| Basis for focus area |
The Copper Mountain focus area includes the Copper Mountain Pegmatite district – Archean rocks that are intruded by tungsten- and beryl-enriched Archean pegmatite dikes (Hausel and others, 1985; Sutherland and Cola, 2016), and an Archean "high-grade supracrustal belt" with multiple episodes of mineralization and lithologies (schists, iron formation) similar to other Wyoming greenstone belts (Hausel and others, 1985). |
| Identified resources |
Historical production of beryllium (beryl), tantalum (tantalite); minor historical production of tungsten (scheelite). |
| Production |
About 250 lbs of beryl and tantalite mined between 1928 and 1940; 300 lbs of tantalite (82% Ta2O5) was mined from the Bonneville No. 8 pegmatite in 1937 (Osterwald and others, 1966); 1980 to 1990 mined for tantalite (missing original source); few hundred tons of scheelite mined between 1942 and 1943 (Lemmon and Tweto, 1962). From Hausel and others (1985): "In 1942, a few tons of ore, averaging approximately 2% WO3, were shipped; in the following year, 40 tons of ore, averaging three percent WO3, were produced. This ore was produced from the Romur property. Production is also reported from the Whippet Mine. Three carloads of ore were shipped which averaged 1.47%, 0.16% and 2.56% WO3. |
| Status |
Past mining and exploration. |
| Estimated resources |
From Hanley and others (1950): The Whippet Prospect No. 8, the northeastern pegmatite "is estimated to contain about 11,500 tons of tantalite-bearing rock to a depth of 20 feet below the present surface. The tantalite content, based on visual estimates and past production, probably is 1 pound of tantalite in each ton of rock. The beryl in this pegmatite is confined chiefly to the lower 3 or 4 feet of the pegmatite and is visually estimated to make up 5 to 10 percent of the zone." and the southeastern pegmatite "is estimated to contain about 2,250 tons of tantalite-bearing pegmatite to a depth of 10 feet, and the tantalite content is estimated to be the same as in the northeastern pegmatite-a pound of tantalite to each ton of pegmatite. |
| Geologic maps |
Gregory and others (2010), scale 1:500,000; Love, Christiansen and Earle (1978), scale 1:250,000; Love, Christiansen, Earle and Jones (1978), scale 1:250,000; Thaden (1980a, b, c, d, e), scale 1:24,000; Hausel and others (1985), scale 1:24,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Precambrian pegmatites; pods and lenses of scheelite-bearing quartz-epidote-(clino)zoisite rock with accessory garnet (Osterwald and others, 1966) Supracrustals: schist, amphibolite, iron-formation (Hausel and others, 1985). |
| Deposits |
Whippet No. 1 (Bonneville No. 1) (MRDS dep_id: 10009181), Whippet No. 8 (Bonneville No. 8) (MRDS dep_id: 10009180), Quien Sabe (MRDS dep_id: 10181496), Comet (MRDS dep_id: 10230355), Stardust (MRDS dep_id: 10230668), Hoodoo Creek (MRDS dep_id: 10303492), Copper Mountain (MRDS dep_id: 10008888), Copper Mountain #2 (MRDS dep_id: 10157451), Riverton Mining (MRDS dep_id: 10080786), Blue Spar, Bonneville No. 3, Bonneville No. 7, Zimmerman, and numerous unnamed prospect pits, often referred to as the pegmatites near Hoodoo Creek. |
| Evidence from mineral occurrences |
MRDS. |
| Geochemical evidence |
Inferred ore reserves were 1,268 tons of 1.50% WO3 ore from scheelite (Osterwald and others, 1966, p. 199); 82% Ta2O5 tantalite ore (Osterwald and others, 1966, p. 72). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Past production for glass and ceramics, potash feldspar, tantalite, columbite, beryl in pegmatite." (Minobras, 1975, p. 31). |
| Comments |
No mining of pegmatites after 1997. Unquantified trace amounts of Cr, Mg, and V detected in McGraw mine samples, although the lithology was not disclosed (Hausel and others, 1985). Copper, Au, and Ag in several occurrences in Bridger district and supracrustals. |
| Cover thickness and description |
Pegmatites largely exposed at surface; variable thickness with respect to underground workings; igneous breccia, veins, thin coatings. |
| Authors |
Susan Hall, Robert W. Gregory, Benjamin J. Drenth, Patricia M. Webber, Rachel N. Toner. |
| New data needs |
1:24,000 scale geologic mapping supported by high-quality geophysics and lidar; Airborne EM and radiometrics could be useful especially if host rocks are shallow. |
| Geologic mapping and modeling needs |
1:24,000 scale geologic mapping; for pegmatites, any additional mapping would need to be at larger scale than 1:24,000. |
| Geophysical survey and modeling needs |
High resolution Rank 1 aeroradiometric and aeroradiometric coverage. |
| Digital elevation data needs |
Lidar complete in Wyoming. |
