Copper King; Hector Group Prospect, Valdez Creek District, Matanuska-Susitna Borough, Alaska, USA
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Geology: Copper King is primarily a skarn prospect. The country rocks are hornfelsed Permo-Triassic calcareous siltstone and conglomerate that are intruded by Upper Cretaceous(?) quartz porphyry dikes. The deposit consists chiefly of massive chalcopyrite, pyrite, and pyrrhotite in a skarn zone 20 to 40 feet thick exposed for about 200 feet at the surface. Subsidary zones of quartz stockwork veining and of sulfide disseminations also occur (unpublished report by Addwest Minerals International Ltd., 1997). The pattern of mineralization suggests a zonal distribution of Cu around quartz porphyry intrusions. This is the only prospect in the district explored primarily for copper, and is also the only prospect in the area where arsenopyrite has not been found (Hawley and Clark, 1974). In addition, molybdenite is more abundant here than at the other prospects. Samples taken at various times contain as much as 7.34% copper, 4.9 ounces of silver per ton, and 0.22 ounce of gold per ton (Cobb, 1978: OFR 78-1062).
Workings: Workings include soil grids, 1,500 feet of trenching and 9 drill holes with over 1,700 feet completed. A limited, ground-based TEM survey has also been used to outline skarn zones. Samples taken at various times contain as much as 7.34% copper, 4.9 ounces of silver per ton, and 0.22 ounce of gold per ton (Cobb, 1978: OFR 78-1062).
Age: Late Cretaceous(?).
Alteration: Skarn zones contain diopside, epidote, sericite, and anhydrite.
Commodities (Major) - Ag, Au, Cu; (Minor) - Mo, Zn
Development Status: None
Deposit Model: Cu skarn (Cox and Singer, 1986; model 18b)
5 entries listed. 5 valid minerals.
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Balen, M.D., 1990, Geochemical sampling results from the Bureau of Mines investigations in the Valdez Creek mining district, Alaska: U.S. Bureau of Mines Open-File Report 34-90, 218 p., 2 plates, scale 1:250,000. Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p. Capps, S.R., 1919, Mineral resources of the upper Chulitna region: U.S. Geological Survey Bulletin 692-D, p. 207-232. Clark, A.L., and Cobb, E.H., 1972, Metallic mineral resources map of the Healy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-394, 1 sheet, scale 1:250,000. Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Healy quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-1062, 113 p. Hawley, C.C., and Clark, A.L., 1968, Occurence of gold and other metals in the upper Chulitna district, Alaska: U.S. Geological Survey Circular 564, 21 p. Hawley, C.C., and Clark, A.L., 1974 (1975), Geology and mineral deposits of the upper Chulitna district, Alaska: U.S. Geological Survey Professional Paper 758-B, p. B1-B47, 2 plates, scale 1:12,000 and 1:48,000. Kurtak, J.M., Southworth, D.D., Balen, M.D., and Clautice, K.H., 1992, Mineral investigations in the Valdez Creek mining district, south-central Alaska: U.S. Bureau of Mines Open-File Report 1-92, 659 p., 2 plates, scale 1:250,000. Ross, C.P., 1933, The Valdez Creek mining district, Alaska: U.S. Geological Survey Bulletin 849-E, p. 289-333.