Circle Cliffs Mining District, Garfield County, Utah, USAi

Regional Level Types
Circle Cliffs Mining District	Mining Region
Garfield County	County
Utah	State
USA	Country

The Circle Cliffs district, part of the Henry Mountains U mining area, is located about 27 mi east of Escalante in east-central Garfield County. The district is a modest U-V producer with a poorly documented history. The district was in production from about 1956 to 1965. Total district metal production at modern metal prices is estimated at $2.4 million. The largest operation is the Rainy Day underground mine on the east side of the district, which accounts for about 70% of the district’s production. The Horsehead and Centipede mines account for most of the rest.
The Circle Cliffs district is geologically situated in the Escalante Canyons section of the Colorado Plateau in south-central Utah. The district’s mines flank the doubly plunging, north-northwest-trending Circle Cliffs anticline. The west limb of the fold dips gently (5° to 10°) west and the eastern limb, known as the Waterpocket fold, is steeper (10° to 35°). The anticline plunges gently to the northwest and southeast. The exposed rocks range from Permian in the eroded core of the fold to Cretaceous around the rim (Doelling, 1974).
The bulk of the Circle Cliffs’ U-V ±Cu prospects and production is associated with the Upper Triassic Chinle Formation, although there are also U-V occurrences in the Upper Jurassic Morrison Formation on the east flank of the district (USGS Model 30c). The Triassic-hosted ores are primarily in basal Shinarump Conglomerate Member of the Chinle Formation channels where it has cut down into the underlying Moenkopi Formation. The Shinarump channels snake northward across the district. Mineralized rock typically ranges from 0.05% to 0.20% U3O8, 0.15% V2O5, and 0.5% to 0.3% Cu (Doelling, 1974).
Most of the deposits are small and irregular in shape, and the largest mine in the district, the Rainy Day mine, is a remarkable shoestring-shaped orebody of less than 6 square ft in cross-sectional area but mined for an extraordinary 1800 ft in length along the steep, southern Shinarump channel-fill and Moenkopi shale contact. No ore occurs in the adjoining large, open Shinarump channel despite abundant carbonaceous trash. The primary ore and sulfide minerals include uraninite, roscoelite, sphalerite, chalcopyrite, pyrite, marcasite, and galena (Davidson, 1959). Both the Rainy Day and Colt Mesa mines have the pink Co mineral erythrite. The Mo mineral ilsemannite is reported from the Rainy Day mine. In addition to U-V ±Cu, the Circle Cliffs district ores are geochemically anomalous in Ag, Co, Mo, Pb, Zn, Y, and Yb.
Much of the southern and eastern parts of the Circle Cliffs district is in Capital Reef National Park, Glen Canyon National Recreation Area, and Grand Staircase Escalante Canyons National Monument.