Unnamed (near Pinta Lake)

Occurrences, Probably inactive

Commodities and mineralogy

Main commodities Ag; As; Au
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PA
Quadrangle map, 1:63,360-scale D-4
Latitude 56.95967
Longitude -135.08162
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site consists of three quartz veins that were sampled by Bittenbender and others (1999). The veins occur along a trend that extends for about 1.5 mile northwest of Pinta Lake. The site is plotted in about the middle of these occurrences which is about 0.5 mile northwest the center of section 6, T. 57 S., R. 66 E.

Geologic setting

Geologic description

This deposit is one of many of similar deposits (PA002 to PA018) scattered over an area of about 6 square miles at the head of Silver Bay (Bittenbender and others, 1999). The deposits are gold-quartz veins with sparse sulfides, usually only pyrite and arsenopyrite. Samples that have been analyzed with modern methods usually show anomalous arsenic even if arsenopyrite is not identified in the rocks, and several parts per million mercury. The veins are often parallel to the bedding of the host rock which is graywacke and argillite of the Sitka Graywacke of Cretaceous age (Loney and others, 1975). Many of the so-called veins in the early literature are actually fault zones with lenses of quartz or concentrations of quartz stringers along the fault zone. Prospecting began in the area in 1871. The Stewart Mine (PA012) was located in 1872 and it was the first lode-gold mine in Alaska. The Silver Bay area has been prospected intermittently to the present but the veins are relatively small and most are low grade. The area has produced relatively little gold, many of the properties have not been active since before 1900, and there has been no production since the early 1940s.
There are no prospects known near this site. But Bittenbender and others (1999) found three quartz veins up to 6 feet thick along a trend that extends for about 1.5 miles northwest of Pinta Lake. Most of the veins have no sulfides and low precious metal values, but one sample collected near the outlet of Pinta Lake contained 205 parts per billion gold, 0.4 part per million (ppm) silver, and 2,550 ppm arsenic.
Geologic map unit (-135.083382934227, 56.9593022887889)
Mineral deposit model Low-sulfide, gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger based on the age of the host rocks.

Production and reserves

Workings or exploration Only surface sampling by government geologists.
Indication of production None
Reserve estimates None.

References

References

Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p.
Reporters Donald J. Grybeck (U.S. Geological Survey)
Last report date 2-Jan-05