Unnamed (southwest shore of Mitrofania Island)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Pb; Zn
Other commodities As; Sb
Ore minerals pyrite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SB
Quadrangle map, 1:63,360-scale D-3
Latitude 55.824
Longitude -158.899
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is on the southwest shore of Mitrofania Island about 0.6 mile southwest of the top of hill 1490. It is referred to as SBRX-43 in Wilson and others (1988, locality 17). The location is accurate to within 2,500 feet.

Geologic setting

Geologic description

This occurrence is in an area mapped as undivided Tertiary volcanic rocks (Wilson and others, 1995). Small plutons Miocene or Pliocene granodiorite to quartz diorite crop out a few miles to the north and south of the occurrence (Wilson and others, 1995). At this location altered andesite(?) flows are cut by numerous quartz-calcite veins as much as 6 inches thick (Wilson and others, 1988). Some of the veins are braided and contain pyrite and probably others sulfides. Rock samples collected by the U.S. Geological Survey were reported to be anomalous in silver, gold, lead, zinc, antimony, and arsenic (Angeloni and others, 1985; Wilson and others, 1988).
Geologic map unit (-158.901008113003, 55.8232136713513)
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 84AGe17-20 and 83AWs 63 collected by the U.S. Geological Survey in the mid-1980s, were reported to be anomalous in silver, gold, lead, zinc, antimony, and arsenic (Angeloni and others, 1985; Wilson and others, 1988).
Indication of production None

Additional comments

This site is located on land selected by the Bristol Bay Native Corporation.

References