Ammann

Prospect, Inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale C-1
Latitude 61.6782
Longitude -144.0671
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the divide between upper Copper Creek and an unnamed west tributary (not mapped on the C-1 quadrangle). The map site is at an elevation of 3,800 feet in the SW1/4 section 24, T. 2 S., R. 7 E., of the Copper River Meridian; it is accurately located. This prospect is adjacent to or very near the Mullen prospect (VA044) (Van Alstine and Black, 1946, plate 30). It is locality 70 of Cobb and Matson (1972) and Cobb (1979 [OFR 79-1241]) and locality 57 of Winkler and others (1981[OFR 80-892-B]).

Geologic setting

Geologic description

This copper prospect is in Triassic Chitistone limestone. This prospect was explored by two adits. The upper adit was driven S5E for 25 feet. The lower adit was driven S32W for 473 feet from the portal; there it turned and was driven 111 feet S17E (Van Alstine and Black, 1946, p. 125). At the portal and at the face of the lower adit, the limestone is cut by a few irregular veinlets less than one-quarter inch thick of malachite, azurite, and calcite (Van Alstine and Black, 1946, p. 125-126). No copper minerals are present in the upper, 25-foot-long adit, but a small, discontinuous breccia zone, 2 to 6 inches thick and 25 feet above the upper adit, contains quartz, pyrite, bornite, chalcopyrite, chalcocite, covellite, malachite, and azurite. The breccia zone strikes east-west and dips about 45 degrees south. This prospect is near the contact between Chitistone Limestone and Triassic Nikolai Greenstone. 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 (-144.069195753935, 61.6777342385967)
Mineral deposit model Vein and fracture fillings in limestone; Kennecott-type copper deposit (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 be related to Late Jurassic or Early Cretaceous deformation and metamorphism (MacKevett and others 1997, p. 88).

Production and reserves

Workings or exploration This prospect was explored by two adits. The upper adit was driven S5E for 25 feet. The lower adit was driven S32W for 473 feet from the portal, where it turned and was driven 111 feet S17E (Van Alstine and Black, 1946, p. 125).
Indication of production None

Additional comments

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

References