Silver Bay

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Au; Cu
Ore minerals chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PA
Quadrangle map, 1:63,360-scale D-4
Latitude 56.99577
Longitude -135.12908
Nearby scientific data Find additional scientific data near this location
Location and accuracy There is little recent information about the Silver Bay prospect and it was not located by Bittenbender and others (1999). It is probably about 0.9 mile northeast of Arguello Island and about 0.6 mile southeast of the center of section 19, T. 56 S., R. 65 E.

Geologic setting

Geologic description

This deposit is one of many of similar deposits (PA002 to PA018) scattered over an area of about six 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.
The Silver Bay prospect was first mentioned by Becker (1897) who described it as a quartz vein with pyrite and chalcopyrite in 'pyroclastic diorite' (which is probably graywacke). There was no work in progress then. The prospect was mentioned in several later publications until 1912 but with few details other than that some work was being done on it (Wright and Wright, 1905; Wright and Wright, 1906; Wright, 1907; Knopf, 1912). It could not be found by Bittenbender and others (1999) who listed it in their table of deposits in the area and located it on their map of them. It is probably similar to the other gold-quartz veins in the Silver Bay area.
Geologic map unit (-135.130843971171, 56.9954056159356)
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 A claim or claims active prior to 1912.
Indication of production None
Reserve estimates None.

Additional comments

MAS number: 0021160023.

References

MRDS Number A013366

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