Unnamed (near Lucky Chance Mountain)

Prospects, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities As
Ore minerals arsenopyrite; gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PA
Quadrangle map, 1:63,360-scale D-4
Latitude 56.94474
Longitude -135.04189
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site consists of several previously undocumented workings found by Bittenbender and others (1999). They extend for about a mile along the ridge that extends south and then east from the top of Lucky Chance Mountain. The site is plotted near the center of these workings which is about 0.5 mile northeast of the center of section 8, 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. he 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.
This site consists of several previously undocumented workings, four trenches and a 20-foot adit, found by Bittenbender and others (1999). The workings extend for about a mile along the ridge that extends south and then east from the top of Lucky Chance Mountain. They expose several quartz veins with rare pyrite and arsenopyrite, in phyllite and graywacke. The veins generally strike northwest and dip steeply to the northeast and southwest. Precious metal values in samples are generally low but two hand-selected samples contained 4,840 and 2,330 parts per billion gold.
Geologic map unit (-135.043652280895, 56.9443710433087)
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 Four undocumented trenches and a 20-adit were found during a study of the area by government geologists in the late 1990s.
Indication of production 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