Radovan; Greenstone claims Prospect, Nizina District, Valdez-Cordova Borough, Alaska, USA
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Location: This prospect is on the nose of the ridge between Radovan Gulch and Glacier Creek. It is at an elevation of about 3,550 feet, 1,800 feet east of Radovan Gulch in the NW1/4 of section 22, T. 5 S., R. 17 E. of the Copper River Meridian. This is locality 67 of MacKevett (1976) and it is accurately located. Cobb and MacKevett (1980) included this prospect under the name 'Radovan'.
Geology: The deposit at this prospect consists of a chalcocite-rich vein that contains lesser amounts of bornite, covellite, cuprite, enargite, malachite, and native copper; the vein is localized in a major normal-fault zone in Triassic Nikolai Greenstone (Sainsbury, 1951; MacKevett, 1976). The fault zone strikes N 15-26 E and dips 73 SE; locally it contains colloform calcite, dolomite and chalcedony (Sainsbury, 1951). The vein is 1 to 8 inches wide over 150 feet of slope distance, widens to 4 feet over a distance of 10 to 15 feet, and pinches out abruptly (Sainsbury, 1951). Samples of the mineralization contained up to 50 parts per million (ppm) silver, 0.07 ppm gold, more than 20,000 ppm copper, and 2,000 ppm manganese (MacKevett and Smith, 1968, samples 43-49). The wallrocks of the vein are silicified and epidotized (Sainsbury, 1951). This vein is located on same fault zone as the Radovan, Low Contact prospect (MC160). Copper mineralization is common in Nikolai Greenstone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Workings: The prospect was explored with surface cuts and by a 65-foot-long adit that trends S 3 W from a portal that is about 250 feet below and 200 feet north of the massive chalcocite in the fault (Sainsbury, 1951).
Age: Cretaceous? Copper mineralization is common in Nikolai Greenstone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Alteration: Silicification, epidotization.
Commodities (Major) - Ag, Cu
Development Status: Undetermined.
Deposit Model: Basaltic Cu (Cox and Singer, 1986; model 23)
12 entries listed. 11 valid minerals.
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Cobb, E.H., and MacKevett, E.M., Jr., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the McCarthy quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-885, 156 p. MacKevett, E.M., Jr., 1976, Mineral deposits and occurrences in the McCarthy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-773-B, 2 sheets, scale 1:250,000. MacKevett, E.M., Jr., and Smith, J.G., 1968, Distribution of gold, copper, and some other metals in the McCarthy B-4 and B-5 quadrangles, Alaska: U.S. Geological Survey Circular 604, 25 p. MacKevett, E.M., Jr., Cox, D.P., Potter, R.W., III, and Silberman, M.L., 1997, Kennecott-type deposits in the Wrangell Mountains, Alaska--High-grade copper ores near a basalt-limestone contact, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 66-89. Sainsbury, C.L., 1951, Geology of the Nelson and Radovan copper prospects, Glacier Creek, Alaska: U.S. Geological Survey Open-File Report 61, 18 p.