Gnat

The Gnat is a lead, copper, and molybdenum mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Gnat

Commodity

Primary: Lead
Primary: Copper
Primary: Molybdenum
Secondary: Gold

Location

State: Alaska
District: Ketchikan

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Polymetallic veins

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Galena
Ore: Molybdenite
Ore: Pyrite
Gangue: Albite
Gangue: Quartz

Comments

Comment (Workings): Workings / Exploration = The Gnat deposit was staked about 1900, when the vein probably was prospected chiefly for gold (Buddington, 1929, p. 120; Berg and Cobb, 1967, p. 182-183). Several channel and composite samples of the vein and of float probably derived from the vein assayed up to 1400 ppm Cu, 1500 ppm Pb, and 4700 ppm Mo (Berg and others, 1977, table 12).

Comment (Production): Production Notes = There is no record of any workings, or of any recovery of gold from the vein, but there probably was some small early production.

Comment (Deposit): Model Name = Polymetallic vein (Cox and Singer, 1986; model 22c)

Comment (Deposit): Other Comments = the site is in Misty Fiords National Monument Wilderness.

Comment (Reference): Primary Reference = Berg and others, 1977

Comment (Geology): Geologic Description = The country rocks in the area of the Gnat prospect is Tertiary or Cretaceous gneissic quartz diorite of the Coast Range batholith that locally contains inclusions of metasedimentary rocks (Berg and others, 1988). The quartz diorite near the prospect is cut by at least one two-foot-thick dike of altered felsic rock (Berg and others, 1977, p. 121).? the Gnat prospect consists of a glassy quartz-albite fissure vein 5.5 feet to 9.5 feet thick that strikes N20W and dips 59-80NE (Berg and Cobb, 1967, p. 182-183; Berg and others, 1977, p. 121). The vein is in gneissic quartz diorite and contains chalcopyrite, molybdenite, galena, and pyrite. The sulfides are relatively abundant for about 1.5 feet below the hanging wall; the rest of the vein is low in visible sulfides. Several channel and composite samples of the vein and of float probably derived from the vein assayed up to 1400 ppm Cu, 1500 ppm Pb, and 4700 ppm Mo (Berg and others, 1977, table 12). The Gnat deposit was staked about 1900, when the vein probably was prospected chiefly for gold (Buddington, 1929, p. 120 [B 807]; Berg and Cobb, 1967, p. 182-183). There is no record of any workings, or of any recovery of gold from the vein, but there probably was some small early production.

References

Reference (Deposit): Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

Reference (Deposit): Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Kimball, A. L., 1977, Mineral resources of the Granite Fiords wilderness study area, Alaska, with a section on aeromagnetic data by Andrew Griscom: U.S. Geological Survey Bulletin 1403, 151 p.

Reference (Deposit): Elliott, R.L., Berg, H.C., and Karl, Susan, 1978, map and table describing metalliferous and selected nonmetalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-file Report, 78-73-B,17 p., scale 1:250,000.

Reference (Deposit): Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map MF-1807,27 p., scale 1:250,000.

Reference (Deposit): Buddington, A.F., 1929, Geology of Hyder and vicinity, southeastern Alaska, with a reconnaissance of Chickamin River: U.S. Geological Survey Bulletin 807, 124 p.

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