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Gemuk Mountain

Occurrence, Undetermined

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Commodities and mineralogy

Main commodities Au; Sb
Ore minerals gold; pyrite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale TA
Latitude 60.6
Longitude -159
Nearby scientific data Find additional scientific data near this location
Location and accuracy Gemuk Mountain is a 3,441 foot-high peak near the west boundary of the Taylor Mountains C-8 quadrangle. It is in the west headwaters of the Gemuk River. This occurrence is at an elevation of about 2,850 feet on a ridge a few thousand feet southwest of the summit of Gemuk Mountain. It is locality 6 of Clark and others (1970) and locality 5 of Cobb (1972 [MF 384]; 1976 [OF 76-606]).

Geologic setting

Geologic description

This occurrence is a mineralized shear zone between granitic rocks and thermally metamorphosed quartzite and shale (Clark and others, 1970). Discontinuous gold-bearing quartz-stibnite masses, 1- to 6-inches wide, occur as pods and lenses in fault gouge and breccia. Polished sections show the vein margins to be quartz and stibnite and the cores to be silificied fragments of biotite diorite in a quartz matrix. Pyrite is common at the margins of the silicified biotite diorite fragments. The mineralized zone trends N 50 W, is nearly vertical, and at least 2 feet wide. Native gold is at the margins of the stibnite-rich pods and lenses. Three vein samples contained gold values of 82, 94, and 100 ppm (Clark and others, 1970).
Geologic map unit (-159.002265428381, 60.5992756200437)
Mineral deposit model Simple Sb deposits (Cox and Singer, 1986; model 27d)
Mineral deposit model number 27d
Age of mineralization Late Cretaceous or Early Tertiary (?). Possibly the age of many granitic plutons in the region.

Production and reserves

Workings or exploration Surface examination and sampling has occurred, probably including some by private companies since that of Clark and others (1970).
Indication of production None

References

MRDS Number A013455

References

Clark, A.L., Condon, W.H., Hoare, J.M., and Sorg, D.H., 1970, Analyses of rock and stream sediment samples from the Taylor Mountains C-8 quadrangle, Alaska: U.S. Geological Survey Open-File Report 438, 89 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Taylor Mountains quadrangle: U.S. Geological Survey Miscellaneous Field Studies Map MF-384, 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 Dillingham, Sleetmute, and Taylor Mountains quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-606, 92 p.
Reporters Travis L. Hudson
Last report date 12/30/2000