Walsh Cut (Rock Creek)

Mine, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Pb; Sb; W
Ore minerals arsenopyrite; galena; pyrite; scheelite; scorodite; stibnite
Gangue minerals albite; calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-1
Latitude 64.6118
Longitude -165.4148
Nearby scientific data Find additional scientific data near this location
Location and accuracy This small lode and placer mine is on the east slope of Rock Creek valley at an elevation of about 350 feet and about 4,000 feet due east of the Snake River road. The map loction is in the north-central part of section 23, T. 10 S., R. 34 W., Kateel River Meridian. Hummel (1962 [MF 247, locality 7]) mistakenly called this location Sophie. Sophie Gulch is about 600 feet northwest of the Walsh Cut. This mine is located to within about 250 feet.

Geologic setting

Geologic description

A hydraulic pit dating originally from before 1920 mined a residual placer developed on complex gold-arsenic deposits on the side hill above and southeast of Sophie Gulch. A narrow and irregular zone of northeast-trending sheeted quartz veins, subparallel to those of the Rock Creek deposit (NM207), underlies part of the pit. The pit walls also expose early arsenopyrite-albite zones localized by northwest-trending faults (?) and by nearly recumbent isoclinal folds whose axes trend northwest. The general northeasterly trend of the sheeted veins was explored by Placer Dome in 1987 and 1988 for a total strike distance of about 1,000 feet northeast from the hydraulic pit. Placer Dome and Kennecott Exploration Company also explored southwest from the pit. Additional sheeted veins were found, but they did not appear to be continuous with those northeast of Walsh Cut.
It appears that residual material mined in the pit was concentrated in a sluice box at the downslope end of the pit. The process was inefficient and low-grade alluvial fan deposits formed below the hydraulic operation (NM215). Material in the fan deposits indicates that arsenopyrite, partly oxidized to scorodite, was abundant in the residual deposit. Galena and stibnite have also been found in quartz below the hydraulic pit. Scheelite was probably recovered in the sluice operation.
Geologic map unit (-165.417407507862, 64.6110346151152)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Mid-Cretaceous; veins cross cut regionally metamorphosed schist; see NM207.
Alteration of deposit Albitization.

Production and reserves

Workings or exploration
The character of the tailings indicates that there were at least two episodes of placer mining, one pre-1920 and the other possibly after World War II. Sheeted quartz veins projected northeast and southwest of the pit were explored by Placer Dome in 1987 and 1988 and by Kennecott Exploration Company in 1994. The locality was visited and mapped by Newmont Mining Company in about 1991 or 1992.
At least 15 holes have been drilled to explore the sheeted vein trend northeast of the pit; in approximate southwest to northeast order, these include Placer Dome reverse circulation holes 88-077 and 083; 88-051, -052, and -067; 88-068, -069, and -070; 88-071, -073, and -074; and 88-089. Placer Dome drilled one core hole (88-039) in the drill fence with 071, 073, and 074. Newmont drilled one core hole adjacent to Placer Dome 88-068.
Indication of production Yes; small
Production notes Small production of gold and probably some scheelite by hydraulic methods.