Mount Vesta

Prospect, Probably inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb
Other commodities Bi; Sb
Ore minerals chalcopyrite; galena; malachite; sphalerite; tetrahedrite
Gangue minerals calcite

Geographic location

Quadrangle map, 1:250,000-scale DE
Quadrangle map, 1:63,360-scale D-3
Latitude 54.9254
Longitude -132.9466
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 720 feet about 0.6 mile west-southwest of the head of Vesta Bay. It is near the northwest corner of section 20, T. 80 S., R. 83 E. The location is probably on the four patented mining claim shown on current (2003) U.S. Forest Service maps. The location is accurate to within one-quarter mile.

Geologic setting

Geologic description

The Mount Vesta prospect was found before 1902 and was explored intermittently until at least 1906 by several open cuts and an adit 89 feet long (Brooks, 1902; Wright and Wright, 1905, 1906, 1908; Smith 1914). The rocks in the vicinity consist of pre-Ordovician marble to the west of a regionally-extensive normal fault, and mixed pre-Ordovician marble and metamorphosed dacitic rocks to the east of the fault (Gehrels, 1991). It is unclear which side of the fault the Mount Vesta prospect is on, but the host rocks at the prospect are mainly marble cut by a mafic dike.
Maas and others (1991) mapped an 89-foot adit that follows an S-shaped vein 0.17 to 0.33 feet wide that has tetrahedrite, malachite, and calcite near the portal. Samples contained up to 25.95 ounces of silver per ton, 1.2 percent copper, 3.34 percent lead, 1.14 parts per million (ppm) gold, and more than 2,000 ppm bismuth and antimony. Other mineralized zones may be present. Wright and Wright (1906) mention the occurrence of chalcopyrite, galena, and sphalerite.
Geologic map unit (-132.948259461249, 54.9250534491103)
Mineral deposit model Shear zone cuts marble and contains tetrahedrite, chalcopyrite, galena, and sphalerite.
Age of mineralization Unknown, other than that the prospect is younger than the pre-Ordovician host rocks.
Alteration of deposit Oxidization of copper minerals.

Production and reserves

Workings or exploration Developed by open cuts and an 89-foot adit by 1906. Probably no substantial work since.
Indication of production None

Additional comments

Located on four patented mining claims. The adjacent lands in the area have been conveyed to the Sealaska Corporation or are under application.


MRDS Number A010263


Reporters D.J. Grybeck (Applied Geology)
Last report date 9/1/2003