Prieliminary Summary Feview of Thorium-Bearing Mineral Occ-Nces in Alaska

UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY W. E. Wrather, Director

GEOLOGICAL, SURVEY CIRCULAR

PRIELIMINARY SUMMARY FEVIEW OF THORIUM-BEARING MINERAL OCC-NCES IN ALASKA

By Robert G. Bab and Welmuth Wedow, Jr.

Thw report wncarna work done on behalf of the U. 8.Atomic Energy Cdonand ia published with the permhion of the Commineion

Wmd-hgbn, D. C., 1963

Free on amliation to the Geologid Survey, Wlahinotpn 26, D. C.

PRELIMINARY S-Y Rl3VIEW OF THORIUM-BEARING MINERAL OCCURRENCES IN ALASKA

CONTENTS Fage Fage

Abstract...... 1 Discussion of data--Continued Introduction...... 1 Thorium occurrences worthy of Discussion of data...... 2 possible further study--Continued Thorium-bearing minerals ...... 2 Buckland-Kiwalik district...... 5 Thorium occurrences worthy of Clem Mountain area...... 5 possible further study ...... 3 Hunter Creek-Connolly Creek- Salmon Bay area ...... 3 Fairhaven Creek area...... 5 Tobin Creek-Big Creek area...... 4 Granite Mountain area...... 5 Manley Hot Springs district...... 4 Darby Mountains district ...... 5 Eurekaarea, ...... 4 Tubutulik River area...... 5 Tofty tin belt...... 4 Golovin Bay area...... 5 Hot Springs Dome area...... 4 Cape Mountain area...... 6 Long area...... ,...... 4 Conclusions...... 6 Nixon Fork area...... 4 Literature cited...... 6 ILLUSTRATICN Fage

Flate 1. Map of Alaska showing location of thorium occurrences...... Inside back cover

TABLES Fage

Table 1. General descriptio? of thorium-bearing minerals belonging to species that are found in Alaska ..... 2 2. Cccurrences of thorium-bearing minerals in Alaska,...... 8

ABSTRACT The remaining occurrences of thorium-bearing minerals in Alaska are limited to placer deposits and Thorium-bearing minerals are known at 47 lo- disseminations of accessory minerals in granitic rocks. calities in Alaska. At these localities the thorium In most of these occurrences the thorium-bearing occurs as a major constituent or in minor amounts as minerals occur in only trace amounts and consequently an impurity in one or more of the following 12 minerals: warrant little further consideration. More data are allanite, columbite, ellsworthite, eschynite, gummite, needed to determine the possibilities of byproduct monazite, orangite, mrisite, thorianite, thorite, recovery of thorium-bearing minerals from several xenotime, and zircon. In addition other minerals, such of the gold and tin placers. as biotite and sphene, are rackioactive arld may contain thorium. Several unidentified niobate minerals with uranium or uranium and thorium as major constituents INTRODUCTION have been recognized at some localities. Before the beginning of the Trace Elements The distribution, by type of deposit, of the 47 program of the Geological Survey in 1944, little was thorium occurrences is as follows: lode, 3; lode and known about the occurrence of thorium-bearing placer, I; granitic rock, 3; granitic rock and related minerals in Alaska. Mertie (1925, p. 26~)lreported placer, 14; and placer, 26. Of the four lode occur - the presence of monazite in the placers of Big Creek rences only the radioactive veins at Salmon Bay in in the Chandalar district north of Fort Yukon. southeastern Alaska and the contact metamorphic Eschynite, xenotime, and monazite were identified in deposit in the Nixon Fork area of central Alaska the tin-bearing placers of the Manley Hot Springs warrant further consideration as possible commercial district west of Fairbanks (Mertie and Waters, 1934, sources, although insufficient data are available to pp. 229, 239-240). Durinq World War I1 determine whether these two deposits have such possibilities. 'see pge 11 for list of liccrature cited.

1 J. H. Skidmore (1944) reported to the Union Mines DISCUSSION CF DATA Development Corp. on the radioactivity of various Alaskan placers; he noted that concentrates from mining Thorium-bearing minerals operations on Sweepstakes Creek in the eastern Seward Peninsula were especially radioactive, Later work Twelve minerals containing thorium, either (Gault and others, 1946; Killeen and White, 1950) by as a major constituent or in minor amounts as the Geological Survey showed that the chief radioactive an impurity, are known in Alaska, These mineral in the concentrates from Sweepstakes Creek minerals are allanite, columbite, ellsworthite, and other nearby streams is uranothorianite. eschynite, gummite, monazite, orangite, par isite, thorianite, thorite, xenotime, and zircon. For Considerable information has been collected on the convenience of the reader, brief general the occurrence of thorium-bearing minerals during descriptions of these minerals, summarized from the course of the Survey's reconnaissance investiga- Ford (1932), Frondel and Fleischer (1950), tions for uranium in Alaska. All available data on George (1949), and Falache and others (1951) are thorium-bearing minerals in Alaska are now being given in table 1. It should be emphasized that compiled, and the purpose of this report is to present these mineral descriptions, particularly the a preliminary surr,mary of the data compiled to date. thorium percentages, refer to mineral occurrences The spectrographic and chemical analyses, and most outside Alaska; few data are available on the of the radiometric analyses and mineral identifications thorium-bearing minerals in Alaska beyond the used in this report, were made in the Trace Elements fact that their presence at a particular locality has Section Washington Laboratory; a few of the radiomet- been noted. In addition, other minerals, such as ric analyses and mineral identifications were made biotite and sphene, are radioactive and may contain by members of the Survey's Alaskan 'I'race Elements thorium. Several unidentified niobate minerals with Unit. This work was done on behalf of the Division of uranium or uranium and thorium as major constituents Raw Materials of the U. S. Atomic Energy Comrr~ission. have been recognized at some localities.

Table 1.--General description of thorium-bearing minerals belonging to species that are found in Alaska

Thorium Mineral Chemical composition (percent) Description

Hydrous silicate of as much as 3 Color: brown to black. aluminum, calcium, Luster: resinous to submetallic. and the cerium metals Fracture: uneven to subconchoidal. Habit: tabular, also Long and slender, also masslve. Specific gravity: 2.7-4.2. Nlobate of iroq and Color: black, grayish and brownish black. manganese. Luster: submetalllc to subresinous. Fracture: subconchoidal to uneven. Habit: short prismatic grains. Specific gravity: 5.2-7.9. Complex hydrous oxides Color: amber yellow to dark brown. of niobium, tantalum, Luster: adamantine. sodium, calcium, with Fracture: subconchoidal to splintery, hydroxyl and fluorine uneven. may contain as much Habit: rounded grains, also massive. as 17 percent uranium Specific gravity: 3.8-4.2. Complex oxide of nlc- Color: brownish yellow to black. bium, tantalum, and Luster: submetallic to resinous, nearly the rare earths with dull. varying amounts of Fracture: small conchoidal. thorium and uranium. Habit: mostly masslve, also prismatic. Specific gravity: 4.9-5.2. Uranium with minor much as 22 Color: orange, yellow, orange yellow. amounts of thorium, Luster: dull to greasy. lead, and hydroxyl. Fracture: uneven to subconchoidal. Habit: massive, dense, also in rounded or flattened masses or crusts. Speclflc gravity: 3.9-6.4. 3are-earth phosphate CoLol: yellowish or reddish brown, golden with some thoria and yellow. silica. Luster: resinous. Fracture: concholdal to uneven. Habit: small, often flattened grains. Specific gravity: 4.9-5.3. Table 1.--General description of thorium-bearing minerals belonging to species that are found in Alaska--Continued

Thorium Mineral Chemical composition (percent) Description Oranglte------Thorium silicate, a 63 Color: bright orang& or orange yellow. variety of thorite. Luster: vltreous to glassy when fresh, dull to greasy when altered. Fracture: conchoidal. Hablt: square prismatic crystals, also massive. Specific gravity: 4.1-6.3. Papisite------Fluocarbonate of calcium 0-? Color: brownish yellow, brown, wax :ellow. and the cerium group. Luster: vitreous to resinous. Fracture: subconchoidal to splintery. Habit: crystals small and slender, pyramidal or prismatic. Specific gravity: 4.4. Thorianite---- Oxide of thorium and 34-63 Color: black, brownish,or grayish. uranium. Luster: submetallic to dull or g~asy. Fracture: uneven to subconchoidal. Habit: cubic. SpBcific gravity: 9.3. Thorite------Thorium silicate------25-63 Color: commonly black, brown, less commonly green. Luster: vitreous to glassy when fresh, dull to greasy when altered. Fracture: conchoidal. Habit: square prismatic crystals, also massive. Specific gravity: 4.1-6.4. Xenotime------Essentially yttrium 0.4-3.3 Color: shades of brown, yellow, green, phosphate. grayish white, pink. Luster: resinous to dull or earthy. Fracture: uneven and splinter7 Habit: long or short prismatic crystals. Specific gravity: 4.5-4.6. Zircon------Zirconium silicate, Usually low, Color: various shades of red, brown, usually with some ferric but as much and gray when thorium bearing. oxide and often some as 13.1 Luster: usually dull or subreslnous thorium and uranium. when thorium bearing. Fracture: conchoidal. Habit: prismatic, commonly long, less commonly stout, also massive. Specific gravity: 3.6-4.7. --- Thorium occurrences worthy of minerals occur in more than trace amounts. The possible further study distribution by type of deposit of these 13 localities is as follows: Thorium is known to be present because of the identification of thorium-bearing minerals, or assumed ode ...... 1 to be present because of discrepancies between equiv- Lode and placer...... 1 alent uranium and uranium analyses, at 47 localities Graditic rock and placer...... 5 in Alaska. Fertinent data on these occurrences are placer...... 6 given in table 2, p. 4. The distribution of the 47 occurrences by type of deposit is as follows: Summary descriptions of these 13 localities are given below, Lode., ...... 3 Salmon Bay area Lode and placer...... 1 Granitic rock...... 3 In the vicinity of Salmon Bay (2 on pl. 1 and table 2) at Granitic rock and placer...... 14 the northern end of Prince of Wales Island, southeastern Flacer only...... 26 Alaska, radioactive hematite-carbonate veins cut meta- morphosed sedimentary rocks of Silurian age (Houston, Thirteen of these localities may be worthy of further 1952a, p. 13). Most of the veins areless than 5 inches study because samp$s from them have a relatively wide, but at one locality a vein 0 to 10feet wide is exposed high thorium content, or because thorium-bearing for about 300 feet. A sample from a 2- to 3-inch vein contains 0.07 percent equivalent uranium but only 0.003 draining the granite area of Hot Springs Dome percent uranium. The difference is probably due to tho- (Moxham, 1062b). The equivalent uranium content. rium. In addition to thehematite and carbonates, the of this granite averages 0.003 percent. veins contain small amounts of pyrite, and locally minor amounts or traces of purple fluorite, chalcedony, feld- Although the radioactivity of the heavy-mineral spar, and mica. Parisite (afluocarbonate of thecerium fractions (those,greater than 3.3 specific gravity) of metals) has been identified in samples from a 6- to 10-fool the placer concentrates from the Hot Springs Dome thick vein (Houston, 1952b). The radioactive elements area is in the 0. OX range of percent equivalent in these veins are thought to be substitutingfor iron in the uranium, one concentrate from a tributary of Hot hematite or carbonates or may also occur as im- Springs Slough on the south side of the Dome contains purities in the fluorite or prisite. 0.3 percent equivalent uranium, about 20 percent monazite, and 5 percent xenotime. Another concen- Tobin Creek-Biq Creek area trate from glacial material just east of Blowback Creek on the north side of Hot Springs Dome contains Flacer concentrates from the Tobin Creek-Big 0.155 percentequivalent uranium ,-nd about 20 percent Creek area (26 on pl. 1 and in table 2) of the Chandalar monazite. district on the south flank of the Brooks Range in northeastern Alaska contain as much as 15 percent Long area monazite (White, 1952), which is associated with variable amounts of hematite, pyrite, scheelite, In the Long area (31 on pl. 1 and in table 2) ar senopyrite, galena, chalcopyrite, and gold. The of the Ruby-Foorman district in central Alaska, maximum equivalent uranium content of any of the allanite and thorite are the chief radioactive minerals placer concentrates so far obtainedfrom the Chandalar found in granite and in placers derived from the district is 0.05 percent. The source of the monazite granite (White and Stevens, 1952b). The equivalent may be "a highly acidic granitic rock, possibly of uranium content of the granite averages 0: 005 percent; pegmatitic character" (Mertie, 1925, p. 263). heavy-mineral fractions (those greater than 2.8 specific gravity) of the placer concentrates contain Manley Hot Springs district as much as 1.6 percent equivalent uranium and average 0.3 percent equivalent uranium. The thorite Eureka area. --In the Eureka area (28 on pl. 1 content of the heavy-mineral fractions from both the and in table 2) of the Manley Hot Springs district in granite and placer concentrates ranges from a trace central Alaska, Moxham (195213) found monazite and to about 10 percent. radioactive zircon in granite at Elephant Mountain. This granite averases about 0.004 percent equivalent Qualitative spectrographic analysis of the thorite uranium. Concentrates from placers in the Eureka indicates uranium(?), thorium, and siliconas major area contain frorn 0.004 to 0.042 percent equivalent constituents; and calcium, iron, titanium, and yttrium as uranium and average about 0.02 percent equivalent minor constituents. Chemical analysis of the thorite shows uranium. The radioactivity is attributed mostly to the uranium content to be about 8 percent. No analytical thorium because monazite constitutes as much as 10 data are available on the allanite except that it gives a pos- percent of the concentrates and is the chief radioactive itive flux test for uranium. mineral. The monazite in the Eureka placers was probably derived from the granite at Elephant Mountain. Fork area

Toft tin belt --Concentrates frorn placers of Uranium-bear ing thorianite, allanite, and the To*ri9 on pl. 1 and in table 2), south- other radioactive minerals have been reported west of the Eureka area in the Manley Hot Springs from the Nixon Fork area (33 on pl. 1 and in district, contain rnonazite, xenotime, columbite, table 2) in central Alaska (White and Stevens, ellsworthite, eschynite, and radioactive zircon 1952a). The thorianite occurs in placers, where (Moxham, 195213). A concentrate from Idaho Gulch it is associated with uraniferous hematite, was found to contain as much as 2.3 percent equiva- malachite, sphene, and zircon. The concentrate lent uranium although generally the radioactivity of exhibiting the greatest radioactivity contains 0.078 the concentrates from the Tofty tin belt is in the O.OX percent equivalent uranium, most of which is range of percent equivalent uranium. Moxham (1952b) attributed to the uraniferous thorianite. The indicates that the eschynite contains less than 1 per- bedrock source of the radioactive minerals has cent thorium and no uranium; the columbite has an not been located. equivalent uranium content of about 0. I percent; the equivalent uranium content of the monazite does not Large fragments of an altered limestone on the exceed 1 percent; and the zircon averages about 0.07 dump of the Whalen mine contain a high percentage percent equivalent uranium. of radioactive allanite. The altered limestone is apparently closely associated with contact-met- The bedrock source of the radioactive minerals amorphic gold-copper ores along a contact be- in these concentrates has not been discovered but may tween limestone and rnonzonite. The altered lime- be a differentiate phase of the intrusive at Rough Top stone contains as much as 0.05 percent equivalent Mountain to the north or the granite at Hot Springs uranium, which is ascribed to thorium, because Dome to the south or both (Mertie and Waters, 1934, chemical analyses show a content of only 0.004 per- pp. 244-246). cent uranium. About a quarter of the altered limestone consists of minerals of greater than 2.8 Hot Springs Dome area. --In the Hot Springs specific gravity. Of this heavy fraction 98 percent Dome area (30 on pl. 1 and in table 2) monazite and is allanite; zircon, kyanite, and scheelite constitute xenotime are found in most of the placers of creeks the remaining 2 percent. Near the shaft of the Whalen mine a highly percent equivalent uranium have been obtained from altered phase of the limestone is exposed; it contains the placers of headwater tributaries of the Feace about 0.025 percent equivalent uranium and 0.002 per- River, Anzac Creek, Rube Creek, Sweepstakes Creek: cent uranium. The radioactive mineral here is parisite,, headwater tributaries of the Kiwalik River, South which in the samples taken, makes up about 95 percent Fork Quartz Creek, Cub Creek: and an unnamed of the heavy-mineral fraction (that greater than 2.8 tributary of West Fork Buckland River. In all the specific gravity) of the rock. radioactive concentrates the uranothorianite appears to be the main radioactive mineral. Although allanite Buckland-Kiwalik district is relatively abundant in a pegmatitic facies of the granitic rock near the top of Granite Mountain, and Clem Mountaln area. --Uranothorianite and traces of uranothorianite have been identified among traces of thorite have been identified in several placer the accessory minerals of a specimen of syenite from concentrates from the Clem Mountain area (36 on pl. 1 the north flank of Granite Mountain in the headwaters and in table 2) in the northern part of the Buckland- d Quartz Creek, no lode concentrations of the mdio- Kiwalik district (West ahd Matzko, 1952) of the east- active minerals have yet been found. However, several ern Seward Feninsula. placer concentrates from the extreme headwaters of the Feace River on the east flank of Granite Mountain Heavy-mineral fractions (those greater than 2.8 near the contacts between the andesite and syenite specific gravity) containing more than 0.025 percent have an equivalent uranium content of about 0.2 to equivalent uranium were obtained from concentrates about 0.8 percent or approximately 10 times that of of placers in Duck, East Clem, and West Clem Creeks. the average uranothorianite-bearing concentrates The heavy-mineral fraction with the greatest radio- found elsewhere in the eastern Seward Feninsula. activity (0. 106 percent equivalent uranium) was These more radioactive concentrates, particularly obtained on Duck Creek above the mouth of West Clem uranothorianite, contain a higher content of the radio- Creek. active minerals than the other radioactive concentrates; in addition they contain copper sulfide minerals, Although the source of the radioactive minerals silver, and bismuth, which have not been identified in is not known, it is likely that they are disseminated the average uranothorianite-bearing samples. The accessory minerals in the granitic intrusives that greater amount of uranothorianite and the occurrence form the backbone of the Buckland-Kiwalik divide, of minerals believed to be of hydrothermal origin in because the radioactive minerals are found only in the placers less than a mile from stream divides suggest creek gravels containing granitic pebbles, the presence of a lode containing radioactive minerals.

Hunter Creek-ConnoUy Creek-Fairhaven Darby Mountains district Creek area. --Flacer concentrates from creek gravels within the headwater drainage of Hunter, Connol.ly, Tubutulik River area. --The chief radioactive and Fairhaven Creeks (37 on pl. 1 and in table 2), minerals found in the placers of the Tubutulik River south of the Clem Mountain area, contain thorite, area (40 on pl. 1 arld in table 2), in the northeastern uranothorianite, gummite, and traces of orangite part of the Darby Mountains district in the eastern (West and Matzko, 1952). Concentrates with heavy- Seward Feninsula, are allanite and unidentified niobate mineral fractions containing more than 0.025 percent minerals (West, 1952). The heavy -mineral fractions equivalent uranium were obtained from numerous sites (those greater than 2.8 specific gravity) of the oon- in the Hunter Creek-Connolly Creek-Fairhaven Creek centrates contain as much as 0. 1 Percent equivalent area. The sample with the greatest radioactivity was uranium but average only about 0.02 percent equivalent taken on Muck Creek, a left-limit tributary of Hunter uranium. In three samples from the area the niobates Creek, and contslins 0. 16 percent equivalent uranium. are estimated to constitute from 5 to 10 percent of the heavy-mineral fractions of the concentrates. Quali- The bedrock source of the radioactive minerals tative spectrographic analyses show that in two is not certain but, as in the Clem Mountain area, is samples the niobates contain uranium as a major presumed to be the granitic rocks in-the drainage element with no thorium recognized; in the third basins of the streams with radioactive placers. The sample the niobate contains both uranium and thorium thorite and orangite apparently are restricted to the as major constituents. A spectrographic analysis of gravels in the headwaters of Fairhaven Creek, and the allanite in one sample shows thorium as a major the liranothorianite and gummite seem to be limited to constituent with no uranium found. The bedrock placers in the headwaters of Hunter and Connolly Creeks. source of the allanite is unknown but is assumed to be differentiate phases of granitic rock in the drainage Granite Mountain area. --Granite Mountain areas of the streams from which the samples were (38 on vl. 1 and in table 2) in the eastern Seward obtained. The presence of topaz and traces of cassit- ~eninsulais composed largely of a syenitic stock erite along with the niobates suggests that these which was intruded into a complex of andesitic flows minerals may be genetically related to lode tin occur- and intrusives (Gault and others, 1946; Killeen and rences. It is also possible that these minerals may White, 1950; West and Matzko, 1952). The average have originated in pegmatitas. radioactivity of the syenite is about four times that of the andesitic rocks. The chief radioactive minerals Golovin Bay area. --The most radioactive in placer and bedrock samples from the Granite minerals in various tvnes of alacers alona the east Mountain area are allanite, uranothorianite, t hor ite, shore of Golovin Bay "(42 on 61. 1 and in &le 2), in and gummite. The equivalent uranium content of the the western part of the Darby Mountains district, are heavy-mineral fractions (those greater than 2.8 allanite, monazite, and an unidentified niobat~mineral specific gravity) of the placer concentrates is generally (West, 1952). The equivalent uranium content, of the O.OX percent. Concentrates with more than 0.025 heavy-mineral fractions (those greater than 2.8 specific gravity) of concentrates from these placers granitic rocks. It is possible that thorium might be ranges from 0.001 to about 0.08 percent. obtained as a byproduct from gold or tin placer operations in the following localities: The niobate mineral has been recognized only in a concentrate from slope wash on the beach about Major thorium- midway between Cheenik and Mission Creeks. The bearing minerals sample location is near the contact of a younger granite with an older intrusive complex. The heavy- Tobin Creek-Big Creek Monazite mineral fraction of this concentrate has an equivalent area, Chandalar district, uranium content of about 0.08 percent and is the most northeastern Alaska. radioactive heavy-mineral fraction taken in the area. It is estimated that the unidentified niobate mineral Manley Hot Springs district, Columbite comprises about 5 to 10 percent of the heavy-mineral central Alaska. Ellsworthite fraction, which also contains minor amounts of Eschynite sphene, topaz, hematite, allanite, and scheelite. Monazite Qualitative spectrographic analysis of the niobate Xenotirne shows uranium and thorium as major constituents. Long area, central Alaska---- Thorite Farther south along the Golovin Bay coast monazite and traces of allanite are found in a slope- Nixon Fork area, central Uranothorianite wash concentrate of which the heavy-mineral fraction Alaska. contains about 0.05 percent equivalent uranium. This sample was taken near the contact of granite with an Buckland-Kiwalik district, Uranothorianite older intrusive complex. west-central Alaska Thorite (Seward Feninsula). The remaining radioactive concentrates from the Golovin Bay area have equivalent uranium contents Cape Mountain area, west- Monazite that range from about 0.01 to about 0.03 percent. central Alaska (Seward Xenotime This radioactivity is ascribed largely to traces of Fenins ula). uranium or thorium in minor amounts of allanite, sphene, and zircon. More data are needed, however, to determine the thorium potentialities of these placer localities. Cape Mountain area LITERATURE CITED The major radioactive minerals in placer con- oentrates from the Cape Mountain area (47 on pl. 1 Ford, W. E. , 1932, Dana's textbook of mineralogy, and in table 2), in the western Seward Feninsula, are 4th ed, , New York, John Wiley and Sons, Inc. monazite, xenotime, and zircon. The concentrates Frondel, J. W., and Fleischer, M., 1950, A contain as much as 0.9 percent equivalent uranium glossary of uranium- and thorium-bearing minerals: and average about 0.03 percent equivalent uranium U. S. Geol. Survey Circ. 74. which, because of the monazite content of the concen- Gault, H. R. , 1949, Trace elements reconnaissance trates, is ascribed mostly to thorium. The source in the Candle Creek area, Fairhaven district, Seward of the radioactive minerals is probably the granite Feninsula, Alaska: U. S. Geol. Survey Trace at Cape Mountain, although they may be ,genetically Elements Inv. Rept. 41. [Unpublished. ] related to the tin deposits in the area. Gault, H. R., Black, R. F., and Lyons, J. B., 1946, Preliminary report on trace elements investigations in the Sweepstakes Creek area, Koyuk district, CONCLUSICNS Seward Feninsula, Alaska: U. S. Geol. Gurvey Trace Elements Inv. Rept. 25. [Unpublished. ] At 47 localities Alaska thorium occurs as a George, D'Arcy, 1949, Mineralogy of uranium- and major constituent or in minor amounts as an impurity thorium-bearing minerals: b. S. Atomic Energy in one or several of 12 minerals, These minerals Comm. RMO-563. are allanite, columbite, ellsworthite, eschynite, Harder, J. O., andReed, J. C., 1945, Freliminary gummite,' monazite, orangite, parisite, thorianite, report on radioactivity of some Alaskan placer thorite, xenotime, and zircon. At some localities samples: U. S. Geol. Survey Trace Elements Inv. sphene and biotite are also radioactive and may con- Rept. 6. [Unpublished. ] tain thorium; unidentified niobate minerals with Houston, J. R. , 1952a, Ft. 4, Southeastern Alaska, uranium or uranium and thorium as major constituents -in Freliminary summary of reconnaissance for have also been recognized. Lode thorium occurrences uranium in Alaska, 1951: U. S. Geol. Survey Circ. warranting possible further consideration are in 196, pp. 13-17. radioactive hematite-carbonate veins in the Salmon 1952b, Interim report: radioactive Bay area on Frince of Wales Island, southeastern hematite-carbonate veins in the Salmon Bay area, Alaska; and in a contact zone between limestone and Frince of Wales Island, southeastern Alaska: U. S. rnonzonite in the Nixon Fork area in central Alaska. Geol. Survey Trace Elements Memo. Rept. Data on these two deposits, however, are not 356. [Unpublished. ] sufficient to determine their potentialities. Killeen, F. L., and Ordway, R. J., 1946, Trace elements investigations at Ear Mountain, Seward The remaining thorium occurrences of any sig- Feninsula, Alaska: U. S. Geol. Survey Trace nificance are in placers or as accessory minerals in Elements Inv. Rept. 27. [Unpublished. ] Killeen, F. L,,and White, M. G., 1950, Trace U. S, Geol. Survey Trace Elements Memo. Rept. elements reconnaissance on the South Fork of 235. [open file. ] Quartz Creek, northeastern Seward Feninsula, West, W. S., 1952, Reconnaissance for radioactive Alaska: U. S. Geol. Survey Trace Elements Inv. deposits in the Darby Mountains area, Solomon and Rept. 42, pt. 2. [Unpublished. ] Bendeleben quadrangles, Seward Feninsula, Alaska: Mertie, J. B., Jr., 1925, Geology and gold placers U. S. Geol. Survey Trace Elements Inv. Rept. 53. of the Chandalar district, Alaska: U. S. Geol. [In preparation. ] Survey Bull, 773-E, pp. 215-263. West, W. S., and Berlson, F. D., 1952, Reconnais- Mertie, J. B., Jr., and Waters, A. E., Jr., 1934, sance for radioactive deposits in the vicinity of Mineral deposits of the Rampart and IIot Springs Ketchikan, Goddard Hot Springs, Chichagof, Funter districts, Alaska, by J. B. Mertie, Jr. ; Flacer Bay, and Juneau, southeastern Alaska: U. S. Geol. concentrates of the Rampart and Hot Springs districts, Survey Trace Elements Inv. Rept. 189. by A. E. Waters, Jr. : U. S. Geol. Survey Bull. [In preparation. ] 844-D, pp. 163-246. West, W. S., and Matzko, J. J., 1950, Radiometric Moxham, R. M., 1952a, Pt. 3, Radioactive minerals and mineralogic studies of the granitic complex in in the Yakataga beach placers, in Reconnaissance the Cape Nome area, Seward Feninsula, Alaska: for radioactive deposits in south-central Alaska, U. S. Geol. Survey Trace Elements Inv. Rept. 45, 1947-49, U. S. Geol. Survey Circ. 184. pp. 11-14. pt. 2. [Unpublished, ] 195213, Reconr~aissancefor radio- 1952, Reconnaissance for radioactive active deposits in the Manley Hot Springs-Rampart deposits in the Buckland-Kiwalik district, Candle district, central Alaska: U. S. Geol. Survey Trace quadrangle, Seward Feninsula, Alaska: U. S. Geol. Elements Inv. Rept. 54. [Unpublished. ] Survey Trace Elements Jnv. Rept. 49. Moxham, R. M., and Nelson, A. E., 1952, Pt. 2, [Unpublished. ] Radioactive pegmatite minerals in the Willow Creek White, M. G., 1950, Radioactivity and mineralogy mining district, j~ Reconnaissance for radioactive of placer concentrates from the Fortymile district, deposits in south-central Alaska, 1947-49, U, S. Alaska: U. S. Geol. Survey Trace Elements Inv. Geol. Survey Circ. 184, pp. 7-10. Rept. 57-A. [unpublished. ] Moxham,R. M., and West, W. S., 1949, Trace elements 1951, Radioactivity in the l'Okpilak'l investigations in the Ser pentine-Kougarok area, gneissic grate, Mount Michelson area, north- Seward Feninsula, Alaska: U. S. Geol. Survey Trace eastern'Alaska: U. S. Geol. Survey Trace Elements Elements Inv. Rept. 39. [unpublished. ] Inv, Rept. 57-C. f Unpublished. 1 Falache, C., Berman, H.; and Frondel, C., 1951, 1952, ~adioactivi't~and mineralogy Dana's system of mineralogy, 7th ed., vol. 2, of placer concentrates from the Wiseman and New York, John Wiley and,Sons, Inc. Chandalar districts, Upper Yukon region, Alaska: Robinson, G. D., Wedow, Helmuth, Jr., and U. S. Geol. Survey Trace Elements Memo. Lyons, J. B. , 1946, Trace elements investigations Rept. 327. [Unpublished. ] in the Cache Creek-upper Feters Creekarea, Yentna White, M. G. , and Killeen, F. L., 1950, Radioac- district, Alaska: U. 8. Geol. Survey Trace tivity and mineralogy of concentrates from the Elements Inv. Rept. 26. [unpublished. ] placers of Julian, Moore, and Candle Creeks, and Skidmore, J. B , 1944, Freliminary reconnaissance the Cripple Creek Mountains, lower Yukon-Kuskokwim survey of Alaska placer deposits: Union Mines and Highlands region, Alaska: U. S. Geol. Survey Devel. Corp. [Unpublished. ] Trace Elements Inv. Rewt. 45. pt. 1. 1 Unpublished. 1 Wedow, Helmuth, Jr. , 1952, Reconnaissance for 1952, ~eEonnaissancef& radio- radioactive deposits in the Eagle-Nation area, Eagle active deposits in the vicinity of Flat, Iditarod and Charley River quadrangles, east-central Alaska: quadsangie, southwestern~laska:U. S. Geol. Survey U. S. Geol. Survey Trace Elements Inv. Rept. 56. Trace Elements Inv. Rept. 46. [unpublished. ] [In preparation. ] White, M. G., and Stevens, J. M. ,-1952a,Reconnais- Wedow, Helmuth, Jr., and Matzko, J. J., 1947, sance for radioactive deposits in the vicinity of the Trace elements reconnaissance along highways in Nixon Fork mines, Medfra quadrangle, central the Tanana and upper Copper River valleys, Alaska: Alaska: U. S. Geol. Survey Trace Elements Inv. U. S. Geol, Survey Trace Elements Inv. Rept. 38. Rept. 75. [~npreparation. ] [~npublished.] 1952b, Reconnaissance for radio- Wedow, Helmuth, Jr., and Tolbsrt, G. E., 1952a, active deposits in the Ruby-Foorman district, Radioactivity at the Copper Creek copper lode pros- Ruby quadrangle, central Alaska: U. S. Geol. Survey pect, Eagle huadrangle, east-central Alaska: Trace Elements Inv. Rept. 192. [~npreparation. ] U. S. Geol. Survey Trace Elements Inv. Rept. 195. White, M. G., and Tolbert, G. E., 1952, Radioactive [ Unpublished. ] granite in the Miller House-Circle Hot Springs area, 1952b, Reconnaissance for radio- east-central Alaska: U. S. Geol. Survey Trace active deposits in the Fortymile district, Eagle Elements Inv. Rept. 194. [Unpublished. 1 quadrangle, east-central Alaska: U. S. Geol. White, M. G., and West, W. S,, 1952, Freliminary Survey Trace Elements Inv. Rept. 196. summary of reconnaissance for uranium on the [In ] Seward Feninsula, Alaska, during 1951: U. S. Geol. Wedow, Helmuth, Jr., White, M. G., and Survey Trace Elements Memo. Rept. 322. Maxham, R. M., 1951, Interim report on an [Unpublished. ] apprais$l of the uranium possibilities of Alaska: r;i 8 -m * m CU rl rr\ rl 3 9 ! i 6. C mi $& 0 NO cd g B0 lnm CU rnd Ln 2 a;$ .- 9 c dS 1 I s, sd 0 P) 4:b; *d 9 9 a84 ame%. P" 8' E r]

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0 V1 V1 Concentrate con- Do. tains 0.044 percent thorium. HMF; as much as Robinson and othe-s, 1946, 0.064. pp. 22, 23, table 5. Concentrate con- Harder. and Reed, 1945, tains 0.03 per- PP- 59 17- cent thorium. Concentrate con- Harder and Reed, 1945, tains 0.044 per- PP. 5, 6, appendix. cent thorium.

G; 0.004------Wedow and Matzko, 1947, i PP. 31, 58. G; 0.004------Wedow and Matzko, 1947, PP. 31, 60.

HMF; as much as 1 Wedow and Matzko, 1947, 0.011, avg. 0.006. pp. 36, 63.

G; 0.004; m-P; Wedow and Matzko, 1947, as much as 0.02. PP- 27, 55-57. e W; as much as White, 1950; Wedou and 0.041. Tolbert, 1952b.

G; as much as 0.06, avg. 0.004; HMF-P; as much as 0.1 (approx.). G; as much as 0.005; Wedow and Tolbert, 1952b. HMF-P; as much as o -096. m- 0.013------.Wedow and Tolbert, 1952a.

See footnotes at end of table. Table 2. --Occwrences of thorlum-bearlng mlnerals in Alasxa--Continued

Nm: .Explanation of symbols used in rable. G: granitic rock. L: lode deposit. P: placer. HMF: heavy-mineral fraction {usually grracer rhan 2.8 specific gmv4ty). .., Lr' Lr' ?mi m? odq cd 0 6," 5 bb z 3 52"" 6 * * 2 a * g: 2..I '"" 2 GI Table 2.--Occurrences of thorium-bearing minerals in Alaska--Continued

Nm: Expdauatim d symbol. used in table. G: granitic roek. L: lcde deporit. . P: pIacer. HMF: iun~-mimralkactio. (udully greater than 2.8 spcific paw). Quadrangle rtkmces arc the new 1:250,000 Ahsku Recoanaissance Series, most of &cb arc available at lnst in pfcopy. 47. Cape Mountain area------x ------X X -- GP HMF; as much as Harder and Reed, 1945, much as 0.9, p. 9. Also file data. avg. 0.03.

IAllanite occurs in sample from contact copper-iron ore; location in doubt. 2~arfsitenot known td be radioactive, study now in progress. 3~horiw.nmay be replacing Iron in hematite or carbonates. 4~adioactivehemstite -carbonate veins. hoother minerals belonging to zircon group. 60ther minerals are cgrtolite . Peptites. 6jor radioactive mineral is biotite;. radioactivity mostly due to uranium. g~adioactive mineral belonging to spinel group. 10~ontact-metamorphic zone be tween limes tone and monzonite . 11~eavy-mineral fractions containing more than 0.2 percent equivalent uranium restricted to headwaters of Peace River; 'other possible thorium-bearing mineral in Granite Mountain area is radioactive sphene. 12spectrographic analysis shows thorf um and no uranium. I3~h-e unidentiried. columbata mine~als;two with uranium and no thorium, one with both thorium and uranium as major constituents . 14~nidentifiedcolumbate mineral containing uranium and thorium as major constituents.