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Unnamed (near Red Mountain)

Occurrence in Alaska, United States with commodities Copper, Lead, Silver
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Geologic information

Identification information

Deposit ID 10307676
Record type Site
Current site name Unnamed (near Red Mountain)

Geographic coordinates

Geographic coordinates: -131.56976, 55.25074 (WGS84)
Relative position This site represents six occurrences on and near Red Mountain on northern Annette Island. The occurrences are in sections 21, 27, and 34, T. 76 S., R. 91 E., of the Copper River Meridian. They are at elevations ranging from about 500-2000 feet, and are distributed along a northwest-trending line 1.7 miles long, that extends from the southeast foot of Red Mountain to the northwest foot. The coordinates are for the approximate center of the estimated two-square-mile area that contains these occurrences. The site corresponds to loc. 4a-f in Karl (1992). The location is accurate within 0.2 mile.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Lead Primary
Silver Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Pyrite Ore
Pyrrhotite Ore

Alteration

  • (Local) Sulfidization of country rocks.

Host and associated rocks

  • Host or associated Host
    Stratigraphic age (youngest) Cretaceous
    Stratigraphic age (oldest) Late Jurassic

Nearby scientific data

(1) -131.56976, 55.25074
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Comments on the geologic information

  • Geologic Description = The country rocks in the area of Red Mountain are Upper Jurassic or Cretaceous andesitic or basaltic metavolcanic rocks that are gradationally interbedded with subordinate flyschlike metasedimentary rocks (Berg, 1972 [I 684]; Berg and others, 1988). The bedded rocks are intruded by a Jurassic or Cretaceous diorite stock and related dikes. The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The occurrences consist of ubiquitously disseminated pyrite and pyrrhotite in metadiorite, argillite, metagraywacke, and metatuff (Karl, 1992, loc. 4a-f). The sulfides commonly make up as much as 10 volume percent, and locally up to 40 volume percent, of the hostrocks. In places, a little galena or chalcopyrite accompany the other sulfides. . A sample of augite crystal metatuff contained 1.5 ppm Ag; samples of the metadiorite contained up to 700 ppm Cu and 100 ppm Pb; a sample of slate contained 10 ppm Mo; and samples of phyllitic gritstone and sandstone contained up to 200 ppm Pb (Karl, 1992, loc. 4a-f). The distribution and setting of the disseminated sulfide mineralization suggest that it may in part be cogenetic with Late Jurassic or Cretaceous deposition of the volcanic-sedimentary hostrocks.
  • Age = Disseminated sulfide mineralization may in part be cogenetic with Late Jurassic or Cretaceous deposition of volcanic-sedimentary hostrocks.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = A sample of augite crystal metatuff contained 1.5 ppm Ag; samples of the metadiorite contained up to 700 ppm Cu and 100 ppm Pb; a sample of slate contained 10 ppm Mo; and samples of phyllitic gritstone and sandstone contained up to 200 ppm Pb (Karl, 1992, loc. 4a-f).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF KC161

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 = Disseminated sulfide deposit of volcanogenic origin?

Reporter information

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