountain, Harris .Ascension I ' Commonly ”’8 mm” accessory mmem area, granite, Tertiary gravel; fluvial sediment (Cbo)unty , 't _ fl , 1 dim t in the area . 65. Bedrock Creek, Miller House, granite accessory 1n gram e, gnelss, “V13 se en 66. Portage Creek, granite; fluvial sediment of-the eastern X at Zetella, Heads Creek, Shoal Creek, .4 A 67. Rye Creek, Wiseman area Wildcat Creek, Flat Creek, Flint River, Spéildln‘g‘} Coilinty; . . . 68. B’ ’C k,T b' C k,L'ttl S C - GreenVllle, Harrls, Durand, Warm Springs, ay, 00 ury, ., Monaz1te occurrence m vein igolgegenci (I): cheSouth 1:0Iiufiythzefiiéfifuiqiéawwesreek, Sulfur Creek, Meriwether County; Sharpsburg, Coweta 69. Elephant Mountain, Eureka; quartz monzonite, fluvial sedi- (éoun‘zy; Honey Bee Creek, Berh Creek, Elkins Creek, Plke ment ' oun y; A ' - matite ranite in the area of the southeastern peg- _. 70. Deep Creek, Sullivan Creek, Tofty, Manley Hot Springs- (c) peg ,g . o I . ° Monazite occurrence in carbonatite Rampart district inaéite symrgoégltnltfbateswlle, Thomaston, Upson County, and 15 Lagé mm“ s H 1 ANGOLA 15 . . . 71. Hot Springs .Dome, Roughtop Mountain, Boulder Creek, in raw 0 ’ . . . § 0 t. eenaI Manley Hut Springs~Rampart district, granite; Tertiary (d) northwestern pegmatite symbol in area of Franklin and . '. f . gravel Texas, Heard County 93 ,' 10 A v . ’ . . ' - k McDuffie (' 4 Calm Frio ._ ' 72' Nixon Fork district 143. Augusta, Richmond County, Sweetwater Cree ., (I I MonaZIte locality 73_ Julian Creek, a tributary of Middle Fork of the George River County; Warren County; Glascock County, Jefferson \ B 12aA L \ M0116 ofoccm‘rmce unreported 74. Candle Creek, a tributary of Tatalina River, McGrath County; Way nesboro, Burke County . . . 1 1’\l ' 75_ Golovnin Bay between Cape Darby and Portage Creek Seward 144. Sandersv111e, Washington County; MllledgeVllle, Baldwin Ilha d3 Trindade . Peninsula ’ County; Jones County; Wilkinson County; Dry Branch, Bibb ~ . Palgmve Pom, _._..-__-._.._..-_. 76. EarM t‘ - ’ 't County Twiggs County _ _ _ , ' , d . 77:Bi‘ookS’lM-loililiiltagiiliagiie: granite 145. Macon, Bibb County; Peach County; area between Knoxv1lle, \> International boun {try 78. Cape Mountain area, Cape Creek, Boulder Creek; also acces— Crawford County, and Butler, Taylor County iiiiiiiiiiii _ 7 1- A *1; B “70* P7 A, MC“ i v “07 F __ _ _ Q ,,_ i I ng A BC" 9 ,R, fl iiiiiii a A ‘ ‘ ¥ 7‘ i K L, H ‘ 7 i . sory,.in'granite- 146. Parts of Talbot, Marion, Chattahoochee, and Muscogee ’ i 1 v i i i ‘ i i * i y "i 1 i iiiii 21 L ................. Arizona _ " ’ ’ ' Counties east of Columbus; Chattahoochee River at 79. Black Canyon Creek, Yavapai County Columbus, MUSCOEGe County Unsettled boundary claim 80. Chemehuevis district, Mohave County 147. Coleman, headwaters of Cemochechobee .Creck, Randolph Isla San Félix 30,, 15., Go 150 81. AquariusMountains, Mohave County County; Chattahoochee River at Fort Gaines, Clay County "Isla San Ambrosio LOCALITY -INDEX Arkansas: - ‘ , i 148‘ Liberty County; Bryan County; Tybee, Savannah Beach, 242, Defiance, Standing Rock, McKinley County, fossil placer 272. Rocky Mount, Tar River, Edgecombe County; Black Creek, ' AFRICA 4“ ‘. - Skldaway Igland; Ossabaw ISIand’ Bryan CW“? 243. Gobernador, Stinking Lake, Chama River, Rio Arriba County, Wilson, Toisnot Swamp Creek, Contentnea Creek, Wilson GHANA it i '82. Magnet Cove, HOt Spring County ' 149‘ McIntosh County; eastern part Of Long County, Altamaha fossil placers, fluvial sediment County; Pine Level, Johnston County; Rose, Nahunta Swamp ' ‘83. Mineral Springs, Howard County, £08511 placer R1ver, Long County; Sapelo Island, McIntosh County; St' 244. Star Lake, Miguel Creek dome, McKinley County; Hovey Creek near Patetown, Neuse River, Goldsboro, Wayne 36.,Accra_._ ‘ i- V i ‘ 84. J-onesboro, Cralgliead County Catherines Island, Liberty County 30° Ranch, Sandoval County, fossil placer County 37-; Bi wand Volta River W; , , . . _ . . 85. BlytheVllle, Mississmpl County 150. Southern part of Glynn County; northern part Of Camden 245. Herrara Ranch, Sandoval County, fossil placer; Rio Grande 273. Cameron, Aberdeen, Moore County; Timberlake, Raeford, Pine 38' Cape Coast and Salt-pond, quartz vein in pegmatlte, fluVlal 86' Helena, Phllhps County County; Nahunta area, Brantley County; Racepond area, at Bosque, Valencia County, fluvial sediment Bluff, Lumber River, Hoke County; Hoffman, Hamlet, sediment . ‘ - :, California. Folkston area, Charlton County; Jerusalem area, (gharltori 246. Shandon, Pittsburg district, Sierra County; Rio Grande at Richmond County; Silver Hill, Old Hundred, Laurinburg, 39' Western,Ak1m and Winneba ' M ' P ‘ B d' and Camden Counties; St' Simon Island, Long Islan ,Jekyl San Marcial, Socorro County Scotland County; Lilesville, Pee Dee River, Anson County 40' Tark‘wa,‘ fluVIal sediment; Daboase, granite 87. ountaln ass, San ernar lno County ' Island, Glynn County 274. Purvis Robeson County' Lumber River near Boardman 41. AshantiAkim, KumaSii.ana Obuasi 88' RickbCorgtl areallBlaik 1120i clamal Pongna T111654 quarry, 151. Locality 3 miles west of St. George, Charlton County Islas JuAan Fernandez New York Coluinbus County ' ' 1‘48ng i ' .’ ”' '- '- m oy, ucca Va ey, uc y even aim, opper ountaln, 152. Oconee River, Altamaha River, Wheeler County; 00111111899 247. Adirondack Mountains, St. Lawrence County, magnetite-rich 275_ Weldon, Northampton County; Roanoke River, Halifax County - San Bernardlno County, Twentynlne Palms, Live Oak Tank, . . , . . . _ . R' ‘d C ’t _ P' t B . S B d' R1ver,Telfa1r County, Altamaha R1ver, Toombs County, granite gneiss 276. Winton, Hertford County, Cashle River, Bertie County; ‘ ' ,, ' ‘ lvers1 e ounty, granl il’ in 0 as1n, an ernar lno Altamaha River, Tattnall County 248. Mineville, Essex County, magnetite-rich gneiss Roanoke River Bertie Count and Martin Count ' fluvial sediment; Tain River, biotite granite I County,.quartz-blotlte s-ChISt . 153 Chattahoochee River Seminole County 249. Carmel, Putnam County, Yorktown Heights, Croton Lake, 277 C F ' B ' - k C t y y 46: Kus‘asinquértz "‘, ‘ ' . 89' 8°10 .diStflcli’ San Bernardlno County . d W‘l . i , Westchester County, gneiss, sillimanite gneiss, sillimanite- Oregon ape ear, runsw1c oun y 47- E3399?“ Ganja, fluvial sediment; Chimera° gramte 90‘ Mount 31170130“in BOXPSpfglgs Mounts‘glsl XaltVer 9' Jl ham' Idaho mica schist; Bear Mountain, Rockland County, gneiss; upper . _ 11 W 48' Kete K-raChi . I f son mm?’ out em' a-CI lc quarry, meies er area’ urupa 154. BoiseBaSinincluding deposits at MooreCreek, Granite Creek, part of Manhattan Island, New York City, New York 278. Weston, Umatllla County, Wa owa, allowa County 49' Dagom‘b‘a“ ' i i‘ ' Mountains, pegmatlte, accessory 1n granite Idaho Cit Centerville Grimes Creek Wolf Creek Placer- County, gneiss, schist, pegmatite 279‘ Durkee, Baker County 50. Asamang, muscovite granite; near Foso in the Nsuisen Su, 91. Cactus City, Riverside County, granite H' ' M . ville, Elk yCyreek, Fall Creek, Canyon Creek, Rabbit Creek, 250. Tully, Onondaga County, limestone 280. Antone, Wheeler County - Sirekuma Sittiotit’e schist and biotite granite; fluv1alsedi- 92- Descanso J unction, Ramona, Mesa Grande, mart .ountam Lakow Flats Summit Flats and Porter Creek Boise County, 251. Canandaigua Lake, Ontario County, limestone 281. Hood River, Wasco County ment -, (ii-.3 ,, __ at Pala, San Diego County; accessory in granodiorlte at granite fluuial sediment-pegmatite at locality between 252. Lewis County 282. Latourell Falls, Portland, Fulton, Multnomah County 51' Chichiweri, Abofuo, and Saru 93 B.D}esca?so Jgnctlgn t ‘t Garden'Valley and Grimes Pass, Boise County; Johnson 253, Long Beach, Nassau County 283- Failspltnyiigllé County . L’ 1 C 52. Nakwaby ‘ , . IS 0p, nyo 01111 y, quar. Z 11101120111 6 - - - Creek Gem County fluvial sediment' Garden Valley, Banks, 254 West Hampton, Amagansett, Suffolk County 284 MOITISOII,’ reekl Yaqulna Bayl 11100 n Ounty 3’ 0 ' B h Su Kade 94. Monterey area, accessory in granite; Marina Beach, Pacific ’ ’ . .’ . . Galfo de los Coro . 285. Foster, Linn County 5):. 1121213506 upongo, senasai, ers ea , Grove littoral sediments North Fork 0f the Fayette R1ver, B01se County, fluv1al sedi- North Carolina 286 South Fork Coquille River Coos County‘ Port Orford Gold ~ - 0 1a e ’ - - ment; Boise, Dry Creek, Ada County, fluvial sediment; . . ' ’ ’ ’ MAURITANIA 96. C(gitllliirndildtrliiltlsl’rrldeI‘gilegdlliliitly sandStone Dismal Swamp, Alexander Flats 0.11 the Middle Fork 0f the 1313 de Ch 0 255. GlgleanTIZCOleeeirOSgiiTiildllir, Rjdtllizifsorfijllti‘iik’ 5616198316316; 287 Wld’lefaCi'leimGFaiit): IP13 Kerb'y Sucker Creek Coyote Creek 88- Saint-Louis 97- San Joaquin'River near Friant, Fresno County OBoise fitivgr, Eémof g0Egigbi:::fialosv:d:§:%tounty I Mountain Creek, McKinney Creek, Rutherford County, ' Josephine County; Gold Hill, Birdseye Creek, Jackson 89. Port-Etienne 98. Merced‘ River, Merced County, Tuolumne River near La T56 81:32:31,113 ‘g‘OSEty “”3 , a 1 , y ARCHIPIELAGO fluvial sediment, schist, granite; Sandy Plains, Wheat County 90- Sbar ~ ' Grange Stanislaus River, Stanislaus County ' . . - 45° DE L05 45° Creek, Machine Creek, Whiteoak Creek, Mill Creek, Greens 288. Astoria, Hammond, Fort Stevens, Clatsop Spit, Clatsop, 91. Nouakghott ‘ i, 99. Indjfnnpccgolarvglegé (SgggpyRanch 14 miles north of Angels .. .- 157‘ CIE%$¥%;?rh§gzfirbgfiiiyLeWISton’ Snake River, Nez Perce CHONOS Creek, Groomer”, Polk County, fluvial sediment Clatsop Beach, Warrenton, Glearhart, Gearhart Beach, Gear- a... nun: ‘ ,_ _ . ' R' Ad C , . Golfo San Jorge 256. Todds Branch, Newell, Mecklenburg County hart Park, Seas1de, Carnahan Station, Clatsop County 93 E1 Memrhar 100. PlacerVIIIe and Indian Dlggings El Dorado County Sacra- 158- Snake 1V9!" ams ounty Peninsula Taltao . . . . ~ ~ ' NEA mento County Michigan Bluffiand Loomis PlaceryCounty 159. Bannock County '4 257. Brindletown, Silver Creek, White Bank gold mine, Hall Creek, 289- Randolph dIStl‘lCt, COOS County REPUBLIC OF GUI 101_ Rough and Ready, Nevada County, Marysville and the Browns- 160. Between North Fork and Shoup in the Mineral Hill district, Golfo de Pei. Calm Tres Pumas Pilot Mountain, Brindle Creek, Glen .Alpine, Clear Creek, Pennsylvania 116, Beyla ville district, Yuba County Salmon River, Lemhi Pass diStl‘iCt in the Beaverhead I l C Sutterwhlte Creek, Double Branch, Bailey Fork, Morganton, 290. Morgan, Boothwyn, Crum Creek south of Swarthmore, Gulley REPUBLIC OF SENEGAL 102. Little Rock Creek, Butte County Range, between Salmon and Tendoy on the Lemhi River, 33 amp“ Burke County, fluVlal sediment, quartz monzonltlre, figma' Run, Darby Creek in Clifton Heights, Delaware County; 103. Nelso P ' Pl Diamond Creek area, Leesburg Bas1n including Arnett tlte’ Dysortv1lle, Long Branch, Alexander Branc ’ acLe- P ’1 i P ila 1 hi unt schist neiss e matite 117 Saraya n Olnt‘ “mas county - - th B h D M dd C k s th M dd hl adelph 3" h de p a C" y’ ° g ' p g 118. Casamance River 104. Crescent City, Gilbert Creek, Del Norte County Creek, Wards GlliChi and M0059 creeky Smith GUICh, Naplas Isla Wellington. gra k NrarlllclVI dgmémni’ Glu y d r881 ’b Bou h (:11 fly 291. Masseyburg, Huntingdon County, sandstone ' 105. Trinidad Humboldt County Creek, GlbbonSVllle, Lemhl County, Idaho, and Beaverhead ree , ort . u y ree , enwoo , ae ranc , a e L NE - ’ - - ' _ ‘ ‘ _ GTrinidad Creek, Shadrlck Creek, Southeast Muddy Creek, Gum Rhode Island SIERRA E0 106. Prlnceton Beach, mouth of Tunltas R1ver, San Mateo County, Montana, thorlte quartz veins, pegmatlte, carbon i I M d d D‘ i i ' 153. Bumbuna, Sula Mountains, also accessory in granite 107, Pigeon Point Lighthouse, Point Ano Nuevo, San Mateo County, atite fluvial sediments s a a re 6 ms Bahia Grande Branch, Camp Branch, Nebo, Katy Creek, Magazme Branch 292. Westerly, Bradford,'Narragansett Pier, Washington County, ' K b i Ka-malu A N c eek P ' ‘ c 161. Cascade-Long Valley district including Big Creek, Beaver . , FALKLAND ‘5 McDowell County, fluVIal sediment, granite, gnelss, First granite, granodiorite; Block Island, Newport County, beach 154. Salonya, ama a , no uevo r , aJaro R1ver, Santa ruz County . . W. Falkland a.» . , , . 155. Manowa, Kailahun, Pendembu, granite Colorado Creek, East Fork Creek, Scott Valley, Horsethlef Creek, Isla Diego de Almagro EOE Broad River, Carson Mountain, Richland Mountain, South and ocean floor sediment 156. Mano River in the Kenema District Pearsol Creek, Corral Creek, Clear Creek; Bear Valley 3" m "Falkland Mountalnsi Rutherford County, fluyial sediment . South Carolina 157. Gbangbatok and Gbangbaia in the Gbangbama District, Jong 108- Copper King Mine» Larimer County Creek, White Hawk Basin, Deadwood River, Elk Creek, “GEM” 37“” 258' Mllhouands M1" 0“ T-hlrd creel" Hlddémte’ s-tony -P°mt’ 293 01 t f th b l t d' f th t t th River between Matru and Wobange 109. Park Range, pegmatite; Hahns Peak, Timber Lake, Routt Middle Fork of the Salmon River, Bear Valley Creek in- Isla Desolacid TIERRA Alexander County, vein, pegmatlte, gnelss,'fluv1a.l sediment; - 2:5? 0 ree sym 0 5 ex en mg rom 50“ W95 0 nor ' 158. Pampana River between Mamaya and Mamansu County, flUVlal sediment eluding Big Meadows, Valley County, fluvial sediment; northwestern part of Iredell County, fluVlaI sediment; Cub 1:“1 , 1 d‘ d _ 11. k _ 110- Jamestown area, Boulder County granite southwest of Peace Valley, Valley County; Lardo, Isla 5,3 I 95 . é Shag Rocks South Georgia Creek, Wilkesboro, Wilkes County, fluVlal sediment, gneiss (a) uv1a $8 lment an accessory 1n crysta lne roc s in NORTH AMERICA 111- Jasper Cuts, Fourmile GUiCh northeast of Black Hawk, Illinois McCall, North Fork of the Fayette River, Donnelly, West - ' 259. Spruce Pine district including Spruce Pine, Burnsville, North 39 “(:13 OfC tfek Sfiygléweiter: Scat ffikdergdvellilofilg CUBA Gulch south-southwest of Central City, Gilpin County, Mountain, Gold Fork, Stolle Meadows, South Fork of the ", Wlsla delosEs.ados Toe River, Crabtree Creek, Mitchell County, Yancey County, 9.3“” am 1” ‘i , 1 e“ ”5 e we , n n! .n‘ 1. Finca Parnaso, Victoria de las Tunas, Oriente Province gneiss, biotite-muscovite granite, fluvial sediment; Soda Salmon River, Peace Valley, Middle Fork of the Fayette I la Londonderry . 09 ' C. Disappointment 'and Avery County gigs}: hv/fdetCFr ErBighlghdeizgi CHESiTFI‘OIikeCrIZIdke 2. Finca Magdalena, Caney, Oriente Province Creek-Beaver Brook area, Clear Creek district, Clear Creek River, Valley County; Meadows, Adams County, fluvial °‘ .. QBahm Nassau 260. Zirconia, Henderson County . . W , C” k s eeh’R. B d a' Creek West R ck 3. Ciego de Avila, Camaguey Province County, pegmatite; Centennial Cone, Sweitzer Gulch-Twin sediment 151“ H°5te 59*: 261. Mars Hill, Hot Springs, Madison County, pegmatlte, sand- C eem ree ’ avllmnaC “1291313 roaRw i C 1; C b 0 d DOMINION OF CANADA Forks area, Jefferson County, pegmatite; South Platte area, 162_ Pend Oreille district, Hall Mountain near Porthill, Boundary Islas Diego Ramirez CA?§A1:E fi%1:§?s L stone; Fines Creek, Haywood County, gneiss (3:23: $223311; ofiakzeTea Click OIVeal rCei'eck “1:323; Newlands Gulch, Platte Canyon, Douglas County, pegma- County a o ,, 262. Shelby, Hickory Creek, Poplar Springs Church, Dover Mill, l , l l , British Columbia tite and fluvial sediment 163. North Fork of the Clearwater River, Elk Creek, Dent, Mus- 75 6O 45 Little Hickory Creek, Brushy Creek, Beaverdam Creek, greek, ChQEOke: grdfilli’ Iéen 1:30?) CreeRk, Bea: dCreek, 4, North Thompson River 112. Guffey-Micanite area, Park County and Fremont County, selshell Creek, area 10 miles from Weippe, Orofino, Clear- . N b k Washburn, Little Creek, Carpenter Knob, Toluca, Belwood, Covefn-OH Ti? ,0 a k e]; 1:6:6 911193331 niiii‘k 381135;); 5, Hazelton, molybdenite vein pegmatite; Boomer Mine, Park County, beryl-quartz-fluorite water County, granite, schist, fluvial sediment; Elk River, Malne e ras a Fallston, Lawndale, Ramseur School, Flat Rock School, LifldleyH osglfilinCrlezk l ABBeEi’sonreCoilntueand Abbeville 6. Quesnel River about 8 miles upstream from the Fraser River vein; Calumet Iron Mine, Chaffee County, Vugs in contact Orofino Creek, Pierce district including Cow Creek and 189. Topsham, Standpipe Hill, Sagadahoc County; Auburn, Andro- 220. Milford, Seward County Pleasant Hill Church, Double Shoals, Cadlsh Church, Klstler C t . (13% B d I C k Littl Bgav rdam Creek 7. Bugaboo Creek aureole around diorite; Trout Creek Pass area, Chaffee Rhodes Creek, Clearwater County; Eldorado Creek, Idaho scoggin County Union Chui‘Chi. Brushy CIIGEk, Z1011 Church, Bmllng Springs, Tiiunld,’ RligvereaCllilverriid rCFeek Aridersone Count and Manitoba County, pegmatite; Buena Vista, Chaffee County, fluvial County, fluvial sediment 190. Blue Hill, Hancock County, gneiss Nevada First Broad River, Polkv1lle, Buffalo Creek, Grover, Kings chrileeOCount _v Tugaloo River below Chauga River (Tconee . ‘ _ sediment 164. Elk City, Buffalo Gulch, Idaho County, biotite gneiss, fluvial Maryland 221. Mesquite, Clark County, granite augen gneiss Mountain, Casar, quartz monzonite, gneiss, Knob Creek, Count . y, . 8. Huron Claim, Wlnnepeg River 113. Climax Mine, Lake County, granite sediment; Baker Gulch, Crooked River, South Fork of the , 222- Clark Mountain, Clark County, granite gneiss B91) Branch, Maple Creek, Wards Creek, 'Blg Knob Creek, (b) fly" 1 sediment and accessor in cr stalline rocks in 9. Bird River area 114. Quartz Creek area, Gunnison County Clearwater River, Crooked Creek at Dixie, Penmans Fork 191- Northern Maryland, SChISt 223. Crescent Peak, Clark County, granite gneiss thtle K1101) Creek, Clooked Run Creek, Stoney Run Creek, h uVla f h th t y t G Sfif L'ttl ' h 11 Vill ' ' ‘ 192 Southern Maryland Grass Branch Poundin mill Creek Ma ness Creek Bi t e area 0 t e nor eas em 0 a ,a ney, 1 630 n Newfoundland 5- a Grove area, Crestone, Saguache 0011th of Big Creek, Lake Creek, Idaho County, fluVlal sediment , 224. Gold Butte, Clark County y ,' g , g i g C k A h th C k Ch k C k Littl Ch roke 10 N , L b d 116. Grand Mesa, Mesa County, sandstone 165. Warren district, Resort, Canyon Placer, Warren Meadows, 193‘ Ocean Clty’ Worcester County 225. Carson City, Ormsby County Harris Creek, Little Harris Creek, Bald Knob Creek, Cleve- Creek, BS word rge ’ k 3m 8W lr‘IiielI Cree: Beuffal: ' am, a ra or 117. Mesa Verde, Montezuma County, sandstone Idaho County, granite, fluvial sediment; Big Creek Ranger Massachusetts h' land County, quartz monzonite, gnelss, pegmatlte, blotlte ree , eaver. am ree ’ 0e e c ’ . . . . . . , , New Hamps II“? and Vermont - -11- - h' H - l - . Creek Broad River, Camp Creek, Ross Creek, Sarratt Creek, Northwest Territories 118. San Lina Valley, San Luis Valley, Costllla County Station and in Big Creek quadrangle, Valley County, 194 South Orange Franklin County , , schist, s1 lmanite sc 1st, uv1a sediment, Stubbs, Long G l P d C B ttl und Monument Cudds 11 M L B St k Lake dolomite C n t‘ t granodiorite; Grouse Creek, Florence district, Marshall Lake ' ’ - - 226' Randolph, COOS County, N' H.,.gnelss; Moosflauke quadrangle, Creek, Glen Creek, thtle Buffalo Creek, SHCk Creek, Muddy rassy . 0n ’ .owpens a egro ' . ' c can ay, ar ’ 0n ec lcu ° - - ~ - ~ 195' Westford, Ayer, Middlesex County, gneiss G ft C t N H - Creek B111 Martin Creek Horse Creek Suck Creek Thicketty 12 Y b Lake mi matite' lacustrine sediment . . . . district, Syringa 1n the Camp Howard district, Secesh 9 H d D dh N f 1k C ’3 _°n 0““ y, - vgnelss . Fork, Cleveland County, Lincoln County, Gaston County, , . . ’ . ' ° . - 9m 3 , g , 119. Yantlc Falls, in.Norw1ch New London County, pegmatlte, Creek Kelly Meadows Three Mile Creek and Ruby Creek 1 6~ M1 01‘ , e am, 01' 0 ounty 227. Wakefield, Carroll County, N. H., gneiss fluvial sediment; Crowders Mountain, Cherryville, Gaston Creek, Thicketty, Little Thicketty Creek, Macedonia Creek, Nova Scotla Sillimanite schist; Willimantic, Windham, Oneco, Windham near Burgdorf Idaho, County' Squaw Meadows Valley Michigan 228. swanzey, Keene, Cheshire county, N. H., oligoclase gneiss; County, fluvial sediment, quartz monzonite; South Fork Island Creek, Pacolet R1ver, Cherokee County; Chesnee, 13. Reeves farm and Lake Ramsay, in the New Ross area, Lunen- County, unknown County‘ locality northwest of’Meadows Adams ,County 197 Palmer area Gwinn Marquette County fossil placer accesv Lovewell Mountain area, Sullivan County, N. H., sillimanite Catawba River, Indian Creek, Howards Creek, Pott Creek, DOUble Branch, M3570, Spartanburg, Cowpens, Greer, Con- burg County, also accessory in granite 120. Watertown, Litchfield, Litchfield County, granite, unknown; fluvial sediment ’ ’ ' sory in quartzite and arkose ’ ’ schist; Bellows Falls quadrangle, Cheshire County and Lincolnton, Lincoln County, fluvial sediment verse, Becks Branch, Buck Creek, Casey Creek, Cherokee 14. Port Mouton, Queens County, granite 121 ChPotnpeT/I'Iifilateay NdéV‘; HiV9n lodgntityhsaggs'tirle d 166. Salmon River, Nez Perce County Minnesota Sullivan‘County, N- H., including BGHOWS F3115, Windham 263. Jacob Fork, Pleasant Grove, Ramsey, South Mountains, Camp 1031.636? POS'ERldfeAcgegk’ 1:53:63”; C:::;,l£):all‘il:1kdal(}ndli(3glrlffl1;’ 15 Albany Cross, granite ' es er, 1 e own 1S “c ,1nc u mg e rlc an quarry, 167. P tt R’ P tt C t ounty, t., gneiss Creek, Hickory, Henry Fork, Queens Creek, Laurel Creek, 3” ores ree l ,r a 13" r , , , , 16. Shelburne, granite Pelton quarry, and Hale quarry at Portland, and Haddam 168 Maxie FleatstjTinoirzeCoeilngm y 198. Pierz, locality 7 miles west of Little Falls, Morrison County, 229. Sunapee quadrangle, Sullivan County and Merrimack County, Enola, Dafty Creek, Ben Creek, Rock Creek, Cub Creek, BUffaiO Creek, RGIdVIIle, SOUth Tyger RlVel‘, Chickenfoot - ”1 Middlesex County and Glastonbury in Hartford County, ' ' uartz monzonite N. H., gneiss; Cardigan quadrangle, Grafton County and L 1 Cr k Cat b c unt nd B rke Count ranite Creek, Bens Creek, Allen Creek, North Tyger R1V9TiM1ddie Ontario pegmatite Branford New Haven County unknown‘ Lyme 169' Valley Creek, Meadow Creek, Stanley Creek, Kelly Creek, 199 Miimeiska Wabasha County sandstone Merrimack County N H granite and pegmatite ye (file ’ial 33",: i: Hy at; (131,er Do giechek’ Tyger River Jordan Creek Duncan Beaverdam Creek . . . . . . . . l l , r , ~ - - - . , , , - '7 gnelss, uv se 1 en ; un ng , u , , ’ ’ ’ 17, Dickens Township, Nlplssmg Dlstrlct New London County, unknown; South Lyme, Waterford, gjgttiecgiiiilfyGOId Creek, Williams Creek, Pigtall Creek, Mississippi 230- Ascutney Mountain, Windsor County, Vt, nordmarkite McGalliard Creek, Drowning Creek, Hoyle Creek, Island 3970ka SWi/Fllli) Caeek, Sgenclerbgreflk,PMapllet (geek, (51.63%; 18. Vermilion Lake and Kenora area Flatrock quarry, New London County, egmatite . - - . / ac son 1 s, rays ree , or aco e lver, ou 19 L ndoch Township Renfrew County p 170- Camp Creek, Camas County and Blaine County; Rock Creek, 200. Localities 10 miles east and 0.5 mile south of Oxford, Lafayette New Jersey 01961“ Burke County, fluVlal sediment, South Fork Catawba Pacolet River, ()de Creek, Bird Creek, Wood Branch, Law- ' y ’ . 1 d C k D d Sh c k B1 ‘ - . River, Clark Creek, Newton, Lincolnton, Catawba County 20- Parry Sound, Conger Township Delaware Poverty F ats, Ree. ree , ca 6613 ree , alne County 231. Dover, Chester, Tanners Brook, Morris County, magnetite- and Lincoln Count fluvial sediment' southeastern art of son Fork Creek, Meadow Creek, Green Creek, Shoally Creek, 21. Pitt Township 122. Atlantic coast, fossil placers County; Shoshone,.Lln001n County 201° Grenada, Grenada County; DUCk Hill, Winona, locality 23 miles apatite vein, gneiss; Oxford Furnace, Warren County, peg- Caldwell County fluvial sediment gheiss D Spartanburg County; 22. Blind River region, metaconglomerate Florida 171. Snake River near Mlnldoka, Minidoka County north of Kosciusko, Poplar Creek, Montgomery County .matlte 264 Cla County fluvial sediment‘ Masons Branch Caler Fork (c) fluvial sediment and accessory in crystalline rocks in 23. Don valley Toronto Lake Ontario, Scarborough Heights 172. Snake River, Blngham County 202. Marion, Lauderdale County; Newton, Newton County; Enter- 232. RlngWOOd, West Milford, Passaic County, pegmatite, granite ' y ’ ’ - - ’ the area 0f the central 0 at Moonville, Conestee, Five Mile b. , i 123. Mineral City, St. Johns County; Jacksonville area, Mayport, prise, Stonewall, Clarke County gneiss ‘ 3f Cowee hCrteek, MEESOES Mtiuntialn, Ig-lgChlalT‘dS, Mlacon Creek, Gilder Creek, Roper Mountain, Mauldin, Maple Creek, Que ec V 11 M M . V'II T h' 1 W t mouth of St. Johns River, Manhattan Beach, Jacksonville Illinois 203. Zama, Attala County; localities in Winston County 18 and 233. West End, Asbury Park, Fort Hancock, Sandy Hook, Mon- 02323213122): ’ngirtl; 2“;ng se 1men ’ as lers, orse Reedy Creek, Brushy Creek, Rocky Creek, Peters Creek, 24' i eneuve ica ine 1n 1 eneuve owns 1p, a so es Beach, Atlantic Beach Duval County ' - 19 miles east of Kosciusko Attala Count ' Kosciusko IEi mouth Count ’ ’ k D'll d C k L 1 c k R' hl d Cr k - . ’ 173. Hicks Dome, Hardin Count ’ y, r g , y . _ - , - . , Abner Cree , 1 ar ree , aure ree , lc an ee , qutlzgld Township f N . k’ 124- Melbcurne, Eau Gallic, Cocoa Beach _ . 174‘ Boaz, Massac County; Kafnak, Olmsted, Pulaski County; Black River, Attala County; Walnut‘Grove, Carthage, 234. ngbee Beach, Cape May, Sea Island City, Wildwood, Cape 265‘ Mggdifeilt: Ifiiltgxggf‘: giggling)goding'egklvgiossglrrgigtr’ Conestee Lake, Long Branch Piedmont, 'Woodv1lle, Huff 25. Leplne epot nor't o aniwa i 125. Vero 3each, Winter Beach, Indian River County, dune sand, Sandusky Cairo Alexander County Thomastown, Leake County; Harpeerlle, Scott Count]; May County R _ C k H . , C k H t' 7C k P 1v Creek, Saluda River, Batesvfle, SimpsonVllle, Paris Moun- 26' AmheFStl crystalline graphite veins . . FortPierce, St‘ Lucie County, littoral sediment . 175. West Chicago area McHenry County Lexington, Holmes County; locality east of Pickens-Cantm 235. Seaside Park, Island Beach, Surf City, Ocean County CobinsoWn bias 7 kefiveners Creek,Chun 111“?) reg/1’ utzz. e tain, Mountain Creek, Greemlle County; Liberty, Pickens 27. Lac Pied des Monts in Die Sales Township, Charlevmx County 126. Trail Ridge near Starke, Highland, Clay County, fossfl placers 176 Gladstone Henderson Count highway, Madison County 236. Tucker Island, Little Egg Inlet, Ocean County; Brigantine, reek, . e ree , uncans ree urc ’. iney oun tam, County; Honea Path, Andersm County; Reedy River east 28. Grand-Calumet Township, skarn 127. Amelia Island, St. Marys Entrance, Fernandina Beach, Nassau ' ’ y 204. Columbia area, Marion County Atlantic County Tfim incl: Moun‘lclaig, JZCkRMOOIM Moun(‘§a1n,kM‘(}i‘}intt (Flwkt of Princeton, Gray Court, Laurens County; Pelzer, Grove 29. IledAlma, Lake St. John County County _ 205. Greenville, Washington County New Mexico C urc , opewe , an y un, ayne ree , es 0r , Creek Hurricane Creek, Bir Creek, Anderson County; 30. East Angus 128. Anastasia Island, South Beach, St. Augustine, Matanzas Inlet, Indiana 206. Vicksburg, Warren County . ' _ ' . . _ Grog Creek, Hinton Creek-Sally Queen Creek, NOYth Fork, Donalds Turkey Creek Abbryille County' Walnut Creek, Saskatchewan St Johns County 177. Michigan City, La Porte County 207_ Natchez, Adams County 237. PeXaCPbMMmtaltn'dIStggt lgcludlng Ehe gunash/IMountalnsI:1 Réo IS‘jonli‘eys Crafké Hafidléargalg CrfielB Beatty CCre:k,é\/Itl)llly Ware Shoals Greenwoyod County, Enoreis River, Durbin . . . _ . 129. Upper Matacumba Key, Monroe County 2 _ ~ - - - h' 1 - t rm 3 oun alns, JO alente, aw one ountaln, r1 - or , ou ree , rler ree , unca-ns ree , 0 1S, ’ . L 3’; graglngCityRarea, gfaverflcodgg area, vein, gneiss 130. Flager Beach Flagler County' Daytona Beach Volusia Iowa M 38 Cat Island, MISSISSIPPI Sound, S 1p IS and, Harrison Coun y lund, the Cribbensville, Silver Spur, North Star, Freetland, Rutherford County, fluvial sediment, schist, gneiss, quartz gglelilgfgggggriggzg gulf?CgeEEeFSrYI:llSTiliTSnMipleaCld:erks ‘ on _ u- ac lver, ony apl s Count ’ i , , on ana Coats Pinto Verde Globe Alamos Apache Nambe and monzonite pegmatite ’ ' ,' ’ . ' ’ ' ' y ' ' . . - . ' - ’ - ’ ’ ’ . ’ . C k B C k, L tl C k, H Creek, North 33' Saskatchewan RN” 131. Olympia Beach, Martin County; Jupiter, Riviera Beach, Palm 3; NVortthUleertyFi, Jolciiisocn Cotuntly, loess (futililtln 209. Sheep Creek, Lost Horse Creek near Hamilton, Ravalll County Capltan pegmatite dGPOSItS,-RIO Grande at Embuda, Chama 266. Sandy Ridge, Dan River, Faggs Creek, North Double Creek, figgfin rCefedk Slgiirth IRezbonxCrEekreRabonmCiiek Fountain Yukon Territory Beach County 180' BeTlsevuéllgghksoy:0311113711138 oess an 1 carbonatite, granodiorite; Victor and McCalla area, Rye River at Ablqulu, Rio Arrlba County, pegmatite, fluvial Danbury, Big Creek, Stokes County, gnelssic granite, fluv1al Inn Lake Greenwood Greenville County Laurens County; 34. Boulder Creek, Clear Creek, McQuesten River, Mayo District; 132. Boca Raton, Palm Beach County ' ’ ’ Creek, Ravalll County, Trail Creek, Beaverhead County, usedlment; Harding mine, Taos County . . . _ sediment . . . . Walnut Creek, Laurens County; Big Brushy Creek, Pickens also accessory in granite 133. Hollywood Beach, Dade County K t k f1uv1a1 sediment 238. Pldllte mine, Mora County; Elk Mountain district, Rlbera 267. Mount Airy, Dobson, Ararat River, Fisher R1ver, Mitchell County“ Broad Mouth Creek Little Creek Tony Creek 134' Miami Beach, Dade County en uc 37. . 210' Elkhorn Peak, Jefferson County, alaskite district, Manzanares Creek area, San Miguel County, peg- River, Surry County, gneissic granite, fluvial sediment Anderson Count ’ ' ' GREENLAND 135. Pensacola Bay, East Bay south of Milton, Florosa, Camp 181- Hickman, Fulton County 211. Deer Creek area including Limekiln Canyon, North Fork of matite; Pecos, San Miguel County, undescribed vein; Lost 268. High Rock area, Rowan County and Davidson County y _ ‘ . C 35. Julianehaab' district, Kvanefjeld area, nepheline syenite, Walton, Santa Rosa Island, Santa Rosa County . . Deer Creek, Bell Canyon, Beaverhead County Creek, area near San Geronimo, and area southwest of Las 269. Rolesville, Milburnie on the Neuse River, Garner, Wake 294- CFPWdeTS Creek, Allison Creek, Y0Y1§f9unt§jgl~illlfélcomity syenite, luJavrite 136. Philli s Inlet Inlet Beach Ba Count and Walton Count 1101115131151 212. Roundup, Devils Basin, Musselshell County, fossil placer Vegas, San Miguel County, unknown mode of occurrence; County, granite 295- Wlnnslwroi R1011: Anderson Quarry, 311’57 all" 19 0’1an ' p i , y y y, ‘ ' ' ‘ ' t ' N b N b C unt ranlte and nelss 36- Egedesmlnde littoral sediments; Haseman, Choctawhatchee Bay, Walton 182. Fullerton, Vernon Parish; Merryville, Beauregard Parish 213- Choteau, Teton County, fOSSli placer Bull Creek area, San Miguel County; Dalton Creek area, 270- Loulsburg, Franklin County; Warrenton, Norllna, Warren granre, ew erry, ESWI edrryR 0 3,} f R' gE t HONDURAS AND BRITISH HONDURAS County, fossil placer 183, Angola, West Feliciana Parish 214. Great Falls, Cascade County, fossil placer Santa Fe County; Los Cerrillos, vicinity of Tuer and Arroyo, County, granite . . 296. ColumbiaI Broad RIVeI‘, a 11 a lver,‘ La erece 138%, TS - .- 137. Beacon Beach Panama City Crooked Island Bay County 184. Baton Rouge East Baton Rouge Parish 215. Harlowton, Wheatland County, fossil placer Santa Fe County, fluvial sediment 271. Fayetteville, Linden, Wade, Little River, Cumberland County; 0761”, RIChland County, also granite, orig ree , we ve' g; grulllloé Hofidlgatswh H d . 1 ° '1; 138. Tampa, Hillsbhro County , ’ 185, New Orleans: Orleans Parish 216. Cut Bank, Glacier County, fossil placer 239. Organ district, Dona Ana County Smithfield, Neuse River, Coats Crossroads, Black Creek, mile Creek, Edmund, ROCk‘Y Creek, Lexmgton, Lexmgton ' tamn ree ’ r1 IS on uras, a so accessory 1n granl e 139. Cape San Blas St. Joseph Point Gulf County‘ Cape St 186. Freemason Island Chandeleur Island, St. Bernard Parish 217- Princeton, Little Gold Creek, Granite County; Powell County 240- Shiprock area, Barker dome, Hogback monocline, San Juan Benson, Johnston County; Tunington, Buies Creek, Olivia, County, also granite; Ridgeway, Falrfleld County, Camden, MEXICO George, moutli of the Appalachicdla River, Franklin County 187. Southeast Pass, Profit Island, Plaquemines Parish 218. Price, Powder Gulch, Silver Bow County County, fossil placer Spout Springs, Anderson Creek, Harnett County; Sanford, (Sjumtfl‘s Landing, LngOff, Blaney, Kershaw County; Sumter 39. Sierra San Pedro de Martir, Baja California, granodiorite 140. Venice, Sarasota County 188. North Barataria Bay, Plaquemines Parish 219. Norris, Madison County 241. Sanostee, Toadlena, San Juan County, fossil placer Lee County 01m y 297. Ridge Spring, Saluda County; North Fork Edisto River near North, Cooper Swamp, South Fork Edisto River, Four Hole Swamp, Sandy Run, Santee River, Orangeburg County; Beaver Creek, Halfway Swamp, Calhoun County; Colleton County; Hampton County; Allendale County; Bamberg County; Barnwell County; Trenton, Johnston, Edgefield County; McTier Creek, Graniteville, Horse Creek near Langley, Holley Creek, Town Creek, Salley, Wagener, South Fork Edisto River, Aiken, Eureka, Shaw Creek, Aiken County, also granite 298. Dillon, Dillon County; Bennettsville, Pee Dee River, Marlboro County; Chesterfield, Chesterfield County; Flat Creek, Lancaster County; Hartsville, Darlington County; Florence, Florence County; Lucknow, Lee County 299. Cattle Creek, Four Hole Swamp, Ashley River, Dorchester County; Jacks Creek, Santee River, Clarendon County; Cypress Swamp, Back River, Biggin Swamp, East Branch, Santee River, Berkeley County; Goose Creek, Wando River, Charleston County 300. Sampit River, Black River, Georgetown County; Black River, Williamsburg County; Myrtle Beach, Horry County 301. Bull Island, Capers Island, Dewees Island, Isle of Palms, Sullivans Island, Edisto Island, Folly Beach, mouth of North Edisto River, Wadmalaw Island, Cape Romain, mouth of Santee River, Charleston County; Fripp Island, Hunting Island, Prichard Island, Hilton Head Island, Beaufort County South Dakota 302. Keystone district, Harney Peak area, Spring Creek, Penning- ton County, Custer County, also fluvial sediment 303. Tinton district, Nigger Hill area, Lawrence County, also fluvial cassiterite placer Tennessee 304. Tuckaleechee, Blount County, conglomerate; French Broad River, Sevier County and Cocke County, fossil placer Indian Mound, Cumberland River, Stewart County, fossil placer, sinkhole deposit, fluvial sediment Benton County, Carroll County, Henderson County, fossil placer Mississippi River at Memphis, Shelby County 305. 306. 307. Texas 308. 309. 310. La Grange, Flatonia, Ledbetter, Fayette County, sand San Antonio River near McFaddin, Refugio County Colorado River south of Matagorda, Matagorda Peninsula, Matagorda County; Brazos River southeast of Freeport, Brazoria County Neches River southwest of Lufkin, Angelina County Brazos Santiago, Padre Island, Cameron County; Padre Island, Willacy County Padre Island, Kenedy County Padre Island, Kleberg County and Nueces County; Mustang Island, Nueces County; St. Joseph Island, Aransas County Galveston Island, Galveston County; Patton Peninsula, Chambers County Sabine Pass, Jefferson County 311. 312. 313. 314. 315. 316. Utah 317. 318. Emery, Emery County, fossil placer Mount Hillars, Henry Mountain area, Hite, Garfield County, fossil placer, fluvial sediment Escalante area, Garfield County; Rees Canyon, Croten Canyon, Sunday Canyon, Kane County, fossil placer Jensen district, Uinta County 319. 320. Virginia 321. Amelia“ Court House, Amelia County, pegmatite; James River, Goochland County; Chickahominy River, Hanover County; Wilson, Dinwiddie County; Blackstone, Nottoway County; Chesterfield County; Macon, Tobaccoville near the Appo- mattox River,’Powhatan County, granite gneiss, granite Five Mile, Post Oak, Spotsylvania County; Little River, Han- over County, granite gneiss Bracey, South Hill, Mecklenburg County, granite gneiss Cumberland County; Farmville area, Prince Edward County; Madisonville, Red House, Charlotte County; Renan, Birch Creek, Pittsylvania County; Sandy Creek, Halifax County, gneiss, granite gneiss, granite, fluvial sediment Stuart, Ararat River, Dan River, Patrick County; Mountain Valley, Martinsville, Chestnut Knob, Henry County, granite, granite gneiss, aplitic granite, mica schist, fossil placer, fluvial sediment Charlottesville, Albemarle County; Culpeper, Culpeper County; Sperryville, Rappahannock County, quartz mon- zonite, granodiorite gneiss Cape Henry, Princess Anne County 322. 323. 324. 325. 326. 327. Washington 328. Sherman Creek Pass, Columbia Mountain, Sherman Park, Ferry County, pegmatite; Marcus Stevens County, fluvial sediment Freeman, Mica, Chester, Saltese Flats, Sommers clay pit, Spokane County, granite, granodiorite, sillimanite schist, lake beds Happy Hill, Okanogan County Wilmont Bar, Columbia River, Ferry County Columbia River, Douglas County Snake River, Asotin County Seattle gold placer, King County Brush Prairie, Clark County Clallam County Moclips, Grays Harbor County Pacific County 329. 330. 331. 332. 333. 334. 335. 336. 337. 338. West Virginia 339. 340. 341. 342. 343. Wyoming 344. Wetzel County; Tyler County, sandstone Morgantown, Monongalia County; Marion County, sandstone Rowlesburg, Preston County, sandstone Kanawha County, sandstone Marlinton, Pocahontas County, sandstone Bald Mountain district, Sheridan County and Bighorn County, fossil placer, fluvial sediment Grass Creek, Waugh, Hot Springs County, fossil placer Mud Creek, Dugout Creek, Washakie County, fossil placer Lovell, Cowley, Big Horn County, fossil placer Clarkson Hill, Poison Spider, Coalbank Hills, Natrona County, fossil placer Salt Wells Creek, Rock Springs Uplift, Red Creek, Green River, Sweetwater County, fossil placer, fluvial sediment Sheep Mountain, Albany County, fossil placer Cumberland Gap, Uinta County, fossil placer SOUTH AMERICA 345. 346. 347. 348. 349. 350. 351. ARGENTINA 1. Cordoba, Gordoba Province, granite and gneiss 2. Sierra de Valle Fértil, San Juan Province 3. Rio de la Plata, Buenos Aires 4. Orosmayo, Rio Cincel 5. Rio del Candado 6 Riocito at La Carolina, San Luis Province BOLIVIA 7. Mina Verde near San Agustin, Santa Cruz 8. Sorata 9. Chorolque 10. La Union 11. Huayna Potosi 12. Cerre de Llallagua BRAZIL 13. Fazenda Quebra—Cangalha, Sao Paulo 14. Caravelas, Bahia 15. Diamantina district including the Barro—Duro opencut, Sao Joao da Chapada, Serra do Gigante Perpetua, Sopa, Ogo gold mine, Bandeirinha, Riacho Varas, Pagao, Campo do Sampaio, Cavallo Morto diamond mine, Milho Verde, Rio Jequitinhonha, Rio das Pedras, Minas Gerais 16. Rio Doce near Casca, Rio Casca, Minas Gerais 17. Salébro, Canavieiras, Serra do Mar, Rio Pardo, Riacho Salo- brinho, Rio Salobro, Co’rrego do Rico, Gorrego do Desen- gano, Cérrego do Saio J osé, J acaranda, Bahia, also quartzite, gneiss, granite, pegmatite 18. Prado, Bahia 19. Serra de Tijuca, Rio de Janeiro (city), Serra do Mar, Jacare- pagua, Niteroi, Rio de Janeiro (state), granite, gneiss 20. Barra do Pirai, Rio de Janeiro, granite, gneiss 21. S50 Fidelis, Rio de Janeiro, graphite-rich layer in gneiss 22. Consercatoria, Santa Isabel do Rio Preto, Rio de Janeiro, granite, garnetiferous gneiss, pegmatite, fluvial sediment 23. Paraiba do Sul, Rio de Janeiro; Roca Grande mine near Ibiti- guaia, Linhares mine, Municipio Juiz de Fora, Minas Gerais 24. Rio Bonito, Rio de Janeiro 25. Crubixais, Rio de Janeiro, pegmatite; Sosségo, Minas Gerais, sillimanite gneiss 26. Cotia, San Joas, Sao Paulo, sillimanite gneiss, syenite 27. Caieiras, Solo Paulo, muscovite granite 28. Sorocaba, Piedade, Sao Paulo, muscovite granite, biotite granite 29. Santos, sso Paulo, biotite-muscovite gneiss 30. Boa Vista on the Rio Ribeira de Iguapa, S50 Paulo, biotite granite 31. Headwater tributaries to the Rio Paraiba and Rio Paraibuna, Sao José dos Campos, Sao Paulo, gneiss, conglomerate 32. Itapecerica da Serra, 85.0 Paulo, sand 33. Fazenda Recreio southeast of Pinhal, S50 Paulo, granite 34. Grama, S50 Paulo 35. corrego do Emparedado at a point about 65 miles downstream along the Rio Jequitinhonha from Arassuai, Minas Gerais, accessory in graphite layer in gneiss,,pegmatite 36. Datas, Minas Gerais, metaconglomerate, quartzite, schist 37. soo .1vo del Rei area including the basin of the Rio das Mortes, Santa Rita do Rio Abaixo, Morro do Rezende, Cassiterita, Rio das Mortes Pequeno, Fazenda da Barra, Fazenda Rochedo, Ribeirao Jaburu, Fazenda Fundao, Mato Virgem, Ibatuba, Rochedo, Municipio de Resende Costa, corrego do Sobrado south of Rio do Peixe in the Municipio de Passa Tempo, Minas Gerias, also granite, gneiss, eluvium, fluvial sediment 38. Gruta da Generosa near Sabinopolis, Minas Gerais 39. Divino de Uba, Minas Gerais 40. Brejauba, Sao José do Brejal’iba, Fazenda da Posse, Minas Gerais 41. Near Ferros including Lambary de Ferros, Minas Gerais 42. Presidente Vargas, Baréo de Cocais, Minas Gerais; also fluvial sediment 43. Lima Duarte, Sio José de Além Paraiba, Minas Gerais, also fluvial sediment 44. Piracicaba, Minas Gerais 45. S210 Sebastiao do Rio Préto, Conceicao district, Passabem, Minas Gerais, also auriferous quartz vein 46. Tripuhy near Ouro Preto, Emprésa Caolim mine, Estevao Pinto district, Municipio Mar de Espanha, Minas Gerais, mica schist, tungsten vein, pegmatite 47. Rio Paraiba, Barra Sao Francisco near Sapucaia, Fazenda da Arribada and Fazenda Campos Elysios near Mar de Espanha, Minas Gerais 48. Rio Pomba, Rio Muriahé, Serra do Tombas, Serra do Papa- geios, Fazenda Santa Clara near Pomba, Minas Gerais, also pegmatite 49. C6rrego da Onca, Rio Doce near Itarana, Minas Gerais 50. Teofilo Otoni area including the headwaters of the Rio Mucuri, Ribeirao Barro Preto, Cérrego das Americanas, Rio Mutum, Corr’ego da Onca, Cérrego do Surucucu, Minas Gerais 51. Arassuai area including headwater tributaries to the Rio J equitinhonha, Coronel Murta, Minas Gerais; also pegmatite 52. Rio Pancas, Rio sso Joao, Rio Doce, Espirito Santo, gneiss 53. Serra dos Aimorés, Serra da Liberdade, Rio sso José, Espirito Santo, gneiss, vein 54. Lagoa Juparana, Espirito Santo, lacustrine sediment 55. Fazenda Catita, Rio Doce, Espirito Santo, mica syenite 56. Guarapai area including Praia do Vaz, Vila Velha, Rastinga, Canto do Riacho, Praia de Diogo, Ponta da Fructa, Piuma, lconha, Caju and Patriménio deposits, Carapebus, Serra, ‘ "”Cfipuba, Jacaraipe, Vitoria, Espirito Santo, pegmatite at Guarapai, littoral sediment elsewhere 57. Lencois, Bahia, quartzite and conglomerate 58. Born Jesus dos Meiras including Catita Grande do Piraja, Serra das Eguas, Serra do Espinhaco, headwaters of the Rio de Contas, Bahia, druses in marble 59. Morro da Gloria, Itambé, Bahia 60. Serra do Stauba, Bahia, syenite 61. Estrada de Ferro de Nazareth near Ubaira, Bahia, gneiss 62. Bandeira de Mello on the Rio Paraguacu, Bahia 63. Borborema pegmatite district, Sabugui, Paraiba 64. Picui, Paraiba; also fluvial sediment . 65. Capoeiras, Santa Cruz, Rio Grande do Norte 66. Rio Serido, Rio Acu, Sao Rafael, Florana, Acari, Currais Novos, Municipio Sao Bento, Rio Grande do Norte, also granite, fluvial sediment 67. Catalao, Goias; also fluvial sediment 68, Mato Grosso 69. Ilha de Sao Sebastiao, Séo Paulo 70. Praia Massanduba at Cabo Frio, Barra de S50 Joao, Macaé, Retiro, Buena, Samambaia, Ponta da Barrinha, Rio de Janeiro 71. Mouth of the Rio Paraiba, Rio de Janeiro 72. Barra de Itabapoana, Ponta do Siri, Maratayso Praia, Jacunem, Rio Itabapoana, Itapemirim, 30a Vista, Meaipe, Pitas, Mangue, Sacco, Cacurucagem, Quartéis, Tiriricas, Itapicu, Curu, Anchieta, Parati, Imbiri, Pipa de, Vinho, Maéba, Joana near Muquicaba, Uba, Espirito Santo 73. 850 Mateus, mouth of the Rio 8210 Mateus, Espirito Santo 74. Nova Almeida 75. Mouth of the Rio Doce at Regencia, Espirito Santo 76. Month of the Rio Mucuri, Mucuri, Porto Alegre, Riacho das Ostras, Barra Nova, Maroba, Alcobaca, Bahia 77. Cumururatiba, Comoxatiba, Cai, Barreira, Itapara, Dois Irmaos, Corrego do Ouro, Rio do Peixe, Ponta do Paixao, Pon'ta da Barreira, Bahia 78. Ponta Juacema, Caraiva, Bahia 79. Porto Seguro, Trancoso, Santa Cruz, Nossa Senhora da Ajuda, Rio da Villa, Toque-Toque, Rio sso Francisco, Rio Santa Cruz, mouth of the Rio Jequitinhonha, Bahia 80. Cunhau, Paraiba do Norte BRITISH GUIANA 81. Kamiku Mountains, Rupununi River district between the Takatu River and Rupununi River, including Wabwak Mountain, Marmiswau River, Moriwau River, Tutuwau CHILE Creek, Wuratwau Creek, also accessory 1n Silllmanlte gneiss 82. Punta Catizo-Punta Checo area, Isla de Chiloé 83. Rahue-Cucao area, Isla de Chiloé 84. Pumillahue, Isla de Chiloé 85. Ancud-Chacao area, Isla de Chiloé COLOMBIA 86. Rio Chico, Antioquia 87. Zaragoza FALKLAND ISLANDS 88. Littoral sediment FRENCH GUIANA 89. Courcibo River, Leblond Creek, Sinnamary River 90. Cayenne PERU 91. Rio Pacasmayo, Pacasmayo 92. Sechura 93. Tarcominas mine near Pampacolca, Castilla, Departmento de Arequipa SURINAM 94. Cassipora on the lower Suriname River, granite 95. Damanallé on the Pikien Rio, Goddo on the Gran Rio, por- phyritic biotite granite 96. Awa fall on the Gran Rio, porphyritic biotite granite 97. Paloemeu River, Kassikassima, Tapanahony River, granite 98. Longoston on the Coppename River, granite gneiss 99. Locality 25 miles south of Paramaribo URUGUAY 100. Punta Caballos 101. Atlantida 102. La Floresta, Costa Azul, San Luis 103. Solis, Bella Vista 104. La Pedrera 105. Aguas Dulces 106, La Coronilla VENEZUELA 107. Potreritos Ranch, District of Bolivar, Zulia,sandstone Base from US. Naval Ocean chart 5188A. Boundaries a ographic Office re shown as of January 1, 1962, and should not be regarded as having official significance MAP SHOWING DISTRIBUTION OF MONAZITE IN NORTH AMERICA, SOUTH AMERICA, AND 500 O 500 1000 1500 2000 MILES ,__, i j. m . 500 O 500 1000 1500 2000 KILOMETERS L—l le—l l~—l ' .' l——————-——l MERCATOR PROJECTION SCALE 1:26 000 000 AT EQUATOR INTERIORfiGEOLOGICAL SURVEY. WASHINGTON. D C 71967 —G65254 THE WESTERN PART OF AFRICA Compiled by William C. Overstreet, 1962 575/ 7 DAY 67 53/ E“-‘L'fi‘Ehitons and Gastropods (Haliotidae Through Adeorbidae) . From the ' Western Pacific Islands GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 Chitons and Gastropods (Haliotidae Through Adeorbidae) From the Western Pacific Islands By HARRY s. LADD GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 Description and preliminary paleoeeologic in- terpretations offossilmollnsks from seven island groups UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director I4ll)l‘:ll'}' Hf (‘ungn-ss (analog-curd Nu, GS 66457 For sale by the Superintendent of Documents, U.S. Government Printing Oflice Washington, D.C. 20402 - Price $1.25 (paper cover) CONTENTS Page Abstract ______________________________________________ 1 Paleontology—Continued Introduction ___________________________________________ 1 Paleoecology _______________________________________ Area and localities _________________________________ 1 Faunal relations """"""""""""""""""" Purpose and scope __________________________________ 1 Systematlc paleontology ———————————————————————————— Earlier references to fossil mollusks _________________ 3 Chitons """"""""""""""""""""""" Palau _________________________________________ 3 Schizochitonidae ___________________________ Mariana Islands _______________________________ 3 Chitonidae """"""""""""""""""" Marshall Islands _______________________________ 3 Acanthochitonidae _________________________ Ellice Islands __________________________________ 3 Gastr°P9d§ ------------------------------------ Funafuti ___________________________________ 3 HahOtlda? """""""""""""""""""" New Hebrides _________________________________ 3 Scissurellldae """"""""""""""""""""" Fiji 4 Flssurellidae _______________________________ """""""""""""""""""""""" Patellidae _________________________-__--__- Tonga ————————————————————————————————— 5 T rochidae _________________________________ Collections ———————————————————————————————————————— 5 Stomatellidae _______________________________ Acknowledgments __________________________________ 6 Angariidae (Delphinulidae) __________________ Geology _______________________________________________ 6 Turbinidae ________________________________ Stratigrapliy _______________________________________ 6 ‘ Phasianellidae ______________________________ Eocene ________________________________________ 7 Neritopsidae _______________________________ Oligocene _____________________________________ 8 Neritidae __________________________________ Miocene _______________________________________ 8 Littorinidae ________________________________ Post-Miocene __________________________________ 8 Irevacllldae ________________________________ . Rlssouiae _________________________________ P11909119 """""""""""""""""""" 9 Assimineidae _______________________________ Pleistocene and Recent ————————————————————— 0 Adeorbidae (Vitrinellidae) __________________ Correlation ________________________________________ 9 Localities ______________________________________________ Paleontology ___________________________________________ 9 References ____________________________________________ Geographic and geologic distribution of species ________ 9 Index _________________________________________________ Page 11 15 20 21 21 23 24 25 25 26 27 32 33 41 42 43 53 55 55 59 59 60 75 75 81 89 93 iii ILLUSTRAIIONS [Plates follow index] PLATE 1. Chitons. 2—16. Gastropods: FIGURE 3. 2. Haliotidae, Scissurellidae, and Fissurellidae. 3. Fissurellidae, Patellidae, and Trochidae. 4. 4. Trochidae. 5.‘ Trochidae, Stomatcllidae, and Angariidae. 5—8 6—9. Turbinidae. lO. Phasianellidae, Neritopsidae, Neritidae, and Assimineidae. 11. Neritidae, Littorinidae, Iravadiidae, and Rissoidae. 12,13. Rissoidae 944 14. Rissoidae and Adeorbidae. 15,16. Adeorbidae. Page FIGURE 1. Index map showing location of island groups __ . i 2 2. Sketch map showing fossil localities in the Goikul area, Palau ________________________ 81 l TABLES . Geologic distribution of species _____________________________________________________________________________ . Living Indo-Pacific mollusks that also occur in the upper Tertiary sediments of the island area __________________ Sketch map of Guam, Mariana Islands, showing localities mentioned in text, ________________ Sketch map showing fossil localities on Selipan, Mariana Islands __________________ . Maps showing locations of drill holes: 5. Eniwetok Atoll ________________________ 6. Eniwetok Atoll ________________________ 7. Bikini Atoll __________________________ 8. Funafuti Atoll ________________________ . Maps showing fossil localities: 9. New Hebrides ________________________ 10. Viti Levu, Fiji ________________________ 11. Fulanga, Lau, Fiji ____________________ 12. Ongea, Lau, Fiji ______________________ 13. Lakemba, Lau, Fiji ____________________ 14. Tongatabu, Tonga _____________________ 1. Distribution of Cenozoic sediments in the island area _________________________________________________________ 2. Major stratigraphic subdivisions recognized in holes drilled in the Marshall Islands _______________________________ 3. Correlation of Cenozoic units in the island area _____________________________________________________________ 4. Geographic distribution of species ___________________________________________________________________________ 5 6 Page 82 84 86 87 87 88 88 89 89 Page 7 7 10 12 16 20 CHITONS AND GASTROPODS (HALIOTIDAE THROUGH ADEORBIDAE) FROM THE WESTERN PACIFIC ISLANDS By HARRY S. LADD ABSTRACT Cenozoic mollusks from seven island groups in the western Pacific are treated systematically. The islands form a broad belt spreading 4,000 miles across tropical latitudes from the Mariana Islands and Palau on the northwest through the Marshall, Ellice and New Hebrides groups to Fiji and Tonga on the southeast. Each of the island groups has a section of Quaternary limestones and all except the Ellice group are known to have a Tertiary sequence as well. The known Tertiary in all island groups, except that in the New Hebrides, extends back as far as the Eocene. No Paleocene rocks have been recognized. Two hundred and eight species and subSpecies are described. These include representatives of 3 families of chitons and 16 families of gastropods (Haliotidae through Adeorbidae). Three new subgenera of gastropods are described: Vitiastraea (sub- genus of Astraea), Subditotectarius (subgenus of Tectarius), and Ailinzebina (subgenus of Zcbina). Sixty-seven new species and five new subspecies are described. The species discussed in the present report comprise approximately one-sixth of available collections. About three-fourths of the new forms were recovered from the drill holes in the Marshall Islands; the remainder, from outcrop samples, are divided almost equally between Palau and Fiji. A few of the new forms from the Marshall Islands also occur in Palau and Fiji. The richest and most widespread assemblages are Miocene (Tertiary f and {1). Most of the mollusks are reef associated. Many, notably those of the limestones in the deep drill holes of the Marshalls, Occur in beds that were deposited in lagoons; some species occur in beds that were accumulated on tidal flats; a few species lived in fresh or brackish waters. The assemblages of fossil mollusks, like those living in the area today, are Indo-Pacific in general aspect. The strongest dis— cernible ties are with living and fossil faunas of tropical Indo— nesia, rather than with faunas from more southerly areas (south- ern Australia and New Zealand) or more northerly areas (the Ryukyu Islands and Japan). Thirty—three of the des'a'ibed species that still live in the island area have been there at least since late Tertiary time. Of this group, the shells of 25 were recovered from Marshall Island drill holes, those of 10 from outcrops in Fiji. A few species that lived in the island area during the Tertiary are now living only in other parts of the Indo-Pacific region. Numerous living Indo-Pacific species had close relatives, some perhaps ancestral, in the island area during the upper Tertiary. In the Miocene of Bikini is a species of Pisulina, a genus known previously only from a few species living near India and Ceylon. The nearest relatives of a lower Miocene (lg/Izisca of Eniwetok live off the Cape of Good Hope, South Africa. Schizuchilml, the reef chiton that lives today in the Philippines and northern Aus- tralia, had representatives in the Marshall Islands and Palau during the Miocene. Ties between the island area and the Americas are suggested, but they are less impressive than rela- tionships with the Indo—Pacific. INTRODUCTION AREA AND LOCALITIES The islands of the western Pacific considered here form a broad and somewhat irregular belt spreading 4,000 miles across the tropical latitudes of the western Pacific, from the Mariana Islands and Palau on the northwest to Fiji and Tonga on the southeast (fig. 1). The belt measures approximately 1,000 miles in width and includes seven island groups—Marshall, Ellice, Mariana, Palau, New Hebrides, Fiji, and Tonga. Of these, only the Marshall and Ellice Islands lie in the Pacific Basin proper, within the circum-Pacific 'andesite line. As thus outlined, the belt includes all of Micronesia and eastermost Melanesia and separates Indonesia from most of the Pacific Basin proper. PURPOSE AND SCOPE This primarily paleontologic report deals mainly with large collections of fossil mollusks obtained by the US. Geological Survey and other governmental agencies dur— ing field investigations in Micronesia in the years im- mediately following World War II. These investigations were of two types: 11.! Deep drilling at Bikini Atoll in connection with Operation Crossroads in 1947 and at Eniwctok Atoll for the Atomic Energy Commission in 1951—52; all deep drilling was under the supervision of US. Geological Survey personnel. (2) Detailed mapping projects carried on by the US. Geological Survey under the sponsorship of the US. Army, Corps of Engineers, in Palau, 194748, Saipan, 1948—49, Tinian, 1949—51, and Guam, 1951—54. The Survey’s collections from Guam supplement even larger collections made earlier by the Pacific Island Engineers under contract with the US. Navy. In an attempt to make the study of island fossil mol- lusks as complete as possible, collections from other island groups—Fiji, Tonga, New Hebrides, and Ellice Islands—have been reviewed. Some material from these islands, already described in print, has been reexamined. 1 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS 3 l . . .u - i, . ‘ EAsrrweIGRE men wisrmon sazzmmcn . l . ELLICE.. _ 'NEW - r ‘ \ HEBRIDES ‘ . M . ,. . ‘ , . \ ’ FIJI I‘; '5; i . \ \ . \ \ m \ '\ \ I\ ' Florin: 1.—Location of island groups from which fossil mollusks have been obtained. Dashed line marks structural boundary of Pacific Basin (andesite line). The mollusks living in the western Pacific island area today are closely related to those of Indonesia, and a study of fossil forms should have some bearing on ques- tions involving origin and migration. Preliminary state- ments of age, correlation, and paleoecologic interpreta- tion are given in this paper, but a full discussion of these matters and detailed interpretations of regional relations of the faunas are reserved for a later paper. INTRODUCTION 3 EARLIER REFERENCES TO FOSSIL MOLLUSKS Published papers that. contain identifications or de- scriptions of fossil mollusks from the island under con— sideration are briefly annotated and arranged chron- ologically under island groups below. PALAU 1951. Hatai, Kotora, Fossil Mollusca from Angaur Island: Inst. Geology and Paleontology, Tohoku Univ., Short paper 3, p. 127. Collections made by R. Tayama contain a dozen forms. Five are identified with Recent species, and it is concluded that the beds are probably post-Miocene in age. MARIANA ISLANDS 1956. Gardner, Julia, in Cloud, P. E., Jr., Schmidt, R. G., and ' Burke, H. W., Geology of Saipan, Mariana Islands: US. Geol. Survey, Prof. Paper 260-A, p. 47, 60, 66—67, 80—81, 86—87. Preliminary reports on collections of fossil mollusks from Tertiary and younger rocks of Saipan. From the Eocene (Hagman Formation and Matanzas Limestone) a few generic references; from the Miocene (Tagpochau Limestone) 29 mollusks named, 13 being specifically identified or compared with named species; from the Pleistocene (Mariana and Tanapag Limestones) 30 mol- lusks, of which 19 are identified specifically or compared with described species. Molluscan fauna of Mariana Limestone probably represents older Pleistocene. MARSHALL ISLANDS 1954. Ladd, H. S., in Emery, K. 0., Tracey, J. 1., Jr., and Ladd, H. 8., Geology of Bikini and nearby atolls, Marshall Islands: US. Geol. Survey Prof. Paper 260-A, p. 80— 84, 90. Fossil mollusks from seven intervals in upper 300 feet in deep drill holes identified with species living in existing lagoons of Bikini and Eniwetok. Mollusks from 925 to 935 feet recognized as appreciably older shallow- water fauna. 1957. Ladd, H. S., and Tracey, J. 1., Jr., Fossil land shells from deep drill holes on western Pacific atolls: Deep-Sea Research, v. 4, no. 3, p. 218—219. Records occurrence of four species of minute land snails in Miocene and younger rocks of atolls, including Bikini and Eniwetok. Because the shells belong to a genus (Ptychodon) that normally lives on forested is- lands well above sea level, their occurrence suggests that the present-day atolls periodically stood above sea level, functioning as stepping stones in the distribution of life. 1958. Ladd, H. 8., Fossil land shells from western Pacific atolls: Jour. Paleontology, v. 32, no. 1, p. 183—198. Descriptions of fossil endodont land snails (Ptycho- don) including three species obtained from Bikini and , Eniwetok from lagoonal deposits now 170—1800 feet be- 1 low sea level. Ages ranges from Miocene (Tertiary e) to Pleistocene or Recent. 1960. Ladd, H. 8., Origin of the Pacific Island molluscan fauna: Am. Jour. Sci. Bradley volume. 258-A. p. 137—150. Summarizes data supporting a suggestion that many elements of the Indo-Pacific fauna may have originated in the islands in Cretaceous and Tertiary times and later migrated with aid of prevailing winds and currents to west and southwest. 1960. Ladd, H. 8., and Schlanger, S. 0., Drilling operations on Eniwetok Atoll. U.S. Geol. Survey Prof. Paper 260-Y, p. 863—903. Includes generic identifications of mollusks in series of drill holes, deepest of which reached upper Eocene (Tertiary b). " 1960. Ladd, H. 8., Distribution of molluscan faunas in the Pa- cific islands during the Cenozoic: U.S. Geol. Survey Prof. Paper 400-B, p. B374—B375. Brief summary of known occurrences of fossil mol- lusks in six island groups in the western Pacific. ELLICE ISLANDS FUNAFUTI 1904. Hinde. G, J.. Report on the materials from the borings at the Funafuti Atoll, in The Atoll of Funafuti: Royal Soc. London, p. 187—361. A few of the sands obtained from the upper parts of the drill holes contain rare but well-preserved shells of micromollusks, and many of the cores from lower levels show molds of larger mollusks. A few generic determi- nations made by E. A. Smith and others are cited, but in most places molluscan occurrences are recorded merely as casts of gastropods or lamellibranchs. 1957. Ladd, H. S., and Tracey, J. 1., Jr., Fossil land shells from deep drill holes on western Pacific atolls: Deep-Sea Research, v. 4. no. 3. p. 218-219. Cites occurrence of species of Ptychodon in sample obtained from holes drilled in post-Miocene reefs. 1958. Ladd, H. 8., Fossil land shells from western Pacific Islands: Jour. Paleontology, v. 32, no. 1, p. 183—198. PLychodon sp. A is described and figured from par- tially leached coralliferous limestone from a drill hole at a depth of 166—170 feet. Age, Pleistocene or Recent. NEW HEBRIDES 1905. Mawson, Douglas, The geology of the New Hebrides: Linnean Soc. New South Wales Proc., v. 30, p. 400—485. Includes reference (by number) to occurrences of fossil mollusks identified by Charles Hedley and listed in appendix. 1905. Hedley, Charles. Determinations of Mollusca, in Mawson, Douglas, The geology of the New Hebrides: Linnean Soc. New South Wales Proc., v. 30, p. 477—478. Lists 82 generic and specific determinations of mol- lusks believed to range in age from Pliocene to Recent. Several are considered to be new but are not described. Some forms thought to have lived beyond intertidal levels, perhaps as deep as 15 fathoms. 1937. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Abrard, Rene. and La Riic, E. A. de, Sur l’existence du Néogene supérieur a Cycloclypeus aux iles Epi et Male- kula (Nouvelles-Hébrides): Acad. sci. [Paris] Comptes l'(‘nllllS. v. 204. no. 25. p. 1951—1953. Nine fossil mollusks are identified with Recent Indo- l’acific species, four with fossil forms described by Ladd from Viti Levu, Fiji, two with Miocene species from Java; 17 others appear to be undescribed. 1937. Abrard, René. and La Rue, E. A. de, Sur la présence du 1938. Pliocene a l’ile Malckula (Nouvelles Hebrides): Acad. sci. [Paris] Comptes rendus. v. 205, no. 4, p. 290—292. A total of 31 mollusks are identified with Recent species or compared with such forms. Three others are recognized as new, and three are identified with species from the Pliocene of Java. The beds are assigned to the Pliocene. Abrard. René, and La Riie, E. A. de, Note sur les depots Quaternaires et les ré’cifs soulevés du Nouvelles-Hébrides: Soc. géol. France Bull, v. 8, p. 63—66. Twenty-five generic and specific identifications of mollusks are reported from elevated limestone on Efate; age probably Quaternary but possibly Pliocene. Nine- teen mollusks are listed from similar limestones on Eromanga. 1946. Abrard, René, Fossiles Néogenes et. Quaternaires des Nou- 1880. Woods. J. velles-Hébrides: p., 5 pls. Annales de paleontologie, v. 32, 112 Detailed and well-illustrated report on large collec- tions of mollusks (126 species) and other fossils made by E. A. de La Riie from Miocene and later rocks at Malekula, Epi. Efate, and Eromanga. Close ties estab- lished to Miocene of Fiji. FIJI E. T., On some fossils from Levuka, Viti: Linnean Soc. New South Wales Proc., v. 4, p. 358—359. Several fossils, including mollusks, said to have been collected from the center of Ovalau, exact locality un- known. No specific identifications were made, but some of the mollusks were compared with Miocene species of Australasia. The fossils were imbedded in clay and sandy clay. [No rock of this type has been reported from Ovalau, and it seems probable that the material was collected from the marls of nearby Viti Levu. H.S.L.] 1898. Dall, W. H., in Agassiz, Alexander, The Tertiary elevated limestone reefs of Fiji: p. 165. Contains identification of examples of 10 still-living genera of mollusks. Expresses the belief that the rock is probably younger than Eocene. possibly Miocene or Pliocene. Am. Jour. Sci., 4th ser., V. 6, 1900. David, T. W. E, Preface to geological report by E. C. Andrews: Harvard Coll. Mus. Comp. Zoology Bull.. v. 38. p. 5—10. Mentions occurrence of large Tridacna in conglomerate exposed at Walu Bay on Viti Levu that suggests an age not older than late Tertiary. 1903. Woolnough, W. G., The continental origin of Fiji: Linnean Soc. New South Wales Proc., v. 28, p. 457—540. 1907. Woolnough, W. G., A contribution to the geology of Viti 1903. 1918. 1926. 1927. 1930. 1934. Levu, Fiji: Linnean Soc. New South Wales Proc., v. 32, p. 433—474. Though Woolnough collected no specifically identifi- able fossil mollusks, he records the occurrence of frag- mentary shells of Conus and Pecten, believed to be Tertiary, at localities in the then little known interior of Viti Levu. [These clues led later workers to well- preserved molluscan faunas. H.S.L.] Guppy, H. B., Vanua Levu, v. 1, of Observations of a naturalist in the Pacific between 1896 and 1899: Mac- millan and C0,, 392 p. Generic identification given for pelecypods in shell bed elevated a few feet above the sea, in limestones and in tuffs, some of the tuffs now lying more than 2.000 feet above sea level. Foye, W. G., Geological observations in Fiji: Am. Acad. Arts and Sci. Proc, v. 54, no. 1, p. 1—142. On page 86 there is a list of 15 generic identifications of mollusks as made by Paul Bartsch; the genera are common tropical forms, each being followed by a query; Foye collected the material from three localities on Viti Levu. Mansfield, W. C., Fossils from quarries near Suva, Viti Levu, Fiji Islands * * * with annotated bibliography of the geology of the Fiji Islands: Carnegie Inst. Wash- ington Pub. 344, p. 85—104. Description of 4 gastropods and 14 pelecypods (in- cluding 3 new species). Tertiary age suggested, prob- ably late Miocene or early Pliocene. Matley, C. A., and Davies, A. M., Some observations on the geology of Viti Levu: Geol. Mag. [Great Britain], v. 64, no. 752, p. 65—75. Includes description of supposed fresh-water clam, Nodularia vitiensis Davies, from the marls above Nasongo; beds probably Tertiary, possibly Miocene. Davies, A. M.. Fossils from Viti Levu: Geol. Mag. [Great Britain], v. 67, no. 787, p. 48. Molds of bivalves from near Nasongo, referred in 1927 (Matley and Davies) to the fresh water clam Nodularia, are reassigned to marine Mactracea. Ladd, H. S., in Ladd and others, Geology of Vitilevu, Fiji: B. P. Bishop Mus. Bull. 119, 263 p. One hundred and twenty-two mollusks (53 pelecypods, 3 scaphopods, 1 chiton, and 65 gastropods), most of which were collected during reconnaissance surveys in 1926 and 1928, are described and most of them figured; they are from beds ranging in age from Miocene to Recent. Brief discussion of paleoecological conditions. 1945. Ladd. H. S., in Ladd and Hoffmeister, J. E., Geology of Lau, Fiji: B. P. Bishop Mus. Bull. 181, 399 p. Seventy-six mollusks, half pelecypods and half gastro- pods, most of them collected during a reconnaissance INTRODUCTION 5 survey in 1934, are described and many figured; they are from beds ranging in age from Miocene to Pleisto- cene. Brief discussion of paleoecological conditions (by Ladd and Hoffmeister). 1959. Charig, A. J., in Bartholomew, R. W., Geology of the Lau- toka area north—west Viti Levu: Suva, Fiji, Geol. Survey Dept. Bull. 2, 25 p., geol. map. Sixteen mollusks, 3 pelecypods and 13 gastropods, are identified by A. J. Charig and C. P. Nuttall (p. 18—19) from two localities in bedded tuffaceous sediments mapped as part of the Sambeto series. Twelve fossils are identified with still-living species, three others are com— pared with such forms. Only one species appears to represent an extinct species though several are known to occur as fossils in the Pliocene or later. A Pliocene age is thought probable, a late Miocene age possible. 1960. Ibbotson, Peter, Geology of the Suva area, Viti Levu: Suva, Fiji Geol. Survey Dept. Bull. 4, 47 p., geol. map. Detailed report on quarter-degree sheet in south- eastern Viti Levu that includes many of the late Ter- tiary localities in the Suva Formation that have yielded fossil mollusks. Identifications of Mansfield (1926), Davies (1927, 1930), and Ladd (1934) are listed. 1960. Bartholomew, R. W., Geology of the Nandi area. western Viti Levu: Suva, Fiji Geol. Survey Dept. Bull. 7, 27 p., geol. map. A list of fossils identified by L. R. Cox in 1954 (p. 11) includes six molluscan generic determinations. 1961. Ibbotson, Peter, Geology of Ovalau, Moturiki and Nain- gani: Suva, Fiji Geol. Survey Dept. Bull. 9, p. 1—7, geol. map. Quotes in full, Tenison-Woods’ brief report of 1897, pointing out that it is the only report on fossiliferous material from Ovalau. 1963. Charig, A. J., The gastropod genus Thatcheria and its re— lationships: British Mus. (Nat. History) Bull., Geol. v. 7, no. 9. p. 257-297. Includes description of Thatcheria vitiensis from iuffaceous marl of Vanua Levu Formation on Vanna Levu; age probably early Pliocene. 1963. Rickard, M. J.. The geology of the Mbalcvuto area: Suva. Fiji Geol. Survey Dept. Bull. 11, 36 p., geol. map. Includes references (p. 30—33) to mollusks, identified by H. S. Ladd. from the Singatoka. Suva, and Mba series of upper Tertiary area. 1965. Ladd, H. S., Tertiary fresh-water fossils from Pacific islands: Malacologia v. 2, no. 2, p. 189—198. Includes description of a. species of Melmmides from beds formed in mangrove swamp on Viti Levu in late Tertiary time. TONGA 1926. Mansfield, W. C., Fossils from ‘t 1‘ * Vavao, Tonga Islands * ‘k *: Carnegie Inst. Washington Pub. 344, p. 85—104. Three mollusks, one identified with a living species and one related to a living form. are listed, and a post- Tcrtiary age is suggested. 1932. Hoffmeister, J. E., Geology of Eua, Tonga: B. P. Bishop Mus. Bull. 96, 93 p. Records the occurrence of the nautiloid Aturia (p. 33) in bedded volcanic tuffs believed to be Miocene in age. 1935. Ostergaard, J. M., Recent and fossil marine Mollusca of Tongatabu: B. P. Bishop Mus. Bull. 131, 59 p. A total of 39 fossil mollusks (26 gastropods and 13 pelecypods) from Tongatabu and Vavau are identified with Recent species. Limestones containing fossils be- lieved to be late Pleistocene in age. 1941. Miller, A. K., An Atmia from the Tonga Islands of the central Pacific: Jour. Paleontology, v. 15, no. 4. p. 429—431. Specimen collected by J. E. Hoffmeister from tuffs, believed to be Miocene, is described and figured as Atm‘ia cf. A. mini (Basterot). COLLECTIONS Most of the collections on which the present study is based were made by US. Geological Survey personnel; others were loaned for study by museums and other in- stitutions. All important sources are given below: Palau.——Most of the Palau material was collected by i H. S. Ladd in 1958; other collections had been made earlier by several Geological Survey geologists, par- ticularly in 1948 by a party headed by the late Arnold Mason. Mariana Islands—The largest collections of megafos- sils from any of the islands under consideration were made from Guam by the Pacific Islands Engineers under contract with the US. Navy in 1946—50; supplementary collections from Guam were made by a Geological Survey field party under the leadership of J. I. Tracey, Jr., in 1951—54 and by H. S. Ladd in 1958. Most of the Saipan material was collected by a Geological Survey field party headed by P. E. Cloud, Jr., in 1948—49, and minor addi- tions were made by H. S. Ladd in 1958. The few fossil mollusks that have been obtained from Tinian were col- lected by the late Josiah Bridge in 1946 and by Cloud in 1949, both of the Geological Survey. Marshall Islands—Cores and cuttings were obtained from drill holes on Eniwctok and Bikini Atolls between 1947 and 1952. Ellice Islands.——C_orcs and cuttings from drill holes obtained by the British on Funafuti Atoll between 1896 g and 1898 (David and others, 1904). Material was bor- rowed from the British Museum (Natural History), the Australian Museum in Sydney, and the Museum of Com- parative Zoology at Harvard. New H chides—Small collections were made by H. T. Stearns of the Geological Survey in 1943; some material 6 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS was borrowed from M. R. Abrard of the Museum Na- tional d’Histoire Naturelle in Paris. Fiji—The collections of larger mollusks described by Ladd in 1934 and 1945 have been supplemented by un- described larger mollusks from Viti Levu collected by Ladd in 1934 and by micromolluscan material not previ- ously described. Additional material collected in recent years has been furnished by the Geological Survey De- partment in Fiji and by William Briggs of the US. Geological Survey who visited Viti Levu in 1962. T0nga.—A few Tertiary mollusks were collected by J. E. Hoffmeister in 1926 and 1928; post-Tertiary mate- rial was collected by J. Ostergaard in 1926 and was loaned by the Bernice P. Bishop Museum in Honolulu. The largest molluscan collections are those from Eni- wetok, Guam, and Fiji, in that order. The Eniwetok collections from drill holes are rich in well-preserved micromollusks. Those from Guam and Fiji are outcrop samples, and many of them are molds or calcite casts; they are comparatively poor in micromollusks. ACKNOWLEDGMENTS Prior to her retirement in 1952, the late Dr. Julia Gardner made preliminary determinations of many of the fossil mollusks collected by Geological Survey per- sonnel in the Mariana Islands and Palau. Her identifi- cations of Saipan mollusks were published in Professional Paper 280-A (Cloud and others, 1956). In connection with her studies, she assembled a useful index of refer- ences on island fossil mollusks. In 1947 she visited Palau where she collected from the Palau Limestone in the Koror area. In 1945, I discussed Palauan geology with the late Prof. Risaburo Tayama in Sendai, Japan, and was given suggestions as to promising places in which to collect fossil mollusks. These suggestions proved invaluable during fieldwork in Palau in 1958. At that time I was cordially received and was given much assistance by Mr. R. P. Owen, staff entomologist with the Trust Territories in Koror. The extensive collections of Recent mollusks at the I'S. National Museum contain many shells collected by Dr. J. P. E. Morrison and others in the Marshall Islands during Operation Crossroads in 194647 and later. These shells were particularly useful in studying fossils ob- tained from drill holes. The Academy of Natural Sci- ences in Philadelphia, through Dr. R. T. Abbott, curator, loaned Recent chitons for comparative studies and gave full acceSs to the collections when I visited Philadelphia in 1964; the Bishop Museum, through Mr. E. H. Bryan, Jr., curator, loaned the fossil material from Tonga col- lected by Jens Ostergaard; the British Museum (Natural History), the Australian Museum, and the Museum of Comparative Zoology at Harvard loaned samples from the drill holes on Funafuti. Professor René Abrard of the Museum National d’Histoire Naturelle loaned fossil material described by him from the New Hebrides. Dr. C. Beets of Leiden, Netherlands, kindly checked identi- fication of a species that appeared to be closely related to a form described by him from the Miocene of Borneo. Mr. W. M. Briggs, Jr., and Mrs. Evelyn Bourne, both of the US. Geological Survey, aided in the preparation of much of the material, and Mr. Briggs made almost all the photographs of fossils. I am indebted to Drs. H. A. Rehder and J. P. E. Morrison, of the US. National Museum, and Dr. Robert Robertson, of the Academy of Natural Sciences, for assistance in the identification of certain mollusks. The manuscript has benefited from critical reviews by W. P. Woodring of the US. National Museum and by Dr. R. T. Abbott of the Academy of Natural Sciences. GEOLOGY STRATIGRAPHY Detailed studies in recent years have greatly increased our knowledge of the Cenozoic sections in several of the island groups under consideration. In the Pacific Basin proper, a standard section has been established from results of deep drilling in the Marshall Islands (described in the numerous chapters of U.S. Geol. Survey Prof. Paper 260, especially Emery and others, 1954; Cole, 1958; Todd and Low, 1960; Ladd and Schlanger, 1960; Schlanger, 1963). Outside the basin, in the Mariana Islands (Cloud and others, 1956; Doan and others, 1960; Tracey and others, 1964); in Palau, (Mason and others, 1956); and in Fiji, (bulletins published by Geol. Survey Dept. of Fiji, including: Bartholomew, 1959, 1960; Houtz, 1959, 1960, 1963; Ibbotson, 1960, 1962; Rickard, 1963; Houtz and Phillips 1963; also Cole, 1960) ; detailed mapping and paleontological studies have established similar sections. In the Ellice Islands, in the New Hebrides, and in Tonga, available information is much less complete. Each of the seven island groups has a section of Quaternary limestones and all except Funafuti in the Ellice group are known to have a Tertiary sequence as well. The known Tertiary in all groups, except that in the New Hebrides, extends downward into the Eocene. No Paleocene has been reported from any of the island groups. The subdivisions of the Tertiary are based on the sys- tem developed for the East Indies by van der Vlerk and Umbgrove (1927). By using larger Foraminifera, the GEOLOGY TABLE l.—-Distribution of Cenozoic sediments in the island area lX, present; question mark indicates uncertain identification] Marshall Islands Mariana Islands Fiji —-— Tonga Indo— Eniwetok Bikini Ellice Guam Saipan Tinian Palau New Viti Lan nesiaI Hebrides Levu Recent X X X X X X X X X X Quaternary Pleistocene X X X X X X h Pliocene X X X ‘l X X X X X Upper Upper Miocene X X 7 X X X X ' ~ 7 ‘7 Tertlai 3 f Lower X X X X c Miocene X X X X X X (l ()ligocene Lower c X ? X ? X X Tertiary 7 fl 7 — b X X X X X X W Eocene a2 X 1Some workers (Bemmelen, 1949, p. 88) place part of Tertiary g into the Pliocene with Tertiary h. 2 Occurrence of Tertiary a baded on smaller Foraminifera on Sylvania Guyot adjoining Bikini (Hamilton and Rex, 1959). Tertiary sequence was subdivided into six units, desig- nated by the letters a—f. Later, two younger stages 9‘ and h were added (Leopold and van der Vlerk, 1931; table 1, this paper). This classification has proved to be exceedingly useful in the western Pacific island groups. In the atoll groups (Marshall and Ellice Islands), the sedimentary rocks consist of reef limestone and dolomit- ized limestone. Similar limestones occur in the high island groups along with a variety of terrestrial and marine tufts and coarser volcanic sediments. The Cenozoic sedimentary rocks are known to rest on volcanic rocks in most areas. In the Ellice Islands, no volcanic rocks are exposed nor have they been reached by the drill, but seismic evidence suggests such a foundation at a depth of about 1,800 feet (Gaskell and Swallow, 1953, p. 3). In Fiji (McDougall, 1963) and Tonga (Guest, 1959, p. 3), plutonic rocks are known; their presence records more complex histories than in other island groups. The Tongan plutonic rocks are thought to be of pro-Tertiary age. Fossils from the section established by deep drilling in the Marshall Islands have been studied by several workers; their findings have been published as chapters of US. Geological Survey Professional Paper 260. The major divisions recognized are shown in table 2. With slight modification, this is the arrangement given by Cole (1958, p. 745). EOCENE The only known occurrence of lower Eocene (Tertiary . a) sediments in the island area is the phosphatizedl Globigerina ooze described by Hamilton and Rex (1959) from the top of Sylvania Guyot adjacent to Bikini. The ooze contained no mollusks. Limestones of late Eocene age (Tertiary b) are widely known in Eniwetok, the Marianas, Palau, Fiji, and Tonga. Mollusks occur in some of these limestones, but they are rare, and in many places they are poorly pre- served; none from the families here treated has been specifically identified. In Fiji and Tonga the limestones have yielded diagnostic larger Foraminifera, but no other identifiable fossils. In Palau, numerous fragments of an upper Eocene limestone containing larger Foraminifera, algae, and unidentifiable mollusks occur in a volcanic breccia. In the Mariana Islands, upper Eocene rocks have yielded a considerable variety of fossils, including Foraminifera, radiolarians, discoasters, algae—and in TABLE 2,—Major stratigraphic subdivisions recognized in holes drilled in the Marshall Islands Eniwetok Bikini Stratigraphic divisions Depth Depth (feet) (feet) Post-Miocene 0—615 0-700 Upper Miocene Tertiary 9 615—860 700—980 Tertiary f 860—1,080 980—1,166 Lower Miocene Tertiary c 1,080—2,780 1,166—2,556+ Upper Eocene Tertiary b 2,7804,610 8 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS some places fragmentary and poorly preserved mollusks have been found. In the Marshall Islands, some Eocene mollusks have been recovered from deep holes on Eni- wetok. These include poorly preserved bivalves (Area and Pectem, but most are the molds of minute gastro- peds, including turbinids and cyclostrematids, that are not identifiable. OLIGOCENE Limestones containing larger Foraminifera diagnostic of the lower Oligocene of the Indonesian section (Tertiary e) have been found in Fiji and in Guam (Cole 1960, 1963). The beds containing these fossils are restricted in their distribution and to date (1965) have yielded no identifiable mollusks. Some of the limestones on Guam that contained Oligocene larger Foraminifera also yielded an assemblage of smaller Foraminifera that is definitely early Oligocene (Tertiary c) in age (Ruth Todd, oral commun., 1963). The section drilled in the Marshall Islands includes beds containing smaller Foraminifera that may repre- sent the lower Oligocene (Tertiary c) but the corre- lation is questionable (Todd and Low, 1960). In drill holes F—l and E—l on Eniwetok, there is an interval of about 100 feet, (2,687—2,780 ft) that Cole (1958, p. 745, 748) labeled “unknown” because it yielded no diagnostic larger Foraminifera, Above this interval the beds con- tain lower Miocene Foraminifera (Tertiary e) and below they contain upper Eocene species (Tertiary 1)). Along with the smaller Foraminifera that are suggestive of the lower Oligocene, the questionable beds yielded three specimens of Rissoina ailinana Ladd, n. sp., a species that occurs in some Tertiary 6 samples in both Eniwetok and Bikini. Also recovered were nine specimens (from four samples) of a well-preserved Miocene Ampullina, described from East Borneo by Beets (1941) as Globu- laria berauensis.1 Because of the occurrence of these mollusks, I have tentatively assigned the unknown inter- val to the Miocene. No beds that would represent the upper Oligocene (Tertiary d) have been found in any of the island groups here considered. The Fina-sisu Formation of Saipan, previously assigned to the late Oligocene (Todd and others, 1954) on the basis of smaller Foraminifera, is now regarded as early Miocene in age (Ruth Todd, oral commun, 1963). MIOCENE Miocene sedimentary rocks have been recognized in all the island groups except in the Elliee Islands. In the Eniwetok drill holes, shallow-water lagoonal limestones 1M1": Beets kindly. checked the identification of this species by comparing an Emwetok shell With his type in the museum in Leiden. exceed 2,000 feet (table 2). All three major subdivisions of the Miocene (Tertiary e, f, and g) are represented, but the section is not complete, inasmuch as a solution uncon- formity appears at the top of Tertiary e (Schlanger, 1963, p. 995). Miocene reef limestones are also found in Palau. The total section exceeds 750 feet, but some parts may be younger than Miocene (Cole, 1950; Mason and others, 1956,~ p. 55—59). In at least two areas in Palau the Miocene includes thin tuffaceous limestone and marl that are here assigned to the upper Miocene (Tertiary g). On Saipan and Tinian in the Mariana Islands, the lower Miocene (Tertiary e) limestones are 750 to nearly 1,000 feet in maximum thickness and include some tuffaceous facies (Cloud and others, 1956, p. 62—77; Doan and others, 1960, p. 60—62). Tertiary e rocks on Guam exceed 2,000 feet, but most of the sequence consists of volcanic flows and breecias. Although some of the included lime- stones are of shallow-water origin, Globigerina-rich sedi- ments, of deeper water origin, are present. On Guam the Tertiary e rocks are overlain by several hundred feet of younger limestones; some of these are definitely of Ter- tiary f age, others may be Tertiary g. (Tracey and others, 1964). In Fiji the Miocene sequence is dominantly vol- canic. It consists of many thousands of feet of agglomer- ates, tuffs, and marls, some water laid, together with a variety of igneous rocks. Limestones of shallow-water origin are at least 200 feet thick in some areas. Miocene rocks of comparable types have been reported from the less well known New Hebrides (Mawson, 1905; Abrard, 1946). In Tonga the known Miocene is thin; it consists of a series of volcanic tuffs totaling 200—300 feet in thick— ness (Hoffmeistcr, 1932, p. 30, 33). POSTvMIOCENE In the island area it is difficult, if not impossible, to recognize age boundaries in the post-Miocene sediments. Diagnostic larger Foraminifera which are so useful in subdividing the Miocene and older Tertiary beds have not been found. Other organisms, especially planktonic smaller Foraminifera, discoasters, and radiolarians, offer great promise, but these organisms are not everywhere present, and their geologic distribution in the islands has not yet been adequately determined. Mollusks, even where well preserved and abundant, are of limited use- fulness in determining exact post-Miocene ages. In the Marshall Island drill holes, the top of the Miocene has been agreed upon by those who have studied the Foraminifera from cores and cuttings. The post- Miocene section ranges from 510 to 700 feet in thickness, but it has not been subdivided accurately (Cole 1958, p. 745; Todd and Low, 1960, p. 802, 807). These limestone beds thought to be mostly lagoonal, have not yielded PALEONTOLOGY 9 assemblages of discoasters or radiolarians. The smaller Foraminifera in the elevated post-Miocene reef lime- stones of Fiji, Tonga, and Palau, are preserved mostly as unidentifiable molds, as are those in most of the Quater- nary sediments drilled on Funafuti. The post-Tertiary limestone of the‘Mariana Islands contains both larger and smaller Foraminifera, but no extinct species are in- cluded and hence no exact stratigraphic boundaries are indicated. Some of the elevated limestones of the New Hebrides contain molluscan species previously reported from the Pliocene of Java (Abrard and La Riie, 1937). PLIOCENE The Pliocene-Pleistocene boundary is perhaps the most difficult Cenozoic boundary to recognize in the island area. Environmental conditions in the tropical islands seem to have been little affected by the onset of glaciation in other parts of the world, and no clear stratigraphic break appears. In cores of deep-sea sediments containing layers of ice- rafted materials, the earliest of these can be taken as the base of the Pleistocene, and correlations with other deep- sea sections can be made on the basis of wide-ranging Foraminifera or other planktonic organisms. Eventually a system of this sort may be successfully applied to some of the sediments of the island area. PLEISTOCENE AND RECENT In the absence of definitive paleontologic evidence, it is not possible to recognize Pleistocene beds with cer- tainty, though suggestive physiographic evidence has been called upon in several areas. In the Bikini drill holes, three rock units above 294 feet, characterized by distinctive species of still-living smaller Foraminifera, seem to be related to present physiographic features. These rock units are thought to represent three late stages of reef growth, probably separated by two periods of emergence representing Pleistocene shifts in sea level (Emery and others, 1954, p. 2, 75, 132433). On Saipan, the name Mariana was applied to lime- stones now as much as 500 feet above existing sea level and the name Tanapag to limestones below 100 feet. The Mariana includes reef and lagoonal deposits, whereas the Tanapag represents rock of an elevated fringing reef. The Mariana was assigned an early, and the Tanapag a younger, Pleistocene age. These interpretations are sup— ported by a period of faulting that intervened between the benching of the Mariana and the deposition of the Tanapag. Carbon-14 analyses of the Tanapag seem to support the p0stulated younger Pleistocene age (Cloud and others, 1956, p. 2, 79—80, 87). On Guam, the Mariana Limestone yielded no diagnostic larger Foraminifera but was assigned a Pleistocene, or possibly Recent, age (Cole, 1963, 1). E1, E10). In eastern Fiji (Lau), the Fulanga Limestone is com— posed of elevated veneers of reef limestone, occurs on two or three islands, and has been referred tentatively to the Pleistocene. Paleontologically it yielded two pre- viously undescribed echinoids, a new decapod crustacean, and a few species of still-living mollusks. Among the mollusks are species that no longer live in Fiji. The pre- ceding data suggest an appreciable age for the Fulanga, but they do not clearly indicate Pleistocene. That inter- pretation was based almost entirely on field evidence (Ladd and others, 1945, p. 267, 313, 322, 380). CORRELATION Age determinations and correlations involving major stratigraphic units in the several island groups are based on the letter classification established for Indonesia (van der Vlerk and Umbgrove, 1927; Leopold and van der Vlerk, 1931). No attempt is made to tie these Indonesian units to the stages of the standard European sequences. Efforts of this sort have been made, but most such efforts have been regarded as tentative, even by their proposers (Glaessner, 1943, 1959; Todd and others, 1954; Cloud, 1956; Eames and others, 1962). The exact ages (by the Indonesian letter system) of some of the Tertiary units in the islands are in question because of conflicting inter- pretations of faunal evidence, notably that of the larger versus the smaller Foraminifera. These differences are still being discussed vigorously. (Cole and others, 1960; Glaessner, 1960; Eames and others, 1962). The mollusks, which rarely occur in beds with diagnostic Foraminifera, are not deeply involved with questions of exact correla- tion. The correlations shown in table 3 are based more heavily on evidence from the larger Foraminifera than on that of other groups of fossils. It is recognized, how- ever, that eventually the evidence of such mobile plank- tonic groups as some of the smaller Foraminifera, the Radiolaria (Riedel, 1959), and especially the discoasters (Bramlette and Riedel, 1954) may offer modified, and perhaps sounder, correlations. Boundaries and units that are questionable are so marked in table 3, and it should, perhaps, be repeated that the exact ages of all post- ‘ Miocene units in the island area are debatable. PALEONTOLOGY GEOGRAPHIC AND GEOLOGIC DISTRIBUTION OF SPECIES The geographic distribution of all the species treated is shown in table 4. The Marshall Island faunas are the richest, and more than half of the total number of named forms are recorded from Eniwetok alone. Fiji ranks second in number, Palau a poor third. Faunas from the other island groups are smaller but none of these areas, except the Mariana Islands, has been adequately col- lected. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLAN S 10 :3. .IN .15 £52 acamfiw .m .m JEQEEM .2 .m c. 9......89. can : flier; mo :3 35...... 31:53.; sad 2: .._._h imam :H 90391 .0 3.2.: F5051... 33.7 9...... v1.5... ”was... $5.32.... NEE...» RESP: 693v 3.307... m»: i. wwmfi: QNCNGIMwQ KC :CEGNQ....QQI.M Eqmfib 3mm; £3. 95 coo—ESSA :Swa. .Efim 9:50.23 ‘93”. HENZAw :0 952.5qu . .I n. M. .5an3“. . .300 a m fi am:£.un.mm « «£53920 m . mcwuom 9539.... m 00. En. :nEmmI coszEn. n 9.23:... vca mm ww Sum—no.3“. .Eu. nEm>:.m:on. x._9:.< h. .6358 .95. a m NEEEEB :oanSn. , .E... nmcauns. IN ~| m >1>O.. . . o mu.:o.:_n. :o.um:..cn. A v we 0.9.... 39.95932 J 05009.0 n 6. Ma m w c2325“. 9.05ij m. mw..om 039:: cazuonmm... .I mxSmMEM m mo.”MW_.o> wcoummE: 9.33:... m . wcwuo 828E: ummmhfiy 98m. x :2 9....qu . . m H. >m<_.r~_m._. n o B a 9.33:... u. o a cunt... ta... mu_:no_o> mm..mw u>:m unnM...mm W m m N. fin. mm:mm9:>_ 0.0x cozuEBL 2.23:... .M I. W o u m E33 5:? 9539:... m w. w. w 1 a I m9; m =2mm. o a D. a . 233...... . w as. 9539...: 3.9.ng w w mfx a Ecstfiuz wwwm wont»... w m m. c 9.9.0:... . . mth. 32...... accume... 9539:... ... W .a a m. 9.2.55. 9.5.5.2. 0:0.me... P w. m acoumoc... 9.059»... mutmw 9;“... 9.0.55. 95005.0 .061 «9.33“. 9.93:... . _n. 9.2mm «26> 9.33:... mmnmcn... 9.23:... 9.899.... O wwwm 3.2mm. wwmw. >m_....< :39. .333. mucmm www.mm. .cmowm mgmoawu :uncm 3 .I D<._ D>mn_ _.:> 5.4246 252... Z>.Zm m1 . | 3 520: SEW“... 3.2. w m. 100.. 2.5% V a .2“. . mo..._m ._.<...mm.< Euchelus (Herpetopoma) instrictus (Gould) _______________________ (Vaceuchelus) angulatus Pease _______________ X X Turcica (Perrinia) morrisoni Ladd, n. sp _________________________ Fossarina (Minopa) hofimeisleri Ladd, n. sp__,_ __ _ _______________ Trachus (Trachus) muculatus Linnaeus ____________ X (Troohus) hislrio (Reeve) ___________________________ Isanda (Parminolia) apicina (Gould) _____________________________ Pseudostomatella (Pseudoslomatella) maculala (Quoy & Gaimard) ___________________________________ X Synaptocochlca rosacea (Pease) ___________________________________ Liotina (Dentarene) cycloma Tomlin ______________________________ Turbo (Turbo) petholatus Linnaeus _______________ X X (M armarostoma) chrysostomus Linnaeus ________________________________________________ (Marmarostoma) argyrostomus Linnaeus _______ X X Leptothyra maculosa (Pease) ____________________________________ balneam'i Pilsbry __________________________________________ glareosa marshallensis Ladd, n. sp ___________________________ Neritopsis (Neritopsis) radula Linnaeus ___________ X X Nem'ta (A mphinerlta) insculpta Récluz ____________________ X Clithon (Clithon) corona (Linnaeus) _______________ X M erelz’na (M erel’lna) pisinna (Melvill and Standen) _ _______________ Zeln'na (Clbdezebina) metaltilana Ladd, n. sp ______________________ (Allinzeb’ina) abrardi Ladd, n. sp ___________________________ Rissoina (Zebinella) lenuistriata Pease- _ _ - _ _ _ , A - - _ _______________ (Phosinella) clathmta A. Adams ______________ X X balteata Pease ________________________________________ lransenna Watson _____________________________________ (Itissolina) turricula Pease __________________ X ephamz'lla Watson _____________________________________ plicata A. Adams ______________________ X Lophocochlias minutissimus (Pilsbry) ____________________________ Solariorbis tricarinala (Melvill and Standen) ______________________ Cyclostremiscus (Ponocyclus) novemcarinatus (Mel- vill) ________________________________________ X (Ponocyclus) cingulifera (A. Adams) ____________________ X X X XXXX XXXXX X X Total __________________________________ 11 13 Saipan yielded a poorly preserved Thalotia referred to the subgcnus Beraua, which was established by Beets (1941, p. 14) for T. erinaceus from the same Borneo beds. The Saipan shell closely resembles Beets’ type species. The Borneo beds and the lower Miocene of Eniwetok also have in common the Recent species Cyclostremiscus novemcarinatus (Melvill), and an Eniwetok lower Miocene rissoid seems closely related to Beets’ Rissoina A chiton described by Beets as Cryptoplax menkrawitensis has a close relative in the Miocene of Fiji. The neritid described by Martin from the lower Miocene of Java as Neritina jogjacartensis is a Smaragdla that occurs throughout the Miocene under Eniwetok and in the upper Miocene of Palau. Another of Martin’s indrai. lower Miocene Java species, Tectus bomasensis, may be identical with a species from the Miocene of Fiji. Several still-living species are common to the upper Tertiary of the island area and Indonesia. SYSTEMATIC PALEONTOLOGY The systematic order followed is, in general, that used in “Indo-Pacific Mollusca” under the editorship of R. T. Abbott (1959); this arrangement, in turn, is based on Thiele (1929—31) and Wenz (1938-44). An exception is made for the chitons. They are considered before the gastropods rather than after them, and the systematic order given in the “Treatise on Invertebrate Paleontol- ogy” is followed (Smith, 1960). Drill-hole specimens taken from cores are so identified; all other drill-hole specimens were picked from cuttings. PALEONTOLOGY Depths of many cuttings samples have been rounded to the nearest foot. The following new subgenera are proposed: Vitiastraea, subgenus of Astraea, Turbinidae. Type: Tectarius rehderi Ladd, n. sp. Suva Formation, lower Miocene (Tertiary fl, Fiji, page 45. Gender feminine. Subditotcctarius, subgenus of Tectarius, Littorinidae. Type: Tectm‘ius rehderf Ladd, n. sp. lower Miocene (Tertiary f), Bikini, Marshall Islands, page 59. Gender liiasculine. Ailinzebina, subgenus of Zebina, Rissoidae. Type: Zebina abrardi Ladd, 11. sp. Recent, Bikini, Marshall Islands, Gender feminine. One-third of the 75 new species and subspecies de— scribed are represented by only 1 or 2 specimens. Of these 25 poorly represented forms, 2 are from Palau, 2 from Fiji, and the balance from drill holes in the Marshall Islands. Future collecting in Palau and Fiji may yield additional specimens of rare species, but there is little prospect of additional drilling in the Marshall Islands. The rare Marshall Island species can be looked for, how- ever, when reef drilling is undertaken in Hawaii or another part of Polynesia. page 65. CHITONS Most chitons are rock clingers and are found most abundantly on rocky shores. They are not limited to such shores, however; even along beach coasts they may find some sort of hard surface—such as the shell of a dead oyster—-to which they may adhere. As a group, the chitons of the existing seas are par- ticularly abundant in the Australian region where some 200 species have been identified. In that area also, fossil forms have been described from upper Tertiary and Pleistocene beds. Many reef—encircled islands in the Pacific offer favor— able niches for chitons. Chitons may be particularly abundant in the nips that are developed at high—tide level along most limestone coasts,>an(l they may also be found on blocks of reef rock on reef flats. (Joral itself is not a choice base because most chitons feed on vegetation. Hull (1925, p. l2l, in working on the Great Barrier Reef, found that only carnivorous species of Cryptoplax, Schz'zochiton, and some species of Acanthochitona are to be expected on living coral. Some of these chitons are specializerl forms adapted to living in holes or crevices in coral. Only a single specimen of one of the three genera mentioned by Hull was collected from the Recent fauna in the Marshall Islands during the investigations of 1945—46 (a Cryptoplaa: found between tide levels on 21 Eniwetok), but representatives of all three genera were recovered from the Tertiary sections drilled in the Mar- shall Islands. In addition, a CryptOplax was collected from the Miocene reef and reef—flat deposits in Fiji and Palau; the Palau deposits also yielded Schizochiton. No fossil chitons were obtained in the Mariana or the New Hebrides Islands, and only a single undetermined valve has come from Tonga. The Marshall Island drill holes and the marly upper Tertiary deposits of Palau and Fiji yielded the most specimens. In addition to the de- scribed material, a total of 26 undetermined specimens were obtained in the island area. Order NEOLORICATA Family SCHIZOCHITONIDAE Genus SCHIZOCHITON Gray Gray, 1847, Zool. Soc. London Proc., p. 65, 68, 169. Type (by monotypy): Chiton incisus Philippines, Torres Straits, northeast Australia. Schizochiton includes elongate chitons characterized by a deep fissure in the tail valve and by the develop- ment of lines .of prominent ocelli on all valves. On reefs they live in protected spots, under blocks, or in crevices in dead coral. Sowerby. Schizochiton incisus goikulensis Ladd, n. subsp. Plate 1, figures 1—3 Tail valve large, thick; dorsal ridge flattened, lateral pleural areas gently concave, lateral posterior areas tri- costate; entire surface covered by strong slightly flat- tened ribs that are distinctly narrower than the flattened areas between; ribs tend to parallel anterior margin of lateral pleural areas but follow a zigzag course, best developed on the left side; 22 ribs on right side, 21 on left. Lateral-posterior areas less strongly ribbed than lateral pleural areas, those of the left side more irregu- larly angled than those on the right; 15 ribs are dis- tinguishable on right side, 19 on left; large eyepits present where ribs meet diagonal costae of lateral-pleural areas. Deeply excavated caudal sinus with pustulose surface leads to prominent mucro; on‘sides of sinus the pustules are roughly alined in rows. Interior of valve smooth near center, irregularly ridged at sides; sinus broadly V-shaped with low rounded projections into apex of V; sutural plates broad and regular; posterior insertion plates cut by three prominent slits on each side; teeth stout, distinctly crenulated outside. Measurements of valve (holotype), USNM 648208: length 10.0 mm, width 9.6 mm, convexity 4.5 mm. The above description is based on a single well-pre— served specimen. It has been compared with specimens of the Recent S. incisus Sowerby (Sowerby, 1841, p. 61; 22 Pilsbry, 1892, p. 235—236, pl. 51, figs. 1—8) from the nearby Philippines and Schouten Islands. The fossil is larger and has a greater number of ribs and an unusually well developed pustulose surface in the caudal sinus. Occurrence: Marl facies at base of the Miocene (Ter- tiary g) Palau Limestone (USGS 21301), near village of Goikul, Babelthuap, Palau. Schizochiton marshallensis Ladd, n. sp. Plate 1, figures 4—9 Head valvo with six prominent lines of close-set ocelli; each of two outermost rows having about 20 pits each, the inner four rows with about 30 each; surface between rows marked by close-set zigzag ridges separated by grooves of about the same width. In the single worn specimen, the ridges form a series of chevrons between each two rOWs of ocelli, the angle formed by the ridges, pointing forward. Intermediate Valves beaked, lateral areas narrow and slightly elevated, separated from centralarea by a strong diagonal bearing a dozen or more ocelli; surface of entire valve crossed by flattened more or less zigzag ridges that on most specimens are much narrower than the spaces separating them; dorsal ridge broadly rounded having flattened longitudinal ridges that meet with the ridges of the central area to enclose irregular and diamond- shaped depressions. On valves believed to represent sec- ond valves, the flattened ridges of the central area extend only one—third to one-half way to the main dorsal ridge before meeting a series of longitudinal ridges to form a diamondback pattern; insertion plates with single slit. Tail valve large, thick; dorsal ridge rounded; lateral pleural areas concave; lateral posterior areas with 4 prominent oeelli—bearing costae on the right side and 4 or 5 on left; insertion plates with 4 prominent slits on each side; sculpture similar to that of other valves; flat- tened ribs on lateral pleural areas range from 14 to 20; surface of caudal sinus rough with traces of chevron- shaped ridge pattern pointing toward mucro. \Ieasurements of the types tin mm) : Length Width Con verity Holotype (a tail valve, E-l, Eniwetok, 870—880 ft), USNM 648209 ______ 8.2 7.8 4.6 Paratype A (a head valve, F-l, Eniwetok, 740—750 ft), USNM 648210 ______ 5.5 5.7 3.0 Paratype B (a second valve, F—l, Eniwetok. 750—760 ft), USNM 648211 ______ 7.2 6.4 3.9 Paratype C (a second valve, 2A, Bikini, l,030—l,034 ft) USNM 648212 ___- 13.4 — — CHITONS AND GASTROPODS FROM \VESTERN PACIFIC ISLANDS Measi'remenls of the types (in mum—Continued Length Width Converity Paratype D (an intermediate valve, E-l, Eniwetok, 830—840 ft), USNM 648213 ______ 4.1 4.0 1.4 Paratype E (an intermediate valve, 2A, Bikini, 893—899 ft). USNM 648214 ______ 13.3 — — 1 Incomplete. S. marshallensis differs from the Recent S. incisus Sowerby and the new subspecies S. incisus goikulensis by having four or five posterior ridges on each side of the posterior valve. S. incisus goilculensis does not showethe chevron-shaped ridge pattern in the caudal sinus ex- hibited by S. marshallensis and by some specimens of S. I'ncisus. The Recent S. polyps Iredale and Hull has a jugum that is smooth or nearly so. Occurrence: Nineteen separate valves, believed to represent a single species, were recovered from cuttings from the three deep holes on Eniwetok and one of the deep holes on Bikini. The youngest specimen, from a depth of 660—670 feet, is in beds assigned to Tertiary g, and the oldest, from a depth of 2,610—2,620 feet, is in beds referred to Tertiary e. The valves are rare, and Only twice were two specimens found in a single sample. The stout tail valves show the most diagnostic features,.and a total ‘bf seven such valves were recovered; one of these, from a depth of 870—880 feet in drill hole E—1 on Eniwe- tok, is the holotype. Only one head valve was found, paratype A. depth 740—750 feet in hole F—l on Eni- wetok. The remaining 11 specimens are intermediate valves, 3 being No. 2 valves showing the jugum. Genus LORICELLA Pilsbry Pilsbry. 1892, Manual Conehology. v. 14, p. 288. Type (by monotypyl: Lorica angasi H. Adams (in Adams, H., and Angas, G. F., 1864, Zool. Soc. London Proc, p. 193). Recent, Australia. Loricella sp. A Plate 1, figures 10—12 Head valve broadly arched, nearly twice as wide as long; insertion plate narrow, pectinate, cut by 10 slits. Upper surface of valve smooth near median apex; re- mainder of surface with 13 radial rows of beads; the beads elongated parallel to anterior margin of valve; beads in row next to posterior margin on each side rise from a moderately strong rib. Measurements of the fig- ured head valve (F—l, 55—60 ft), USNM 648215: length 1.6 mm, width 2.8 mm, convexity 1.1 mm. Intermediate valve highly arched and slightly beaked; jugum smooth; remainder of valve crossed by 14 ribs on PALEON TOLOGY each side, the 3 ribs nearest the jugum being smaller than the others; lateralareas each with 4 diagonal ribs, the anterior and posterior ones larger than the others and bearing obscure ocelli on the beads formed by the cross- ing of the vertical ribs. On the single fossil available, the insertion plates are not preserved. Measurements of the figured intermediate valve (E—l, 35~40 ft), USNM 648216: length (minus insertion platesl 2.0 111111, width 3.6 mm, convexity 1.5 mm. The fossils do not appear to be closely related to de- scribed species, but they may be immature and a specific name is withheld. The species may be still living in the Marshall Islands, though no specimens have yet been collected. The genus is widely known from the Australia— lndonesia area but appears not to have been previously reported from the islands of the 0an Pacific. Occurrence: One head valve and one intermediate valve . from drill hole E—l on Eniwetok Atoll at depth of 35—40 feet and one head valve from F—l at depth of 55-60 feet; age, Recent. Family CHITONIDAE Genus LUCILINA Dall Dal], 1882, US. Natl. Mus. Proc., 4, p. 284, 287, (2 Lucia Gould, 1862, Boston Soc. Nat. History Proc., v. 8, p. 283; [not] Swainson, 1833). Type (by monotypy): ('hfton confossus Gould. Re— cent, Fiji. Lucilina russelli Ladd, n. sp. Plate 1, figures 13-15 Tail valve small, moderately arched, thick; mucro prominent, lying directly above the posterior edge of the valve; profile below and above mucro gently convex; sinus wide, its flat bottom pectinated; anterior insertion plates broadly rounded, their outer edges pectinated above; posterior insertion plates short, thick, inclined forward, strongly grooved outside and cut by numerous (about 16) slits. In front of a broad ridge extending from the mucro to the anterior corners, the surface bears numerous slightly curved vertical riblets; surface pos- terior to ridge microscopically punctate with scattered larger pits that represent ocelli; obscure elevated hori- zontal lines cross the post mucral area. Measurements of the holotype (only specimen), ['SNM 648217: length 4.1 mm, width 6.2 mm, convexity 2.7 mm. The Eniwetok fossil is very closely related to the Recent L. confessus (Gould) (USNM 30763), but the Recent shell does not show the vertical riblets on the anterior part of the valve that are so well developed on the fossil; the Recent shell likewise has a stronger ridge from mucro to the anterior corners. 23 Occurrence: Drill hole Kl—B on Eniwetok Atoll at a depth of 537—548 feet; age, probably Pliocene. Lucilina sp. A Plate 1, figure 16 Tail valve small, gently arched, moderately thick; muero about one-third the length from the posterior margin; area behind broadly convex, surface in front nearly flat; bottom of sinus pectinated; posterior inser- tion plates short, inclined forward, strongly grooved outside, and cut by numerous slits. A narrow and promi- nent ridge extends from the mucro to the anterior corners; ahead of the ridge the jugum is smooth, but the remainder of the central area bears an irregular series of pitted grooves that are best developed near the anterior margin; low elevated lines crOss the entire central area parallel to the anterior margin of the valve. Posterior to the mucro the surface is smooth except for scattered ocelli and obscure elevated lines that parallel the pos- terior margin. Measurements of the figured specimen, USNM 648219: a length (insertion plates missingl 2.1 mm, width 3.9 mm, convexity 1.2 mm. This species superficially resembles L. confossus (Gouldl, but its well-developed pitted grooves are not found on the Recent shell. Lucilina sp. A differs from L. rusxelli in having more widely spaced vertical grooves and a more prominent ridge from mucro to the anterior corners. The single specimen is incomplete, and a spe- cific name is withheld. ()ceurrence: Marl facies at base of the Palau Lime- stone (USGS 21304), near village of Goikul, Babelthuap, Palau; age, late Miocene (Tertiary g). Lucilina sp. B Plate 1, figure 17 Tail valve medium in size, moderately arched, thick; mucro prominent, situated almost directly above posterior margin; surface below mucro slightly concave; sinus broad, flat—bottomed, and pectinate; anterior insertion plates wide and flat; insertion plates along the posterior and lateral margins thick, strongly grooved externally, and cut by numerous shallow slits. Surface of valve eroded but showing traces of close-set riblets that diverge from a broad ridge that extends from the mucro to the anterior corners of the valve. Measurements of the figured specimen (Fiji sta. 110B), USNM 648218: length 6.5 mm, width 10.3 mm, con- vexity 4.0 mm. On a poorly preserved intermediate valve from the same locality, a low, narrow ridge separates the pleural areas from the central area; traces of fine vertical riblets are preserved on the jugum and a fanlike pattern of 24 similar lines is discernible on the rest of the central area. The valve measures 19.2 11111] in width. The illustrated Fijian fossil resembles the Recent L. confess-us described by Gould from Fiji but has a lower mucro and the vertical riblets of the central area that are well developed on the fossil are not present on the Recent shell. Occurrence: In the Ndalithoni Limestone; age, prob- ably Pliocene (Tertiary h); Vanua Mbalavu, Fiji (sta. 110B). Two similar but more coarsely ribbed tail valves from the Miocene Suva Formation; age, Tertiary f; Viti Levu, Fiji (sta. FB20), and from drill hole F—1 on Eni- wetok at a depth of 320—330 feet (Tertiary h or Pleisto- cene) are questionably referred to this species. Lucilina sp. Plate 1, figures 18, 19 Intermediate valve minute, width greatly exceeding length, moderately arched; beak and dorsal area smoothly rounded; lateral areas divided on each side by a nodose ridge extending from near the beak to about the mid— point of the lateral margin of valve; on posterior side of ridge there is a prominent row of eye spots (eight on each side in figured specimen); lateral area crossed by rounded longitudinal ridges that are better developed on anterior side of diagonal eye-bearing ridge. Insertion plates short, peetinated, each with a single slit at side; insertion plates separated by a shallow dentieulated sinus. lVIeasurements of the figured specimen (MCZ 28020): length 0.9 mm, width 3.0 mm, convexity 0.6 mm. Represented by two intermediate valves, both obtained from the same small sample. The specimens may be immature. They seem similar in general features to L. picta (Reeve), a Recent species from the Torres Straits, but I have not seen specimens. Occurrence: Cuttings from a drill hole on Funafuti Atoll at depth of 70 feet; age, Recent. Family ACANTHOCHITONIDAE Genus ACANTHOCHITONA Gray Gray, 1821, Nat. Arrangement Mollusca, London Med. Reposi- tory, v. 15, p. 234. Type (by monotypy): Chiton fascicularis Linnaeus. Recent, Mediterranean. Acanthochitona sp. Plate 1, figures 20, 21 Intermediate valve thin, highly arched; exposed part of valve semicircular in outline, lateral areas densely pustulose, the pustules in indistinct radial lines; dorsal area narrowly triangular with traces of longitudinal CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS grooves; beak inconspicuous; insertion plates wide, each with a single slit near posterior edge. Measurements of the figured specimen (E—1, Eniwetok, 770—780 ft), USNM 648220: length 1.1 mm, width 2.5 mm, convexity 0.8 mm. Occurrence: Two slightly worn specimens from drill hole E—l on Eniwetok Atoll, depth 560—780 feet; a simi- lar intermediate valve was recovered from drill hole 2B on Bikini at depth of 873—884 feet; the figured specimen and the Bikini specimen are from beds referred to late Miocene (Tertiary g). The younger Eniwetok specimen (560—570 ft) may be Pliocene. Genus CRYPTOPLAX Blainville Blainville, 1818, Dietionnaire Sci. Nat., v. 12, p. 124. Type (by subsequent designation, Herrmannsen 1852, Indicis Generum Malacozoorum Primordia, supp., Cas- sellis, p. 391: Chiton larvae-forum's Burrow, Recent, southwest Pacific islands. A group of vermiform chitons with well-developed fleshy girdles; adapted to living in burrows and other holes in coral or other rock. J. P. E. Morrison collected numerous specimens beneath pieces of coral rubble on the barrier reef off Noumea in New Caledonia. He noted that the chitons were completely light fugitive (J. P. E. Morrison, oral common, 1961). Insertion plates are ex- tended forward; head valve with three slits; others unslit. Though specialized, species in the same advanced state have been described from the Tertiary of Australia and Indonesia, and the occurrence of representatives in the Miocene of the Marshall Islands and Fiji is not unex- pected. Cryptoplax cf. C. menkrawitensis Beets Plate 1, figure 22 Three incomplete intermediate valves and a tail valve from the Miocene (Tertiary f ) Suva Formation of station 160, Viti Levu, Fiji, bear the pustulose sculpture of C. menkrawz’tensis Beets (1941, p. 8—9, pl. 1, 1—3; 1942, p. 242, pl. 26, 4—6) from the upper Miocene of East Borneo. Measurements of the figured Fijian specimen, an inter- mediate valve, USNM 648221: length (incomplete) 1.7 mm. The tail valve from Fiji is proportionately longer and more highly arched longitudinally than that of Crypto- plax sp. A from Bikini (below); in the Fijian specimen the continuous insertion plate is extended slightly for- ward. Cryptoplax sp. A Plate 1, figures 23—27 Head valve small, slightly longer than wide, central areas more than a semicircle; apex small; insertion plate PALEONTOLOGY broad, bearing three grooves that end in shallow slits or notches; surface covered by close-set pustules arranged in rows paralleling lateral margins; shallow groove parallels anterior and lateral margins. Measurements of the figured specimen (pl. 1, figs. 23, . 24; E—l, Eniwetok, 750—760 ftl, USNM 648222: length 1.4 mm, width 1.2 mm. Intermediate valves known only from one specimen that is unbroken but shoWs no trace of surface sculpture. Measurements (pl. 1, fig. 25; 28, Bikini, 1,891—1,902 ft), USNM 648223: length 2.1 mm, width 1.2 mm. Tail valve small, slightly longer than wide, mucro rounded, central area wide, bordered on each side by three rows of heavy pustules; insertion plate thick, ex- tending posteriorly beyond the mucro. Measurements of the figured specimen (pl. 1, figs. 26, 27; 213, Bikini, 1,870— 1,881 ftl, USNM 648224: length 1.1 mm, width 0.9 mm, convexity 0.4 mm. Theseulpture of the Bikini tail valve is similar to that of the Recent (7. striatus Lamarck, but in the Recent species the central area is narrower, and the insertion plate is directed forward. The Marshall Island speci- mens probably represent an undescribed species. Occurrence: Head valve from drill hole E—l, Eniwetok Atoll, depth 750—760 feet; late Miocene (Tertiary 9). Intermediate and tail valves from drill hole 2B, Bikini Atoll, at depths of 1,891 1/3—1902, 1,870 1/3, and 1,881 feet respectively; in beds referred to early Miocene (Tertiary e). Cryptoplax sp. B Plate 1, figures 28—30 Two valves of a larger species of ('ryptoplax were re- covered from cuttings in drill hole F—l, Eniwetok Atoll: a tail valve from a depth of 720—730 feet and an inter- mediate valve from a depth of 800—810 feet, both occur— rences in beds referred to Tertiary 9. Save for the median ridge, all traces of sculpture have been eroded from the valves. A specific determination is not possible, but both valves probably represent, the same species. The general shape and proportions: of the intermediate valve 1 USNM 648225; length 7.3 mm, width 3.0 mm, convexity 1.3 mm] are similar to (‘1. Iacnlcrau'itcnsis Beets from the upper Miocene of Borneo. Measurements of the tail valve, l'SNM 648226: length 3.5 mm, width 3.1 mm, convexity 1.6 mm. The tail valve of ('. sp. B differs from ('. sp. A in hav- ing the insertion plate projecting forward. A small and badly worn tail valve from drill hole E~1 at a depth of 890—900 feet (Tertiary 6) may represent C sp. B; a small . incomplete head valve from this same horizon is pro- 25 portionately wider than C. sp. A and may represent C. sp. B. Cryptoplax sp. Four badly worn intermediate valves and one tail valve occurring with (7. cf. menkrawitensis in the Suva Formation at station 160 (early Miocene, Tertiary f) on Viti Levu may represent a distinct species. All the valves except one are much longer than wide, and all are marked by strong longitudinal ribs rather than lines of pustules. GASTROPODS Family HALIOTIDAE Genus HALIOTIS Linnaeus Linnaeus, 1758, Systema naturae, 10th ed., p. 779. Type (by subsequent designation, Montfort, 1810, Conchyliologie systématique, v. 2, p. 119): Halioti's asinina Linnaeus. Recent, Indo—Pacific seas. H alien's is widely distributed in the warm and tem- perate seas of the world today. Species are particularly numerous in the Australian area but are not uncommon in Japan and others areas in the western Pacific and along the west coast of North America. Some species also occur on reefs encircling the islands of the open Pacific. Cretaceous species have been reported from California (Anderson, 1958, p. 1461 and Puerto Rico (N. F. Sohl, oral commun, 1964). Miocene forms have been described from Australia, Japan, Fijil‘h, and the west coast of North America and Europe. Most species cling to rocks in shallow waters; fossil occurrences are rare. A total of nine specimens are found in the present collections—six from Guam, two from Fiji, and one from Tinian. All, unfortunately, are preserved as internal molds but appear to be identical with, or closely related to, species known to inhabit reefs in these same areas today. All, with the possible exception of the Fijian occurrences, appear to be post-Miocene in age. Subgenus PADOLLUS Montfort Montfort, 1810, Conchyliologie systématique, v. 2, p. 115. Type (by original designatiom: Padollus rubicundus Montfort,, Recent, lndo—Pacific seas. Haliotis (Padollus) ovina Gmelin Plate 2, figures 1, 2 Haliolis ooiua Gmelin, 1791, System naturae 13, p. 3681. Pilsbry, 1890, Manual Conchology, v. 12, p. 124, pl. 19, figs. 7, 8. Ovinotis om'na (Gmelin), Cotton, 1943, Royal Soc. South Aus— tralia Trans, v. 67, no. 2, p. 179. Cotton, 1952, Royal Soc. South Australia. Malacological Sect, no. 1, fig. 20. 26 A medium-sized, elongate-oval, moderately convex species marked by strong radial folds that are clearly reflected on internal molds of the shell. The folds extend more than half way across the last whorl, ending in prominent knobs. A flattened area separates the knobs from a series of elevated perforations that rise from a low keel; below the line of perforations a concave strip extends to a sharp peripheral keel that is marked by spiral threads; columellar plate wide and flat. Measurements of the figured specimen (Guam, USGS 20489), USNM 648227: length 58.2 mm, width 37.5 mm, height 18 mm. Represented in the collections by four internal molds, two of which are immature. Occurrence: Guam, USGS 20489, 20687, 20619, 20602. Age, Mariana Limestone in Reef faeies, Detrital faeies, and Agana argillaeeous member; Pliocene and Pleisto- cene. Recent shells have been reported from Australia and many islands in the western Pacific (Philippines, Ryukyu, Fiji, Ellice, Marshalls, Samoa, and others). Haliotis (Padollus) cf. H. clathrata Reeve Plate 2, figures 3—5 Three internal molds, two from Guam and one from Tinian, may represent this Recent species described from the Philippines (Reeve, 1846a, p. 57; 1846b, pl. 17, fig. 71) and also known from the Marshall Islands. The following notes are based on the fossils. A small elongate—oval species with body whorl flat- tened and spire low. The surface of the body whorl is marked by prominent radial folds that are crossed by numerous waved spiral ribs; the folds terminate at a low-angled carina bearing the molds of large elevated perforations. strong spiral ribs; the peripheral carina is moderately Below the perforated carina there are rounded. The columnar plate is wide and flat. Measurements of the figured specimen from Guam (USGS 20994l, USNM 648228: length 24.8 mm, Width 22.2 mm, height 6.6 mm; figured specimen from Tinian (USNM 6482291: length 15.9 mm, width 8.9 111111, height about 5 mm. Localities: Guam, USGS 20994 and 20639 (immature specimen); Tinian, USGS 21611. Collected by Josiah Bridge. Horizon: Guam occurrences from detrital facies of and Pleistocene (Miocene, Mariana Limestone; age, Pliocene (figured speeimenl and Alifan Limestone, Tertiary g or h); Tinian specimen from limestone ter- race at altitude of 120 feet, probably equivalent to Mariana Limestone of Guam. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Haliotis s. l. Haliotis tuvuthaensis Ladd Haliotis tuvuthaensis Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 351, pl. 50, figs. E, F. The single internal mold on which this species is based does not show the radial folds that characterize H. ovina Gmelin but there are two rows of secondary nodes inside the keel that bears the nodular openings. Occurrence: Island of Tuvutha in Lau (eastern Fiji) at an altitude of 650 feet. Collected by E. C. Andrews. Probably Futuna Limestone, early Miocene (Tertiary f). Haliotis sp. Haliolis sp. Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 351. A single incomplete internal mold resembling H. ovina Gmelin but with a higher spire and a more convex body whorl. Occurrence: Island of Ngillangilla off coast of Vanua Mbalavu in Lau (eastern Fiji) at an altitude of 10 feet. Collected by E. C. Andrews. Possibly Futuna Limestone, early Miocene (Tertiary f). Family SCISSURELLIDAE Genus SCISSURELLA d’Orbigny d’Orbigny, 1824, See. Hist. Nat. Paris Mem., 1, 'p. 341. Subgenus SCISSURELLA 5.5. Type (by subsequent designation, Gray, 1847, Z001. Soc. London Proc., pt. 15, p. 146): Scissurella laevigata d’Orbigny. Recent, Mediterranean Sea. Scissurella (Scissurella) declinans Watson Plate 2, figure 6 Scissurella declinans Watson, 1886, Challenger Rept., Gastropoda, p. 115, pl. 8, fig. 2. Pilsbry. 1890. Manual Conehology V. 12. p. 57. pl. 65, figs. 6-8. Minute, depressed, thin, transparent; upper half of whorl with a strong carina with elevated edges; above the carina the surface of the whorl is flattened, below the carina it is at first concave, then broadly convex; last whorl very large; carina the site of a narrow deep slit extending backward from the aperture; umbilieus wide and deep, funnel shaped, marked by fine lines parallel to inner lip and bordered by a distinct carina; aperture 'ovate, oblique. Sculpture of last whorl consisting of fine spiral striae and lines of growth; on earlier whorls, stronger oblique axial riblets are present both above and below the carina. Measurement of the figured specimen, USNM 648230: diameter 1.3 111111, height 0.7 mm. Occurrence: In drill hole E—1 on Eniwetok Atoll at depth of 3045 feet, a single well-preserved Recent shell; PALEONTOLOGY in hole 215 on Bikini Atoll at depth of 884—894 feet (figured specimenl; late Miocene (Tertiary 9). Recent examples were recovered from drift on Rongelap and Rongerik in the Marshalls and on Ifaluk Atoll; in the Carolines, D. P. Abbott collected the species alive from algae growing on dead coral of patch reefs on lagoon shelf 75 feet from shore in very shallow water (0—4 ft). The type material was collected by the Challenger near Cape York Peninsula, northeast Australia, in coral sand at a depth of 155 fathoms. Scissurella (Scissurella) coronata Watson Plate 2. figures 7. 8 Scissurella coronala Watson, 1886, Challenger Rept., Gastropoda, p. 114, pl. 8, fig. 4. Pilsbry, 1890, Manual Conchology, v. 12, p. 56, pl. 65, figs. 11—13. Very small; spire flattened, thin; upper part of whorl flat, bordered by a strong carina with erect margins; below carina the whorl is slightly concave, then broadly convex; umbilicus moderately wide and deep; aperture large, ovate, oblique. Sculpture consisting of strong, curved axial ribs that are prominently developed on the flat area above the carina and on the convex area below, dying out near the umbilicus; fine spiral threads are present above and below carina. Measurements of the figured specimen (E—l, Eniwetok, 30—35 ft), USNM 648329: diameter 1.9 mm, height 1.3 mm. On the three Tongan fossil specimens the spiral sculp- ture is obscurely preserved, but they seem clearly to represent this strongly ribbed Recent species. Occurrence: Drill hole E—l, Eniwetok, 30—35 feet; age, Recent. Station 3, sea cliff at Houma, Tongatabu, Tonga 1B. P. Bishop Mus, geology No. 1338); from material filling specimens of Turbo argyrostomus. Collected by J. M. Ostcrgaard at an altitude of 35 feet; age, probably Pleistocene. Type material collected in the harbor of Tahiti, Society Islands, near the reefs at a depth of 20 fathoms. Subgenus ANATOMA Woodward \\"oodward. 1859, Zool. Soc. London Proc., p. 204. Type Iby original designation): Seissurella crispata Fleming. Recent, North Sea. Scissurella (Anatoma) equatoria Hedley Plate 2, figures 9, 10 Scissurella equatoria Hedley, 1899, Australian Mus. Mem. 3, pt. 9, p. 551. The following description is based on the fossil mate- rial: 27 Minute; spire moderately high, thin; periphery of whorls located near midpoint and bears a strong carina leading to a slit whose edges are slightly reflected out- ward; above, carina whorls are gently convex; immedi- ately below carina is a concave zone below which the remainder of the base is tumid; aperture subquadrate, oblique; inner lip slightly reflected below; umbilicus nar- row, partly shielded by inner lip. Sculpture consisting of minute close-set curved lines of growth that are more distinct above the carina than below it; spiral threads obscure. Measurements of the figured specimen, MCZ 28021: diameter 0.8 mm, height 0.6 mm. Occurrence: Two specimens in cuttings from a drill hole on Funafuti Atoll, at a depth of 65 feet; nine specimens from drill hole E—l, Eniwetok Atoll, at depths of 20-40 feet; occurrences at both places probably Recent. The single type described by Hedley was dredged from a depth of 200 fathoms off Funafuti. Hedley recognized that S. equatoria is closely related to S. aedonia Watson, a Recent species obtained by the Challenger near Tristan da Cunha in the South Atlantic at depths of 100—150 fathoms. Hedley noted that S. equatoria was the largest species of the genus (major diameter 3.0 mm) and that it also differed from S. aedonia in having a contracted zone beneath the carina and a lesser development of spiral sculpture. Some of the fossil specimens appear to be adults; they are much smaller than the type, but the fossils show the other diagnostic features mentioned by Hedley. Family FISSURELLIDAE Genus EMARGINULA Lamarck Lamarck. 1801. Systémc dcs Animuux sans Vertebrcs, p. 69. Subgenus EMARGINULA s.s. Type (by monotypy): Emarglnula conlca Lamarck (=Patella fissura Linnaeus). Recent, European seas. Emarginula (Emarginula) bicancellata Montrouzier Plate 2, figures 11, 12 E'mm-ginula bicancellata Montrouzier, 1860, Jour. conchyliologie, v. 8, p. 112, pl. 2, fig. 9. Pilsbry, 1890, Manual Conchology, v. 12, p. 256, pl. 64, fig. 42. Small, solid, oval, highly convex; apex narrow, fairly sharp, back slope below apex flattened. Slit narrow, open for about one-third its length; closed section crossed at fairly regular intervals by erect lamellae. Sculpture con- sisting of about 30 radial ribs, alternately larger and smaller, that are crossed by less prominent concentric ribs to give the shell a latticed appearance. 28 Measurements of the figured specimen (British Mus. 1964, 23): length (incomplete) 3.0 mm, width 2.3 mm, height 2.5 mm. Occurrence: A single specimen from the first boring on ' Funafuti Atoll in the Ellice Islands, depth 65—74 feet; tw0 other specimens from drill holes F—l and E—l, Eni- wetok Atoll, at depths of 55—100 feet; all occurrences probably Recent. Originally described from New Cale- donia; also collected in Samoa where it was found under coral blocks and in pieces of dead coral at intertidal levels. Emarginula (Emarginula) cf. E. peasei (Thiele) Plate 2, figures 13, 14 Small, elongate-oval, depressed; side margins slightly arched so that shell rests on extremities; apex incon- spicuous, located about one-third of the length from the posterior end; slit narrow, less than one—fourth of total length of shell. Sculpture consisting of about 21 strong radial ribs which on the posterior half of the shell alter- nate with secondary ribs, the total number of ribs being about 31; ribs crossed at fairly regular intervals by con- centric lirae that form deep pits between ribs. Measurements of the figured specimen, USNM 648231: length 3.3 mm, width 2.0 mm, convexity 0.6 mm. The fessil appears to be most closely related to E. peasei, a Recent species originally described from the Pacific islands (Thiele, 1915, p. 87). The single fossil shell is less than half the size of that of the living species and may be immature. Immaturity may explain the absence on the fossil of the finest sculpture exhibited on the primary ribs and in the pits of the living species. The secondary ribs of the fossil have not been noted on the living shell. Occurrence: In drill hole E—l on Eniwetok Atoll at a depth of 90—110 feet; age, Recent. Emarginula (Emarginula) aff. E. clypeus A. Adams Plate 2, figures 15, 16 Small, broadly oval, narrowed anteriorly, depressed; apex posterior, slightly more than two-thirds of the total length of the shell; anterior slope gently convex, posterior slope flat; shell margin crenulated, moderately arched below; slit narrow, open for one-fifth of its length. Sculpture consisting of about 33 radial ribs, of which about 6—3 on each side——are larger than the others; shell surface latticed by regularly spaced concentric lirae. Measurements of the figured specimen (\F—l, Eniwetok, 60—70 ft), USNM 648232; length 4.3 mm, width 2.9 mm, convexity 1.1 mm. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS pines. Pilsbry (1890, p. 265, pl. 28, fig. 7) noted that the species “has some prominent ribs.” The fossils are smaller than the examples figured by Thiele (1915, p. 97, pl. 11, figs. 24, 25). I have not seen specimens of E. clypeus. The fossils probably represent a distinct species; they may be immature. Occurrence: Nine specimens from drill holes on Eni- wetok Atoll down to depths of 60—70 feet; age, Recent. Subgenus SUBZEIDORA Iredale Iredale, 1924, Linnean Soc. New South Wales Proe., v. 49, p. 217. Type (by original designation): Emarginula con- nectens Thiele. Recent, Kermadec Islands. Emarginula (Subzeidora) souverbiana Pilsbry Plate 2, figures 17, 18 Emarginula maculata Souverbie, 1872, Jour. conchyliologie, v. 20, p. 55, pl. 1, fig. .6. Emarginula souberbiana Pilsbry, 1890, Manual Conchology, V. 12, p. 262, pl. 64, fig. 28. Small, thin, moderately convex, elongate-oval in out- line, slightly narrowed in front; sides arched so that shell rests on extremities; apex posterior, incurved; anterior slope gently convex, posterior slope flat; slit narrow, exceeding one-third total length of shell; margin of shell finely crenulated; nacreous within. Sculpture con- sisting of 24 primary radial ribs, alternating with an equal number of secondary ribs; surface cancellated by close-set concentric lirae. Measurements of the figured specimen (E—l, Eni- wetok, 10—20 ft), USNM 648233: length 3.0 mm, width 1.9 mm, convexity 0.9 mm. The two fossil specimens referred to E. souverbiana are small and may be immature; they are proportion- ately flatter than the typical Recent shells. Occurrence: Drill hole E—«l, Eniwetok Atoll at a depth ' of 10—20 and 30—35 feet; age, Recent. The Recent types The Eniwetok fossils are similar to E. clypeus A. . Adams (1851, p. 83), a Recent species from the Philip- were collected in New Caledonia. Emarginula (Subzeidora) sp. A Plate 2, figures 19, 20 Minute, broadly oval, highly arched forward from posterior; incurved apex, profile beneath apex gently convex; split open for about one-third of total length. Sculpture consisting of about 20 strong radial ribs beaded by concentric lirae. Internally the platform beneath the apex is inconspicuous. Measurements of the figured specimen, USNM 648234: length 2.1 mm, width 0.9 mm, convexity 0.6 mm. The single fossil appears close to, and may be iden- tical with, the Recent type species E. connectens Thiele from the Kermadecs, but it is even smaller than that species and may be immature. Adequate figures of the PALEONTOLOGY type species are not available, and I have not seen speci— mens. E. sp. A also appears to be closely related to E. sublathrata Pilsbry from Hawaii, but the fossil is narrower and more inflated posteriorly than is the Recent shell. Occurrence: Drill hole 2B, Bikini Atoll at a depth of 1,807—1,819 feet; early Miocene (Tertiary e). Emarginula (Subzeidora) sp. B Plate 2, figures 21, 22 Minute, highly arched, laterally compressed; outline from below subrcctangular; apex posterior, strongly in- eurved, anterior slope gently convex; posterior slope flattened below apex; slit long and narrow, open for more than one-third of total length. Sculpture consisting of about 20 strong primary radial ribs alternating with an equal number of finer secondary ribs; close—set concen- tric lirae over entire shell give a cancellated appear- ance; the more prominent lirae forming beads where they cress primary ribs. Anterior part of shell, below a line extending from upper end of slit to margin on each side at points below the apex, colored dark green; a small spot of green crosses selenizone a short distance above slit; remainder of shell white and translucent. B'Ieasurements of the figured specimen, USNM 648235: length 2.2 mm, width 1.4 mm, convexity 1.0 mm. The single fossil specimen appears to be much more compressed laterally than other described species. The fossil may represent an unnamed species,~but it could be an unusual or immature specimen. A name is with— held pending the recovery of additional material. Occurrence: l)rill hole F—l on Eniwetok Atoll at a depth of 20—45 feet; age, Recent. Genus HEMITOMA Swainson Swainson, 1840, Treatise on malacology, p. 356. Subgenus HEMITOMA 5.5. Type (by monotypy): Pal‘clla trz'cosliata Sowerby ~:-_P(1tella octm‘adiata Gmelinl. Recent, West Indies Hemitoma (Hemitoma) sp. Plate 2, figure 23 Large, low, ovate in outline; posterior slope flat; sclenizone inconspicuous; slit a shallow marginal inden- tation. Sculpture consisting of about a dozen rather regularly spaced broad but sharp-crested ribs that cause crenulation on the margin of the shell; two or more secondary ribs lie between each two primary ribs; all ribs made slightly scaly by irregular concentric lirae. Measurements of the figured specimen, USNM 648449: length 28.8 mm, width 22.6 mm. 29 The single Fijian fossil, seated upon a worn coral pebble, is incomplete, the apical area being worn away. It is larger, less convex, and less regularly ribbed than H. ossea (Gould), a Recent species known only from Fiji. Occurrence: In the Ndalithoni Limestone; age, prob- ably Pliocene (Tertiary h); Vanna Mbalavu, Fiji (sta. 110B). Subgenus MONTFORTIA Recluz Recluz, 1843, I. Travaux inédits catalogue descriptif de plusicurs nouvelles espéces de coquilles des mers de la France, p. 259. Type (by subsequent designation, Iredale, 1915, New Zealand Inst. Trans. and Proc., v. 47, p. 435): Ewar- gz'mdu australis Quoy and Gaimard. Recent, Australia. Hemitoma (Montfortia) bikiniensis Ladd, n. sp. Plate 2, figures 24, 25 Small, moderately arched, broadly ovate in outline; anterior slope convex, posterior slope concave immedi- ately below apex; anterior slit broad and short; internal groovedistinct. Sculpture consisting of about a dozen large rounded radial ribs, between each two of which lie one to three small rounded ribs; concentric lirae form low nodes that are particularly prominent on the larger ribs; margin of shell crenulated. Measurements of the holotype, USNM 648236: length 4.8 nnn, width 3.6 mm, convexity 2.0 mm. H. bikiniensis is smaller than the type species H. aus— trall's, is less convex, and has more strongly developed concentric structure. Occurrence: Holotype from drill hole 2 on Bikini Atoll at a depth of 105 feet; a second specimen in hole F-1 on Eniwetok at depth of 45~55 feet; both occurrences probably Recent. Hemitoma (Montfortia) sp. A Plate 2, figures 26, 27 Small, depressed, subrectangular in outline, thin; an- terior slope gently convex, posterior slope (below apex) flat; apex about two-thirds of length from anterior mar- gin; slit narrow, moderate in length; internal groove shallow. Sculpture consisting of about 20 poorly marked radial ribs of which 4, extending roughly to the corners, are larger than the others; concentric lirae obscurely developed. Measurements of the figured specimens (E—l Eni- wetok, 35—40 ft), USNM 648237: length 3.0 mm, width 2.1 mm, convexity 1.2 mm. The fossils may be related to H. ossea (Gould), a Recent species collected in Fiji. H. ossea, however, is a larger, heavier, and more coarsely marked shell whose apex is more centrally located. The type and only speci- 30 men of H. ossea is worn, and detailed comparisons are not possible. Occurrence: Represented by a total of 10 specimens, all small and possibly immature, from shallow depths (30—60 ft) in drill holes E—l and F—l on Eniwetok Atoll; age, Recent. Subgenus MONTFORTISTA Iredale Iredale, 1929, Queensland Mus. Mem., v. 9, p. 267. Type (by original designation): Montfortia excerz- trz'ca Iredale. Recent, North Queensland. Hemitoma (Montfortista) excentrica (Iredale) Plate 2, figures 28, 29 Montfortiu (illonlfmtistu) erecnlrim Iredale, 1929, Queensland Mus. Mem., V. 9, p. 267, pl. 31, figs. 14, 15. Medium, highly elevated, slightly compressed later- ally; anterior slope broadly convex, posterior slope eon- cave. Sculpture consisting of about 20 strong ribs, the anterior rib being strongest; traces of secondary ribs between some of main ribs; strong concentric lirae give the shell a deeply pitted appearance. Measurements of the figured specimen, USNM 648238: length (incomplete) 9.2 mm, width (incomplete) 6.6 mm, height 7.7 mm. The single fossil specimen is incomplete, but there appears to be little doubt that it represents H. excentrfca, a Recent shell from the Queensland coast. Occurrence: From coral pit (USGS 21029) on Espiritu Santo, New Hebrides, at altitude of 215- feet; age, Pleisto- cene or Recent. Genus RIMULA Defrance Defiance, 1827, Dictionnaire Sci. Nat, V. 45, p. 471. Type (by subsequent designation, Gray, 1847, Zool. Soc. London Proc., v. 15, p. 147): Rimula blar’nvz'lli De- france. Eocene, France. Rimula closely resembles Emerginula but the slit is partly closed, leaving a hole about half way up the anterior slope. This feature first appeared on species that developed during the Lower Cretaceous. Living examples are widely distributed in the warmer parts of the Pacific and the Atlantic. The only fossil repre— sentatives of the genus in the Pacific island collections are from the Marshall Islands. A single specimen identi— fied as R. exquisita was obtained from beds probably of Pliocene age on Bikini. Three small Recent shells from near the surface on Eniwetok are probably imma- CHITONS AND GASTROPODS FROM WESTERN ture. A single somewhat worn shell from a depth of more than 2,000 feet on Eniwetok is Miocene (Tertiary ‘ e) and appears to represent a second species. PACIFIC ISLANDS Rimula exquisite A. Adams Plate 2, figures 30, 31 Rimula exquisite A. Adams, 1851, Zool. Soc. London Proc., 19, . 226. Solwerby, 1862, Thesaurus conchyliorum 3, p. 210, figs. 3, 4. Pilsbry, 1890, Manual Conchology, v. 12, p. 270, pl. 64, figs. 3, 4. Medium in size, oval in outline; anterior slope broadly convex, posterior slope flattened; perforation long, slightly narrowed anteriorly; sculpture consisting of about 34 ribs that tend to alternate in size and are beaded by regularly spaced concentric lirae. Measurements of the figured specimen, USNM 648239: length 4.4 mm, width 3.0 mm, convexity 1.6 mm. Occurrence: The single immature fossil was obtained in drill hole 2A on Bikini Atoll at a depth of 447—453 feet; age, post-Miocene, probably Pliocene. Recent shells have been collected from the Philippines, Japan, and the Mariana Islands. Rimula sp. Plate 2, figures 32, 33 Small, oval in outline; margin erenulated, moderately convex, translucent; apex strongly recurved; perforation short, subrectangular. Sculpture consisting of about 20 strong radiating ribs that alternate with smaller sec- ondary ribs; primary ribs conspicuously beaded by reg— ularly spaced concentric lirae. Two of the three speci- mens available show traces of about eight broad radial bands of greenish brown. Measurements of the figured specimen, USNM 648240: length 1.9 mm, width 1.4 mm, convexity 0.9 mm. Occurrence: Drill hole E—l on Eniwetok Atoll at a depth of 10—20 feet; age, Recent. A single worn shell from hole F—l, Eniwetok, may represent this species; it was obtained from cuttings at a depth of 2,010—2,020 feet in Miocene beds (Tertiary e) but may have been derived from a higher level. Genus SCUTUS Montfort Montfort, 1810, Conehyliologie systématique, v. 2, p. 58—59. Type (by original designation): Scutus antipodes Montfort. Recent, southeast Australia. Subgenus NANNOSCUTUM Iredale Iredale, 1937, Australian Zoology, v. 8, pt. 4, p. 244. Type (by original designation) : Nannoscutum forsythi Iredale. Recent, Lord Howe Island, Australia. The shell of the type species of Narmoscutum is strongly lined concentrically, but even in this definitive feature it does not differ markedly from some of the shells ordinarily referred to Scutus s.s. Iredale, however, PALEONTOLOGY 3 1 has pointed out that the animal is unlike that of any previously described Scutus. Only two Specimens of scutid shells are found in the collections of island fossils. Both are from drill hole on Eniwetak Atoll in beds re- ferred to Tertiary 9. Both are small, as is the type of Nannoscutum, both show strong concentric sculpture, and each has a thickened margin that indicates adulthood. They differ in detailed sculpture, however, and may represent distinct species. Neither shell is complete, and this fact coupled with their rarity makes it unwise to attach specific names. They are described and figured as species A and B. The scutids are an Indo-Pacific group. In life the animals appear sluglike, because the flattened shells are partly or completely covered by the mantle. They are know to inhabit shallow water and to be light sensitive. lredale found the type species of Nannoscutum living under stones. Scutus (Nannoscutum) sp. A Plate 2, figures 34, 35 Shell marked posteriorly (anterior end missing) by six strong concentric ridges whose interior margins are wavy; outer ribs widely spaced with fine secondary ribs in the intervening de- sniall, depressed, stout, pressions. Measurements of the figured specimen, USGS 648241: width 7.1 nnn, convexity 2.8 nnn. Occurrence: Drill hole F—l, Eniwetok Atoll at depth of 720—730 feet; late Miocene (Tertiary g.) Scutus (Nannoscutum) sp. B Plate 2, figures 36, 37 Shell small, thin, outer parts marked by wavy con— centric ridges; area ncar apex comparatively smooth but bearing fine concentric lines that are bent backward along the median line of the shell. Measurements of the figured specimen, USNM 648242: length (incomplete) 5.3 mm, convexity 1.5 mm. The single incomplete shell resembles the genotype .V. forsyl‘hi but appears to have been more strongly in- dented anteriorly. A comparison with actual specimens of the type might reveal other distinctions. Occurrence: Drill hole K—IB, Eniwetok Atoll at a depth of 7684779 feet; late Miocene (Tertiary g). Genus DIODORA Gray Gray. 1821. Nat. Arrangement of Mollusca. London Med. Re- pository, v. 15, p. 233. Type (by monotypy): Patella apertura Montagu (z Patella graeca Linnaeus). Recent, Mediterranean Sea. Subgenus ELEGIDION Iredale Iredale, 1924, Linnean Soc. New South Wales Proc., v. 49, p. 220, pl. 35, figs. 5, 6. Type (by original designation): Elegidion audarc Ire- dale. Recent, Australia. Elegidion includes species in which the perforation lies wholly on the anterior slope. Diodora (Elegidion) marshallensis Ladd, n. sp. Plate 3, figures 1, 2 Small, ovate, conical; slopes nearly straight; apex prominent, perforation broadly oval or elliptical, located immediately anterior to apex. Sculpture consisting of about 18 sharply elevated ribs that increase in size from apex to shell margin where they form hollow crenulations on the inner surface of the shell; a single secondary rib is intercalated between each 2 primary ribs, but the secondaries are small and cause only minor crenulations on the shell margin; both sets of ribs crossed by con- centric lirae that become progressively larger near the shell margin where they form prominent beads on the primary ribs. The type specimens retain traces of eight dark green rays, the color being limited in each speci- men to a single primary rib. 1\'Ieasure1nents of the holotype (pl. 3, figs. 1, 2; E—l, Eniwetok, 700—710 ft), USNM 648243: length 3.4 mm, breadth (incomplete) 2.4 mm, height 1.5 mm. Shells referred to this species can be easily differen- tiated from those of D. aff. D. granifera (Pease) (see below), which occur in post—Tertiary beds in Eniwetok drill holes. I). marshallensis is heavier, has a much sharper sculpture, and a greater contrast in size between the two sets of ribs. The perforation of D. mm‘shallensis is oval to elliptical rather than elongate and is closer to the apex than in the younger species; likewise, in D. )narshallensis each of the green rays is limited to a single primary rib. Occurrence: The types and a half dozen other speci— mens from deep drill holes on Eniwetok in cuttings from depths of 700—852 feet in beds assigned to late Miocene (Tertiary g); two apical fragments from lower levels (873—915 ft) are from section referred to Tertiary f and may have been derived from younger beds. On Bikini a single apical fragment was recovered in hole 2B from the 789—800 feet interval (Tertiary g). Identifiable frag- ments also obtained from the marls at the base of the Palau Limestone in the Goikul area, Babelthuap, Palau (USGS 21301); late Miocene (Tertiary g). Diodora (Elegidion) aff. D. granifera (Pease) Plate 3, figures 3, 4 Small, oval in outline, slightly narrower in front, coni- cal; posterior slope slightly concave near apex, other 32 slopes nearly straight; apex prominent, projecting posteriorly; perforation elongate, located on the anterior slope. Sculpture consisting of 30 or more radial ribs with a tendency to alternate in strength; ribs beaded by weaker concentric lirac. Two of the five fossil specimens show traces of about 10 green radial bands Visible inside and outside the shell. Measurements of the figured specimen, USNM 648244: length (incompletel 3.0 111111, width 2.4 111111, height 1.4 111111. The Eniwetok fossils are identical with several Recent shells collected in surface float on the atoll and appear to be closely related to the variable I). granifem known from many localities in Hawaii. (Pease, 1861, p. 244; Pilsbry 1890, p. 407, pl. 63, fig. 13). The Eniwetok shells on the average are smaller, and their radial ribs have a stronger tendency to alternate in size than do those of the Hawaiian shells. Occurrence: Five specimens from four drill holes on Eniwetok Atoll at depths of 5—20 feet. Diodora (Elegidion) sp. A Plate 3, figures 5, 6 Medium in size, o'vate, highly conical; slopes gently convex; perforation small, broadly oval, located only slightly anterior to apex. Sculpture consisting of about 40 strong radial ribs that alternate with a second set of much smaller ribs; ribs conspicuously beaded by con— centric lirae that increase only slightly in size from apex to shell margin. iVIeasurements of the figured specimen, USNM 648245: length 14.8 111111, width 10.1 111111, height (incomplete) 8.6 111111. D. sp. A does not appear to be closely related to de- scribed fossil or Recent species. It may represent a new form, but neither of the two specimens available would make a satisfactory type. D. sp. A is much larger, proportionately higher, has more convex slopes, and is more conspicuously cancellate than D. marshallensis Ladd, n. sp., which occurs with it. The concentric lirae of D. sp. A are, likewise, more uni- form in size than those of D. marshallensis. Occurrence: Two specimens from the marls at the base of the Palau Limestone in the Goikul area, Babelthuap, Palau (USGS 213041; age, late Miocene (Tertiary g). An incomplete and poorly preserved speei111en from the Palau Limestone close to the volcanic contact on Aulup- tagel ([‘SGS 177151 may represent D. sp. A. Family PATELLIDAE Genus PATELLA Linnaeus Linnaeus, 1758, Systema naturae, 10th ed., p. 780. CHITONS AND GASTROPODS FROM W'ESTERN PACIFIC ISLANDS Type (by subsequent designation): Fleming, 1818, Enclopedia Britannica, supp—not seen: Patella vulgata Linnaeus. Recent, seas of Europe. Subgenus SCUTELLASTRA H. and A. Adams Scutellastra H. and A. Adams, 1854, Genera Recent Mollusca, v. 1, p. 466. Type (fide Keen, 1960, Treatise on invertebrate paleontology, Mollusca 1, p. 1235): Patella plicata Born :Patella barbara Linnaeus. Recent, southwest Pacific. Patella (Scutellastra) stellaeformis Reeve Plate 3, figure 7 Patclla stellaeformis Reeve, 1842, Conchyliologie systématique, v. 2, pl. 136, fig. 3. Pilsbry, 1891, Manual Conchology, v. 13, p. 98, pl. 17, figs. 25—27; pl. 61, figs. 62—65. An internal mold believed to represent this variable and widely distributed weStern Pacific species was ob— tained from a shallow drill hole, F-23C at depth of 85—88 feet, on Engebi Island, Eniwetok; age, probably Recent. The mold is low, conic, irregularly oval in outline; six major ribs radiate from the near-central apex; margin crenulated. Measurements of the figured specimen USNM 648246: length 9.1 mm, width 6.7 mm. The species occurs from east Africa to eastern Poly- nesia and is found in abundance today on the reefs of Eniwetok and other Marshall Island atolls. Genus CELLANA H. Adams H. Adams, 1869, Zool. Soc. London Proc., p. 273. Type (by original designation): Nacella cernica Adams. Recent, Mauritius. Cellana afi. C. sagittata (Gould) Helez'oniscus at'f. xagiltam Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 350, pl. 50, fig. D. No additional material was collected, and identifica- tion remains uncertain. As previously pointed out, the fossil shells (14 specimens) from the Ndalithoni Lime- stone, probably Pliocene (Tertiary h), on Vanua Mba- lavu, Fiji (stas. 110B, 110C) are slightly more elongate and somewhat less convex than the Recent shells (Gould 1846, p. 148; 1852, p. 337; 1856, Atlas, figs. 449a—c) and may represent a distinct species. Recent shells of C. sagitfata have apparently not been found outside Fiji. Cellana sp. A Plate 3, figure 8 Medium in size, thick, oval, a little narrowed an- teriorly, depressed conical; apex slightly anterior. Sculp- ture consisting of about 22 strong rounded radiating ribs, each of which, near the margin of the shell, hears 3 or 4 PALEONTOLOGY 33 low secondary riblets; concentric lines of growth are obscure on the worn shell but more prominent near the margins than elsewhere. Measurements of the figured specimen, USNM 648247: length 28.2 mm, width 24.3 mm, height (apex slightly broken! 8.6 nnn. The marginal secondary riblcts seem to differentiate the fossil from described species, but the single specimen is worn and broken. Occurrence: In the 'l‘anapag Limestone of Saipan tl'SGS 178911 ; age, probably Recent. Cellana? sp. Ilclrionisclm'.’ sp. Ladd. 1934. B. 1’. Bishop Mus. Bull. 119, p. 200. pl. 34, figs. 13. 14. Occurrence: A single, specimen from the marls of the Suva Formation, Viti Levu, Fiji (sta. 3051 ; age, Miocene (Tertiary fl. No additional material collected; identifi- cation remains questionable. Family TROCHIDAE Trochids are well represented on the island reefs today and apparently they were equally abundant during all of late Tertiary and Quaternary time. A total of 28 fos- sil species haVe been recognized. These have been placed in 12 genera and 15 subgenera. There are, in addition, numerous internal molds of trochids that are too poorly preserved even for generic determination. “Many of these are large forms, and most of them were collected from elevated and recrystallized reef limestones. Genus EUCHELUS Philippi Philippi. 1847. Zeitschr. Malakozool., v. 4, p 20. Subgenus EUCHELUS 5.5. Type (by subsequent designation, Herrmannsen, 1847, Indicis Generum Malaeozoorum 1, p. 430: Trochus quadricarinatus Dillwyn. Recent, Indian Ocean. Euchelus (Euchelus) cf. E. quadricarinatus (Dillwyn) Plate 3, figures 9, 10 Small, globose; whorls rounded, sutures impressed; deep umbilicus partly filled by a spiral fold; aperture subeircular, columella thin, straight with a poorly devel- oped basal tooth. Sculpture consisting of 12 spiral ribs of which 4 are more prominent than the others; larger ribs beaded by axial lamellae; secondary ribs between primary ribs are inconspicuously beaded; 4 or 5 ribs cover the base; 011 the figured specimen the rib bound- ing the umbilicus is larger than the other basal ribs. Measurements of the figured specimen (K—lB, Eni- wetok, 663—674 a), USNM 648253: height 3.7 mm, ' diameter 3.4 111111. Occurrence: Eight specimens from four drill holes on Eniwetok Atoll at depths to 120 feet; age, Recent; a single specimen from a fifth hole (K—lB) at a depth of 663—674 feet is from sediments referred to the late Mio— cene (Tertiary g), but this specimen is incomplete and may have been derived from a higher level. The fossil specimens appear to be closely related to, if not identical with, the type species that lives in the Indian Ocean (Pilsbry, 1889, p. 439, pl. 38, figs. 9—11). The fossils are immature and deeply umbilicate, as are young shells of the living species; the basal columellar tooth is only poorly developed on the fossils. Subgenus HERPETOPOMA Pilsbry Pilsbry, 1889, Manual Conchology. v. 11, p. 430. Type (by original designation): Euchelus scabrius- culus A. Adams and Angas. Recent, Australia. Euchelus (Herpetopoma) instrictus (Gould) Plate 3, figures 11—13 'l'rochus (Monodonta) instrictus Gould, 1849, Boston Soc. Nat. History Proc., v. 3, p. 107. Gould, 1852, US. Explor. Exped, Mollusca, p. 190. Gould. 1856, US. Explor. Exped, atlas, fig. 225a—c. Euchelus instrictus Gould, 1862, Otia Conchologica, p. 245. Pilsbry, 1889. Manual Conchology, v. 11. p. 440, pl. 67, figs. 62, 63. Johnson, 1964, US. Natl. Mus. Bull. 239, p. 92. Small, ovate—conic, stout; whorls moderately inflated, separated by a prominent channel; body whorl with 10-11 sharply elevated spiral ribs, the 3 nearest the periphery being the most prominent; ribs beaded by : close—set axial lamellae; base rounded; umbilicus nar- row; columellar tooth large, with a deep basal notch be- low; outer lip strongly lirate within, its thin edge crenu- lated by the surface ribs. Measurements of the figured specimen (E—l, Eniwe- ‘ tok, 30—40 ft) USNM 648254: height 4.1 mm, diameter 3.8 mm. Occurrence: Represented by 14 specimens from drill holes on Eniwetok at depths as much as 120 feet in Quaternary beds. A single shell from E—l at a depth of 620—630 feet is in the top of the section referred to the Miocene (Tertiary 9) but may have been derived from a higher horizon. Gould’s type specimen, a Recent shell (USNM 5625), was collected in the Pacific, exact 10- cality not stated. Living specimens have been collected in Fiji, and the species is common in the northern Mar- shall Islands. Euchelus (Herpetopoma) instrictus suvaensis Ladd, n. subsp. Plate 3, figures 14—16 Small. conic, thick; whorls moderately inflated, the body whorl separated from penultimate by channel; 34. CHITONS AND GASTROPODS FROM \VESTERN PACIFIC ISLANDS body whorl with nine strong spiral ribs that are coarsely beaded by axial lamellae; base convex, umbilicus closed; columellar tooth stout with deep basal notch below; inner edge of outer lip strongly lirate. Measurements of the holotype, USNM 648255: height 3.6 mm, diameter 3.3 mm. The fossil resembles Recent examples of E. instrictus from the same area but is more coarsely sculptured and has a covered umbilicus. Occurrence: Represented by a single specimen from the conglomerate at the base of the limestone in the type section of the Suva Formation, Viti Levu, Fiji (sta. 160) ; age, Miocene (Tertiary f). Subgenus VACEUCHELUS Iredale Iredale, 1929, Queensland Mus. Mem. 9, p. 272. Type (by original designation): Euchelus angulatus Pease. Recent, Anaa, Tuamotu Archipelago. Euchelus (Vaceuchelus) angulatus Pease Plate 3, figures 17—19 Euchelus angulatus Pease, 1867, Am. Jour. Conchology, v. 3, p. 283, pl. 23a, fig. 27. Euchelus frrvcoluhm ungulalus Pease. Pilsbry. 1889, Jour. Con— chology, \'. 11. p. 437, pl. 38, fig. 1. Euchelus (Vaceuchelus) angulatus .Pease, Iredale, 1929, Queens- land Mus. Mem. 9, p. 272. Small, globular, turreted, stout, nacreous within, im- perforate or narrowly umbilicate; columella without basal tooth; whorls convex, marked with strong spiral ribs crossed by well—developed axial lamellae that give ribs a beaded appearance and form deep pits in spaces between ribs. Body whorl with six to eight ribs, the three nearest the periphery larger than the others. Measurements of the figured specimen (E—1, Eniwe- tok, 40—50 ft), USNM 648256: height 3.0 mm, (limneter (incomplete) 2.5 mm. The fossil occurrences are apparently the first to be recorded. The strongly cancellated sculpture and the absence of a columellar tooth easily distinguish this form from all related species. Comparison with several lots of Recent shells indicates that the fossils fall within the limits of variation of such shells. The strong ribs vary in number from five to seven and the relative prominence of the peripheral members of the series also varies somewhat. The presence or absence of a narrow umbilicus does not seem to be a feature of significance. Occurrence: A single specimen from the conglomerate at the base of the limestone section of the Miocene (Tertiary f) Suva Formation, Viti Levu, Fiji. Two speci— mens from Quaternary beds in drill holes 2 and 2A on Bikini Atoll, depths of 100—285 feet; two specimens were recovered from drill hole E—l on Eniwetok at depths of 10—50 feet; age, Recent. Type locality of Recent shell is the island of Anaa in the Tuamotus; species also collected in the Society and Marshall Islands and reported from Fiji, Philippines, and Ceylon. Euchelus (Vaceuchelus) sp. A Plate 3, figures 20—22 Minute, conical, stout, narrowly perforate; aperture subcircular, columella straight, thin, without basal tooth; whorls flattened, sutures deeply impressed. Sculpture consisting of strong spiral ribs, 10 being present on body whorl; peripheral rib and the one immediately below it are larger than those above and than the 5 on the base; ribs crossed by slightly oblique axial lamellae to produce a pitted surface. Upper surface of whorls marked at fairly regular intervals by narrow reddish-brown axial bands. Measurements of the figured specimen (E—l, Eniwe- tok, 30—40 ft), USNMV648257: height 2.8 mm, diameter 2.6 mm. Easily differentiated from E. cf. quadricarinatus, pre- viously described, by the flatness of the whorls and the absence of the basal tooth. In general form and sculp- ture the fossil resembles Antillachelus (Miocene to Re- cent, ‘West Indies), but in that group there is a wide umbilicus and a heavy basal tooth and the aperture is lirate within. Occurrence: Two specimens at shallow depths (22— 40 ft) from drill holes on Eniwetok Atoll; age, Recent. Genus HYBOCHELUS Pilsbry Pilsbry, 1889, Manual Conchology, v. 11, p. 430. Type (by original designation) : Stomatella cancellata Krauss. Recent, Cape of Good Hope. Hybochelus cancellatus orientalis Pilsbry Plate 3, figures 23, 24 Eur'lwlus (Hy!uu‘h(’ht:<) cmzccllnlus nrir'nlalis Pilsbry, 1904. Aead. Nat. Sci. Philadelphia Proc., p. 35, pl. 6, figs. 57, 57a. Small, turbinate, depressed; body whorl large, suture deep; aperture ovate, oblique; umbilicus narrow, deep. Sculpture consisting of strong spiral ribs alternating with smaller secondary ribs, there being 10 primary spirals at the beginning of the last whorl; spirals crossed by oblique axial ribs to form deep, narrow pits; lowest of primary ribs spirals into the umbilicus. Traces of spots of brown on some of spiral ribs. Measurements of the figured specimen (E—l, 50—60 ft), USNM 648258: height (incomplete) 3.6 mm, diame- ter (incomplete) 4.7 mm. PALEONTOLOGY The fossil specimens are small; one is incomplete, the ‘, other immature, neither specimen shows the threads of l a third order mentioned by Pilsbry, though some of the Recent Marshall Island specimens do show this feature. Occurrence: Two specimens from drill holes on Eni— wetok Atoll at a depth of 29—60 feet; age, probably Re- cent. The species is a common one on the atoll today and was also collected at nearby Rongelap and Rongerik Atolls; Pilsbry’s types were collected in Japan. Hybochelus kavoricus Ladd Plate 3, figures 25, 26 Euchelus (Hybochelus) kavoricus Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 353, pl. 50, figs. J, K. No additional material collected. Holotype and only specimen from Ndalithoni Limestone; age, probably Pliocene (Tertiary h); Vanua Mbalavu, Fiji, (sta. 110B). As noted in the original description, H. Icanoricus differs from H. cancellatus orientalis chiefly in having fewer spiral ribs. Genus THALOTIA Gray (iray, 1840, Synop. contents British Mus, p. 147. Subgenus THALOTIA 5.5. Type (by subsequent designation, Gray, 1847, Zool. Soc. London Proc., p. 145): Trochus pictus Wood: Monodonta com'ca Gray. Recent, Australia. Thalotia (Thalotia) berauensis (Beets) Plate 3, figures 27, 28 Cunlhm‘idus (Canlharidus) berauensis Beets, 1941, Geol.-mijnb. genootseh. Nederland en Kolonien Vol-11.. (leol. ser., v. 13. pt. 1, p. 13—14, pl. 9, figs. 338—340. Small, broadly conical, stout, imperforate; spire flat, periphery of body whorl rounded; aperture ovate, lirate within; columella inclined with a strong nearly hori- zontal basal tooth. Whorls marked by spiral ribs con— spicuously beaded by inclined axial lamellae; on body whorl the 5—6‘ ribs above the strong peripheral rib are subequal in size; the 5—6 ribs on the base below the periphery are variable in size; axial wrinkles are well de- veloped on the early whorls, 9—11 being on the penulti— mate whorl. Measurements of the figured specimen, USNM 648259: height 5.2 mm, diameter 3.4 mm. Occurrence: Originally described from the upper Mio- cene of East Borneo. Three specimens found in drill hole Kl—B on Eniwetok Atoll at a depth of 1,070—1,081 feet in beds referred to lower Miocene (Tertiary f). 35 Thalotia (Thalotia) eff. T. elongatus (Wood) Plate 3, figure 29 Narrowly conical, heavy; periphery rounded, sutures slightly impressed, imperforate. Sculpture consisting of two spiral rows of heavy nodes and finer spiral ribs; base with close—set spiral ribs. Measurements of the figured specimen, USNM 648260: height 22.2 mm, diameter 15.3 mm. The single fossil is complete, but the shell is recrystal- lized and most sculptural features are obscured. It re- sembles the Recent T. elongatus (Wood, 1828, pl. 5, fig. 19) in its unusual height of spire and its heavy nodes that tend to form longitudinal plications. On the fossil, the nodes are larger and the rows are more distinctly separ- ated than on the Recent shells. When better material is obtained, the fossil may prove to be a distinct species. T. elongatus was described from New Caledonia tPils- bry, 1889, p. 143, pl. 45, fig. 56), but it is also known from Japan. During Operation Crossroads in the Marshall Islands, a single dead shell was collected from the lagoon shore of Eniwetok Atoll. Occurrence: In the Mariana Limestone tl'bGS 20574) ; age, probably Pleistocene. of Guam Subgenus Beraua Beets Beets. 1941. Geol.—Inijnb. genoolseh. Nederland en Kolonien Verh., Geol. ser., v. 13, pt. 1, p. 14. Type tby original designation): ('antharidus er’ina- ('eus Beets. Upper Miocene, Borneo. Thalotia (Beraua) sp. Plate 3, figure 30 Small, high-conical; base convex; early whorls flat sided with low axial plications; last two whorls with strong sutural nodes, all whorls and base bearing fine spiral ribs. Measurements of the figured mold, USNM 648261: height 9.7 mm, diameter 7.5 mm. The single specimen from Saipan is an incomplete external mold, but it does show the unique sutural nodes that characterize Beraua. It closely resembles the plumper form of the type species T. erinaceus, described by Beets from the Miocene of Borneo, but appears to have a more convex base. Specific identification must await better material. Occurrence: Inequigranular facies of Miocene (Tertiary e) Tagpochau Limestone, Saipan, Mariana Islands (L'SGS 17904). Genus TURCICA A. Adams A. Adams, 1854, Z00]. Soc. London Proc., p. 37. Type tby monotypy): Turcica monilifera A. Adams. Recent, Morton Bay, Australia. 36 Subgenus PERRINIA H. and A. Adams H. and A. Adams, 1854, Genera Recent Mollusca, 1, p. 419. Type (by subsequent designation, Pilsbry, 1889, Manual Conchology, v. 11, p. 419): Monodonta anguli— fera A. Adams. Recent, Philippine Islands. Turcica (Perrinia) morrisoni Ladd, n. sp. Plate 3. figure 31; plate 4, figures 1—5 Small, conic, stout, imperforate, nacreous within. Whorls with a prominent peripheral carina which is ex- tended into a series of flattened triangular spines that are regularly spaced (about 13 on the last whorl) and that give the shell a stellate appearance when Viewed from above; suture impressed. Above the peripheral carina are three beaded spirals, the uppermost one coarser than the other two; base has four beaded concentric spirals, the outer one the coarsest, its beads spinose. Aperture semi-elliptical, lirate within; columella strong, granulate, with a broad basal tooth; outer lip thin, its edge crenulated by the surface ribs. h'Ieasurements of the holotype, a Recent shell (pl. 3, fig. 31; pl. 4, figs. 1, 2), USNM 648262: height 3.3 mm, diameter 2.8 mm. Euchelus morrisoni is closely related to E. stellata , described by A. Adams from the China Seas, but both Recent and fossil examples of E. morrisoni are much smaller, have a broader apical angle (roughly 65° as against 450 for E. stellata), and the concentric ribs on the base are strongly beaded whereas those of E. stellata are not. Occurrence: Type lot (five specimens) collected alive from the undersides of coral blocks on the reef flat behind CHlTONS AND GASTROPODS FROM \VESTERN PACIFIC ISLANDS Genus GIBBULA Risso Risso. 1826. Histoire naturellc des principales productions de l’Europe méridionale, V. 4, p. 134. Subgenus GIBBULA s.s. Type (by subsequent designation, Herrmannsen, 1848, Indicis Generum Malacozoorum Primordia, p. 437): Trochus magus Linnaeus. Recent, Mediterranean Sea. Gibbula (Gibbula) engebiensis Ladd, n. sp. Plate 4, figures 6, 7 Shell small, conical, distinctly turreted with sutures impressed; moderately thick; aperture subcircular, smooth and pearly within; umbilicus narrow, bordered by a thick ‘beaded spiral ridge; inner lip callused, ex- panded a little above, more extensively below where it covers the end of the umbilical ridge. Sculpture consist- ing of primary and secondary spiral ribs inconspicuously beaded by fine axial lines of growth; on the body whorl there are four primary ribs, the middle two being slightly larger and forming a biangular periphery; secondary ribs are present between all primary ribs and on the base which is set off from the rest of the whorl by a sharp angle. Tracesiof original color in the form of wide, regu- larly spaced reddish-brown bands appear on the last two whorls and extend across the base of the body whorl; inner lip white. Measurements of the holotypc, only specimen, USNM 648264: height 2.9 mm, width 2.9 mm. The fossil species is tentatively referred to Gibbula ‘ s.s because it seems to fit better there than in any one i of the numerous subgenera that have been recognized. the seaward margin on the south side of Bokororyuru , Island, Bikini Atoll. This area is the “zone of blocks” in a measured traverse (Emery, Tracey, and Ladd 1954, p. 170—171); it lies 115—225 feet from the seaward edge, Collected by .l. P. E. Morrison. A few dead shells were found in drift samples from half a dozen localities on several islands of Bikini Atoll aid of Eniwetok Atoll; dead shells were found in abun— dance in a drift sample taken on Bock Island, Rongerik Atoll. Only two l‘ossil shells have been found. One of these shells is from a depth of 271/; feet in drill hole 2 on Bikini Island and is Recent in age; the other (USNM 648263, pl. 4, figs. 3—5) from a depth of 1,46%],472 feet in drill hole 28 on Bikini Island is from beds referred to the The type of the genus, G. magus (Linnaeus), is a medium- sized shell from the Mediterranean with a wider umbil- icus than that shown by the fossil and a less well devel- ( oped columellar callus. The fossil is much more closely related to G. gradafa (Gould), a species described from . . . l the Pacific islands (Gould, 1849, p. 91) and later from and its surface is covered by a foot of water at low tlde. ) the West Indies (as G. pisum, Philippi, Pilsbry, 1889, p. 241, pl. 31, figs. 38—40). The Recent shell is considerably , larger than the fessil, is more distinctly ribbed, and 011 Miocene (Tertiary f), but the single fossil picked from J the drill cuttings is slightly worn and may have been 1 derived from a younger horizon. the body whorl the uppermost of the four primary ribs is the largest; the Recent shell likewise has a wider um- bilicus than does the fossil. Occurrence: Drill hole Kl—B on Engebi Island, Eni- wetok Atoll, at a depth of 926—936 feet in beds referred to early Miocene (Tertiary f). Genus FOSSARINA A. Adams and Angas A. Adams and Angas, 1863, Zool. Soc. London Proc., p. 423. Type (by subsequent designation, Suter, 1913, Manual New Zealand Mollusca, p. 139): Fossarina patula A. Adams and Angas. Recent, Australia. PALEONTOLOGY Subgenus MINOPA Iredale Iredale, 1924, Linnean Soc. New South Wales Proc., v. 49, p. 226. Type (by original designation): Fossarina legrandi Pctterd. Recent, South Australia. Fossarina (Minopa) hoffmeisteri Ladd, n. sp. Plate 4, figures 8—10 Small, globose, thin; whorls inflated; suture impressed, descending at aperture; aperture subcircular, oblique; peristome slightly projecting at base of columella. Sculp- ture consisting of faint spiral threads and fine lines of growth; spirals are better developed on earlier whorls than on body whorl. Many examples from younger beds retain traces of original color in the form of widely spaced oblique bands and irregular pointed cross bands of red- dish brown. Measurements of the holotype (Mu—4, Eniwetok, 40 ft), USNM 648265: height 4.1 mm, diameter 3.8 mm. Occurrence: Twenty-four specimens from five drill holes on Eniwetok Atoll from near the surface to a depth of 670 feet; age, Recent to late Miocene (Tertiary 9); two drill holes on Bikini Atoll yielded five specimens, one from post-Miocene beds (core) at 2351/2 feet and four others from early Miocene (Tertiary 9) beds 1,335— 1,892 feet. The species still lives in the Marshall Islands but appears to be rare, as only a single dead shell was collected during Operation Croesroads. Genus ASTELE Swainson Swainson, 1955, Royal Soc. Van Diemensland Papers, v. 3, p. 38. Type (by monotypy) : Trochus subcarinatus Swainson. Recent, Tasmania. Subgenus CALLISTELE Cotton and Godfrey Cotton and Godfrey, 1935, South Australian Naturalist, V. 16, no. 2, p. 20. Type (by original designation) : Astele calliston Verco. Recent, Australia. Astele (Callistele) engebiensis Ladd, n. sp. Plate 4, figures 11—13 Small, conical, thin; protoconeh of about 11/2 smooth whorls; sides flat, base gently convex; aperature quadrate, within; vertical, slightly callused; umbilieus narrow, smooth sided; periphery nacreous columella nearly sharply angled, scalloped. Sculpture consisting of fine, closely spaced spiral ribs, five above periphery on body whorl, nine below periphery on base; ribs and interspaces crossed by numerous fine oblique lines. Measurements of the holotype, USNM 648266: height 2.7 mm, diameter 2.9 mm. 37 The Recent shell A. Calliston Verco described from Spencer Gulf, South Australia, has been the only species referred to Callistele. I have not seen specimens, but Verco’s figures show that the Recent shell has a more prominently projecting peripheral carina and fewer ribs on the base than does the fossil. Occurrence: Holotypc and only specimen from drill hole K-1B on Engebi Island, Eniwetok Atoll at a depth of 968e978 feet in beds assigned to early Miocene age (Tertiary f). Genus TROCHUS Linnaeus Linnaeus, 1758. Systema naturae, 10th ed., p. 756. Subgenus TROCHUS 5.5. Type )by subsequent designation, Iredale, 1912, Malacological Soc. London Proc., V. 10, p. 225) : Trochus maculatus Linnaeus. Recent, Indo-Pacific. Trochus (Trochus) maculatus Linnaeus Plate 4, figures 14, 15 Trochus maculatus Linnaeus, 1758, Systema naturae, 10th ed., p. 756. Trochus (Infundibulum) maculatus Linnaeus, Pilsbry, 1889. Man- ual Conchology, V. 11, p. 24, pl. 9, figs. 100, 1, 2, 3. Trochus maculntus Linnaeus. Demond, 1957. Pacific Sci.. v. 11, no. 3, p. 285. Identifiable specimens of the variable type of Trochus s.s. were recovered from 13 localities in the detrital de- posits and Agana Argillaceous Members of the Pliocene and Pleistocene Mariana Limestone of Guam (figured specimen from USGS 20636, USNM 648248) and from one additional locality (USGS 21383) on the island that may be referred to the upper Tertiary Alifan Limestone. Incomplete specimens that probably represent. this species were also collected from Quaternary beds on Saipan (Tanapag Limestone) and from an unnamed coastal limestone on Espiritu Santo Island in the New Hebrides. These fossil occurrences are not the first, be— cause the species has been reported from the Pliocene of Java and Quaternary of Timor and Billiton. Recent shells are widely known from Samoa to Fiji, the Philip- pines, the Ryukyus, Japan, Indonesia, and the Indian Ocean. Trochus (Trochus) histrio (Reeve) Plate 4, figures 16—18 Turbo hislrio Reeve, 1848, Z001. Soc. London Proc., pt. 16, p. 52. Trochus histrio Reeve, 1861, Conchlogica Iconica, v. 13, pl. 15, fig. 90. Trochus calcarams Pilsbry, 1889, Manual Conchology, V. 11, p. 30, pl. 2, fig. 15; pl. 8, figs. 83, 84. Trochus his-trio hislrio Reeve, Demond, 1957, Pacific Sci., v. 11, no. 3, p. 285, fig. 1. 38 Small; upper surface of whorls bearing six rows of rounded circular, elongate, and slightly oblique granules; basal row on upper whorls forming prominent open pustules, 15 on penultimate whorl; on last whorl granules become smaller, more uniform in size, and pustules are not open; base with 10 concentric rows of beads; on outer half of base, rows of fine beads alternate with rows of larger beads; pseudoumbilicus with 2 smooth spiraling plicac. Faded traces of original color, broad red axial bands on the spire and spiral lines of short red dashes on the base, are preserved on both fossil specimens from Eniwetok. Measurements of the figured specimen, USNM 648249: height 11.2 mm, diameter 13.4 mm. Occurrence: Cuttings from drill hole F—l, Eniwetok, at a depth of 110—120 feet (figured specimen); a frag- ment was also recovered from cuttings in the same hole at a depth of 80—90 feet; age, Recent. A worn specimen from the Miocene (Tertiary f) Suva Formation at V iti Levu (sta. 160), probably represents the same species. Recent shells were collected on reef at Eniwetok and from beach drift there and at Bikini. The species also is known from other western Pacific islands including Palau, Mariana, Ellice, Loyalty, Ryukyu, and Line groups and from southern Japan and the South China Sea. Trochus (Trochus) incrassatus Lamarck ’I'rtmhus incrassatus Lamarck. 1822. Hist. Nat. Animaux sans Vertébres, v. 7, p. 20. Reeve, 1861, Conehologica Iconica, v. 13, fig. 77. Pilsbry. 1889. Manual Conchology, v. 11, p. 26, pl. 6, figs. 48—50. Truchus incrassalus creniferus Kiener, Pilsbry, Conchology. v. 11, p. 27, pl. 7, figs. 67, 68. Ostergaard. 1935. Ipartl, B. P. Bishop Mus. Bull. 131. p. 46—47. 1889, Manual Represented by four incomplete and poorly preserved fossils from the shore rocks at Houma, Tongatabu, Tonga (sta. 3). J. M. Ostergaard collected the fossils and identified them with Recent shells from the same area referring them to T. incrassaz‘us creniferus Kiener. The fossils, however, are not strongly tuberculate around the periphery, as are shells commonly referred to Kiener’s variety. The base of the fossils is marked by 11 or 12 concentric ribs rather than the 7 or 8 normally shown by T. incrassatus. The fessils are probably Pleistocene. Recent shells have been reported from various island groups, including Tonga, Samoa, and Japan. Trochus (Trochus) tubiferus Kiener Plate 4, figure 19 Trachus tubifcrus Kiener, Fischer, 1880, Species general des co- quilles, vivantes, Troque, v. 37, fig. 3. Pilsbry, 1889, Manual Conehology, v. 11, p. 31, pl. 6, figs. 62, 63. Ostergaard, 1935, B. P. Bishop Mus. Bull. 131, p. 47. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Four specimens of this species, characterized by a row of pustules at the base of each whorl and by numerous lirae on the flattened base, were collected by Ostergaard from elevated limestone on Tongatabu, Tonga (stas. 2—4); age, probably Pleistocene. Measurements of the figured specimen from station 2, B. P. Bishop Museum, geology No. 1339: diameter 25.9 mm, height (incomplete) 20.8 mm. The Recent shells have been reported from Tonga, Fiji, Ellice Islands, Loyalty Islands, and New Caledonia in the southwest Pacific. Genus CLANCULUS Montfort Montfort- 1810, Conchyliologie systématique, v. 2, p. 191. Subgenus CLANCULUS 5.5. Type (by original designation): Troohus pharaonius Linnaeus. Recent, Red Sea. Clanculus (Clanculus) clanguloides fijiensis Ladd Plate 4, figures 20—22 Clanculus (Clanculus) clanguloides fijiensis Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 352, pl. 50, figs. H, 1. Type material (four specimens) collected from the Ndalithoni Limestone, probably Pliocene (Tertiary h), on Vanua Mbalavu in eastern Fiji; an incomplete mold from the so-called older limestone (possibly Tertiary f) of the island of Fulanga in the same area (sta. L-78) may also represent this species. Genus TECTUS Montfort Montfort. 1810. Conchyliologie systématique, v. 2, p. 187. Subgenus TECTUS s.s. Type (by original designation): Tectus pagodalis= Trochus mauritianus Gmclin. Recent, Indonesia. Tectus (Tectus) mauritianus (Gmelin) Plate 4, figure 23 Tmcllus mauritianus Gmelin, 1791, Systema naturae, 13th ed., p. 3582. Trot-him (Tectus) Miami/{units (imelin. l’ilsbry. 1899. Manual Conehology, v. 11, p. 23, pl. 2, figs. 11. 12; pl. 4, figs. 24, 25, 27. A single incomplete example of this widely distributed Recent Indo-Pacific type of the genus was collected by Harold Stearns from a limestone pit (USGS 21028) on Espiritu Santo Island, New Hebrides, at an altitude of 240 feet;’age, Quaternary. The characteristic projecting peripheral tubercles are well preserved on the fossil. Measurements of the specimen, USNM 648250: height (incomplete) 16.5 mm, width 17.4 mm. PALEONTOLOGY Tectus (Tectus) pyramis (Born) Trachus pyramis Born, 1778, Index Rerum Naturaeium Musei Caesarei Vindobonensis, pt. 1, Testacea, p. 338. Trochus obeliscus Gmelin, 1791. Systema naturae, 13th ed.. p. 3579. True/Ills (chlus) obeliscus (lmelin. Pilsbl'y. Conchology. V. 11. p. 19, pl. 2. figs. 13, 14. Ostergaard, 1935, B. P. BishOp Mus. Bull. 131, p. 47. 1889. Manual Ten poorly preserved but identifiable examples of this widely distributed western Pacific species were collected by Cloud and by Ladd from the Pleistocene Tanapag Limestone of Saipan (USGS 17387 and 21407 respec- tively). Ostergaard collected six specimens (identified as T. obeliscus Gmelin) from the sea cliff near Houma (sta. 3) on Tongatabu, Tonga, in rock that is probably late Pleistocene in age. Tectus (Tectus) cf. T. bomasensis (Martin) Plate 4, figure 24 Medium in size, conical, higher than wide; base flat, meeting the body whorl at a sharp angle; nonumbilicate but with a strong columellar fold that is bordered by a broad smooth groove. Sculpture consisting of a promi- nent double nodose spiral ridge at the base of each whorl; lower part of ridge larger than upper; above the peripheral ridge each whorl bears three beaded riblets; on the body whorl the grooves between each two riblets contains a fine spiral cord; base marked by about eight beaded concentric cords. Measurements of the figured specimen, USNM 648251: height 15.1 mm, diameter 13.6 mm. The single Fijian fossil is incomplete, but it appears to be closely related to, if not identical with, T. bomasensis described by Martin (1917, p. 261, pl. 3, figs. 90a, b) from the lower Miocene of Java. The fossil resembles T. fenestratus (Gmelin), a Recent species that occurs in Fiji and other Pacific and In- donesian islands. T. fenestratus is a variable species, and some shells show a dual ridge along the periphery, but it is not as prominent as in the fossil; the Recent shell is likewise much more strongly nodose than the fossil. Occurrence: Conglomeratic facies of the Mba series at locality MR»20, about 3 miles south of Mba, Viti Levu, Fiji, collected by M. R. Rickardof the Fiji Geological Survey Department; age, probably Pliocene (Tertiary h). Subgenus ROCHIA Gray Gray, 1857, Guide Systematic Distrib. Mollusea British Mus, pt. 1, p. 148. Type (by monotypy): Trochus acutangulus Chemnitz Recent, Indo-Pacific. Also reported from the Pliocene or Quaternary of Timor. :Trochus con us Gmelin. 39 Tectus (Rochia) niloticus (Linnaeus) Plate 4, figure 25 Trm'h'us nilolicus Linnaeus. 1767, Systema naturae 12th ed., no. 579, p. 1227. Pilsbry, 1889, Manual Concholog'y, v. 11, p. 17, pl. 1. figs. 5—8. Demond, 1957, Pacific Sci., v. 11, p. 285. MacNeil, 1960, US Geol. Survey Prof. Paper 339, p. 25, pl. 18, figs. 3, 5. ’I'rochus (Rochia) m'loticus Linnaeus, Ladd, 1934, B. P. Bishop Mus. Bull. 119, p. 202. Rippingale and McMichael, 1961, Queensland and Great Bar- rier Reef shells, Jacaranda Press, Brisbane, p. 31, fig. 19. A large and well-preserved example of this widely dis- tributed Recent species was collected by H. T. Stearns from a coral pit (USGS 21029) on Espiritu Santo Island in the New Hebrides at an altitude of 215 feet. Though part of the body whorl is broken, the shell (USNM 648252) shows its nacreous luster and traces of its orig- inal color pattern. The deposit is probably not older than Pleistocene. The species has also been reported from the Pliocene of Sumatra and Java and the Pliocene and Pleistocene of Okinawa. Genus ISANDA H. and A. Adams H. and A. Adams, 1854, Z00]. Soc. London Proc., for 1853, p. 189. Type (by original designation): Isanda coronata A. Adams. Recent, Australia, The genus Isanda includes small heavy polished tro- chids having an open umbilicus and smooth interior. They are widespread in the Indo-Pacific and Australian area. Subgenus PARMINOLIA Iredale Iredale, 1929, Queensland Mus. Mem. 9, p. 271. Type (by original designation) : Mineola agapeta Mel— vill and Standcn (_1896)=M0m’lea apicina Gould (1861). Recent, South Pacific. Isanda (Parminolia) apicina (Gould) Plate 5, figures 1—4 Monilea apicina Gould, 1862, Boston Soc. Nat. History Proc., p. 16. Monilea agapeta Melvill and Standcn, 1896, Jour. Conchology [Leeds] v. 8, p. 312, pl. 11, fig. 77. Mom'len apicinn Gould, Pilsbry, 1889, Manual Conchology, v. 11, p. 254. Johnson, 1964, US. Natl. Mus. Bull. 239, p. 41, pl. 14, fig. 4. The following description is based on the fossil mate- rial. Small, conical, solid; apex sharp, about five inflated whorls distinctly angled a short distance below suture and on body whorl, obscurely angled at periphery; aper- ture subcircular, outer lip thin, inner lip thickened, bear- ing a basal tooth and slightly scalloped by extensions 40 that cover the ends of two ribs that spiral into the um- bilicus; outer of two umbilical ribs larger and beaded; umbilicus narrow and deep. Sculpture consisting of close- set spiral ribs crossed by fine axial lines; ribs wider on base near umbilicus. Two of the fossils retain patches of reddish-brown on the upper parts of penultimate and body whorls. Measurements of the figured specimen, (E—l, 60—70 ft) USNM 648267: height 3.9 mm, diameter 4.0 mm. Gould’s type USNM 24159 (pl. 5, figs. 3, 4) measures: height 4.9 mm, diameter 5.9 mm. The Marshall Island specimens, both surface shells and those from drill holes, are smaller than Gould’s type and are less sharply angled below the suture; the second (lowerl funicle in the umbilicus is less well developed in the Marshall Island shells. Occurrence: Eight specimens from drill holes on Eni- wetok at depths from 1—243 feet; age, Recent; in Bikini drill holes, one specimen at 40 feet, three others at depths of 1,356—1,850 feet; the deeper specimens from the early Miocene (Tertiary c) . Gould’s type (USNM 24159) is labeled ”Coral Sea” but the published description cites Port Jackson [Syd- ney], Australia. The Recent shells described by Melville and Standen were collected in the Loyalty Islands. The species is common in collections of drift shells from both Eniwetok and Bikini. Genus MONILEA Swanson Swanson, 1840, Treatise 011 malacology, p. 352. Subgenus MONILEA s.s. Type (by monotypyl: Trochus calliferus Lamarck. Recent, Indo-Pacific; also reported from Pliocene of Java. Monilea (Monilea) mateana Ladd Plate 5, figures 5—8 Monilea (Monilea) muleana Ladd. 1934. B. P. Bishop Mus. Bull. 119, p. 203, pl. 35, figs. 1, 2. Small, solid; inner surface of outer lip has 10—12 strong lirations with small liration in interspaces; columella dentate below; umbilicus wide with a broad ridge or funicle spiraling up its side to terminate against the dentate part of the eolumella; funicle, in some speci- mens marked with a median groove. Sculpture consisting of strong spiral ribs beaded by axial striae. On the base the ribs are flattened and subequal in size; on the upper parts of the whorl, they are rounded, more strongly beaded and each second or third rib is larger than the others. Shell marked exteriorly by axial bands of red- dish brown. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Holotype: B. P. Bishop Museum, geology No. 1196 (pl. 5, figs. 5, 6): height 7.0 mm, diameter 8.0 mm. Figured specimen, USNM 648392 (pl. 5, figs. 7, 8) : height 6.7 mm, diameter 7.2 mm. Examination of additional specimens collected from the type locality (Viti Levu, sta. 160) has shown that the median depression in the funicle is a variable feature and that the internal lirations and surface ribs are less con- stant than formerly thought. M. mateana is most closely related to M. (Monilea) marshallensis Ladd, n. sp., a younger species from the Marshall Islands drill holes, described below. Occurrence: Many specimens from stations 160 and 160A, Viti Levu, and a single shell from station L493, Lakemba, Fiji; age, Miocene (Tertiary fl. Monilea (Monilea) marshallensis Ladd, n. sp. Plate 5, figures 9—12 Small, globular, solid; edge of outer lip thin, the thicker part within bearing 9 or 10 strong lirations; columella dentate below; umbilicus moderately wide, partly filled by a broad funicle. Sculpture consisting of strong spiral ribs beaded by axial striae; on the base the ribs may alternate with weaker ones. Holotype: USNM 648270: height 3.9 mm, diameter 3.4 nnn. Paratype A (USNM 648268): height 4.1 mm, diameter 4.1 nnn. ‘ The new species appears to be very closely related to M. mateana from the lower Miocene of Fiji. The Mar- shall Island fossils have a narrower umbilicus and show only one set of lirations within the aperature. Examples of M . marshallensis were not found in the collections of Recent shells made at Bikini and Eniwetok Atoll. Occurrence: Holotype from drill hole K—lB, Eniwetok Atoll at a depth of 1,248—1,259 feet; lower Miocene (Tertiary cl; numerous other Eniwetok occurrences range from near the surface to 880 feet (Recent to Ter- tiary fl. On Bikini, paratype A was recovered in drill hole 2A from core at a depth of 235 feet; age, post- Miocene; a dozen other Bikini occurrences range down- ward to 1,135 feet; age, Tertiary e. Monilea (Monilea) lifuana Fischer Plate 5, figures 13, 14 Truchus (Monilea) lifuamts Fischer, 1878, Jour. conchyliologie, v. 26, p. 63. .‘llunz'lea lifuana Fischer, I’ilsbry, 1889, Manual Conchology. 11, p. 252, pl. 41, figs. 6. 7; pl. 59, figs. 64. 65. Small, depressed, thin; body whorl inflated, broadly angled at periphery; aperture subquadrate, smooth within; inner lip thickened below; umbilicus narrow and I’Al.l".()NT()L()(:Y deep, partially filled by a heavy funicle. Sculpture con- sisting of fine spiral lines crossed by oblique axial lines of growth; axial lines more conspicuous on base near umbilicus than elsewhere. Measurements of the figured specimen, USNM 648269: height 5.2 mm, diameter 6.9 mm. Occurrence: A single specimen from drill hole En—4, Eniwetok Atoll, at depth of 2 feet; age, Recent. The species was described from the Loyalty Islands but has also been collected in Japan and on Bikini and Eniwetok Atolls in the Marshall Islands. One specimen was dredged alive from a depth of 180—200 feet in Bikini lagoon. Monilea (Monilea) belcheri (Philippi) Plate 5, figures 15, 16 Trochus belcheri Philippi, 1849, Zeitschr. Malakozool., p. 148. Monilea. (Monilea) belchcri Philippi. Pilsbry, 1889, Manual Conchology, v. 11, p. 250, pl. 61, figs. 3, 4. Medium in size, depressed; whorls inflated, suture deeply incised; aperture subquadrate, smooth within; outer lip thin; columella oblique; umbilicus moderately wide, partially filled by a strong spiral funicle. Sculpture consisting of about 30 short close-set spiral ribs that, on the upper surface, show a tendency to alternate in size. Measurements of the figured specimen, B. P. Bishop Museum, geology No. 1235: height 8.6 mm, diameter 11.1 mm. Occurrence: Single specimen from station 320, Viti Levu, Fiji; age, late Tertiary; a specimen with fewer ribs but probably representing the same species was col— lected from the Futuna Limstone at station 304 on the island of Lakemba in eastern Fiji; age, Miocene (Ter- tiary f). Recent shells are known from Tonga, Fiji, New Caledonia, and Japan. The fOssils are more strongly ribbed 011 the base and more uniformly ribbed above than are the Recent shells. Family STOMATELLIDAE Genus PSEUDOSTOMATELLA Thiele Thiele, 1921', Revision des Systemes Trochacea, p. 29. Subgenus PSEUDOSTOMATELLA 5.5. Type (by original designationt: Stonmtella papyraccu “Chenmitz,” A. Adams. Recent, Indo-Pacific. Pseudostomatella (Pseudostomatella) maculata (Quoy and Gaimard) Plate 5, figures 17, 18 Stomalcllu maculala Quoy and Gaimard, 1834, Voyage de l’Astro- lube. Zoologie. \'. 3. p. 305, pl. 66 (his), figs. 13—16. Reeve, 1874, Conchologica Iconica. v. 19, Stomatclla, pl. 1. fig. 5. Pilsbry. 1890. Manual Conchology. v. 12, p. 13, pl. 51, figs. 1749; pl. 52, figs. 60. 61. 41 Small, moderately elevated, with four inflated whorls; columellar margin flattened; sculpture consisting of spiral ribs; above the periphery the strongest of three sets of ribs are beaded by oblique axial striae; the middle- sized set of ribs shows traces of beading; below the periphery the ribs are less conspicuous. Measurements of the figured specimen, USNM 648271: height 10.5 mm, diameter (outer lip incomplete) 11.6 mm. Occurrence: Six specimens collected from the Ndali- thoni Limestone; age, probably Pliocene (Tertiary h); Vanua Mbalavu, Fiji (sta. 110B). The species, originally described from Recent shells from the Santa. Cruz Islands, has since been collected westward to Torres Straits, eastward to the Society Islands, and northward to the Marshall Islands. Genus STOMATIA Helbling Helbling, 1779, Abh. Privatgesell., Prag, v. 4, p. 124, pl. 2, figs. 34, 35. Type (by monotypy): Stomatia phymotis Helbling. Recent, Indo-Pacific. Stomatia cf. S. phymotis Helbling Plate 5, figure 19 Small, resembling a high-spired Haliotis; last whorl with double keel whose lower ridge bears prominent nodes; strong plicas present on body whorl immediately below suture. h/Ieasiireinents of the figured specimen, USNM 648272: width 8.5 mm, height 7.3 nnn. Occurrence: USGS 20534 on outskirts of Taguag near west coast of Guam; probably Alifan Limestone; age, Tertiary g or h. The single fossil is a mold showing the larger external markings. It seems closely related to, possibly identical with, the type S. phymotis, a variable and widely dis- tributed Recent Indo-Pacific species. The body whorl of the fossil does not descend as deeply as on the Recent shells. The Guam specimen appears to be the first fossil record of the genus. Genus SYNAPTOCOCHLEA Pilsbry Pilsbry, 1890, Manual Conchology, 12, p. 6, 25. Type (by original designation): Stomatella mon- trouzieri Pilsbry. Recent, New Caledonia. Synaptocochlea concinna (Gould) Plate 5, figures 20—23 Stomatella conciuna Gould, 1845, Boston Soc. Nat. History Proc., v. 2. p. 26. Adams. A.. 1854. in Thesaurus Conchyliornm, 2. p. 831, pl. 173. figs. 20, 21. Johnson, 1964, US. Natl. Mus. Bull. 239, p. 58, pl. 21, fig. 7. 42 Stomalclla (Synaptocochlea) concinna Gould, Pilsbry, 1890, Man— ual Conehology, v. 12, p. 28, p]. 2. figs. 6, 7; pl. 55, figs. 27, 28. Small, ovate, thin; body whorl large, aperture broadly oval; upper margin of outer lip turned down at junction with penultimate whorl. Sculpture consisting of fine spiral riblets, close set on most of shell but more Widely separated near aperture; riblets beaded by lines of growth; 011 upper and lower thirds of shell the ribs are intermittently dark red, the streaks being discernible in- side the aperture; on the middle (peripheral) third of the shell the ribs are uncolored. Measurements of the figured specimen, USNM 648273: diameter 2.7 mm. height 3.0 mm. The ornamentation and color pattern appear to dis— tinguish this small species from all others assigned to the genus. Occurrence: Figured specimen from drill hole F—1, Eniwetok Atoll, at a depth of 60—70 feet; three specimens in other drill holes even closer to surface; age, Recent; Recent shells were recovered from beach drift at Rongerik Atoll in the Marshall Islands. Gould’s types were col— lected in Hawaii, and the species has also been reported from the Tuamotu (Paumotul group. Synaptocochlea rosacea (Pease) Plate 5, figure 24 Gena rosacea Pease, 1867, Am. Jour. Conchology, v. 3, p. 284, pl. 24 [a] fig. 1. Pilsbry, 1890, Manual Conchology, v. 12, p. 41, pl. 55, fig. 12. Small, elongate-oval. moderately convex; spire pos— terior, whorls slightly angulated, body whorl flattened mud]. apex. 1"“th Shell marked by Close—set concentric Turbo delphinus Linnaeus, 1758, Systema naturae, 10th ed., p. 764. striae. which become less conspicuous near the-outer lip, and by fine lines of growth. Traces of irregular areas of brown are preserved on the body whorl. Measurements of the figured specimen (E41, 30—35 ft) I'SNM 648274: length 4.5 mm, breadth 3.0 mm, con- vexity 1.3 mm. Occm'rence: Two specimens from drill hole E—l, Eni- wetok Atoll, at a depth of 30—35 feet; age, probably Recent. Recent, from the Tuamotu [Paumotu] Islands. A minute shell from drill hole 28 on Bikini Atoll at a depth of 1,55541,566 feet (Tertiary f( probably represents this species. Pease described material Synaptocochlea lekalekana (Ladd) Plate 5, figures 25, 26 Simon [wirrrlelruhum Ladd, 1945. B. 1’. Bishop Mus. Bull. 18L ‘ p. 357, pl. 50, figs. 0, P. No additional material collected. Species based on four specimens collected from the Ndalithoni Limestone, CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS probably Pliocene (Tertiary h), Vanna Mbalavu (stas. 110B and 1100), Fiji. Synaptocochlea marshallensis Ladd, n. sp. Plate 5, figures 27, 28 Minute, ovate; spire low; aperture very large, wider than high, upper margin meeting penultimate whorl at midpoint; sculpture consisting of fine spiral ribs, cut by close-set axial lines. Measurements of the holotype (K—lB, 757—769 ft), USNM 648275: height 1.5 mm, diameter 2.3 mm. S. marshallensis is smaller and more strongly sculp- tured than S. lekalekana (Laddl from the Ndalithoni Limestone, probably Pliocene, of Vanua Mbalavu, Fiji. Occurrence: Two specimens from K—lB, Eniwetok Atoll, at depth of 757~769 feet; age, late Miocene (Ter- tiary gt. An incomplete specimen from E—l at depth of 870—880 feet (Tertiary f) probably represents the same species. Family ANGARIIDAE (DELPHINULIDAE) Genus ANGARIA Réding R6ding, 1798, Mus. Boltenianum, pt. 2, p. 71. Type (by subsequent. designation, Fischer, Species général et Iconographic des coquilles vivantes * * * p. 58, Paris, 1875): Turbo delphinus Linnaeus. Recent, Indo- Pacific; also reported from the upper Miocene of Java and Nias, the Pliocene and Pleistocene of Okinawa, and the Quaternary of Soemba. Angaria delphinus (Linnaeus) Plate 5, figures 29—34 Angnria delphinus R'oding, 1798, Mus. Boltenianum, pt. 2, p. 71. MacNeil, 1960, US. Geol. Survey, Prof. Paper 339, p. 29, pl. 16, figs. 6, 11—12. Dclphinula distorta (Linnaeus) Ladd, 1934, B. P. Bishop Mus. Bull. 119, p. 205—206, pl. 35, fig. 9. A reexamination of the two Fijian fossils described by Ladd in 1934 and an additional specimen collected from the same locality (USNM 648393) indicate that all fall within the range of the highly variable Recent type of the genus. The Fijian fossils are from the conglomerate at the base of the limestone section in the Miocene Suva Formation (Tertiary fl on Walu Bay, Viti Levu. On a single coarsely recrystallized specimen from ‘xuam, the surface plicae are poorly preserved but the general form and arrangement strongly suggest the type species. The specimen, USNM 648276, measures: height 30.2 mm, diameter 30.6 111111. It was collected from the Alifan Limestone (Tertiary g or h) at USGS locality 20720. PALEONTOLOGY Family TURBINIDAE Genus ASTRAEA Riiding R6ding, 1798, Mus. Boltenianum, pt. 2, p. 79. Type (by subsequent designation, Suter, 1913, Manual New Zealand Mollusca, p. 166) : Trochus imperialis Gmelin=T. heliotropium Martyn. Recent, New Zealand. Subgenus ASTRALIUM Link, 1807 Link, 1807, Besehreibung der Naturalien—Sammlung der Uni- versitat zu Rostock, p. 135. Type (by subsequent designation, Fischer, in Kiener, 1875, Spécies général et Iconographie des Coquilles vivantes, Genre Turbo, p. 51: Turbo calcar Linnaeus. Recent, Indo—Pacific. Astraea (Astralium) rhodostofna (Lamarck) Plate 6. figures 1—5 ’l'mchux r/wdostomus Lainarek, 1822, Hist. Nat. Aniinaux sans Vertebres, v. 7, p. 13. Aslralium (Cyclocnntha) pelmsum Martyn. Pilsbry, 1888, Manual Conchology, v. 10, p. 234, pl. 64, figs. 65, 66. Astralium petrusum Uirescens Pease, Ostergaard, 1935, B. P. Bishop Mus. Bull. 131, p. 17. Astraea (Calcar) confragosum Gould. Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 354. Troohus (Infundibulum) calcamlus Souverbie, Abrard, Annales de paléontologie. \'. 32. 48. pl. 4, fig. 9. 1946, Sculpture variable but characteristically having two distinct rows of peripheral spines, those in the upper row numbering about 12 on the body whorl, those of the lower row smaller and more numerous; the columella is wide, has a shallow groove, and bears a denticle near its base. Measurements of the figured specimen, USNM 648285: height 29.1 mm, diameter 25.3 mm. The best preserved of Ostergaard’s four Tongan fossils has many small subequal wrinkles, and the peripheral spines are not prominent. Occurrence: A common and widespread species; fossil occurrences from Saipan (figured specimen from USGS 21407; questionable specimen from USGS 17387); Guam (USGS 17416, 20574, 20616, 20634, 20636, 20732, 20981) ; Fiji (sta. 148, ()ngeal; Tonga (sta. 7, Tongatabu) ; New Hebrides (USGS 21028, Espiritu Santo and Eromanga) (Abrard) ; all occurrences in beds of post-Tertiary age. The Recent shells have been collected from many island groups in the Pacific, from the Marshall Islands to Fiji. Astraea (Astralium) aff. A. rhodostoma (Lamarck) Plate 6, figure 6 An external mold of an Astralium from the Main bor- ing at Funafuti Atoll has sculpture similar to the vari— able A. rhodostoma but probably represents a distinct 43 species. The shell had two rOWs of peripheral spines, but those in the lower row are twice as numerous as those in the upper; both rows are more oblique than in A. rho- dostoma, the spines of the lower row on the fossil making an angle of slightly less than 45° with the base. Measure- ments of the figured impression, USNM 648286: height 19.7 mm, diameter 18.7 mm. Occurrence: In core 528A (British Mus. Nat. History), dolomitic limestone from a depth of 1,006 feet, Main Boring, Funafuti Atoll; age, probably Pleistocene. Astraea (Astralium) eniwetokensis Ladd, n. sp. Plate 6, figures 7—9 Medium size, depressed conic; base slightly convex with narrow shallow umbilicus; whorls convex above, , concave below; body whorl with 15 prominent rounded nodes above periphery with lesser number of smaller nodes that end as open scaly processes; on body whorl rows of smaller nodes lie between two main series; base with nine concentric spinose ribs; columella with low obliquely pinched tubercle. Measurements of the holotype and only specimen, USNM 648290: height 7.9 mm, diameter 10.4 mm. Resembles A. calcar (Linnaeus), type of the subgenus, but has a lower spire. Occurrence: Drill hole F—l, Eniwetok Atoll, at depth of 790-800 feet; age, late Miocene (Tertiary g). Astraea (Astraliuni) waluensis Ladd, n. sp. Plate 6, figures 10—12 Astraea. (Calcar) sp. A, Ladd, 1934, B. P. Bishop Mus. Bull. 119, p. 205, pl. 35, figs. 7, 8. Shell medium in size, thick, trochoid; aperture ovoid, channeled at the periphery, nacreous within; columella wide with shallow depression and an elongate basal tooth; whorls flattened; body whorl with seven or eight broad-based spines lying well above the periphery; small oblique wrinkles cover the areas between the large spines; periphery marked by a row of small close-set spines; base flattened, bearing numerous concentric spinose ribs. Measurements of the holotype, USNM 648291: height 12.9 mm, diameter 10.8 mm. One of the two additional specimens representing this species has been designated the holotype. The form is closely related to the Recent A. rhodostoma Lamarek, but the fossils are smaller and less distinctly bicarinate. On the fossils the spines in the upper row are fewer and proportionately much larger. Occurrence: Five specimens from the Suva Formation, Viti Levu, Fiji (sta. 160); age, early Miocene (Tertiary f)- 44 Astraea (Astralium) sp. A Plate 6, figures 13—15 Medium in size, trochoid; whorls flattened; base gently convex near middle, concave near periphery and near middle, concave near periphery and near columella; nonumbilicate; body whorl with about 10 low spiral ribs that are beaded by oblique ribs; spiral ribs on lower half of whorls scaly, especially the marginal rib which is more prominent than those above; base with a dozen con- centric spinose ribs; aperture broken. Measurements of the figured specimen, USNM 648292: height (incompletel 11.2 mm, diameter (incomplete! 13.9 mm. Resembles Ash'uea cniwetokcnsis n. sp. from slightly younger beds in the same drill hole but has a sharper spire and finer sculpture. May represent an undescribed form, but the single specimen available is too incomplete to be made a type. Occurrence: Drill hole It], l‘lniwetok Atoll, at a depth of 8404850 feet; late Miocene (Tertiary g). Astraea (Astralium) sp. B Plate 6, figures 16—18 Small, troehoid; base flat and nonumbilicate; periphery earinate, extended into broad flattened regularly spaced spines, 10 being present on body whorl; whorls flattened above periphery, with 4 subequal beaded spiral ribs; base flat with 6 fine spiral ribs. Measurements of the figured specimen, USNM 648293: height 1.8 111111, diameter 2.1 mm. The single fossil appears to be immature; it has not been identified with a described species. Occurrence: Drill hole 2, Bikini Atoll, from core at a depth of 115 feet; age, Recent. Astrea (Astralium) sp. C Plate 6, figures 19—20 The opereula described below appear to belong to a species of Astralium, possibly to one of the two large shells, A. enz'u'etokensis and ‘4. sp. A, already described from the same Tertiary section in one of the drill holes that yielded some of the opercula. Each of the two shells recognized is represented by only a single specimen, and it is of course possible that still other species are com- pletely unrepresented in the drill—hole samples. There are a total of 19 specimens of the heavy opercula. These structures are nearly indestructible, and hence the high ratio of opercula to shells is understandable. The oper— cula show little variation and probably represent a single species. Operculum broadly ellipsoidal, heavy; inner face flattened with a rounded edge and a broad shallow spiral CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS ’ depression near the suture; nucleus below and to the left of the midpoint, the last whorl covering most of the inner face; outer face highly convex, broadly excavated near the margin except on the lower left side where the struc- ture thickens to a rounded apex; to the left of the apex and below the midpoint there is a shallow spiral depres— sion; surface more or less puckered by irregular shallow grooves. Measurements of the figured specimen (K—lB, 937—947 ft), USNM 648294: width 3.3 mm, height 2.8 mm. Occurrence: A total of 15 opercula were recovered from the 3 deep holes on Eniwetok Atoll at depths of 558—947 feet; four specimens were recovered from drill hole 2A on Bikini Atoll at depths of 925—1,063 feet. Age, late Ter- tiary (Tertiary fit at Eniwetok; f—g at Bikini}. A closely similar opereulum was recovered from the Suva Forma- tion on Viti Levu, Fiji (sta. FB—20) ; age, Miocene (Tertiary fl. Subgenus BELLASTRAEA Iredale Iredale, 1924, Linnean Soc. New South Wales Proc., v. 182, 232. 49, p. Type (by original designation): Bellastraea kesteveni Iredale (:Aslraea fimbrinta allot). Recent, Australia. Astraea (Bellastraea) sp. D Plate 6, figures 21—23 Minute, lenticular; apex flattened, periphery with prominent flattened spines, 11 on last whorl; umbilicus wide and deep, bordered by a broad beaded rib. Meas- urements of the figured specimen (K—»lB, Eniwctok, 841— 853 ft) USNM 648295: height 1.1 111111, diameter 2.9 mm. Occurrence: Figured specimen and six other examples from drill hole K—IB, Eniwetok Atoll, at depth of 841~ 853 feet in beds assigned to late Miocene (Tertiary 9); two additional specimens from same drill hole at depth of 863—873 feet, early Miocene (Tertiary fl; one speci- men from hole F—l, Eniwetok, at depth of 1,210-1,220 feet (Tertiary cl; a single specimen was found in drill hole 2A on Bikini Atoll at a depth of 1,030‘1,034 feet (Tertiary f). The 11 small fossils are probably im- mature. Astraea (Bellastraea) sp. E Plate 6, figures 24—26 Minute, planoconvex; spire depressed; periphery with a row of broad flattened upturned spines (nine on body whorl); suture impressed, scalloped near aperture by peripheral spines of preceding whorl; below periphery, whorl is semicircular in section with a low median ridge bearing prominent widely spaced, rounded knobs; this basal ridge spirals into the wide umbilicus as does an PALEONTOLOGY obscurely beaded rib bordering that structure; aperture subcircular. Measurements of the. figured specimen, USNM 648296: height 1.2 mm, diameter 3.2 111111. The aperture of the single small fossil is incomplete. It is possible that the shell is immature, but comparisons with large astraeids that have depressed early whorls do not support this possibility. The fossil probably repre- sents an undescribed species, possibly an undescribed subgcnns, but a new name must await better type mate- rial. The species differs markedly from Astrea sp. D that has been recovered from the same horizon on Eni- wetok. The form described as sp. E is flatter and has an impressed suture; it has fewer peripheral spines, and these are strongly upturned. The whorl is more convex below and bears a strongly beaded ridge. Occurrence: Drill hole K—lB on Eniwetok Atoll at. a depth of l,196—1,207 feet; from early Miocene tTertiary Cl. Subgenus VITIASTRAEA Ladd, n. subgen. Type: .lstraea (lr'itiastmea) holmesi Ladd, n. sp. Small; spire low; early whorls with a nodose keel or shoulder from the base of which a flat scalloped fringe spreads outward to conceal the suture; shoulder becomes obsolete on the body whorl and below it the scalloped fringe changes into a peripheral keel which, in turn, dies out before reaching the aperture; a third keel appears on the body whorl below the peripheral keel; it descends below the periphery and dies out before reaching the aperture. Aperture circular; umbilicus narrow, sur— rounded by a coarsely puckered rib. The scalloped fringe that overlaps the suture on the early whorls indicates clearly that A. holmesi is an astraeid, but the pattern set by the other disappearing keels is not to be matched closely in any of the numerous subgenera of Astraea. The closest approach seems to be in ()rlaastralium Sacco, known from the Miocene and l’liocene of Europe. In that group there is a spiny peripheral keel that, on the early whorls. covers the suture. Later whorls also have two other 111ajor keels, one above and one below the periphery. Both of these are armed with blunt knobs. None of the keels dies out before reaching the aperture. and the shell is imperforate. Astraea (Vitiastraea) holmesi Ladd, n. sp. Plate 6. figures 27—29 Small, low spired; apex flat; . early whorls with a strong nodose keel or shoulder from the base of which a thin flat scalloped fringe extends outward to conceal the suture completely; shoulder dies out on body whorl and scalloped fringe changes to a sharp peripheral keel which 45 also dies out before reaching aperture, a third spiral keel astrong and beaded—appears below the periphery on the body whorl; it descends gradually and dies out before reaching aperture. Aperture circular, outer lip thin, inner lip callused and broadly expanded below; umbili- cus narrow, surrounded by a coarsely puckered rib. Measurements of the holotype, USNM 648297: height 2.4 111111, diameter 3.0 mln. Occurrence: Holotype and only specimen from the Miocene (Tertiary f) Suva Formation on Viti Levu, Fiji tsta. 160). Genus ARENE H. and A. Adams H. and A. Adams, 1854, Genera Recent Mollusca, v. 1, p. 404. Type «by subsequent designation, Woodring, 1928, Carnegie Inst. Washington Pub. 385, p. 422): Turbo cruentatus Megerle von Miihlfeld. Recent, West Indies. Arene (Arene) metaltilana Ladd, n. sp. Plate 7, figures 1—6 Minute, strongly turreted; apex flattened; a smooth gently convex whorl of protoconch followed by 21/2 sculp- tured whorls; aperture subcircular, inner lip expanded below; umbilicus moderately wide and deep. Sculpture consisting of three spiral ribs that form a flattened peripheral band on the body whorl; uppermost rib strongest, turned upward and scalloped into rounded scales that are most prominent on the earlier whorls; middle peripheral rib smaller than other two; flattened areas above and below peripheral band bear obscure axials; a broad puckered rib spirals into the umbilicus. Measurements of the holotype, USNM 648298: height 1.2 111111, diameter 1.3 111111. Paratype, USNM 648299: height 1.2 111111, diameter 1.6 111111. A. metaltilana is characterized particularly by the comparatively smooth flattened areas that lie above and below the strongly ribbed peripheral band. Occurrence: Represented by only two shells, both from drill hole 2B on Bikini Atoll; holotype from a depth of 1,702~1,713 feet and paratypc from a depth of 2,297— 2,307 feet; age. early Miocene (Tertiary e). Arene (Arene) sp. A Plate 7, figures 7, 8 Very small; spire moderately high, turreted; apex de— pressed; about four whorls, flattened above a prominent shoulder; aperture subcircular; umbilicus narrow and deep, bordered by a heavy spiral. Sculpture consisting of three strong spiral ribs that form a flattened peripheral band on the body whorl; on earlier whorls the upper two of the primary whorls are conspicuously scalloped; three secondary spirals are present on the body whorl above 46 the peripheral band and others occur on the base; still finer spirals occur between the primary spirals; close-set . oblique axials, present over the entire shell, cause bead- ing of the secondary spirals and a puckering of the umbilical rib. Measurements of the figured specimen, USNM 648300: height 2.3 nnn, diameter (incomplete) 2.6 mm. The species is represented by a single specimen on which the peristome is not preserved. There seems little question about the generic reference, but I have not found a clOse living relative in the Pacific. The fossil is similar in many ways to 4-1. mineata Dall, a Recent species from Santo Domingo and other parts of the Caribbean, but it has a more depressed apex, a more prominent peripheral band, and more conspicuously scalloped early whorls. ()ccwrencc: Drill hole 2A, Bikini Atoll, at a depth of 742—747 feet; age, late Miocene (Tertiary g). Genus LIOTINA Munier-Chalmas (in P. Fischer) Munier-Chalmas in Fischer, P., 1885, Manual Conchology, p. 831. Type Cossman, 1888, Catalogue Illustre Coquilles Fossiles * * *, v. 3, p. 53): Delphinula gereillei Defrance. Middle Eocene, France. (by subsequent designation) Subgenus AUSTROLIOTIA Cotton Cotton, 1948, Royal Soc. South Australia Trans, 72, p. 31. Type (by original designationl: LL‘0t/a botanica Hed- ley. Recent, New South Wales. Liotina (Austroliotia) cf. L. botanica (Hadley) Plate 7, figures 9—11 Small, lenticular. solid; about four whorls, gently con- vex above a weak shoulder, strongly and uniformly convex below; suture impressed; aperture circular and slightly oblique; peristome complete, outer lip thickened below shoulder to form a varixlike structure leading to a thick pad of callus that projects over part of the wide umbilicus. Sculpture consisting of 10 spiral ribs; the 3 that lie above the shoulder are weak, the others, includ— ing 1 that spirals into the umbilicus, are strong; spirals crossed by axial ribs, about 20 on body whorl, giving the shell a latticed appearance. Measurements of the figured specimen, USNM 648301: height 1.4 111111, maximum diameter 3.3 mm, minimum diameter 2.3 mm. The single fossil is somewhat worn but seems to agree in all essential features with the larger L. botanica (Hedley, 1915, p. 710), type species of Austroliotia. Occurrence: In drill hole F—4—A, Elugelab Island,‘ Eniwetok Atoll, at a depth of 6—12 feet; age, Recent. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Subgenus DENTARENE Iredale Iredale, 1929, Queensland Mus. Mem., V. 9, p. 274. Type (by original designation): Denta'rene sarcina Iredale, new name for Delphinula crenata Kiener. Re- cent, Philippines. Liotina (Dentarene) loculosa (Gould) Plate 7, figures 12—14 Lioliu loculosa Gould, 1862, Otia Conchologica, p. 114. Johnson, 1964, U.S. Natl. Mus. Bull. 239, p. 103, pl. 5, fig. 15 above [not fig. 12]. Liulina cycloma Tomlin, 1918, Jour. Conchology, v. 15, no. 10, p. 305, pl. 10, figs. 1, 2. Liotina (Dentarcne) loculosa (Gould), Kuroda, 1960. Catalogue of mollusean fauna of Okinawa Islands, p. 5. Medium in size, heavy, discoidal; spire low, body whorl descending to a circular aperture surrounded by a strong erect varix; umbilicus narrow and deep, with a ridge that merges with the varix surrounding the lip. Whorls of protoconch smooth, remainder of shell covered by fine chise-set axial lamellae. Six spiral cords recog- nizable on. the body whorl; the smallest of these, next to the suture, bears regularly spaced spiny elevations; a second cord, somewhat larger, forms a low shoulder and bears similar spiny elevations; two very strong cords form the periphery and their prominent spines are con- nected by the bundles of axial lamellac that form the spines; a fifth cord near the middle of the base is com- parable in size to the cord at the shoulder; a sixth cord that encircles the umbilicus is deeply notched like a cog wheel. Measurements of the figured specimen (E—l, Eni— wetok, 110420 ft) USNM 648302: height 3.6 mm, diameter 5.1 mm. L. loculosa is similar to L. crenata (Kiener), type of the subgenus Dentarene, but that of Recent species, re- ported from the Philippines, Australia, and Ceylon, has a smooth base. L. infensa Finlay, a Recent Australian species, has wide umbilicus. L. chinenensis described by MacNeil (1960, p. 29, pl. 11, figs, 29—31) from the Pliocene of Okinawa is a larger. and preportionately higher form with a wide umbilicus and fewer peripheral spines. Occurrence: Rare examples, total of seven specimens, in four drill holes on Eniwetok Atoll at depths of 2—120 feet; all Eniwetok occurrences probably Recent. Com— mon in beach drift at Rongerik Atoll; a single shell found at Bikini. The type, at Recent shell, was collected in the Ryukyu Islands. A single specimen from hole 2 on Bikini at depth of 86—87 feet is probably Recent; a worn speci- men in the same hole from a depth of 1,366—1,377 feet (Tertiary 6) may have been derived from a higher level. PALEONTOLOGY Liotina (Dentarene) sp. A Plate 7, figures 15—17 Medium in size; spire depressed, suture impressed; umbilicus moderately wide, deep. Whorls of protoconch smooth, remainder of shell covered by fine close—set axial lamellae. Six spiral cords recognizable on the body whorl: the uppermost of these is broad and low, lying about one-third of the distance from suture to periphery; the peripheral cord is the strongest and is extended into sharp spiny processes that give the shell 21 stellate appear- ance when viewed from above or below; four cords with low regularly spaced spiny projections occur below the periphery, the lowest closely encircling the umbilicus; spiny projections on basal cords merge to form distinct axial ribs. Measurements of the figured specimen (E—l, 2,590— 2,600 ft), USNM 648303: diameter (incomplete) 3.4 mm, height (incomplete) 1.9 mm. Liotfna sp. A is clearly distinct from L. loculosa Gould found in Recent beds at. higher levels in Eniwetok drill holes. The Miocene shells have a lower spire, a wider umbilicus, and a single prominent peripheral cord; like— wise, on the Tertiary shells the axial ribs below the periphery are much more conspicuous than on L. loculasa. The Miocene shells clearly represent an undescribed species but, because none of the available specimens has the aperture preserved, a specific name is withheld. Occurrence: Five specimens from drill holes E-1 and K~1B on Eniwetok Atoll at. a depth of 936—2,600 feet; age, early Miocene (Tertiary e and f). Liotina‘ (Dentarene) sp. B Plate 7, figures 18—20 A single incomplete specimen (USNM 648304,) from a drill hole on Bikini Atoll closely resembles Liotina sp. A from Eniwetok but has more numerous cords on the body whorleithree above the peripheral cord and four below —and lacks well-developed axial ribs on the base. The Bikini shell may represent a distinct species, but the single specimen does not show the apertural features and has, therefore, not been given a specific name. Measure- ments: diameter (incomplete) 2.2 mm, height (incom— plete) 1.4 mm. Occurrence: Drill hole 2B, Bikini Atoll, at a depth of 1,629—1,639 feet in beds referred to early Miocene (Ter- tiary f). Genus TURBO Linnaeus Linnaeus, 1758, Systema naturae, 10th ed., p. 761. Subgenus TURBO s.s. Type (by subsequent designation, Montfort, 1810, Conehyliologic systématique, v. 2, p. 203): Turbo 47 patholafus Linnaeus. Recent, Indo-Paeific; also reported from upper Miocene and Pliocene of Java, the Pliocene and Quaternary of Timor and Okinawa, the Pliocene of Taiwan, the Quaternary of Celebes, and the Pleist- ocene(?) of Tonga. Turbo (Turbo) petholatus Linnaeus Plate 7, figures 21, 22 Turbo petholatus Linnaeus, 1758, Systema naturae, 10th ed., p. 762. Reeve, 1848, Conchologica Iconica, v. 4, Turbo: pl. 3, fig. 12. Sowerby, 1886, Thésaurus Conchyliorum Turbo, p. 191, pl. 40, fig. 46. Pilsbry, 1888, Manual Conchology, v. 10: p. 193, pl. 40, fig. 14. Ostergaard, 1935, B. P. Bishop Mus. Bull. 131, p. 48. Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 354. MacNeil, 1960, US. Geol. Survey Prof. Paper 339, p. 31, pl. 18, fig. 12. Shell medium in size, turbinate, imperforate, solid; aperture circular, outer lip thin, inner lip callused; sculp- ture consisting of inconspicuous axial lines of growth. Measurements of the figured specimens from Guam: (USGS 20653), USNM 648277: height (incomplete) 23.8 mm, diameter 23.8 mm; (USGS 20720), USNM 648278: height 294 mm, diameter 27.9 mm. Occurrence: On Guam, single specimens from half a dozen localities in the reef facies and Agana Argillaceous Member of the post-Miocene ,Mariana Limestone and from beds that probably belong to the late Tertiary Alifan Limestone (Tertiary g or h). Previously described (single specimen) from the Futuna Formation, early Miocene (Tertiary f) from Lakemba in eastern Fiji, the upper Miocene and Pliocene of Java. Common in post- Tertiary beds in the New Hebrides (USGS 21028, Espiritu Santo). Recent shells have been collected from many parts of the Indo—Pacific region. Turbo (Turbo) petholatus thanus Ladd Plate 7, figure 23 Turbo (Turbo) petholatus thauus Ladd, 1934, B. P. Bishop Mus. Bull. 119, p. 203, pl. 35, fig. 3. Four additional specimens have been collected from the type locality in Suva, Fiji—one juvenile and three adults. The color pattern, though faded, is recognizable as a series of revolving broken lines of dark spots and irregular areas, basically similar to thOse exhibited by living examples of T. petholatus. Measurements of the figured specimen (Viti Levu, Fiji, sta. 160) USNM 648279: height 23.2 mm, diameter (incomplete) 23.2 mm. Occurrence: Five specimens from station 160, Walu Bay, Suva, Fiji; age, Miocene (Tertiary f), Suva For- mation. Two small specimens that apparently represent 48 this subspecies were collected from the Ndalithoni Lime- stone on Vanua Mbalavu in eastern Fiji (sta. 1100); age, probably Pliocene (Tertiary h). A dozen heavy opercula, apparently referable to this species, were collected with the shells at stations 160, 160A, FB—20. Subgenus MARMAROSTOMA Swainson Swainson, 1829, Zool. Illus., 2d ser., v. 1, pl. 14. Type (by original designation): Turbo chrysostomus Linnaeus. Recent, Pacific islands. Turbo (Marmarostoma) chrysostomus Linnaeus Plate 7, figure 24 Turbo (‘fll’j/NUA‘IUIIIJIN Linnaeus. 1758, Syslcma nalurae. 10”] ed., p. 762. .llurmm‘usl(mm ('Iu'gms/mmzs Linnaeus. Illus., 2d set, V. 1, pl. 14. Turbo (Turbo) eln'ysoslmnus Linnaeus, Pilsbry, 1888. Manual Conchology, v. 10, p. 200, pl. 40, fig. 19. Swainson. 1829, Zool. A dozen specimens referable to this spirally ribbed and variable species were collected from several localities on Guam and one from the New Hebrides. Shells from both areas are strongly shouldered, the central part of each whorl being conspicuously flattened with strong scaly ribs at the top and bottom of the flattened band; ribs of two or three sizes alternate; on well-preserved specimens the scales on the main ribs are prominent open nodes. Measurements of the figured specimen from Guam, [’SNM 648280: height 22.0 mm, diameter 22.9 111111. Occurrence: Guam at USGS localities 20636 (figured specimen), 20533, 20732, and 21377 (all from the Agana Argillaeeous Member of the Pliocene and Pleistocene Mariana Limestone); single incomplete specimen from New Hebrides, USGS 21028 in beds believed to be no older than Pleistocene. Recent shells have been collected in many island groups in the southwest Pacific. Turbo (Marmarostoma) argyrostomus Linnaeus Plate 7, figures 25, 26 Turbo argyrostomus Linnaeus, 1758, System-a naturae, 10th ed., p. 764. Reeve, 1848, Conchologica Iconica, v. 4, pl. 2, fig. 7. Pilsbry, 1888, Manual Conehology, v. 10, p. 197—198, pl. 40, fig. 18; pl. 42, fig. 41; pl. 46, fig. 8. Ostergaard, 1935, B. P. Bishop Mus. Bull. 131, p. 47. Demond, 1957, Pacific Sci., v. 11, p. 268—269. .llm‘marosloma argyrostoma (Linnaeus), MaeNeil, US. Geo]. Survey Prof. Paper 339, p. 31, pl. 18. fig. 4. This species seems to be the most abundant of several large strongly ribbed turbos that are widely distributed in the island area today, and the fossil collections suggest that this species was also most abundant in Pleistocene CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS time. Plate 7, figure 25, shows a specimen with heavy operculum in place. Measurements of the figured specimens: (1) specimen from Saipan (USGS 17387), USNM 648281; height (tip of spire broken) 59.5 mm, diameter 54.5 mm; (2) speci- men from Guam, (USGS 20679) USNM 648282; height (spire incomplete) 62.6 mm, diameter 55.1 mm. T. argyrostomus is closely related to T. setosus Gmclin, which is a species that has been reported over much of the same range although in less abundance. The two species show a distinct tendency to intergrade. End members of the two series exhibit four rather striking differences: T. argyrostonms has a strong shoulder, its ribs are spinose, it is distinctly umbilicate, and the inner side of its, heavy operculum is flat or slightly convex. T. sofas-us shows no shoulder, its ribs are smooth except for growth lines, it is nonumbilicate, and the inner side of its operculum is distinctly concave. However, in a large series of Recent shells of T. argyrostomus there is a considerable variation in the development of the shoulder, the spines, and the umbilicus. The inner face of the operculum seems a constant character, but unfor- tunately one that can only rarely be used in studying fossils. At Funafuti, Hedley (1899a, p. 408) found T. argyrostomus on the west (lee) side of the atoll and T. setosus on the east (windward) side. Occurrence: One of the commonest species in the Pliocene and Pleistocene Mariana Limestone of Guam, in the Pleistocene Tanapag Limestone of Saipan, and in limestones of Quaternary age in the New Hebrides and Tonga; an immature but typical specimen recovered from drill hole MU—5 on the island of Mujinkarikku, Eniwetok Atoll, at a depth of 18~211/2 feet is Recent in age. An immature shell from a depth of 680—690 feet in drill hole F—1 on Eniwetok seems to represent this vari— able species. Though still preserving traces of the origi- nal color pattern on the spire, the single shell shows evidence of wear. The beds from which it is recorded are referred to the late Miocene (Tertiary 9); it may have been derived from a higher horizon. Opercula that probably represent this species were recovered from three drill holes on Eniwetok at depths of 66—340 feet and molds from drill hole on Funafuti at depths of 922— 1,053 feet; age, post-Miocene. The species has been described from the Pliocene and Pleistocene of Okinawa. Living examples have been col- lected from many parts of the Indo-Pacific, from Aldabra Island in the western Indian Ocean through Indonesia to Australia, and the Pacific islands from Japan to the Tuamotus. It lives along the seaward reef edge, on the reef flats, and on lagoonal reefs. PALEONTOLOGY Turbo (Marmarostoma) setosus Gmelin? Plate 7, figure 27 Turbo sews-us Gmelin, 1791, Systema naturae, 13th ed., p. 3494. Reeve, 1848, Conchologica Iconica, v. 4, pl. 8, fig. 37. Pilsbry, 1888, Manual Conchology, v. 10, p. 195, pl. 63, fig. 32. Demond, 1957, Pacific Sci., V. 11, p. 387. An incomplete mold from core piece 276 obtained at Funafuti in the Ellice Islands at a depth of 526-546 feet very probably represents this species. There is no indication of a shoulder nor of spines on the ribs such as characterize T. argyrostomus Linnaeus, described above; the broad ribs are wider than the interspaces, and sec- ondary ribs are present. Figured specimen USNM 648283 is a cast whose height is 24 mm; it was taken from a core loaned by the British Museum; age post- Miocene. An incomplete and poorly preserved specimen from the post-Miocene Mariana Limestone of Guam (USGS 21373) may possibly represent the same species. T. setosus has been reported from many island groups in the western Pacific. Hedley (1899a, p. 408) found it abundantly on the east side of Funafuti at low water on the outer reef. Turbo (Marmarostoma) crassus Wood Plate 8, figures 1, 2 Turbo crassus Wood, 1828, Index Testaceologicus supp.. pl. 6, fig. 43. Reeve, 1848, Conchologica Iconica, v. 4, fig. 10. Pilsbry, 1888, Manual Conchology v. 10, p. 194, pl. 47, fig. 20. Ostergaard, 1935, B. P. Bishop Mus. Bull. 131, p. 48. Turbo canaliculatus Reeve, 1848, Conchologica Iconica, v. 4, fig. 27. Shell large and heavy with broad flat spiral ridges separated by narrow shallow grooves: On many shells there is a strong spiral keel on the upper part of the whorl; above the keel the surface is deeply concave, be- low the keel a similar concavity, if present, is shallow. On the fossil specimens from Tonga, identified as this species by Ostergaard, the keel is present but not strongly developed. Measurements of the figured specimen, B. P. Bishop Museum, 202976: height 79.3 mm, diameter 63.3 mm. Occurrence: Two specimens from limestone near Houma Village, Tongatabu, Tonga at an altitude of 35 feet; probably Pleistocene. Ostergaard also collected the species alive on a wave bench at the foot of a sea cliff below the fossil locality. I found it rare on the reefs on both sides of the entrance to Suva harbor, Fiji. Re- cent shells have also been collected from Samoa, the Admiralty and Solomon Islands, New Caledonia, and northern Australia. 49 Turbo (Marmarostoma) perlatus Abrard Turbo (Senectus) perlatus Abrard, 1946, Annales de paléontologie, v. 32, p. 50, pl. 4,‘ fig. 11. As pointed out by the author of the species, T. perlatus is closely related to T. chrysostomus Linnaeus and T. radiatus Gmelin, differing from these by having well- developed beads on the spiral cords. The beads are not cut by the axial lamellae and are particularly conspicuous on the lower parts of the whorls and on the base. Some Recent shells of T. chrysostomus from New Caledonia, Palau, and the Philippines show a moderate develop- ment of beading on the lower spiral cords, but in no specimen was this feature as strongly marked as in T. perlatus. The type, from the upper Miocene of Epi, New Hebrides, is probably a young shell. The species has not been found in the Miocene or in younger beds elsewhere in the islands. Turbo (Marmarostoma) sp. A Plate 8, figures 3, 4 Turbo sp. a Mansfield, 1926, Carnegie Inst. Washington,Pub. 344, p. 88, pl. 3, fig. 2. Turbo sp. b Mansfield, 1926, Carnegie Inst. Washington Pub. 344, p. 88, pl. 3, fig. 3a, 3b. . Turbo (Ocana) cf. gruneri Philippi, Ladd, 1935, B. P. Bishop Mus. Bull. 119, p. 204, pl. 35, figs. 4, 5. Examination of additional material has shown that this strongly ribbed form should be placed in M armaro- stoma. On the middle and upper parts of the whorls, large ribs alternate with small ribs, and on the base, the ribs are subequal in size. All ribs are beaded, those on the base and the upper parts of the whorls most con- spicuously so. Occurrence: Numerous molds from stations 160, 295 (figured specimen, B. P. Bishop Mus, geology No. 1228), and 297, Viti Levu, Fiji; age, probably early Miocene (Tertiary f). Genus CYNISCA H. and A. Adams H. and A. Adams, 1854, Genera Recent Mollusca, v. 1, p. 406. Type (by original designation): 0. granulata A. Adams=Delphinula granulosa [Dunker ms.] Krauss. Recent, off South Africa. Cynisca pacifica Ladd, n. sp. Plate 8, figures 5—7 Small, depressed-turbinate, thick; sutures channeled; umbilicus moderately wide, deep; aperture circular, faintly lirate within; upper edge of outer lip extended onto base of penultimate whorl. Sculpture consisting of strong spiral ribs all of which are made granulose by 50 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS axial lines; the peripheral rib and the three above it are larger than the five ribs on the base; of the basal ribs the two next to the umbilicus are more strongly beaded than the others. Measurements of the holotype, only specimen, USNM 648284: height 4.1 mm, diameter 4.5 mm. The Miocene shell from Eniwetok appears to be the only known fossil occurrence. At least six species have been referred to Cynisca and all were collected from the seas off South Africa—the extreme western edge of the Indo-Pacific region. C. pacifica is very closely related to the type C. granulosa and to four other species, the chief differences being in sculpture. C. pacifica has fewer ribs than the type C. granulosa Krauss; the bead- ing of the ribs is not restricted to the upper ribs as in that species, and the apertural lirae are less well devel- oped. C. pacified appears to be most closely related to C. forticostata Smith, but that species has only seven spiral ribs. The three species named by Bartsch (1915, p. 163—166)——C. gloriosa, C. alfredensis, and C. afrz'cana —are based on worn beach shells, and the apertural features are obscure or wanting. C. gloriosa bears 11 ribs, C. alfrerlensis 7 ribs, and C. africana 8 ribs. On none of these three species is the beading developed on all ribs as in C. pacifica. Occurrence: Drill hole-E-l on Eniwetok at a depth of 1,000—1,010 feet; age early Miocene (Tertiary f). Genus LEPTOTHYRA Pease Pease, 1869, Am. Jour. Conchology, v. 5, p. 70. Type (by monotypy). Leptothyra costata Pease. Re- cent, Hawaii. Leptothyra maculosa (Pease) Plate 8. figures 8—13 Collonia maculosa Pease, 1868, Am. Jour. ‘Conchology, v. 4, p. 91, pl. 11, fig. 1. Leptothyra maculosa (Pcase), Pilsbry, 1888, Manual Conchology 10, p. 256,. pl. 57, fig. 60. Shell minute, nacreous within; apex blunt, umbilicus narrow, aperture circular; edge of outer lip thin, basal edge of inner lip reflected outward; sculpture consisting of three strong primary spiral ribs, with secondary spirals between and below; uppermost of primary spirals, spiral nearest the suture, and one next to umbilicus beaded. Each of the primary ribs, and in some specimens, the basal ribs, spotted at regular intervals with reddish brown. Measurements of the figured specimen (E—l, Eniwetok, 40—45 ft), USNM 648305: height 1.7 mm, diameter 1.6 mm. Occurrence: The species is common in the post-Mio- cene parts of several holes on Eniwetok and Bikini Atolls. The shells are so characteristically marked that well-preserved specimens may be recognized with ease. The globular shells are so small and so light that they circulate freely in drilling mud, and occurrences of White glistening shells among buff—colored Tertiary fossils are not to be trusted. Some of the fossil occurrences, however, are preserved as are other Tertiary shells, and there is no reason to question the depths. A few of these fossils retain faint traces of original color. Unquestioned fossils were found in beds referred to Tertiary f and g, the maximum depth being 830—842 feet in hole K—IB on Eniwetok. The species also is abundant in the Miocene Suva Formation (Tertiary f) on Viti Levu (sta. 160). The Fijian shells are somewhat larger than those from the Marshall Islands and are badly worn, but there is little doubt that they represent the same species. Rare specimens were also found in the limestone of Tongatabu, Tonga (B. P. Bishop Mus, cat. 202980; sta. 3), prob- ably Pleistocene, and in the Recent sediments drilled on Funafuti at depths of 65 and 70 feet. The Recent shell was originally described from the Tuamotu [Paumotu] Islands. It has also been collected in Hawaii and is common in the northern Marshalls. Leptothyra inepta (Gould) Plate 8, figures 14—22 Monilm [ncplu Gould. 1861. Boston Soc. Nat. History Proc, v. 8, p. 16. Pilsbry, 1889, Manual Conehology, v. 11, p. 254. Johnson, 1964, US. Nat]. Mus. Bull. 239, p. 91, pl. 4, fig. 2. Minute, turreted; apex flattened or slightly depressed. Body whorl divided into three subequal parts by two spiral angulations; uppermost part flattened, middle section (between two angulations) gently convex, lowest part (base) convex. Suture impressed, aperture sub- circular, outer lip thin, inner lip callused and extended below; umbilicus moderately wide, plicate. Sculpture consisting of about 20 strong spiral ribs, those at the angulations being larger than the others, except the rib encircling the umbilicus Which is large and coarsely beaded; ribs on penultimate whorl beaded; on the base, small secondary ribs developed between some of the pri- mary ribs. On the holotype (USNM 1372), axial bands of reddish brown cross the upper part of the whorls and near the aperture there are larger areas of pink; several of the fossils preserve remnants of this color pattern. Measurements of the figured specimen (Mu—4; Eni- wetok, 401/2—41 ft), USNM 648306: height 2.8 mm, diameter 2.8 mm. Gould’s type, USNM 1372 (pl. 8, figs. 19—22) measures: height 2.3 mm, diameter 2.5 mm. The two angulations that enclose a nearly flat periph- eral area particularly characterize this species. PALEONTOLOGY 5 1 Occurrence: Nine specimens from several drill holes at depths above 80 feet on Eniwetok Atoll; age, Recent. Gould’s Recent type was collected at Kagoshima, Japan, in sand under 5 feet of water. Leptothyra harlani Ladd, n. sp. Plate 9, figures 1—3 Minute; spire low, turreted; apex depressed; body whorl with inconspicuous shoulder; suture impressed; aperture subcircular, outer lip thin, callus of inner lip extended below; umbilicus wide and deep. Sculpture con- sisting of spiral ribs of which three or four near the periphery are a little larger than the others; above and below peripheral zone, ribs beaded by axial striae; a coarse puckered rib surrounds the umbilicus. Well-pre- served specimens retain traces of broad axial bands of brown color. Measurements of the holotype (K—lB, Eniwetok, 663-674 ft), USNM 648307: height 1.9 mm, diameter 2.5 mm. Resembles L. inepta but has a lower spire, is less strongly shouldered, and is less flattened around the periphery. Occurrence: Eight specimens from drill holes E—l and K—lB on Eniwetok Atoll at depths of 642—950 feet; age, Miocene (Tertiary f—g). A single specimen from drill hole 2B on Bikini at depth of 820—831 feet (Tertiary 9) may represent the same species. Leptothyra aft. L. laeta Montrouzier Plate 9, figures 4—6 Small, slightly turreted; apex flattened, shell thick; body whorl with inconspicuous shoulder; outer lip thick- ened inside, its upper edge descending sharply at the aperture; suture impressed; aperture subcircular, strongly oblique; inner lip thickened below at termination of wide puckered rib surrounding the deep umbilicus. Sculpture consisting of numerous spiral ribs; near the periphery large ribs alternate with smaller ones; above the shoulder on early whorls the ribs are conspicuously beaded; ribs on base weakly beaded. Holotype and one other specimen retain faint traces of axial bands of brown color. Measurements of the figured specimen (K—lB, Eni- wetok, 957—968 ft), USNM 648312: height 2.9 mm, diameter 3.2 mm. The four fossil specimens differ from Recent examples of L. laeta by having an inconspicuous shoulder; they are smaller than the Recent shells and may be imma- ture; this would account for the fact that the columella is not excavated next to the umbilicus and for the ab- sence of well-developed crenulations within the aperture. L. laeta has been reported from Australia, New Cale- donia, Fiji, and the Solomon Islands (Pilsbry, 1888, p. 258); Hedley (1899a, p. 408) found the shells common on the lagoon beach at Funafuti. Occurrence: Four specimens from drill holes E—l and K—1B on Eniwetok Atoll at depths of 957—1,985 feet; age, early Miocene (Tertiary e—f); a single specimen from hole 2B on Bikini at 1,902—1,913 feet (Tertiary e) may represent the same species. Leptothyra afi. L. candida (Pease) Plate 9, figures 7—9 Minute, globose; whorls inflated; suture impressed, descending slightly at aperture; aperture circular, outer lip thin, inner lip expanded below; umbilicus narrow, plicate. Sculpture consisting of about 10 spiral ribs, 4 of which on the broad periphery are larger than the others; fine secondary ribs are discernible under magni- fication; ribs near the suture and those on the base are beaded. Measurements of the figured specimen (drill hole BO— 2—1, depth 7 inches), USNM 648308: height 1.7 mm, diameter 2.2 mm. L. aff. candida appears to be characterized particu- larly by the uniform rate of curvature of its inflated whorls and the absence of a shoulder or strong peripheral rib. The ribs of the specimens from Eniwetok are more conspicuously beaded than ribs of shells from Hawaii. Occurrence: Two specimens from Eniwetok Atoll: in drill hole BO—2—1 on island of Bogallua, at a depth of only 7 inches and in drill hole E—l, Parry Island at depth of 40—45 feet; age, Recent. The Eniwetok speci- mens appear to be closely related to L. candida from Hawaii, the area from which the shells described by Peasc (1860, p. 436, as Collonia? candida) were obtained. tained. Leptothyra balnearii Pilsbry Plate 9, figures 10—12 Leptothyra balnearii Pilsbry, 1920, Acad. Nat. Sci. Philadelphia Proc., v. 72, p. 378, fig. 14. Minute, globose, wider than high; apex flattened, per- forate, thick; aperture oblique, outer lip thin, inner lip expanded below. Sculpture consisting of smooth spiral ribs of which three or four on the gently rounded periph- ery are larger than the others; above there is a single beaded rib and, next to the suture, a wide beaded band; on the base three or four slightly beaded riblets and a larger beaded rib spirals into the umbilicus. On some shells, secondary threads are developed between the peripheral ribs. Well-preserved fossil specimens, like some 52 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Recent shells, are red except for the first whorl and the umbilical area, which are colorless. Two older fossils retain traces of brown spots on the peripheral ribs of the body whorl, a pattern likewise found on the shells of living specimens. Measurements of the figured specimen (drill hole F—l, Eniwetok Atoll, depth 55—60 ft), USNM 648309: height 0.7 mm, diameter 1.0 mm. Occurrence: Represented by a total of seven specimens from five drill holes on Eniwetok Atoll. Five specimens from depths of 20—70 feet are Recent; one from a depth of 620—630 feet is late Miocene (Tertiary g); the oldest from a depth of 904—916 feet is early Miocene (Ter- tiary f). Pilsbry’s types were collected in Hawaii, off Waikiki at a depth of 25—50 fathoms. Shells have also been col- lected at other localities on Oahu and on Molokai and Kauai. The Marshall Island fossils are smaller than the Hawaiian shells but appear identical in all other fea— tures. The species is similar to the type species L. costata Pease, a Recent species from Hawaii that has a different color pattern; L. cotata also differs by having a thicker outer lip. Leptothyra wellsi Ladd, n. sp. Plate 9, figures 13—15 Minute; spire flat or nearly so, umbilicus wide and deep; aperture oblique, outer lip thin, inner lip expanded below. Sculpture consisting of three or four smooth spiral ribs in the peripheral zone and smaller beaded ribs im- mediately above and below; a large rib that borders the umbilicus and two others that spiral into it are con- spicuously beaded. The holotype, paratype B, and sev- eral other well-preserved specimens retain traces of radial brown bands on the crests of the ribs. Measurements of the types: Holotype (F—l, Eniwetok, 690—700 ft), USNM 648310: height 0.9 mm, diameter 1.2 mm; paratype A (E—1, Eniwetok, 770—780 ft), USNM 648311, and paratype B (Viti Levu, Fiji, sta. 160), USNM 648406 have the same measurements as the holotype. L. wellsi resembles L. balnearii that occurs most com- monly in younger beds but has a lower spire and a much wider umbilicus. In two samples in which the species occur together they can be differentiated without difli- culty. Occurrence: More than 50 specimens from 30 levels in 3 drill holes on Eniwetok Atoll at a depth of 230— 1,993 feet; 3 specimens from 2 deep holes on Bikini Atoll at depth of 862—884 feet; abundant in the Suva Formation at station 160 on Viti Levu, Fiji. Age, Re- cent or Pleistocene to early Miocene (Tertiary e). Leptothyra glareosa marshallensis Ladd, n. subsp. Plate 9, figures 16—20 Small, globose, thick; body whorl inflated but showing a suggestion of a shoulder; shoulder more prominent on earlier whorls, giving the shell a turreted appearance; suture impressed, descending at aperture; apex flattened; aperture circular, inner lip expanded below; umbilicus narrow and deep, partially filled by a low heavy beaded funicle. Sculpture consisting of fine close-set spiral ribs (about 24 on body whorl), the rib at the shoulder slightly larger than the others; ribs on earlier whorls and those near umbilicus beaded by axial lines. Colored pale brown or reddish brown with indistinct darker axial bands; apex and umbilical area white. Operculum: inside con- vex, warped, multispiral; outside with deep excentric pit with beaded margin, partially surrounded by five concentric flaring ridges. Measurements of the holotype, a Recent shell from Bikini, USNM 648313: height 2.3 mm, diameter 2.6 mm. Operculum of paratype, a Recent shell occurring with holotype, USNM 648314: maximum diameter 1.1 mm, minimum diameter 0.9 mm. Recent shells and fossils from the Marshall Islands have been compared with the types of Gould’s M onilea glareosa (USNM 971 and 24227), with Recent shells col- lected in the Ryukyu (Loo Choo) Islands, and with shells from Japan and the Bonin Islands. The Marshall Island specimens, both Recent and fossil, differ only in the possession of a shoulder that is marked on the body whorl by an enlarged spiral rib. The species described by Pease as Collonia granulosa (1868, p. 92) and re- ferred by Pilsbry to Leptothyra (1888, p. 259, pl. 57, fig. 59) appears to be identical with Gould’s Mom'lea glareosa. Pease’s type was collected on Ponape in the Caroline Islands, not far from the Marshalls, but it does not possess a distinct shoulder. A shoulder like that on the Marshall Islands specimens is found on Recent shells from New Caledonia (Acad. Nat. Sci. Philadelphia 271717). Occurrence: Abundant in the Marshall Islands to- day. Holotype, a Recent shell dredged alive from a depth of 30 fathoms in Bikini lagoon. Six fossil speci- mens from three drill holes on Bikini were recovered from a depth of 110~295 feet; probable age, Recent to Pliocene (Tertiary h). Also present in numerous drill holes on Eniwetok Atoll at depths of 1—890 feet; age, Recent and Miocene (Tertiary f and g). Many opercula representing this species were recovered from several PALEONTOLOGY 53 Eniwetok drill holes from near the surface to 1,777 feet; age, Recent to Tertiary e. Leptothyra picta (Pease) Plate 9, figures 21—23 Collonia picta Pease, 1868, Am. Jour. Conchology 4, p. 91, pl. 11, fig. 1. Leptothyra picta (Pease), Pilsbry, 1888, Manual Conchology, v. 10, p. 256, pl. 69, fig. 35. Minute, strongly turreted; apex flat; suture impressed, descending abruptly at aperture; aperture circular, outer lip thin, inner lip thick and broadly expanded below; umbilicus exceedingly narrow, bordered by a broad beaded rib. Sculpture consisting of about 10 strong spiral ribs alternating fairly regularly with weak secondary ribs. Strong ribs at the suture, the shoulder, near the upper margin of the base, and next to the umbilicus are larger than the others; ribs on earlier whorls, those bordering the suture and near umbilicus are beaded. Measurements of the figured specimen (E—l, 35—40 ft), USNM 648315: height 2.1 mm, diameter 2.3 mm. Occurrence: Many specimens from drill hole E—l on Parry Island, Eniwetok Atoll, at depth of 30—110 feet; age, Recent. Originally described as a Recent shell from the Tua- motu Islands; later, reported from Tahiti, Society Is- lands; rare in the northern Marshalls. The fossils agree in all essential features with the types of L. picta (Acad. Nat. Sci. Philadelphia 38416), but the turreting in the fossils is a little stronger, particularly the strength of the strong spiral rib at the upper edge of the aperture. Leptothyra emenana Ladd, n. sp. Plate 9, figures 24-26 Small; spire low to medium, turreted; apex flat: suture impressed, descending at aperture; aperture subcircular, oblique; outer lip thin, inner lip thickened and on some specimens expanded below; umbilicus narrow, bordered by a large conspicuously beaded spiral rib. Sculpture variable, consisting of about 15 spiral ribs, the 4 that occur on the gently convex peripheral band being larger than those above and below; secondary spirals may alter- nate with larger spirals above the peripheral band; be- low the peripheral band the spirals are subequal in size, all being smaller than the rib next to the umbilicus; all spiral ribs except the lowest three of the peripheral band are more or less beaded. Well-preserved shells show traces of broad radial brown bands. Measurements of the holotype (drill hole F—l, Eniwe- tok, depth 940—950 ft), USNM 648316: height 2.7 mm, diameter 2.8 mm. Paratype (F—1, 880—890 ft), USNM .648317: height 2.3 mm, diameter 2.6 mm. This somewhat variable species is characterized par- ticularly by the nearly flat peripheral band bearing four strong spiral ribs. Occurrence: In all deep holes on Eniwetok and Bikini. On Eniwetok, 40 specimens were recovered from 26 samples. Most of these were in beds referred to the Mio- cene (Tertiary e—g) ; rare in beds that probably are Pliocene (Tertiary h) ; on Bikini a total of six specimens were recovered from the Miocene (Tertiary e and g). Leptothyra sp. A Plate 9, figures 27—29 Minute; spire medium, apex flattened; aperture sub- circular; outer lip thin, inner lip slightly thickened, ex- panded below; umbilicus narrow, deep, puckered by a wide riblike elevation. Sculpture consisting of spiral ribs that are beaded and scalloped by axial lines; on the body whorl four ribs, larger than those above and below, form a peripheral band; three somewhat smaller spirals lie above the band and five obscure spirals lie below it; under magnification, fine threads can be seen between the ribs of the peripheral band and between those that lie above it; the uppermost of the peripheral ribs and the third one in the series are extended as a frill that is scal- loped on part of the body whorl and on earlier whorls. Body whorl retains traces of broad radial bands of brown. Measurements of the figured specimen, USNM 648318: height 2.0 mm, diameter 2.4 mm. The single specimen described may represent an unde- scribed species, but its thin fluted outer lip indicates immaturity, and a specific name is withheld. The white— ness of the shell with its traces of brown suggests that the shell may have been derived from a higher level. It appears to be most closely related to L. emenana, dif- fering chiefly by having scalloped peripheral ribs. Occurrence: Drill hole K—1B, Eniwetok Atoll, at a depth of 642—653 feet; age, late Miocene (Tertiary 9). Family PHASIANELLIDAE Genus PHASIANELLA Lamar-ck Lamarck, 1804, Annales Mus. Histoire Naturelle, v. 4, p. 295. Type (by ruling of Comm: Zool. Nomenclature, Z001. Nomenclature Bull., 1962, v. 19, p. 140): Buccinum austrae Gmelin. Recent, south coast of Australia. Phasianella sp. Plate 10, figures 10, 11 Eight specimens of phasianellid opercula were recov- erede from Miocene beds in three drill holes on Eniwetok and three from hole 2A on Bikini. Six of the opercula from Eniwetok occur in sediments referred to Tertiary 9 (642—898 ft) ; the remaining two, both incomplete, came 54 from a slightly lower level, 873—884 feet, in the top of the Tertiary 1' section. The Bikini specimens are from beds referred to Tertiary f (877—936 ft). Two opercula from the Tertiary marls of the Suva Formation (sta. FB—20) on Viti Levu, Fiji, appear to be identical with the Marshall Island specimens. Operculum convex externally with a broad longitudi- nal off-center bulge, surface polished; internal surface concave with excentric paucispiral nucleus, surface striate. The striae meet the margin at right angles. Measurements of the figured specimen (K—lB, Eni- wetok, 841—853 ft), USNM 648327: maximum diameter 3.4 mm, minimum diameter 2.5 mm, convexity 1.1 mm. Most of the opercula are too large to be assigned to any of the phasianellids recognized from the drill holes. Their size suggests that they belonged to shells having a height of at least 12 mm. Genus GABRIELONA Iredale Iredale, 1917, Malacological Soc. London Proc., v. 12, p. 327. Type (by monotypy): Phasianella nepeanensis Gat- liff and Gabriel. Recent, Australia. Gabrielona raunana Ladd, n. sp. Plate 10, figures 1—5 Small, globose, thin; spire low; smooth whorl of pro- toconch followed by about three rapidly increasing sculptured whorls; aperture broadly ovate, peristome thin, inner lip expanded below; umbilicus narrow; sculp- ture consisting of axial riblets that are coarser on the upper part of each whorl and near the umbilicus than elsewhere. Operculum (preserved in place in holotype) is paucispiral and gently concave externally, this face being marked on the last volution by an outer band of spiral ridges inside which is a wider band of curved axial ridges. Operculum of paratype C, USNM 648322, measures: maximum diameter 0.8 mm, minimum diame- ter 0.5 mm; the interior face is flattened by a shallow spiral depression and a rounded outer edge. Well-pre- served shells have a pink tinge with irregular brown axial streaks extending downward from the suture; on para- type B, similar markings occur on the lower part of the body whorl. Measurements of the holotype (F—l, Eniwetok, 20—45 ft), USNM 648319: height 1.4 mm, diameter 1.4 mm. Paratype A (F—l, Eniwetok, 20—45 ft), USNM 648320: height 2.0 mm, diameter 1.9 mm. Paratype B (E—l, Eni— wetok, 40—45 ft), USNM 648321: height 1.5 mm, diame- ter 1.5 mm. Differs from the type species, G. nepeanensis (Gatliff and Gabriel) by having the inner lip expanded below. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Occurrence: Thirty-four specimens recovered from shallow depths (20—110 ft) in five drill holes on Eniwe- tok Atoll; age, Recent. A single specimen from hole E—l at a depth of 1,865—1,895 feet (Tertiary 6) shows evidence of wear and was probably derived from a higher horizon. Not represented in the extensive Recent col- lections made on Eniwetok and nearby atolls. Genus TRICOLIA Risso Risso, Histoire naturelle des principales productions de l’Europe Meridionale, v. 4, p. 122. Type (by subsequent designation, Gray, 1897, Z001. Soc. London Proc., pt. 15, p. 144) : Turbo pullus Linnaeus. Recent, European seas. Subgenus HILOA Pilsbry Pilsbry, 1917, Acad. Nat. Sci. Philadelphia Proc., p. 207. Type (by original designation): Phasianella thaanumi Pilsbry. Recent, Hawaii. Tricolia (Hiloa) variabilis (Pease) Plate 10, figures 6, 7 Collonm variabilis Pease, 1860, Zool. Soc. London Proc., p. 436. Phaszkmella variabilis (Pease), Pilsbry, 1888, Manual Conchology, v. 10, p. 176, pl. 39a, figs. 21, 22. Pilsbry, 1917, Acad. Nat. Sci. Philadelphia Proc., p. 207. Small, thin, ovate; about four whorls, ventricose; su- ture deeply impressed; aperture subcircular, inner lip callused, slightly extended below and with a deep groove behind it in the umbilical region. Sculpture consisting of fine oblique axial lines; close-set spiral striae visible under magnification on some specimens. Specimens re- taining traces of color show nearly continuous close-set brownish-red spiral lines or lines of dots and may show short thick red axial lines immediately below the suture; axial lines may be bunched in groups of three or four. Measurements of the figured specimens (pl. 10, fig. 6; E—l, Eniwetok, 30—40 ft), USNM 648323: height 1.4 mm, diameter 1.1 mm; (pl. 10, fig. 7; E—l, Eniwetok, 40—45 ft), USNM 648324: height 1.9 mm, width 1.3 mm. Occurrence: Common in many drill holes on Eniwe- ‘ tok Atoll from near the surface to a depth of 852 feet (Recent to upper Miocene, Tertiary 9); four specimens from hole 2B on Bikini at depth of 1,482—1,870 feet (lower Miocene, Tertiary e). Recent shells were col- lected from Bikini, Eniwetok, Rongerik, and Rongelap Atolls. The fossils and the Recent Marshall Island shells are smaller on the average than the shells described by Pease from Hawaii, and they have a somewhat difierent color pattern. The pattern on the Hawaiian shells, as Pease’s name suggests, is exceedingly variable, but on most shells the axial bands seem to dominate over the PALEONTOLOGY 5 5 spiral markings. Some Recent Hawaiian shells, however, exhibit close-set lines of red dots, a pattern that is strongly suggestive of that shown by the Marshall Island material. Tricolia (Hiloa) sp. A Plate 10, figure 9 Minute, thin, ovate; about three smooth ventricose whorls; suture impressed; aperture subcircular; inner lip expanded below with a shallow groove behind it in the umbilical region. Measurements of the figured specimen, USNM 648326: height 0.9 mm, diameter 0.7 mm. Tricolia sp. A should, perhaps, be placed with T. vari- abilis (Pease), but it has fewer whorls, a less prominent groove in the umbilical region, and a more expanded basal inner lip. The single Tongan specimen retains traces of spiral lines of short red dashes on body whorl. Occurrence: Three specimens from the Miocene (Ter- tiary f) Suva Formation on Viti Levu, Fiji (sta. 160); a single specimen from Tongatabu in Tonga (B. P. Bishop Mus, cat. 202976) may represent this species; age, probably Pleistocene. Family NERITOPSIDAE Genus NERITOPSIS Grateloup Grnteloup. 1832, Soc. Linn. Bordeaux Actes. v. 5, p. 129. Subgenus NERITOPSIS 5.8. T ype (by monotypy): N eritopsis moniliformis Grate- loup. Miocene, southern France. Neritopsis (Neritopsis) radula (Linnaeus) Plate 10, figures 12—14 Nerila radulu Linnaeus, 1758, Systema naturae, 10th ed., p. 777. Ncritopsis radula (Linnaeus), Gray, 1899, Zoology, “Blossom,” p. 138. Nor/[(msis rat/Illa (Linnaeus). new subs}')ecies?, Ladd, 1934, B. P. Bishop Mus. Bull. 119, p. 207. pl. 35, fig. 13. Ncritopsis radula (Linnaeus). Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 355, pl. 50, fig. L. N. radula has been reported from the Recent fauna in many parts of the Indo-Pacific region (Marshall, Ellice and Loyalty Islands, New Caledonia, Java, and Mauri- tius) and has previously been found in the Tertiary and younger rocks of Fiji (sta. 160, Viti Levu; stas. L-24, L-35, L-45, L-46, Fulanga; L—120, Ongea; 110B, 110C, Vanua Mbalavu). Single typical specimens were col- lected on Guam from three localities (USGS 20534, 20614, and 20869) in the Mariana Limestone. In Palau the species was found in the Palau Limestone on Uruk- thapel (L'SGS 18322) and on Saipan in the Miocene Tagpochau Limestone (USGS 17723); a mold that may represent N. radula was recovered from the Quaternary beds drilled on Funafuti (core 563A, depth 1,015—1,025 ft). In the Marshall Island drill holes, small unbroken specimens were recovered from cuttings from Bikini (2A, depth 284-290 ft) and from Eniwetok at depths ranging from 20 to 1,715 feet. Three of the six Eniwetok speci- mens are from the Miocene (two from Tertiary f and one from Tertiary e). The small Tertiary specimens, like the large specimen from the upper Tertiary of Viti Levu (Ladd and others, 1934), appears to be more coarsely sculptured than most Recent shells, but the differences are not great and hardly seem to justify the naming of a new subspecies. Measurements of the figured specimen (F—l, Eniwetok, 960—970 ft). I'SNM 648238: height 2.8 mm, diameter 2.6 mm. Family NERITIDAE Genus NERITA Linnaeus Linnaeus, 1758. System11 naturae. 10th ed., p. 776. Type (by subsequent designation, Montfort, 1810, Conchyliologie systématique 2, p. 347) : Nerita peloronta Linnaeus. Recent, West Indies. Subgenus AMPHINERITA Martens Martens, 1887, Systematische Conchylien-Cabinet, v. 2, pt. 11, p. 9. Type (by subsequent designation, Baker, 1923, Acad. Nat. Sci. Philadelphia Proc., v. 75, p. 164): Nerita umlaasiana Krauss. Recent, Africa. Nerita (Amphinerita) insculpta Récluz Plate 10, figures 15, 16 Nerz'ta insculptn Récluz, 1841, Rev. Zool., Soc. Cuvierienne, p. 152. Small, stout; spire low; sculpture consisting of 10 broadly rounded spiral ribs separated by narrow inter- spaces and crossed by fine growth lines; outer lip crenulated by spiral ribs; inner lip and columellar deck smooth. Traces of dark spots are preserved along several of the spiral ribs. Measurements of the figured specimen, USNM 648332: height 4.6 mm, diameter 5.3 mm. Occurrence: Eniwetok Atoll, drill hole F—l, at depths of 680—690 feet and 690—700 feet (figured specimen); late Miocene, Tertiary g. The two fossil specimens are smaller than Recent shells from the same area but probably are immature. They have fewer and coarser ribs than most Recent shells. The type specimen is a Recent shell from Timer; Hedley (1899a, p. 410) found the species living in the lagoon at Funafuti. 56 Nerita (Amphinerita) aff. N. polite Linnaeus Plate 10, figures 17, 18 Small, globose, thick, highly polished; spire low, suture distinct; aperture polished within, outer lip thick, de— scending at the aperture; columcllar deck convex, white, bounded posteriorly by a shallow groove; inner lip feebly dentate. Sculpture consisting of fine growth lines that may be prominent on the upper part of the body whorl close to the suture. Measurements of the figured specimen tF-l, Eniwetok, 930—940 ft), ['SNM 648333: height 3.4 mm, diameter 4.1 111111. The fossils resemble the Recent species N. polita Linnaeus (Tryon, 1888, p. 30, pl. 6, figs. 7—11, pl. 7, figs. 12—231 that occurs in abundance in the Marshall Islands and in many other parts of the Indo—Pacific region. The fossil differs in that its outer lip descends at the aperture, and its columellar callus is set off by a shallow but dis- tinct groove. Occurrence: Eight specimens tone immature) from three deep holes on Eniwctok Atoll at depth of 830—978 feet; age, Miocene (Tertiary f—g). Subgenus RITENA Gray Gray, 1858, Z001. Soc. London Proc., pt. 26, p. 92. Type (by original designation) Nerita plicata Lin— naeus. Recent, Indo—Pacific seas. Nerita (Ritena) palauensis Ladd, n. sp. Plate 10, figure 19 Shell medium sized, spire low; columellar deck irregularly tuberculated, inner lip with two large teeth; edge of outer lip thin, dentate within; sculpture of body whorl 14 or more heavy flattened ribs separated by nar— rower interspaces. Holm‘g/pe: USNM 648330: height 17.3 111111, diameter 20.9 mm. N. pulaucnsfs is related to the Recent N. lineata Gmelin tRippingale and McMichael, 1961, p. 41, pl. 3, fig. 71 from Indonesia and Australia, but the Recent shells have thinner and more numerous ribs and a smooth cohnnellar deck. Occurrence: Holotype and one other specimen from the breceia at the base, of the Palau Limestone on Aulup- tagcl Island (ITSGS 236421, Palau; late Miocene (Ter— tiary (/1; two other specimens from the same horizon nearby, liSGS 17715 and 21290. Nerita (Ritena) aff. N. undata Linnaeus Several clusters of external molds of a large ribbed neritid similar in general features to the variable and widespread Recent N. umlata were collected in 1899 by CHITONS AND GASTROPODS FROM W'ESTERN PACIFIC ISLANDS the U.S.F.C. steamer Albatross from Alofi on the western side of the island of Niue, an island in Tonga lying to the east of the main island group. The samples were col- lected from the third terrace; age, probably Pleistocene. On some of the fossils the ribs are headed by axial lines, a feature not shown by N. undata. N. undata has also been reported from the upper Miocene of Java. Subgenus THELIOSTYLA Mérch Morch, 1852, Catalogus Conchyliorum D. A. d’Aguirra et Galdea, (.‘omes de Yoldi, pt. 1, p. 167. Type tby subsequent designation, Kobelt, 1879, Illustrirtcs Conchylienbuch 2, p. 147): Nerita albicilla Linnaeus. Recent, Indo-Pacific. Nerita (Theliostyla) cf. N. semirugosa Recluz Nerita (Theliostyla) semirugosa Recluz, Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 355, pl. 50, fig. M. Three incomplete and partly crushed specimens from stations 110B and 110C, Ndalithoni Limestone; age, probably Pliocene (Tertiary h), Vanua Mbalavu, Lau, Fiji may be identical with the Recent species (Tryon, 1888, p. 20, pl. 3, figs. 41—43). No additional material collected. Nerita (Theliostyla) sp. A Plate 10, figures 20, 21 Nerilu (’l'helioslgla?) sp. Ladd. 1934, B. P. Bishop Mus. Bull. 119, p. 208, pl. 35, figs. 14, 15. Shell small, subglobose, thick; spire low; columellar deck slightly concave and covered with circular and oval pustules; inner lip bearing rounded widely spaced den- ticles. Outer lip incomplete but apparently dentate within, bordered by a narrow grove and channeled pos- teriorly at its junction with the parietal wall. Surface of body whorl somewhat worn but showing traces of low close-set rounded spiral ribs and fine wavy lines of growth. Measurements of single incomplete specimen, B. P. Bishop Museum, geology No. 1195: height 11.3 mm, diameter 12.8 mm. This specimen was originally referred questionably to Theliostyla and compared with its type species N. albi- cilla Linnaeus. Following reexamination and comparison with additional Recent material it seems certain that the fossil is a Thelz‘ostyla and that it is similar to but not identical with N. albicilla. The most important differ— ence between the fossil and the Recent shells is in the spiral ribs. Those of the fossil are lower and much more numerous than those of any specimens of the variable and widespread Recent species. The fossil probably PALEONTOLOGY represents an undeseribed species, but better type mate- rial should be obtained before it is named. Occurrence: Viti Levu, Fiji (sta. 59); age, probably Miocene. Nerita (Theliostyla) sp. B Plate 10, figure 22 Nerita sp. Ladd, 1945, B. P. Bishop Mus. Bull. 181, p. 356. Shell large, heavy; spire low; sculpture consisting of 14 heavy spiral ribs whose upper surfaces are nearly flat and whose sides are undercut; spaces between ribs fiat— tened and slightly wider than ribs; ribs and interspaces crossed by numerous fine lines of growth that are slightly oblique to axes of ribs; growth lines, near aperture espe- cially prominent; outer lip crenulated by the ribs, coarsely dentate within; columellar deck pustulosc. Diameter of figured specimen, USNM 648331: 31.0 111111. Appears to be closely related to 1V. ca'zu'ia Linnaeus, 21 Recent lndo-Pacific species, but that species shows a small median rib in each depression between the major ribs. The fossil may represent an undescribed species, but the single specimen is incomplete and the apertural features are somewhat obscured by recrystallization. Occurrence: Single specimen from the island of Mango, Fiji (sta. M2DI; age, probably Miocene. Collected by J. E. Hoffmeister. Genus NERITINA Lamarck Lamarck, 1816, Encyclopedic méthodique, Histoire naturelle des vers, v. 3, pl. 455; Liste p. 11. Type (by subsequent designation, Children, 1823, Lamarck’s genera of shells, p. 1111: Neritina pulligera (Nerita pulligera Linnaeus). Recent, fluviatile, India and Melanesia. Subgenus VITTA Mérch Morel}, 1852, Catalogus Conchyliorum D. A. (l’Aguirra et Galdea, Comes de Yoldi, pt. 1, p. 166. Type (by subsequent designation, Baker, 1923, Acad. Nat. Sci. Philadelphia Proc., v. 75, p. 1371: .Ve'rita vir- ginea Linnaeus. Recent, southern Florida to northern South America, estuarine and marine. Neritina (Vitta) oualaniensis Lesson Plate 10, figures 23-25 Xerilimz ouulmiieusis Lesson. Zoologie, v. 2, p. 379. Neritina ulzmensis2 Lesson, Tryon, 1888, Manual Conchology. v. 10, p. 41, pl. 13, figs. 56-68. 1830. Voyage do Lu Cliqizille, ‘-‘ "Ulan" is an old name for the island of Kusaie in the eastern Carolines. Tryon in substituting ulanensis for Lesson’s oualaniensis appears to have attempted to correct Lesson’s spelling of the type locality. 57 Shell small, spire moderately elevated, outer lip thin; inner lip callused, slightly convex, bearing small den- ticles; color pattern consisting of dark wavy lines inter- rupted by white triangular areas in spiral series, each triangle pointing forward, its sides outlined by a dark line. Measurements of the figured specimens (pl. 10, figs. 23, 24 l, USNM 648334: height 6.3 mm, diameter 5.6 111111; (pl. 10, fig. 25) USNM 648335: height (incomplete) 5.0 mm. Occurrence: Two specimens from the Pliocene and Pleistocene of Guam (USGS 20600 and 21377). Recent shells have been widely reported in the Indo—Pacific region, including Queensland, Australia. The species has also been reported from the lower and upper Miocene of Java. Genus CLITHON Montfort Montfort, 1810, Conchyliologie systématique, v. 2, p. 327. Type (by original designation! : Nerita corona Lin- naeus. Recent, rivers of Asia and Indonesia to Melanesia. Subgenus CLITHON s.s. Clithon (Clithon) corona (Linnaeus) Nerilrr corona Linnaeus. 1758, System21 naturae, 10th ed., p. 777. Neritina brevispina Lamarck, 1822, Hist. Nat. Animaux sans Vertebres, v. 6, pt. 2. Theodoxus corona (Linnaeus), Baker, 1923, Acad. Nat. Sci. Phila- delphia Proc., v. 75, p. 155. Theodoxus (Clilhon) corona (Linnaeus), Ladd, 1934, B. P. Bishop Mus. Bull. 119, p. 208, pl. 35, fig. 16, pl. 36, fig. 1. Clithon (Clithon) corona (Linnaeus), Ladd, 1965, Malacologia, v. 2, p. 191. A single worn specimen of this widespread and some- what variable rivcr snail was described and figured by Ladd from the Miocene Suva Formation (Tertiary f) of station 160, Viti Levu, Fiji. No other fossil examples have been collected in the island area. Genus NERITILIA Martens Martens in Martini and Chemnitz, 1879, Systematische Conchy- lien-Cabinet p. 18. Type (by original designation) : Neritina rubida Pease. Recent; fresh water, Tahiti. Neritilia traceyi Ladd Plate 10, figures 26, 27 Neritilia traceyi Ladd, 1965, Malacologia, v. 2, p. 191. Minute, obliquely elliptical, smooth, thick; aperture lunate; inner lip convex, its margin edentulous; columel- lar deck convex, heavily callused, posterior margin of callus broadly convex. 58 Measurements of the holotype, USNM 648336: height 1.9 mm, diameter 2.5 111111. N. tmceyi has the edentulous inner lip that is char- acteristic of Nerz'tilia, but the lip margin is convex, whereas in typical Neritilia it is straight. The inner lip of the fossil is more heavily callused than that of N. rubida (Pease), the type of the genus, but a callused lip comparable to that of the fossil is present on a small brackish-water Neritilia found in abundance of J. E. P. Morrison near the mouths of a coastal river in New Cale- donia. The outer lip of the fossil is worn, and this fact explains, in part, the apparent great thickness of the shell and the shortness of its elliptical outline. Occmv'ence: Holotype (only specimen) from drill hole 2B, Bikini Atoll at a depth of 2,154—2,165 feet; age, early Miocene (Tertiary e). Genus SMARAGDIA Issel Issel, 1869, Malacologia del Mare Rosso, p. 212. Subgenus SMARAGDIA s.s. Type (by subsequent designation, Kobelt, in Martini and Chenmitz, 1879, Systematische Conchylien-Cabinet v. 2, p. 246: Nerita viridis Linnaeus, Recent, Mediter- ranean Sea. Smaragdia (Smaragdia) jogjacartensis (Martin) Plate 10, figures 28—31; plate 11, figures 1, 2 .Vcritina jogjacm‘tensis Martin. 1916; Die Altlnioeiinc fannades West-Progogebirges auf Java, Geol. Reichs—Mus. Leiden Samml., V. 2, no. 6, p. 259, pl. 3, figs. 82, 83. Small; callus thick and broadly convex except near base of inner lip where it becomes the lining of a shallow depression; inner lip bearing fine denticles that are slightly coarser above; outer lip thin. Color pattern con— sisting of three broad spiral bands made up of close-set parallel axial brown lines; lined areas separated by nar- row white spiral bands with short stubby extensions. l\'Ieasurements of the figured specimens (pl. 10, figs. 28, 29; Eniwetok drill hole F—l, 830—840 ft) USNM 648- 337: height 5.2 mm, diameter 5.9 mm; (pl. 10, fig. 30; K—lB, 8417853 ft) USNM 648401: height 2.5 mm, diameter 2.7 mm; (pl. 10, fig. 31; K—IB, 873~884 ft) USNM 648402: height 3.0 mm, diameter 3.6 111111; (pl. 11, figs. 1, 2) ; from Palau (USGS 21308) USNM 648403: height 2.6 111111, diameter 3.3 mm. The color pattern exhibited by S. jogjacartensis, like that of most Smaragdias, is variable. The relative widths of the clear and shaded bands vary as do the lengths and orientation of the secondary branches. Occurrence: Described originally from the lower Mio- cene of Java. In samples from 14 intervals in three deep holes on Eniwetok Atoll (F—l, 830—960 ft; E—l, 860— CHITONS AND GASTROPODS FROM \VESTERN PACIFIC ISLANDS 1,130 ft; K—lB, 842—988 ft) but never in great abun- dance. All the intervals are Miocene (Tertiary e—g); rare specimens were also found at three localities in the marl facies at the base of the late Miocene Palau Lime- stone in the Goikul area, Babelthuap, Palau. Smaragdia (Smaragdia) aff. S. rangiana (Recluz) Plate 11, figures 3, 4 Small, obliquely elongate; spire low, whorls with a well-developed shoulder close to the suture; suture de- scending sharply at aperture. Columellar deck heavily callused above, unevenly depressed below, delimited by a groove that deepens along the base; inner lip denticu- late, the largest denticles lying immediately above the midpoint. Measurements of the figured specimen, USNM 648338: height (incomplete) 3.2 mm, diameter 3.3 mm. The Palauan fossil closely resembles the variable Re- cent species that has been reported from many parts of the Indo-Pacific area (Tryon, 1888, p. 55, pl. 18, figs. 89—92), but seems to have a stronger shoulder; no trace of color pattern is preserved on the single fossil. Occurrence: Single incomplete specimen from late Mio- cene (Tertiary g) marls at the base of the Palau Lime- stone near Goikul, Babelthuap Island, Palau (USGS 21308). Smaragdia (Smaragdia) colei Ladd, n. sp. Plate 11, figures 5—7 Small, obliquely elongate; spire low; body whorl in- flated, with obscure shoulder close to suture. Upper two-thirds of columellar deck covered by thick pad of callus that is separated by a groove from the depressed but gently convex lower third; inner lip denticulate, one or two teeth near the midpoint larger than the others; outer lip thin (broken in most specimens). Color pat- tern consisting of spiral lines of brown dots. On some specimens, including the holotype, lines are arranged in bands of three lines each; on other shells (pl. 11, fig. 7) the lines of dots cover the entire shell uniformly; on a few shells the lines of dots are reduced or entirely absent. Measurements of the holotype (F—l, EniWetok, 880~ 890 ft), USNM 648339: height 5.6 mm, diameter (outer lip incomplete) 5.4 mm. Paratype (F—l, Eniwetok, 830— 840 ft), USNM 648405: height 3.8 mm, diameter 4.1 mm. S. colei is characterized particularly by its depressed lower columellar deck; in the types and many other specimens this deck is sharply set off from the callus above; in a few shells the line of demarkation is less sharp. The color pattern appears variable, as in many neritids. Specimens showing the dots uniformly dis— PALEONTOLOGY tributed strongly resemble the pattern on a specimen from the upper Miocene of East Borneo. (Beets, 1941, p. 21, pl. 1, fig. 30!. The Borneo specimen was referred to the Recent S. rangiana (Récluzl, widely reported from the Indo-Pacific area. Occurrence: Abundant (33 lots containing 77 speci- mens( in all 3 deep holes on Eniwetok Atoll at depths of 780—1,688 feet; age, Miocene (Tertiary e~g). A sin- gle poorly preserved specimen from drill hole 2A on Bikini, depth 967—978 feet (Tertiary 9), probably repre- sents the same species. Smaragdia (Smaragdia) sp. A Plate 11, figures 8, 9 Shell minute, thin; spire low; callus large, moderately convex, very thick above, slightly thickened below; color pattern of body whorl consisting of two spiral rows of short axial brown dashes; in the upper row the lines are paired, in the lower row arranged in groups of three. Measurements of the figured specimen (K—lB, Eni- wetok, 715—727 ftl, USNM 648340: height 1.4 mm, diameter 1.4 mm. Smaragdia sp. A is smaller than S. semari Beets from the late Miocene of East Borneo (Beets, 1941, p. 22, pl. 1, figs. 3143) and has one less spiral row of axial dashes. Occurrence: In drill holes K—lB (depth 716-727 ft) and F—l (depth 660—670 ft! on Eniwetok Atoll in beds referred to late Miocene (Tertiary g‘). The two specimens from Eniwetok are not given a name because they are probably immature. Fragments from drill holes 2A (depth 1,0821/2~1,088 ft) and 2B (depth 1,5761/3—1587 ft) on Bikini in beds referred to Tertiary f and e, respectively, show a somewhat different color pattern but may represent the same species. Genus PISULINA Nevill and Nevill Nevill and Nevill, 1869, Jour. Asiatic Soc. Bengal, V. 38, pt. 2, no. 2, p. 160, pl. 17, fig. 4. Type (by monotypyl: Pisulina adamsiana G. and H. Nevill. Recent, Ceylon. Pisulina subpacifica Ladd, n. sp. Plate 11, figure 10 Minute, globular; spire very low, aperture semilunar; outer lip thick, inner lip thinly ealluscd with a large tooth centered below the midpoint and occupying fully one- third of the length of the lip; no trace of color pattern. Measurements of the holotype, USNM 648341: height 1.2 mm, diameter 1.3 mm. Occurrence: Holotype, the only specimen, from drill hole 2B on Bikini at depth of 789—799 feet; age, late Miocene (Tertiary g). 59 The single large tooth differentiates this species from all other neritids reported from the island area. The genus has previously been known only from a few species living in India and Ceylon. The type species is a larger shell (the single fossil may be immature) with a higher spire. Family LITTORINIDAE Genus TECTARIUS Valenciennes Valenciennes, 1833, Coquilles, in Humboldt and Bonpland, Voy- age aux regions équinoxiales du Nouveau Continent, v. 2, p. 271. Type (by monotypyl: Tectarius coronatus Valen- eiennes. Recent, Indo-Pacific. Subgenus SUBDITOTECTARIUS Ladd, n. subgen. Type: Tectarius (Subditotectarius) rehderi Ladd, n. sp., Miocene (Tertiary fl, Bikini Atoll. Small, stout; spire conical, base convex; marked with beaded spiral ribs and slightly oblique axial lines; strongly lirate within. Distinguished by subdued sculpture; the strong tuber- cles that characterize other subgenera are represented only by small beads. Tectarius (Subditotectarius) rehderi Ladd, n. sp. Plate 11, figures 11—13 Small, conical; whorls flat, base convex, imperforate; aperture broadly ovate, columella thickened below by a broad tooth; outer lip thin, strongly lirate within. Sculpture above the periphery consisting of five or six regularly spaced spiral ribs, the ribs close to the periphery being the strongest; on the base a strong rib lies im- mediately below the periphery and smaller ones lie be— tween it and the eolumella. Measurements of the holotype, USNM 648342: height 2.8 mm, diameter 2.4 mm. The apertural features including the lirate interior and the eolumellar tooth seem to place the fossils clearly in the genus Tectarius. In general form and outline the shells resemble Plesictrochus, a cerithid that occurs with them. The sculpture of the fossils is basically similar to that of Tectarius s.s. but is much subdued. It is not known to be closely related to any living species. Occurrence: Holotype from drill hole 2A on Bikini Atoll from a depth of 1,051—1,057 feet; a second specimen from F—l, Eniwetok at a depth of 960—970 feet; age, early Miocene (Tertiary fl. Family IRAVADIIDAE Genus IRAVADIA W. T. Blanford Blanford, W. T., 1867, Jour. Asiatic Soc. Bengal, v. 36, pt. 2, no. 1, p. 56—58, pl. 13, figs. 13, 14. 60 Type (by monotypy): Iravadfa ornate Blanford. Brackish water, Recent, India. Small Risso‘ina-like shells with strong spiral ribs and a eallused unbroken aperture that is effusive anteriorly. Shell covered with a heavy periostracuni. The type species lives in the brackish waters of the Irrawaddy delta, but another species lives under stones at extreme low water (Nevill, 1885, p. 97}, and it is apparently marine. Iravadia gardnerae Ladd, n. sp. Plate 11, figures 14, 15 Shell small, slender. Protoeonch consisting of about two smooth whorls; later whorls gently convex, sutures impressed; body whorl with eight strong spiral ribs that are slightly narrower than the spaces between; penulti- mate whorl with four exposed ribs, earlier whorls with less; aperture oval, continuous, with a distinct anterior canal; interior of outer lip with three low elongate ridges. Measurements of the holotype, USNM 648343: height 3.3 mm, diameter 1.3 mm. The fossil species closely resembles I. annulata Dun- ker (:1. trochlearis (Gould! i from Japan and the China coast, but shells of the Recent species are larger and stouter and the aperture is more heavily callused and less effusive anteriorly. The ridges inside the outer lip of the Recent shells are obscured by callus; most speci- mens show only one ridge (posterior), a few show two, and on rare shells all three are discernible. ()eeurrenee.‘ A total of 41 specimens were found in the cuttings from the three deep holes 011 Eniwetok (F—l, 850—910 ft; E~1, 670—790 ft; K—lB, 8004936 ft); one specimen was recovered from a core in hole 2A on Bikini at 935 feet, 6 inches. Most of the occurrences are in beds referred to Tertiary g, but a few are from beds (below 860 ft) that are referred to Tertiary f. The holotype is one of a dozen specimens from hole K—IB, depth, 831~ 842 feet. Family RISSOIDAE The rissoids include a great variety of small or minute high-spired shells that are extraordinarily abundant today in coral reef environments, particularly in lagoons. This abundance is not reflected in collections of fossils made from elevated reefs because preservation in such structures is generally poor. Well—preserved rissoids are found in abundance in drill holes through lagoonal beds on reef islands and in marly sediments laid down in shallow waters near volcanic islands. In the present report the arrangement of genera and subgenera given by Wenz (193844) has been followed fairly closely. A total of 9 genera, 17 subgenera (1 de- CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS scribed as new), and 54 species and subspecies has been recognized. Because many are represented by one or by only a few specimens, it is diflicult or impossible to determine limits of variation. If more material were available, the species list might be shortened. Genus PUTILLA A. Adams A. Adams, 1867, Z00]. Soc. London Proc., p. 312, 315. Type (by monotypy): Putilla lucida A. Adams. Re- cent, Japan. Includes very small short-spired shells with smooth or striate rounded whorls and a thickened outer lip. Subgenus PSEUDOSETIA Monterosato l’swu/osvlia ,l/ml/t'rus/iln, 1884. (‘onehiglie Littorali Mediterrane, p. 33. Type (by subsequent designation, Bucquoy, Dautzen- berg, and Dollfus, 1898, Mollusques Marins du Roussil- lon, v. 2, p. 7721: Bissau turgida Jeffreys. Recent, Nor- way. Putilla (Pseudosetia) morana Ladd, n. sp. Plate 11, figures 16, 17 Minute, elongate, with blunt apex; smooth convex whorl of protoconch followed by 31/3 gently convex sculp- tured aperture broadly oval, slightly constricted, peristome entire, inner lip thinly callused, edge of outer lip sharp, slightly thickened be— hind. Sculpture consisting of fine spiral striae over the whorls; imperforate; entire surface of the postnuclear whorls. l\’Ieasurements of the holotype, USNM 648344: height 1.1 mm, diameter 0.4 mm. The Eniwetok fossil resembles the larger Putilla semi— striata Montague, a Recent European species, but the fossil is stouter and has a more blunt apex. Occurrence: Single specimen from drill hole E—l, Eni- wetok Atoll, at a depth of 1,805—1,835 feet; age, early Miocene (Tertiary e). Subgenus PARVISETIA Monterosato Monterosato, 1884, Nomenclatura generica e spezifica di aleune conchiglie mediterranee, p. 73, Palermo. Type (by monotypy): Rissoa scillae Seguenza. Re— cent, Sicily. Putilla (Parvisetia) goikulensis Ladd, n. sp. Plate 11, figures 18—20 Minute, ovate, with short spire and blunt apex; about four smooth convex imperforate, aperture broadly rounded, slightly constricted, peristome entire, outer lip thin, on some specimens slightly thickened whorls; behind. PALEONTOLOGY Measurements of the holotype, USNM 648345: height 1.1 nun, diameter 0.5 nnn. Paratypc, USNM 648346 measures: height 0.9 mm, diameter 0.5 mm. P. goikulensis closely resembles P. scillae (Seguenza), the type of Paroisetia, but is smaller, more robust, and has a relatively smaller aperture. Occurrence: Abundant in the late Miocene (Tertiary g1 marls at the base of the Palau Limestone on the Goikul Peninsula, Babelthuap Island, Palau. (USGS 21301, 21308 {types}, 21310). Putilla (Parvisetia) suvaensis Ladd, n. sp. Plate 11. figures 21, 22 Minute, ovate. with short spire and blunt apex; about four smooth whorls, fattened below a weak shoulder; aperture subeircular, slightly constricted; peristome en— tire, margin of outer lip thin but thickened behind into a varix. Measurements of the holotype, I'SNM 648347: height 0.9 mm, diameter 0.6 mm. Putilla suvaensis has a shorter spire and less convex whorls than P. (P.) goikulcnsis from beds of comparable age in Palau. Occurrence: Three specimens from the Suva Forma- tion, Viti Levu, Fiji lstas. 160, FB-20 lholotypcl and MR~20); age, Miocene (Tertiary f). Genus CINGULA Fleming Fleming, 1828, British animals, 1). 297, 305. Type thy subsequent designation, Gray, 1847, Zool. Soc. London Proc. p. 1531: Turbo cingillus Montagu. Recent, Atlantic coasts of Europe. Small shells with gently convex whorls that may be smooth or spirally striate; outer lip sharp or slightly thickened. Subgenus PERINGIELLA Monterosato Monterosato. 1878. Giorn. sci. nat. econ. Palermo, v. 13. p. 87. Type thy monotypyl: Rissort lace/s Monterosato. Re- cent, Mediterranean Sea. Includes minute to small species with blunt apex and slightly thickened outer lip. Cingula (Peringiella) parryensis Ladd, n. sp. Plate 11, figures 23, 24 Small, elongate-oval with large body whorl, short spire, and blunt apex. Protoconch has about 11/2 gently con- vex, polished, whorls showing fine axial lines under high magnification, coiled to form an apical depression; about three subsequent whorls, bearing faint spiral lines; suture 61 slightly channeled, bordered below by an obscure ele- vated thread. Aperture oval, angled above, peristome complete; inner lip callused, slightly extended below; edge of outer lip sharp, thickened behind by a riblike callus. Measurements of the holotype, USNM 648348: height 1.7 111111, diameter 0.8 mm. ('ingula parryensz's resembles the Recent (7. lampra described by Suter (1908, p. 29) from New Zealand, but that species does not have the depressed apex exhibited by the fossil. Occurrence: Holotype and only specimen from drill hole E—l on Eniwetok Atoll at a depth of 700—710 feet; age, late .Miocene (Tertiary g). Cingula (Peringiella) cf. C. roseocincta (Suter) Plate 11, figures 25, 26 Minute, globose, with blunt apex, short spire, and large body whorl. Protoconch consisting of 11/2 smooth convex whorls, followed by about 21/2 smooth gently convex subsequent whorls. Suture well impressed, aper- ture broadly elliptical; peristome complete in adult specimens, flaring slightly below, with a deep groove behind inner lip in the umbilical region; edge of outer lip thin, thickened behind into an inconspicuous callus. Measurements of the figured specimen, USNM 648349: height 1.0 mm, diameter 0.6 mm. The fossil shells appear to be closely related to C. roseom'ncta (Suter, 1908, p. 29, pl. 2, fig. 26; 1913415, p. 209, pl. 12, fig. 171 and may be identical with it. One of the characteristics of the living shells is the color pattern: pink early whorls and pink bands on the body whorl. The fossils show no trace of color and this lack coupled with the general simplicity of form of these minute shells would seem to make a positive identifica- tion unwarranted. Occurrence: Abundant in the late Miocene inarls (Ter— tiary g1 at the base of the Palau Limestone on Goikul Peninsula, Babclthuap Island, Palau (USGS 21301, 21304 (figured specimen) ,21308 and213101 ;a single speci- men from drill hole E—l, Eniwetok Atoll, at depth of 620— 630 feet (Tertiary {1); four specimens from drill hole MIT—4 from a depth of 41 feet are Recent in age. Genus AMPHITHALMUS Carpenter Carpenter. 1864. British Assoc. Adv. Sci. Rept., 1863, p. 614, 656. Type «by original designation) : Amphithalmus in— clusus Carpenter. Recent, California. The genus Amphithalmus includes small elongate shells with a blunt apex. In Amphithalmus s. s. the oval aper- ture is surrounded by a double peristome. 62 Subgenus CEROSTRACA Oliver Oliver, 1915, New Zealand Inst. Trans, v. 47, p. 521. Type (by original designationl: (Verostraca {redalei ()liver. Recent, Kermadec Islands. Thin ovate shells with impressed suture; aperture entire, sometimes detached; outer lip with a Varixlike callosity. Amphithalmus (Cerostraca) jeficoati Ladd, n. sp. Plate 11, figures 27—31 CHITONS AND GASTROPODS FROM WESTERN Small, thin, ovate; about five convex whorls; suture ‘ impressed; aperture broadly lenticular to subcircular; margin of callus of inner lip distinct, in some shells sepa— rated from the body whorl; outer lip thin, slightly ex- panded with a conspicuous callosity a little distance behind the edge. Shell smooth or with rounded slightly oblique axial ribs that are best developed on the cen- tral part of the body whorl. Measurements of the holotype (smooth shell from E—~1, 840—850 ftl USNM 648350: height 1.9 mm, diameter 1.2 mm. Paratype A (weakly ribbed shell from K—lB, 9687-978 ft), USNM 648351,: height 1.9 mm, diameter 1.2 mm, Paratype B (strongly ribbed shell from E~1, l,010—1,020 ft), USNM 648352: height 2.3 mm, diameter 1.3 mm. Some of the Marshall Island fessils show a detached aperture comparable to that of the Recent type species ('. iredalez‘ Oliver, but on other specimens there is no gap between the inner lip and the shell, though the margin of the inner lip is distinct. Some of the fossils are smooth, as is the type specimen, others have well- developed axial ribs on the lower whorls, all gradations between these two conditions being recognizable. Occurrence: 111 all three deep drill holes on Eniwetok Atoll at depths of 62()—2,060 feet but never in abundance; age, Miocene (Tertiary g—e). A single specimen from hole F~1 at a depth of 55—60 feet is Recent. It is more slender than the older shells and has 61/3 smooth whorls but is not recognized as a distinct species. One specimen in hole 2A on Bikini at a depth of 935A946 feet is re- ferred to Tertiary (1; three specimens in hole 213 on Bikini from 1,870—1,944 feet are referred to Tertiary e. Amphithalmus (Cerostraca?) myersi Ladd, n. sp. Plate 11, figures 32, 33 Very small, elongate—ovate, robust; about 11/; smooth convex whorls of protoconch followed by three gently convex sculptured whorls, each of the subsequent whorls with an obscure shoulder about a third of the way below the moderately impressed suture; aperture sub- PACIFIC ISLANDS circular; inner lip thinly callused, outer lip sharp but expanded behind into an inconspicuous varixlike cal- losity. Sculpture consisting of fine spiral lines. Measurements of the holotype, USNM 648353: height 1.5 mm, diameter 0.9 mm. Reference of A. myersi to Cerostraca is questioned because of the presence of fine spiral sculpture. The species is smaller and more slender than A. jeffcoati that occurs with it in drill hole E—l on Eniwetok. Occurrence: Holotype and only specimen from drill , hole E—1, Eniwetok Atoll, at a depth of 770—780 feet; age, late Miocene (Tertiary g). Subgenus PISINNA Monterosato Monterosato, 1878, Giorn. sci. nat. econ. Palermo, V. 13, p. 86. Type (by monotypyl : Rissoa punctulum Philippi (2R. glabrdta auct.=R. seminulum Monts=R. sabulum Cantraine:R. mandralisci Aradas). Recent, Mediter- ranean Sea. Small elongate-oval to pupoid _shells with oval to sub— circular aperture; smooth or with axial folds. Amphithalmus (Pisinna) bikiniensis Ladd, n. sp. Plate 12, figure 1 ‘Minute, pupoid, stout, polished; 11/2 moderately con- vex whorls of protoconch followed by about four flat- tened whorls; suture impressed; imperforate; aperture broadly ovate, slightly constricted; inner lip callused, its boundary sharply defined; outer lip sharp, thickened within. Shell smooth or with a few obscure axial folds on body whorl. Measurements of the holotype (2B, Bikini, 1,839—1,85O ft), USNM 648354: height 1.7 mm, diameter 0.7 mm. A. (P.) bikiniensis resembles the Recent Rissoa sub- fusca Hutton from the New Zealand area (Suter, 1913— 15, p. 210, pl. 12, fig. 18). Iredale (1915, p. 254) later placed R. subfusca in Estea (=Pisirma), but that species has more whorls and shows traces of microsmpic spiral striation. Occurrence: In drill hole 2B on Bikini Atell; total of 17 specimens in 8 lots at depths of 1,807~1,892 feet; age, early Miocene (Tertiary e). Genus ALVANIA Risso Risso, 1826. Histoire naturelle des principales productions de l’Europe méridionale, v. 4, p. 140. Type (by subsequent designation, Monterosato, 1884, Conchiglie Littorali Mediterranee, p. 19): Risso‘a mon- taqui Payraudeau:R. sardea Risso. Recent, Mediter- ranean Sea. PALEONTOLOGY Alvania 5.3. Small robust conical shells with a sharp apex and an elongate-oval aperture; bearing strong axial ribs and weaker spirals; outer lip thickened. Subgenus TARAMELLIA Seguenza Seguenza, 1903, Palaeontographica Italica, v. 9, p. 53—54. Type (by monotypy'): Turbo zetlandica Montagu. Recent, Europe. Small elongate to conical shells with strong spiral ribs and equally strong axial ribs except below periphery; aperture circular, peristome double. Alvania (Taramellia) corayi Ladd, n. sp. Plate 12, figure 2 Minute, broadly conical, stout; apex sharp; protoconch large, consisting of about two smooth whorls; later whorls flat, suture incised; imperforate; aperture sub- circular; lip double, inner one continuous, outer one thickened. Sculpture consisting of strong spiral ribs and somewhat weaker axial ribs; axial sculpture much re- duced on lower half of body whorl. B'Ieasurements of the holotype, USNM 648355: height 1.6 mm, diameter 1.3 mm. The Eniwetok fossil is not turreted as is the type ‘ species of Tarantellia; its whorls are flatter and its outer lip is much thicker than in the type. Occurrence: Seventeen specimens from several drill holes on Eniwetok Atoll to depths of 60 feet (holotype from Mil—4, depth 35—36 ft); all occurrences probably Recent. Alvania (Taramellia) kenneyi Ladd, n. sp. Plate 12, figure 3 Minute, conical, solid; protoconeh large, bulbous, con- sisting of about 21/_>,smooth whorls; later whorls flat, suture deeply incised; imperforate; aperture circular; inner lip double. Sculpture of body whorl consisting of six strong spiral ribs, the upper two of which are cut into sharp upturned projecting points by axial ribs that give the shell 21 stellate appearance when viewed from above. Measurements of the holotype (E—l, Eniwetok, 1,746— 1,777 ft), I’SNM 648356: height 0.8 mm, diameter 0.5 111111. .1. lrenneyz' is smaller than A. rorayi, has a more deeply incised suture and a thinner outer lip. Occurrence: Six specimens from drill hole E-l, Eni- wctok Atoll, at depths of 830—1,925 feet; age, Miocene (Tertiary g and e). 63 Genus MERELINA Iredale Iredale, 1915, New Zealand Inst. Trans, v. 47, p. 449. Type (by original designation): Rissoa cheilostoma Tenison-Woods. Recent, Tasmania. Subgenus MERELINA s.s. Includes moderately solid strongly clathrate shells; protoconch spirally striate, peristome continuous, dupli- cated internally. Merelina (Merelina) pisinna (Melvill and Standen) Plate 12, figures 4, 5 Aluam'a pisirma Melvill and Standen, 1896, Jour. Conchology [Leeds], V. 8, p. 305, pl. 11, fig. 60. Very small, slender, stout; whorls of protoconch about two, convex, bearing spiral striae; subsequent whorls, three, gently convex, separated by a deeply lirate suture; imperforate; aperture rounded, outer lip thick- ened with a double wall. Sculpture clathrate, consisting of strong spiral ribs, (3 exposed on penultimate whorl, 5 on body whorl, below which are 2 or 3 short nearly smooth spirals) crossed by equally strong axial ribs (18 on body whorl), beaded at intersections with spirals; axial ribs obsolete on basal part of body whorl. Measurements of the figured specimen (E-l, Eniwetok, 850—860 ft), I’SNM 648357: height 1.9 mm, diameter 0.9 mm. M. pisinna is smaller and proportionately shorter than the type species M. cheilostoma (Tenison-Woods), but . I have not seen specimens. The clathrate sculpture pattern of M. pisirma is matched almost exactly by M. granulosa (Pease), a Recent species from Hawaii (USNM 345037), but the Hawaiian shells have a smooth and glossy protoconch. : Only a few of the two dozen fossils from the Marshall Islands show traces of spiral sculpture 0n the whorls of the protoconch, and these traces can be clearly seen only under high magnification. Occurrence: In drill holes on Eniwetok at depths of 620—930 feet; in beds referred to Miocene (Tertiary f and g); in drill holes on Bikini at depths of 925—1,944 feet; early Miocene (Tertiary e and 1‘); two specimens were recovered from the Suva Formation on Viti Levu, Fiji (sta. FB~20); age, Miocene (Tertiary f). The species was originally described from the Loyalty Islands and has been reported from the Kermadecs. Subgenus LINEMERA Finlay Finlay. 1924, New Zealand Inst. Trans, v. 55, p. 483. Type (by original designation): Rissoa gradata Hut- ton. Recent, New Zealand. 64 CHITONS AND GASTROPODS FROM WESTERN Includes shells with clathrate sculpture as in Merelina s.s., but with smooth and g10ssy protoconch and a single rimmed aperture. Merelina (Linemera) telkibana Ladd, n. sp. Plate 12, figures 6, 7 Very small, robust; about two smooth convex whorls of protoconch followed by about three flattened sculp- tured whorls; suture deeply incised; aperture broadly ovate, peristome entire, umbilical chink present, outer lip thickened to form a varix. Sculpture consisting of moder- ately strong axial ribs that become obsolete on the basal part of the body whorl and weak spirals that are promi- nent only on the base of the last whorl. Measurements of the holotype, USNM 648358: height 1.9 111111, diameter 1.0 mm. The axial ribs of M. telkibona are much finer and more numerous than those of Rissoa gradata Hutton, the type of Linemera. Occurrence: A total of 14 specimens from late Miocene (Tertiary gl marls at the base of the Palau Limestone near Goikul, Babelthuap Island, Palau (USGS 21301). Genus PARASHIELA Laseron linseron. 1956, Australian Jour. Marine and Freshwater Research, V. 7, no. 3, p. 439. Type (by original designatiom: Paras-Mela ambulata Laseron. Recent, Great Barrier Reef, Australia. Short broad shells with widely spaced axial ribs and a single spiral rib at the shoulder. Parashiela beetsi Ladd, n. sp. Plate 12, figures 8, 9 Minute, short, white, translucent; protoconch of 11/2 glassy rapidly enlarging whorls followed by about 31/2 strongly shouldered sculptured whorls; aperture sub- circular, peristome complete; outer lip with a double wall that is thickened behind to form a low varix. Sculp- ture consisting of fine widely spaced axial ribs and a single spiral rib at the shoulder. Measurements of the holotype, USNM 648368: height 1.4 mm, diameter 0.9 mm. Paratype, USNM 648369: height 1.5 mm, diameter 1.0 mm. P. beetsi has the unusual sculpture that characterizes the type species (and only other known speciesl P. am— bulata, but it differs by possessing a double-walled outer lip that is thickened behind to form a low varix. A similar type of open sculpture is exhibited by Rissoa in- m'sibz'li's Hedley from a Funafuti lagoon beach (Hedley, 1899a, p. 418), but that species has three prominent . spiral ribs. PACIFIC ISLANDS Occurrence: Two specimens from drill hole F—8—C on Eniwetok Atoll a depth of 1942 feet; age, Recent. Genus ZEBINA H. and A. Adams H. and A. Adams, 1854, Genera Recent Mollusca, v. 1, p. 328. Type (by subsequent designation, G. Nevill, 1885, Hand list Mollusca Indian Mus, pt. 2, p. 93): Rissoina coronata Recluz. Recent, Mauritius. Subgenus ZEBINA s.s. The type species is smooth except for the early whorls which are axially ribbed; the outer lip is thickened with one or more tubercles on the anterior part. No examples of Zebz'na s.s. have been found in the fossil faunas of the island area. Subgenus CIBDEZEBINA Woodring Woodring, 1928, Carnegie Inst. Washington Pub. 385, p. 369. Type (by original designation): Rissoina browniana d’Orbigny. Recent, West Indies. Small smooth shells with flat whorls and a varicose outer lip that is extended forward; outer lip with a den— ticle near the posterior angle and a second denticle near the base. Zebina (Cibdezebina) metaltilana Ladd, n. sp. Plate 12, figure 10 Small, slender, smooth, and polished; about three con— vex whorls of protoconch, six flattened subsequent whorls; suture linear or lightly impressed; aperture oval with acute posterior angle and broad shallow anterior channel; inner lip callused, outer lip thickened into a smooth varix and extended forward; outer lip with a broad but prominent denticle near the posterior angle and a less conspicuous dentical near the base; siphonal fasciole slightly swollen. Measurements of the holotype (drill hole 2B, Bikini Atoll, 1,860—1,870 ft), USNM 648359: height 3.5 mm, diameter 1.4 mm. Paratype (drill hole A—l, Eniwetok Atoll, 136—138 ft), USNM 648360: height 3.1 mm, diameter 1.2 mm. The Marshall Island shells agree in all important features with the type of Cibdezebina—Rissoma brown— iana—known from Miocene to Recent in the Caribbean area (Woodring, 1928, p. 370), but it is distinctly more slender in outline. The holotype of Z. metaltilana shows both denticles on the outer lip, but in many specimens, both Miocene and Recent, the anterior denticle is not developed. Occurrence: In many drill holes on Bikini and Eni- wetok Atolls at depths of 1—2,349 feet but never in great abundance; age, Recent to early Miocene (Tertiary e). PALEONTOLOGY A single specimen was recovered from the Suva Forma- tion on Viti Levu, Fiji (sta. FB—20) ; age, Miocene (Tertiary f) ; a few specimens were dredged from a depth of 25 fathoms in the Bikini lagoon. Subgenus MORCHIELLA G. Nevill Nevill, 1885, Hand list Mollusca Indian Mus., pt. 2, p. 88. Type (by original designation) : Rissm'na gigantea Deshayes. Recent, Philippine Islands. Small to medium-sized solid shells whose apical whorls are characteristically more strongly sculptured than later whorls. Zebina (Morchiella) cf. Z. cooperi (Oliver) Plate 12, figures 11, 12 Medium in size, stout; about 11/2 smooth convex whorls of protoconch and five or six flattened subsequent whorls; most, or all, of the whorls above the body whorl bear slightly oblique axial ribs and these are strongest near the apex; suture hardly discernible; aperture sublen— ticular, posterior angle Sharp, anterior channel indistinct, inner lip callused; outer lip thickened and extended for- ward, with one or two broad low denticles inside, one near the base, the other, if present, at about the midpoint. Measurements of the figured specimen, USNM 648361: height 5.7 mm, diameter 2.3 mm; another specimen, USNM 648362, probably immature, measures: height 3.3 nnn, diameter 1.5 mm. Some of the Marshall Island specimens are slightly more slender than the shell described from the Kermadecs (Oliver, 1915, p. 520), and show two rather than three low tubercles inside the outer lip; they likewise have a less distinct posterior canal. In describing the Kermadec shell, Oliver mentioned “3 minute longitudinal plications” on the parietal wall near the posterior canal. These do not appear on his published figure nor on specimens from the type area identified by Oliver, nor can they be seen on the Marshall Island shells here described. Occurrence: Two specimens from drill hole E—l on Parry Island, Eniwetok-Atoll, at depth of 110—120 feet (figured specimen) and 10—20 feet (immature specimen) ; age, Recent. A single Recent shell was also collected from drift on Enybarbar Island, Rongelap Atoll. A fos- sil from drill hole 2B on Bikini Atoll at a depth of 2,235— 2,246 feet; age, early Miocene (Tertiary e); it may be a Recent shell pumped in from the mud pits. Zebina (Morchiella) killeblebana Ladd, n. sp. Plate 12, figures 13. 14 Medium in size, stout, polished; spire short, diameter of shell slightly exceeding one-half the height. \Vhorls of spire about six, first three showing faint traces of 65 axial ribs, early whorls flat sided, later whorls gently convex; suture not impressed; aperture semicircular; inner lip heavily callused, with a denticle next to the acute posterior angle, anterior channel broad and shal- low; outer lip sharp but thickened behind the peristome and slightly extended forward, bearing two or three low denticles inside. Measurements of the holotype, USNM 648363: height 5.6 mm, diameter 3.0 mm. Paratype, a smaller shell that may be immature, USNM 648364: height 3.2 mm, diame- ter 1.8 mm. The fossil is closely related to the Recent Z. tridentata, Michaud, widely distributed in the Indo-Pacific area, but the Recent shell is appreciably more slender. Occurrence: Eniwetok Atoll in drill hole E—1, depth 960~970 feet (holotype) and in drill hole F—l, 930—940 feet (paratype); age, early Miocene (Tertiary f). Subgenus AILINZEBINA Ladd, n. subgen. Type: Zebina (Az'linzebina) abrardi Ladd, n. sp. Small, slender; protoconch consisting of two smooth whorls coiled at a slight angle to remainder of spire; early subsequent whorls bearing heavy axial ribs that become finer and more numerous on later whorls; spiral sculpture conspicuous only on body whorl; siphonal fasciole heavy but ill defined. Resembles Morehiella in that there is a progressive reduction in axial sculpture, but in Ailinzebt'na the axials are not obliterated, even on the body whorl. Zebina (Ailinzebina) abrardi Ladd, n. sp. Plate 12, figures 15-18 Small, slender; two smooth whorls of protoconch coiled at slight angle to axis of spire; about six gently convex subsequent whorls; the early ones bearing heavy slightly oblique axial ribs that become progressively smaller and more numerous on later whorls; suture impressed; aper- ture lenticular, posterior channel narrow and moderately deep; anterior channel broad and shallow; outer lip thickened and extended forward; spiral threads are most conspicuous on the body whorl on and near the heavy siphonal fasciole. Measurements of the holotype (pl. 12, figs. 15, 16) a Recent shell from Bikini, USNM 648365: height 3.9 mm, diameter 1.3 nnn. Paratype A, (pl. 12, fig. 17) a fos- sil from drill hole En—4, depth 11 feet, Eniwetok, USNM 648366: height 2.9 111111, diameter 0.9 mm. Paratype B, (pl. 12, fig. 18) a fossil from (ll'ill hole 2B, depth 1,450— 1,461 feet, Bikini, USNM 648367: height (incomplete) 2.3 mm. diameter 0.9 mm. Occurrence: Living in the northern Marshall Islands (Bikini and Rongerik); the holotype is at Recent shell 66 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS dredged from the Bikini lagoon at a depth of 20 fathoms. Fourteen fossils were recovered from several drill holes on Eniwctok to depths of 60 feet, and two specimens were obtained from drill hole 2B on Bikini at depths of 1,450« 1,608 feet in early Miocene (Tertiary e—fl. Genus ZEBINA s. l. Zebina? sp. A Plate 12, figure 19 Small, stout; whorls gently convex, with strong axial ribs; 27 ribs and fine spiral threads on last whorl; inner lip with a single strong denticle anteriorly; outer lip with low widely spaced internal ribs. Measurements of the figured specimen, USNM 648370: height 2.7 mm, diameter 1.2 mm. The single fossil has an incomplete outer lip. The well-developed axial ribs combined with the strong anterior denticle differentiates this species from others found in the area; if better type material were available, the species might be recognized as belonging to a new subgenus. Occurrence: Drill hole 2B, Bikini Atoll at a depth of 2,112e2,128 feet; early Miocene (Tertiary e). Genus RISSOINA d’Orbigny d’Orbigny. 1840. Voyage dans I'Amerique meridionnle. \'. 5. p. 395. Subgenus SCHWARTZIELLA Nevill Nevill, 1884, Hand list Mollusca Indian Mus, pt. 2, p. 82. Type (by original designationl: Rissoina bryerea (Montagul [Turbo]. Recent, Cuba. Includes strongly ribbed species some of which also bear spiral striae; the oval aperture is slightly angled below. Rissoina (Schwartziella) gracilis (Pease) Plate 12, figure 20 Rissoa gracilis Pease, 1860, Z001. Soc. London Proc., p. 438. Rissoina gracilis Garrett, 1873, Acad. Nat. Sci. Philadelphia, Proc., p. 211, pl. 2, fig. 8. Tryon, 1887, Manual Conchology 9, p. 373, pl. 55, fig. 42. Small, slender; about three glossy convex whorls of protoconch followed by six gently convex sculptured whorls; suture margined; aperture oval, anterior chan- nel broadly rounded, moderately deep; inner lip callused, outer lip extended forward near its midpoint, thickened to form a varix. Sculpture consisting of strong slightly oblique axial ribs almost as wide as the intervening spaces; ribs flexuous on body whorl. Measurements of the figured specimen, B. P. Bishop Museum, geology No. 1340: height 3.0 mm, diameter 0.9 mm. The species appear to be well named, for it is more slender than any other Rissoina found in the island area. Occurrence: One specimen, about 1 mile southwest of Houma, Tongatabu, Tonga; altitude 35 feet; age, prob- ably Pleistocene. The Recent shell briefly described (without measurements) by Pease was collected in Hawaii; Garrett’s specimens came from Fiji; Tryon men— tions the Society Islands as well as Fiji. Rissoina (Schwartziella) aff. R. flexuosa Gould Plate 12, figures 21, 22 Small, stout; two smooth whorls of protoconch followed by about seven sculptured gently convex whorls; suture slightly impressed; aperture broadly lenticular, posterior channel narrow; anterior channel wide, Slightly under- cutting the columella; outer lip thickened; subsequent whorls bearing strong narrow, straight or slightly oblique axial ribs, 17—21 on the body whorl; traces of spiral sculpture are preserved on the lower part of the body whorl on most specimens. Siphonal fasciole low, not sharply defined. Measurements of the figured specimen, USNM 648382: height 4.0 mm, diameter 1.5 mm. The fossils are more slender than the Recent Australian shell (Gould, 1861, p. 400), and their spiral sculpture is less well developed. Occurrence: Four specimens from drill hole E—l on Eniwetok Atoll at depths of 40—45 feet (figured speci— men) and 60—70 feet; age, Recent; a specimen from drill hole 2B on Bikini Atoll at a depth of 1,492—1,503 feet should be referred to Tertiary e, but it shows evi— dence of wear and may have been derived from a higher horizon. A single specimen from Guam from the Mariana Limestone at USGS locality 20600; age, probably Pleistocene. Rissoina (Schwartziella) aff. R. indrai Beets Plate 12, figures 23, 24 Large, stout; about seven gently convex whorls with a slight suggestion of a shoulder; suture moderately im- pressed; aperture lenticular, posterior channel narrow and shallow, anterior channel broad and deep, peristome heavily callused, outer lip thickened and extended for- ward. Sculpture consisting of slightly curved axial ribs and spiral threads. Ribs are coarse on early whorls but become smaller and more numerous on later whorls (about 40 on penultimate whorl, about 50 on body whorl) ; spiral threads become increasingly prominent on later whorls as ribs decrease in size; on last two whorls, ribs are beaded by spirals; on base of body whorl and on thickened exterior of outer lip, the spirals dominate axial ribs. PALEONTOLOGY Measurements of the figured specimen, USNM 648383: height 7.7 mm, diameter 3.1 nnn. The Eniwetok fossil appears to differ from the Borneo form in that the whorls have a slight shoulder, whereas in the Borneo fossils the whorls are thickest near the base. Occurrence: A single specimen from drill hole F—I, Eniwetok Atoll, at a depth of 930—940 feet; early Miocene (Tertiary f). R. indraf was described by Beets (1941, p. 23, pl. 1, figs. 4448, 52-56l from the Miocene (Tertiary fl of eastern Borneo. Two incomplete specimens from younger (Tertiary g) beds in drill hole F—l (690—700 ft) and K—IB (758—768 ft) may represent this species. Both are smaller than the figured specimen and are more coarsely ribbed, the discrepancy in size between the ribs on the early whorls and those of the later whorls being much less marked than in the figured specimen. Rissoina (Schwartziella) mejilana Ladd, n. sp. Plate 12, figures 25, 26 Small, short, stout; about 11/2 smooth convex whorls forming protoconch, followed by five sculptured gently convex whorls; suture impressed; aperture lenticular, posterior angle acute, anterior channel broad and moder- ately deep; peristome callused, edge of outer lip thin but thickened behind to form a low varix. Sculpture consist- ing of weak to moderately strong axial ribs, 23 or more on body whorl; fine spiral threads are on the lower part of body whorl but visible only under high magnification. Measurements of the holotype (K—IB, Eniwetok, 831— 842 ft), USNM 648384: height 2.8 111111, diameter 1.1 mm. Characterized particularly by its short stout form and numerous axial ribs. Occurrence: Four specimens from three deep holes on Eniwetok at depths of 800—990 feet; age, early Miocene (Tertiary f). Rissoina (Schwartziella) jirikana Ladd, n. sp. Plate 12, figures 27, 28 Very small, stout; two smooth gently convex whorls form protoeonch, followed by 31,/f; sculptured whorls like— wise of slight convexity; suture deeply impressed; aper- ture lenticular, posterior angle acute, anterior channel broad and moderately deep; inner lip heavily callused; edge of outer lip thin but thickened behind to form a low varix. Sculpture consisting of weak widely spaced axial ribs. Measurements of the holotype (213, Bikini, 1,440—1,451 ft), USNM 648385: height 2.3 mm, diameter 0.9 mm. This Schwartziella is smaller than S. mejilana from younger Miocene beds at Eniwetok, has fewer whorls, fewer axial ribs, and a more deeply impressed suture. 67 Occurrence: Two specimens from drill hole 2B, Bikini Atoll, at a depth of 1,419—1,451 feet; age, early Miocene (Tertiary e). Rissoina (Schwartziella) rilebana Ladd, n. sp. Plate 12, figures 29, 30 Small, pupoid, thick; protoconch of three smooth con- vex whorls followed by five gently convex sculptured whorls; suture obscure; aperture ovate, posterior angle acute, anterior channel broad and moderately deep, peristome callused, outer lip thickened externally. Sculp- ture consisting of 12 strong widely spaced continuous axial ribs. Measurements of the holotype (2B, Bikini, 778—789 ft) USNM 648386: height 3.1 111111, diameter 1.3 mm. Characterized particularly by its pupoid form and con- tinuous axial ribs. R. rilebana appears to be very closely related to R. triticca Pease, a Recent species known from Hawaii and many parts of the IndoePacific, but that species is less pupiform and has a more clearly exposed suture. Occurrence: ’I‘wo specimens from drill hole 2B, Bikini Atoll, at a depth of 778—831 feet; age, late Miocene (Tertiary g). Subgenus ZEBINELLA Mérch Merch, 1876, Malakozoologische Blatter, v. 23, p. 47. 'Type (by subsequent designation, Nevill, 1885, Hand list Mollusca Indian Mus, pt. 2, p. 73, 87): Rissoz'na decussata (Montagu) [Helix]. Recent, West Indies. Includes species with fine axial ribs and spiral threads; outer lip thickened into a varix and extended forward; anterior channel shallow, only slightly undercutting columella. Rissoina (Zebinella) emnanana Ladd, n. sp. Plate 12, figures 31, 32 Medium in size, moderately slender; protoconch of three smooth convex whorls followed by about six in- flated whorls; suture impressed; aperture semicircular; posterior channel narrow and deep; anterior channel broad, slightly undercutting the callus of the inner lip; outer lip moderately thickened, extended slightly forward and flaring. Sculpture consisting of close—set oblique axial ribs that are slightly more prominent on the spire than on the body whorl; between axials are numerous fine spiral threads. Measurements of the holotype (E—l, 1,010—1,020 ft), USNM 648387: height 4.8 mm, diameter 2.1 mm. B. emnanana is characterized particularly by its in- flated whorls and impressed suture; it differs in these features from the West Indian type species R. decussata 68 (Montagu) and from other Zcbinellas from the Marshall Islands. Occurrence: In drill holes E—l and K—1B, Eniwetok Atoll, at depths of 620-1,020 feet (total of nine speci- mens) ; age, Miocene (Tertiary f and g). Rissoina (Zebinella) tenuistriata Pease Plate 12, figures 33, 34 Rissoina tenuistriata Pease, 1867, Am. Jour. Conchology, v. 3, p. 295, pl. 24, fig. 30. Tryon, 1887, Manual Conchology, v. 9, p. 386, pl. 58, fig. 24. Medium in size, slender; protoconch of about 21/2 un— marked convex whorls followed by six gently convex whorls; suture lightly impressed; aperture lenticular, posterior channel narrow and deep, anterior channel broad and shallow, slightly undercutting the callus of the inner lip. Outer lip thickened and extended forward. Sculpture consisting of close-set slightly curved axial ribs, which become Obsolete on the lower half of the body whorl, and fine spiral threads. Measurements of the holotype En—4, Eniwetok, 51/2 ft, USNM 648388: height 5.5 mm, diameter 2.3 mm. Occurrence: Eighteen specimens from several drill holes on Eniwetok Atoll from near the surface to 30 feet; rare at greater depths to 915 feet; a single specimen from drill hole 2A on Bikini, depth 306—310 feet (Post— Miocene). Age, Recent to early Miocene (Tertiary f). The Miocene specimens are smaller than the Recent shells. R. tenuistriata, first described from the Tuamotu [Paumotul Islands, is now recognized in many parts of the Indo-Pacific. Rissoina (Zebinella) aff. R, supracostata Garrett Plate 12, figures 35, 36 Large, moderately slender; whorls, exclusive of proto- conch; about seven uniformly convex; suture impressed; aperture large, broadly lenticular; inner lip callused, outer lip thickened; siphonal fasciole low, smooth. Sculp— ture consisting of slightly oblique axial ribs on upper whorls of spire and fine close-set spiral striae over all whorls. Figured specimen, USNM 648389: height (without protoconch) 12.4 mm, diameter 2.9 mm. Occurrence: A single specimen from drill hole E—1 on Eniwetok, depth 890«900 feet; age, early Miocene, Ter— tiary f. The large shell probably represents an unde- scribed species, but a name is withheld pending better type material. Reseinbles R. supracostata, a Recent species described by Garrett (1873, p. 209) from Fiji, but in that species CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS the whorls of the spire are distinctly turreted and the shell has a more elevated siphonal fasciole. Subgenus PHOSINELLA Mérch Miirch, Malakozoologische Blateer, v. 23. p. 51. Type (by subsequent designation, Nevill, 1885, Hand list Mollusca Indian Mus, pt. 2, p. 73, 83): Rissoa pulchrd C. B. Adams. Recent. West Indies. Includes species with strong reticulate sculpture, a dis- tinct siphonal fasciole, and an anterior channel that is broad and deep. Rissoina (Phosinella) clathrata A. Adams Plate 12, figure 37; plate 13, figures 1,2 Rissoina clathrata A. Adams, 1851, Z001. Soc. London Proc., p. 265. Tryon, 1887, Manual Conchology 9, p. 381, pl. 57, fig. 79. Riseoina (Phosinella) clathrata A. Adams, Abrard, 1946, Annales de paléontologie, v. 32, p. 54, pt. 4, fig. 17. Medium in size, stout; about eight gently convex whorls; aperture broadly lenticular, extended forward below; posterior angle slightly less than 90°; outer lip with a strong varix; anterior channel broad and deep. Sculpture reticulate; axial ribs (about 17 on last whorl) crossed by spiral ribs (5 on last whorl), most of which are stronger than axial ribs; intersections beaded; siphonal fasciole heavy and beaded, separated from the lowest spiral rib by a prominent sulcus. Measurements of the New Hebrides specimen (pl. 12, fig. 37): height (incomplete) 8.7 mm, diameter 3.6 mm. The figured Fijian shell (pl. 13, figs. 1, 2), USNM 648-391: height 7.2 mm, diameter 2.6 mm. Occurrence: Island of Malekula, New Hebrides, in beds of Pliocene age; four specimens from Viti Levu, Fiji (stas. 160, 160A, and FB—20) in the Suva Formation of Miocene age (Tertiary f). Living shells have been re- ported from the Philippines, Australia, Singapore, and the Red Sea; rare in the Marshall Islands. R. clathrata appears to be a somewhat variable species. The two Fijian fossils are worn and are smaller than the New Hebrides fossil and Recent shells. Rissoina (Phosinella) briggsi Ladd, n. sp. Plate 13, figures 3, 4 Small, slender; protoconch of two smooth whorls fol- lowed by about six sculptured whorls; aperture semi- circular, inner lip slightly curved, posterior angle sharp, outer lip broadly rounded with a prominent varix; an- terior channel broad and moderately deep. Sculpture sharply reticulate; strong axial ribs (13 on last whorl) crossing almost equally prominent spiral ribs (4 on last whorl); intersections beaded; siphonal fasciole strongly PALEONTOLOGY beaded, separated from the spiral ribs by a broad deep sulcus. Measurements of holotype (Palau, USGS 21301). USNM 648390: height 4.3 mm, diameter 1.8 mm. R. briggsi is similar to R. clathrata A. Adams, a larger Recent Indo-Pacific species also known from the Pliocene of the New Hebrides and the Miocene of Fiji. R. briggsi has fewer and sharper axial and spiral ribs than does R. clathrata. Occurrence: Abundant in the late Miocene (Tertiary g) inarls at the base of the Palau Limestone, northwest of Goikul, Babelthuap Island, Palau. (USGS 21301, 21304). Rissoina (Phosinella) balteata Pease Plate 13, figures 5—8 Rissoz‘uu. bulleata Pease, 1869, Am. Jour. Conehology. v. 5. p. 72. Rissoina multozona Tomlin, 1915, Jour. Conchology, v. 14, p. 321. Small, slender, sides of spire nearly flat; protoconch of two smooth whorls followed by about six sculptured whorls; early whorls flat sided, ultimate and penultimate whorls may be gently convex; suture impressed; aperture small, lenticular with three (rarely four or five) low nodes inside outer lip; anterior channel narrow, moder- ately deep; outer lip varicose behind peristonie. Sculp- ture consisting of fairly close-set axial ribs (about 19 on body whorl), crossed by slightly less conspicuous spiral ribs (about 7 on body whorll; rib intersections beaded; siphonal fasciole with fine close-set spirals. Figured specimen shows a yellow spiral band immediately above the suture (a similar band on living shells is reddish brown). Measurements of the figured specimen (pl. 13, figs. 5, 6) from Recent sediment (drill hole 2, Bikini, 38—40 ft), USNM 648394: height 3.7 mm, diameter 1.4 mm; (pl. 13, figs. 7, 8) from Tertiary] (drill hole E—l, Eniwetok, 880—890 ft), USNM 648395: height 3.7 mm, diameter 1.4 mm. Occurrence: In many drill holes on Bikini and Eni- wetok Atolls, from surface to 1,541 feet (70 lots totaling some 200 speeimensl; ago, Recent to early Miocene (Tertiary el. The Tertiary specimens seem, on the aver- age, to have less well-developmi spiral sculpture, flatter sides, and larger apertures, but these features are vari- able. Pease described the Recent shell from Hawaii where it occurs in great. abundance. Living examples are rare in the Marshall Islands; also know from Tahiti in the Society Islands. As pointed out by Tomlin, this species may be identi- cal with the Recent shell described by Pease as Rissoina costulata from the Tuamotu [Paumotu] Islands. The very small aperture noted by Pease is certainly sugges- 69 tive, but Pease located the brown band on the middle of the whorls. R. cerithiformis Dunker, a Recent species reported from the Red Sea to Hawaii, apparently is iden- tical with R. balteata. Rissoina (Phosinella) bikiniensis Ladd, n. sp. Plate 13, figures 9, 10, 17, 18 Medium in size, slender, protoconch of three smooth whorls, the lowest of which is convex; seven or eight subsequent whorls all flattened; suture impressed; aper- ture broadly lenticular with three or four rounded nodes inside outer lip; posterior angle acute, anterior channel narrow and deep; outer lip slightly or moderately vari- cose. Sculpture consisting of strong axial ribs (about 23 on body whorl) crossed by broad close-set spirals (9 on the body whorl, 4 on penultimate whorl) that form beads on axial ribs. Spiral sculpture not equally developed on all specimens. Measurements of the holotype (2A, Bikini, 1,056— 1,063 ft), USNM 648396: height 4.9 mm, diameter 1.6 mm. Paratype (E—l, Eniwetok, 1,746—1,777 ft), USNM 648400: height 3.6 mm, diameter 1.4 mm. The Eniwetok specimens have a mode deeply impressed suture and a more prominent siphonal fasciole than those from Bikini, and they lack apertural nodes. They may represent a distinct species. R. bikiniensis is larger but more slender than R. balteata Pease; it has more numerous whorls and a deeper anterior channel. Occurrence: Three specimens from Miocene beds in drill hole 2A on Bikini Atoll: one from a depth of 490 feet (core) is Tertiary g; two others from cuttings at lower levels (1,030—1,063 ft) are referred to Tertiary f. Three specimens from drill hole E—1, Eniwetok are from Tertiary f (9604970 ft) and Tertiary e (1,746—1,777 ft). Rissoina (Phosinella) transenna Watson Plate 13, figures 11, 12 Rissoina transemia Watson, 1886, Challenger Rept., v. 15, p. 620, pl. 46, fig. 10. Tryon, 1887, Manual Conchology, v. 9, p. 382, pl. 58, fig. 10. Small, slender, stout; protoconch of about two smooth convex glassy whorls followed by six sculptured whorls; aperture lenticular, posterior angle acute, anterior chan- nel broad and deep, outer lip thickened into a heavy varix. Sculpture reticulate, strong axial ribs (about 16 on last whorll' crossed by equally prominent spirals of which there are 7 or 8 on the body whorl (lowest one on some specimens smaller than others) and 4 or 5 exposed on the penultimate whorl, all intersections beaded; siphonal fasciole heavy and conspicuously beaded. 70 Measurements of the figured specimen (hole Mu—4, Eniwetok Atoll, at 40 ft), USNM 648397: height 3.6 mm, diameter 1.5 mm. Occurrence: In drill holes on Eniwetok (46 specimens) and Bikini (6 specimens) from near the surface to a depth of 873 feet; age, Recent to early Miocene (Tertiary f). The fossils placed here are somewhat variable. Many Specimens from levels below 200 feet have fewer axial ribs. They do not show the subsutural threadlet described by Watson on the type specimen, 3 Recent shell from Fiji. Rissoina (Phosinella) alexisi Ladd, n. sp. Plate 13, figures 13—16 Small, stout; protoeonch of 21/3—3 smooth convex whorls followed by about five sculptured whorls that may be slightly turreted; suture deeply impressed, aper- ture broadly lenticular, posterior angle acute, anterior channel broad and moderately deep, outer lip thickened. Sculpture reticulate, strong axial ribs (13—15 on last whorl) crossed by weaker spirals (5—6 011 last whorl), intersections beaded; siphonal fasciolc moderately strong, beaded. Measurements of the holotype, USNM 648398: height 2.7 mm, diameter 1.1 mm. Paratype, USNM 648399: height 2.5 mm, diameter 1.0 mm. Occurrence: Holotype from drill hole F—l, Eniwetok Atoll, at depth of 1,110—1,120 feet. Paratype A from same hole at depth of 1,100—1,110 feet; both early Miocene ('l‘ertiary 6). Two other specimens recovered from K4113 at depths of 863—1,000 feet; age, Tertiary f. Subgenus RISSOINA 5.5. Type (by monotypy): Rissoina inca d’Orbigny. Re- cent, Pacific coast of South America. Includes species with heavy axial ribs and fine spiral threads; the outer lip is thickened; a siphonal fasciole is not developed but the anterior channel deeply undercuts the columella. Rissoina (Rissoina) abbotti Ladd, n. sp. Plate 13, figures 19—21 Small to medium in size, stout; protoconch not pre- served; about seven subsequent whorls, gently convex, suture impressed; aperture irregularly lenticular; pos- terior channel narrow; anterior channel broad and deep, undercutting the base of the columella; peristorne heavily callused, outer lip thickened. Sculpture consisting of numerous curved axial ribs (25 or more on last whorl). crossed by fine close-set spirals; on lower half of body whorl the intersections are conspicuously beaded. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Measurements of the holotype (drill hole 2A, Bikini, 1,061—1,067 ft), USNM 648371: height (protoconch miss- ing) 4.9 111111, diameter 2.1 mm. Measurements of the paratype (Palau, USGS 21301) USNM 648372: height (protoconeh missing) 8.1 mm, diameter 3.0 mm. Characterized particularly by its strong curved axial ribs and well-developed spiral striae. The single speci- men from Palau is larger than the Marshall Island speci- mens, but in all other respects it is identical with them. Occurrence: Two specimens from drill hole 2A, Bikini Atoll, at depths of 956-1,067 feet (Miocene, Tertiary f and g); six specimens from drill holes F—l and K—lB, Eniwetok Atoll, at depths of 790-963 feet (Miocene, Tertiary f and g); one specimen from the marl at the base of the Palau Limestone northwest of Goikul, Babel- thuap, Palau (USGS 21301) ; (late Miocene, Tertiary g). Rissoina (Rissoina) mijana Ladd, n. sp. Plate 13, figures 22—25 Medium in size with short spire and large body whorl; about five gently convex whorls but may be flattened near suture which is but little impressed; aperture broadly lenticular, posterior channel shallow, anterior channel broad and moderately deep, undercutting the columella; outer lip thickened. Sculpture consisting of moderately strong curved axial ribs and numerous spiral threads, which are most conspicuous on lower half of body whorl. Axial ribs smaller and more numerous on the body whorl than on earlier whorls (about 30 on body whorl, 22 or more on penultimate whorl). Measurements of the holotype (pl. 13, figs. 24, 25), USNM 648374: height (incomplete) 4.3 mm, diameter 1.8 mm. Occurrence: Holotype from drill hole E—l on Eniwetok Atoll at a depth of 880—890 feet; another specimen from 15-1 at depth of 890—900 feet; a third specimen was ob- tained from drill hole 2A on Bikini at 1,040—1,046 feet; age of all three early Miocene (Tertiary f). A specimen from beds of the same age in K—lB (pl. 13, figs. 22, 23) is assigned R. ml'jana with reservations. It is more slender than the other specimens and has flatter whorls and more numerous axial ribs. Rissoina (Rissoina) ailinana Ladd, n. sp. Plate 13, figure 26 Small, stout; protoconeh of two smooth strongly con- vex whorls; four to five slightly convex subsequent whorls; aperture broadly lenticular, posterior angle acute, anterior channel moderately wide and deep, undercutting the columella; outer lip thickened without and heavily callused within, the callus rising to form a low protuber- ance near the posterior angle. Sculpture consisting of PALEONTOLOGY about 20 strong axial ribs 011 body whorl and fine spiral lines that are visible only under magnification. Measurements of the holotype (E—l, Eniwetok, 1,925— 1,955 ft), USNM 648375: height 3.0 mm, diameter 1.3 nnn. R. ai'linana is characterized particularly by the small nmnber of post-nuclear whorls (four to fivel and by the low knob of callus inside the outer lip near the posterior angle, Occurrence: In drill holes F—l, and E—1 on Eniwetok Atoll at depths of 1,925—2,720 feet (10 specimens) and in drill hole 2B on Bikini at 1,724—1,975 feet (3 speci— mensl ; all occurrences early Miocene (Tertiary e). Rissoina (Rissoina) lomaloana Ladd, n. sp. Plate 13, figures 27, 28 Small, moderately slender; protoconch of two smooth convex whorls followed by about six gently convex subse- quent whorls; suture but little impressed; aperture semi- circular, posterior angle acute; anterior channel moder- ately deep, undercutting the base of the columella; inner lip callused, outer lip callused within and thickened into a varix immediately behind the peristome. Sculpture consisting of close—set axial ribs (about 29 on body whorll and numerous fine spiral lines. Measurements of the holotype (drill hole K—lB, Eni- wetok, 842~852 ft l, USNM 648376: height 4.1 mm, diam- eter 1.5 mm. Occurrence: Seven specimens from two deep drill holes on Eniwctok Atoll at depths of 695—890 feet; single speci— men in drill hole 2A on Bikini at 978—988 feet; age, Miocene (Tertiary f—g), Rissoina (Rissoina) goikulensis Ladd, n. sp. Blate 13, figure .29 Small, stout; protoconch of two smooth convex whorls followed by about six gently convex sculptured whorls; suture strongly impressed; aperture broadly lenticular; posterior angle rounded, anterior channel shallow; outer lip slightly thickened with low nodes inside. Sculpture consisting of 20 narrow axial ribs on last whorl, crossed by a few spirals on lower half of body whorl. Measurements of the holotype, USNM 648377: height 3.7 nnn, diameter 1.3 mm. B. goikulensfs resembles R. ailinana from the early Miocene of Bikini and Eniwetok but has more numerous whorls, a more sharply incised suture, and a shallower anterior channel. Occurrence: Three specimens from the marl at the base of the Palau Limestone on Goikul Peninsula, Babel— thuap Island. Palau (USGS 213041; age, late Miocene (Tertiary g). 71 Rissoina (Rissoina) waluensis Ladd, n. sp. Plate 13, figure 30 Small, stout; protoconch of about three smooth con- vex whorls followed by about six flat-sided sculptured whorls; suture impressed; aperture lenticular, posterior angle acute; anterior channel broad and moderately deep, undercutting the columella; outer lip with tw0 obscure elongate nodes within, slightly thickened behind. Sculp- ' ture consisting of about 20 slightly oblique axial ribs on the last whorl, crossed by a few spirals; intersections beaded. Measurements of the holotype, USNM 648378: height 3.8 mm, diameter 1.5 nnn. R. Imluensis has whorls that°are more flat sided than those of R. ailinana from the early Miocene of Bikini and I‘lniwetok, and it has stronger spiral sculpture than that species. ()ceurrence: Holotype and four other worn specimens from conglomerate layer at base of reef limestone in Suva Formation, Walu Bay, Suva, Fiji (sta. 160). Para- type and two other specimens from FB—20 (Virtually same locality as sta. 160); age, early Miocene (Tertiary fl. Rissoina (Rissoina) ekkanana Ladd, n. sp. Plate 13, figures 31, 32 Small, slender; protoconch of 11/2 smooth bulbous whorls coiled at an angle with the axis of the spire and about six sculptured gently convex subsequent whorls; suture impressed; aperture lenticular, posterior angle acute, anterior channel broad and moderately deep, slightly undercutting the columella; edge of outer lip thin but thickened slightly behind. Sculpture consisting of strong widely spaced axial ribs, about 14 on body whorl, and spiral lines that are especially prominent on the lower part of the last whorl. Measurements of the holotype, USNM 648379: height 3.2 mm, diameter 1.2 111111. Occurrence: Forty eight shells from five drill holes on Iflniwetok Atoll at depths to 110 feet (holotype from Mix—4 at 35 ft) ; age, Recent. Rissoina (Rissoina) ambigua (Gould) Plate 14, figures 23, 24 Pyramidella ambigua Gould, 1849, Boston Soc. Nat. History Proc. v. 3, p. 118 [1851]. Johnson, 1964, US. Natl. Mus. Bull. 239, p. 39. Rissoa ambigua Gould, 1852, US. Explor. Exped., Mollusca, p. 217, pl. 15, p1. 261a—c. Rissoina ambigua (Gould), Tryon, 1887, Manual Conchology, v. 9, p. 371, pl. 55, figs. 27, 29, 31, 35; pl. 54, fig. 7. Hedley. 1899. Australian Mus. Mem. 3, pt. 7. p. 422. Rissoina maten'nsulae Pilsbry, 1904, Acad. Nat. Sci. Philadelphia Proc., p. 27, pl. 5, figs. 43, 43a. 72 CHITONs AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Large, elongate-conic, thick, milk white; protoconch of 21/2 rounded smooth whorls; seven subsequent whorls, those above the body whorl showing a weak shoulder immediately below the suture; body whorl flattened, suture impressed. Aperture irregularly lenticular, inner lip concave, anterior channel deep, undercutting co- lumella to form a rounded toothlike projection, outer lip thickened. Sculpture consisting of fine close—set axial ribs (more than 20 on body whorl, including 3 on thick- ened outer lip) and weak spirals that are limited to the base of the body whorl, below the posterior angle of the aperture. Measurements of the figured specimen, USNM 648423 (Recent, Rujiyoru, Eniwetok): height 6.4 mm, diameter 2.3 mm. A fossil specimen from hole 1, Bikini, 5—10 feet, USNM 648424: height 6.4 mm, diameter 2.2 mm. R. ambigua is characterized particularly by its elon- gate-conic form. Occurrence: Originally described from the Tuamotu [Paumotu] Islands but later widely reported from the Indo-Pacific (Hawaii, Ellice Islands, Society Islands, Fiji, New Caledonia, New Guinea, Singapore, Ceylon, Mauritius, and Japan). Figured specimen and one other Recent shell from the island of Rujiyoru, Eniwetok Atoll. Recent shells were also collected at other local- itics on Eniwetok and on the nearby atolls of Bikini, Rongerik, and Rongelap. Three fossil specimens were found in shallow drill holes on Eniwetok and Bikini at depths to 10 feet; all Recent in age. Rissoina (Rissoina) ambigua parryensis Ladd, n. subsp. Plate 14, figures 25, 26 Large, elongate—conic, thick, whorls flattened; proto- conch consisting. of about two smooth whorls; seven sub- sequent whorls; suture not impressed. Aperture subsemi- circular, inner lip concave, anterior channel deep, under- cutting columella to form a rounded toothlike projection, outer lip thickened. Axial sculpture consisting of fine close-set ribs (37 on body whorl) ; spiral sculpture absent. Measurements of the holotype, USNM 648425: height (protoconch incomplete) 6.8 mm, diameter 2.3 mm. R. ambigua parryensis may be ancestral to the Recent shell. The new subspecies has more numerous axial ribs, lacks spiral sculpture, and its suture is less impressed. ,Occurrence: Single specimen from drill hole E—l, Eni- wetok, at depth of 620—630 feet in beds referred to late Miocene (Tertiary g). Rissoina (Rissoina) concinna A. Adams Plate 13, figure 33 Rissoina concimm A. Adams, 1851, Zool. Soc. London Proc., p. 266. Tryon, 1887, Manual Conchology 9, p. 386, pl. 58, fig. 18. Medium in size, slender, thick; protoconch not pre- served; about six subsequent whorls, the earlier ones flattened, the later ones slightly convex; suture impressed; aperture semicircular, posterior angle acute, excavated to form a shallow channel; anterior channel broad and fairly deep, undercutting the columella; inner and outer lips heavily callused, outer lip thickened. Sculpture con- sisting of prominent slightly oblique axial ribs (about 29 on body whorl) ; fine spiral lines are limited to the lower part of the body whorl near the aperture. Measurements of the figured specimen (drill hole E—l, Eniwetok, 970—980 ft) USNM 648380: height (incom- plete) 6.4 mm, diameter 2.3 mm. Occurrence: Two specimens from deep drill holes on Eniwetok at depths of 970—980 feet in beds referred to Miocene (Tertiary f). In drill hole 2A on Bikini, a single specimen from a depth of 852—857 feet; age late Miocene (Tertiary g); a single specimen from 2B at a depth of 1,020—1,100 feet is early Miocene in age (Tertiary f); one from 1,671—1,682 feet is in beds referred to Tertiary e. The Recent shells deScribed by Adams were collected in the Philippines. Rissoina (Rissoina) sp. A Plate 13, figures 34, 35 A single imperfect specimen of a distinctive species of Rissoina s.s. was collected from the Suva Formation in its type section on ,Walu Bay, Fiji (sta. 160); age Miocene (Tertiary f). The shell differs from other fossil Rissoinas from the island area in that its flattened whorls and unimpressed suture give the spire an overall convex outline. The narrow close—set ribs of each whorl are alined with those of the adjoining whorl; about 30 ribs are on the last whorl, 25 on the penultimate. Meas- urements of the single specimen, USNM 648381: height (apex missing) 4.8 mm, diameter 1.7 mm. Rissoina sp. A resembles Rissoina concinna from beds of about the same age in the Marshall Islands, but its axial ribs are more nearly vertical, and it lacks spiral sculpture. Subgenus RISSOLINA Gould Gould, 1861, Boston Soc. Nat. History Proc., v. 7, p. 401. Type (by subsequent designation, Nevill, 1885, Hand list Mollusca Indian Mus, pt. 2, p. 73, 77) Rissoina pli- catula Gould, Recent, western Pacific. Characterized particularly by a strong siphonal fas— ciole. Rissoina (Rissolina) turricula Pease Plate 13, figures 36, 37 Rissoina turricula Pease, 1860, Z00]. Soc. London Proc., p. 438. Tryon, 1887, Manual Conchology, v. 9, p. 377, pl. 56, fig. 63. PALEONTOLOGY Small, stout, whorls convex, distinctly angled above; aperture ovate, slightly flattened below; anterior chan- nel broad and deep; sculpture consisting of strong axial ribs, 11 or 12 on body whorl; spaces between ribs finely striate. Measurements of figured specimen (F—l, Eniwetok, 20—45 ft), USNM 648407: height 2.7 mm, diameter 1.0 mm. Occurrence: Nine specimens from Recent sediments in six drill holes at Eniwetok; greatest depth, 70—80 feet in hole E—1 on Parry Island; figured specimen from depth of 20—45 feet in hole F—1 on Elugelab; a single specimen from drill hole K—1B at depth of 968-978 feet is from early Miocene (Tertiary f); a broken but otherwise fresh-looking specimen from drill hole 2B on Bikini at a depth of 1,335—1,345 feet (Tertiary 6) may have been derived from a higher level; four specimens were col— lectcd from the Suva Formation, Viti Levu, Fiji (sta. FB-20); age, Miocene (Tertiary f) and one from the, Ndalithoni Limestone, Vanua Mbalavu, Fiji (sta. 110B) ; age, probably Pliocene (Tertiary h). 73 The species was originally described as a Recent shell from Hawaii; later reported from Fiji, Ceylon, and Mauritius; also found at Bikini (reef-flat drift) and other atolls in the northern Marshalls by J. P. E. Morri- son. Rissoina (Rissolina) marshallensis Ladd, n. sp. Plate 13, figures 38—40; Plate 14, figures 1—4 Small to medium, robust; protoconch of two smooth convex whorls followed by five to six sculptured whorls that are uniformly convex or slightly angled above; aperture subsemicircular, inner lip gently convex, outer lip thickened, posterior angle acute, anterior channel broad and moderately deep. Sculpture consisting of strong axial ribs (12—19 on body whorl) separated by wide interspaees that may be nearly smooth or heavily striate. Siphonal fasciole conspicuously beaded; on some shells it is sharply elevated, on others it is not distinctly set off from the remainder of the whorl. The measurements of the holotype and five paratypes selected to illustrate the variation in size, profile of whorls, development of siphonal fasciole, and spiral sculpture, are given in the following table. Specimen Drill Depth Height Dia— Profile Siphonal Spiral hole (feet) (mm) meter of whorls fasciole threads (mm) Holotype USNM 648408 _________ K—lB 8944905 5.0 1.9 Slightlyi Strong Weak. turrete . Paratype A, USNM 648409 _______ 113—1 850—860 13.8 1.5 Strongly _ _ _ -do- _ _ _ Absent. turreted. Paratype B, USNM 648410 _______ KelB 1,049—1,060 7.4 2.7 Not d _ - _ _do- _ - _ Strong turrete . Paratype C, USNM 648411 _______ K—IB 842-852 4.2 1.6 Slightlyi Weak _ _ _ _do_ _ turrete . Paratype D, USNM 648412 _______ K—1B 936—947 3.8 1.5 _ - - _do_ _ _ _ _ - _ .do- _ _ _ Weak Paratype E, USNM (348413 _______ 2B 1,020—1,100 5.2 2.1 Not _ _ _ _do_ - _ _ Strong turreted. ‘ Incomplete. R. marshallensis appears to be an exceedingly variable species. It is closely related to the Recent R. turricula Pease but is larger, has sharper and (on the average) more numerous ribs. R. turricula may have developed from R. marshallensis; in drill holes on Eniwetok where both occur there is a stratigraphic gap of nearly 600 feet between known occurrences of the two. R. semari Beets from the late Miocene of East Borneo is larger than the Marshall Island fossil and does not have a strongly beaded siphonal fasciole. Occurrence: An abundant species in the Miocene beds beneath Eniwetok and Bikini. Sixty—one lots were re- covered from cuttings in three drill holes on Eniwetok (E—J, F—l, K—IB) at depths of 620—1,715 feet; age, Tertiary e—g. Nine lots were collected from two drill holes on Bikini (2A and 2B ) at depths of 904—1,088 feet; Tertiary f—g. (One Bikini specimen from core at 936 ft). Rissoina (Rissolina) ephamilla Watson Plate 14, figures 5—8, 11, 12 Rissmna ephamilla Watson, 1886, Challenger Rept. 15, p. 617 [R. scalan'fm'mis], p. 719, pl. 46, fig. 6. Rissoina scalariformis Watson, Tryon, 1887, Manual Conchology, 9, p. 378, pl. 54, fig. 1. Very small, slender, polished; protoconch of 2% whorls; later whorls about 5, uniformly convex or tur- reted; aperture semilunate, outer lip oblique with thick varix; siphonal fasciole heavy and beaded; anterior chan- 74 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS nel broad and shallow. Sculpture consisting of strong slightly oblique axial ribs (12—16 on last whorl), the spaces between smoothly polished or showing faint traces of spiral striae. Measurements of figured specimen from Eniwetok (pl. 14, figs. 5, 6) USNM 648414: height 3.0 mm, diameter 1.2mm. Figured specimen from Bikini (pl. 14, figs. 7, 8), USNM 648415: height 2.9 mm, diameter 1.1 mm. An unusually slender specimen from Eniwetok (pl. 14, figs. 11, 12) USNM 648417: height 3.0 mm, diameter 0.8 mm. Easily distinguished by its slenderness from most other species of Rissolina in the Marshall Island area. Occurrence: In all three deep holes on Eniwetok (30 specimens) at depths of 212—1,029 feet; age, Recent to early Miocene (Tertiary f); a single Recent specimen was also recovered from one of the shallow holes on Eni- wetok (Mu—4) from a depth of 26—27 feet. Two speci- mens from hole 2B on Bikini Atoll at a depth of 447—464 feet are post-Miocene in age. The Recent shells de- scribed by Watson were collected from the reefs off Honolulu at a depth of 40 fathoms. Rissoina (Rissolina) kickarayana Ladd, n. sp. Plate 14, figures 9, 10 Small, slender; protoconch of two smooth whorls suc- ceeded by about six gently convex slightly turreted and strongly ribbed later whorls; aperture semilunate, outer lip extended forward immediately above base and bordered by a heavy varix; siphonal fasciole incon— spicuously beaded by extensions of axial ribs of body whorl; anterior channel broad and shallow. Sculpture consisting of strong erect slightly oblique axial ribs, 9—11 on body whorl. Measurements of the holotype (USGS 21301), USNM 648416: height 4.1 mm, diameter 1.5 mm. R. kickarayana is smaller and more slender than R. marshallensis, from the Miocene of the Marshalls; its axial ribs are more oblique and fewer in number. Occurrence: In the late Miocene marls at the base of the Palau Limestone near Goikul, Babelthuap Island, Palau (in great abundance at USGS 21301 and 21304; single specimen at 21308). Rissoina (Rissolina) herringi Ladd, n. sp. Plate 14, figures 13, 14 Small, slender; protoconch of smooth convex whorls, coiled at a slight angle to the axis of the spire, followed by 61/2 gently convex sculptured whorls; aperture len- ticular, posterior angle acute, anterior channel broad and moderately deep, slightly undercutting the columella; outer lip thickened. Sculpture consisting of axial ribs (about 20 on last whorl) and fine spiral striae; spirals best developed on flattened triangular area lying ad— jacent to edge of inner lip; siphonal fasciole low, not sharply set off from remainder of whorl. Measurements of the holotype, USNM 648418: height 4.8 mm, diameter 1.8 mm. Occurrence: Four specimens from drill holes F—1 and E—l, Eniwetok Atoll, at depth of 710—860 feet (holotype from F-l, 710—720 ft) ; age, late Miocene (Tertiary g). Rissoina (Rissolina) harti Ladd, n. sp. Plate 14, figures 15, 16 Very small, stout; protoconch of 11/2 smooth convex whorls, followed by about six convex sculptured whorls; body whorl slightly flattened in profile with a weak shoulder that extends forward from the posterior angle of the aperture; suture impressed; aperture broadly len— ticular, p0sterior channel narrow and shallow, anterior channel shallow and indistinct. Sculpture consisting of strong slightly oblique axial ribs, 17—20 on body whorl; spiral striae weakly developed on body whorl; siphonal fasciole low, not sharply set off from rest of whorl. Measurements of the holotype (2B, Bikini, 1,555—1,566 ft) USNM 648419: height 3.2 mm, diameter 1.3 mm. Occurrence: Five specimens from drill hole 2B on Bikini Atoll at a depth of 1,429—1,829 feet; age, early Miocene (Tertiary e). Rissoina (Rissolina) boumeae Ladd, n. sp. Plate 14, figures 17, 18 Small, stout; protoconch of three smooth rounded whorls, followed by about five gently convex weakly shouldered sculptured whorls; aperture lenticular; outer lip thickened and extended forward; posterior angle acute, anterior channel broad, undercutting the columella. Sculpture consisting of strong oblique slightly curved axial ribs, 15—19 on last whorl; siphonal fasciole thick and beaded, separated from the remainder of whorl by a broad depression. Measurements of the holotype from FB—20, USNM 648420: height 3.2 mm, diameter 1.2 mm. R. bourneae resembles R. kickarayana Ladtl, a species of about the same age occurring in Palau, but the Fijian shells are smaller and have more numerous axial ribs. Occurrence: Represented by a dozen specimens from the conglomerate layer at the base of the reef limestone in the Suva Formation, Walu Bay, Suva, Fiji (stas. FB—20 and 160); age, early Miocene (Tertiary f). Rissoina (Rissolina) plicata A. Adams Plate 14, figures 21, 22 Rissaina plicata A. Adams, 1851, Zool. Soc. London Proc., p. 264. Tryon, 1887, Manual Conchology 9, p. 375, pl. 56, figs. 58—60, 68; pl. 54, fig. 8. PALEONTOLOGY Shell large, heavy, thick, with strong widely spaced axial ribs, 10 on the last whorl and fine spiral striae, The siphonal fasciole is heavy, strongly elevated, and is smooth or weakly beaded by the axial ribs. Aperture lenticular, anterior channel broad and fairly deep, undercutting the columella. Measurements of the figured specimen (F—l, Eniwetok, 870—880 ft), USNM 648422: height (apex missing) 6.9 mm, diameter 3.0 mm. Occurrence: Two specimens from drill hole F—l on Eniwetok Atoll at depth of 870—950 feet; age, early Miocene (Tertiary f). Described from Recent shells from Philippines; also known from Samoa, Cook Islands, Fiji, Red Sea, and Mauritius. Rissoina (Rissolina) sp. B Plate 14, figures 19, 20 Small, stout; with strong curved axial ribs, 21 on body whorl; aperture semioval, outer lip thickened, anterior channel broad and deep; spiral striae, weak on early whorls, more prominent on last whorl, dominating the axials on the lower half of that whorl; siphonal fasciole low, faintly beaded. Measurements of the figured specimen, USNM 648421: height (apex missing) 3.9 mm, diameter 1.6 mm. Rissoina (Rissolinalsp. B differs from R. bourneae in that it has stronger spiral sculpture, more strongly curved axial ribs, and a smoother siphonal fasciole. Occurrence: Two incomplete specimens from station 165, west of Nasongo, Viti Levu, Fiji; age, probably Miocene. Genus BARLEEIA W. Clark Clark, 1853, Annals and Mag. Nat. History, 2d set. V. 12, p. 108. Type (by monotypy) : Rissoa rubra A. Adams. Recent, Atlantic. Subgenus BARLEEIA s.s. Minute, smooth, imperforate shells with blunt apex and large body whorl. Barleeia (Barleeia) meiauhana Ladd, n. sp. Plate 14, figure 27 Minute, ovate, apex blunt; about four whorls, inflated, smooth; suture impressed; aperture broadly oval, entire, slightly constricted, narrowed above, broadly rounded below; lips sharp. Measurements of the holotype, USNM 648426: height 0.9 mm, diameter 0.6 mm. B. meiauhana is much smaller and proportionately wider than the type species, B. rubra (Adams). The Palau fossil more closely resembles B. carpenteri Bartsch, 75 a Recent species from Baja California, but that form has flattened slightly shouldered whorls. Occurrence: Seven specimens from late Miocene (Ter- tiary g) marls at base of Palau Limestone on Goikul Peninsula, Babelthuap Island, Palau (USGS 21301). Family ASSIMINEIDAE Genus ASSIMINEA Fleming Fleming, 1828, History of British animals, v. 5, p. 275. Type (by monotypy): Assiminea grayana Fleming. Recent, England. Assiminea nitida eniwetokensis Ladd, n. subsp. Plate 10, figure 8 Small, spire low, apex blunt, robust; four to five whorls, smooth, gently and uniformly convex; suture lightly im- pressed; aperture broadly ovate, peristome not con— tinuous, inner lip callused, slightly flaring below, with a groove behind it in the umbilical region; outer lip thin. The holotype and some other specimens show an obscure thread below the suture. Measurements of the holotype (K—1B, Eniwetok, 831— 842 ft), USNM 648325: height 1.8 mm, diameter 1.3 mm. The Marshall Island fossils have been compared with the cotypes of the Recent A. nitida (Pease, 1864, p. 674, as Hydrocena nitida) from the Society Islands (USNM 591317) and with examples of many of the numerous subspecies that have been recognized from island groups in the southwest Pacific (Abbott, 1958). A. nitida eni- wetokensis is smaller than A. nitida m'tz'da, has fewer whorls, and the base of the body whorl is more uniformly rounded. The fossils have also been compared with the types and other specimens of A. nitida marshallensis Abbott (1958, p. 256) collected at Eniwetok and at other atolls in the Marshall group. The same differences in size and curvature of the body whorl are apparent, and the fossils are proportionately much shorter than adults of the elongate Recent shell. The fossil is represented by a total of 26 specimens all of which are small but some of which certainly are adults. Assiminea m'tz'da eniwetokensis belongs to a group of small amphibious air-breathing snails that has repre- sentatives living in the area today (Abbott, 1958). Occurrence: Twenty-six specimens from deep holes (E—l and K~1B) on Eniwetok Atoll at depths of 710— 842 and 1,835-1,993 feet; and one specimen from Bikini (2B, 1,713—1,724 ft) ; age, Miocene (Tertiary e and g; no specimens recovered from beds assigned to Tertiary I). Family ADEORBIDAE (VITRINELLIDAE) Genus HAPLOCOCHLIAS Carpenter Carpenter, 1864, Annals and Mag. Nat. History, 3d ser., v. 13, p. 476. 76 Type (by inonotypy): Haplocochlias cyclophoreus Carpenter. Recent, west coast of Mexico. Haplocochlias sp. A Plate 14, figures 28, 29 Minute, inflated, naticoid in general outline; aperture subcircular, peristome continuous, outer lip thickened; umbilicus wide, bordered by a smooth ridge. Sculpture consisting of fine spiral striae. Measurements of the figured specimen, USNM 648427: height 1.2 mm, diameter 1.1 min. This rare shell is unusual in that it combines the gen— eral outline of a naticid with a thickened outer lip that is suggestive of a rissoid. The single Eniwetok fossil ap- pears to be closely related to the type species H. cyclo- phoreus Carpenter, a Recent species described from Cabo San Lucas at the southern tip of Baja California and reported also from Bahia Magdalena, 175 miles to the northwest. Carpenter’s type lot of specimens (USNM 18112) contains three large shells (the largest measur- ing 4.5 mm in height and 5.1 mm in diameter) and one minute shell (height 1.3 mm, diameter 1.4 mm) that he regarded as a juvenile. The Eniwetok fossil resembles the smallest specimen in the type lot, but the two are not conspecific because the Recent shell is thicker, more coarsely striated, has a weaker umbilical ridge, and a less well developed varix on the outer lip. It is possible that the minute shell in the type lot is specifically distinct from the larger shells. Occurrence: Single specimen from drill hole K—lB on Eniwetok Atoll at a depth of 831—842 feet; age late Miocene (Tertiary g). Genus LEUCORHYNCHIA Crosse Crosse, 1867, Jour. conchyliologie, 15, p. 319. Type (by monotypy): Leucorhynchia caledonica Crossc. Recent, New Caledonia. Leucorhynchia caledonica Crosse Plate 14, figures 30, 31 Leucorhynchia caledonica Crosse, 1867, Jour. Conchyliologie, V. 15, p. 319. pl. 11, fig. 4. Teinostoma (Leucm'hynchia) caledonicum Crosse, Tryon, 1888, Manual Conchology 10, p. 106, pl. 35, figs. 85, 86. Small, lenticular, smooth, perforate; periphery cari- nate, the carina becoming obsolete near the circular aper- ture; peristome entire, its basal edge extended laterally to form a thick pad of callus that projects over the umbilicus but does not come in contact with it. Measurements of the figured specimen (Eb—2, Eni- wetok, 21—211/2 ft) USNM 648428: height 1.4 mm, diameter 2.5 mm. CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Occurrence: From four drill holes on Eniwetok Atoll, from near the surface to depth of 60 feet (age, Recent) but not found living in the area today. The species was originally described from New Caledonia and has also been reported from Queensland, Australia (Cotton, 1959, p. 204). All six fossil specimens are smaller than the Recent shells from New Caledonia. Leucorhynchia crossei Tryon Plate 14, figures 32, 33 Teiuostoma (Leucorhynchia) crossei Tryon, 1888, Manual Conchology 10, p. 106, pl. 35, figs. 86a, 86b. As noted by Tryon in defining the species, it differs from the genotype L. caledonica only by having a rounded, instead of a carinated, periphery. Measurements of the figured specimen (E—l, Eniwetok, 35—40 ft), USNM 648429: height 1.2 mm, diameter 2.3 mm. Occurrence: From five drill holes on Eniwetok Atoll, from near the surface to depth of 55 feet (age, Recent) but not found living in the area today. Originally de- scribed from Singapore, later reported from northwestern Australia and the Arabian Sea. Represented by 20 fossil specimens from 10 localities and horizons. All the fossils are smaller than the Recent shells but seem not to differ in other respects. L. crossei appears to be very closely related to L. caledonia. The two should, perhaps, be combined though in the Eniwetok drill holes they were not found together in the same sample. Leucorhynchia? stephensoni Ladd, n. sp. Plate 14, figures 34, 35 Minute; spire flattened, body whorl rapidly expanding, periphery broadly angled; perforate; aperture circular; peristome entire; expanded below to form a broad flat- tened callus that extends over the umbilicus and par- tially obscures it. Under magnification the sculpture is seen to consist of fine close—set spiral lines and a ring of short widely separated axial lines radiate from the um- bilicus. Measurements of the holotype, USNM 648430: height 1.0 mm, diameter 2.0 mm. The sculpture and the flattened spire distinguish this species from L. caledoma and L. crosset which occur at higher, levels in Eniwetok drill holes. Occurrence: Holotype, and only specimen, from drill hole K—1B on Eniwetok at a depth of 1,249—1,259 feet in sediments referred to early Miocene (Tertiary e). PALEONTOLOGY Leucorhynchia? lilli Ladd, n. sp. Plate 15, figures 1, 2 Small; spire low, body whorl rapidly expanding, periphery smoothly rounded; aperture circular, slightly constricted; peristome entire; umbilicus wide and deep, partially filled by a broad spiral rib. Sculpture consisting of fine close-set spiral lines over the entire shell, and, on the base, broad widely separated axials that are discer- nible only under magnification. Measurements of the holotype, USNM 648432: height 1.6 mm, diameter 3.1 mm. L.? lz'lli resembles L.? stephensom’ in sculptural fea— tures but has a more elevated spire and lacks the thick pad of callus that partially covers the umbilicus in that species; its reference to Leucorhynchia is even less cer- tain than in the case of L.? step‘hensom'. Occurrence: Single specimen from drill hole 1 on Bikini Atoll at a depth of 40 feet; age, Recent. Genus LOPHOCOCHLIAS Pilsbry Pilsbry, 1921, Acad. Nat. Sci. Philadelphia Proc., p. 377. Type (by monotypyi: Haplocochlias minutissimus Pilsbry. Recent, Hawaii. Lophocochlias minutissimus (Pilsbry) Plate 15, figures 3—5 Haplocochlias (Lophocochlias) minutissimus Pilsbry, 1921, Acad. Nat. Sci. Philadelphia Proc., p. 377. Edmondston, 1946, B. P. Bishop Mus, Spec. Pub. 22, p. 165. Minute, turbinate; apex sharp, made up of smooth whorls; body whorl descending at aperture, bearing six strong spiral keels, the upper three forming a prominent slightly curved peripheral zone; a weak keel lies between the suture and the uppermost strong keel; two cords spiral into the wide umbilicus; aperture subcircular and oblique; peristome entire, outer lip thickened into a strong varix that on some specimens is slightly back from the lip edge; regularly spaced oblique axial threads most conspicuous in the wide flat depressions between keels. Well-preserved fossils from Recent beds retain the brownish-yellow color of the apex that is so char- acteristic of living specimens; remainder of shell white. Measurements of the figured specimen (E—l, Eniwetok, 710—720 ftl, USNM 648433: height 0.5 mm, diameter 0.7 mm. Occurrence: In describing this species as a Recent shell from Hawaii, Pilsbry noted that it was the smallest marine shell known to him from that area. It now has the added distinction of being the most widespread species—both geographically and geologically—in the 77 western Pacific island area.3 Recent shells have been collected from the Marshalls and from the Tuamotu Islands (Raroia) far to the southeast. Numerous fossils from Eniwetok and Bikini range downward to the lower Miocene (Tertiary e) at depth of 2,164 feet. In Fiji the species was found in abundance in the Suva Formation (sta. 160) on Viti Levu; age, Miocene (Tertiary f); single specimen from Tongatabu, Tonga (B. P. Bishop Mus, cat 202980, sta. 3), age probably Pleistocene. Lophocochlias appears to be closely related to Loddem'a Tate 1899, a genus represented by several species in the Recent fauna of the Australian region. Lophocochlias minutissimus exhibits variation in sculpture at each of the localities from which Recent or fossil shells have been obtained. Most of the numerous Fijian and Eni- wetok fossils and some of the Recent shells from Raroia show an additional secondary keel between the upper- most two primary keels. Lophocochlias paucicarinatus Ladd, n. sp. Plate 15, figures 6-8 Minute, turbinate; apex sharp, consisting of smooth whorls; body whorl descending at aperture, bearing three low primary keels, the upper one giving the shell a turreted appearance; obscure traces of secondary spirals are visible under high magnification, three on the base and one near the suture; umbilicus moderately wide, aperture subcircular, oblique; peristome entire, outer lip thickened into a strong varix that on one of the two available specimens lies a little back of the lip edge. Measurements of the holotype, USNM 648434: height 1.0 mm, diameter 1.2 mm. L. paucicarinatus has fewer primary keels and a nar- rower umbilicus than L. minutissimus and lacks the axial sculpture of that species. Occurrence: Two specimens from drill hole E—l on Eniwetok Atoll at a depth of 2,040—2,050 feet in beds assigned to lower Miocene (Tertiary e). Genus MUNDITIELLA Kuroda and Hebe Kuroda and Habe, 1954, Venus, v. 18, no. 2, p. 86, 90—91. Type (by original designation): Cyclostrema am- monoceras A. Adams. Recent, Japan. Munditiella qu-alum (Hedley) Plate 15, figures 9—11 Teinostoma qualum Hedley, 1899, Australian Mus. Mem. 3, pt. 7, p. 406, fig. 2. Small, depressed; spire nearly flat; width twice the height; suture impressed; aperture circular; peristome 8I have identified specimens from a well drilled on the coastal plain of Guadalcanal in the Solomon Islands (Baker, 1950). The shells were recovered from a depth of 380400 feet. Foraminifera from the same beds are thought to be Pleistocene but possibly Pliocene (Ruth, Todd, oral commun., 1964). 78 CHITONS AND GASTROPODS FROM W'ESTERN PACIFIC ISLANDS complete, thin inner lip extended below; umbilicus moderately wide, deep. Sculpture consisting of regularly spaced sharply elevated axial ribs (about 20 on body whorl) with fine, close—set spiral lines developed in inter- spaces; fine axial threads that override the spirals can be seen under high magnification; body whorl flattened and free of axial ribs immediately below suture and around the umbilicus. Measurements of the figured specimen from Eniwetok, USNM 648435: height 1.0 mm, diameter 2.0 mm. 1%. qualum is smaller than the type species 114. am- monoceras and has a more depressed spire. Occurrence: Single specimens from drill hole F—l, Eni— wetok Atoll, at depth of 280—290 feet, and Tongatabu, Tonga, at an altitude of 35 feet (B. P. Bishop Mus, cat. 202980); age of both occurrences probably Pleistocene. Abundant in beach drift on Rongerik Atoll. Hedley’s types were collected from the lagoon shore of Funafuti, Ellice Islands. Munditiella parryensis Ladd, n. sp. Plate 15, figures 12—14 Small, depressed; spire low, width more than twice the height; aperture circular, peristome complete; inner lip extended below; lower half of peristome thickened be- hind its edge by swellings at the ends of the spiral ridges; umbilicus wide and deep. Sculpture consisting of regularly spaced axial ribs (37 on body whorl) sepa- rated by wider interspaces bearing fine axial lines; spiral sculpture consisting of two obscure peripheral“ ridges, a third on the base, and a fourth that encircles the umbil- icus; all ridges best developed on the anterior part of body whorl. Measurements of the holotype, USNM 648436: height 1.1 mm, diameter 2.6 mm. M. parryensis has continuous axial ribs and a thick- ened peristome suggestive of M. archeri (Tryon, 1888, p. 89, pl. 33, figs. 84, 85, as Cyclostrema archer’i), Recent species from Singapore, but that species has spiral lirae between the axial ribs. Occurrence: Represented by three specimens from drill hole E—1 on Parry Island, Eniwetok Atoll, at depths of 35—40 (holotype), 750—760, and 850—860 feet; age of holotype, Recent; age of other two, late Miocene (Ter- tiary g). The two Miocene specimens are smaller than the holotype and appear to be immature. Genus TEINOSTOMA H. and A. Adams H. and A. Adams, 1853, Genera Recent Mollusca l, p. 122. Type (by virtual iiionotypy): Teinostoma politum A. Adams. Recent, Ecuador. Subgenus ESMERALDA Pilsbry and Olsson Pilsbry and Olsson, 1952, Aead. Nat. Sci., Philadelphia Proc. 104, p. 37, 39. Type (by original designation) : Teinostoma esmeralda Pilsbry and Olsson. Recent, Ecuador. T einostoma (Esmeralda) engebiense Ladd, n. sp. Plate 15, figures 15—17 Small; spire depressed; body whorl inflated, its periphery uniformly rounded; imperforate; last whorl descending near aperture which is subcircular and slightly contracted; peristome entire, upper part of lip extended forward; umbilical area covered by thin callus. Sculpture consisting of numerous fine spiral lines that are distinguishable on all save the earliest whorls but are more widely spaced near the umbilicus than else- where. Measurements of the holotype, USNM 648437: height 2.4 mm, diameter 3.8 mm. In size and shape, T. engebiense resembles T. rotatum, a Recent species described by Hedley from Funafuti, but that species is narrowly umbilicate, and on its base bears narrow radial bars of callus. Occurrence: A single fossil, the holotype, from shal- low drill hole, En—4, on Engebi Island, Eniwetok Atoll, at a depth of 1 foot; age, Recent. The species is living today in the Marshall Islands. Teinostoma (Esmeralda) marshallense Ladd, n. sp. Plate 15, figures 18—20 Minute, lenticular; spire depressed, base flattened; imperforate; aperture broadly ovate, oblique, slightly contracted; peristome entire; umbilical area covered by moderately thick pad of callus. Sculpture consisting of exceedingly fine spiral lines and, on the base, traces of radial lines visible under magnification. Measurements of the holotype, USNM 648438: height 1.1 mm, diameter 2.2 mm. T. marshallense is smaller and much less inflated than T. engebiense from Recent beds in the same area and has much finer spiral sculpture. Occurrence: Holotype from drill hole K—lB, Eniwetok Atoll, at depth of 863—873 feet; five additional specimens from beds immediately below (873—884 ft); age, early Miocene (Tertiary f). A single specimen from drill hole 2B on Bikini Atoll at depth of 2,175—2,185 feet is from beds still lower in the Miocene (Tertiary e). Teinostoma (Esmeralda) sp. A Plate 15, figures 21—23 Minute, discoidal; spire depressed, thick; imperforate; aperture subcircular, slightly contracted; outer lip ex- PALEONTOLOGY 79 tended forward. Sculpture consisting of c10sely spaced spiral lines. Measurements of the figured specimen, USNM 648439: height 0.7 mm, diameter 1.5 lnm. Teinostoma sp. A resembles T. marshallense but is smaller, has coarser sculpture, and is less heavily callused in the umbilical region. Occurrence .' Represented by two somewhat worn speci- mens from the conglomerate at the base of the limestone in the Suva Formation on Walu Bay, Suva, Fiji (sta. 160); age, early Miocene (Tertiary f). Genus SOLARIORBIS Conrad Conrad, 1865, Am. Jour. Conchology, v. 1, p. 30. Type (by subsequent designation, Dall, 1892, Wagner Free Inst. Sci. Trans, v. 3, pt. 2, p. 414: Delphinula (lepressa Lea, Eocene (Claiborne Group) of Alabama. Solariorbis tricarinata (Melvill and Standen) Plate 16, figures 1—3 Leucm'hynchia tricarinata Melvill and Standen, 1896, Jour. Conchology [Leeds], V. 8, p. 311, pl. 11, figs. 75a, b. Shell discoidal, thick; spire low; periphery with three prominent keels separated by deep grooves, the middle keel larger than others and with a median depression close to the aperture; ends of keels truncated near aper- ture and covered by callus; whorls of protoconch smooth, subsequent whorls, including most of the body whorl, marked by low oblique radiating folds that extend less than half way across the otherwise smooth surface of the whorls. On the base, the exposed three-quarters of the body whorl bears 13 strong folds that radiate from the umbilicus; on the remainder of the base, the folds are covered by callus which thickens into a projecting pad that shields the umbilicus when viewed from below; callus also covers the keels above the columella. Measurements of the figured specimen (drill hole E—l, 990—1,000 ft), USNM 648440: height 1.6 mm, diameter 2.8 mm. Occurrence: A rare shell from seven drill holes on Eniwetok and Bikini Atolls in the Marshall Islands. Total specimens, 13. The range is from Recent rocks close to the surface to Miocene (Tertiary e) at a depth of 1,471 feet. No Recent shells were found at Bikini and Eniwetok Atolls in spite of intensive collecting, but many examples were found in collections of drift shells from the nearby atolls of Rongerik and Rongelap. All the Recent shells are badly worn. This distinctive species is one of the few mollusks that can be traced in the drill holes from Recent to lower Miocene beds without detectable changes. The Recent shell was first described from the Loyalty Islands and was later reported by Hedley from the beach facing the Funafuti lagoon (Hedley 1899a, p. 406). Unusual features that distinguish it from other members of the genus are the strong peripheral ribs, the middle one being grooved near the aperture, and the thick pad of callus that shields the umbilicus. Solariorbis? sp. Plate 16, figures 4, 5 Small, thick; spire low, consisting of 31/2 rounded whorls, the last with a low keel at the periphery; aper- ture subcircular; inner lip callused and somewhat ex- tended below by an obscure ridge that issues from a nar- row umbilicus. Sculpture consisting of fine close-set spiral striae over the entire shell and regularly spaced axial wrinkles on the base. Measurements of the figured specimen, B. P. Bishop Museum, geology No. 1236: height 1.3 mm, diameter 1.9 mm. The single fossil does not appear to be closely related to any described species, but the shell is worn and not suitable for a type. The reference to Solariorbis is ques- tioned because the umbilicus is narrow, its ridge obscure, and there is no indication of a groove or channel at the junction of the upper edge of the outer lip with the parietal callus. Occurrence: In the conglomerate at the base of the limestone in the Suva Formation exposed on Walu Bay, Suva, Fiji (sta. 1601; age, early Miocene (Tertiary f). Genus LYDIPHNIS Melvill Melvill, 1906, Malacological Soc. London Proc., v. 7, p. 25. Type (by monotypy): Cyclostrema euchilopteron Melvill and Standen. Recent, Gulf of Oman. Lydiphnis eniwetokense Ladd, n. sp. Plate 16, figures 6—8 Small, wider than high, strongly turreted; apex flat; protoconch of 11/2 glossy convex whorls followed by 21/2 dull flattened sculptured whorls; body whorl with two strong spiral keels with scalloped margins; the margin of the higher keel turned upward. Aperture subquadrate, broadly extended below the columella; umbilicus wide. Secondary sculpture consisting of a spiral rib between the two keels, a second spiral rib below the lower keel and a conspicuously beaded rib that spirals into the umbilicus; an obscure nodose rib developed on the body whorl immediately below the suture. Close-set tertiary spirals on the flattened upper surface of the body whorl. Axial growth lines are especially prominent in the area between the two keels. Both the holotype and paratype 80 CHITONS AND GASTROPODS retain traces of broad axial bands of brown on the upper part of the body whorl. Measurements of the holotype (drill hole K—lB, 936— 946 ft), USNM 648441: height 1.8 mm, diameter 2.1 mm. Paratype (E—l, 590—600 ft): height 1.1 mm, diameter 1.6 mm. Two other specimens from hole E—1 are smaller and appear to be immature. The type species of Lydiphnis, L. euchilopteron (Mel- vill and Standen), is a larger ReCent species in which the third or middle keel is much more prominent than on the Eniwetok fossils; the fossils likewise have a higher spire. Occurrence: Four specimens from two drill holes on Eniwetok Atoll at depth of 590—946 feet; age, Pliocene to early Miocene (Tertiary h—fl. Genus CYCLOSTREMISCUS Pilsbry and Olsson Pilsbry and Olsson, 1945, Acad. Nat. Sci. Philadelphia Proc., V. 97, p. 266. Type (by original designation): Vitrinella panamcnsis C. B. Adams. Recent, Pacific coast of Panama. Cyclostremiscus emeryi Ladd, n. sp. Plate 16, figures 9—11 Minute; spire fiat, apex sunken, diameter approxi— mately twice the height; protoconch of single smooth whorl followed by two sculptured whorls; umbilicus wide and deep; aperture subcircular, peristome continuous, outer lip thin, slightly angled by carinae. Sculpture con- sisting of about nine spiral carinae, two at the periphery being larger than the others; all carinae except the peripheral pair are conspicuously beaded. Measurements of the holotype (E41, Eniwetok, 780— 790 ft), USNM 648444: height 0.4 mm, diameter 0.9 mm. Paratype (E—l, Eniwetok, 990—1,000 ft) ; height 0.5 mm, diameter 1.0 mm. The species is characterized particularly by its two strong almost smooth peripheral carinae with con- spicuously beaded carinae above and below. Occurrence: Eight specimens from drill hole E41, Eni- wetok Atoll, at depth of 630—1589 feet; age, Miocene (Tertiary e—g‘). Two Recent specimens were recovered from beach drift on Rongerik Atoll and one was dredged from Bikini lagoon at a depth of 15 fathoms. Subgenus PONOCYCLUS Pilsbry Pilsbry, 1953, Acad. Nat. Sci. Philadelphia Mon. 8, p. 426. Type (by orginal designation; : Adeorbis beaui Fischer. Recent, southeastern United States and West Indies. FROM WESTERN PACIFIC ISLANDS Cyclostremiscus (Ponocyclus) novemcarinatus (Melvill) Plate 16, figures 12—14 chloslrmna novem—carirmtum Melvill, 1907. Malacologieal Soc. London Prom, v. 7, p. 22. pl. 3, figs. 3, 3a. l'ilrinclla (Lydiphnix) novemcariuatum. Melvill. Beets. 1941, Geol.—mijnb. genootsch. Nederland en Kolonien Verh., Geol. ser., v. 13, pt. 1, p. 25, pl. 1, fig. 59, pl. 9, figs. 343—345. Small; spire depressed; widely umbilicate, aperture oblique, subcircular. Sculpture consisting iof strong spiral carinae, 8—10 on last whorl, the third and fourth from the top being larger than the others; radial striae visible under high power. Measurements of the figured specimen (K«1B, 873—884 ft), USNM 648442: height 1.0 mm, diameter 2.0 mm. The Eniwetok fossils are identical with Recent shells from the Cook Islands. The radial striae of the fossils appear to be less conspicuous than those originally de- scribed by Melvill on Recent shells from the Gulf of Oman, but I have not seen specimens from the type locality. Occurrence: Four fossils from two drill holes on Eni- wetok Atoll at a depth of 873~970 feet; age, early Miocene (Tertiary fl. A single large worn shell collected from beach drift on Rongerik Atoll. Described by Beets from the upper Miocene of East Borneo. Cyclostremiscus (Ponocyclus) cingulifera (A. Adams) Plate 16, figures 15—17 Cyclostrema cingulifera A. Adams, 1850, Zool. Soc. London Proc., p. 43. Sowerby, 1863, Thésaurus Conchyliorum, pt. 23, p. 250, p]. 255, figs. 13—14. Tryon, 1888, Manual Conchology, v. 10, p. 93, pl. 32, figs. 72, 73. Vitrinella cingulifera (A. Adams), Altena, 1938, Leidsche Geol. Mededel., v. 10, p. 298, fig. 17a—c. (See for additional citations.) Medium size; spire low; widely umbilicate; aperture oblique, nearly circular with slight angle above; inner lip thinly callused. Sculpture consisting of strong uni- formly spaced spiral carinae; 9—11 carinae of body whorl are subequal in size except for highest and lowest which are smaller; peristome thin, axial lines of growth appear on the early whorls and in the umbilicus but cannot be seen elsewhere except under high magnification. Measurements of the figured specimen (Palau, USGS 21304), USNM 648443: height 2.4 mm, diameter 4.0 mm. Occurrence: Eight specimens from the marls at the base of the Palau Limestone in the Goikul area (USGS 21301, 213041, Babelthuap, Palau; age, late Miocene (Tertiary g). LOCALITIES Recent shells have been reported from the Philippines, Japan, and other parts of the Indo-Pacific; fossil occur- rence include the Pliocene and older beds of Java. Genus COCHLIOLEPIS Stimpson Stimpson, 1858, Boston Soc. Nat. History Proc., v. 6, p. 304. Type (by monotypyl: ('ochliolepis parasittca Stimp- son. Recent, South Carolina. Cochliolepis diangal-ana Ladd, n. sp. Plate 16, figures 18—20 Small, diseoidal; width more than twice the height; about three whorls, the last rapidly expanding, flattened near suture, partly embracing the preceding whorl; suture impressed; aperture oblique, subquadrate; um- bilicus moderately wide, deep. Sculpture consisting of close-set spiral lines and coarser, more widely spaced wrinkles of growth. Measurements of the holotype, USNM 648445: height 0.8 mm, diameter 2.0 mm. The Palauan fossil appears to be more strongly sculp- tured, both spirally and axially, than other fossil and Recent species. Occurrence: Fifteen specimens from late Miocene lTertiary g) marls at the base of the Palau Limestone in the Goikul area, Babelthuap Island, Palau (USGS 21301 lholotypel and 21304). Genus VITRINELLA C. B. Adams Adams, C. B., 1850, Monograph Vitflnella, p. 3. Type (by subsequent designation Bush, 1897, Con- necticut Arts and Sci. Trans, v. 10, p. 105, 122): Vitrt'nella helicoidea C. B. Adams. Recent, Jamaica. Vitrinella 3);). A Plate 16, figures 21—23 Small, discoidal, depressed; aperture subcircular, oblique; inner lip thickened by slight expansions above and below; umbilicus narrow and deep, bordered by a beaded rib. Sculpture consisting of very fine spiral striae that are a little coarser near the umbilicus than else- where. Measurements of the figured specimen, USNM 648446: diameter 1.5 mm, height 0.9 mm. The small and possibly immature shells are tentatively assigned to Vitrinella because of the open umbilicus and spiral rib. They are, however, heavier and have stronger spiral sculpture than most Vitrinellas. Occurrence: Single shell from drill hole 213 on Bikini Atoll at depth of 1,723—1,734 feet; age, early Miocene (Tertiary e); two Recent shells were collected from drift near Bikini Island. 81 LOCALITIES Data on localities from which specimens studied were collected are given in the tables and illustrations that follow Palau [Babelthuap localities shown in fig. 2] Island USGS Locality and collector Cenozoic Auluptagel. _ _ 17715 Acropnra zone at base of Palau Limestone at contact with underlying volcanic (Ngarsul Member of Aimeliik Formation) at southeast part of volcanic area, on west end of northern peninsula. P. E. Cloud and Arnold Mason 1948. Do _______ 18322 Road to lighthouse, altitude 350 ft. Arnold Mason and P. E. Cloud, 19 Do ______ 21290 4rropora zone at base of Palau limestone directly above contact with underlying volcanic (Ngarsul Member of Aimeliik Formation) immediately south- east of causeway to Malakal: altitude 0— 6 ft. H. S Ladd, 1958. Do ....... 23642 Upper foot of breccia in quarry at south end of bridge ’ Malakal. G. Corwin and J.I. Tracey, Jr., 1964 Babelthuap. . _ 21301 Marl facies at base of Palau Limestone, Goikul penin- sula (exact 10c. on fig. 2), 11.8. Ladd, 1958. Do ______ 21304 Same as 21301 (fig. 2). Do ______ 21308 Do. Do ,,,,,, 21310 Do. Western dock 1000 FEET FIGURE 2.—Sketch map of Goikul peninsula showing fossil localities and attitude of mail beds, southeasteln Babelthuap, Palau. iWariano Islands [Guam fossil localities shown in fig. 3; Saipan and Tinian localities in fig. 4] Island L'SGS Locality; collector, Pacific Island Engineers, 1946750, Cenozoic unless otherwise indicated Guamunum 17416 West half of quarry at northeast corner of Harmon I‘ield. RE. Cloud, .lr., 1 . Dc ______ 17446 About 2% miles east—southeast of Wettengel Junction, PE. Cloud, .lr. and ILG. Schmidt, 1949. Do ______ 17776 In bed of Talefac River south of Agat. about 150 ft from coast, close to high-tide level. PE. Cloud, Jr. and R.G. Schmidt, 1948. 20489 200 ft west of Fadian Point, east coast of island. 20499 1,4010 {5 northeast of Tantapalo Point, west coast of is an . 2051] 3,700 ft southeast of Ordot, waist of island. 20517 3,400 ft north of Fadian Point, east coast of island. 20526 3,050 ft south of Sinajana, waist of island. 2053] About 2% miles east of Tamuning, waist of island. 20533 4,000 ft southeast of Sinajana, waist of island. 20534 About 600 ft south of Taguag, west coast of island. 20536 1% miles east-southeast of Ordot, waist of island. 20555 About 3,000 ft southeast of Toto, waist of island. 20560 About 5,000 ft southeast of Toto, waist of island. 20574 4,600 ft east-northeast of Sinajana, waist of island. 20579 4,000 ft east-southeast of Sinajana, waist of island. 20585 5,600 ft northwest of Fadian Point, waist of island. 20590 About 3.000 ft east-northeast of Toto, waist of island. 20600 About 4,700 ft southeast of Ordot, waist of island. 82 CHITONS AND GASTROPODS FROM WESTERN PACIFIC ISLANDS Ritidian Point fpafalofl XXJ\§§§ Pati Point 3 Haputo Point @443 .Uhtbengel J ct /g; H (\ Catalina Point armon p;>\_fv Sa u pon Point 3. ¢\ <7 Mount Aguna Bay % x Barrigada Hill Asan Point W{ C CABRAS | /.-4‘ )3) k4 ' Taguag '7’ U Taguan Point Ap'ra Harbor 7 64 ambulata __________________________ 64 beetsi _____________________ 13, 18, 64; pl. 12 parasitica, Cochliolepis _________________ 81 I’m ' " 59 parryensis, Cingula _____________________ 61 Cingula (Peringiella) _______ 13, 18, 61 ; pl. 11 Munditiella _______________ 14, 18, 78; pl. 15 Rissoina (Rissoina) ambigua 14, 18, 72; pl. 14 l’arvisetia _____________________________ 60 I’atella ______ _ 32 apertura - __ 31 barbara _- - 32 fissura _____________________________ 27 groeca _____________________________ 31 octoradiata ___________________ __ 29 plitata _______________________ _ 32 stellaeformis _ 32 Iricostata _ _______________ 29 vulqata ____________________________ 32 (Srulellastra) stellaeformis __ 12, 16, 32; pl. 3 Patellidae ___________________________ 12, 16, 32 patula, Fossarirza _______________________ 36 paucicarinatus, Lophocochlias __ 14, 18, 77; pl. 15 peasei, Emarginula _____________________ 28 petholatus thanus, Turbo (Turbo) __-____ 13, 17, 47; pl. 7 Turbo _____________________________ 47 (Turbo) _____-____-__ 13, 17, 20, 47; pl. 7 petrosum, Astralium (Cyclocantha) _______ 43 Page petrusum viroscens, Astralium _-__________ 43 phuraom'us, Troohus ____________________ 38 PE ‘ "n 53 .— .;. 54 III ‘ 54 uariabilis ___________________________ 54 sp. _______________________ 13,17, 53; pl. 10 Phasianellidae _______________________ 13, 17, 53 Phosinella _____________________________ 68 phymotis, Stomatiu __________-_ 12, 17, 41; pl. 5 Emarginula (Emarginula) ___ 12,16,28; pl. 2 Pecten __________ 4, 8 peloronta, Nerita 55 Peringiella _____________________________ 61 perlatus, Turbo (Marmaroatoma) _____ 13, 17,49 (Senectus) 49 I’errinia _______________________________ 36 petholatus, Turbo (Turbo) -_ l3, 17, 20, 47; pl. 7 petrosum, Astralium (Cyclocantha) _______ 43 petrusum virescens, Astralium ___________ 43 phamonius, Trochus ____________________ 38 picta, Collonia _________________________ 53 Leptothym __________ 13, 17, 53; pl. 9 Lucilina ____________ _ 24 pictus, Trochua .. _ 35 I’isirma ____________________________ 62 , Alvania 63 Merelina (Merelina) ___- 13, 18, 20, 63; pl. 12 I’isulina _______________________________ 19, 59 adamsiana ________________ 59 subpacifica _-__-_- __ 13, 17,59; pl. 11 pisum, Gibbula _ __________ 36 Plesiotrochua ___________________________ 59 plicafa, Neritu _________________________ 56 Patella _____________________________ 32 Rissoina ___________________________ 74 (Rissolina) _ 14, 18, 20, 74 , pl 14 plicatula, Rissoina _ _____________ 72 /polita, Nerita ______________________ 56 Nerita (Amphinerita) ______ 13, 17, 56; pl. 10 politum, Teinostoma ____________________ 78 polyps, Schizochiton ___- - 22 Ponocyclus ___________________________ 80 P ~' ‘in 60 Pseudostomatella _______________________ 41 (Pseudostomatella) maculata _________ 12, 17, 20, 41; pl. 5 P1,, A 4 3,14 sp. A ___-_______-___-_-__-____-__-_ 3 pulchra, Rissoa _ 68 pulligera, Nerittz 57 N erilina ___________________________ 57 pullus, Turbo __________________________ 54 punctulum, Rissoa _______ _ 62 Putilla _________________ _ 60 lucida _ _ 60 scillae __-_ __________________ 61 semiatriata _________________________ 60 .1 ' 61 (Parvisetia) goikulensis __ 13, 18, 60, 61; pl. 11 suvaensis ______________ 13, 18, 61; pl. 11 (Pseudosetia) morona __ _ 13,18, 60; pl. 11 Pyramidella ambigua ________________ 71 pyramis, Tectus (Tectus) ____________ 12, 16, 39 Trochus ____________________________ 39 Q quadricarinatus, Euchelus -_ _______ 34 Euchelux (Euchelus) - 12, 16, 88; pl. 3 Trochus ____________________________ 33 qualum, Munditiella ___________ 14, 18, 77; pl. 15 Teirzostoma _________________________ 77 R radiatus, Turbo ________________________ 49 radula, Nerita _________________________ 55 Nefitopsis __________________________ 55 Page (Neritopsis) ________ 13, 17, 20, 55; pl. 10 rangiuna, Smaragdia ____________________ 59 Smaragdia (Smaragdia) ____ 13,17,58; pl. 11 raumma, Gabrielonu ______ _ 13, 17, 54; pl. 10 rehderi, Tectarius ____________ __ 21 chtarius (Subditotectarius) __________ 13, 17, 59; pl. 11 rhodostoma, Astraea ____________________ 43 Astraea (Astralium) _________ 13, 17, 43; pl. 6 rhodostomus, Trachus ___________________ 43 rilebana, Rissaina (Schwartziellu) 14, 18, 67; pl. 12 Rimula. ______________ __ 30 blainvilli __ ____________ 30 erquisita ________________ 12, 16, 20, 30; pl. 2 sp. ________________________ 12,16,30; pl. 2 Rissoa ambigua ________________________ 71 cheilostoma ________________________ 63 glabrata ___- _ 62 gracilia ___ _ 66 gradata ___ __ 63, 64 invisibilis __________________________ 64 laevis ______________________________ 6] mandralisci 62 monluqm' _ 62 pulchru _____ 68 punctulum 62 rubra ______________________________ 75 subulum ___________________________ 62 sardea _____________________________ 62 scillae ___- 60 swninulum __ 62 sub/usca _- 62 turgida ____________________________ 60 Rissoidae . ______________ l3, 14, 18, 6’0 Rissoina ________________________ 60, 66, 70, 72 ailinana ____________________________ 8, 71 ambigua 71 balteata 69 browniana 64 bryerea ____________________________ 66 cerithiformia ________________________ 69 clathrata ___- __________________ 68, 69 concinna __ __________________ 72 coronata, __ _ 64 l'nstulufa ___________________________ 69 decussata __________________________ 67 ephamilla __________________________ 73 gigantea ___________________________ 65 gracilis ___ _ 66 inca _ _ 70 indrai _____ __ 20, 67 kickarayana ________________________ 74 marshallensis _______________________ 73, 74 materinsulue _______________________ 71 multozona __________________________ 69 plicata ___- 74 pliratula _________________ 72 scalariformis 73 semari _____________________________ 73 supracosmta _______________________ 68 tenuistrz'ala __ _ 68 transenna _ _____ 69 triticea ___- _ 67 turrz'cula ___________________________ 20, 72 (Phosinella) alerisi ________ 14, 18, 70; pl. 13 bulteata ____________ 14, 18, 20, 69; pl. 13 bikiniensis _____________ 14, 18, 6'9; pl. 13 briggsi -___ ______ 14, 18, 68; pl. 13 rlathrata __ _ 14, 18, 20, 68; pls. 12, 13 transenna ___ _____ 14, 18, 20, 69; pl. 13 (Rissoina) ahboth‘ _________ 14, 18, 70; pl. 13 ailinana _______________ 14, 18, 70; pl. 13 ambigua ______ __ 14, 18, 71; pl. 14 parryensis _ _ 14, 18, 72; pl. 14 ('uncinna ______ _ 14, 18, 72; pl. 13 ekkanana ______________ 14, 18, 71; pl. 13 goikulensis _____________ 14, 18, 71 ; pl. 13 lomaloana _____________ 14, 18, 71; pl. 13 INDEX Page mijuna ________________ 14, 18, 70; pl. 13 waluensis ______________ 14, 18, 71; pl. 13 sp. A _________________ 14, 18, 72; pl. 13 (Rissolina) bourneae _______ 14, 18, 74; pl. 14 ephamilla ___________ 14, 18, 20, 78; pl. 14 harti _____ ___ 14, 18, 74; pl. 14 herringi _ _ 14, 18, 74; pl. 14 kickarayana ___ ___- 14, 18, 74; pl. 14 marshallensis _______ 14, 18, 73; pls. 13, 14 plicata _____________ 14, 18, 20, 74; pl. 14 turriwla ____________ 14, 18, 20, 72; pl. 13 sp. B _________________ 14,18,76; pl. 14 (Schwartziella) flexuoxa ___- 14, 18, 66; pl. 12 gracilis ________________ 14, 18, 66; pl. 12 mdrm __- ___ 14, 18,66; pl. 12 jirikana _______________ 14, 18, 67; pl. 12 mejilana _______________ 14, 18, 67; pl. 12 rilebana _______________ 14, 18, 67; pl. 12 (Zebinella) emuanana ______ 14, 18, 67; pl. 12 supracostata ___ 14, 18, 68; pl. 12 tenuistriata _________ 14, 18, 20, 68; pl. 12 Rissulina ______________________________ 72, 74 Ritena ________________________________ 56 Rm‘hia ________________________________ 39 rosacea, Gena ___--- __________ 42 Synaptocanhlea ___ _ 12, 17, 20, 42; pl. 5 ruseocincta, Cingulu _________________ 61 Cingula (Peringiella) _______ 13, 18, 6'1 ; pl. 11 rutatum, Teinostoma ___________________ 78 rubicundus, I’adollus ___________________ 25 rubida, Neritilia _______________________ 58 Neritina ___- _ 57 rubra, Barleeia __ _ 75 Rissoa _______________ 75 russelli, Lucilina _______________ 12, 16, 23; pl. 1 S sabulum, R1380" ________________________ 62 sagittata, Cellana - 12, 16, 32 Helcioniscus __ _ 32 sarcina, Denturene - 46 sardea, Rissoa _________________________ 62 scabu' ' , E ” ’4 33 scalari/ormis, Rissaina __________________ 73 Schizochiton _________________________ 1, 19, 21 incisus __________ 21, 22 goikulensis __________ 12, 16, 21, 22; pl. 1 marshallensis __ ________ 12, 16, 22; pl. 1 polyps _____________________________ 22 Schizochitonidae ____________________ 12, 16, 21 Schwartziella __________ ___ 66, 67 xcillac, Putilla _____-- _ 61 Rissoa ___- _ 60 Scissurella _____________________________ 26 aedom'a ____________________________ 27 roronata ___________________________ 27 ('rispata ____________________________ 27 derlinanu __ _ 26 equatoria __ _ 27 \laevigatu __________ _______ 26 (Auatoma) equatoria ________ 12, 16, 27; pl. 2 (Scissurella) coronata _______ 12, 16, 27; pl. 2 (leclinans ____________ 12, 16, 20, 26; pl. 2 Scissurellidae ________________________ 12, 16, 26 Scurellaslra _ _ 32 Srutus ______________ 30, 31 untipodes _________________ 30 (Nannosmtum) sp. A _______ 12, 16, 31; pl. 2 sp. B __________________ 12,16,81; pl. 2 somari, Rissoina ________________________ 73 Smamgdia ____________ , _____________ 59 seminulmn, Rissoa ____________ 62 semirugosa, .Veritu (Theliostyla) _________ 56 semistriata, Putilla _____________________ 60 setosus, Turbo _________________________ 48, 49 Turbo (Marmarostoma) _-___ 13, 17,49; pl. 7 Sinum lekalekanum _____________________ 42 97 Page Smaragdia _____________________________ 20, 58 rangiana ___________________________ 59 semari _____________________________ 59 (Smaragdia) colei _________ 13, 17, 68; pl. 11 jogjacartensia ______ 13, 17, 58; pls. 10, ll rangiana ___- _-___ 13,17,68; pl. 11 sp. A ___- ___ 13,17, .59; pl. 11 Solariorbis _________________ 79 tricarinata _____________ 14, 18, 20, 79; pl. 16 sp. _______________________ 14, 18, 79; pl. 16 souberbiana, Emarginula ________________ 28 souverbiana, Emarginula ________________ 28 Emarginula (Subzeidom) _ 12, 16, 28; pl. 2 slellae/ormis, Patella _______ ____-____ 32 Patellu (Scutellastra) _ _ 12, 16, 32; pl. 3 stellata, Euchelus _______________________ 36 stephensoni, Leucorhynchia -_ 14, 18, 76, 77; pl. 14 Stomatella _____________________________ 41 H ‘II 34 b ' 41 maculata ___________________________ 41 montrouzieri 41 papyracea __________________________ 41 (Synaptocochlea) conci’rma ___________ 42 Stomatellidae _______________________ 12, 17, 41 Sfomatia ______________________________ phymotis striatus, Cryptoplar ____________________ 25 subcarinatus, Trochus __________________ 37 Subditotectarius ________________________ 21, 59 sub/used, Rissoa _______________________ 62 sublathrata, Emarginula _ _______ 29 subpacifica, Pisulina ___ _ 13,17,69; pl. 11 Subzeidora _____________________ 28 supracostata, Rissoina __________________ 68 Rissoina (Zebinella) _______ 14, 18, 68; pl. 12 suvaensis Euchelus (Herpetopoma) instrictus 12, 16, 33; pl. 3 l’utilla (Parvisetia) ___---“ 13, 18, 61; pl. 11 Synaptocochlea _ _________ 41 concinna ___- - 12, 17, 41; pl. 5 lekulekana _________________ 12, 17, 42; pl. 5 marshallensis _______________ 12, 17, 42; pl. 5 rosacea _________________ 12, 17, 20, 42; pl. 5 'I‘ Taramellia _____________________________ 69 Teotarius _______________________________ 21, 59 coronatus __________________________ 59 rehderi _____________________________ 21 (Subditotectarius) reh deri _ Tectus _______________________________ b fenestratus _________________________ ohelisrus ___________________________ pagodalis __________________________ (Rochia) m'lotirus __________ 12, 16, 39; pl. 4 (Tectus) bomasensis _ __ 12, 16, 39; pl. 4 mauritianus ___- _____ 12, 16, 38; pl. 4 pyramis __ ___________ 12, 16, 39 Tciuostoma ____________________________ 78 cngebiense __________________________ 78 esmeralda _ __ 78 politum _ __ 78 qualum _ -_ 77 rotatum ____________________________ 78 (Esmeralda) engebiense _-__ 14, 18, 78; pl. 15 marshallense ___________ 14, 18, 78; pl. 15 sp. A _________________ 14, 18, 78; pl. 15 (Leucorhynchia) caledonicum ___---___ 76 crossei ___--___..________ __ 76 lelkibana, Merelina (Lineme'ra) _ 13,18, 64; 131.12 tenuistriuta, Rissoina ___________________ 68 Rissoina (Zebinella) __-_ 14, 18, 20, 68; pl. 12 Thalotia _______________________________ 20, 35 berauensis 19 elangatus ___________________________ 35 98 Page erinat‘eux ___________________________ 20, 35 (Bemua) sp _______________ 12, 16, 35; pl. 3 (Thalotia) berauensis _______ 12, 16, 35; pl. 3 elongatus _______________ 12, 16, 815; pl. 3 thanus, Turbo (Turbo) petholatus 13, 17, 47; pl. 7 Thatcheria _____________________________ 5 vitiensis ____________________________ 5 ’l'heliostyla ____________________________ 56' Tlmodorus corona ______________________ 57 (Clithon) corona ____________________ 57 truceyi, Neritilia _____ 13, 17, 57; pl. 10 transemza, Rissoina _-- _____________ 69 (Phosinella) ________ 14, 18, 20, 6'9; pl. 13 tricarinata, Leucorhynchia _______________ 79 Solariorbis _____________ 14, 18, 20, 7.9; pl. 16 Tricoliu ___-_____-____..___________' _____ 54 variabilis ___________________________ 55 (Hiloa) variabilis 13, 17, .54; pl. 10 sp. A _____ _ 13,17,65; pl. 10 lricostata, Patella _ ________ 29 Tridacna ______________________________ 4 rridentata, Zebina ______________________ 65 triticea, Rissoina _______________________ 67 Trochidne __________________________ 2, 16, 33 (rochlearis, Iravadia __ 60 Trochus _____ _ 37 at'utangulus _ 39 belcheri ____________________________ 41 calcaratus __________________________ 37 ralliferus ___________________________ 40 (onus ______________________________ 39 Izeliotropium _ 43 histrio _____________________________ 37 histrio _ 37 imperialis ___________________________ 43 incrassatus _________________________ 38 creniferus _______________________ 38 maculatus __________________________ 37 magus _____________________________ 36 mauritianus ________________________ 38 nilotirus ___________________________ 39 obeliscus ___________________________ 39 phamonius _________________________ 38 pictus _____________________________ 35 pyramis ___________________________ 39 quadriwrinalus _____________________ 33 rhodastomus ________________________ 43 INDEX Page subcm‘inutus ________________________ 37 tum/ems ___________________________ 38 (Infundibulum) calcaratus ___________ 43 maculatus _____________ __ 37 (Alonilea) lifutmus __ ___ 40 (Monodonta) instrictus - __ 33 (Rochia) niloticus __________________ 39 (Teclus) obelixcus ___________________ 39 (Troohus) hiatrio ____-___ 12, 16, 20, 37; pl. 4 incmssatus ___________________ 12, 16; 38 marulatus _ 12, 16, 20, 37; pl. 4 tubiferus _______________ 12,16, 38; pl. 4 tuhi/erus, Trochus ______________________ 38 Trachus (Trochus) __________ 12, 16, 38; pl. 4 Turbinidae _________________________ 13, 17, 43 Turbo ___---____- __ 43, 1,7, 66 argyrostamus - -- 27, 48, 49 ralcar ________ -_ 43 canaliculatus _______________________ 49 chrysostomus _______________________ 48, 49 cingillus ____________________________ 61 crassus _____________________________ 49 delphinus _ 42 histrio ___- 37 petholatus 47 pullus _____________________________ 54 radiatus ___________________________ 49 sctosus _____________________________ 48, 49 zetlandica __________________________ 63 (Marmarostoma) argyrostomus _____-_ 13, 17, 20, 48; pl. 7 chrysostomus ________ 13, 17, 20, 48; pl. 7 crassus _________________ 13, 17, 49; pl. 8 perlatus _____________________ 13, 17, 4.9 setosus _________________ 13, 17,49; p]. 7 sp. A __________________ 13, 17, 49; pl. 8 (Ocana) gruneri ___- 49 (Senectus) perlatus ____"_ _____________ 49 (Turbo) chrysnstomus _______________ 48 petholatus ___________ 13, 17, 20, 47; pl. 7 thanus 7 ______________ 13, 17, 47; pl. 7 49 49 3.5 monilifera _________________________ 35 (Perrinia) morrisoni ___ 12, 16, 20, 36; pls. 3, 4 Iurgida, Rissoa ________________________ 60 Page turricula, Rissuina ______________________ 20, 72 Rissoim (Rissolina) _____ 14, 18, 20, 72; pl. 13 Iuvuthaensis, Haliotis ________________ 12, 16, 26 U ulauensis, .V'eritina ___- - 57 umlaasiana, Nerita - _ 55 undata, Nerita _________________________ 56 Nerita (Ritena) _________________ 13, 17, 56‘ V Vuceuuhelus ___________________________ 34 variabilis, Collonia _____________________ 54 PL. ' 1]” 54 Tricolia ____________________________ 55 (Hiloa) _____________ _ 13, 17, 54; pl. 10 virescens, Astralium petrusum _ ___- _-__ 43 virginea, Nen'ta ____________ 57 viridis, Nerita __________________________ 58 Vitiastraea ____________________________ 21, 45 vitiensis, Nodularia ____________________ 4 Thatcheria _________________________ 5 Vitrinella _-____ 81 cinguli/era .. 80 helicoidea __________________________ 81 , msis __ 80 (Lydiphnis) novemcarinatum _________ 80 Sp. A _____________________ 14, 19, 81; pl .16 Vitrinellidae _____________ 75 Vitta __________ IE7 vulgata, Patella ________________________ 32 W wuluensis, Astrwea (Astralium) __ 13,17, 43; pl. 6 Rissoina (Rissaina) ________ 14, 18, 71; pl. 13 wellsi, Leptothyra ______________ 13, 17, 52; pl. 9 Z Zebina _____________________________ 21, 64, 66’ abrardi ____________________________ 21 tridentala __________________________ 65 (Ailinzebina) abrardi ..___ 14, 18, 20, 65; pl. 12 (Cibdezebina) metaltilana 14, 18, 20, 64; pl. 12 (Morehiella) cooperi _______ 14, 18, 66; pl. 12 killeblebana ____________ 14, 18, 65; pl. 12 sp. A _____________________ 14,18, 66; pl. 12 Zebinella ______________________________ 67 zet.’ "’ , Turbo 63 fiU. S. GOVERNMENT PRINTING OFFICE: 1966 O — 212-807 FIGURES 1—3. 4—9. 10—12. 13—15. 16. 17. 18, 19. 20, 21. 22. 23—27. 26, 27. 28—30. 29, 30. PLATE 1 Schizochiton incisus goikulensis Ladd. n. subsp. (p. 21). Holotype, a tail valve, length 10.0 mm, X 5. Palau; late Miocene (Tertiary g). USNM 648208. Schizochiton marshallensis Latld, n. sp. (1). 22). 4—6. Holotype, a tail valve, length 8.2 mm, X 5. . E—l, Eniwetok, 870—880 ft; early Miocene (Tertiary f) USNM 648209. 7. Paratype A, a head valve, length 5.5 mm, X 5. F—l, Eniwetok, 740—750 ft; late Miocene (Tertiary g). USNM 648210. 8. Paratype B, a second valve, length 7.2 mm, X 5. F—l, Eniwetok, 750—760 ft; late Miocene (Tertiary g). USNM 648211. 9. Paratype C, a second valve, length (incomplete) 3.4 mm, X 8. 2A, Bikini, 1,030—1,034 ft; early Miocene (Tertiary f). USNM 648212. Laricdla sp. A (p. 22). 10, 11. A head valve, length 1.6 mm. X 8. F—l, Eniwetok, 55—60 ft; Recent. USNM 648215. 12. An intermediate valve, length (minus insertion plates) 2.0 mm, X 8. E—l, Eniwetok, 35—40 ft; Recent. USNM 648216. Lucilina russellz' Ladd, n. Sp. (p. 23). Holotype, a tail valve, length 4.1 mm, X 8. K—lB, Eniwetok, 537—548 ft; probably Pliocene (Tertiary h). USNM 648217. Lucilina sp. A (p.23). A tail valve, length (insertion plates missing) 2.1 mm, X 8. Palau; late Miocene (Tertiary g). USNM 648219. Lucilina sp. B (p. 23). A tail valve, length 6.5 mm, X 4. Fiji; probably Pliocene (Tertiary h). USNM 648218. Lucilina sp. (p. 24). An intermediate valve, length 0.9 mm, X 15. Funafuti, 70 ft; Recent. MCZ 28020. Acanthochitona sp. (1). 24). An intermediate valve, length 1.1 mm, X 15. E—l, Eniwetok, 770—780 ft; late Miocene (Tertiary g). USNM 648220. Cryptoplax cf. C. menkrawitensis Beets (p. 24). An intermediate valve, length (incomplete) 1.7 mm, X 15. Fiji (sta. 160); Miocene. USNM 648221. Cryptoplax sp. A (p. 24). 23, 24. Head valve, length 1.4 mm, X 20. E—l, Eniwetok, 750—760 ft; early Miocene (Tertiary f). USNM 648222. 25. Intermediate valve, length 2.1 mm, X 15. 2B, Bikini, 1,891—l,902 ft; early Miocene (Tertiary e). USNM 648223. Tail valve, length 1.1 mm, X 20. 2B, Bikini, 1,870—1881 ft); early Miocene (Tertiary e). USNM 648224. Cryploplax sp. B (p. 25). 28. Intermediate valve, length 7.3 mm, X 5. F—l, Eniwetok, 800—810 ft; late Miocene (Tertiary g). USNM 648225. Tail valve, length 5.5 mm, X 5. F—l, Eniwetok, 720—730 ft; late Miocene (Tertiary g). USNM 648226. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 1 CHITONS FIGURES 1, 2. 3—5 . 11, 12. 13,14. 15,16. 17,18. 19, 20. 21,22. 23. 24, 25. 26, 27. 28, 29. 30, 31. 32, 33. 34, 35. 36, 37. PLATE 2 Haliatis (Parlollux) (wind Gmelin (p. 25). Guam specimen, length 58.2 mm, X 1. USGS 20489, Reef facies, Mariana Limestone; Pliocene and Pleisto- cene. USNM 648227. Haliotis (I’m/011m) of. H. clathmtu Reeve (p. 26). 3,4. Guam specimen, length 24.8 mm, X 1. USGS 20994, detrital facies, Mariana Limestone; Pliocene and Pleistocene. USNM 648228. 5. Tinian specimen, length 15.9 mm, X 2. USGS 21611, limestone terrace probably equivalent to Mariana Limestone of Guam; Pliocene and Pleistocene. USNM 648229. Scisslm'lla (Scismu‘clla) (leclinans Watson (p. 26). Height 0.7 mm, X 20. Drill hole 2B, Bikini Atoll, depth 884—894 ft; late Miocene (Tertiary g). USNM 648230. Sets-surr’llu (Scissurclla) cm‘onala Watson (p.27). Height 1.3 mm, X 15. Drill hole E—l, Eniwetok Atoll. depth 30—35 ft; Recent. USNM 648329. Scissmw’lla (Annturma) cqualm‘ia Hedley (p. 27). Height 0.6 mm, X 20. Drill hole on Funafuti Atoll, depth 65 ft; Recent. MCZ 28021. Emarginula (Emm‘ginuln) ()icam‘rllrzla Montrouzier (p. 27). Height 2.5 mm, X 10. Drill hole on Funafuti Atoll, depth 65—74 ft; Recent. British Mus. 1964, 23. Emarginula (Ernnrg/inula) (-f. E. pcnxct (Thiele) (p. 28). Length 3.3 mm. X 10. Drill hole E—1, Eniwetok Atoll, depth 90—110 ft; Recent. USNM 648231. Emarginula (Enmryinuln) aff. E. ('lypcus A. Adams (p.28). Length 4.3 mm, X 10. Drill hole F—1, Eniwetok Atoll, depth 60‘70 ft; Recent. USNM 648232. E'mm‘g'inulu (Subzcirlmvz) .s'rmvcrbimza Pilsbl'y (p. 28). Length 3.0 mm, X 10. Drill hole E—l, Eniwetok Atoll, depth 10—20 ft; Recent. USNM 648233. lt'murginulrl (Subzt'idm'n) sp. A (p.28). Length 2.1 mm, X 15. Drill hole 2B, Bikini Atoll, depth 1,807—1,819 ft; early Miocene (Tertiary e). USNM 648234. Emaryimda (Suhzcirlnm) sp. B (p. 29). Length 2.2 mm, X 15. Drill hole F—l, Eniwetok Atoll, depth 20—45 ft; Recent. USNM 648235. Hr’mitomu (Hemilvmu) sp. (p. 29). Length 28.8 mm, X 1. Sta. 110B, Vanua Mbalavu, Fiji; Ndalithoni limestone; probably Pliocene (Tertialy h). USNM 648449. Hcmilomn (Montfm‘tia) bikinicnsis Ladd, n. sp. (1). 29). Holotype, length 4.8 mm, X 6. Drill hole 2, Bikini Atoll, depth 105 ft; Recent. USNM 648236. Homitnma (Montfort'ia) sp. A (p. 29). Length 3.0 mm, X 10. Drill hole E—l, Eniwetok Atoll, depth 35—40 ft; Recent. USNM 648237. Hcmilmna (Monlfurlisla) (‘ICCNNTCG (Ircdalc) (p. 30). Length (incomplete) 9.2 mm, X 3. From coral pit (USGS 21029) on Espiritu Santo, New Hebrides; Pleisto- cene or Recent. USNM 648238. Rimula cx‘qm'sila A. Adams (p. 30). Length 4.4 mm, X 8. Drill hole 2A, Bikini Atoll, depth 447—453 ft; probably Pliocene. USNM 648239. Rimuln sp. (p. 30). Length 1.9 mm, X 15. Drill hole E—l, Eniwetok Atoll, depth 10—20 ft; Recent. USNM 648240. Scutus (Nannosculum) sp. A (p. 31). Width 7.1 mm, X 4. Drill hole F—l, Eniwetok Atoll, depth 720—730 ft; late Miocene (Tertiary g). USNM 648241. Scullm (Nnmumculum) sp. B (p.31). Length (incomplete) 5.3 mm, X 4. Drill hole K—lB, Eniwetok Atoll, depth 768—779 ft; late Miocene (Ter- tiary g). USNM 648242. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 2 GASTROPODS: HALIOTIDAE, SCISSURELLIDAE, AND FISSURELLIDAE FIGURES 1, 2. 3, 4. 5, 6. 7. 9, 10. 11—13. 14—16. 17—19. 20—22. 23, 24. 25, 26. 27, 28. 29. 30. 31. PLATE 3 Dior/om (Elcgitliou) 'murshallensis Ladd, n. sp. (p. 31). Holotype, length 3.4 mm, X 15. E—l, Eniwetok, 700—710 ft; late Miocene (Tertiary g). USNM 648243. Diodora (Elegidiun) aff. D. granifem (Pease) (p. 31). Length (incomplete) 3.0 mm, X 15. Mu—4, Eniwetok, 8 ft; Recent. USNM 648244. Diodm'a (Elegidion) sp. A (p. 32). Length 14.8 mm, X 3. Palau; late Miocene (Tertiary g). USNM 648245. Patella (Sculcllastra) stellaejm‘mis Reeve (p. 32). Length 9.1 mm, X 5. F—23—C, Eniwetok, 85—88 ft; probably Recent. USNM 648246. Cellana sp. A (p. 32). Length 28.2 mm, X 1. USGS 17891, Saipan; probably Recent. USNM 648247. Euchelus (Euchelus) cf. E. quadricarinatux (Dillwyn) (p. 33). Height 3.7 mm, X 8. K—lB, Eniwetok, 663—674 ft; late Miocene (Tertiary g). USNM 648253. Euchelus (Herpetopoma) instrictus (Gould) (p. 33). Eniwetok specimen, height 4.1 mm, X 8. E——1, 30—40 ft; Recent. USNM,648254. Euchelus (Horpctopoma) instrictus su’uaensis Ladd, n. subsp. (p.33). Holotype, height 3.6 mm, X 8. Viti Levu, Fiji (sta. 160); early Miocene (Tertiary f). USNM 648255. Euchelus (l'aceuchelus) ngulalus Pease (p. 34). Eniwetok specimen height 3.0 mm, X 8. E-l, 40—50 ft; Recent. USNM 648256. Euchclus (Vaceuchelus) sp. A (p.34). Eniwetok specimen, height 2.8 mm, X 8. E—l, 30—40 ft; Recent. -USNM 648257. Hybochelus cancellatus mientalis Pilsbry (p. 34). Eniwetok specimen, height/(incomplete) 3.6 mm, X 8. E—l, 50—60 ft; Recent. USNM 648258. Hybuchelus kavmicus Ladd (p. 35). Holotype, height 10.2 mm. Diameter (incomplete) 12.2 mm, X 2. Ndalithoni Limestone, sta. 110B, Vanna Mbalavu, Fiji; probably Pliocene (Tertiary h). Rochester Univ. Mus. Nat. History 13045. Thalulia (Thalolia) bcraucnsis (Beets) (p. 35). Eniwetok specimen, height 5.2 mm, X 5. K—IB, 1,070—1,081 ft; early Miocene (Tertiary f). USNM 648259. ’I'lmlotia (’l’halulia) mi. ’1'. clungalus (Wood) (p. 35). Guam specimen, height 222 mm, X 2. Mariana Limestone; (USGS 20574); probably Pleistocene. USNM 648260. ’l'halutia (Beraua) sp. (p. 35). Saipan specimen, height 9.7 mm, X 3. Inequigranular facies, Tagpochau Limestone (USGS 17904); Miocene. USNM 648261. ’l'urcica (Perrinia) mowimmi Ladd, n. sp. (p. 36). Holotype, diameter 2.8 mm, X 10. Bikini reef; Recent. USNM 648262. PROFESSIONAL PAPER 531 PLATE 3 GEOLOGICAL SURVEY GASTROPODS: FISSURELLIDAE,PATELLIDAE, AND TROCHIDAE FIGURES 1—5. 6, 7. 8—10. 11—13. 14. 15. 16—18. 19. 20—22. 23. 24. 25. PLATE 4 ’I'zu'cica (Pcrrinia) murrisoni Ladd, n. 51). (p. 36). 1,2. Holotype, height 3.3 mm, X 10. Bikini reef; Recent. USNM 648262. 3—5. Drill hole 2B, Bikini, l,461—1,472 ft; early Miocene (Tertiary f). USNM 648263, X 10. Gibbula (Gibbula) cngebicnsis Ladd. n. Sp. (p.36). Holotype, height 2.9 mm, X 10. K—lB, Eniwetok, 926—936 ft; early Miocene (Tertiary f). USNM 648264. F()s.s-arina (Minupa) hoflmcisleri Ladd. n. sp. (p. 37). Holotype, height 4.1 mm, X 8. Mu—4, Eniwetok, 40 ft; Recent. USNM 648265. Fig. 10 uncoated to show color pattern. Aslele (Callie-tale) cugcbiensis Ladd. n. sp. (p. 37). Holotype, height 2.7 mm, X 10. K—lB, Eniwetok, 968—978 ft; early Miocene (Tertiary f). USNM 648266. Trachus (Trochus) maculatus Linnaeus (p. 37). Guam specimen, height 20.2 mm, X 2. USGS 20636; Mariana Limestone; Pliocene and Pleistocene. USNM 648248. Tmchm (’l'mchus) histiio (Reeve) (p.37). Height 11.2 mm, X 2. F—l, Eniwetok, 110—120 ft; probably Recent. USNM 648249. 'I‘mchus (True/um) tubijems Kiener (p.38). Height (incomplete) 20.8 mm. X 2. Tongatabu, Tonga. (sta. 2); probably Pleistocene. B. P. Bishop Mus. geology No. 1339. (‘lrmculus (Clanculus) clnnguluides fijimlxis- Ladd (p. 38). Holotype, height 9.6 mm, X 3. Vanua Mbalavu, Fiji (sta. 110B); Ndalithoni Limestone; probably Pliocene (Tertiary h). Rochester Univ. Mus. Nat. History 13044. 'l'cclus (Teclus) maurii‘ianus (Gmelin) (p. 38). Height (incomplete) 16.5 mm, X 2. Espiritu Santo. New Hebrides (USGS 21028); probably Pleistocene. USNM 648250. ’ 'I't'ctus (Tmtus) of. 'I'. bomflxcnles‘ (Martin) (p. 39). Holotypo. height 15.1 mm, X 2. Viti Levu, Fiji (stzi. MR—20); probably Pliocene (Tertiary hr). USNM 648251. Tor/us (Rachiu) Milo/[CNN (Linnaeus) (p. 39). Height (incomplete) 100 mm. X 0.75. Espiritu Santo, New Hebrides (USGS 21029); Pleistocene or Recent. USN M 648252. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 4 GASTROPODS: TROCHIDAE FIGURES 1—4. 5—8. 9—12. 13, 14. 15,16. 17, 18. 19. 20—23 . 24. 25, 26. 27,28. 29, 30. 31—34. PLATE 5 Isamln (Purminuliu) upicina (Gould) (p. 39). 1,2. Height 3.9 mm, X 6. Eniwetok speciment, E—l, 60—70 ft; Recent. USNM 648267. 3,4. Height 4.9 mm, X 6. Gould’s type from Australia; Recent. USNM 24159. Mrmilm (Monilca) matcana Ladd (p. 40). 5,6. Holotype, height 7.0 mm, X 4. Viti Levu, Fiji, (sta. 160); Miocene (Tertiary f). B. P. Bishop Mus. Geo]. 1196. 7,8. Specimen from type locality, height 6.7 mm, X 4. USNM 648392. Mnnilea (Monilm) marshallensis Ladd, n. sp. (1). 40). 9,10. Holotype, height 3.9 mm, X 6. K—lB, Eniwetok, 1,248—1259 ft; early Miocene (Tertiary e). USNM 648270. 11,12. Paratype A, height 4.1 mm, X 6. Bikini, core from depth 235 ft; post-Miocene. USNM 648268. Monilea (Mom'lea) lijuana Fischer (p.40). Eniwetok specimen, height 5.2 mm, X 4. En—4, 2 ft; Recent. USNM 648269. Monilea (Monilea) belcheri (Philippi) (p.41). Fiji specimen, height 8.6 mm, X 4. Sta. 320, Viti Levu, Fiji; Miocene. B. P. Bishop Mus., geology No. 1235. Pseudostomatella (Pseudostomatella) maculaca (Quoy and Gaimard) (p.41). Fiji specimen, height 10.5 mm, X 3. Sta. 110B, Vanua Mbalavu; Nadalithoni Limestone; probably Pliocene (Tertiary h). USNM 648271. Stumatia cf. S. phymotis Helbling (p. 41). Guam specimen, height 7.3 mm, X 3. USGS 20534; probably Mariana Limestone; Pliocene and Pleistocene. USNM 648272. Synaptocochlea concinna (Gould) (p.41). Eniwetok specimen, height 3.0 mm, X 10. F—l, 60—70 ft; probably Recent. USNM 648273. Figures 21 and 23 are uncoated and show color pattern. Symptocochlea rosacea (Pease) (p.42). Eniwetok specimen, length 4.5 mm, X 12. E—l, 30—35 ft; Recent. USNM 648274. Synaptocochlea lekdlekana (Ladd) (p. 42). Holotype, diameter 11.5 mm, X 3. Sta. 1100, Vanua Mbalavu, Fiji, Nadalithoni Limestone; probably Plio- cene (Tertiary h). Rochester Univ. Mus. Nat. History 13051. Synaptocochlea marshallensis Ladd, n. sp. (p. 42). Holotype, height 1.5 mm, X 12. Eniwetok, K—lB, 757—769 ft; late Miocene (Tertiary g). USNM 648275. Angaria (lelphimts (Linnaeus)? (p.42). Guam specimen, height 30.2 mm, X 1. USGS 20720; Alifan Limestone; (Tertiary g or h). USNM 648276. Anglmki (lelphinus (Linneaus) (p.42). Fijian specimens: 31, height 24.6 mm, X 1.7. 32—34, height 13.9 mm, X 2. Both specimens from sta. 160 on Walu Bay, Viti Levu; Suva Formation; (Tertiary f). Fig. 31 is B. P. Bishop Mus., geology No. 1216; figs. 32—34 are USNM 648393. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 5 GASTROPODS: TROCHIDAE, STOMATELLIDAE,AND ANGARIIDAE FIGURES 1—5. 10—12. 13—15. 16—18. 19, 20. 21—23. 24—26. 27—29 . PLATE 6 Astraea (Astralium) rhodostoma (Lamarck) (p.43). 1,2. Saipan specimen, height 29.1 mm, X 11/2. USGS 21407; Tanapag Limestone; probably Pleistocene. USNM 648285. 3—5. New Hebrides specimen, height about 25 mm, X 11/2. Unapong, Eromanga; Quaternary. Astraea (Astralium) aff. A. rhodostoma (Lamarck) (p. 43). Rubber cast, height 19.7 mm, X 11%.). From dolomitic limestone at depth of 1,006 ft. Main boring, Funafuti Atoll; probably Pleistocene. USNM 648286. Astraea (Astralium) em'wetokensis Ladd, n. sp. (p. 43). Holot-ype, height 7.9 mm, X 3. Drill hole F—1, Eniwetok, 790—800 ft; late Miocene (Tertiary g). USNM 648290. Astracn (Axlmlium) 'u‘lllllmlxix Ladd, 11. Sp. (1). 43). ' Holotype, height 12.9 mm, X 3. Viti Levu, Fiji (sta. 160); early Miocene (Tertiary f) USNM 648291. Astraea (Astralium) sp. A (p. 44). Eniwetok specimen, height (incomplete) 11.2 mm, X 3. F—l, 840—850 ft; late Miocene (Tertiary g). USNM 648292. Astraea (Astralium) sp. B (p. 44). Bikini specimen, height 1.8 mm, X 15. Drill hole 2, from core at 115 ft; Recent. USNM 648293. Astraea (Astralium) sp.‘ C (p.44). Eniwetok operculum, height 2.8 mm, X 5. K—lB, 937—947 ft; early Miocene (Tertiary f). USNM 648294. Astraea (Bellastraea) sp. D (p. 44), Holotype, height 1.1 mm, X 10. K—lB, Eniwetok, 841—853 ft; late Miocene (Tertiary g). USNM 648295. Astraea (Bellastraea) sp. E (p. 44). Eniwetok specimen, height 1.2 mm, X 10. K—lB, 1,196—1,207 ft; early Miocene (Tertiary e). USNM 648296. Astraea (Vitiastraea) holmesi Ladd, n. sp. (p.45). Holotype, height 2.4 mm, X 10. Viti Levu, Fiji (sta. 160); early Miocene (Tertiary f). USNM 648297. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 6 GASTROPODS: TURBINIDAE FIGURES 1-6. 7, 8. 9—11. 12—14. 15—17. 18—20. 21,22. 23. 24. 25, 26. 27. PLATE 7 Arene (Arene) metaltilmm Ladd, n. sp. (p. 45). 1—3. Holotype, height 1.2 mm, X 20. 2B, Bikini, 1,702—1,7l3 ft; early Miocene (Tertiary e). USNM 648298. 4—6. Paratype, height 1.2 mm, X 20. 2B, Bikini, 2,297—2,307 ft; early Miocene (Tertiary e). USNM 648299. Arene (Arene) sp. A (p. 45). Bikini specimen, height 2.3 mm, X 15. 2A, 742—747 ft; late Miocene (Tertiary g). USNM 648300. Liotina (Austroliotia) cf. L. botanica (Hedley) (p. 46). Holotype, height 1.4 mm, X 10. F-4—A, Elugelab, Eniwetok, 6—12 ft; Recent. USNM 648301. Liotina (Dentareue) loculosa (Gould) (p. 46). Eniwetok specimen, height 3.6 mm, X 6. 111—1, 110—120 ft; probably Recent. USNM 648302. Liotina (Dentarene) sp. A (p.47). Eniwetok specimen, height (incomplete) 1.9 mm, X 8. E—l. 2,590—2,600 ft; early Miocene, (Tertiary e). USNM 648303. Liotina (Dentarene) sp. B (p. 47). Bikini specimen, height (incomplete) 1.4 mm, X 8. 2B, 1,629—1,639 ft; early Miocene (Tertiary f). USNM 648304. Turbo (Turbo) petholatus Linnaeus (p.47). 21. Guam specimen, height (incomplete) 23.8 mm, X 11/2. USGS 20653; Agana Argillaceous Member of Mariana Limestone; Pliocene and Pleistocene. USNM 648277. 22. Guam specimen, height 29.4 mm, X 1%). USGS 20720; Alifan Limestone; (Tertiary g 01' h). USNM 648278. Turbo (Turbo) petholatus thanus Ladd (p.47). Fiji'specimen, height 23.2 mm, X 2. Sta. 160, Viti Levu; early Miocene (Tertiary f). USNM 648279. Turbo (Marmarustoma) chrysostnmus Linnaeus (p. 48). Guam specimen, height 22.0 mm. X 2. USGS 20636, Agana Argillaceous Member of the Mariana Limestone; Pliocene and Pleistocene. USNM 648280. Turbo (Marmarostoma) argyrostomus Linnaeus (p. 48). 25. Saipan specimen, height (incomplete) 59.5 mm, X 1. USGS 17387; Tanapag Limestone; Pleistocene. USNM 648281. 26. Guam specimen, height (incomplete) 62.6 mm, X 1. USGS 20679; Agana Argillaceous Member of Mari— ana Limestone; Pliocene and Pleistocene. USNM 648282. Turbo (Mm'marostoma) setosus Gmelin? (p. 49). Rubber cast from Funafuti, height 24 mm, X 11/2. Made from core piece 276 from depth of 526-546 ft; post-Miocene. USNM 648283. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 7 GASTROPODS: TURBINIDAE FIGURES 1, 2. 3,4. 5—7. 8—13. 14—22. PLATE 8 Turbo (Marmamstoma) crassus Wood (p. 49). Tonga specimen, height 79.3 mm, X 1. Near Houma, Tongatabu; probably Pleistocene. Turbo (Marmarostoma) sp. A (p.49). Fiji rubber cast and internal mold; height (of internal mold) 25.0 mm, X 11/2. Sta. 295,‘Viti Levu; Suva For- mation; early Miocene (Tertiary f). B. P. Bishop Mus, geology No. 1228. Cynisca pacifica Ladd, n. sp. (p. 49). Holotype, height 4.1 mm, X 8. E—l, Eniwetok, 1,000—1,010 ft; early Miocene (Tertiary f). USNM 648284. chtothym maculosa (Pease) (p. 50). Eniwetok specimen, height 1.7 mm, X 20. E—l, 40—45 ft; Recent. USNM 648305. Figs. 9, 11, 13 uncoated to show color pattern. Leptothyra mepta (Gould) (p. 50). 14—18. Eniwetok specimen, height 2.8 mm, X 10. Mu—4, 40 ft. 6 in. lo 41 ft; Recent. USNM 648306. Figs. 15 and 17 uncoated to show color pattern. 19—22. Gould’s type USNM 1372, height 2.3 mm, X 10. Kagoshima, Japan; Recent. Fig. 20 uncoated to show color pattern. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 8 GASTROPODS: TURBINIDAE FIGURES 1—3. 10—12. 13—15. 16—20. 21—23. 24—26. 27—29. PLATE 9 Leptothyra harlam' Ladd, n. sp. (p. 51). Holotype, height 1.9 mm, X .12. K—lB, Eniwetok, 663—674 ft; late Miocene (Tertiary g). USNM 648307. Leptothyra aff. L. laeta Montrouzier (p. 51). Eniwetok specimen, height 2.9 mm, X 10. K—lB, 957—968 ft; early Miocene (Tertiary f). USNM 648312. Loptothyra aff. L. candida (Pease) (p. 51). Eniwetok specimen, height 1.7 mm, X 15. BO—2—1, depth! 7 in.; Recent. USNM 648308. Leptothyra balnearii Pilsbry (p. 51). Eniwetok specimen, height 0.7 mm, X 15. F—l, 55—60 ft; Recent. USNM 648309. Leptothyra wellsi Ladd, n. sp. (p.52). Holotype, height 0.9 mm, X 25. F—l, Eniwetok, 690—700 ft; late Miocene (Tertiary g). USNM 648310. Leptothyra glarcosa marshallensis Ladd, n. subsp. (p. 52). 16—18. Holotype, height 2.3 mm, X 12. USNM 648313; 19—20. Operculum from paratype, USNM 648314, maximum diameter 1.1 mm, X 12; both Recent; Bikini lagoon, depth 30 fathoms. Leptothyra picta (Pease) (p.53). . Eniwetok specimen, height 2.1 mm. X 12. E—l, Eniwetok, 35-40 ft; Recent. USNM 648315. chtothyra emenana Ladd, n. Sp. (p. 53). Holotype, height 2.7 mm, X 12. F—l, Eniwetok, 940-950 ft; early Miocene (Tertiary f). USNM 648316. Leptothyra sp. A (p. 53). Eniwetok specimen, height 2.0 mm, X 12. K—lB, 642—653 ft; late Miocene (Tertiary g). USNM 648318. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 9 GASTROPODS: TURBINIDAE FIGURES 1—5. 6, 7. 10,11. 12—14. 15, 16. 17,18. 19. 20,21. 22. 23—25 . 26, 27. 28—31. PLATE 10 Gabrielona raunana Ladd, n. sp. (p. 54). 1,2. Holotype, height 1.4 mm, X 30. F—1, Eniwetok, 20—45 ft; Recent. Fig. 2 uncoated to show color pattern. USNM 648319. 3. Paratype A, height 2.0 mm, X 15. F—l, Eniwetok, 20-45 ft; Recent. USNM 648320. 4,5. Operculum, paratype C, maximum diameter 0.8 mm, X 40. F—15—A, Eniwetok, 26-29 ft; Recent. USNM 648322. Tricolia (Hiloa) variabilis (Pease) (p- 54). 6. Eniwetok specimen, height 1.4 mm, X 15. E—l, 30—40 ft; Recent. USNM 648323. 7. Eniwetok specimen, height 1.9 mm, X 15. E—l, 40—45 ft; Recent. USNM 648324. Assiminea nitz'da cniwetokensis Ladd, n. subsp. (p. 75). Holotype, height 1.8 mm, X 15. K—lB, Enwetok, 831—842 ft; early Miocene (Tertiary f). USNM 648325. Tricolia (Hiloa) sp. A (p.55). Fiji specimen, height 0.9 mm, X 30. Viti Levu (sta. 160); early Miocene (Tertiary f). USNM 648326. Phaswkmella sp. (p. 53). Eniwetok specimen, maximum diameter 3.4 mm, X 8. K—lB, 841—853 ft; late Miocene (Tertiary g). USNM 648327. Nerz'topsis (Neritopsis) raduvla Linnaeus (p. 55). Eniwetok specimen, height 2.8 mm. F—l, 960—970 ft; early Miocene (Tertiary f). USNM 648238. Figs. 12 and 13 are X 10; fig. 14 is X 15. Nerita (Amphinerita) insculpta Recluz (p.55). Eniwetok specimen, height 4.6 mm, X 5. F—l, 690—700 ft; late Miocene (Tertiary g). USNM 648332. Ncrita (Amphinerita) aff. N. polita Linnaeus (p.56). Holotype, height 3.4 mm, X 8. F—l, Eniwetok7 930—940 ft; early Miocene (Tertiary f). USNM 648333. Nerita (Ritena) palauensis Ladd, n. sp. (p.56). Holotype, height (incomplete) 17.3 mm, X 2. Auluptagel, Palau (USGS 23642); base of Palau Limestone; late Miocene. USNM 648330. Nerita (Thelioslyla) sp. A (p.56). Fiji specimen, height 11.3 mm, X 3. Viti Levu (sta. 95); probably Miocene. B. P. Bishop Mus, geology N0. 1195. Nerita (Theliostyla) Sp. B (p. 57). Fiji specimen, diameter 31.0 mm, X 1. Mango (sta. M2D); probably Miocene. USNM 648331. Neritina (Vitta) Walam'ensis Lesson (p. 57). 23,24. Guam specimen, height 6.3 mm, X 5. USGS 21377. USNM 648334. 25. Guam specimen, height (incomplete) 5.0 mm, X 5. USGS 20600; both specimens from Mariana Lime— stone; Pliocene and Pleistocene. USNM 648335. Neritilia traceyi Ladd (p.57). Holotype, height 1.9 mm, X 12. 2B, Bikini, 2,154—2,165 ft; early Miocene (Tertiary e). USNM 648336. Smnmgdia (Smamgdia) jugjacartensis (Martin) (p. 58). 28,29. Eniwetok specimen, height 5.2 mm, X 6. F—l, 830—840 ft; late Miocene (Tertiary g). USNM 648337. 30,31. Two specimens from hole K—lB on Eniwetok to show variation in color pattern. 30. From a depth of 841—853 ft; late Miocene (Tertiary g). USNM 648401, X 10. 31. From a depth of 873—884 ft; early Miocene (Tertiary f). USNM 648402, X 10. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 10 . w .- .. , . a .uy-"fi'flfin'lng 9".» 4 fiz’fJ'IV‘O-Q‘1wcu« , flf‘fl. ‘ GASTROPODS: PHASIANELLIDAE, NERITOPSIDAE, NERITIDAE, AND ASSIMINEIDAE FIGURES l, 2. 3, 4. 5—7. 8,9. 10. 11—13. 14, 15. 16,17. 18—20. 21,22. 23, 24. 25, 26. 27—31 . 32, 33. PLATE 1 1 Smaragdia (Smaragdia) jogjacartensis (Mart-in) (p.58). Palau specimen, height 2.6 mm, X 10. Goikul Peninsula, Babclthuap (USGS 21308); late Miocene (Tertiary g). USNM 648403. Smaragdia (Smamgdia) aff. S. rangiana (Récluz) (p. 58). Palau Specimen, height (incomplete) 3.2 mm, X 10. Goikul Peninsula, Babelthuap (USGS 21308); late Mio- cene (Tertiary g). USNM 648338. Smaragdia (Smuragdiu) colei Ladd, n. Sp. (p.58). 5,6. Holotype, height 5.6 mm, X 6. F—l, Eniwetok, depth 880—890 ft; early Miocene (Tertiary f). USNM 648339. 7. Paratype, height 3.8 mm, X 8. F—l, Eniwetok, depth 830—840 ft; late Miocene (Tertiary g). USNM 648405. Smaragdia (Smaragdia) Sp. A (p.59). Eniwetok specimen, height 1.4 mm, X 20. K—lB, 715—727 ft; late Miocene (Tertiary g). USNM 648340. Pisulina subpacifica Ladd, n. sp. (p. 59). Holotype, height 1.2 mm, X 20. 2B, Bikini, 789—799 ft; late Miocene (Tertiary g). USNM 648341. chtarius (Subtlilulcctarius) rehdcri Ladd, n. s]). (p. 59). Holotype, height 2.8 mm, X 12. 2A, Bikini, 1,051—1,057 ft; early Miocene (Tertiary f). USNM 648342. Iravadia gardnerae Ladd, n. sp. (p. 60). Holotype, height 3.3 mm, X 10. K—lB, Eniwetok, 831—842 ft; late Miocene (Tertiary g). USNM 648343. Putilla (Pseudosetia) momma Ladd, n. sp. (p.60). Holotype, height 1.1 mm, X 25. E—l, Eniwetok, 1,805—1,835 ft; early Miocene (Tertiary e). USNM 648344. Putilla (Parvisetia) goikulensis Ladd, n. Sp. (p.60). 18,19. Holotype, height 1.1 mm, X 30. USNM 648345. 20. Paratype, height 0.9 mm, X 30. Both specimens Goikul Peninsula, Babelthuap, Palau (USGS 21308); late Miocene (Tertiary g). USNM 648346. Putilla (Parcisetia) suvaensis, Ladd, n. sp. (p.61). Holotype, height 0.9 mm, X 30. Suva formation (stu. 178—20), Viti Lovu, Fiji; early Miocene (Tertiary f). USNM 648347. ’ Cingula (Peringiella) parryensis Ladd, n. Sp. (p.61). Holotype, height 1.7 mm, X 20. E—1, Eniwetok, 700—710 ft; late Miocene (Tertiary g). USNM 648348. Cingula (Peringiella) cf. 0. roseocincta (Suter) (p. 61). Palau specimen, height 1.0 mm, X 30. Goikul Peninsula, Babelthuap (USGS 21304); late Miocene (Tertiary g). USNM 648349. Amphithalmus (Ccrostmca) jeficoati Ladd, n. Sp. (p. 62). 27,28. Holotype, a smooth Shell, height 1.9 mm, X 15. E—l, Eniwetok, 840—850 ft; late Miocene (Tertiary g). USNM 648350. 29,30. Paratype A, a weakly ribbed shell, height 1.9 mm, X 15. K—lB, Eniwetok, 968—978 ft; early Miocene (Tertiary f). USNM 648351. 31. Paratype B,a strongly ribbed shell, height 2.3 mm, X 15. E—l, Eniwetok, 1010—1020 ft; early Miocene (Tertiary f). USNM 648352. Amphithalmus (Cerostraca?) myersi Ladd, n. sp. (p. 62). Holotype, height 1.5 mm, X 20. E—l, Eniwetok, 770—780 ft; late Miocene (Tertiary g). USNM 648353. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 11 31 GASTROPODS: NERITIDAE, LITTORINIDAE, IRAVADIIDAE,AND RISSOIDAE FIGURES 1. 4,5. 6, 7. 8,9. 10. 11,12. 13, 14. 15-18. 19. 20. 21,22. 23, 24. 25, 26. 27, 28. 29, 30. 31, 32. 33, 34. 35, 36. 37. PLATE 12 Amphithalmus (l’isinnu) bikiniensis Ladd, n. sp. (p. 62). Holotype, height 1.7 mm, X 20. 2B, Bikini, 1,839—1,850 ft; early Miocene (Tertiary e). USNM 648354. Alvam'a (Taramellia) corayi Ladd, n. sp. (p. 63). Holotype, height 1.6 mm, X 20. Mu—4, Eniwetok, 35—36 ft; Recent. USNM 648355. Alvam'a (Taramellia) kenneyi Ladd, n. sp. (p.63). Holotype, height 0.8 mm, X 30. E—l, Eniwetok, 1,746—1,777 ft; early Miocene (Tertiary e). USNM 648356. Merelina. (Merelina) pisinna (Melvill and Standen) (p. 63). Eniwetok specimen, height 1.9 mm, X 15. E—l, 850—860 ft; late Miocene (Tertiary g). USNM 648357. Merelina (Linemera) telkibam Ladd, n. sp. (p.64). Holotype, height 1.9 mm, X 15. USGS 21301, Goikul Peninsula, Babelthlmp. Palau; late Miocene (Tertiary g). USN M 648358. Parashiela beetsi Ladd, n. sp. (p. 64). Holotype, height 1.4 mm, X 20. F—8—C, Eniwetok, 19—22 ft; Recent. USNM 648368. Zebina (Cibdezebina) metaltilana Ladd, n. sp. (p. 64). Holotype, height 3.5 mm, X 10. 2B, Bikini, 1860—1870 ft; early Miocene (Tertiary e). USNM 648359. Zebina (Morehiella) cf. Z. cooperi (Oliver) (p. 65). Eniwetok specimen, height 5.7 mm. E—l, 110—120 ft; Recent. USNM 648361. Fig. 11, X 6; fig. 12, X 12. Zebina (Marchiella) killeblebana Ladd, n. sp. (p. 65). 13. Holotype, height 5.6 mm, X 6. E—l, Eniwetok, 960—970 ft; early Miocene (Tertiary f). USNM 648363. 14. Paratype, height 3.2 mm, X 8. F—l, Eniwetok, 930—940 ft; early Miocene (Tertiary f). USNM 648364. Zebina (Ailinzebina) abrardi Ladd, n. sp. (p. 65). 15,16. Holotype, height 3.9 mm, X 8. Bikini lagoon at depth of 20 fathoms; Recent. USNM 648365. 17. Paratype A, height 2.9 mm, X 10. Err—4, Eniwetok, 11 ft; Recent. USNM 648366. 18. Paratype B, height (incomplete) 2.3 mm, X 10. 2B, Bikini, 1,450—1,461 ft; early Miocene (Tertiary e). USNM 648367. Zebina? sp. A (p. 66). Bikini specimen, height 2.7 mm, X 12. 2B, depth 2,112—2,128 ft; early Miocene (Tertiary e). USNM 648370. Rz‘ssoina (Schwartziclla) gracilis (Pease) (p.66). Tongan specimen, height 3.0 mm, X 10. Tongatabu at altitude of 35 ft (B. P. Bishop Mus, geology N0. 1340); probably Pleistocene. Rissoina (Schwartziella) aff. R. flexuosa Gould (p. 66). Eniwetok specimen, height 4.0 mm, X 8. E—l, 40—45 ft; Recent. USNM 648382. Rissoina (Schwartziella) aff. R. indrai Beets (p. 66). Eniwetok specimen, height 7.7 mm, X 5. F—l, depth 930—940 ft; early Miocene (Tertiary f). USNM 648383. Rims-oinn (Schwartzielln) mejilann Ladd. n. sp. (p. 67). Holotype, height 2.8 mm, X 12. K—lB, Eniwetok, 831—842 ft; early Miocene (Tertiary f). USNM 648384. Rissoina (Schwartziella) jirikana Ladd, n. sp. (p.67). Holotype, height 2.3 mm. X 15. 2B, Bikini; 1,440—1,451 ft; early Miocene (Tertiary c). USNM 648385. Rissoina (Schwartziella) rilebana Ladd, n. sp. (p.67). Holotype, height 3.1 mm, X 10. 2B, Bikini, 778—789 ft; late Miocene (Tertiary g). USNM 648386. Rissoina (Zebinella) emnanana Ladd, n. sp. (p. 67). Holotype, height 4.8 mm, X 8. E—l, Eniwetok, 1,010—1,020 ft; early Miocene (Tertiary f). USNM 648387. Risa-aim (Zcbinclla) tcnuislriata Pease (p. 68). Eniwetok specimen, height 5.5 mm, X 8. En—4, 51/2 ft; Recent. USNM 648388. Rissoina (Zebinella) aff. R. supracostata Garrett (p. 68). Eniwetok specimen, height (incomplete) 12.4 mm, X 5. E—l, depth 890—900 ft; early Miocene (Tertiary f). USNM 648389. Rismimt (Phosinclla) clnlhrata A. Adams (p. 68). New Hebredu specimen, described by Abrard, height (incomplete) 8.7 mm. X 4.6. Island of Malekula; Plio— cene. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 12 34 GASTROPODS: RISSOIDAE FIGURES 1, 2. 3, 4. 5—8. 9, 10, 17, 18. 11,12. 13—16. 19-21. 22—25. 26. 27, 28. 29. 30. 31, 32. 33. 34, 35. 36, 37. 38—40. PLATE 13 Rissoina (Phosinella) clathrata A. Adams (p. 68). Fijian specimen, height 7.2 mm, X 5. Suva Formation, Viti Levu, (sta. 160); early Miocene (Tertiary f). USNM 648391. Rissoina (Phosinella) briggsi Ladd, n. Sp. (p. 68). Holotype, height 4.3 mm, X 8. Goikul Peninsula, Babelthuap, Palau (USGS 21301; late Miocene (Tertiary g). USNM 648390. Rissoz'na (Phosinella) balteata Pease (p. 69). 5,6. Bikini specimen, height 3.7 mm, X 8. 2A, depth 38—40 ft; Recent. USNM 648394. 7,8. Eniwetok specimen, height 3.7 mm, X 8. E—l, depth 880—890 ft; early Miocene (Tertiary f). USNM 648395. Rissuinu (Phasinclla) bikiniensis Ladd, n. sp. (p. 69). 9, 10. Holotype, height 4.9 mm, X 8. 2A, Bikini, 1,056—1,063 ft; early Miocene (Tertiary f). USNM 648396. 17,18.Paratype, height 3.6 mm, X 6. E—1,Eniwetok, 1,746-1,777 ft; early Miocene (Tertiary e). USNM 648400. Rissoina (Phosinella) transenna Watson (p.69). Eniwetok specimen, height 3.6 mm, X 10. Mu—4, 40 ft; Recent. USNM 648397. Rissoina (Phosinella) alexisi Ladd, n. Sp. (p. 70). 13, 14. Holotype, height 2.7 mm. X 12. F—l. Eniwetok, l,110—1,120 ft; early Miocene (Tertiary e). USNM 648398. 15,16. Paratype, height 2.5 mm, X 12. F-l, Eniwetok, 1,100—1,110 ft; early Miocene (Tertiary e). USNM 648399. Itissoina (Rissoina) abbotti Ladd, n. Sp. (p. 70). 19. Holotype, height (incomplete) 4.9 mm, X 6. 2A, Bikini, l,061—1,067 ft; early Miocene (Tertiary f). USNM 648371. 20.21. Paratypc, height (incomplete) 8.1 mm, X 4. Goikul Peninsula, Babelthuap, Palau (USGS 21301); late Miocene (Tertiary g). USNM 648372. Ifissoina (Rissoina) mijana Ladd, n. Sp. (p. 70). 22,23. Slender Specimen, height 3.3 mm, X 10. K—lB, Eniwetok, 968—978 ft; early Miocene, (Tertiary f). USNM 648373. 24,25. Holotype, height (incomplete) 4.3 mm, X 8. E—l, Eniwetok, 880—890 ft; early Miocene (Tertiary f). USNM 648374. Rissoina (Rinsoina) ailinana Ladd, n. Sp. (p. 70). Holotype, height 3.0 mm, X' 10. E—1, Eniwetok, 1,925—1,955 ft; early Miocene (Tertiary e). USNM 648375. Riswina (Rissoina) lomaolana Ladd. n. Sp. (p. 71). Holotype, height 4.1 mm, X 8. K—lB, Eniwetok, 842—852 ft; late Miocene (Tertiary g). USNM 648376. Rissoina (Rissoina) goikulensis Ladd, n. sp. (p. 71). Holotype, height‘ 3.7 mm, X 8. Goikul Peninsula, Babelthuap, Palau (USGS 21304); late Miocene (Tertiary g). USNM 648377. Rissoina (Rissoina) waluensis Ladd, n. Sp. (p. 71). Holotype, height 3.8 mm, X 8. Walu Bay, Viti Levu, Fiji (eta. 160); Suva Formation, early Miocene (Tertiary f). USNM 648378. Rissoina (Rissoina) ekkanana Ladd, n. Sp. (p. 71). Holotype, height 3.2 mm, X 10. Mu—4, Eniwetok, 35 ft; Recent. USNM 648379. Rissoim (Rissoma) concinna A. Adams (p. 72). Eniwetok specimen, height (incomplete) 6.4 mm, X 6. E—l, 970-980 ft; early Miocene (Tertiary f). USNM 648380. Rissm'na (Rissoina) Sp. A (p. 72). Fiji specimen, height (incomplete) 4.8 mm, X 6. Walu Bay, Viti Levu (Sta. 160); Suva Formation, early Miocene (Tertiary f). USNM 648381. Rissoina (Rissolina) tuwicula Pease (p.72). Eniwetok specimen, height 2.7 mm, X 12. F—l, 20—45 ft; Recent. USNM 648407. Rissoina, (Rissolina) marshallensis Ladd, n. sp. (p. 73). 38,39. Holotype, height 5.0 mm, X 6. K—lB, Eniwetok, 894—905 ft; early Miocene (Tertiary f). USNM 648408. 40. Paratype A, height (incomplete) 3.8 mm, X 6. E—l, Eniwetok, 850-860 ft; late Miocene (Tertiary g). USNM 648409. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 13 GASTROPODS: RISSOIDAE FIGURES 1—4. 13.14. 15, 16. 17, 18. 19, 20. 21, 22. 23, 24. 25, 26. 27. 28, 29. 30, 31. 32, 33. 34, 35. PLATE 14 Rissoina (Rissolina) marshallensis Ladd, n. sp. (p. 73). l. Paratype B, height 7.4 mm, X 6. K-lB, Eniwetok, 1,049—l,060 ft; early Miocene (Tertiary j). USNM 648410. 2. Paratype C, height 4.2 mm, X 6. K—lB, Eniwetok, 842-852 ft; late Miocene (Tertiary g). USNM 648411. 3. Paratype D, height 3.8 mm, X 6. K—lB, Eniwetok, 936—947 ft; early Miocene (Tertiary f). USNM 648412. 4. Paratype E, height 5.2 mm, X 6. 2B, Bikini, l,020—1,100 ft; early Miocene (Tertiary f). USNM 648413. Rissoina (Rissolina) epha’milla Watson (p. 73). 5,6. Eniwetok specimen, height 3.0 mm, X 10. E—l, 850—860 ft; late Miocene (Tertiary g). USNM 648414. 7,8. Bikini specimen, height 2.9 mm, X 10. 2A, 447—453 ft; Pliocene (Tertiary h) or Pleistocene. USNM 648415. 11,12. Slender Eniwetok specimen, height 3.0 mm, X 10. E—l, Eniwetok, 530—540 ft; probably Pliocene (Ter- tiary h). USNM 648417. Rissoina (Rissolina) kickarayana Ladd, n. sp. (p. 74). Holotype, height 4.1 mm, X 10. Goikul Peninsula, Babelthuap, Palau (USGS 21301); late Miocene (Tertiary g). USNM 648416. Rissoina (Rissolina) herringi Ladd, n. sp. (p. 74). Holotype, height 4.8 mm, X 8. F—l, Eniwetok, 710—720 ft; late Miocene (Tertiary g). USNM 648418. Rissoina (Rissolimz) harti Ladd, n. sp. (p. 74). Holotype, height 3.2 mm, X 10. 2B, Bikini, 1,555—1,566 ft; early Miocene (Tertiary e). USNM 648419. Rissoina (Rissolina) boumeae Ladd, n. sp. (p.74). Holotype, hegiht 3.2 mm, X 10. Suva Formation, Viti Levu, Fiji (sta. FB-20); early Miocene (Tertiary f). USNM 648420. Rissoina (Rissolina) sp. B (p. 75). Fiji specimen, height (incomplete) 3.9 mm, X 8. Viti Levu (sta. 165); probably Miocene. USNM 648421. Rissoina (Rissolina) plicata A. Adams (p. 74). Eniwetok specimen, height (incomplete) 6.9 mm, X 6. F—l, 870—880 ft; early Miocene (Tertiary f). USNM 648422. [fissoina (Risa-(Jinn) ambigua (Gould) (p. 71). Eniwetok speciment, height 6.4 mm, X 6. Rujiyoru Island, Eniwetok; Recent. USNM 648423. Itissoina (Rissoina) ambigua, parryemis Ladd, n. subsp. (p. 72). Holotype, height (incomplete) 6.8 mm, X 6. E—l, Eniwetok, 620—630 ft; late Miocene (Tertiary g). USNM 648425. Barleeia (Barleeia) meiauhana Ladd, n. sp. (p.75). Holotype, height 0.9 mm, X 30. Goikul Peninsula, Babelthuap, Palau (USGS 21301); late Miocene (Tertiary g). USNM 648426. Haplocochlias sp. A (p. 76). Eniwetok specimen, height 1.2 mm, X 25. K—lB, 831—842 ft; late Miocene (Tertiary g). USNM 648427. Leucorhynchia caledom'ca Crosse (p. 76). Eniwetok specimen, height 1.4 mm, X 15. Eb—2, 21—211/2 ft; Recent. USNM 648428. Leucorhynchia crossei Tryon (p. 76). Eniwetok specimen, height 1.2 mm, X 15. 13—1, 35-40 ft; Recent. USNM 648429. Leucorhynchia? stephensoni Ladd, n. sp. (p.76). Holotype. height 1.0 mm. X 15. K—lB, Eniwetok, 1,249—1,259 ft; early Miocene (Tertiary e). USNM 648430. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE 14 GASTROPODS: RISSOIDAE AND ADEORBIDAE FIGURES l, 2. 3—5. 6—8. 9—11. 12—14. 15—17. 18—20. 21—23. PLATE 15 Leucorhynchia? lilli Ladd, n. sp. (p. 77). Holotype, height 1.6 mm, X 15. Drill hole 1, Bikini, 40 ft; Recent. USNM 648432. Lophocochlias minutissimus (Pilsbry) (p. 77). Eniwetok specimen, height 0.5 mm, X 30. E—l, 710—720 ft; late Miocene (Tertiary g). USNM 648433. Lophocochlias paucicarinatus Ladd, n. sp. (p. 77). Holotype, height 1.0 mm, X 30. E—l, Eniwetok, 2,040—2,050 ft; early Miocene (Tertiary e). USNM 648434. Munditiella qualum (Hedley) (p. 77). Eniwetok specimen, height 1.0 mm, X 15. F—l, 280—290 ft; probably Pleistocene. USNM 648435. Munditiella parrycnsis Ladd, n. sp. (1). 78). Holotype, height 1.1 mm, X 15. E—l, Eniwetok, 35—40 ft; Recent. USNM 648436. Teinostoma (Esmeralda) engebiense Ladd, n. sp. (p. 78). Holotype, height 2.4 mm, X 15. En—4, Eniwetok, 1 ft; Recent. USNM 648437. ’l'einostuma (Esmeralda) marshallensc Ladd, n. Sp. (p. 78). Holotype, height 1.1 mm, X 15. K—1B, Eniwetok, 863—873 ft; early Miocene (Tertiary f). USNM 648438. Tcinostoma (Esmeralda) sp. A (p. 78). Fiji specimen, height 0.7 mm, X 20. Suva Formation, Viti Levu (sta. 160); early Miocene (Tertiary I). USNM 648439. GEOLOGICAL SURVEY PROFESSIONAL PAPER 531 PLATE l5 22 GASTROPODS: ADEORBIDAE FIGURES 1—3. 4, 5. 6—8. 9—11. 12—14. 15—17. 18—20. 21—23. PLATE 16 Solariorbis tricarinata (Melvill and Standen) (p. 79). Eniwetok specimen, height 1.6 mm, X 15. E—l, 990—1000 ft; early Miocene (Tertiary f). USNM 648440. Snlariorbis? sp. (p. 79). Fiji specimen, height 1.3 mm, X 15. Suva Formation, Viti Levu (sta. 160); early Miocene (Tertiary f). B. P. Bishop Mus. Geol. 1236. Lydiphnis cniwetokense Ladd, n. Sp. (p. 79). Holotype, height 1.8 mm, X 15. K-lB, Eniwetok, 936—946 ft; early Miocene (Tertiary f). USNM 648441. Cyclostremiscus emeryi Ladd, n. sp. (p. 80). Holotype, height 0.4 mm, X 30. E—l, Eniwetok, 780—790 ft; late Miocene (Tertiary g). USNM 648444. Cyclostremiscus (Ponocyclus) novemcarinatus Melvill (p. 80). Eniwetok specimen, height 1.0 mm, X 15. K—lB, 873—884 ft; early Miocene (Tertiary f). USNM 648442. Cyclostremiscus (Pnnocyclus) cingulifcm (A. Adams) (1). 80). Palau specimen, height 2.4 mm, X 10. Goikul Peninsula, Babelthuap (USGS 21304); late Miocene (Tertiary g). USNM 648443. Cochliolepis diangalana Ladd, n. sp. (p. 81). Holotype, height 0.8 mm, X 15. Goikul Peninsula, Babelthuap, Palau (USGS 21301); late Miocene (Tertiary g). USNM 648445. Vitrinella Sp. A (p. 81). Bikini specimen. height 0.9 mm, X 30. 2B, 1,723-1,734 ft; early Miocene (Tertiary c). USNM 648446. GEOLOGICAL SURVEY GASTROPODS: ADEORBIDAE PROFESSIONAL PAPER 531 PLATE 16 /4'. oéu ‘ m V a 3x