Salmon River

Producer in Alaska, United States with commodities Gold, Chromium, Diamond, Mercury

Geologic information

Identification information

Deposit ID 10308863
MRDS ID A013215
Record type Site
Current site name Salmon River
Related records 10002307

Geographic coordinates

Geographic coordinates: -161.71268, 58.90925 (WGS84)
Relative position This placer mine is located in the present valley of Salmon River. Salmon River is the main drainage on the east side of Red Mountain. Its mouth is on Kuskokwim Bay approximately 10 miles south of the community of Platinum. Dredge mining took place from the mouth of Boulder Creek (HG026), a west tributary, south about five miles to within 11/4 mile of the mouth of the river. The dredge tailings are a few hundred feet wide and confined to the active drainage. The map site is at the approximate midpoint of the dredge tailings. This mine is included in locality 12 of Cobb (1972 [MF 362]; 1980 [OF 80-909]).
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Geographic areas

Country State
United States Alaska


Commodity Importance
Gold Primary
Chromium Secondary
Diamond Secondary
Mercury Secondary

Materials information

Materials Type of material
Chromite Ore
Cinnabar Ore
Diamond Ore
Gold Ore
Ilmenite Ore
Magnetite Ore
Mercury Ore
Sperrylite Ore
Tetraferroplatinum Ore

Mineral occurrence model information

Model code 120
USGS model code 39b
BC deposit profile C01. C02
Deposit model name Placer PGE-Au

Nearby scientific data

(1) -161.71268, 58.90925

Comments on the geologic information

  • Geologic Description = This placer mine is located in the present valley of Salmon River. Dredge mining took place from the mouth of Boulder Creek (HG026), a west tributary, south about five miles to within 11/4 mile of the mouth of the river. The dredge tailings are commonly few hundred feet wide and confined to the active drainage. The paystreak was 300 to 450 feet wide, except near the mouth of Platinum Creek (HG014) where it was up to 600 feet wide (Mertie, 1969, p. 82). Overburden gravel, sand, and silt deposits vary from 30 to 80 feet thick and do not change systematically in thickness. The gravels are mostly well-rounded pebbles and cobbles up to 2 feet across interbedded with sand and silt; clay is not present. The pay is on an uneven, non-weathered bedrock surface that is locally incised up to 20 feet; in the overlying 2 feet of gravels; and in 2 feet of fractured bedrock. The tenor of the worked paystreak was 0.002 to 0.026 ounce of PGM per cubic yard (Fechner, 1988). PGM grains become smaller southward through the Salmon River valley paystreak, from 0.2 to less than 0.002 inch in diameter. Four samples of tailings from this mine contained up to 0.0037 ounce of PGM per cubic yard (Fechner, 1988, p. 190, 193). PGM grains from Salmon River valley and bench tailings contain 0.6 to 1.1 percent Rh, 0.4 to 0.7 percent Ru, 60.3 to 85.5 percent Pt, 3.8 to 25.6 percent Ir, 1.2 to 6.3 percent Os and 5.9 to 8.9 percent Fe (Fechner, 1988, p. 81). The PGM-bearing phases identified in these samples included iron-platinum alloy containing 8 to 30 percent Fe; iron-platinum alloy with minor osmiridium inclusions; and osmiridium, sperrylite, and tetraferroplatinum (Fechner, 1988, p. 81). Small amounts of cinnabar and traces of native mercury have been identified in dredge concentrates (Mertie, 1976, p. 38). Two small diamonds were identified in the nondissolved residue from 8 PGM granules (Mertie, 1976, p. 17). The Salmon River vally placer is continuous with the placer in Platinum Creek (HG014) and with the placers in some of its other west tributaries. The paystreak apparently ends or becomes uneconomic at the south end of the mine workings. The workings are all below surface elevations of 150 feet and their proximity to the coastline and low elevation suggests that Quaternary sea level changes could have influenced placer development.
  • Age = Quaternary.

Economic information

Economic information about the deposit and operations

Development status Producer
Commodity type Metallic

Comments on exploration

  • Status = Active

Mining district

District name Goodnews Bay

Comments on the production information

  • Production Notes = A large part of the 650,000 ounces of PGM and 15,600 ounces of Au produced from the Salmon River area was recovered from this placer.

Comments on the reserve resource information

  • Reserves = Inasmuch as the recovery efficiency of the dredge operations was about 60 percent, the mine tailings are a low-grade resource. Fechner (1988, p. 27) estimates that over 40 million cubic yards of tailings are present that could contain 0.0013 to 0.017 ounce of PGM per cubic yard.

Comments on the workings information

  • Workings / Exploration = The Salmon River valley paystreak was worked by dredge starting in 1937, and several parallel cuts totaling approximately 15 to 20 miles of workings up to 60 feet deep have been made. Considerable exploration drilling was completed to delineate the paystreak.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF HG012
USGS Mineral Resources Data System MRDS A010735
USGS Mineral Resources Data System MRDS A013215
USGS Mineral Resources Data System MRDS M045371

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

    Cobb, E.H., 1980, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File Report 80-909, 103 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

    Cobb, E.H., 1972, Metallic mineral resources map of the Hagemeister Island quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-362, 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Mertie, 1976

General comments

Subject category Comment text
Deposit Model Name = Placer PGE-Au (Cox and Singer, 1986; model 39b)

Reporter information

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