Unnamed (near Sylburn Harbor)

Occurrence in Alaska, United States with commodities Silver, Barium-Barite, Lead, Zinc

Geologic information

Identification information

Deposit ID 10307685
Record type Site
Current site name Unnamed (near Sylburn Harbor)

Geographic coordinates

Geographic coordinates: -131.57576, 55.17374 (WGS84)
Relative position This site represents six occurrences near the north base of the peninsula between Sylburn Harbor and Port Chester. The occurrences are in sections 20 and 21, T. 77 S., R. 92 E., of the Copper River Meridian. The map site is at the approximate center of this group of occurrences. The site corresponds to loc. 20a-f in Karl (1992). The location is accurate within about 0.15 mile.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Barium-Barite Primary
Lead Primary
Zinc Primary

Materials information

Materials Type of material
Barite Ore
Galena Ore
Pyrite Ore
Sphalerite Ore
Calcite Gangue
Quartz Gangue

Alteration

  • (Local) Country rocks locally are sericitized and permeated with hydrothermal hematite.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -131.57576, 55.17374

Comments on the geologic information

  • 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-calcite-sulfide fissure veins as much as three feet thick, in sheared, siliceous phyllite, greenstone, rhyolite, and limestone (Karl, 1992, loc. 20a-f). Sulfide minerals, inferred from sample analyses, probably are mainly pyrite, galena, and sphalerite. Samples of sulfide-bearing quartz, calcite, and barite veins contained up to 20 ppm Ag, 2% Pb, more than 1% Zn, and 100 ppm Ni; a sample of limestone contained 1000 ppm Ba, 100 ppm Pb, and 500 ppm Zn; a sample of greenstone contained 200 ppm Zn, 100 ppm Co, 100 ppm Cr, and 100 ppm Ni; and samples of rhyolite and rhyolite tuff breccia contained up to 1 ppm Ag, 1% Ba, and 200 ppm Cu (Karl, 1992, loc. 20a-f).
  • Age = Fissure veins probably are Late Cretaceous or younger.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Samples of sulfide-bearing quartz, calcite, and barite veins contained up to 20 ppm Ag, 2% Pb, more than 1% Zn, and 100 ppm Ni; a sample of limestone contained 1000 ppm Ba, 100 ppm Pb, and 500 ppm Zn; a sample of greenstone contained 200 ppm Zn, 100 ppm Co, 100 ppm Cr, and 100 ppm Ni; and samples of rhyolite and rhyolite tuff breccia contained up to 1 ppm Ag, 1% Ba, and 200 ppm Cu (Karl, 1992, loc. 20a-f).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF KC170

Bibliographic references

  • 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,

  • 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.

  • 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.

Comments on the references

  • Primary Reference = Karl, 1992

General comments

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

Reporter information

Type Date Name Affiliation Comment
Reporter 07-JUL-99 H.C. Berg U.S. Geological Survey