DeCourcy Mountain

Past Producer in Alaska, United States with commodities Mercury, Antimony

Geologic information

Identification information

Deposit ID 10002607
MRDS ID A015044
Record type Site
Current site name DeCourcy Mountain
Alternate or previous names Decourcy Mt. Mine
Related records 10185409

Geographic coordinates

Geographic coordinates: -158.46596, 62.06244 (WGS84)
Relative position USGS MF-363, Loc. 1. 2 miles south of Decourcy Mtn. mine marked on Iditarod (A-5).; Accurate within 1/4 mile.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Mercury Primary
Antimony Secondary

Comments on the commodity information

  • Gangue = Silica-carbonate
  • Gangue = clay minerals

Materials information

Materials Type of material
Cinnabar Ore
Stibnite Ore

Alteration

  • (Local) Igneous and sedimentary rocks are extensively altered to silica-carbonate rock.

Mineral occurrence model information

Model code 176
USGS model code 27
Deposit model name Disseminated epithermal mercury antomony

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Siltstone
    Rock unit name Kuskokwim Group;Kuskokwim Group;
    Rock description Kuskokwim Group;Kuskokwim Group;

Nearby scientific data

(1) -158.46596, 62.06244

Comments on the geologic information

  • Geologic Description = Cinnabar and minor stibnite in a gangue of silica, carbonate, and clay minerals. Ore minerals occur in small irregular lenses, veins, and stockworks localized in breccia, along contacts between igneous and sedimentary rocks, and along bedding surfaces. The ore bodies are in or near hydrothermally altered diabase sills. Ore bodies pinch and swell from a few inches to over a foot, and were formed by both open space filling and replacement.
  • Age = Tertiary

Economic information

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Iditarod

Comments on the production information

  • Production Notes = Discovered in 1910-11; staked in 1919; operated intermittently 1920-50. Produced an estimated 1500 flasks of Hg

Comments on the reserve resource information

  • Reserves = Inferred reserves of several thousand flasks.

Comments on the workings information

  • Workings / Exploration = Surface and underground: About 1,375 ft. of adits and minor drifts, crosscuts, and stopes; surface pits and trenches.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A015044
USGS Alaska Resource Data File ARDF ID158

Bibliographic references

  • Deposit

    Cady, W.M., Wallace, R.E., Hoare, J.M., and Webber, E.J., 1955, The central Kuskokwim region, Alaska: U.S. Geological Survey Professional Paper 268, 132 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., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction material) in the Iditarod and Ophir quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-576, 101 p.

  • Deposit

    Miller, M.L., Bundtzen, T.K., Keith, W.J., Bailey, E.A., Bickerstaff, Damon, 1996, Geology and mineral resources of the Stuyahok area, part of Holy Cross A-4 and A-5 quadrangles, Alaska: U.S. Geological Survey Open-File Report 96-505-A, 30 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Iditarod quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-363, 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Sainsbury and MacKevett, 1965

General comments

Subject category Comment text
Deposit Model Name = Epithermal vein,?: mercury-antimony

Reporter information

Type Date Name Affiliation Comment
Reporter 25-MAY-94 Powers, M.T. U.S. Geological Survey
Reporter 25-MAY-94 Huber, D.F. U.S. Geological Survey
Reporter 25-MAY-94 Miller, M.L. U.S. Geological Survey