Unnamed (west of Anderson Mountain)

The Unnamed (west of Anderson Mountain) is a zinc, lead, copper, 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: Unnamed (west of Anderson Mountain)

Commodity

Primary: Zinc
Primary: Lead
Primary: Copper
Primary: Silver

Location

State: Alaska
District: Bonnifield

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: Massive sulfide, kuroko

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Absence of footwall alteration and stringer mineralization suggests off-vent deposition.

Rocks

Role: Host
Age Type: Host Rock
Age Young: Late Devonian

Analytical Data

Not available

Materials

Ore: Galena
Ore: Enargite
Ore: Chalcopyrite
Ore: Arsenopyrite
Ore: Sphalerite
Gangue: Sericite
Gangue: Siderite
Gangue: Barite
Gangue: Calcite
Gangue: Chlorite
Gangue: Quartz

Comments

Comment (Geology): Age = Mineralization was probably syngenetic with the Upper Devonian host rocks.

Comment (Reference): Primary Reference = Nokleberg and others, 1994

Comment (Exploration): Status = Active

Comment (Deposit): Other Comments = High geochemical values of arsenic, antimony, mercury, and tungsten may be derived from older schist basement. Anderson Mountain is significantly different from prospects in the Totatlanika Schist belt to the north (e.g. HE122) in having higher Cu content.

Comment (Geology): Geologic Description = The prospect is in the Upper Devonian(?) felsic metavolcanic schist and phyllite, often containing relict phenocrysts of quartz, orthoclase, and plagioclase (Wilson and others, 1998). The deposit consists of massive layers of chalcopyrite, galena, sphalerite, enargite, and arsenopyrite in gangue of quartz, sericite, chlorite, calcite, barite, and siderite. The sulfide beds appear to lie on an irregular paleosurface on the footwall, with domal sulfide accumulations at the tops of layers (Nokleberg and others, 1994). The Hines Creek fault, a major structure that is responsible for much structural complexity at Anderson Mountain, is two miles south of the prospect. Numerous high-angle faults displace the sulfide layers, and folding makes tracing the layers a challenge. The discovery drill hole in 1976 intersected a massive sulfide zone that measured 1.7 meters thick and assayed 1.2% copper, 2% lead, 8.5% zinc and 61.4 grams of silver per ton (Schuster, 1998). Surface grab samples reportedly contain 14% combined lead and zinc, 2.5% copper and 274 grams of silver per ton. Nokleberg and others (1994) report copper grades varying from 0.5 to 19%, lead grades up to 5%, up to 22% zinc and up to 170 grams of silver per ton.

Comment (Deposit): Model Name = Kuroko massive sulfide (Cox and Singer, 1986; model 28a)

Comment (Workings): Workings / Exploration = Geophysical and geochemical surveys have defined a potential zone of volcanogenic massive sulfide mineralization stretching over a strike length of 1373 meters. There has been about 2500 meters of drilling at the prospect (Robertson, 1998). The discovery drill hole in 1976 intersected a massive sulfide zone that measured 1.7 meters thick and assayed 1.2% copper, 2% lead, 8.5% zinc and 61.4 grams of silver per ton (Schuster, 1998). Surface grab samples reportedly contain 14% combined lead and zinc, 2.5% copper and 274 grams of silver per ton. Nokleberg and others (1994) report copper grades varying from 0.5 to 19%, lead grades up to 5%, up to 22% zinc and up to 170 grams of silver per ton.

References

Reference (Deposit): Schuster, T., 1998, Grayd advances Alaskan properties: The Northern Miner, v. 84, no. 18, p. 2.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

Reference (Deposit): Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 17 p., 2 sheetsm, scale 1:500,000.

Reference (Deposit): Robertson, R, 1998, Grayd hits massive sulphide: The Northern Miner, v. 84, no. 17, p. 3.

Reference (Deposit): Nokleberg, W.J., and others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America: The Geology of North America, v. G1, p. 855-904 and v. G1, Plate 11, scale 1:2,500,000.

Reference (Deposit): Cox, D.P., Light, T.D., Csejtey, Bela, Jr., and Campbell, D.L., 1989, Mineral resource assessment map of the Healy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map, MF-2058-A, scale 1:250,000.

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