Greenpoint Prospect, Hyder District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA
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Location: The Greenpoint prospect is at an elevation of about 2700 feet on an untimbered point about 750 feet south of the confluence of Greenpoint and Through glaciers (Berg and others, 1977, p. 93-96; Elliott and Koch, 1981, p. 10, loc. 23). The location is probably accurate to within about a quarter of a mile. Also see Additional Comments field, below.
Geology: The country rocks in the area of the Greenpoint prospect are pelitic metasedimentary and andesitic metavolcanic rocks of the Jurassic or older Mesozoic Hazelton Group, and quartz monzonite and granodiorite of the Eocene Hyder Quartz Monzonite (Berg and others, 1977, p. 15-17, 22-23; Smith, 1977; Koch, 1996). The deposit (Berg and others, 1977, p. 93-96) consists of numerous quartz-calcite fissure veinlets up to 6 inches thick in multiple fracture sets that cut pelitic hornfels of the Hazelton Group. The veinlets contain up to 5% pyrite, lesser amounts of galena and molybdenite, and traces of chalcopyrite. Chip samples of the veinlets collected in 1972 by U.S. Bureau of Mines investigators contained as much as 30 ppm Ag. Average metal content was 2.4 ppm Ag, 400 ppm Pb, and 65 ppm Mo. One sample assayed 1100 ppm Zn.
Workings: Explored, probably in 1920's, by a small pit and open cut. Chip samples of veinlets collected in 1972 by the U. S. Bureau of Mines averaged 2.4 ppm Ag, 400 ppm Pb, and 65 ppm Mo. One sample contained 30 ppm Ag, and one assayed 1100 ppm Zn.
Commodities (Major) - Ag, Cu, Mo, Pb
Development Status: None
Deposit Model: Polymetallic veins
6 entries listed. 6 valid minerals.
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Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Kimball, A. L., 1977, Mineral resources of the Granite Fiords Wilderness Study Area, Alaska, with a section on aeromagnetic data by Andrew Griscom: U.S. Geological Survey Bulletin 1403, 151 p. Elliott, R.L., and Koch, R.D., 1981, Mines, prospects, and selected metalliferous mineral occurrences in the Bradfield Canal quadrangle, Alaska: U.S. Geological Survey Open-File Report 81-728-B, 23 p., 1 sheet, scales 1:250,000 and 1:63,360. Koch, R.D., 1996 [In press), Reconnaissance geologic map of the Bradfield Canal quadrangle, southeastern Alaska: U.S. Geological Survey Open-File Report, 1 sheet, scale 1:250,000. Smith, J.G., 1977, Geology of the Ketchikan D-1 and Bradfield Canal A-1 quadrangles, Alaska: U.S. Geological Survey Bulletin 1425, 49 p., 1 plate.