Westover

Mine, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Ag; As
Ore minerals bornite; chalcocite; chalcopyrite; malachite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale MC
Quadrangle map, 1:63,360-scale B-4
Latitude 61.3967
Longitude -142.4967
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is at the head of Boulder Creek, a north tributary to Dan Creek (MacKevett and Smith, 1972). It is at an elevation of about 4,750 feet just inside the west boundary of the McCarthy B-4 quadrangle, in the NW1/4 of section 35, T. 5 S., R. 16 E. of the Copper River Meridian. This is locality 72 of MacKevett (1976); the location is accurate within a few hundred feet. Cobb and MacKevett (1980) include this mine under the name 'Westover'.

Geologic setting

Geologic description

This deposits consists of bornite and less abundant chalcocite in replacement lenses to 40 feet wide along beds in the lower part of the Triassic Chitistone Limestone. Oxidation of the copper sulfides has produced malachite and some sparse chalcopyrite has been observed (Miller, 1946). Channel samples across the mineralization contained 50 parts per million (ppm) silver, 2,000 ppm arsenic, and more than 2 percent copper (MacKevett and Smith, 1968). The bornite-rich replacements are mainly localized along small bedding-plane faults, but some mineralization is also localized along small steep faults. Calcite and quartz commonly are gangue minerals and some sulfide bodies grade laterally into silicified limestone. Copper mineralization in the Chitistone Limestone is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
This mine, first staked about 1906, was developed by 1,400 feet of underground workings on four unconnected levels (Miller, 1946, p. 108-110). Some ore was shipped in the winter of 1917-18, and in 1943 an estimated 100 tons of material grading 30 percent copper and another 100 tons of material grading 10 per cent copper were exposed in the workings (Miller, 1946).
Geologic map unit (-142.49875703266, 61.3962714317313)
Mineral deposit model Kennecott-type copper deposit? (after MacKevett and others, 1997).
Age of mineralization Cretaceous? Copper mineralization in the Chitistone Limestone 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 of copper sulfides; silicification of limestone.

Production and reserves

Workings or exploration This mine was first staked about 1906, was developed by 1,400 feet of underground workings on four unconnected levels, and produced a small amount of bornite-rich ore in the winter of 1917-18 (Miller, 1946, p. 108-110).
Indication of production Yes; small
Reserve estimates In 1943 an estimated 100 tons of material grading 30 percent copper and another 100 tons of material grading 10 per cent copper were exposed in the workings (Miller, 1946).
Production notes Some ore was shipped in the winter of 1917-18 (Miller, 1946).

Additional comments

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

References