Unnamed (near Hemlock Bay)

The Unnamed (near Hemlock Bay) is a barium-barite, silver, zinc, lead, and copper 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 Hemlock Bay)

Commodity

Primary: Barium-Barite
Primary: Silver
Primary: Zinc
Primary: Lead
Primary: Copper

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: Country rocks locally are sericitized and permeated with hydrothermal hematite.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Sphalerite
Ore: Pyrite
Ore: Galena
Ore: Barite
Gangue: Quartz
Gangue: Calcite

Comments

Comment (Geology): Age = Fissure veins probably are Late Cretaceous or younger.

Comment (Reference): Primary Reference = Karl, 1992

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

Comment (Geology): Geologic Description = The country rocks in the area of this site include recrystallized, Upper Triassic carbonate and clastic rocks, rhyolite, and basalt; Silurian trondhjemite; and greenstone derived from undivided Silurian and Ordovician volcanic, sedimentary, and intrusive rocks (Berg, 1972 [I 684]; Berg and others, 1988; Karl, 1992). The rocks are folded and locally intensely sheared, sericitized, and permeated with hydrothermal hematite. The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The occurrences consist of quartz-barite-sulfide fissure veins in cataclastic to mylonitic Paleozoic greenstone, carbonate, and trondhjemite; locally, they are in Triassic limestone and rhyolite that generally are in fault contact with the Paleozoic rocks (Karl, 1992, loc. 24). Pyrite and hematite are reported at some of the occurrences; sulfide minerals, inferred from sample analyses, probably are mainly galena and sphalerite. . Variously mineralized samples of greenstone and other country rocks, barite-bearing veins, and quartz-sulfide veins contained up to 2 ppm Ag, 700 ppm Cu, 100 ppm Pb, 700 ppm Zn, more than 5000 ppm Ba, 500 ppm Cr, and 200 ppm Ni; soil and rock samples collected in the 1970s by private interests contained up to 475 ppm Cu and 1100 ppm Zn (Karl, 1992, loc. 24a-f).

Comment (Workings): Workings / Exploration = Variously mineralized samples of greenstone and other country rocks, barite-bearing veins, and quartz-sulfide veins contained up to 2 ppm Ag, 700 ppm Cu, 100 ppm Pb, 700 ppm Zn, more than 5000 ppm Ba, 500 ppm Cr, and 200 ppm Ni; soil and rock samples collected in the 1970s by private interests contained up to 475 ppm Cu and 1100 ppm Zn (Karl, 1992, loc. 24a-f).

References

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., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map MF-1807,27 p., scale 1:250,000.

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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