|Quadrangle map, 1:250,000-scale||SI|
|Quadrangle map, 1:63,360-scale||A-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Gangola prospect is at an elevation of about 200 feet on the east side of Silver Bay, about midway between Herring Cove and Bear Cove. The prospect is 0.5 mile west of the center of sec. 12, T. 56 S., R. 64 E. It is location P-118 of Bittenbender and others (1999) and MAS no. 0021140160 (U.S. Bureau of Land Management, 2002). The location is accurate.|
Geologic descriptionThe rocks in the vicinity of this prospect are part of the Jurassic and Triassic, Khaz Formation which consists of of graywacke, greenschist, metachert, phyllite, and minor limestone (Loney and others, 1975). A prospector located a claim here in 1970 and dug several trenches. The deposit consists of three quartz veins up to 1.5 feet thick that are exposed for up to 15 feet; they strike N35-70E and dip steeply (U.S. Bureau of Mines, 1973) . The veins contain scheelite, chalcopyrite and pyrrhotite (Bittenbender and others, 1999). The best sample of a vein was a 1.5-foot-long sample in a small cut that contained 80 parts per billion (ppb) gold, 375 parts per million (ppm) copper, and 380 ppm tungsten. A sample of sulfide-bearing greenstone on the side of a vein contained 570 ppm gold, 960 ppm copper, and 1,100 ppm tungsten. A hand-picked sample from a dump contained 85 ppb gold, 260 ppm copper, and 760 ppm tungsten.
|Geologic map unit||(-135.179363304144, 57.0270373987783)|
|Mineral deposit model||Quartz vein with scheelite and chalcopyrite.|
|Age of mineralization||Triassic or younger based on the age of the host rocks.|
|Workings or exploration||Several short trenches on quartz veins.|
|Indication of production||None|
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.
Loney, R.A., Brew, D.A., Muffler, L.J.P., and Pomeroy, J.S., 1975, Reconnaissance geology of Chichagof, Baranof, and Kruzof Islands, southeastern Alaska: U.S. Geological Survey Professional Paper 792, 105 p.
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]
U.S. Bureau of Mines, 1973, Alaska 1:250,000-scale quadrangle map overlays showing mineral deposit locations, principal minerals, and number and type of claims: U.S. Bureau of Mines Open-File Report 20-73, 95 overlays (updated in 1986, 1987).
|Reporters||Donald Grybeck (U.S. Geological Survey)|
|Last report date||5/5/2005|