Unnamed (near Sylburn Harbor)

The Unnamed (near Sylburn Harbor) is a barium-barite, silver, zinc, and lead 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 Sylburn Harbor)

Commodity

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

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: The rocks locally are sericitized, silicified, dolomitized, and permeated with hydrothermal hematite.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Sphalerite
Ore: Galena
Ore: Barite
Gangue: Calcite

Comments

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

Comment (Reference): Primary Reference = Karl, 1992

Comment (Workings): Workings / Exploration = Samples of brecciated dolomite, massive dolomite, and sheared metabasite with calcite veins contained up to 100 ppm Pb, 300 ppm Zn, and 500 ppm Ba; a sample of barite contained 7 ppm Ag and 7000 ppm Zn; a sample of silicified tuff contained 1.5 ppm Ag, 1000 ppm Pb, 1500 ppm Zn, and 150 ppm Cr; samples of volcanic agglomerate with calcite veins, and of mylonitic calcareous conglomerate, contained up to 200 ppm Pb and 700 ppm Zn; and samples of pyritic rhyolite tuff-breccia and pyritic gray limestone contained up to 150 ppm Pb and 300 ppm Zn (Karl, 1992, loc. 21a-f). A mapping and soil survey by private interests in the 1970s indicated that the barite-rich zone extends for about 210 feet along the west shore of a small peninsula, and for about 400 feet inland from there (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 are 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; Berg and others, 1988; Karl, 1992). The rocks are folded and locally intensely sheared, sericitized, silicified, dolomitized, and permeated with hydrothermal hematite. The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The occurrences consist of up to 3-foot-thick pods of barite in dolomite, and of barite-calcite fissure veins in sheared and brecciated rhyolite (Berg, 1972, loc. 17; Karl, 1992, loc. 21a-f). The dolomite and rhyolite contain galena and sphalerite; the barite contains argentiferous galena and sphalerite. The barite in the pods occurs as radial blades, with rosettes of barite up to 20 inches in diameter. . Samples of brecciated dolomite, massive dolomite, and sheared metabasite with calcite veins contained up to 100 ppm Pb, 300 ppm Zn, and 500 ppm Ba; a sample of barite contained 7 ppm Ag and 7000 ppm Zn; a sample of silicified tuff contained 1.5 ppm Ag, 1000 ppm Pb, 1500 ppm Zn, and 150 ppm Cr; samples of volcanic agglomerate with calcite veins, and of mylonitic calcareous conglomerate, contained up to 200 ppm Pb and 700 ppm Zn; and samples of pyritic rhyolite tuff-breccia and pyritic gray limestone contained up to 150 ppm Pb and 300 ppm Zn (Karl, 1992, loc. 21a-f). A mapping and soil survey by private interests in the 1970s indicated that the barite-rich zone extends for about 210 feet along the west shore of a small peninsula, and for about 400 feet inland from there (Karl, 1992).

References

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,

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.

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