The Unnamed (southwest Gilbert Peninsula) is a copper and molybdenum 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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Unnamed (southwest Gilbert Peninsula) MRDS details
Site Name
Primary: Unnamed (southwest Gilbert Peninsula)
Commodity
Primary: Copper
Primary: Molybdenum
Secondary: Zinc
Secondary: Bismuth
Secondary: Silver
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
Model Name: Porphyry Cu-Mo
Orebody
Not available
Structure
Not available
Alterations
Alteration Type: L
Alteration Text: Silicification in stockwork zones.
Rocks
Not available
Analytical Data
Not available
Materials
Ore: Chalcopyrite
Ore: Molybdenite
Ore: Pyrite
Ore: Sphalerite
Gangue: Quartz
Comments
Comment (Deposit): Model Name = Porphyry copper-molybdenum (Cox and Singer, 1986; model 21a).
Comment (Geology): Geologic Description = Southern Gilbert Peninsula and nearby areas are mainly underlain by granitic rock of Cretceous age containing local inliers of metamorphosed hornfels and marble of Paleozoic age (Brew and others, 1978). On the southwest tip of Gilbert Peninsula,stockworks of quartz veins in altered quartz diorite--cut by light colored aplite (alaskitic) dikes--occur in a silicified zone at least 50 feet wide and several hundred feet long. The quartz veins contain minor amounts of chalcopyrite and molybdenite close to vein selvages. The mineralogy and intrusive setting suggests a porphyry copper-molybdenum model. Pyritic stockworks and somewhat younger crosscutting pyritic veins also occur to the east across Hugh Miller Inlet and west across Scidmore Inlet. Selected vein samples from location 45 contained as much as 10 ppm silver, 7000 ppm copper and 2000 ppm molybdenum (MacKevett and others, 1971); chip samples collected across 52- and 100-foot long lines were nearly barren. Samples collected in pyritic stockwork vein areas on the west side of Scidmore Inlet contained a trace of molybdenum and as much as 70 ppm bismuth, and 1500 ppm zinc (Kimball and others, 1978, location 55).
Comment (Geology): Age = Tertiary.
Comment (Exploration): Status = Inactive
Comment (Commodity): Gangue = alteration products of quartz diorite
Comment (Commodity): Gangue = alaskite
Comment (Deposit): Other Comments = Fairly large but very low grade quartz vein and stockwork system. It is in Glacier Bay National Park and Preserve.
Comment (Reference): Primary Reference = MacKevett and others, 1971
Comment (Workings): Workings / Exploration = The mineralized area was described briefly by Rossman (1963, B 1121-K) and investigated in 1966 in conjunction with the Geological Survey's study of Glacier Bay (MacKevett and others, 1971). There are no mine workings. A 0.5 foot quartz vein collected on the southwest tip of Gilbert Peninsula contained 1000 ppm copper; a selected high-grade piece of quartz float contained 10 ppm silver, 7000 ppm copper and 2000 ppm molybdenum (MacKevett and others, 1971, p. 50-51, table 9). To the west, across Scidmore Inlet, a selected sample contained 1500 ppm zinc and 70 ppb bismuth. The average grade of exposed materials is very low, as long chip samples contained only near background amounts of valuable metals.
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): Rossman, Darwin, 1963, Geology of the eastern part of the Mount Fairweather quadrangle, Glacier Bay, Alaska: U.S. Geological Survey Bulletin 1121-K, p. K1-K57.
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): 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): 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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