Unnamed (upper Wachusett Inlet)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu; Mo
Other commodities Ag
Ore minerals chalcopyrite; molybdenite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale D-2
Latitude 58.9549
Longitude -136.3529
Nearby scientific data Find additional scientific data near this location
Location and accuracy
This occurrence is in upper Wachusett Inlet, about 3 miles below the head of the inlet. The occurrence is on the shore line on the east side of the inlet. The location is accurate within 0.1 mile.
Most of the slope above the deposit is covered by Plateau Glacier or its morainal deposits. The occurrence is about 2 miles south-southwest of the Bruce Hills copper-molybdenum deposit (MF037). The location of the prospect is shown on an inset to figure C64 (Kimball and others, 1978). It is incorrectly located by Cobb (1972) and by MacKevett and others (1971).

Geologic setting

Geologic description

A copper-molybdenum-bearing vein cuts quartz diorite of Cretaceous age. The area is only recently free of glacial ice, and mapping is of reconnaissance type. Brew and others (1978, pl. 1A) show most of the area as granitic rock of Cretaceous age. The quartz diorite is cut by andesite and pegmatite dikes and by quartz veins.
At the prospect, which is at the shore line, a narrow quartz -sulfide vein can be traced for about 50 feet, and projected as a brecciated iron-stained vein for another 75 feet. The vein is up to 0.7 foot thick and contains about 25 percent chalcopyrite by volume. Molybdenite and pyrite are also present. Selected vein samples contain as much as 7.4 percent copper and 1500 ppm molybdenum. The vein strikes north-northeast, subparallel to the shore line, and dips steeply to the northwest.
Geologic map unit (-136.354773230177, 58.9545085189446)
Age of mineralization Cretaceous or younger.

Production and reserves

Workings or exploration The area has been explored by surface pits and trenches cut for samples. As sampled by the Bureau of Mines (Kimball and others, 1978, p. C307-C310), a chalcopyrite rich vein 0.7 foot thick contained 7.4 percent copper and 0.02 percent molybdenum. Other select samples ranged from 0.2 to 4.7 percent copper and contained from 0.03 to 0.15 percent molybdenum. Silver ranged from 5 to 30 ppm.
Indication of production None
Reserve estimates Based on the surface samples, and calculated over a 4-foot width, the occurrence is an 800-ton resource containing 0.44 percent copper, 0.05 percent molybdenum, and 0.034 ounce per ton silver (Kimball and others, 1978).

Additional comments

Area has been very recently deglaciated by recession of Plateau Glacier. The area contains other copper-molybdenum deposits and occurrences and is favorable for prospecting.
The site is within Glacier Bay National Park and Preserve.

References