Cascade

Mine, Probably inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Pb
Ore minerals arsenopyrite; chalcopyrite; galena; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PE
Quadrangle map, 1:63,360-scale D-3
Latitude 56.9897
Longitude -132.7938
Nearby scientific data Find additional scientific data near this location
Location and accuracy This small mine can be been in outcrop just above the high-tide level on the eastern shoreline of Thomas Bay. It is near an unnamed point about 0.6 mile south of Spray Island in the NW1/4, section 25, T. 56 S., R. 79 E. The location is accurate.

Geologic setting

Geologic description

Buddington (1923) described this deposit as a quartz vein that can be traced for about 250 feet. It consists of a sheeted zone at least 12 feet thick; about half of the sheeted zone is milky-white quartz and half schist. The property was active intermittently until at least into the 1940s. In 1949, 6 tons of ore was mined that produced 6 ounces of gold and 1 ounce of silver. The quartz veins contain sparse, disseminated pyrite, arsenopyrite, chalcopyrite, pyrrhotite, and galena; specimens of arsenopyrite several inches across are common on the dump. The workings are less than 200 feet from the shore line and include two short adits, one 21 feet long and the other 71 feet long, and a trench. The rocks in the area consist of biotite schist and gneiss, gneissic granodiorite, and quartz monzodiorite (Brew and others, 1984).
Maas and Redman (1989) mapped and sampled the workings. One of their samples of a 4-inch-wide quartz vein contained 6,975 parts per billion (ppb) gold; their other 7 samples averaged 371 ppb gold. Still and others (2002) examined the property in 1998. They sampled the mineralized zones which are 3.5 to 6 feet thick. Their highest grade sample across 3.5 feet of vein contained 589 ppb gold but the average of their 8 samples was 137 ppb gold.
Geologic map unit (-132.795516420987, 56.9893620929504)
Mineral deposit model Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger based on the age of the metamorphic host rock.
Alteration of deposit Unknown or minor.

Production and reserves

Workings or exploration There was some minor development on the prospect prior to 1921. The property was active intermittently until at least into the 1940s. A claim was active as recently as 1979.
Indication of production None
Production notes In 1949, 6 tons of ore was mined that produced 6 ounces of gold and 1 ounce of silver.

References

MRDS Number A010338

References

Maas, K.M., and Redman, E.C., 1989, Notes and sketch map of Cascade Mine: Unpublished report by the U.S. Bureau of Mines, 1 sheet, 3 p. (On file at the Bureau of Land Management, Minerals Information Center, Juneau, Alaska.)
Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002, Mineral assessment of the Stikine area, central Southeast Alaska: U.S. Bureau of Land Management Technical Report 51, 560 p.
U.S. Bureau of Mines, 1980, Claim map, Petersburg quadrangle, Alaska: U.S. Bureau of Mines Map 117, 1 sheet, scale 1:250,000.
Reporters D.J. Grybeck (Port Ludlow, WA)
Last report date 4/8/2007