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Unnamed (upper Edgar Creek)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Au
Ore minerals chalcopyrite; malachite

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale C-2
Latitude 63.633
Longitude -147.903
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 5,500 feet, in the eastern headwaters of upper Edgar Creek, a tributary to the Yanert Fork River. The map site is in the NE1/4 of sec. 10, T. 15 S., R. 2 W., of the Fairbanks Meridian. The location is accurate to within 2000 feet. This is location 26 of Sherwood and others (1976).

Geologic setting

Geologic description

The country rocks in the area of this occurrence are the Devonian Yanert Fork sequence, consisting mainly of siliceous mudstone, argillite, slate, phyllite, semischist, and impure quartzite. Thin interbeds of banded metachert and metavolcanic rocks are also present (Wilson and others, 1998). The bedded rocks are cut by Triassic(?) gabbroic sills and dikes. The occurrence consists of disseminations of chalcopyrite and possibly other sulfide minerals, in the metasedimentary rocks near a gabbro sill. Locally, the copper mineral(s) are oxidized to malachite. Samples contained 4,700 ppm copper and 0.4 ppm gold (Sherwood and others, 1976).
Geologic map unit (-147.905294156011, 63.6325547763773)
Age of mineralization Possibly Triassic, assuming that the mineralization is related to the gabbro.

Production and reserves

Workings or exploration Surface samples only. Samples contained 4,700 ppm copper and 0.4 ppm gold (Sherwood and others, 1976).
Indication of production None

References

MRDS Number 10307543

References

Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Healy quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-1062, 113 p.
Sherwood, K.W., Craddock, Campbell, and Smith, T.E., 1976, Mineral occurrences in the upper Wood River, Edgar Creek, and West Fork Glacier areas, central Alaska Range: Alaska Division of Geological and Geophysical Surveys Special Report 14, 13 p.
Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 76 p., 3 sheets, scale 1:500,000.
Reporters N. Van Wyck (Stevens Exploration Management Corporation)
Last report date 4/7/2000