Unnamed (on western edge of McBride Glacier)

Site Name

Primary: Unnamed (on western edge of McBride Glacier)

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Commodity

Primary: Gold
Primary: Copper
Secondary: Zinc
Secondary: Molybdenum
Secondary: Silver

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Location

State: Alaska
District: Juneau (Glacier Bay subdistrict)

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

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

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Physiography

Not available

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Mineral Deposit Model

Model Name: Polymetallic replacement
Model Name: Skarn Cu

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Copper, Iron Staining

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Rocks

Role: Host
Age Type: Host Rock
Age Young: Permian

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Analytical Data

Not available

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Materials

Ore: Arsenopyrite
Ore: Chalcopyrite
Ore: Pyrite
Ore: Pyrrhotite

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Comments

Comment (Geology): Age = Unknown. The Permian and Permian age of the metasedimentary host rocks establishes a maximum age, but the mineralization may be related to nearby Cretaceous or Tertiary granitic intrusives(Brew and others, 1978).

Comment (Geology): Age = Host rock is Permian.

Comment (Deposit): Model Number = 18b?, 19a?

Comment (Deposit): Other Comments = the occurrence is within Glacier Bay National Park and Preserve where mining and prospecting are restricted.

Comment (Exploration): Status = Inactive

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

Comment (Deposit): Model Name = This is only an occurrence with little available information . Based on the descriptions by Brew and others (1978) it appears to be a skarn or replacement occurrence (Cox and Singer, 1986; models 18b? or 19a?).

Comment (Workings): Workings / Exploration = Only sampling of outcrops.

Comment (Geology): Geologic Description = The following description is summarized from Brew and others (1978).?Arsenopyrite, chalcopyrite, pyrite, pyrrhotite, and traces of gold occur in ankeritic zones near an irregular, interfingered contact that marks a facies change between marble and phyllite. About 10 separate zones are present, each less than 10 feet wide and less than 100 feet long. The zones are copper and iron stained and are conformable to the bedding of the metasediments. One zone forms the hanging wall of 5-foot-wide andesite dike that contains chalcopyrite and pyrite. A 2-foot channel sample across an iron-stained zone in marble contained 0.003 ounce of gold per ton, 13,000 ppm copper, 200 ppm zinc, 15 ppm silver, 7,000 ppm arsenic, 5 ppm molybdenum, and more than 5,000 ppm manganese. Four other samples contained lesser amounts of metals. MacKevett (1971) reported a grab sample of sulfide-bearing rock that contained 0.088 ounce of gold per ton. The metasediments that host the deposit are Permian and Permian(?) in age which establishes a maximum age for the mineralization. Granitic intrusives in the general area are Cretaceous to Tertiary in age (Brew and others, 1978).

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References

Reference (Deposit): MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1967, Mineral resources of Glacier Bay National Monument, Alaska: U. S. Geological Survey Open-File Report 151, 176 p.

Reference (Deposit): Cobb, E.H., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska; Supplement to Open-File Report 78-316; Part B, Lists of references to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-B, 10 p.

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): Cobb, E.H., 1981, Summaries of data and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska, Supplement to Open-File Report 78-316, Part B in Lists of References to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-B, 10 p.

Reference (Deposit): Cobb, E.H., 1981, Summaries of data and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska, Supplement to Open-File Report 78-316, Part A in Summaries of data to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-A, 11 p.

Reference (Deposit): Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale approx. 1:600,000.

Reference (Deposit): Cobb, E.H., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska; Supplement to Open-File Report 78-316; Part A, Summaries of data to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-A, 11 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, 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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