Alder Gulch

The Alder Gulch is a silver and 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: Alder Gulch
Secondary: Vinasale

Commodity

Primary: Silver
Primary: Gold
Secondary: PGE
Secondary: Tungsten
Secondary: Bismuth
Secondary: Antimony

Location

State: Alaska
District: McGrath

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

Alteration Type: L
Alteration Text: Extensive oxidation of regolith results in grussification of plutonic suite.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Ilmenorutile
Ore: Scheelite
Ore: Monazite
Ore: Gold
Ore: Bismuth

Comments

Comment (Exploration): Status = Active

Comment (Geology): Geologic Description = The Alder Gulch heavy mineral placer deposit consists of auriferous, semi-residual and alluvial, unconsolidated deposits of Quaternary age in a steep gulch on the south flank of Vinasale Mountain. The placer deposit lies down slope and downstream from a mineralized 69.0 Ma granitic pluton that forms most of Vinasale Mountain (Bundtzen, 1986). Alder Gulch has only intermittent water flow and is dry through much of late summer and fall. ? the gold and heavy mineral bearing material ranges from 0.5 to 2 meters thick, over stream widths of 12 to 20 meters. Placer gold has been detected for about 2 kilometers below the main workings. The placer deposit begins just below the contact between quartz monzonite and sheared hornfels, which may be a mineralized source for the placer minerals. The stream gradient is very steep and averages about 100 meters/kilometer at the head of Alder Gulch. ? Principle heavy minerals identified during mining activities include placer gold that exhibits a fineness of 930, abundant native bismuth and scheelite; minor hastingsite, ilmenite, magnetite, and zircon; trace amounts of monazite, and ilmenorutile; and up to 2.6 ppm PGE (Bundtzen, 1986). The mineralogical source of the PGE is unknown. Sulfide-scheelite-quartz float found in the placer cut contains up to 14.3 grams/tonne gold (Bundtzen, 1986).

Comment (Geology): Age = Quaternary, based on geomorphic character (in active stream basin).

Comment (Deposit): Model Name = Gold heavy mineral placer (Cox and Singer, 1986; model 39a).

Comment (Deposit): Other Comments = Bundtzen (1986) collected a series of bulk concentrate samples from Peter Snow's 1982 operation, and concluded that up to 68 kilograms of scheelite could be recovered from one tonne of concentrate.

Comment (Production): Production Notes = Between 1930 and 1932, Carl Shutler mined in shallow hand mining cuts and produced 106.5 ounces (3.3 kg) gold and 20.2 ounces (0.6 kg) of byproduct silver Bundtzen, 1986). In 1981 and 1982, Peter Snow produced 16.5 ounces (503 grams) gold and 3.5 ounces (108 grams) of silver from a series of small test pits using a small tractor.

Comment (Workings): Workings / Exploration = Surface exploration includes samples collected and processed by mine operator Peter Snow and samples reported by Bundtzen (1986). Sulfide-scheelite-quartz float found in the mine cut contain up to 14.3 grams/tonne gold.

Comment (Reference): Primary Reference = Bundtzen, 1986

References

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

Reference (Deposit): Bundtzen, T.K., 1986, Prospect examination of a gold-tungsten placer deposit in Alder Creek, Vinasale Mountain area, western Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File Report 86-15, 10 pages.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.

Reference (Deposit): Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.

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