Thetis

Prospects, Probably inactive

Commodities and mineralogy

Main commodities Au; Pb
Ore minerals galena; pyrite; pyrrhotite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale A-4
Latitude 57.0686
Longitude -135.2536
Nearby scientific data Find additional scientific data near this location
Location and accuracy There may be several old workings in the vicinity and the location used here is an adit that was found by Bittenbender and others (1999). The Thetis prospect is at an elevation of about 850 feet, about 0.7 mile north-northeast of Mount Verstovia in the NW1/4SW1/4 sec. 28, T. 55 S., R. 64 E. The prospect is location P-115 of Bittenbender and others (1999), location 55 of Cobb (1972, 1978), and MAS no. 0021140016 (U.S. Bureau of Land Management, 2002). The location is probably accurate but Cobb (1972, 1978) places it about a mile to the northeast based on a 1897 map by Becker that is probably more diagrammatic than precise.

Geologic setting

Geologic description

The Thesis prospect was located in 1888 (DeArmond 1997). By 1897, the prospect had been developed by two adits, a sawmill, and 2 prospecting mills (Becker, 1897). He described the deposit as a reticulated quartz vein 2 1/2 feet thick with calcite, pyrrhotite, and galena. A mill test of the ore indicated that it contained about $7 in gold (about 0.35 ounce of gold per ton) and $1 in silver. Becker described the host rock as schistose diorite. But modern mapping by Loney and others (1975) assign the rocks to the Jurassic and Triassic, Khaz Formation which consists of graywacke, greenschist, metachert, phyllite, and minor limestone; all cataclastically deformed. Bittenbender and others (1999) located and sampled a 30-foot adit here that cut a quartz vein less than a foot thick, and several thin quartz veinlets. The gold values in 4 samples were below the detection limit.
Geologic map unit (-135.255361624217, 57.0682379215682)
Mineral deposit model Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Triassic or younger based on the age of the host rock.

Production and reserves

Workings or exploration In 1898, the workings consists of two adits, a sawmill, and two prospecting mills. One 30-foot adit was located by Bittenbender and others (1999).
Indication of production None
Production notes Apparently none.

References

MRDS Number A013302

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.
DeArmond, R.N., 1997, Haleys and Silver Bay, in Around and About Alaska: Sitka Sentinel, series of 29 Articles, April to October, 1997.
U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
Reporters Donald Grybeck (U.S. Geological Survey)
Last report date 5/5/2005