Latitude: 62°55'52"N
Longitude: 143°38'20"W
Location: This prospect is 1,000 feet north of the Mentasta Lake road and 2,100 feet northwest of the intersection of this road with the Glen Highway. It is at an elevation of about 2,700 feet in the SE1/4 of section 2, T. 13 N., R. 9 E. of the Copper River Meridian. It is locality 7 of Richter (1967) and locality 2 of Richter and others (1975). It is located to within a few hundred feet.
Geology: A thin band of serpentinite in Devonian metasedimentary rocks was prospected for asbestos in the 1950s by L. L. Patten (Richter, 1967). A dense, slightly schistose, and hard rock from one of the prospect pits was found to contain nephrite (jade). The nephrite is associated with roddingite inclusions and ranges in color from dark to light green with some apple-green zones. The deposit has produced a number of pounds of semiprecious stone (Richter and others, 1975). The alpine-type ultramafic body that hosts the deposit is Cretaceous (Richter, 1976).
Workings: Several small prospecting pits have been dug on this deposit.
Age: The serpentinite body that hosts the deposit is inferred to be Cretaceous (Richter, 1976).
Alteration: Serpentinization.
Production: The deposit produced a number of pounds of jadeite over 10 years before 1975 (Richter and others, 1975).
Commodities (Major) - Jade
Development Status: Undetermined.
Deposit Model: Serpentine-hosted asbestos (Cox and Singer, 1986; model 8d)
References
Richter, D.H., 1967, Geology of the upper Slana-Mentasta Pass area, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 30, 27 p., 2 sheets, scale 1:63,360. Richter, D.H., 1976, Geologic map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-932, 1 sheet, scale 1:250,000. Richter, D.H., Singer, D.A., and Cox, D.P., 1975, Mineral resources map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-655-K, 1 sheet, scale 1:250,000.
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