Unnamed (east of Waterfall Lake)

Occurrence, Undetermined

Commodities and mineralogy

Main commodities Cu
Ore minerals malachite
Gangue minerals epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale C-6
Latitude 57.5325
Longitude -135.8158
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 1,000 feet, about 1.8 miles east of the outlet of Waterfall Lake. The occurrence is 0.2 mile southeast of the center of sec. 17, T. 50 S., R. 60 E. It is location 43 of Cobb (1972, 1978). The location probably is accurate within 0.2 mile.

Geologic setting

Geologic description

Johnson and Karl (1985) map the rocks in the area of this occurrence as Triassic(?) greenstone that is intruded by a northwest-striking, linear sill(s) of Cretaceous(?) diorite. The rocks are cut by steeply-dipping, mainly northwest-striking faults; these include the regional-scale Border Ranges Fault whose trace is just southwest of the occurrence. The fault apparently is intruded by the sill(s).
Cobb (1972, 1978), citing Loney and others (1963), describes the occurrence as secondary copper minerals in quartz and epidote amygdules in greenstone. Triassic(?) greenstone elsewhere on northwest Chichagof Island generally contains primary copper minerals that are about the same age as the greenstone host rock (see, for example, SI035 and SI036).
Geologic map unit (-135.817604624517, 57.5321424240164)
Mineral deposit model Basaltic copper (Cox and Singer, 1986; model 23).
Mineral deposit model number 23
Age of mineralization Triassic(?) greenstone elsewhere on northwest Chichagof Island generally contains primary copper minerals that are about the same age as the greenstone host rock.

Production and reserves

Indication of production None

Additional comments

The occurrence is in West Chichagof-Yakobi Wilderness.

References