Islander

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au; Zn
Other commodities As; Cd; Cu; Hg
Ore minerals pyrite; sphalerite
Gangue minerals carbonates

Geographic location

Quadrangle map, 1:250,000-scale SD
Quadrangle map, 1:63,360-scale B-5
Latitude 57.26686
Longitude -133.51074
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Islander prospect is on a small peninsula near the center of the head of Steamboat Bay; it is near the northwest corner of section 21, T. 53 S., R. 75 E.

Geologic setting

Geologic description

The Islander prospect was first staked in 1952 and there has been intermittent work on it since (Williams, 1952 [PE 115-04]). The deposit is in graywacke of Cretaceous or Jurassic age (Gehrels and Berg, 1992). The graywacke is cut by thin, discontinuous carbonate stringers that locally contain abundant pyrite and sphalerite. The stringers vary in strike from N55W to N85W and dip from 24 to 79S. The better gold values tend to be in the stringers with steeper dips. Williams (1952 [PE 115-04]) collected five samples of carbonate stringers 3 to 12 inches thick. They contained 0.16 to 0.48 ounce of gold per ton, and 1.19 to 7.5 percent zinc. One sample of a 11-foot-long veinlet collected by Still and others (2002) contained 7.352 parts per million (ppm) gold, more than 5 percent zinc, and anomalous copper, cadmium, and mercury. Another sample 19 feet long contained 1.077 ounces of gold per ton, 7 percent zinc, and more than 10,000 ppm arsenic.
There is a similar prospect about 0.5 mile northwest on the northeast side of Foot Island and another just to the south on the southeast shore of Steamboat Bay.
Geologic map unit (-133.512466852482, 57.2665164929812)
Mineral deposit model Carbonate veinlets in graywacke with gold and zinc.
Age of mineralization The auriferous carbonate veinlets are younger than the Jurassic to Cretaceous host rock.

Production and reserves

Workings or exploration Apparently only surface prospecting or small pits by private interests and sampling by government geologists.
Indication of production None

References

References

Bittenbender, P.E., Still, J.C., McDonald, M.E., Jr., and Gensler, E.C., 2000, Mineral investigations in the Stikine area, central Southeast Alaska: Bureau of Land Management, Alaska Open-File Report 83, 265 p., 2 sheets, scale, 1:250,000.
Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002 Mineral assessment of the Stikine area, central Southeast Alaska: U.S. Bureau of Land Management Technical Report 51, 560 p.
Reporters Donald Grybeck (U.S. Geological Survey)
Last report date 10/8/2004