Unnamed

The Unnamed is a copper and nickel 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

Commodity

Primary: Copper
Primary: Nickel
Secondary: Arsenic

Location

State: Alaska
District: Yentna

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Model Name: Skarn Cu

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Hydrothermally bleached conglomerate and local zones of tactite are described by C.C. Hawley and Associates, Inc. (1978).

Rocks

Name: Gabbro
Role: Associated
Age Type: Host Rock Unit
Age Young: Pennsylvanian

Name: Gabbro
Role: Associated
Age Type: Host Rock
Age Young: Pennsylvanian

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

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Pyrrhotite

Comments

Comment (Geology): Age = Late Cretaceous/early Tertiary; mineralization is interpreted to be linked to the Upper Yentna pluton, one of the Tertiary composite plutons mapped by Reed and Nelson (1980).

Comment (Commodity): Ore Material = nickel arsenide

Comment (Commodity): Ore Material = unknown platinoid

Comment (Deposit): Model Name = Cu skarn deposits (Cox and Singer, 1986; model 18b).

Comment (Reference): Primary Reference = Hawley, C.C.and Associates, Inc., 1978; Foley and others, 1997

Comment (Deposit): Other Comments = This site is located within Denali National Park and Preserve.

Comment (Workings): Workings / Exploration = Reconnaissance mapping, stream silt and rock sampling are all that have been done here. Rock samples contain up to 1,200 ppm copper, 10,000 ppm nickel, and greater than 10,000 ppm arsenic; nickel and chromium are reported to be anomalous in some samples associated with the gabbro phase of the intrusive (C.C. Hawley and Associates, Inc., 1978). Foley and others (1997) describe very- fine- grained pyrrhotite and chalcopyrite abundantly disseminated in the lamprophyric peridotite and alkali gabbro dikes of the Upper Yentna pluton. These contain up to 0.14% combined copper and nickel, 928 ppm arsenic, 125 ppb gold, 22 ppb platinum and 11 ppb palladium along the northeastern margin of the pluton.

Comment (Geology): Geologic Description = C.C. Hawley and Associates, Inc. (1978) shown this occurrence at the west end of the Dall tactite region. Mineralization is associated with the early Tertiary Upper Yentna pluton, which consists of syenite, monzonite, lamprophyric peridotite and alkali gabbro dikes, that cuts the Permian Conglomerate of Mt. Dall (Reed and Nelson, 1980; Foley and others, 1997). Two types of mineralization have been noted. C.C. Hawley and Associates, Inc. (1978) describe small pods of sulfides consisting of pyrite, chalcopyrite, and possibly nickel arsenide within local zones of tactite and hydrothermally bleached conglomerate. Rock samples contain up to 1,200 ppm copper, 10,000 ppm nickel, and greater than 10,000 ppm arsenic; nickel and chromium are reported to be anomalous in some samples associated with the gabbro phase of the intrusive (C.C. Hawley and Associates, Inc., 1978). Foley and others (1997) describe very- fine- grained pyrrhotite and chalcopyrite abundantly disseminated in the lamprophyric peridotite and alkali gabbro dikes of the Upper Yentna pluton. These contain up to 0.14% combined copper and nickel, 928 ppm arsenic, 125 ppb gold, 22 ppb platinum and 11 ppb palladium along the northeastern margin of the pluton.? the Upper Yentna pluton, one of the nine composite plutons (Tcp) described by Reed and Nelson (1980), sutures the fault contact between Mesozoic marine sedimentary rocks (KJs) and Paleozoic sedimentary rocks (Pzsu) (Reed and Nelson, 1980). Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from these plutons (Reed and others, 1978; Reed and Nelson, 1980; Nelson and others 1992). Gold and platinum group element placers have been worked at sites downstream from these bodies (Mertie, 1919; Cobb, 1973). Also see TL020, TL023, TL052, and TL053.

Comment (Exploration): Status = Inactive

References

Reference (Deposit): Foley, J.Y., Light, T.D., Nelson, S.W., and Harris, R.A., 1997, Mineral occurrences associated with mafic-ultramafic and related alkaline complexes in Alaska: Economic Geology, Monograph 9, p. 396-449.

Reference (Deposit): Fechner, S.A., Burleigh, R.E.., Foley, J.Y., and Lear, K.G., 1993, Results of the 1991-92 U.S. Bureau of Mines site-specific mineral investigations project in Alaska: U.S. Bureau of Mines Open-File Report 100-93, 127 p.

Reference (Deposit): Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.

Reference (Deposit): C.C. Hawley and Associates, Inc., 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U.S. Bureau of Mines Open-File Report 24-78, 275 p., 7 plates.

Reference (Deposit): Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, scale 1:250,000.

Reference (Deposit): Mertie, J.B., Jr., 1919, Platinum-bearing gold placers of the Kahiltna Valley: U.S. Geological Survey Bulletin 692-D, p. 233-264.

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