Unnamed (west of Crab Bay)

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

Geologic information

Identification information

Deposit ID 10001624
MRDS ID A012388
Record type Site
Current site name Unnamed (west of Crab Bay)
Alternate or previous names Tyee?

Geographic coordinates

Geographic coordinates: -131.39869, 55.11085 (WGS84)
Relative position This site includes a roughly 0.3-mile-long line of occurrences and a prospect pit, at elevations of about 200 to 300 feet, midway between the outlet of 'Sink Lake' and the head of Crab Bay. The pit and occurrences are in section 16, T. 78 S., R. 93 E., of the Copper River Meridian, and the map coordinates are for the approximate center of the line. The site corresponds to loc. 5 in Berg (1972 [I 684]), loc. 146 in Elliott and others (1978), and loc. 33a-c in Karl (1992). The location is accurate within 0.1 mile.? Also see Additional comments.
(click for info)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Lead Primary
Zinc Primary
Barium-Barite Secondary

Materials information

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

Alteration

  • (Local) Local silicification, sericitization, and dolomitization; minor oxidation of copper minerals.

Mineral occurrence model information

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

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Stratigraphic age (youngest) Late Permian

Nearby scientific data

(1) -131.39869, 55.11085

Comments on the geologic information

  • Geologic Description = The country rocks in the area of this site are recrystallized rhyolite and overlying, locally dolomitic, limestone (Berg, 1972). These Upper Triassic rocks are complexly folded and faulted, and were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.? the occurrences consist of quartz pods and fissure veins up to about a foot thick in carbonate and volcanic rocks, and of quartz-calcite-barite veins in locally silicified carbonate rock (Karl, 1992, loc. 33). In addition to barite, these veins contain white mica, pyrite, sphalerite, and galena. ? At and near a prospect pit, samples of brecciated, dolomitic limestone carrying stringers and disseminated grains of pyrite, galena, and chalcopyrite; of nearby sulfide quartz veins; and of sheared pyritic rhyolite at the limestone contact contained as much as 0.05 ppm Au, 70 ppm Ag, 1000 ppm Pb, more than 1% Zn, 20 ppm Mo, and more than 5000 ppm Ba (Berg, 1972, loc. 5; Karl, 1992, loc. 33c). ? Reports based on fieldwork by private interests in the 1970s describe a mineralized zone 150 feet wide and 450 feet long at a rhyolite-dolomite contact. The zone contains quartz veins carrying galena, sphalerite, tetrahedrite?, and malachite (Karl, 1992, loc. 33). Another 150-foot by 450-foot zone in dolomite locally contains disseminated sulfides that assay up to 8% lead and zinc, as well as quartz veins containing sphalerite and galena. Two soil samples in rhyolite near the dolomite contained detectable gold; and pyritic limestone contained 150 ppm Pb.
  • Age = The fissure veins probably are Late Cretaceous or younger in age.

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = Prospect pit, probably dating to the 1930s. Samples at and near this pit contained as much as 0.05 ppm Au, 70 ppm Ag, 1000 ppm Pb, more than 1% Zn, 20 ppm Mo, and more than 5000 ppm Ba (Berg, 1972, loc. 5; Karl, 1992, loc. 33c). ? Reports based on fieldwork by private interests in the 1970s describe a mineralized zone 150 feet wide and 450 feet long at a rhyolite-dolomite contact. The zone contains quartz veins carrying galena, sphalerite, tetrahedrite?, and malachite (Karl, 1992, loc. 33). Another 150-foot by 450-foot zone in dolomite locally contains disseminated sulfides that assay up to 8% lead and zinc, as well as quartz veins containing sphalerite and galena. Two soil samples in rhyolite near the dolomite contained detectable gold; and pyritic limestone contained 150 ppm Pb.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012388
USGS Alaska Resource Data File ARDF KC150

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

    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.

  • Deposit

    Cobb, E.H., and Elliott, R.L., 1980, Summaries of data on and lists of references to metallic and selected nonmetallic mineral deposits in the Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-1053, 154 p.

  • 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)
Deposit Other Comments = Early references to the Tyee prospect on Annette Island may refer to this site (Cobb and Elliott, 1980, p. 30).

Reporter information

Type Date Name Affiliation Comment
Reporter 06-JUL-1999 H.C. Berg U.S. Geological Survey