Green Butte

Mine, Inactive

Commodities and mineralogy

Main commodities Ag; Cu
Ore minerals azurite; bornite; chalcocite; covellite; malachite
Gangue minerals calcite

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale B-5
Latitude 61.4905
Longitude -142.7637
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is on the west flank of the ridge between McCarthy Creek and its east fork (MacKevett, 1974). It is at an elevation of about 4,000 feet, 1,700 feet northeast of elevation 3330 in the SW1/4 of section 30, T. 4 S., R. 15 E. of the Copper River Meridian. This is locality 87 of MacKevett (1976) and it is accurately located. Cobb and MacKevett (1980) included this mine under the name 'Green Butte'. The mine is shown on the McCarthy B-5 topographic map (1994 edition).

Geologic setting

Geologic description

The deposit at this mine consists of discontinuous vein-like bodies of chalcocite with lesser amounts of bornite, covellite, malachite, and azurite that are localized along both bedding plane and steep crosscutting faults in the basal part of the Triassic Chitistone Limestone (Miller, 1946; MacKevett, 1976). The copper minerals replace limestone and fill openings in ore bodies that are up to 4 feet thick; calcite fills openings along some steep faults. Copper mineralization is widespread in Chitistone Limestone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
The deposits were discovered about 1909 and 19 claims and 4 mill sites were patented in 1924. A total of 14,000 feet of underground workings on 8 levels including 11,000 feet of drifts, 1,500 feet of declines, and 2,500 feet of raises, winzes, and stopes, explored and developed the deposits between 1922 and 1925 (Miller, 1946). About 1,500 tons of ore containing 1,200 pounds of copper per ton and 10 ounces of silver per ton were produced between 1922 and 1925 (Miller, 1946).
Geologic map unit (-142.765777019576, 61.4900646454)
Mineral deposit model Kennecott-type copper deposit (after MacKevett and others, 1997)
Age of mineralization Cretaceous? Copper mineralization is widespread in Chitistone Limestone and is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Alteration of deposit Oxidation.

Production and reserves

Workings or exploration The deposits were discovered about 1909 and 19 claims and 4 mill sites were patented in 1924. A total of 14,000 feet of underground workings on 8 levels including 11,000 feet of drifts, 1,500 feet of declines, and 2,500 feet of raises, winzes, and stopes, explored and developed the deposits between 1922 and 1925 (Miller, 1946).
Indication of production Yes; small
Production notes About 1,500 tons of ore containing 1,200 pounds of copper per ton and 10 ounces of silver per ton were produced between 1922 and 1925 (Miller, 1946).

Additional comments

The locality is in the Wrangell-Saint Elias National Park and Preserve.

References