Unnamed (south shore of Egg Island) (ARDF #SB024) Cu, Zn

Unnamed (south shore of Egg Island)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Cu; Zn
Other commodities	As
Ore minerals	galena; pyrite; sphalerite
Gangue minerals	calcite

Geographic location

Quadrangle map, 1:250,000-scale	SB
Quadrangle map, 1:63,360-scale	D-5
Latitude	55.822
Longitude	-159.352
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This site is located on the south shore of Egg Island in Humpback Bay on the Alaska Peninsula. It is referred to as SBRGX-50 in Wilson and others (1988, locality 24). The location is accurate to within 1,200 feet.

Geologic setting

Geologic description This occurrence is in an area mapped as Paleocene to Eocene Tolstoy Formation (Wilson and others, 1995). The occurrence consists of sandstone, shale, and coal beds that are cut by andesite sills and a hypabyssal andesite plug (Wilson and others 1988). Calcite veins occur in an intensely fractured zone in andesite. The veins are as much as 4 inches thick and contain galena, pyrite, and sphalerite, along with inclusions of brecciated andesite. The controlling fractures are probably localized along a thrust fault mapped through this area (Wilson and others, 1988). Samples collected by the U.S. Geological Survey were reported to be anomalous in arsenic, copper, and zinc (Wilson and others, 1988).
Geologic map unit	(-159.354052377721, 55.8212022622214)
Mineral deposit model	Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number	22c
Age of mineralization	Tertiary.

Production and reserves

Workings or exploration	Rock samples 84AWs170, 172-173, collected by the U.S. Geological Survey in the mid-1980s, were reported to be anomalous in arsenic, copper, and zinc (Wilson and others, 1988).
Indication of production	None
Additional comments This site is located on land interim-conveyed to, or patented by, the Bristol Bay Native Corporation.

References

MRDS Number	10308228
References Angeloni, L.M., Wilson, F.H., and Sutley, S.J., 1985, Map and tables showing preliminary rock geochemical data, Port Moller, Stepovak Bay, and Simonof Island quadrangles, Alaska: U.S. Geological Survey Open-File Report 85-470, 179 p., 1 sheet, scale 1:250,000. Wilson, F.H., Detterman, R.L., Miller, J. W., and Case, J.E., 1995, Geologic map of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigation Series Map I-2272, 1 sheet, scale 1:250,000. Wilson, F.H., White, W.H., and DuBois, G.D., 1988, Brief descriptions of mines, prospects, and mineral occurrences in the Port Moller and Stepovak Bay quadrangles, Alaska Peninsula: U.S. Geological Survey Open-File Report 88-666, 128 p., 1 plate, scale 1:250,000.
Reporters	S.H. Pilcher
Last report date	11/9/2000