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Spruce Hen

Past Producer in Alaska, United States with commodities Tungsten, Molybdenum
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Geologic information

Identification information

Deposit ID 10308838
MRDS ID A015298
Record type Site
Current site name Spruce Hen
Related records 10160331, 10002826

Geographic coordinates

Geographic coordinates: -147.51995, 64.95767 (WGS84)
Relative position The Spruce Hen mine is located in the SW1/4NE1/4 sec. 34, T. 2 N., R. 1 E., Fairbanks Meridian. This prospect is located on the west side of the top of Tungsten Hill between the headwaters of Steele Creek and First Chance Creek. It is about 2.5 miles east of the junction of the Steese and Elliott Highways. This mine is included in locality 29 of Cobb (1972 [MF 410]).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Tungsten Primary
Molybdenum Secondary

Materials information

Materials Type of material
Molybdenite Ore
Scheelite Ore
Calcite Gangue
Clinozoisite Gangue
Diopside Gangue
Fluorite Gangue
Garnet Gangue
Hornblende Gangue
Vesuvianite Gangue

Alteration

  • Oxidation of scheelite in weathered zone may have occured (Byers, 1957, p. 188).

Mineral occurrence model information

Model code 42
USGS model code 14a
Deposit model name W skarn

Nearby scientific data

(1) -147.51995, 64.95767
ListMap

Comments on the geologic information

  • Geologic Description = The Spruce Hen mine is along the western contact of a large body of Cretaceous, porphyritic granite. Limestone has been replaced by scheelite, fluorite, garnet, and other typical contact-metamorphic minerals (Byers, 1957). Concentrations of scheelite were found in zones as much as 6 inches wide in blocks of fine-grained, altered igneous rock (Byers, 1957). Berg and Cobb (1967, p. 220) reported that scheelite deposits were found in tactite, silicified limestone, granite, and pegmatitic dikes and in small quartz veins in schist. In 1951, a sample of tungsten ore was submitted for testing at the metallurgical division of the Bureau of Mines (Saunders, 1958). A petrographic examination of the sample revealed it to be a contact metamorphic rock; it consists predominantly of idocrase and pyroxene, with some quartz, fluorite, garnet, wollastonite, and small amounts of scheelite, chlorite and epidote. Traces of limonite and calcite were present. This study showed that most of the scheelite is unlocked by grinding the ore to a minus 65 mesh, but grinding to minus 100 mesh was required to effect maximum liberation. By 1918, five lode prospects were being explored by trenches (Mertie, 1917). One lode was 3 to 4 feet wide, made up of schist and metamorphosed basic rock and averaged 1-2 percent scheelite with no gold. A similar lode was 4 feet wide and trended N. 33 E., with a 45 NW dip. Development work from 1916 to 1918 consisted of two shafts and many pits and trenches (Byers, 1957). An inclined shaft reportedly was sunk 70 feet on a 3-foot-thick, northwest-dipping ore body. In 1943, a pit and a trench exposed a badly weathered lode about 3 feet thick. Samples from this trench averaged 0.44percent tungsten tri-oxide (WO3). In 1957, one ton of ore was milled from this prospect (Saunders, 1958).

Economic information

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Fairbanks

Comments on the production information

  • Production Notes = One ton of ore was milled from this property (Saunders, 1958).

Comments on the workings information

  • Workings / Exploration = Development work from 1916 to 1918 consisted of two shafts and many pits and trenches (Byers, 1957). An inclined shaft reportedly was sunk 70 feet on a 3-foot-thick, northwest-dipping ore body. In 1943, a pit and a trench exposed a badly weathered lode about 3 feet thick. When visited by Saunders in 1957, two buildings remained and a headframe had been built over the shaft (Saunders, 1958).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF FB101
USGS Mineral Resources Data System MRDS A015298
USGS Mineral Resources Data System MRDS D002649

Bibliographic references

  • Deposit

    Mertie, J.B. Jr., 1917, Lode mining in the Fairbanks District, Alaska: U.S. Geological Survey Bulletin 662-H, p. 403-424.

  • Deposit

    Chapin, Theodore, 1919, Mining in the Fairbanks district: U.S. Geological Survey Bulletin 692-F, p. 321-327.

  • Deposit

    Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. Geological Survey Bulletin 712-A, p. 1-52.

  • Deposit

    Thorne, R.L., Muir, N.M., Erickson, A.W., Thomas, B. I., Hedie, H. E., and Wright, W. S., 1948, Tungsten deposits of Alaska: U.S. Bureau of Mines Report of Investigation 4174, 22 p.

  • Deposit

    Byers, F.M., Jr., 1957, Tungsten deposits in the Fairbanks district, Alaska: U.S. Geological Survey Bulletin 1024-I, p. 179-216.

  • Deposit

    Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Fairbanks quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-410, 1 sheet, scale 1:250,000.

  • Deposit

    Mulligan, J.J., 1974, Mineral resources of the Trans-Alaska Pipeline corridor: U.S. Bureau of Mines Information Circular 8626, 24 p.

  • Deposit

    Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Fairbanks quadrangle, Alaska: U.S. Geological Survey Open-File Report 76-662, 174 p.

  • Deposit

    Cobb, E.H., 1975, Mineral resources of Alaska, in Yount, M.E., ed., U.S. Geological Survey Alaska Program, 1975: U.S. Geological Survey Circular 722, p. 37.

  • Deposit

    Saunders, R.H., 1958, Work done in 1956-57 on the Spruce Hen tungsten prospect (Steele Creek): Alaska Territorial Department of Mines Prospect Evaluation 58-8, 10 p.

  • Deposit

    Smith, P.S., 1942, Mineral industry of Alaska in 1940: U.S. Geological Survey Bulletin 933-A, p. 1-102.

  • Deposit

    Thorne, R.L., Muir, N.M., Erickson, A.W., Thomas, B. I., Hedie, H. E., and Wright, W. S., 1948, Tungsten deposits of Alaska: U.S. Bureau of Mines Report of Investigation 4174, 51 p.

Comments on the references

  • Primary Reference = Byers, 1957

General comments

Subject category Comment text
Deposit Model Name = W skarn deposit (Cox and Singer, 1986; model 14a)

Reporter information

Type Date Name Affiliation Comment
Reporter 31-JUL-2001 J.R. Guidetti Schaefer and C.J. Freeman Avalon Development Corporation