Unnamed (on Idaho Ridge)

The Unnamed (on Idaho Ridge) is a molybdenum and tungsten 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 (on Idaho Ridge)

Commodity

Primary: Molybdenum
Primary: Tungsten
Secondary: Silver
Secondary: Copper

Location

State: Alaska
District: Juneau

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

Not available

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Epidote along quartz veins.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Scheelite
Ore: Molybdenite
Ore: Chalcopyrite
Gangue: Quartz

Comments

Comment (Exploration): Status = Inactive

Comment (Reference): Primary Reference = Kimball and others, 1978

Comment (Deposit): Model Name = Low-grade porphyry molybdenum-tungsten deposit.

Comment (Workings): Workings / Exploration = No workings A sample of mineralized float (USGS No. 75CN108A--Brew and others, 1978, table B-8) contained 700 ppm molybdenum, 300 ppm tungsten, 100 ppm Bi, and 10 ppm silver. In 1976, the U.S. Bureau of Mines found thin quartz-sulfide veinlets at two locations on Idaho Ridge that contained as much as 500 ppm tungsten, 300 ppm molybdenum, 15 ppm silver, and 240 ppm copper (Kimball and others, 1978, p. C310-312). The Bureau suggested that prospecting around the margins of the host intrusive could reveal better mineralized zones.

Comment (Geology): Geologic Description = The Idaho Ridge area is underlain mostly by foliated granitic rock of Cretaceous age, covered locally by deep glacial moraine (MacKevett and others, 1971; Brew and others, 1978). At the site investigated by the U.S. Bureau of Mines widely distributed fractures in granitic rock had propylitic alteration (epidote); the intrusive was also cut by unmineralized breccia zones (Kimball and others, 1978; p. C310-312). A float rock sample (75CN108A) collected near this area by the U.S. Geological Survey in 1975 contained 700 ppm molybdenum, 300 ppm tungsten, 100 ppm bismuth, and 10 ppm silver (Brew and others, 1978, table B-8). In follow-up activity conducted by the U.S. Bureau of Mines in 1976, significant mineralization was found in narrow (to 0.15 foot) quartz-sulfide veins, but not in chip samples collected over a 5 to 13 foot width (Kimball and others, 1978, table C56): Selected samples of thin quartz-sulfide veinlets contained as much as 240 ppm copper, 500 ppm tungsten, 300 ppm molybdenum, and 15 ppm silver.

Comment (Deposit): Other Comments = Veins found to date are too thin to be of economic interest, but anomalous geochemical samples suggest more prospecting of the area would be justified (Kimball and others, 1978, p. C310-312, including fig. C65). The site is in Glacier Bay National Park and Preserve.

Comment (Geology): Ore Material = 'sulfides'

Comment (Geology): Age = Cretaceous or younger. Veins post-date foliated granitic intrusion of Cretaceous age.

References

Reference (Deposit): MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.

Reference (Deposit): Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources, in Brew, D. A., and others, Mineral resources of the Glacier Bay National Monument wilderness study area, Alaska: U.S. Geological Survey Open-File Report 78-494, p. C1-C375.

Reference (Deposit): Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p.

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