Unnamed Occurrence (ARDF - MG021; overlooking Cheeneetnuk River), McGrath District, Yukon-Koyukuk Borough, Alaska, USA
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Geology: The unnamed occurrence is a large zone of pyritic gossan in argillite of the Upper Paleozoic Mystic subterrane near the Cheeneetnuk Thrust Fault system (Gilbert, 1981; Wilson and others, 1998). The pyrite-rich gossan can be traced for more than 300 meters of strike length; mineralized widths were not determined. A Tertiary (37.8 Ma) granite is exposed about one quarter mile from the gossan (Gilbert, 1981). Four grab samples taken along the strike of the zone consistently yielded anomalous copper and silver with values of up to 224 ppm copper and 1.9 grams/tonne silver (Gilbert, 1981).
Workings: W.G. Gilbert sampled the gossan during geologic mapping for the Alaska Division of Geological and Geophysical Surveys in 1978 (Gilbert, 1981). Four grab samples taken along the strike of the zone consistently yielded anomalous copper and silver with values of up to 224 ppm copper and 1.9 grams/tonne silver (Gilbert, 1981).
Reserves: None.
Commodities (Major) - Cu; (Minor) - Ag
Development Status: No
Deposit Model: Polymetallic replacement (?) (Cox and Singer, 1986; model 19a).
Mineral List
1 entry listed. 1 valid mineral.
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References
Gilbert, W.G., 1981, Preliminary geologic map and geochemical data, Cheeneetnuk River area, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File Report 153, 12 p., 2 sheets, 1:63,360 scale. Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 76 p., 3 sheets, scale 1:500,000.
