Bornite, Ruby Creek Prospect, Shungnak District, Northwest Arctic Borough, Alaska, USA
Location: Location along Ruby Creek on the north side of the Cosmos Hills in T. 19 N., R. 9 E., Kateel River Meridian. Shown as locality 24 in Mayfield and Grybeck (1978). Location accurate to within 600 ft. (200 m).
Geology: Sulfide minerals form matrix of breccia replacement deposits in brecciated and intensely folded and faulted dolomite and limestone of the Devonian Bornite marble, a 3000-ft.-thick (1000 m) unit of carbonate rocks. Deposit is structurally and stratigraphically confined to a sequence of Devonian dolomite, limestone, and calcareous phyllite (Kennecott Exploration Co., written comm., 1997). The deposit is interpreted (Hitzman and others, 1986, p. 1644-1674) to have formed along a rifted continental margin in Late Devonian time. It occurs along a fault (?)-contolled margin of a carbonate bank adjacent to a shale-filled graben.
Workings: Exploration shaft, drifts on two levels, and extensive core drilling have been completed (Kennecott Exploration Co., written comm., 1997).
Age: Late Devonian
Reserves: Estimate by Kennecott Exploration Co. of 50 million tonnes averaging 1.2% Cu with 454,000 tonnes grading up to 4% Cu. Some samples reach 0.02% eU but the U content of the ore is apparently negligible (Matzko and Freeman, 1963). Undisclosed amounts of Zn and Co (Bundzten and others, 1996, p. 56).
Commodities (Major) - Cu; (Minor) - Ag, Au, Co, Pb, U, Zn
Development Status: No
Deposit Model: Kipushi
ReferencesBernstein, L.R., and Cox, D.P., 1986, Geology and sulfide mineralogy of the Number One ore body, Ruby Creek copper deposit, Alaska: Economic Geology, v. 81, p. 1675-1689. Bundtzen, T.K., Swainbank, R.C., Clough, A.H., Henning, M.W., and Charlie, K.M., 1996, Alaska's mineral industry, 1995: Alaska Division of Geological and Geophysical Surveys Special Report 50, 72 p. Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in northern Alaska: U.S. Geological Survey Open-File Report 75-628, 106 p. Cobb, E.H., and Mayfield, C.F., 1981, Summaries of data on lists of references to metallic and selected nonemetallic mineral occurrencs in the Ambler River quadrangle, Alaska; Supplement to Open-File Report 75-628; Part A, Summaries of data to January 1, 1981: U.S. Geological Survey Open-File Report 81-570-A, 13p. Fritts, C.E., 1970, Geology and geochemistry of the Cosmos Hills, Ambler River and Shungnak River quadrangles, Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 39, 63 p., 4 sheets, scale 1:63,360. Hitzman, M.W., Profett, J.M., Jr., Schmidt, J.M., and Smith, T.E., 1986, Geology and mineralization of the Ambler district, northwestern Alaska: Economic Geology, v. 81, p. 1592-1618. Hitzman, M.W., Smith, T.E., and Proffett, J.M., Jr., 1982, Bedrock geology of the Ambler district, southwestern Brooks Range, Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 75, 2 sheets, scales 1:125,000, and 1:166,667. Mayfield, C.F., and Grybeck, D., 1978, Mineral occurrences and resource map of the Ambler River quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-120-I, 1 sheet, scale 1:250,000. Matzko, J.J., and Freeman, V.L., 1963 Summary of reconnaissance for Uranium in Alaska, 1955: U.S. Geological Survey Bulletin 1155, p. 33-49. Runnels, D.D., 1969, The mineralogy and sulfur isotopes of the Ruby Creek copper prospect, Bornite, Alaska: Economic Geology, v. 64, p. 75-90. Sicherman, H.A., Russell, R.H., and Fikkan, P.R., 1976, The geology and mineralization of the Ambler district, Alaska: Spokane, Wash., Bear Creek Mining Company, 22 p.
var: Arsenian Renierite
16 entries listed. 15 valid minerals.
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