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Eldorado

Past Producer in Alaska, United States with commodity 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 10000941
MRDS ID A011612
Record type Site
Current site name Eldorado
Alternate or previous names Alaska Free Gold Mining Co.

Geographic coordinates

Geographic coordinates: -149.29268, 61.7815 (WGS84)
Relative position Marked with an adit symbol and labeled 'Eldorado Mine' on the Anchorage D-7 1:63,360-scale topographic map, on eastern flank of Skyscraper Mountain - north of Hatcher Pass. Accurate within 400 ft.

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

Materials information

Materials Type of material
Gold Ore
Quartz Gangue

Alteration

  • (Local) The vein and host are oxidized to depths of 30 ft (Capps, 1915). 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) -149.29268, 61.7815
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Capps (1915) reported a 1 to 18 inch wide gougy quartz vein cuts the Late Cretaceous Willow Creek Pluton. The quartz vein strikes N 24 W, and dips 36 W, and consists of solid quartz, associated with some clayey gouge. 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. The vein and host are oxidized to depths of 30 ft (Capps, 1915). 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 = A few tons milled in 1911, about 100 tons milled in 1912 (Capps, 1915). Undetermined amount of ore trammed to the mill in 1939 and 1940.

Comments on the workings information

  • Workings / Exploration = Developed by several large open cuts and an inclined 30 ft adit. In 1911 a few tons of ore from the property was milled in the mill of the Alaska Gold Quartz Mining Co., (the Independence mine - ARDF number AN001) and yielded the first gold produced from this mine. Reportedly in 1912 about 100 tons of ore was dragged down a trail to a point from which it could be trammed to the mill (Capps, 1915). Stoll (1997) indicated that in the summer of 1939 the old shaft was reopened and retimbered by Alaska Pacific Consolidated Mining Co., and shipments of near-surface quartz were sent down to the old mill. In July the following summer the shaft was deepened, staying beneath the Eldorado vein. A raise to the vein and a drift northward along it were driven, finding ore with gold values good enough for the mill. By the summer of 1941 further exploration at Eldorado was 'outranked' by other ore-hunting plans.

Reference information

Bibliographic references

  • Deposit

    Capps, S.R., 1915, The Willow Creek District, Alaska: U.S. Geological Survey Bulletin 607, 86 p.

  • Deposit

    MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.

  • Deposit

    Stoll, W.M., 1997, Hunting for gold in Alaska's Talkeetna Mountains 1897-1951: Greensburg, Pennsylvania, Henry Printing, 301 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Anchorage quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-409, 1 sheet, scale 1:250,000.

  • Deposit

    MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous mineral deposits in the western part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, 38 p., 1 sheet, scale 1:1,000,000.

  • Deposit

    Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials in the Anchorage quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1095, 184 p.

Comments on the references

  • Primary Reference = Capps, 1915

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.