Von Gruenther

Prospect, Inactive

Alternative names

Malack

Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite; malachite; pyrite
Gangue minerals epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale B-2
Latitude 60.4603
Longitude -147.6738
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located in the SW1/4 section 2, T. 4 N., R. 10 E., of the Seward Meridian. It is located on the south end of Louis Bay, 4 to 15 feet above sea level. This is location 198 of Tysdal (1978 [MF-880-A]) and location S-82 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The prospect consists of three shear zones that strike N 50 E and dip 65-75 S. The shear zones cut greenstone and are cemented by quartz-epidote-sulfide veins (Kurtak and Jeske, 1986). The greenstone is part of the Orca Group of early Tertiary age (Nelson and others, 1985). Two 10-foot-long adits are driven on two of the shear zones, which are about 20 feet apart. An 14-foot-long open cut follows the third shear zone.
The southernmost adit follows a 2- to 8-inch-wide quartz vein for 15 feet. The vein contains epidote, pyrite, and a small amount of chalcopyrite. The north adit follows a 6- to 8-inch-wide breccia zone for 12 feet. It contains chalcopyrite, malachite, and pyrite. The open cut exposes a 6-inch-wide breccia zone that is cemented by quartz, pyrite, and chalcopyrite. The hanging wall of this zone is silicified for about 2 feet. Random chip samples collected from the adits and surface exposures contained from 200 ppm to 1.9 percent copper and from 0.3 to 6.3 ppm silver. The random chip sample containing 1.9 percent copper was from greenstone breccia with quartz epidote veins and visible chalcopyrite and a trace of malachite. (Kurtak and Jeske, 1986).
Geologic map unit (-147.675799032408, 60.4596968150887)
Mineral deposit model Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number 24a
Age of mineralization Tertiary or younger; the mineralization is in rocks of the Orca Group of Tertiary age.
Alteration of deposit Silicification and epidotization are reported, but no details are provided (Kurtak and Jeske, 1986).

Production and reserves

Workings or exploration Workings on the prospect consist of two 10-foot adits and a 14-foot open cut. Samples collected from the adits and the open cut by the U.S. Bureau of Mines contained between 200 ppm and 1.9 percent copper. The random chip sample containing 1.9 percent copper was from greenstone breccia with quartz epidote veins and visible chalcopyrite with a trace of malachite (Kurtak and Jeske, 1986).
Indication of production None

References

References

Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 12/15/2000