Box Elder Mining District, Box Elder County, Utah, USAi

Regional Level Types
Box Elder Mining District	Mining District
Box Elder County	County
Utah	State
USA	Country

The Box Elder mining district is located about 5 mi north of Brigham City in extreme eastern Box Elder County. Mineralization was initially discovered in 1889 with the main period of production from 1908 to 1917. District production has been small and is estimated at roughly 1000 tons of Sb ore likely making this the second largest Sb producer in Utah. Total district metal production at modern metal prices is estimated at $360,000. Box Elder also has some minor production of Cu-rich polymetallic ore (Doelling, 1980). The Dry Lake Sb mine is the largest producer in the district.
The Box Elder district is situated on the steep western face of the Wellsville Mountains of the Middle Rocky Mountain province. The Dry Lake Sb mine (incorrectly labeled the Copper Blossom mine on the U.S. Geological Survey Brigham City 7.5′ topographic map) lies on the south end of the district and accounts for over 70% of the Box Elder district’s estimated production value. The mineralization occurs along a steeply north-dipping, N. 85° E.-trending quartz vein in a fault zone cutting northeast-dipping Middle Cambrian Blacksmith Formation carbonates just beneath the overlying Hodges Shale Member of the Bloomington Formation. The host carbonate is white and gray, fine-grained limestone overlain by thin-bedded limy shales (Jensen and King, 1999). The main ore zone is a few feet wide and extends about 50 ft along strike. The primary ore averages about 10% Sb as stibnite, which is typically fresh in the quartz vein, but has been oxidized (stibiconite?) in the vein walls and adjoining carbonate wallrocks (USGS Model 27d). The deposit also contains trace Cu, Pb, As, Ag, and Au (Doelling, 1980).
The main base metal occurrences, the Baker mine (Cu-Pb-Ag) and Copper Blossom mine (Cu-Pb-Zn-Ag), are both on the same northeast-trending, southeast-dipping fault zone about a mile north of the Dry Lake Sb mine. The Baker mine is farther east and up section in the Ordovician Garden City Formation and the Copper Blossom is lower on the mountain in the Cambrian Nounan Formation. These deposits are principally associated with Fe-oxide-stained brecciated zones and calcite veins. Toward the north end of the district the Cataract Canyon (Pb-Zn) prospects are also located along northeast-trending fault zones in the Cambrian to Silurian carbonates (Doelling, 1980; Jensen and King, 1999). No intrusive igneous rocks are recognized in the district.