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Marion Twin

Past Producer in Alaska, United States with commodities Gold, Copper, Lead
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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 10000944
MRDS ID A011615
Record type Site
Current site name Marion Twin
Related records 10161552

Geographic coordinates

Geographic coordinates: -149.30158, 61.8115 (WGS84)
Relative position 2,000 ft east-northeast of the end of the unimproved road that parallels to Craigie Creek. Marked with quarry symbol and labeled 'Marion Twin Mine' on the Anchorage D-7 1:63,360-scale topographic map. Accurate within 400 ft. Locality 15 of Cobb (1972) and locality 12 of MacKevett and Holloway (1977).

Site location context

Political divisions (FIPS codes)

Matanuska-Susitna(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Anchorage D-7(quadrangle 1:63,360 scale)

Anchorage NW(quadrangle 1:100,000 scale)

Anchorage(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Lower Susitna River(hydrologic unit)

Susitna River(hydrologic accounting unit)

South Central Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Copper Secondary
Lead Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Gold Ore
Quartz Gangue

Alteration

  • (Local) Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954).

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Nearby scientific data

(1) -149.30158, 61.8115
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Quartz vein, 2 to 10 inches thick, cuts quartz diorite of the Late Cretaceous Willow Creek Pluton. The thin, gently NW dipping quartz vein is in a shear zone and contains free gold, pyrite, galena, and chalcopyrite. The vein has been broken by post-mineralization faulting. The ore plays out where vein rolls upward into a shear zone, south of the mine (Ray, 1954).? the Willow Creek Pluton is a zoned pluton: the outer part consists of hornblende quartz diorite and lesser hornblende tonalite; the core consists of hornblende-biotite granodiorite, and lesser hornblende-biotite quartz monzodiorite and biotite quartz monzonite. Wall-rock alteration within a few inches of the veins is intense, but seldom extends more than 10 to 12 inches beyond the quartz filling. Sericitization and carbonate alteration predominate, but there is some pyritization and in the outer parts of the alteration zone chloritization is present (Ray, 1954).
  • Age = Late Cretaceous or younger; vein cuts the Late Cretaceous Willow Creek Pluton.

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Willow Creek

Comments on the production information

  • Production Notes = Capps and Tuck (1935) reported that in 1929 and 1930 a few tons of rich ore was mined; some ore was sent to a smelter and some ore was sent to the company's mill on the Little Susitna River (at Lonesome Mine ARDF number AN063). Last production was reported in 1935.

Comments on the workings information

  • Workings / Exploration = The extent of the mine was an open cut about 50 ft x 30 ft.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Ray, 1954

General comments

Subject category Comment text
Deposit Model Name = Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)

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.

External references

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.