Stratabound copper-silver-bearing oolitic deposits in the Belt Supergroup of Montana

Mineral resources of the Sleeping Giant Wilderness Study Area, Lewis and Clark County, Montana

“…Locality 5 represents mineralized green siltite (metamorphosed siltstone, with minor limestone). Mineralized rocks were reported west and south of the study area (Lange and Eby, 1981;Lange and others, 1986;Lange and others, 1987) and were found to extend into the area during the present study. Several other green siltite units that contain minor copper and silver were also examined.…”

“…In November, 1976, Harvey B. Straude located a claim over the north canyon wall of Spring Gulch west of the study area, where copper-bearing green siltites crop out. In June, 1977, Ed and Robert Leo Zitnik and Kenneth and Edward Schmaus located claims west of the study area covering parts of the mineralized rock reported by Lange and Eby (1981). It is not certain who excavated a shallow 4-ft-wide by 4-ft-long pit in green siltite at the head of Bear Gulch in the western part of the study area (loc.…”

“…Mineralized green beds are present in nearly all formations of the Belt Supergroup in western Montana (Harrison, 1972(Harrison, , 1974, but carbonate-host rocks are known only in the Helena or Wallace Formations (Harrison, 1972(Harrison, , 1974 and in limestone to calcareous siltstone of the Spokane Formation (Lange and Eby, 1981;Lange and Sherry, 1986;Lange and others, 1987). The Helena or Wallace Formations are not present in the vicinity of the study area, but the Spokane Formation crops out in and adjacent to the western part of the study area and contains both green bed-and carbonate-hosted mineralized rock.…”

“…Mineralized carbonate rocks of the Helena Formation at Red Mountain, north of Lincoln ( fig. 1), also are oolitic (Lange and Eby, 1981).…”

Mineral resources of the Quigg West Wilderness Study Area, Granite County, Montana

“…No strata of this association were seen in the study area, although there is a slight possibility that such strata could be present, but unobserved. The carbonate-hosted copper-silver sulfide minerals occur in carbonate strata of the Helena Formation (Harrison, 1972(Harrison, , 1974 and in limestone to calcareous siltstone of the Middle Proterozoic Spokane Formation of the Ravalli Group of the Belt (Lange and Eby, 1981;Lange and Sherry, 1986;Lange and others, 1987). The Helena Formation crops out in the general region of the study area (in the southern part of the region shown on fig.…”