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Red Mountain

Prospect in Alaska, United States with commodities PGE, Gold, Chromium, Copper, Nickel, Gold, Chromium
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Geologic information

Identification information

Deposit ID 10002299
MRDS ID A013204
Record type Site
Current site name Red Mountain
Related records 10258611

Geographic coordinates

Geographic coordinates: -161.73268, 58.93925 (WGS84)
Relative position This prospect is on the east side of Red Mountain on the ridge between Boulder and Squirrel Creek drainages. The map site is at the approximate center of a large soil geochemistry anomaly at an elevation of about 1,000 feet. It is accurately located.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
PGE Primary
Gold Secondary
Chromium Tertiary
Copper Tertiary
Nickel Tertiary
Gold Secondary
Chromium Secondary

Comments on the commodity information

  • Ore Material = platinum group metal (PGM) alloys

Materials information

Materials Type of material
Chromite Ore
Gold Ore

Alteration

  • (Local) Partial to complete serpentization of the dunite is common. Mertie (1969, p. 79) reports that 25 percent of the Red Mountain dunite is serpentine.

Mineral occurrence model information

Model code 23
USGS model code 9
Deposit model name Alaskan Cr-Pt (PGE)
Mark3 model number 120

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite > Dunite
    Rock unit name Goodnews Bay Ultramafic Complex;Goodnews Bay Ultramafic Complex;Goodnews Bay Ultramafic Complex
    Rock description Goodnews Bay Ultramafic Complex;Goodnews Bay Ultramafic Complex;Goodnews Bay Ultramafic Complex

Nearby scientific data

(1) -161.73268, 58.93925
ListMap

Comments on the geologic information

  • Geologic Description = Red Mountain is a large, composite ultramafic pluton of Jurassic age (Hoare and Coonrad, 1978). It is dominantly dunite with a thin border zone assemblage of peridotite, clinopyroxenite, and hornblende-bearing rocks (Southwith, 1986; Southwith and Foley, 1986; Alaska Earth Sciences, 2000). This prospect is in dunite between the crest of Red Mountain and the eastern border zone of the pluton. It is defined by a soil-geochemistry anomaly that is 1,700 meters (5,600 feet) long and 700 meters (2,300 feet) wide. Platinum values in this anomaly range from 60 to 3,300 ppb (Alaska Earth Sciences, 2000). Bird and Clark (1976, Table 4, p. 724) reported Red Mountain sample results of up to 1.4 ppm Pt, 0.020 ppm Pd, 0.0300 ppm Rh, and 0.300 ppm Ir. Fechner (1988, p. 43) reported Red Mountain sample results of up to 1.681 ppm Pt, 0.515 ppm Pd, 0.117 ppm Rh, and 0.823 ppm Ir.? Chromite occurs as disseminations and layers in the dunite. Platinum-bearing alloys have been identified as inclusions in chromite (Bird and Clark, 1976) and as separate grains in heavy mineral concentrate from residual materials over dunite (Fechner, 1988). Three samples of heavy-mineral concentrate contained a trace to 0.0011 ounce of PGM per cubic yard and a trace to 0.0002 ounce of gold per cubic yard. Platinum was recovered from concentrates of residual materials over dunite sampled near the crest of Red Mountain by the Goodnews Bay Mining Company in 1965 (Mertie, 1969, p. 84). The platinum-bearing alloy inclusions in chromite comprise 20 percent platinum, 40 percent iridium, 25 percent iron and lesser amounts of rhodium, nickel, and chromium (Bird and Clark, 1976, p. 724).
  • Age = Jurassic, the age of the Red Mountain ultramafic pluton. Hoare and Coonrad (1978) report K/Ar ages for two samples of amphibole from the southeast border of the Red Mountain pluton: 176.4 +/- 5.3 Ma and 186.9 +/- 5.6 Ma.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Active

Mining district

District name Goodnews Bay

Comments on the workings information

  • Workings / Exploration = A surface soil and rock geochemical survey has been completed over a large part of the Red Mountain dunite. An aeromagnetic survey was flown over the Salmon River (Goodnews) area in 1994, a gravity survey has been completed, and some controlled-source audio magneto-telluric lines have been run over selected parts of the ultramafic complex (Alaska Earth Sciences, 2000). A portable washing plant was used for trial placer prospecting of residual material on the crest of Red Mountain in 1965.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013204
USGS Alaska Resource Data File ARDF HG006

Bibliographic references

  • Deposit

    Mertie, J.B., Jr., 1969, Economic geology of platinum minerals: U.S. Geological Survey Professional Paper 630, 120 p.

  • Deposit

    Mertie, J.B., Jr., 1976, Platinum deposits in the Goodnews Bay district, Alaska: U.S. Geological Survey Professional Paper 938, 42 p.

  • Deposit

    Bird, M.L., and Clark, A.L., 1976, Microprobe study of olivine chromitites of the Goodnews Bay ultramafic complex, Alaska, and the occurrence of platinum: U.S. Geological Survey Journal of Research, v. 4, p. 717-725.

  • 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

    Southwith, D.P., 1986, Geology of the Goodnews Bay ultramafic complex: University of Alaska, Fairbanks, M.Sc. thesis, 115 p.

  • Deposit

    Southwith, D.P., and Foley, J.Y., 1986, Lode platinum-group metals potential of the Goodnews Bay ultramafic complex, Alaska: U.S. Bureau of Mines Open-File Report 51-86, 82 p.

  • Deposit

    Fechner, S.A., 1988, Bureau of Mines mineral investigation of the Goodnews Bay mining district, Alaska: U.S. Bureau of Mines Open-File Report 1-88, 230 p.

  • Deposit

    Alaska Earth Sciences, 2000, The Goodnews Bay ultramafic complexes: Unpublished data, http://aes.alaska.com/UMAF/FIGURES/page4.html

Comments on the references

  • Primary Reference = Alaska Earth Sciences, 2000

General comments

Subject category Comment text
Deposit Model Name = Alaskan PGE (Cox and Singer, 1986; model 9)
Deposit Other Comments = the Red Mountain dunite is probably the major source of platinum metals in the placer deposits of the Salmon River drainage.

Reporter information

Type Date Name Affiliation Comment
Reporter 18-MAR-2001 Travis L. Hudson Applied Geology