West Twin Peak

Occurrence in Alaska, United States with commodity Chromium
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 10000970
MRDS ID A011642
Record type Site
Current site name West Twin Peak
Alternate or previous names West Ridge, Eklutna Creek
Related records 10233800

Geographic coordinates

Geographic coordinates: -149.23265, 61.44955 (WGS84)
Relative position On ridge 2 miles west of West Twin Peak summit, at 2,500 ft elevation. Accurate within 1,000 ft. Locality 41 of Cobb (1972) and locality 31 of MacKevett and Holloway (1977).

Site location context

Political divisions (FIPS codes)

Anchorage(Municipality)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Anchorage B-6(quadrangle 1:63,360 scale)

Anchorage SW(quadrangle 1:100,000 scale)

Anchorage(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Matanuska(hydrologic unit)

Knik Arm(hydrologic accounting unit)

South Central Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

BLM(Federal land areas administered by BLM)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Chromium Critical Primary

Materials information

Materials Type of material
Chromite Ore

Alteration

  • (Local) Slight serpentinization of olivine.

Mineral occurrence model information

Model code 15
USGS model code 8a
Deposit model name Podiform chromite (minor)
Mark3 model number none
Model code 23
USGS model code 9
Deposit model name Alaskan Cr-Pt (PGE)
Mark3 model number 120

Nearby scientific data

(1) -149.23265, 61.44955

Economic information

Comments on the geologic information

  • Geologic Description = Chromite-rich dunite of the Jurassic Eklutna Sequence containing bands of chromite up to 1 inch thick found in a zone 10 ft thick. Chromite-rich rock could be traced for about 30 ft before it was covered by talus. Chip samples across a 10 ft zone contained 7.93 percent chromite (Rose, 1966).
  • Age = Lower to Middle Jurassic

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Anchorage

Comments on the workings information

  • Workings / Exploration = Chip samples across a 10 ft zone contained 7.93 percent chromite, with a Cr:Fe ratio of 2:1 (Rose, 1966). Pieces of float containing about 90 percent chromite as large as 4 inches in diameter are found on site.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Rose, 1966

General comments

Subject category Comment text
Deposit Model Name = Podiform chromite or Alaskan PGE (Cox and Singer, 1986; models 8a or 9)
Deposit Other Comments = Unconfirmed report of the presence of tin ore (Brooks, 1918). Some confusion exists about the name of this locality. Cobb (1972, loc. 41) refers to it as Eklutna Creek, while others refer to it as West Twin Peak.

Reporter information

Type Date Name Affiliation Comment
Reporter 30-JUL-1998 D.P. Bickerstaff U.S. Geological Survey
Reporter 30-JUL-1998 S.W. Huss U.S. Geological Survey

Beyond USGS

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

Authoritative Alaska resources

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