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Kagati Lake

Prospect in Alaska, United States with commodities Gold, Mercury, Antimony
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Geologic information

Identification information

Deposit ID 10000257
MRDS ID A010299
Record type Site
Current site name Kagati Lake
Related records 10136722

Geographic coordinates

Geographic coordinates: -159.91274, 59.9193 (WGS84)
Relative position The Kagati Lake prospect is in uplands in the headwaters of Atmugiak Creek, 5.5 miles northeast of Kagati Lake. It is at an elevation of about 3,400 feet above the small, east-headwater lake to Atmugiak Creek. It is locality 1 of Hoare and Cobb (1977) and of Cobb and Condon (1972).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Mercury Primary
Antimony Primary

Materials information

Materials Type of material
Cinnabar Ore
Orpiment Ore
Realgar Ore
Stibnite Ore
Calcite Gangue
Quartz Gangue
Tourmaline Gangue

Alteration

  • (Local) Silicification and oxidation.

Host and associated rocks

  • Host or associated Host
    Chronological age 71.1
    Uncertainty 2.1
    Dating method K-Ar
    Type of media Biotite
    Stratigraphic age (youngest) Late Cretaceous

Nearby scientific data

(1) -159.91274, 59.9193
ListMap

Comments on the geologic information

  • Geologic Description = The Kagati Lake prospect is within a Cretaceous granitic pluton (Hoare and Coonrad, 1978). It was discovered and prospected by 1927 (Malone, 1962) but explored mostly in the 1950s (Sainsbury and MacKevett, 1965). North-northwest-trending fractures and shear zones up to 1,200 feet long and approximately parallel to steep joints in the host granitic rock control mineralization. Cinnabar, some closely associated with realgar, stibnite, and minor orpiment, forms veinlets and fills fractures in the shear zones. Individual cinnabar masses are 2 to 24 inches wide, but are observed only for lengths up to 10 feet due to limited exposure. Quartz, some vuggy, and clay accompany the cinnabar; secondary antimony minerals and iron-oxides are also present. Frost (1990, p. C5) describes the veins as zoned with margins of blue-green to brown tourmaline needles extending into a core of quartz and calcite; cinnabar and stibnite crystals with some realgar and orpiment are scattered through quartz in the cores of the veins. Gold values up to 2.9 ppm were obtained on vein material (Frost, 1990; Gray and others, 1990).
  • Age = Chron age is for host rock.
  • Age = Late Cretaceous or Tertiary. The mineralization postdates the host granitic pluton, which yielded a K/Ar age of 71.1 +/- 2.1 Ma on biotite (Hoare and Coonrad, 1978).

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Bethel

Comments on the workings information

  • Workings / Exploration = Exploration includes pits, trenches, and dozer stripping; surface mapping was completed in the 1950s (Sainsbury and MaKevett, 1965).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A010299
USGS Alaska Resource Data File ARDF GO011

Bibliographic references

  • Deposit

    Malone, Kevin, 1962, Mercury occurrences in Alaska: U.S. Bureau of Mines Circular 8131, 57 p.

  • Deposit

    Sainsbury, C.L. and MacKevett, E.M., Jr., 1965, Quicksilver deposits of southwestern Alaska: U.S. Geological Survey Bulletin 1187, 89 p.

  • Deposit

    Cobb, E.H., and Condon, W.H., 1972, Metallic mineral resources map of the Goodnews quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-447, scale 1:250,000.

  • Deposit

    Hoare, J.M., and Cobb, E.H., 1977, Mineral occurrences (other than mineral fuels and construction materials) in the Bethel, Goodnews, and Russian Mission quadrangles, Alaska: U.S. Geological Survey Open-File Report 77-156, 98 p.

  • Deposit

    Hoare, J.M., and Coonrad, W.L., 1978, Geologic map of the Goodnews and Hagemeister Island quadrangles region, southwestern Alaska: U.S. Geological Survey Open-File Report 78-9-B, two sheets, scale 1:250,000.

  • Deposit

    Frost, T.P., 1990, Geology and geochemistry of mineralization in the Bethel quadrangle, southwestern Alaska, in Goldfarb, R. J., Nash, J. T., and Stoeser, J. W., eds., Geochemical studies in Alaska by the U.S. Geological Survey, 1989: U.S. Geological Survey Bulletin 1950, p. C1-C9.

  • Deposit

    Gray, J.E., Frost, T.P., Goldfarb, R.J., and Detra, D.E., 1990, Gold associated with cinnabar- and stibnite-bearing deposits and mineral occurrences in the Kuskokwim River Region, Alaska, in Goldfarb, R. J., Nash, J. T., and Stoeser, J. W., eds., Geochemical studies in Alaska by the U. S. Geological Survey, 1989: U.S. Geological Survey Bulletin 1950, p. D1-D6.

Comments on the references

  • Primary Reference = Sainsbury and MacKevett, 1965

General comments

Subject category Comment text
Deposit Model Name = Epithermal mercury- and antimony-bearing veins in granitic rock

Reporter information

Type Date Name Affiliation Comment
Reporter 20-MAR-2001 Travis L. Hudson Applied Geology