Sweeny

Prospect, Active

Alternative names

Comet City

Commodities and mineralogy

Main commodities Au
Other commodities Pb
Ore minerals pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale D-4
Latitude 58.8541
Longitude -135.1276
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Sweeny prospect is at an elevation of about 350 feet, about 1 mile east of Pt. Sherman on Lynn Canal and 3 miles southwest of Lions Head Mountain in the Kakuhan Range. It is in the Sherman Creek drainage in the NE1/4 section 7, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The Sweeny prospect, originally called the Comet City mine, was developed in 1904 by T.H. Jarmey, who completed 2 adits, estimated to be 20 feet and 100 feet long, by 1905. The deposit is in black phyllite and consists of several thin concordant, discontinuous quartz veins that carry minor amounts of pyrrhotite. U.S. Bureau of Mines samples contained elevated lead values but no gold (Redman and others, 1989).
The Sweeny prospect is in the Berners Bay district at the north end of the Juneau Gold Belt. The district is characterized by a series of structurally-controlled, mesothermal, gold-bearing quartz veins. Most of the veins are in Early Cretaceous (105 Ma) Jualin Diorite, which intrudes Mesozoic (Upper Triassic) metabasalt (Miller and others, 1995). The age of mineralization in the Berners Bay district is about 55 Ma, the same as the other mesothermal gold vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).
Geologic map unit (-135.129423048015, 58.8537685542971)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization The age of mineralization in the Berners Bay district is about 55 Ma, the same as the other mesothermal gold-quartz-vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).

Production and reserves

Workings or exploration The Sweeny prospect, originally called the Comet City mine, was developed in 1904 by T.H. Jarmey, who completed 2 adits, estimated to be 20 feet and 100 feet long, by 1905. This prospect is currently (2001) under control of Coeur Alaska.
Indication of production None

References

References

Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Miller, L.D., Goldfarb, R.J., Snee, L.W., Gent, C.A., and Kirkham, R.A., 1995, Structural geology, age, and mechanisms of gold vein formation at the Kensington and Jualin deposits, Berners Bay district, southeast Alaska: Economic Geology, v. 90, p. 343-368.
Reporters J.C. Barnett and L.D. Miller (Juneau, Alaska )
Last report date 12/15/2001