Unnamed (near Geyser Creek)

Occurrence in Alaska, United States with commodities Silver, Gold, Arsenic, Mercury

Geologic information

Identification information

Deposit ID 10308466
Record type Site
Current site name Unnamed (near Geyser Creek)

Geographic coordinates

Geographic coordinates: -168.50237, 53.19907 (WGS84)
Relative position This site is located near Geyser Creek on Umnak Island, approximately 3 miles southeast of Geyser Bight. Simpson's (1986) location of this site is vague and it could correspond to locations G or L which are mapped as clusters of hot-springs (Nye and others, 1992). The location is probably accurate to within 2 miles.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Gold Primary
Arsenic Secondary
Mercury Secondary

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Quartz Gangue


  • (Local) The volcanic rocks exhibit regional propylitic alteration and local intense argillic alteration and weak silicification. The clay zones contain up to 2 percent pyrite and thin, discontinuous quartz veins.

Mineral occurrence model information

Model code 104
USGS model code 25a
Deposit model name Hot-spring Au-Ag
Mark3 model number 45

Nearby scientific data

(1) -168.50237, 53.19907

Comments on the geologic information

  • Geologic Description = Geothermal activity at this site is indicated by a 800 x 2000 foot color anomaly (Simpson, 1986). The rocks here consist of propylitized andesitic flows, tuffs, and volcaniclastics of Pleistocene age. The altered rocks exhibit local zones of intense argillization and weak silicification. The clay zones contain up to 2 percent disseminated pyrite. Nye and others (1992) report dioritic and monzonitic plutons at low elevations on the east and west walls of the lower half of Geyser Creek valley, and they speculate that the plutons may host the geothermal reservoir system. Analyses of 20 rock samples indicated values up to 150 ppm arsenic, 0.58 ppm gold, 1.25 ppm mercury, and 0.2 ppm silver (Simpson, 1985, table 11, pg. 38). In general, the only rocks which contain gold are those which exhibit pyritization and moderate silicification. There does not appear to be any lateral or vertical zonation of the metals.
  • Age = Quaternary.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Aleutian Islands

Comments on the workings information

  • Workings / Exploration = Twenty samples collected by Kennecott were found to contain 8 to150 ppm arsenic, 0.005 to 0.58 ppm gold, 0.005 to 1.25 ppm mercury, and 0.2 to 0.6 ppm silver (Simpson, 1986).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF UK004

Bibliographic references

  • Deposit

    Nye, C.J., Motyka, R.J., Turner, D.L., and Liss, S.A., 1992, Geology and geochemistry of the Geyser Bight geothermal area, Umnak Island, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigation 92-1, 85 p., 2 map sheets, scale 1/24,000.

  • Deposit

    Simpson, D.F., 1986, Aleutian Islands project, 1985 final report: Kennecott-Alaska Exploration Company, 54 p. (Report held by the Aleut Native Corporation, Anchorage, Alaska).

Comments on the references

  • Primary Reference = Simpson, 1986

General comments

Subject category Comment text
Deposit Model Name = Hot-spring Au-Ag (Cox and Singer, 1986; model 25a)
Deposit Other Comments = This site is on land selected by the Aleut Native Corporation.

Reporter information

Type Date Name Affiliation Comment
Reporter 27-JAN-00 S.H. Pilcher U.S. Geological Survey