Unnamed Occurrence (ARDF - LH017; head of Hartman River), McGrath District, Bethel Borough, Alaska, USA
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Geology: Reed and Elliott (1970) reported finding mineralized float boulders at this locality. The boulders include argillite cut by 6-inch-wide quartz veins containing arsenopyrite, pyrite, tourmaline, and chalcopyrite, as well as quartz porphyry cut by thin veinlets containing pyrite and sphalerite. Cobb and Reed (1981) reported that upper Mesozoic graywacke, shale, and argillite are cut by mineralized shear zones and faults that contain disseminated sulfides, narrow veins of massive sulfide minerals, and quartz veins with minor amounts of sulfide minerals. In addition to copper and zinc anomalies, samples contain as much as 70 ppm silver and 0.9 ppm gold. This mineralized area is about one mile from a small Tertiary granitic stock.
Workings: Reconnaissance sampling has been completed in this area (Reed and Elliott, 1970).
Age: Tertiary? Mineralization crosscuts Upper Mesozoic sedimentary rocks. Polymetallic mineralization in this region is commonly associated with Tertiary granitic rocks.
Alteration: Quartz and tourmaline veining.
Commodities (Major) - Ag, Au, Cu, Zn
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986, model 22c)
Mineral List
7 entries listed. 6 valid minerals.
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References
Cobb, E.H., 1972, Metallic mineral resources map of the Lime Hills quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-412, 1 sheet, scale 1:250,000. Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p. Cobb, E.H., and Reed, B.L., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska; Supplement to Open-File Report 76-485; Part A, Summaries to January 1, 1981: U.S. Geological Survey Open-File Report 81-1343-A, 25 p. Gamble, B.M., Bailey, E.A., and Reed, B.L., 1989, Gold occurrences near Snowcap Mountain, Lime Hills B-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 89-0646, 8 p. Reed, B.L., and Elliott, R.L., 1970, Reconnaissance geologic map, analyses of bedrock and stream sediment samples, and an aeromagnetic map of parts of the southern Alaska Range: U.S. Geological Survey Open-File Report 70-217, 145 p., 1 sheet, scale 1:250,000. (Also published as U.S. Geological Survey Open-File Report 413)