Unnamed ('Sink Lake')

The Unnamed ('Sink Lake') is a lead, copper, gold, silver, 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 ('Sink Lake')

Commodity

Primary: Lead
Primary: Copper
Primary: Gold
Primary: Silver
Primary: Zinc

Location

State: Alaska
District: Ketchikan

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: Polymetallic veins

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Secondary copper and silver minerals suggest local supergene enrichment. Dolomitization of limestone; sericitization of rhyolitic volcanic rocks.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Magnetite
Ore: Pyrite
Ore: Pyrargyrite
Ore: Stibnite
Ore: Galena
Ore: Covellite
Ore: Chalcopyrite
Ore: Chalcocite
Ore: Barite
Ore: Tetrahedrite
Ore: Sphalerite
Gangue: Hematite
Gangue: Quartz
Gangue: Calcite

Comments

Comment (Geology): Age = Late Triassic or younger.

Comment (Workings): Workings / Exploration = Sheared rhyolite sampled in the 1970s by private interests reportedly contained massive chalcopyrite up to 2 inches thick, malachite coatings, and up to 50% magnetite (Karl, 1992). Karl's samples of sulfide- and/or magnetite-bearing quartz veins and country rocks at the sheared contact of greenstone and rhyolite contained up to 300 ppm Zn and 20 ppm Mo (Karl, 1992, loc. 35a, b). Other samples of sulfide-bearing quartz veins and of mineralized country rocks collected during USGS and private investigations in the 1930s, 1970s, and the early 1990s assayed as much as 0.03 oz. Au/ton, 20.4 oz. Ag/ ton, more than 2% Cu, 12.43 % Pb, more than 1% Zn, more than 1% Sb, 3000 ppm Ba, and 15 ppm Mo (Karl, 1992, loc. 35c).

Comment (Reference): Primary Reference = Karl, 1992

Comment (Geology): Geologic Description = The country rocks in the area of this site include undivided, metamorphosed Silurian and Ordovician volcanic, sedimentary, and intrusive rocks; and a sequence of recrystallized, Upper Triassic carbonate, clastic, and rhyolitic rocks that unconformably overlies the Paleozoic rocks (Berg, 1972). The rocks are complexly folded and faulted, and were metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.? the principal occurrence consists of sulfide-bearing quartz-calcite ladder and stringer veins in a 300-foot by 500-foot area at or near a faulted contact between dolomitic limestone and locally sericitized rhyolite (Karl, 1992, loc. 35c). The veins aggregate as much as 10% of the total rock volume in this area. A 10-foot-wide shear zone at the contact contains quartz veins that predate the shearing (Karl, 1992, loc. 35). The veins, which are mostly in the dolomitic limestone, contain galena, sphalerite, pyrite, hematite, tetrahedrite, stibnite, malachite, and barite. Samples collected in the 1930s by the USGS reportedly also contained chalcopyrite, covellite, chalcocite, and a trace of pyrargyrite ('ruby silver') (Berg, 1972, loc. 4). ? Sheared rhyolite sampled in the 1970s by private interests reportedly contained massive chalcopyrite up to 2 inches thick, malachite coatings, and up to 50% magnetite (Karl, 1992). Karl's samples of sulfide- and/or magnetite-bearing quartz veins and country rocks at the sheared contact of greenstone and rhyolite contained up to 300 ppm Zn and 20 ppm Mo (Karl, 1992, loc. 35a, b). Other samples of sulfide-bearing quartz veins and of mineralized country rocks collected during USGS and private investigations in the 1930s, 1970s, and the early 1990s assayed as much as 0.03 oz. Au/ton, 20.4 oz. Ag/ ton, more than 2% Cu, 12.43 % Pb, more than 1% Zn, more than 1% Sb, 3000 ppm Ba, and 15 ppm Mo (Karl, 1992, loc. 35c).

Comment (Deposit): Model Name = Polymetallic veins (Cox and Singer, 1986; model 22c)

References

Reference (Deposit): Elliott, R.L., Berg, H.C., and Karl, Susan, 1978, map and table describing metalliferous and selected nonmetalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-file Report, 78-73-B,17 p., scale 1:250,000.

Reference (Deposit): Karl, S.M., 1992, Map and table of mineral deposits on Annette Island, Alaska: U.S. Geological Survey Open-File Report 92-690, 57 p., 1 map, scale 1:63,360.

Reference (Deposit): Berg, H.C., 1972, Geologic map of Annette Island, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-684, 8 p., 1 sheet, scale 1:63,360,

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