Nixon Fork

The Nixon Fork is a gold, copper, and silver mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Nixon Fork
Secondary: Mespelt
Secondary: Crystal
Secondary: Garnet
Secondary: High Grade
Secondary: Mespelt Inclined Shaft
Secondary: Recreation
Secondary: Keen
Secondary: Twin Shafts
Secondary: Mespelt Main Shaft
Secondary: Garnet Trench
Secondary: Parsons and Strand
Secondary: Southern Cross

Commodity

Primary: Gold
Primary: Copper
Primary: Silver
Secondary: Tungsten
Secondary: Uranium
Secondary: Bismuth
Secondary: Thorium

Location

State: Alaska
District: McGrath

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Skarn Cu

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Oxidation of sulfides probably resulted in some supergene enrichment of gold values

Rocks

Name: Quartz Monzonite
Role: Associated
Age Type: Associated Rock
Age Young: Eocene

Analytical Data

Not available

Materials

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

Comments

Comment (Commodity): Ore Material = Auriferous chalcopyrite

Comment (Commodity): Ore Material = Auriferous pyrite

Comment (Deposit): Model Name = Copper-gold skarn (Cox and Singer, 1986; model no. 18b)

Comment (Deposit): Other Comments = See Nixon Fork Crystal (MD061) and Whalen Glory Hole (MD071) mines.

Comment (Commodity): Ore Material = unidentified U/Th minerals.

Comment (Reference): Primary Reference = Herreid, 1966

Comment (Reserve-Resource): 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).

Comment (Geology): Age = Age is probably Late Cretaceous, based on isotopic age of monzonite (Moll and others, 1981).

Comment (Commodity): Ore Material = unidentified U/Th minerals

Comment (Exploration): Status = Active

Comment (Workings): 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).

Comment (Production): 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.

Comment (Geology): 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.

References

Reference (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.

Reference (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.

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

Reference (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.

Reference (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.

Reference (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.

Reference (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.

Reference (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.

Reference (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.

Reference (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.

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