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Pumicestone Bay

Prospect in Alaska, United States with commodities Gold, Silver, Lead, Barium-Barite, Zinc
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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 10003259
MRDS ID A106001
Record type Site
Current site name Pumicestone Bay

Geographic coordinates

Geographic coordinates: -166.96016, 53.51854 (WGS84)
Relative position South of the head of Pumicestone Bay, on south side of river entering bay from the southwest. Anomaly 41 of Christie (1974).

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

St. George Tanaq Corporation(ANCSA Village)

ANCSA Village NTVPIC(Type of land area)

NTVPIC(Federal land areas administered by NTVPIC)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Primary
Lead Secondary
Barium-Barite Critical Secondary
Zinc Critical Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Pyrite Ore
Sphalerite Ore
Chlorite Gangue
Epidote Gangue
Magnetite Gangue
Specularite Gangue

Alteration

  • (Local) Rocks are regionally propylitically altered and also hornfelsed as a result of proximity to the Shaler batholith (Simpson, 1986). Highest gold grades are associated with zones of 'pyrite-silica' alteration in 'spotted andesite' (Simpson, 1986).

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46
Model code 105
USGS model code 25a-d
Deposit model name Epithermal vein, generic
Mark3 model number 119

Nearby scientific data

(1) -166.96016, 53.51854
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Christie (1974) reported a single 3,000 ft (900 m) by 1,500 ft (450 m) color anomaly whereas later evaluations by Randolph and Ellis (1989) and Randolph (1991) described three color anomalies aligned along a steep valley wall. Country rock is the Unalaska Formation (see Drewes and others, 1961), near a sheared contact with the Shaler batholith. Granodiorite of the pluton occurs below the color anomalies at elevations below about 600 feet (200 m). Prospect lies at contact with metamorphosed impure sandstone, breccia, and quartz pebble conglomerate. Stockwork veining and silicification is locally developed within an exposed volume of 1600 by 160 feet, having a 75 foot thickness (80 x 50 x 20 m). Semi-parallel northeast-trending shear zones cut off the quartz stockwork and silicification to the northwest. Quartz veining occurs parallel and/or marginal to these shear zones. Largest of these quartz veins is about 1 foot (30 cm) wide, gossanous, and contains up to 20 percent pyrite (Randolph, 1991) and rare chalcopyrite, sphalerite, and/or galena (Christie, 1974; Randolph, 1991). Randolph's (1991) interpretation was that there were two episodes of veining, where the sulfide-bearing shear-hosted veins cut the earlier quartz stockwork.
  • Age = Miocene or younger

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Aleutians

Comments on the workings information

  • Workings / Exploration = Battle Mountain Exploration Co. (BMEC) established a sampling grid over one exposure of hornfelsed volcaniclastic rocks and/or graywacke that has been strongly stockworked and silicified. Quartz stringer densities were as high as 2 per inch (2.54 cm) and only rarely contain visible sulfides. The quartz stockwork contained gold to 272 ppb and slightly anomalous lead and barium. Quartz veins hosted in the northeast-trending shear zones contain up to 275 ppb gold, 31.5 ppm silver, 0.24 percent lead, 0.14 percent zinc, elevated barium and insignificant mercury and arsenic (Randolph, 1991).

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.)

  • Deposit

    Randolph, D.B., and Ellis, W.T., 1989, Unalaska project, 1989 final report: Battle Mountain Exploration Company, Alaska District, 41 p., 5 appendices, 11 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)

  • Deposit

    Randolph, D.B., 1991, Unalaska project, 1990 final report: Battle Mountain Exploration Company, Alaska District, 62 p., 5 appendices, 15 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)

  • 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 = Randolph, 1991

General comments

Subject category Comment text
Deposit Model Name = Polymetallic vein, epithermal gold vein
Deposit Model Number = 22c, 25
Deposit Other Comments = Randolph (1991) gave the prospect a poor potential for economic gold mineralization due to remoteness, ruggedness of the environment, and minimal evidence for economic mineralization.

Reporter information

Type Date Name Affiliation Comment
Reporter 06-MAY-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.