Unnamed Occurrence (ARDF - ID149; southeast of summit of Granite Mountain), Iditarod District, Yukon-Koyukuk Borough, Alaska, USA
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Geology: This occurrence consists of a hematite-bearing, breccia zone of unknown size and orientation in shale and sandstone of the Upper Cretaceous Kuskokwim Group. It is about a mile southeast of the edge of the Granite Mountain pluton (Miller and Bundtzen, 1994; Bundtzen and Miller, 1997, and Bundtzen, Miller, and Gray, 2004). A grab sample of mineralization contained 450 parts per million (ppm) zinc, more than 10 ppm mercury, 400 ppm arsenic, 7.0 ppm bismuth, 22 ppm antimony, and 15.00 percent iron (McGimsey and others, 1988).
Workings: Samples were collected by the U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys in 1986 (McGimsey and others, 1988).
Age: Unknown; the nearby Granite Mountain pluton has a 40K/40Ar age of 62.6 Ma Bundtzen and Miller, 1997).
Commodities (Major) - As, Bi, Zn; (Minor) - Fe, Hg, Sb
Development Status: None
Deposit Model: Polymetallic vein (Cox and Singer, 1986; model 22c).
2 entries listed. 1 valid mineral.
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Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286. McGimsey, R.G., Miller, M.L., and Arbogast, B.F., 1988, Paper version of analytical results, and sample locality map for rock samples from the Iditarod quadrangle, Alaska: U.S. Geological Survey Open-File Report 88-421-A, 110 p., 1 sheet, scale 1:250,000. 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.