Nixon Fork

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

Geologic information

Identification information

Deposit ID 10100969
MRDS ID A012420
Record type Site
Current site name Nixon Fork
Alternate or previous names Mespelt, Crystal, Garnet, High Grade, Mespelt Inclined Shaft, Recreation, Keen, Twin Shafts, Mespelt Main Shaft, Garnet Trench, Parsons and Strand, Southern Cross
Related records 10185958

Geographic coordinates

Geographic coordinates: -154.76684, 63.23837 (WGS84)
Relative position The Nixon Fork Mine is located at an elevation of approximately 1,400 feet (426 m) in Section 13, T. 26 S., R. 21 E., of the Kateel River Meridian. Location is precisely known as it is actively being mined. Reporter visited the site in 1996 and 1997.
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Geographic areas

Country State
United States Alaska

Commodities

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

Comments on the commodity information

  • Ore Material = unidentified U/Th minerals
  • Ore Material = Auriferous chalcopyrite
  • Ore Material = Auriferous pyrite
  • Ore Material = unidentified U/Th minerals.

Materials information

Materials Type of material
Chalcopyrite Ore
Azurite Ore
Bismuth Ore
Bornite Ore
Chalcocite Ore
Chrysocolla Ore
Electrum Ore
Malachite Ore
Scheelite Ore
Gold Ore
Pyrite Ore
Calcite Gangue
Chlorite Gangue
Epidote Gangue
Garnet Gangue
Limonite Gangue
Quartz Gangue
Sericite Gangue
Siderite Gangue
Zeolite Gangue

Alteration

  • (Local) Oxidation of sulfides probably resulted in some supergene enrichment of gold values

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) Eocene
  • 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) -154.76684, 63.23837

Comments on the geologic information

  • Geologic Description = The Nixon Fork gold mine is a series of small, rich contact metamorphic deposits in limestone within 100-150 m of a composite monzonite stock. The monzonite phase has yielded a 40K-40Ar biotite age of 68.0 Ma (Moll and others, 1981; Bundtzen and Miller, 1997). Younger (?) quartz porphyry bodies cut the monzonite along structures and form a distinctive border pahase of the monzonite pluton. ? the mineable ore bodies are copper-gold skarns that occur in irregular, structurally controlled zones in carbonate host rock with maximum dimensions of 66 feet (20 meters) along strike, 230 feet (70 meters) along rake, and are up to 16 feet (5 meters) wide (Freeman, 1996). Gangue minerals in the skarn zones include abundant garnet, diopside, epidote, and apatite. The ore bodies are lenticular, and are without well defined walls; some are probably hydrothermal replacement bodies that postdate skarn formation. Most metallic values and skarn occur as exoskarn 10 to 30 feet into the marble front; minor metallic bearing endoskarns occur within sattelite bodies of monzonite; however, most of this mineralization is not ore grade. Ore consists of auriferous chalcopyrite and pyrite with subordinate bornite and a little chalcocite that has been partly to thoroughly oxidized to a mixture of free gold and secondary copper minerals. The exception to this extensive 'supergene' oxidation process is the Crystal and Garnet Lodes (MD061), which consist mainly of unoxidized chalcopyrite, pyrite and bornite in a calcite, siderite and zeolite gangue. Gold fineness from the various Nixon Fork ore bodies range from 715 to 794 with silver being the major impurity.? the Nixon Fork mine is renowned for it's high grade gold ores. Mertie (1936) and Herreid (1966) report assay values from both surface and underground workings of up to 24.34 ounces/ton gold, 17.26 ounces/ton silver, 11.69 percent copper, and 1.40 percent bismuth. From 1920 to 1997, the mine has produced (from all operators) 119,956 ounces (3,730 kg) of gold, 19,566 (608 kg) ounces of silver, 1,235,443 pounds (560,396 kg) of copper, from about 99,765 tons (90,506 tonnes) of ore. The silver and copper production figures are incomplete and considered conservative.
  • Age = Age is probably Late Cretaceous, based on isotopic age of monzonite (Moll and others, 1981).

Economic information

Economic information about the deposit and operations

Development status Producer
Commodity type Metallic

Comments on exploration

  • Status = Active

Mining district

District name McGrath

Comments on the production information

  • Production Notes = Lode deposits were soon discovered in the area after the 1917 discovery of placer gold in the Hidden Creek basin. In 1920, T.P.Aitken produced the first ore--about 370 tons (335 tonnes). In 1921, the Treadwell-Yukon Mining Company, based in Juneau, Alaska, optioned the property from Aitken and mined for four years and milled 6,922 tons (6,280 tonnes) of ore. In 1925, the property reverted to owner E.M. Whalen, who produced ore on a fairly continuous basis until 1942. The property produced intermittently for six seasons from 1946 to 1961. Total production from 1920 to 1961 is estimated to be 36,016 ounces (933 kg) gold, and 1,836 ounces (57 kg) silver from 20,200 tons (18,325 tonnes) of ore. Prior to World War II, copper production (as a byproduct) was not accurately recorded; smelter returns that report a byproduct of copper are available for five operating years. In October, 1995, Nevada Consolidated Goldfields resumed production of the Nixon Fork Mine and through the end of 1997, produced 83,940 ounces 2,610 kg) gold, 17,730 ounces (551 kg) silver, and 1,194,000 pounds (541,598 kg) copper from 79,565 tons (72,180 tonnes) of ore. From 1920 to the end of 1997, the Nixon Fork Mine has been in production for 30 seasons, and produced 119,956 ounces (3,730 kg) gold, 19,566 ounces (608 kg) silver, and 1,235,443 pounds (560,396 kg) of copper from 99,765 tons (90,506 tonnes) of ore (production data from all previous operations was complied by the reporter). Silver and copper production figures are incomplete; hence totals for these latter metals are considered conservative. Mineral production data for the Nixon Fork Mineis not yet available for 1998.

Comments on the reserve resource information

  • Reserves = As of late 1997, exploration has replaced most of the ore mined from 1995 to 1997. In December, 1997, reserves stood at about 85,000 tons (77,112 tonnes) grading approximately 1.2 ounces/ton (41.1 grams/tonne) gold and undisclosed copper and silver (Swainbank and others, 1997).

Comments on the workings information

  • Workings / Exploration = Exploration and development took place intermittently from 1920 to 1961. After a hiatus of about 25 years, activities resumed in 1984 when Battle Mountain Mining Company leased claims from Ted Almasy and Margaret Mespelt, the owners. In 1989, Central Alaska Gold Company took over the leases and by 1994, had defined 91,200 tons (85,348 tonnes) of ore in several high grade bodies grading 1.42 ounces/ton (48.2 grams/tonne) gold and about 2.00 percent copper. Nevada Consolidated Goldfields resumed production in October, 1995 after a production hiatus of 34 years. (Bundtzen and others, 1996).? the Nixon Fork mine has been mined from at least 8 shafts with extensive branching levels and from a few pits and trenches; deepest mining was at 460-ft (140 m) level of garnet shaft in 1961 (Herreid, 1966). Some references report workings as deep as 600 ft below surface. Most shafts are about 100 ft (30 m) deep, with 2-3 levels; this includes two inclined shafts driven in early 1930's. Currently (1998) the mine is being worked through a spiral decline. The ore bodies currently being exploited are steeply inclined, structurally controlled chimneys. ? Maximum assays of 24.34 ounces/ton gold, 17.26 ounces/ton silver, 11.69 percent copper, and 1.4 percent bismuth have been reported in the literature (Mertie, 1936).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012420
USGS Alaska Resource Data File ARDF MD062

Bibliographic references

  • Deposit

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

  • Deposit

    Williams, J.A., 1961, Report of the Division of Mines and Minerals for the year 1961: Alaska Division of Mines and Minerals Annual Report 1961, 108 p.

  • Deposit

    Patton, W.W., Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L., and Chapman, R.M., 1980, Preliminary geologic map of Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811-A, 1 sheet, scale l:250,000.

  • 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

    Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Economic Geology Monograph #9, Mineral Deposits of Alaska, p. 242-286.

  • Deposit

    Swainbank, R.C., Bundtzen, T. K., Clough A.H., and Henning, M.W., 1997, Alaska's mineral industry 1996: Alaska Division of Geological and Geophysical Surveys Special Report 51, 68 p.

  • Deposit

    King, H.D., Risoli, D.A., Cooley, E.F., O'Leary, R.M., Speckman, W.A., Speisman, D.L., and Galland, D.W., 1980, Final results and statistical summary of analyses of geochemical samples from the Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811F, 134 pages.

  • 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.

  • Deposit

    Bundtzen, T.K., Swainbank, R.C., Clough, A.H., Henning, M.W., and Hansen, E.W., 1994, Alaska's mineral industry, 1993: Alaska Division of Geological and Geophysical Surveys Special Report 48, 84 p.

  • Deposit

    Bundtzen, T.K., Swainbank, R.C., Clough, A.H., Henning, M.W., and Charlie, K.M., 1996, Alaska's mineral industry, 1995: Alaska Division of Geological and Geophysical Surveys Special Report 50, 72 p.

Comments on the references

  • Primary Reference = Herreid, 1966

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 Crystal (MD061) and Whalen Glory Hole (MD071) mines.

Reporter information

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