Unnamed (on headwater tributary to Porcupine Creek)

Site Name

Primary: Unnamed (on headwater tributary to Porcupine Creek)

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Commodity

Primary: Silver
Primary: Gold
Secondary: Copper

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Location

State: Alaska
District: Juneau (Skagway 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: Skarn Cu
Model Name: Skarn Zn-Pb

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Development of calc-silicate minerals.

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Pyrite

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Comments

Comment (Geology): Age = Probably Cretaceous or younger based on the age of the surrounding diorite (MacKevett and others, 1974).

Comment (Deposit): Model Name = Based on limited information, this is probably a skarn related occurrence (Cox and Singer, 1986; model 18b? or 18c?).

Comment (Geology): Geologic Description = According to Still and others (1991), this occurrence is a mineralized, 400 foot by 1,000 foot, roof pendant surrounded by diorite. The pendant consists of metamorphosed slate and limestone that form bands of garnet and diopside at some locations. Samples from the pendant contained up to 0.068 ppm gold, 1.1 ppm silver, 192 ppm zinc, and 230 ppm copper (Gilbert and others, 1991), and a sample of gossan rubble with 20% pyrite collected 500 feet below the pendant contained 6.33 ppm gold, 18.2 ppm silver, and 515 ppm copper (Still and others, 1991). The metamorphosed slate and limestone are of probable Paleozoic age (MacKevett and others, 1974). The bands of garnet and diopside and the mineralization are probably due to to contact metasomatism by the surrounding Cretaceous diorite (MacKevett and others, 1974).

Comment (Reference): Primary Reference = Still and others, 1991

Comment (Exploration): Status = Probably inactive

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References

Reference (Deposit): MacKevett, E.M., Jr., Robertson, E.C., and Winkler, G.R., 1974, Geology of the Skagway B-3 and B-4 quadrangles, southern Alaska: U.S. Geological Survey Professional Paper 832, 33 p.

Reference (Deposit): Gilbert, W.G., Still, J.C., Burns, L.E., Wier, K.R., and Redman, E.C., 1991, Geochemistry of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-5, 1 sheet, scale 1:63,360, 75 p.

Reference (Deposit): Still, J.C., Gilbert, W.G., and Forbes, R.B., 1987, Final report of stream sediment, float, and bedrock sampling in the Porcupine mining area, southeast Alaska, 1983-1985: U.S. Bureau of Mines Open-File Report 36-87, 35 p., 8 sheets.

Reference (Deposit): Gilbert, W.G., and Redman, E.C., 1989, Lode deposits, prospects, and occurrences of the Porcupine mining area, southeast Alaska: U.S. Bureau of Mines Open-File Report 17-89, 1 sheet, scale 1:39,600.

Reference (Deposit): Still, J.C., 1991, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984 - 1988, v. 2, Detailed mine, prospect, and mineral occurrence descriptions, section A, Haines-Klukwan-Porcupine subarea: U.S. Bureau of Mines of Mines Special Publication, 214 p.

Reference (Deposit): Still, J.C., Hoekzema, R.B., Bundtzen, T.K., Gilbert, W.G., Wier, K.R., Burns, L.E., and Fechner, S.A., 1991, Economic geology of Haines-Klukwan-Porcupine area, southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 91-4, 156 p., 5 sheets, scale 1:63,360.

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