The Unnamed is a copper, gold, 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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Unnamed MRDS details
Site Name
Primary: Unnamed
Commodity
Primary: Copper
Primary: Gold
Primary: Silver
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: Development of calc-silicate mineral assemblages in tactitized limestone, and silicification of argillite and siltstone (C.C. Hawley and Associates, Inc., 1978).
Rocks
Name: Diorite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Pliocene
Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene
Analytical Data
Not available
Materials
Ore: Bornite
Ore: Chalcopyrite
Ore: Gold
Gangue: Calcite
Gangue: Diopside
Gangue: Garnet
Gangue: Wollastonite
Comments
Comment (Commodity): Ore Material = unknown platinoid
Comment (Commodity): Ore Material = unknown silver mineral
Comment (Exploration): Status = Inactive
Comment (Geology): Age = Late Cretaceous/early Tertiary; mineralization is interpreted to be linked to the Cascade pluton dated as 64.6 +/- 1.8 m.y. by K/Ar methods (Reed and Lanphere, 1972).
Comment (Reference): Primary Reference = C.C. Hawley and Associates, Inc., 1978
Comment (Workings): Workings / Exploration = Reconnaissance mapping, prospecting, stream silt, pan concentrate and rock sampling are all that have been done here. Foley and others (1997) report mean values of 20 ppb gold, 1 ppb palladium, 42 ppb platinum, 139 ppm nickel, and 26 ppm copper from six rock samples of the Cascade pluton. Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from the composite plutons mapped by Reed and Nelson (1980) in the southern Alaska Range (Reed and others, 1978; Nelson and others 1992). Gold and platinum group element placers have been worked at sites downstream from these bodies (Mertie, 1919; Cobb, 1973).
Comment (Deposit): Model Name = Cu skarn deposits (Cox and Singer, 1986; model 18b).
Comment (Geology): Geologic Description = At this occurrence massive Middle or Upper Devonian limestone (Dl), Paleozoic siliceous black argillite, and minor siltstone (Pzus) are intruded by the Cascade pluton, a 64.6 m.y. old composite pluton (Tcp) which consists of granite-porphyry, intermediate phase rocks and lamprophyre (Reed and Nelson, 1980). The mineral occurrence is separated from the intrusion by a few feet of pyritic, silicified black argillite. Massive bornite and chalcopyrite occur in a replacement band 0.3 to 3 feet wide, with free gold in thin calcite-diopside seams within banded tactite. One sample contained 25% copper, 41 oz/ton silver and 0.7 oz/ton gold over a three foot width (C.C. Hawley and Associates, Inc., 1978). Foley and others (1997) report locally abundant bornite within the pluton and anomalous gold in the lamprophyre (31 ppb) and in granite-porphyry (88 ppb). They also note anomalous platinum (300 ppb) in pan concentrate samples at the eastern margin of the pluton. The pluton has converted the country rocks to a tactite assemblage which includes diopside and wollastonite.? This occurrence is part of 10-mile-long tactite zone related to Cascade pluton; another anomalous area lies about three quarters of a mile southwest of this site (TL066) where bleached tactite zone in pebble conglomerate and extends for hundreds of yards between Cascade pluton and a small outlying stock.? the Cascade pluton has a composition similar to the Kohlsaat pluton (Reed and Nelson, 1980; Nelson and others, 1992). Foley and others (1997) report mean values of 20 ppb gold, 1 ppb palladium, 42 ppb platinum, 139 ppm nickel, and 26 ppm copper from six rock samples of the Cascade pluton. Anomalous gold, platinum-group elements, copper, chrome, nickel and arsenic are reported from the composite plutons mapped by Reed and Nelson (1980) in the southern Alaska Range (Reed and others, 1978; Nelson and others 1992). Gold and platinum group element placers have been worked at sites downstream from these bodies (Mertie, 1919; Cobb, 1973). See also TL020, TL023, TL052, and TL053.
Comment (Deposit): Other Comments = the Cascade pluton has also been called the Dall Stock (C.C. Hawley and Associates, 1978). This occurrence is part of a 10-mile-long tactite zone related to Cascade pluton; another anomalous area lies 1 mile southwest of this site: bleached tactite zone in Dall Limestone pebble conglomerate extends for hundreds of yards between Cascade pluton and small outlying stock. This site is located within Denali National Park and Preserve.
Comment (Commodity): Ore Material = unknown silver mineral
Comment (Commodity): Ore Material = unknown platinoid
References
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.
Reference (Deposit): MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Reference (Deposit): Nelson, S.W., Foley, J.Y., and Nelson, B.K., 1992, Metal-rich lamprophyric and associated alkaline mafic, ultramafic and intermediate to felsic rocks from composite plutons, central Alaska Range, Alaska [abs.]: International Conference on Arctic Margins, Anchorage, Alaska, September 2-4, 1992, Abstracts with Program.
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): Cobb, E.H., and Reed, B.L., 1980, Summaries of data and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p.
Reference (Deposit): Reed, B.L., and Lanphere, M.A., 1972, Generalized geologic map of the Alaska-Aleutian range batholith showing potassium-argon ages of the plutonic rocks: U.S. Geological Survey Miscellaneous Field Studies Map MF-372, 2 sheets, scale 1:1,000,000.
Reference (Deposit): Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.
Reference (Deposit): Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.
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.
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