Unnamed (west of Powell Gulch northeast of peak 5950)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Au
Ore minerals chalcopyrite; hematite; pyrite
Gangue minerals chlorite; epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-2
Latitude 63.1549
Longitude -144.8574
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is near the top of the ridge south of Slate Creek and west of Powell Gulch. It is a few hundred feet northeast of peak 5950. The occurrence is in the SW1/4NW1/4 section 27, T. 20 S., R. 15 E., Fairbanks Meridian. It corresponds to locality 27 of Rose (1967), locality 19 on figure 6 of Cobb (1979 [OFR 79-239]), and locality 137 in table 2 of Nokleberg and others (1991). The location is accurate within 0.1 mile.

Geologic setting

Geologic description

The rocks near peak 5950 are mainly Tetelna Volcanics of Pennsylvanian age (Richter and Dutro, 1975), previously mapped as Chisna Formation of Pennsylvanian and Permian (?) age (Rose, 1967). Intrusions of quartz monzonite and the Gakona diorite of Mesozoic age occur in the vicinity. Locally, the volcanic rocks contain secondary epidote and have been chloritized and pyritized and contain disseminated chalcopyrite.
Nokleberg and others (1991, table 2) collected a grab sample from a zone about 10 feet wide and 30 feet long that assayed 1.4 percent copper and 15 parts per million silver. A select sample from a chalcopyrite-bearing boulder assayed a trace of gold, 0.52 ounce of silver per ton and 1.14 percent copper (Rose, 1967).
Geologic map unit (-144.859625898259, 63.1545018657047)
Mineral deposit model Cu skarn or Porphyry Cu, distal (Cox and Singer, 1986; model 18B or 20c).
Mineral deposit model number 18b or 20c
Age of mineralization Probably Mesozoic, related to nearby intrusions of quartz monzonite and Gakona diorite (Rose, 1967).
Alteration of deposit Sulfidization of Pennsylvanian volcanic rocks; introduction of chlorite and epidote.

Production and reserves

Workings or exploration Limited surface sampling.
Indication of production None