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Tarasof Point

Occurrence in Alaska, United States with commodities Molybdenum, Copper, Silver, Gold
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10003279
MRDS ID A106021
Record type Site
Current site name Tarasof Point

Geographic coordinates

Geographic coordinates: -166.93572, 53.68243 (WGS84)
Relative position West side of Anderson Bay, 2 miles (3.2 km) southwest of Tarasof Point. Anomaly no. 20 of Christie (1974). Anderson Bay is the south arm of Makushin Bay.

Site location context

Political divisions (FIPS codes)

Aleutians West(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Unalaska B-3(quadrangle 1:63,360 scale)

Unalaska NW(quadrangle 1:100,000 scale)

Unalaska SE(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Fox Islands(hydrologic unit)

Aleutian Islands(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Alaska Maritime National Wildlife Refuge(National Wildlife Refuge)

National Wildlife Refuge FWS(Type of land area)

FWS(Federal land areas administered by FWS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Molybdenum Primary
Copper Primary
Silver Primary
Gold Primary

Materials information

Materials Type of material
Pyrite Ore
Chlorite Gangue
Epidote Gangue
Limonite Gangue

Alteration

  • (Local) The core of the occurrence shows intense silicification and on the periphery, the development of chlorite and epidote indicate propylitic alteration. Leaching is complete in the area of interest.

Mineral occurrence model information

Model code 53
USGS model code 17
Deposit model name Porphyry Cu
Mark3 model number 4
Model code 105
USGS model code 25a-d
Deposit model name Epithermal vein, generic
Mark3 model number 119

Nearby scientific data

(1) -166.93572, 53.68243
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The occurrence is defined by multiple color anomalies surrounding breccia pipes emplaced through a pendant(?) of volcanic rocks of the Unalaska Formation (see Drewes and others, 1961) between exposures of diorite plutons. The color anomalies occur in two 1,000 ft (300 m) by 3,000 ft (915 m) areas. Late mineral quartz-feldspar porphyry and crowded feldspar porphyry dikes cut the breccia pipes. The breccia pipes may have originally contained up to 15 to 20 percent sulfides, which are now totally leached. Copper may have been present, as traces of chalcopyrite occur in the adjacent diorite plutons. Alteration and the amount of pyrite appear to decrease abruptly away from areas of breccia. According to Christie (1974), fracturing is very important (in localizing alteration?). Within the breccia pipes, there is intense silicification and peripheral to this, secondary chlorite and epidote are developed. The occurrence is capped by highly altered rocks distinguished by the development of limonite.
  • Age = Cenozoic

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 = Reconnaissance mapping and multiple soil samples were used to evaluate the color anomaly. Samples showed up to 260 ppm copper, 28 ppm molybdenum, 2.6 ppm silver, and 0.24 ppm gold.

Reference information

Bibliographic references

  • 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 = Copper porphyry, epithermal gold vein
Deposit Model Number = 17, 25
Deposit Other Comments = the mode of occurrence suggests an epithermal gold vein model should be considered as a possible model for this system.

Reporter information

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

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.