Greathouse

Prospect, Inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale HE
Quadrangle map, 1:63,360-scale A-1
Latitude 63.092
Longitude -147.395
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 5,000 feet, south of Windy Creek and about 2.6 miles east of Susitna Lodge. It is in sec.17,T. 21 S., R. 2 E., of the Fairbanks Meridian. The location is accurate to within 500 feet. The location is best shown in Kaufman (1964 GR-4, site 3) and in Smith (1981, site 28).

Geologic setting

Geologic description

The bedrock in the area of this prospect is the Triassic Nikolai Greenstone, a thick sequence of subaerial and submarine basalt flows, and minor interbedded volcaniclastic rocks, argillite, and radiolarian chert (Nokleberg and others, 1992).
The deposit consists of bornite, chalcocite, covellite, and malachite in a 3-foot-wide, northwest-trending shear zone. A chip sample across the zone contained 11% copper. The mineralized portion of the shear zone is less than 100 feet long, but the zone can be traced for more than 1,000 feet. Both the hanging wall and the footwall are altered basalt, and the brecciated country rock in the shear zone is strongly epidotized. A 4-foot-wide diorite dike cuts the basalt near the shear zone (Smith, 1981). Glavinovich (1967) noted that chalcocite replaces bornite, covellite replaces chalcocite, and quartz and malachite crosscut the sulfides. Several other northwest-trending shear zones occur in the area but are not known to contain any copper minerals. This prospect is in a broad belt of small copper occurrences that extends east-northeast for approximately 10 miles along the south side of Windy Creek.
Geologic map unit (-147.397254262616, 63.0915506156289)
Mineral deposit model Mineralized shear zone.
Age of mineralization Triassic or younger.
Alteration of deposit The country rock has been epidotized adjacent to and along the shear zone.

Production and reserves

Workings or exploration No surface workings; chip samples across a 3-foot-wide section of the shear zone contained as much as 11% Cu (Kaufman, 1964).
Indication of production None

References

MRDS Number A011361

References

Reporters D.L. Stevens (Stevens Exploration Management Corporation)
Last report date 4/7/2000