Greasewood Draw Mining District, Emery County, Utah, USAi

Regional Level Types
Greasewood Draw Mining District	Mining District
Emery County	County
Utah	State
USA	Country

The Greasewood Draw mining district of the San Rafael Swell U mining area is located 16 mi west of Green River in east-central Emery County. Mineralization was initially discovered in the mid-1950s and the district became an insignificant U-V producer. All the mines are small, but the largest producers were the Black Dragon, Uneva, and Cliff Dweller.
Greasewood Draw is geologically situated on the east flank of the San Rafael Swell of the Colorado Plateau. The Swell is an asymmetric, doubly plunging anticline, having a steeply dipping east limb. Mineralization in the San Rafael Swell district is predominantly hosted in the Upper Triassic Chinle Formation. The Chinle consists of three fining-upward, fluvial-lacustrine sandstone sequences. Sedimentological work on the Chinle suggests northwest-trending transport from a braided-stream environment in the southeast to floodplain and lacustrine environments progressively to the northwest.
The U ±V ores of the district are hosted in the moderately east-dipping (10° to 60°) Upper Triassic Chinle Formation (USGS Model 30c). The major host is the Moss Back Member, but U prospects are also found in the Temple Mountain and Monitor Butte Members. Orebodies in the Moss Back Member are hosted in tabular sandstones and conglomerates, typically within 40 ft of the base of the member and orebodies are typically less than 2000 tons. The principal ore minerals are uraninite and uranophane interstitial to sand grains and associated with bleaching. In addition to U-V, the ores may also be anomalous in As, Cu, and Mo (Mickle and others, 1977; Gloyn and others, 2003).