Unnamed (in saddle between Post River and South Fork)

The Unnamed (in saddle between Post River and South Fork) is a arsenic 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 (in saddle between Post River and South Fork)

Commodity

Primary: Arsenic
Secondary: Gold
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: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Polymetallic veins

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Secondary biotite (potassic) in the border phase.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Arsenopyrite
Gangue: Quartz

Comments

Comment (Exploration): Status = Inactive

Comment (Workings): Workings / Exploration = The reporter sampled the occurrence during a geologic mapping program for the Alaska Division of Geological and Geophysical Surveys in 1988 (Bundtzen, Harris, and Gilbert, 1997). One grab sample of the mineralized vein contained 6,500 ppm arsenic, 71 ppm gold, and 250 ppm antimony.

Comment (Geology): Geologic Description = This unnamed occurrence is a low-sulfide, quartz-carbonate vein or veins intruding a border phase of the 37.9 Ma, Hartman Pluton (Solie and others, 1991; Bundtzen, Harris, and Gilbert, 1997). The border phase consists of very fine-grained biotite-rich granodiorite and monzonite. The border phase is in contact with a massive hornfels aureole that is approximately 125 meters wide. A one meter wide, low sulfide, quartz carbonate vein swarm strikes N70W for about 115 meters through the saddle. The veins cuts the intrusive border phase, but apparently die out in the hornfels aureole. Disseminated arsenopyrite and pyrite grains occur near vein margins. One grab sample of the mineralized vein contained 6,500 ppm arsenic, 71 ppb gold, and 250 ppm antimony.

Comment (Deposit): Model Name = Polymetallic vein (Cox and Singer, 1986; model 22c).

Comment (Commodity): Gangue = Carbonate

Comment (Reference): Primary Reference = This description

References

Reference (Deposit): Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.

Reference (Deposit): Solie, D.N., Bundtzen, T.K., and Gilbert, W.G., 1991, K-Ar ages of igneous rocks in the McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File Report 160, 17 pages, one sheet, 1:250,000 scale.

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