Amaknak Island

Occurrence in Alaska, United States with commodity Gold

Geologic information

Identification information

Deposit ID 10002320
MRDS ID A013231
Record type Site
Current site name Amaknak Island
Related records 10258433

Geographic coordinates

Geographic coordinates: -166.55072, 53.88411 (WGS84)
Relative position Locality is 1.6 km south of Dutch Harbor airport on Amaknak Island and corresponds to locality 1 of Cobb (1972, MF-446); it is accurate to about 400 m. It also is anomaly no. 27 of Christie (1974).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Quartz Gangue

Alteration

  • (Local) Rocks are regionally propylitically altered or metamorphosed to low-grade. Area of locality is highly iron-stained. Christie (1974) reported the alteration assemblage of epidote-chlorite-kaolinite-pyrite accompanied by moderate to intense leaching.

Mineral occurrence model information

Model code 105
USGS model code 25a-d
Deposit model name Epithermal vein, generic
Mark3 model number 119

Host and associated rocks

  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Rock unit name Unalaska Formation;Unalaska Formation;Unalaska Formation
    Rock description Unalaska Formation;Unalaska Formation;Unalaska Formation
    Stratigraphic age (youngest) Miocene

Nearby scientific data

(1) -166.55072, 53.88411

Comments on the geologic information

  • Geologic Description = Christie (1974) reported a color anomaly caused by the oxidation of disseminated pyrite in volcanic breccia of the Unalaska Formation (see Drewes and others, 1961) cut by small swarms of feldspar porphyry andesite and hornblende-biotite porphyry basalt (lamprophyre) dikes. Dikes are oriented 010x dipping 80x E. The dikes are weakly mineralized, however small vuggy quartz veins occur adjacent to some dikes. Fracturing in the area varies from moderate to intense. At least one of these quartz veins was gold-bearing on the basis of a report in Drewes and others (1961).
  • Age = Miocene or younger

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Aleutians

Comments on the workings information

  • Workings / Exploration = Brief reconnaissance mapping and sampling reported by Christie (1974); however, in 1992 the entire ridge was being quarried for riprap and fill and being removed for commercial port development (F.H. Wilson, unpublished data, 1992).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013231
USGS Alaska Resource Data File ARDF UN001

Bibliographic references

  • Deposit

    Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Unalaska quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies MF-446, 1 sheet, scale 1: 250,000.

  • Deposit

    Drewes, Harold, Fraser, G.D., Snyder, G.L., and Barnett, H.F., Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-S, p. 583-676.

  • Deposit

    Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)

Comments on the references

  • Primary Reference = Christie, 1974

General comments

Subject category Comment text
Deposit Model Name = Epithermal gold vein
Deposit Other Comments = This and other undescribed occurrences were apparently reported to Drewes (Drewes and others, 1961) by someone named Eakle on the basis of local reports.

Reporter information

Type Date Name Affiliation Comment
Reporter 18-MAR-1996 L.P. Niles U.S. Geological Survey
Reporter 18-MAR-1996 S.W. Bie U.S. Geological Survey
Reporter 18-MAR-1996 Damon Bickerstaff U.S. Geological Survey
Reporter 18-MAR-1996 F.H. Wilson U.S. Geological Survey