Unnamed (near the north end of Shikosi Island)

The Unnamed (near the north end of Shikosi Island) is a silver, copper, and zinc 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 (near the north end of Shikosi Island)

Commodity

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

Location

State: Alaska
District: Juneau (Skagway subdistrict)

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: Epidotization, silicification.

Rocks

Role: Host
Age Type: Host Rock
Age Young: Late Triassic

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Gangue: Quartz
Gangue: Epidote

Comments

Comment (Geology): Age = the age of this occurrence is not well established, but can be no older than the Late Triassic age of the host rocks (Plafker, Hudson and Silberling, 1979; Plafker and Hudson, 1980). If the structure that localizes the mineralization is related to the Chatham Strait Fault, then the age of the mineralization is probably Tertiary or younger as most movement on the Chilkat Fault has been post-Mesozoic (Lanphere, 1978).

Comment (Geology): Geologic Description = Still and others (1991) describe this occurrence as, 'A narrow epidotized and silicified shear zone that contains chalcopyrite and chalcopyrite hosted in metabasalt.' Samples contained up to 0.05 ppm gold, 6.7 ppm silver, 3,000 ppm zinc, and 2.74% copper. This zone is similar to the unnamed occurrence (SK001) to the south on Kataguni Island. Plafker, Hudson, and Silberling (1979) and Plafker and Hudson (1980) note that on the Chilkat Peninsula the same metabasalts are vesicular and/or amygdaloidal and that well-developed pillow textures are locally present. Based in part on fossil evidence that supports a Late Triassic (Karnian) age, they suggest that the metavolcanics and carbonates may correlate with similar rocks of the Wrangellia terrane. The age of the mineralization is not well established, but can be no older than the Late Triassic age of the host rocks. If the structure that localizes the mineralization is related to the Chilkat Fault, then the age of the mineralization is probably Tertiary or younger as most movement on the Chilkat Fault has been post-Mesozoic (Lanphere, 1978).

Comment (Reference): Primary Reference = Still and others, 1991 (BOM, v. 2, sec. A)

Comment (Deposit): Model Name = Very little information. Base and precious metal mineralization localized along a shear zone in metabasalt.

Comment (Deposit): Other Comments = This occurrence is within the Chilkat Islands, State Marine Park.

Comment (Exploration): Status = Inactive

References

Reference (Deposit): Plafker George, Hudson, T.L., and Silberling, N.J., 1979, Upper Triassic fossils from a sequence of volcanic and sedimentary rocks on the Chilkat Peninsula, southeastern Alaska, in Johnson, K.M., and Williams, J.R., eds., The United States Geological Survey in Alaska: Accomplishments during 1978: U.S. Geological Survey Circular 804-B, p. B107-B110.

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.

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): Lanphere, M.A., 1978, Displacement history of the Denali fault system, Alaska and Canada: Canadian Journal of Earth Sciences, v. 115, p. 817-822

Reference (Deposit): Plafker, George, and Hudson, T., 1980, Regional implications of Upper Triassic metavolcanic and metasedimentary rocks on the Chilkat Peninsula, southeastern Alaska: Canadian Journal of Earth Sciences, v. 17, p. 681-689.

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