Exray (ARDF #JU113) Cu

Exray

Prospect, Inactive

Commodities and mineralogy

Main commodities	Cu
Other commodities	Ag
Ore minerals	chalcopyrite
Gangue minerals	calcite

Geographic location

Quadrangle map, 1:250,000-scale	JU
Quadrangle map, 1:63,360-scale	B-5
Latitude	58.4376
Longitude	-135.5364
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is at an elevation of 2,800 feet on the crest of the northwest-trending ridge 2 miles west of Excursion Inlet. It is in the NW1/4 NE1/4 section 5, T. 40 S., R. 60 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description The general area is underlain by deformed and metamorphosed Silurian or Devonian carbonate, clastic, and volcanic clastic rocks that have been intruded by Upper Jurassic and Lower Cretaceous granitic and dioritic rocks (Brew and others, 1992). The deposit was discovered about 1909 (Brew and others, 1978). It is in calcareous argillite and consists of chalcopyrite-bearing calcite veins, breccia zones, and limestone-calcite breccia veins. Samples contain up to 4,300 ppm copper (Brew and others, 1978). Early workings included several surface pits and trenches along the veins. Wells and others (1986) show six prospects in this area.
Geologic map unit	(-135.538215043803, 58.4372648850339)

Geologic description

The general area is underlain by deformed and metamorphosed Silurian or Devonian carbonate, clastic, and volcanic clastic rocks that have been intruded by Upper Jurassic and Lower Cretaceous granitic and dioritic rocks (Brew and others, 1992). The deposit was discovered about 1909 (Brew and others, 1978). It is in calcareous argillite and consists of chalcopyrite-bearing calcite veins, breccia zones, and limestone-calcite breccia veins. Samples contain up to 4,300 ppm copper (Brew and others, 1978). Early workings included several surface pits and trenches along the veins. Wells and others (1986) show six prospects in this area.

Geologic map unit

(-135.538215043803, 58.4372648850339)

Production and reserves

Workings or exploration	This deposit was discovered about 1909 and development work consists of several surface pits and trenches.
Indication of production	None

References

MRDS Number	A012110
References Brew, D.A., Himmelberg, G.R., Loney, R.A., and Ford, A.B., 1992, Distribution and characteristics of metamorphic belts in the southeastern Alaska part of the North American Cordillera--Metamorphic styles in young and ancient orogenic belts: Journal of Metamorphic Geology, v. 10, no. 3, p. 465-482. Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p., 7 sheets. Wells, D.E., Pittman, T.L., Brew, D.A. and Douglass, S.L., 1986, Map and description of the mineral deposits in the Juneau, Taku River, Atlin, and part of the Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 85-717, 332 p., 1 sheet, scale 1:250,000.
Reporters	J.C. Barnett and L.D. Miller (Juneau, Alaska )
Last report date	12/15/2001