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Unnamed (head of Kuskokwim River)

Occurrences, Inactive

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Commodities and mineralogy

Main commodities Au; Cu; Mo; Zn
Ore minerals arsenopyrite; chalcopyrite; pyrite; pyrrhotite; molybdenite; sphalerite
Gangue minerals ankerite; calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale LH
Quadrangle map, 1:63,360-scale B-2
Latitude 61.49
Longitude -153.4826
Nearby scientific data Find additional scientific data near this location
Location and accuracy
This occurrence is in the headwaters of the South Fork Kuskokwim River.
It is at an elevation of 4,000 feet along the south side of the river valley and 5.3 miles northeast of Snowcap Mountain. The map site is in the SE 1/4 section 12, T 16 N, R 24 W, of the Seward Meridian. This is locality 9 of Cobb (1972 [MF 412]; 1976 [OF 76-485]). The location is probably accurate to within one mile. Included with this location is a reported gold occurrence (Resource Associates of Alaska, 1976, p. 86) that is about 1 mile to the east, near peak 6425.

Geologic setting

Geologic description

Reed and Elliott (1970) reported that quartz float at this locality includes cobbles containing (1) as much as 40 percent disseminated pyrrhotite and minor chalcopyrite, (2) less than 2 percent molybdenite, and (3) 1- to 3-mm- wide veinlets with less than 10 percent sphalerite and pyrite. Samples contained as much as 12 ppm gold (Reed and Elliott, 1970; Gamble and others, 1989). Quartz veins 1 mile to the east, near peak 6425, are as much as 6 inches wide and contain arsenopyrite, pyrite, chalcopyrite, pyrrhotite, and as much as 2.3 ppm gold (Resource Associates of Alaska, 1976). These occurrences are near the contact of Tertiary diorite and quartz monzonite stocks with Cretaceous sedimentary rocks.
Geologic map unit (-153.484843819531, 61.4893569540709)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986, model 22c)
Mineral deposit model number 21c
Age of mineralization Tertiary. Quartz veins crosscut Tertiary intrusive rocks or nearby, thermally metamorphosed sedimentary rocks.
Alteration of deposit Silicification.

Production and reserves

Workings or exploration Reconnaissance sampling has been completed in this area (Reed and Elliott, 1970).
Indication of production None

References

MRDS Number A013066

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 70-271, 24 p., 4 sheets, scale 1:250,000.
Reporters Travis L. Hudson and Madelyn A. Millholland
Last report date 6/10/2001