Goldwin

Mine, Undetermined

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale D-8
Latitude 57.9936
Longitude -136.3359
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Goldwin Mine is on northwestern Chichagof Island, near the tip of the point at the junction of Lisianski Strait and Lisianski Inlet. The mine is at an elevation of about 350 feet, about 0.6 mile southeast of the center of sec. 4, T. 45 S., R. 56 E. It is location P-13 of Bittenbender and others (1999), location 3 of Cobb (1972, 1978), and MAS. no. 0021140039 (U.S. Bureau of Land Management, 2002). The location is accurate.

Geologic setting

Geologic description

The Goldwin deposit consists of auriferous, sulfide-bearing quartz veins along faults in Cretaceous or Jurassic diorite (Rossman, 1959; Johnson and Karl, 1985; Bittenbender and others, 1999). The veins pinch and swell, range in thickness from less than an inch to about 2.5 feet, and have been traced in surface and underground workings for about 400 feet. The quartz contains sparse pyrite and chalcopyrite, mainly near altered diorite inclusions in the veins. The gold is free-milling and mainly accompanies the sulfides; the altered wallrock also carries a little gold.
The deposit was located in 1920 and probably was mined intermittently until WW II. Workings included pits, trenches, and an adit about 250 feet long. An unknown, but probably small, amount of gold and silver were recovered. Picked samples reportedly assayed about 1.7 ounces of gold per ton (Reed and Coats, 1941) and 2.9 ounces of gold per ton (Buddington, 1925); Rossman (1959) reported an assay of 69 ounces of gold per ton over a half-foot section of pyrite-rich vein. Kimball (1982) collected representative samples that assayed up to 0.11 ounce of gold per ton.
Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
Geologic map unit (-136.33773596361, 57.993216708572)
Mineral deposit model Low sulfide, gold-quartz veins (Cox and Singer, 1986, model 36a).
Mineral deposit model number 36a
Age of mineralization Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
Alteration of deposit Unspecified hydrothermal(?) alteration of diorite wallrock in and adjacent to the veins.

Production and reserves

Workings or exploration The deposit was located in 1920 and probably was mined intermittently until WW II. Workings included pits, trenches, and an adit about 250 feet long.
Indication of production Yes; small
Production notes The deposit was intermittently mined from 1920 to 1941 but there are no records of the amount of production.

References

MRDS Number AO13239

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.
Goldfarb, R J., 1997, Metallogenic evolution of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 4-34.
Haeussler, P J., Bradley, D., Goldfarb, R., Snee, L., and Taylor, C., 1995, Link between ridge subduction and gold mineralization in southern Alaska: Geology, v. 23, no. 11, p. 995-998.
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 H.C. Berg (U.S. Geological Survey)
Last report date 10/16/2004