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.