Napoleon Creek Mine, Fortymile District, Southeast Fairbanks Borough, Alaska, USA
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| Latitude & Longitude (WGS84): | 64° 6' 26'' North , 141° 43' 51'' West |
|---|---|
| Latitude & Longitude (decimal): | 64.1072222222, -141.730833333 |
Location: Napoleon Creek is an east tributary of the South Fork of the Fortymile River about 7 miles northeast of Chicken. Placer tailings are shown on the U.S. Geological Survey 1:63,360-scale topographic map of the Eagle A-2 quadrangle (1956; revised in 1971). The coordinates correspond to the midpoint of the tailings shown near the mouth of Napoleon Creek in section 20, T. 27 N., R. 19 E., of the Copper River Meridian. The location is accurate. This record also includes references to additional placer workings shown approximately 1 mile upstream and to terrace gravels that were mined near the mouth of Napoleon Creek. This site is locality 96 of Burleigh and Lear (1994), locality 44 of Eberlein and others (1977), and locality 58 of Cobb (1972 [MF-393]).
Geology: The rocks in the upper part of Napoleon Creek consist of Paleozoic amphibolite-facies metamorphic rocks that have been intruded by undifferentiated Jurassic granitic rocks (Foster, 1976; Werdon and others, 2001). The Napoleon pluton crops out at the head of the creek; the lode gold deposit (EA115) within the pluton is the likely source for at least some of the placer gold in Napoleon Creek. Bedrock near the mouth of Napoleon Creek consists mainly of unmetamorphosed Tertiary conglomerate and lesser sandstone, tuff, and local coal-bearing units (Spurr, 1898; Foster, 1976). These Tertiary rocks are preserved within a fault-bounded, structurally down-dropped basin. Near the eastern fault contact of the Tertiary sedimentary rocks with the older metamorphic rocks, Tertiary gabbro bodies intrude both units (Mertie, 1938; Werdon and others, 2001). At the mouth of the creek the valley is about 90 yards wide and is bordered by steep conglomerate bluffs (Mertie, 1938). Near the mouth of Napoleon Creek, terrace gravels depositionally overlie the Tertiary conglomerate and occur as high as 200 meters above the creek (Pinney, 2001). Placer mining on Napoleon Creek occurred near the mouth of the creek, at a site approximately 1.5 miles upstream, and on terrace benches. Gravel in lower Napoleon Creek is approximately 8 to 18 feet thick,and the placer gold was mainly found on top of bedrock or in cracks within bedrock (Mertie, 1938). The gold is coarse grained and irregularly shaped. Nuggets heavier than 17 ounces have been recovered. Nuggets a half-inch in diameter or more are common, and the gold fineness is about 851 to 870 parts of gold per thousand (Mertie, 1938; Smith, 1941 [B 910-C]). In 1953, the gold being recovered had a fineness ranging from 870 to 872 parts of gold per thousand (Saunders, 1953). A high bench on the north side of the creek had rich pockets of gold on Tertiary bedrock. This bench is about 170 meters above Napoleon Creek (Yeend, 1992), and the gravels are approximately 40 meters thick. Vein quartz has been found in the stream gravels (Spurr, 1898). Spurr (1898) considered that the placer gold was derived from an older placer. The lode gold deposit within the Napoleon pluton (see EA115) at the head of the creek is a likely source for at least some of the placer gold in Napoleon Creek. Minor platinum has been found in Napoleon Creek. A likely source for the platinum is the Jurassic platinum-group-bearing clinopyroxenite bodies located on the ridge at the head of Napoleon Creek (Werdon and others, 2000). Placer gold on Napoleon Creek was first discovered in 1893 (Spurr, 1898); since then, gravels from both the active stream and high bench terraces have been mined. The creek was mined intermittently from around 1898 to at least 1936. Prospecting on benches, as well as open-cut mining near the mouth of the creek, occurred in 1912 (Ellsworth and Davenport, 1913). The north valley walls were being mined in 1936 (Mertie, 1938), and Foster (1969 [B 1271-G]) reportd that rich pay streaks were found on the high terrace. In 1969, Foster and Keith (1969) noted that the placer mine on the bench had been abandoned. In 1990, as well as from 1999 to 2001, there was an active placer mining operation on Napoleon Creek (Yeend, 1992). In 1896, the only paying claims were the two nearest the mouth where gold was first discovered (Spurr, 1898). By 1899, gold had been produced in commercial quantities (Brooks, 1900). Production on Napoleon Creek between 1904 and 1907, combined with that from Montana (EA067), Buckskin (EA113), Dome Creek (EA079), Eagle, and Twin Creeks, totaled about 122 fine ounces (Eberlein and others, 1977). Production from discovery to 1936 was worth about $200,000 (gold at $20.76 per ounce) (Mertie, 1938). The terrace 170 meters above Napoleon Creek yielded about 1,300 ounces of gold from an area no much larger than a quarter of an acre (Yeend, 1992).
Workings: Placer gold on Napoleon Creek was first discovered in 1893 (Spurr, 1898); since then, gravels from both the active stream and high bench terraces have been mined. The creek was mined intermittently from around 1898 to at least 1936. Prospecting on benches, as well as open-cut mining near the mouth of the creek, occurred in 1912 (Ellsworth and Davenport, 1913). The north valley walls were being mined in 1936 (Mertie, 1938), and Foster (1969 [B 1271-G]) reported that rich pay streaks were found on the high terrace. In 1969, Foster and Keith (1969) noted that the placer mine on the bench had been abandoned. In 1990, as well as from 1999 to 2001, there was an active placer mining operation on Napoleon Creek (Yeend, 1992).
Age: Quaternary.
Production: In 1896, the only paying claims were the two nearest the mouth where gold was first discovered (Spurr, 1898). By 1899 gold had been produced in commercial quantities (Brooks, 1900). Production on Napoleon Creek between 1904 and 1907, combined with that from Montana (EA067), Buckskin (EA113), Dome Creek (EA079), Eagle, and Twin Creeks, totaled about 122 fine ounces (Eberlein and others, 1977). Production from discovery to 1936 was worth about $200,000 (gold at $20.76 per ounce) (Mertie, 1938).
Commodities (Major) - Au; (Minor) - Pt
Development Status: Yes; small
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a).
Mineral List
1 valid mineral.
Regional Geology
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
| Quaternary 0 - 2.588 Ma | Unconsolidated surficial deposits, undivided Age: Pleistocene (0 - 2.588 Ma) Description: Pebble-cobble gravel with trace to some sand and silt forming bases for roads and airports and piled in active or former gravel pits, open-pit mines, and dredged areas. Well to poorly sorted. Surface smooth to irregular. Extent based primarily on distribution between July 1978 and August 1981 when the aerial photographs were taken Lithology: Unconsolidated Reference: Wilson, F.H., Hults, C.P., Mull, C.G, and Karl, S.M. (compilers). Geologic map of Alaska. doi: 10.3133/sim3340. U.S. Geological Survey Scientific Investigations Map 3340, pamphlet 196. [21] |
| Carboniferous - Devonian 298.9 - 419.2 Ma | unclassified; Metamorphic: undivided Age: Paleozoic (298.9 - 419.2 Ma) Description: Eastern Alaska, Yukon, Mackenzie region, Yukon-Tanana upland Comments: Orogen, magmatic arc/suite; Wilson & Hults, unpublished compilation, 2007-08 Lithology: Schist, gneiss, migmatite, diatexite, tectonite, mylonite, granulite Reference: J.C. Harrison, M.R. St-Onge, O.V. Petrov, S.I. Strelnikov, B.G. Lopatin, F.H. Wilson, S. Tella, D. Paul, T. Lynds, S.P. Shokalsky, C.K. Hults, S. Bergman, H.F. Jepsen, and A. Solli. Geological map of the Arctic. doi:10.4095/287868. Geological Survey of Canada Map 2159A. [2] |
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References
Brooks, A.H., 1900, A reconnaissance from Pyramid Harbor to Eagle City, Alaska, including a description of the copper deposits of the upper White and Tanana Rivers: U.S. Geological Survey Twenty-first Annual Report, p. 331-391, plate 2. Brooks, A.H., 1909, The mining industry in 1908: U.S. Geological Survey Bulletin 379-A, p. 21-62. Brooks, A.H., 1916, Mineral resources of Alaska, report on progress of investigations in 1915: U.S. Geological Survey Bulletin 642, 279 p. Burleigh, R.E., and Lear, K.G., 1994, Compilation of data for Phase I of the mineral resource evaluation of the Bureau of Land Management Black River and Fortymile subunits: U.S. Bureau of Mines Open-File Report 48-94, 116 p. Cobb, E.H., 1972, Metallic mineral resources map of the Eagle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-393, 1:250,000 scale, 1 sheet. Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p. Cobb, E.H., 1977, Summary of references to mineral occurrences in the Eagle quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-845, 122 p. Eberlein, G.D., Chapman, R.M., Foster, H.L., and Gassaway, J.S., 1977, Map and table describing known metalliferous and selected nonmetalliferous mineral deposits in central Alaska: U.S. Geological Survey Open-File Report 77-168-D, 132 p., 1 sheet, scale 1:1,000,000. Ellsworth, C.E., 1910, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 442-F, p. 230-245. Ellsworth, C.E., and Davenport, R.W., 1913, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 542-F, p. 203-222. Ellsworth, C.E., and Parker, G.L., 1911, Placer mining in the Yukon-Tanana region: U.S. Geological Survey Bulletin 480-F, p. 173-217. Foster, H.L., 1969, Reconnaissance geology of the Eagle A-1 and A-2 quadrangles, Alaska: U.S. Geological Survey Bulletin 1271-G, p. G1-G30. Foster, H.L., 1976, Geologic map of the Eagle quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series, Map 922, 1 sheet, scale 1:250,000. Foster, H.L., and Keith, T.E.C., 1969, Geology along the Taylor Highway, Alaska: U.S. Geological Survey Bulletin 1281, 36 p. Joesting, H.R., 1943, Strategic mineral occurrences in interior Alaska--Supplement to Pamphlet No. 1: Alaska Department of Mines Pamphlet 2, 28 p. Mertie, J.B., Jr., 1930, Mining in the Fortymile district: U.S. Geological Survey Bulletin 813-C, p. 125-142. Mertie, J.B., Jr., 1938, Gold placers of the Fortymile, Eagle, and Circle districts, Alaska: U.S. Geological Survey Bulletin 897-C, p. 133-261. Pinney, D.S., 2001, Surficial-geologic map of the Eagle A-2 quadrangle, Fortymile mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Preliminary Interpretive Report 2001-3c, 1 sheet, scale 1:63,360. Porter, E.A., 1912, Placer mining in the Fortymile, Eagle, and Seventymile River districts: U.S. Geological Survey Bulletin 520-G, p. 211-218. Powers, J.B., 1935, Brief history of the Fortymile and Eagle Mining Districts to 1935: Alaska Territorial Department of Mines Mineral Report MR 60-2, 19 p. Prindle, L.M., 1905, The gold placers of the Fortymile, Birch Creek, and Fairbanks regions, Alaska: U.S. Geological Survey Bulletin 251, 89 p. Prindle, L.M., 1906, Yukon placer fields: U.S. Geological Survey Bulletin 284, p. 109-127. Prindle, L.M., 1908, The Fortymile gold-placer district, in Brooks, A.H., ed., Mineral Resources of Alaska, Report on progress of investigations in 1907: U.S. Geological Survey Bulletin 345, p. 187-197. Prindle, L.M., 1909, The Fortymile quadrangle, Yukon-Tanana region, Alaska: U.S. Geological Survey Bulletin 375, 52 p. Smith, P.S., 1929, Mineral industry of Alaska in 1926: U.S. Geological Survey Bulletin 797, p. 1-50. Smith, P.S., 1930, Mineral industry of Alaska in 1927: U.S. Geological Survey Bulletin 810, p. 1-64. Smith, P.S., 1930, Mineral industry of Alaska in 1928: U.S. Geological Survey Bulletin 813, p. 1-72. Smith, P.S., 1932, Mineral industry of Alaska in 1929: U.S. Geological Survey Bulletin 824-A, p. 1-81. Smith, P.S., 1933, Mineral industry of Alaska in 1930: U.S. Geological Survey Bulletin 836-A, p. 1-83. Smith, P.S., 1933, Mineral industry of Alaska in 1931: U.S. Geological Survey Bulletin 844-A, p. 1-82. Smith, P.S., 1934, Mineral industry of Alaska in 1932: U.S. Geological Survey Bulletin 857-A, p. 1-91. Smith, P.S., 1934, Mineral industry of Alaska in 1933: U.S. Geological Survey Bulletin 864-A, p. 1-94. Smith, P.S., 1936, Mineral industry of Alaska in 1934: U.S. Geological Survey Bulletin 868-A, p. 1-91. Smith, P.S., 1937, Mineral industry of Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95. Smith, P.S., 1941, Fineness of gold from Alaska placers: U.S. Geological Survey Bulletin 910-C, p. 147-269. Spurr, J.E., 1898, Geology of the Yukon gold district, Alaska, with an introductory chapter on the history and conditions of the district to 1897 by H.B. Goodrich: U.S. Geological Survey 18th Annual Report, Part 3, p. 87-392. Werdon, M.B., Newberry, R.J., and Szumigala, D.J., 2001, Bedrock geologic map of the Eagle A-2 quadrangle, Fortymile mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Preliminary Interpretive Report 2001-3b, 1sheet, scale 1:63,360. Werdon, M.B., Szumigala, D.J., Newberry, R.J., Grady, J.C., and Munly, W.C., 2000, Major oxide, minor oxide, trace element, rare-earth element, and geochemical data from rocks collected in Eagle and Tanacross quadrangles, Alaska in 2000: Alaska Division of Geological and Geophysical Surveys Raw-Data File 2000-4, 27 p., 3 sheets, scale 1:63,360. Yeend, W.E., 1992, Gold placers, gold source, and high terrace gravels in the Fortymile River area, Alaska, in Bradley, D.C., and Ford, A.B., eds., Geological studies in Alaska by the U.S. Geological Survey, 1990: U.S. Geological Survey Bulletin 1999, p. 228-230.
