Yakobi Island

The Yakobi Island 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: Yakobi Island
Secondary: Miner Island

Commodity

Primary: Gold
Secondary: Copper

Location

State: Alaska
District: Chichagof

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Model Name: Low-sulfide Au-quartz vein

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Clay gouge developed along shear zone.

Rocks

Name: Mafic Intrusive Rock
Role: Associated
Age Type: Associated Rock
Age Young: Late Cretaceous

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Gold
Gangue: Quartz

Comments

Comment (Geology): Age = Cretaceous or younger.

Comment (Production): Production Notes = About 55 ounces of gold were produced before 1917.

Comment (Commodity): Ore Material = Gold (native)

Comment (Workings): Workings / Exploration = A 35-foot-long adit was driven about 1887 on the shear zone, just above tide level. Four claims were active in 1917.

Comment (Geology): Geologic Description = The Yakobi Island gold-quartz vein is within an intrusion of quartz diorite, of Cretaceous age, which forms a major granitic batholith on Chichagof, Baranof, and Yakobi Islands (Loney and others, 1975). A coarse-grained hornblendite occurs within a few feet of the vein deposit. ? the mineralized quartz vein is from 1to 3 feet wide, dips steeply, and strikes northwest. The quartz occurs along a shear zone, associated with clay gouge, in a dark colored phase of the quartz diorite. Locally, the vein contains small amounts of chalcopyrite and native gold. The vein was developed by a short adit; the quartz pinched out in the adit, but was picked up on strike on the surface above the workings, indicating that quartz masses along the shear zone are lenticular (Overbeck, 1919).

Comment (Reference): Primary Reference = Overbeck, 1919

Comment (Commodity): Gangue = Clay (gouge)

Comment (Deposit): Other Comments = the site is in Rossman's hypothetical gold belt (plate 16, 1959). The site is in Tongass National Forest on land of unknown mining status.

Comment (Deposit): Model Name = Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).

References

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Mount Fairweather quadrangle, AK: U.S. Geological Survey Miscellaneous Field Study Map MF-436, 1 sheet, scale 1:250,000.

Reference (Deposit): Overbeck, R.M., 1919, Geology and mineral resources of the west coast of Chichagof Island: U.S. Geological Survey Bulletin 692, p. 91-136.

Reference (Deposit): Rossman, Darwin, 1959, Geology and ore deposits of the northwestern part of Chichagof Island, Alaska: U.S. Geological Survey Bulletin 1058-E, p. 139-216.

Reference (Deposit): Loney, R.A., Brew, D.A., Muffler, L.J. B., and Pomeroy, J.S., 1975, Reconnaissance geology of Chichagof, Baranof, and Kruzof Islands, southeastern Alaska: U.S. Geological Survey Professional Paper 792, 105 p.

Reference (Deposit): Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mt. Fairweather and Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-316, 123 p.

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