Happy Creek Mine, Iditarod District, Yukon-Koyukuk Borough, Alaska, USA
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Geology: The Happy Creek alluvial placer deposit is on the western flank of Chicken Mountain in the Iditarod mining district (Bundtzen and others, 1992). The placer deposit consists of both ancestral fluvial gravels on terraces and alluvial placer gravels in and near modern Happy Creek (Bundtzen and others, 1992; Miller and Bundtzen, 1994; Miller, Bundtzen, and Gray, 2005). The upper Happy Creek alluvial placer is transitional into residual placer deposits on the Upgrade, Trail, and other claims (ID107) on the steep west flank of Chicken Mountain. Rich placer deposits mined early in the 20th Century were in discontinuous layers of sand and gravel on weathered bedrock underneath about 5 to 16 feet of unconsolidated colluvium and alluvium. The gold was fine-grained, little worn, and often showed crystal faces (Maddren, 1911). In later years, miners mined 12 to 32 feet of the poorly consolidated bedrock below the alluvium. In the 1970s, most of the gold recovered by the Fullerton brothers was about 200 mesh in size and was in nearly equant grains. In addition to native gold, the heavy minerals found in concentrate from Happy Creek include chromite, ilmenite, magnetite, zircon, cinnabar, fluorapatite, scheelite, argentiferous Pb-Sb sulfosalts, monazite, realgar, and probably cassiterite (Cobb, 1974 and 1976 [OFR 76-576]; Bundtzen and others, 1987). Zircon-rich concentrate from Happy Creek contained up to 7,300 parts per million (ppm) uranium and 130 ppm thorium (White and Killeen, 1953). The gold is from 862 to 884 fine. The mineralized gold-bearing quartz stockwork in intrusive rocks on Chicken Mountain are almost certainly the lode source of the gold mined in the placers of Happy Creek (Cobb, 1974; Bundtzen and others, 1992). Based on examination of published and unpublished records, Bundtzen and others (1992) estimated that Happy Creek produced at least 127,486 ounces of gold and 17,210 ounces of silver, mainly from 1910 to 1984.
Workings: Gold was first mined on the Summit claim in upper Happy Creek in August and September of 1910 (Maddren, 1911). Mining was by hand methods. The creek was mined nearly continuously from 1910 until 1966. A shortage of water and problems in mining the deeply weathered granite bedrock led operators to temporarily abandon the creek in the 1920s. In about 1929, Happy Creek was leased to the partnership of Andrew Olson, Tony Lindstrom, and Alex Palmgren who successfully mined it using a dragline feeding an elevated sluice box. Over the years, the size of the draglines increased. Olson and partners mined with a 1.5 cubic yard dragline; in 1970s, the Fullerton brothers mined with a 4.0 cubic yard dragline in the 1980s. In 1967, the U.S. Bureau of Mines in cooperation with the USGS drilled shallow auger holes in upper Happy Creek to test residual placers and explore for disseminated lode mineralization at the head of Happy Creek (Kimball, 1969).
Age: Probably Tertiary and Quaternary, by analogy with other placer deposits in Interior Alaska (Hopkins and others, 1971).
Production: Placer gold was produced nearly continuous from 1910 to about 1967; production resumed in 1975 and continued until 1984 (John and Richard Fullerton, oral communication, 1986). No production has been recorded since 1984. Production at the head of the creek was from residual or semi-residual deposits; the bedrock there consists of granitic slabs and disintegrated monzonite gruss (Cobb, 1974 and 1976 [OFR 76-576]). Production from fluvial gravels dominate in the lower end of the creek. The Fullerton Mining Company operated by John and Richard Fullerton conducted a highly successful mining operation from 1975 to 1984 and accounted for a significant percentage of total gold output. They used a portable elevated sluice box was fed by a large dragline. Based on examination of published and unpublished records, Bundtzen and others (1992) estimated that Happy Creek produced at least 127,486 ounces of gold and 17,210 ounces of silver, mainly from 1910 to 1984.
Commodities (Major) - Au; (Minor) - Ag, Cr, Hg, Sn, Th, U, W, Zr
Development Status: Yes
Deposit Model: Placer Au deposit (Cox and Singer, 1986; model 39a).
11 entries listed. 10 valid minerals.
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Bundtzen, T.K., Cox, B.C., and Veach, N.C., 1987, Heavy mineral provenance studies in the Iditarod and Innoko districts, western Alaska: Process Mineralogy VII, The Metallurgical Society, p. 221-246. Bundtzen, T.K., Miller, M.L., Laird, G.M., and Bull, K.F., 1992, Geology and mineral resources of Iditarod mining district, Iditarod B-4 and eastern B-5 quadrangles, southwestern Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 97, 46 p., 2 sheets, scale 1:63,360. Cobb, E.H., 1972, Metallic mineral resources map of the Iditarod quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-363, 1 sheet, scale 1:250,000. Cobb, E.H., 1974, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 pages. Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction material) in the Iditarod and Ophir quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-576, 101 p. Kimball, A.L., 1969, Reconnaissance sampling of decomposed monzonite for gold near Flat, Alaska: U.S. Bureau of Mines Open File Report 6-69, 39 p. Maddren, A.G., 1911, Gold placer mining developments in the Innoko-Iditarod region: U.S. Geological Survey Bulletin 480-I, p. 236-270. Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska showing potassium-argon, major oxide, trace element, fossil, paleocurrent, and archeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-A, 48 pages; 1 sheet, scale 1:250,000. Miller, M.L., Bundtzen, T.K., and Gray, J.E., 2005, Mineral resource assessment of the Iditarod quadrangle, west-central Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-B, scale 1:250,000, pamphlet. White, M.G., and Killeen, P.L., 1953, Reconnaissance for radioactive deposits in the lower Yukon-Kuskokwim highlands region, Alaska, 1947: U.S. Geological Survey Circular 255, 18 p.