Nixon Fork - Crystal

Past Producer in Alaska, United States with commodities Silver, Gold, Bismuth, Copper, Tungsten

Geologic information

Identification information

Deposit ID 10000473
MRDS ID A010652
Record type Site
Current site name Nixon Fork - Crystal
Alternate or previous names Garnet Extension

Geographic coordinates

Geographic coordinates: -154.77684, 63.23837 (WGS84)
Relative position The Nixon Fork - Crystal and Garnet Extension mines are about 2,000 feet west of the Nixon Fork Mine (MD062), in Section 13, T. 26 S., R. 21 E., of the Kateel River Meridian. The reporter visited the site in 1995 and 1996.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Gold Primary
Bismuth Secondary
Copper Secondary
Tungsten Secondary

Comments on the commodity information

  • Ore Material = Auriferous pyrite
  • Ore Material = Bismuth (native)

Materials information

Materials Type of material
Arsenopyrite Ore
Bismuth Ore
Chalcopyrite Ore
Scheelite Ore
Gold Ore
Pyrite Ore
Epidote Gangue
Magnetite Gangue


  • (Local) Extensive oxidation of primary sulfides.

Mineral occurrence model information

Model code 59
USGS model code 18b
Deposit model name Skarn Cu
Mark3 model number 8

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Quartz Monzonite
    Stratigraphic age (youngest) Pliocene
    Stratigraphic age (youngest) Late Permian
  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Quartz Latite
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone

Nearby scientific data

(1) -154.77684, 63.23837

Comments on the geologic information

  • Geologic Description = The Nixon Fork - Crystal and Garnet Extension mines consist of locally gold-rich, contact metamorphic deposits in Paleozoic limestone, generally within a few feet of quartz monzonite contact. Although most ores are locally enriched by oxidation, the Crystal and Garnet Extension were distinguished from other ore bodies in the Nixon Fork Mine area by preservation of primary gold-bearing sulfide oe bodies. The deposits consist of chalcopyrite, pyrite, and bornite in a gangue of calcite, siderite, and zeolites. Hence the Crystal and Garnet extension deposits are considered unoxidized extensions of the Nixon Fork lode system (MD062). Age is probably Late Cretaceous, based on isotopic age (71.0 Ma) of associated monzonite (Moll and others, 1981). Assay data is summarized with the Nixon Fork mine (MD062).
  • Age = Age is probably Late Cretaceous, based on isotopic age (71.0 Ma) of associated monzonite (Moll and others, 1981).

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 McGrath

Comments on the production information

  • Production Notes = Production included with Nixon Fork Mine (MD062).

Comments on the workings information

  • Workings / Exploration = The Nixon Fork Crystal and Garnet mines were discovered at the same time as the main Nixon Fork Deposit (MD062) in 1917 or 1918. The small but rich gold-skarn deposits were developed mainly by inclined shafts with branching levels.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A010652
USGS Alaska Resource Data File ARDF MD061

Bibliographic references

  • Deposit

    Martin, G.C., 1922, Gold lodes in the Upper Kuskokwim region: U.S. Geological Survey Bulletin 864D, p. 149-161.

  • Deposit

    Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, 115-245.

  • Deposit

    Freeman, Larry, 1996, A progress report on the Nixon Fork underground gold mine, McGrath-McKinley district, Alaska [abs]: Abstract preprint of the 15th Biennial Conference on Alaskan Mining, Alaska Miners Association, Fairbanks, Alaska, p. 36.

  • Deposit

    Herreid, G.H., 1966, Geology and geochemistry of the Nixon Fork area, Medfra quadrangle, Alaska: Alaska Division of Mines and Minerals Geologic Report 22, 34 p., 1 sheet, scale 1:40,000.

Comments on the references

  • Primary Reference = Mertie, 1936

General comments

Subject category Comment text
Deposit Model Name = Copper-gold skarn (Cox and Singer, 1986; model no. 18b)
Deposit Other Comments = See Nixon Fork Mine (MD062).

Reporter information

Type Date Name Affiliation Comment
Reporter 07-JUN-98 Bundtzen, T.K. Pacific Rim Geological Consulting