Carbonate Mining District, Uinta Mountains, Uintah County, Utah, USAi

Regional Level Types
Carbonate Mining District	Mining District
Uinta Mountains	Mountain Range
Uintah County	County
Utah	State
USA	Country

The Carbonate mining district is in northern Uintah County, about 25 mi north of Vernal. The mineral deposits in the district were initially discovered in the late 1880s. The district was a significant Cu-Ag producer in the 1890s and early 1900s. In the 1940s and 1950s, some Pb-Zn-Ag ore was produced from the district. Total district metal production at modern metal prices is estimated at $9 million. Most of the workings occur above an elevation of 9000 ft.
The Carbonate district is geologically situated on the southeastern flank of the Uinta Mountains of the Middle Rocky Mountain province. The district consists of a few small mines and several prospects in a thin, gently (5° to 20°) south-southeast-dipping section of Cambrian and Mississippian carbonate rocks sitting on top of Neoproterozoic Uinta Mountain Group sandstones. Major faulting and igneous rocks are not recognized in the district.
Most of the ores are replacement deposits in silty-sandy limestone of the Lower Mississippian Madison (?) Limestone. The largest producer was the Dyer Cu mine which accounted for several hundred tons of 50% Cu with some byproduct Ag. The orebodies are small, irregular “pockets” of primary chalcocite and possibly bornite with little pyrite. In addition to Cu-Ag, the ore is anomalous in F, Zn, Pb, As, Sb, Hg, and Mo, in decreasing order of importance (Conn, 2005).
The Pope Fe mine is located a few hundred feet downslope from the Dyer at the contact between the Cambrian Lodore Formation limestone and the underlying Uinta Mountain Group sandstone and shale. The Pope ores are red hematite to specularite with minor magnetite.
The Silver King mine, a mile to the south of the Dyer, produced a few tons of hand cobbed, Pb-Zn-Cu-Ag-Au ore from a replacement deposit in a higher section of the Madison Limestone. The primary ore minerals are galena and sphalerite with little pyrite. Silver King ore samples are also anomalous in As, Sb, and Hg (Conn, 2005).