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Unnamed (southwest Gravina Island)

Prospect in Alaska, United States with commodities Silver, Gold, Barium-Barite
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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 10001571
MRDS ID A012321
Record type Site
Current site name Unnamed (southwest Gravina Island)

Geographic coordinates

Geographic coordinates: -131.82566, 55.1978 (WGS84)
Relative position This prospect is at sea level on the northeast shore of the unnamed cove about 0.3 mile south of Nelson Cove on southwest Gravina Island. The site is in section 15, T. 77 S., R. 88 E., of the Copper River Meridian. It corresponds to loc. 52.1 in Elliott and others (1978). The location is accurate within 0.1 mile.

Site location context

Political divisions (FIPS codes)

Ketchikan Gateway(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan A-6(quadrangle 1:63,360 scale)

Ketchikan SW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ketchikan(hydrologic unit)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Barium-Barite Critical Secondary

Comments on the commodity information

  • Gangue = Carbonate

Materials information

Materials Type of material
Barite Ore
Chalcopyrite Ore
Galena Ore
Sphalerite Ore
Quartz Gangue

Alteration

  • (Local) Local iron-staining.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -131.82566, 55.1978
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks in the general area of this prospect are complexly folded and faulted Upper Triassic carbonate, clastic, and basaltic volcanic strata (Berg, 1973; Berg and others, 1980). The deposit consists of a 3-foot-wide fault breccia in a mafic dike(?) that is structurally mixed with the Upper Triassic sedimentary and volcanic rocks. The breccia weathers orange or red, and contains quartz, carbonate, barite, and small amounts of unidentified sulfide minerals, which also are sparsely disseminated in the adjacent country rocks. Analyses of samples of the breccia and the adjacent country rocks showed up to 70 ppm Ag, 0.15 ppm Au, more than 0.5% Ba, 700 ppm Cu, 1.5% Pb, and more than 1% Zn (Koch and Elliott, 1978 [OFR 78-156A]). The analytical data indicate that the unidentified sulfide minerals probably include sphalerite, chalcopyrite, and argentiferous galena. In 1969, workings that probably date to the early 1900s consisted of an approximately 21-foot-long adit.
  • Age = The mineralized fault breccia is Late Triassic or younger.

Economic information about the deposit and operations

Development status Prospect
Commodity type Both

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = In 1969, workings that probably date to the early 1900s consisted of an approximately 21-foot-long adit. Analyses of samples of the breccia and the adjacent country rocks showed up to 70 ppm Ag, 0.15 ppm Au, more than 0.5% Ba, 700 ppm Cu, 1.5% Pb, and more than 1% Zn (Koch and Elliott, 1978 [OFR 78-156A]).

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Berg, 1973; Koch and Elliott, 1978 (OFR 78-156A)

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins? (Singer and Cox, 1986; model 22c)

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUL-99 H.C. Berg 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.