Unnamed (coast, southeast of William Henry Bay) (ARDF #JU067) Au, Cu

Unnamed (coast, southeast of William Henry Bay)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Au; Cu
Other commodities	Co
Ore minerals	pyrite
Gangue minerals	calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale	JU
Quadrangle map, 1:63,360-scale	C-4
Latitude	58.7097
Longitude	-135.2199
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is on the west shore of Lynn Canal on the peninsula separating William Henry Bay from Lynn Canal. It is located in the NE1/4 section 34, T. 36 S., R. 61 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description This occurrence consists of a pyrite-bearing quartz-calcite vein in greenstone. The vein strikes NW and dips 70 NW, and is conformable to the foliation of the greenstone metavolcanic unit that hosts it. A sample of the quartz-calcite vein contained 2.7 ppm gold, 2,500 ppm copper, and 200 ppm cobalt. A sample of the greenstone contained 0.15 ppm gold, and 550 ppm copper (Clough and Redman, 1989). The general area is underlain by metamorphosed Silurian and Devonian clastic rocks, limestone, and volcanic units; Permian limestone and siltstone; and small plutons of Tertiary and Cretaceous granodiorite (Brew and Ford, 1985).
Geologic map unit	(-135.221712574368, 58.7093699858926)

Geologic description

This occurrence consists of a pyrite-bearing quartz-calcite vein in greenstone. The vein strikes NW and dips 70 NW, and is conformable to the foliation of the greenstone metavolcanic unit that hosts it. A sample of the quartz-calcite vein contained 2.7 ppm gold, 2,500 ppm copper, and 200 ppm cobalt. A sample of the greenstone contained 0.15 ppm gold, and 550 ppm copper (Clough and Redman, 1989). The general area is underlain by metamorphosed Silurian and Devonian clastic rocks, limestone, and volcanic units; Permian limestone and siltstone; and small plutons of Tertiary and Cretaceous granodiorite (Brew and Ford, 1985).

Geologic map unit

(-135.221712574368, 58.7093699858926)

Production and reserves

Workings or exploration	Surface sampling only.
Indication of production	None

References

References Brew, D.A., and Ford, A.B., 1985, Preliminary reconnaissance geologic map of the Juneau, Taku River, Atlin, and part of the Skagway 1:250,000 quadrangles, southeastern Alaska: U.S. Geological Survey Open-File Report 85-395, 23 p., 2 sheets, scale 1:250,000. Clough, A.H., and Redman, E.C., 1989, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984-1988, Volume 2, Detailed mine, prospect, and mineral occurrence descriptions, Section C, West Lynn Canal subarea: U.S. Bureau of Mines of Mines Special Publication, 44 p. Gehrels, G.E., and Berg, H.C., 1994, Geology of southeastern Alaska, in Plafker, George, and Berg, H. C., eds., The geology of Alaska: Geological Society of America, DNAG, The geology of North America, Vol. G-1, p. 451-467.
Reporters	J.C. Barnett and L.D. Miller (Juneau, Alaska )
Last report date	12/15/2001