Inmachuk River

The Inmachuk River is a gold 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: Inmachuk River

Commodity

Primary: Gold
Secondary: Mercury

Location

State: Alaska
District: Fairhaven

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Model Name: Placer Au-PGE

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Cinnabar
Ore: Gold
Gangue: Hematite
Gangue: Pyrite

Comments

Comment (Reference): Primary Reference = Cobb, 1975 (OFR 75-429)

Comment (Workings): Workings / Exploration = The floodplain of Inmachuk River has been extensively placer mined, mostly by dredging (Cobb, 1975), over about 8.5 miles of length starting at an elevation of about 100 feet and continuing upstream to an elevation of about 250 feet.

Comment (Geology): Geologic Description = A significant part of the 578,000 ounces of gold and 32,000 ounces of silver recorded as produced from the Fairhaven district came from Inmachuk River (Hudson and DeYoung, 1978) . Its floodplain has been extensively placer mined, mostly by dredging (Cobb, 1975), over about 8.5 miles of length starting at an elevation of about 100 feet and continuing upstream to an elevation of about 250 feet. These elevations suggest that nearshore processes that accompanied Quaternary sea level fluctuations could have influenced the character of these deposits. The sides of Inmachuk River valley contain terrace gravels capped by basalt flows. Some of these gravels are gold-bearing (Moffit, 1927), and some Inmachuk River gold could have been reworked from them. However, early mining reported that the gold was little worn, some with quartz, and some in hematite pebbles (Moffit, 1905). Cinnabar pebbles up to 1/2 inch across were reported to be present in dredge concentrate by Anderson (1947). Most of the bedrock in the area is a metasedimentary schist and marble sequence of Lower Paleozoic age (Till and others, 1986).

Comment (Production): Production Notes = A significant part of the 578,000 ounces of gold and 32,000 ounces of silver recorded as produced from the Fairhaven district came from Inmachuk River (Hudson and De Young, 1978). The majority came from the Candle Creek area (BN074).

Comment (Geology): Age = Quaternary; two or more cycles of erosion and placer development occurred in the area.

Comment (Exploration): Status = Active?

Comment (Deposit): Model Name = Placer Au-PGE (Cox and Singer, 1986; model 39a)

References

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Bendeleben quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-417, 1 sheet, scale 1:250,000.

Reference (Deposit): Moffit, F.H., 1927, Mineral industry in Alaska in 1925: U.S. Geological Survey Bulletin 792-A, p. 1-39.

Reference (Deposit): Moffit, F.H., 1905, The Fairhaven gold placers, Seward Peninsula, Alaska: U.S. Geological Survey Bulletin 247, 85 p.

Reference (Deposit): Anderson, Eskil, 1947, Mineral occurrences other than gold deposits in northwestern Alaska: Alaska Territorial Division of Mines Pamphlet 5-R, 48 p.

Reference (Deposit): Till, A.B., Dumoulin, J.A., Gamble, B. ., Kaufman, D.S., and Carroll, P.I., 1986, Preliminary geologic map and fossil data, Soloman, Bendeleben, and southern Kotzebue quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 86-276, 10 p., 3 plates, scale 1:250,000.

Reference (Deposit): Hudson, T.L., and DeYoung, J. H., Jr., 1978, Map and tables describing areas of mineral resource potential, Seward Peninsula, Alaska: U.S. Geological Suvey Open-File Report 78-1-C, 62 p., one sheet, scale 1:1,000,000.

Reference (Deposit): Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Bendeleben quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-429, 123 p.

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