Gemini

The Gemini is a tin and silver 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: Gemini
Secondary: South Vein

Commodity

Primary: Tin
Primary: Silver
Secondary: Iron
Secondary: Arsenic
Secondary: Copper
Secondary: Lead
Secondary: Antimony
Secondary: Tungsten
Secondary: Zinc

Location

State: Alaska
District: Innoko

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: Sn-polymetallic vein

Orebody

Not available

Structure

Not available

Alterations

Alteration Text: Axinite-sericite-tourmaline replacements.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Arsenopyrite
Ore: Cassiterite
Ore: Chalcopyrite
Ore: Sphalerite
Gangue: Axinite
Gangue: Quartz
Gangue: Tourmaline

Comments

Comment (Reference): Primary Reference = Burleigh, 1992 (BMOFR 85-92)

Comment (Workings): Workings / Exploration = A data release from the U.S. Geological Survey AMRAP survey of the Medfra quadrangle (King and others, 1980; Patton and others, 1980) indicated that anomalous tin, tungsten, bismuth, lead, silver, and arsenic were detected in stream sediment and pan concentrate samples draining the Gemini prospect area. Duval Corporation and Anaconda Minerals Company followed up on this work and discovered the Gemini and related vein systems. In 1984, Anaconda Minerals Company completed three shallow diamond drill holes into the Gemini and South Veins. The Anaconda Minerals Company drill program encountered up to 8.15 percent tin and 3.91 ounces/ton silver over widths of 1.5 feet (0.45 m). Online Exploration Services Inc. (Anchorage, Alaska) explored the property in 1997.

Comment (Geology): Geologic Description = The Gemini prospect consists of three, closely spaced, North 65 degree West-trending breccia veins that cut thermally altered Upper Cretaceous, Kuskokwim Group flysch. The vein deposits consist of crackle breccias and limonitic brecciated hornfels that contain massive to disseminated cassiterite, arsenopyrite, chalcopyrite, and sphalerite. Cassiterite-bearing veins can be traced east of the ridge summit, but not to the west. The Gemini Vein has a minimum strike length of 900 feet (275 m), whereas the South Vein could be traced for about 4,300 feet (1,310 m). The Gemini prospect is inferred to be Late Cretaceous-Early Tertiary age, based on radiometric ages of related pluronic rocks in Kuskokwim Mineral Belt (Bundtzen and Miller, 1997). A 1984 Anaconda Minerals Company drill program encountered up to 8.15 percent tin and 3.91 ounces/ton silver over widths of 1.5 feet (0.45 m) in the Gemini vein.

Comment (Geology): Age = Late Cretaceous-Early Tertiary age, based on radiometric ages of related plutonic rocks in Kuskokwim Mineral Belt (Bundtzen and Miller, 1997).

Comment (Deposit): Model Name = Tin-polymetallic deposits (Cox and Singer, 1986; model no. 20b)

Comment (Reserve-Resource): Reserves = Based on Anaconda Minerals Company exploration data and their own surface sampling, Burleigh (1992 BMOFR 85-92) and Bundtzen and Miller (1997) estimate that 1,153,333 tons (1,046,300 tonnes) of ore contains 0.216 percent tin. The average tenor for other metals (silver, arsenic, lead, tungsten, antimony, and zinc) was not calculated.

Comment (Deposit): Other Comments = See Won - South (MD024), Win (MD060), Won - North (MD021) and Cloud (MD059) prospects.

Comment (Exploration): Status = Active

References

Reference (Deposit): Burleigh, R.E., 1992, Tin mineralization at the Won prospect, west-central Alaska: U.S. Bureau of Mines Open-File Report 85-92, 19 pages.

Reference (Deposit): Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Economic Geology Monograph #9, Mineral Deposits of Alaska, p. 242-286.

Reference (Deposit): King, H.D., Risoli, D.A., Cooley, E.F., O'Leary, R.M., Speckman, W.A., Speisman, D.L., and Galland, D.W., 1980, Final results and statistical summary of analyses of geochemical samples from the Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811F, 134 pages.

Reference (Deposit): Patton, W.W., Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L., and Chapman, R.M., 1980, Preliminary geologic map of Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811-A, 1 sheet, scale l:250,000.

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