Bunker Hill

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu
Ore minerals azurite; bornite; chalcopyrite; covellite; malachite
Gangue minerals calcite; epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale C-1
Latitude 61.6638
Longitude -144.0184
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the east side of the upper valley of East Fork Copper Creek; it is at an elevation of 5,000 feet on the east boundary of section 30, T. 2 S., R. 8 E., of the Copper River Meridian. This prospect is approximately located, perhaps to about one-quarter mile. It is locality 73 of Cobb and Matson (1972) and is included in locality 58 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

A 25-foot-thick section of Triassic Chitistone Limestone overthrust by Triassic Nikolai Greenstone is locally cut by thin veins and veinlets containing quartz, calcite, and copper-bearing minerals (Van Alstine and Black, 1946, p. 131-132). A veinlet as much as 1 inch thick in limestone contains malachite, azurite, some bornite, chalcopyrite, calcite, and epidote. A 15-foot adit was driven along the thin veinlet in limestone. About 100 feet above the adit, a fractured zone in greenstone that structurally overlies the limestone contains several veinlets of quartz, calcite, malachite, azurite, epidote, some chalcopyrite, bornite, and covellite. This fractured zone is 6 inches to 3 feet thick, trends S30E, and dips 75 degrees southwest; it may be continuous with the mineralized zone exposed in the adit below it. The copper mineralization is believed to be related to the regional mineralizing event that produced the rich Kennecott copper deposits in the McCarthy quadrangle (MacKevett and others, 1997).
Geologic map unit (-144.020494365005, 61.66333463946)
Mineral deposit model Thin veins, impregnations, and fracture fillings in limestone and greenstone; probably related to Kennecott-type copper deposits (MacKevett and others, 1997)
Age of mineralization The copper mineralization is believed to be related to the mineralizing event that produced the rich Kennecott copper deposits in the McCarthy quadrangle to the east (MacKevett and others, 1997). This event is interpreted to have accompanied Late Jurassic or Early Cretaceous deformation and metamorphism (MacKevett and others, 1997, p. 88).
Alteration of deposit Oxidation.

Production and reserves

Workings or exploration A 15-foot-long adit was driven on a thin vein in limestone. A small open cut exposed the mineralized shear zone in overlying greenstone (Van Alstine and Black , 1946).
Indication of production None

Additional comments

This prospect is within the Wrangell-St. Elias National Park.

References