Erickson Mining District, Utah, USAi

Regional Level Types
Erickson Mining District	Mining District
Utah	State
USA	Country

The Erickson (Indian Spring) mining district covers the southern and western Simpson Mountains of southern Tooele County about 32 mi west of Eureka. The district was organized in 1894 and became a modest Mn-Pb-Ag-Zn producer. Total district metal production at modern metal prices is estimated at $3.8 million. The Erickson district is the third largest Mn producer in Utah. The Bar X mine is probably the largest producer.
The Simpson Mountains are a small desert mountain range in the Basin and Range Province of western Utah. The range is composed of three structural blocks: (1) a northern block composed of Proterozoic and Lower Cambrian clastic meta- sedimentary rocks; (2) a central, easterly trending graben of Paleozoic sedimentary rocks; (3) and a southern block of folded Proterozoic clastic meta-sedimentary rocks. Mineralization is confined to the two southern blocks. The mineralization in the central graben is dominantly gently-dipping, epithermal Ag-Au veins (USGS Model 25c) with pyrite-tetrahedrite-chalcopyrite that constitute a small percentage of the district’s overall production (Thomas, 1958).
Mineralization in the southern block consists of Mn-Pb-Zn-Ag polymetallic veins (USGS Model 22c) in Neoproterozoic quartzites, metaconglomerates, and shales. These metasedimentary rocks are broadly folded into a large northerly trending and plunging anticline centered on Death Canyon. Locally these veins have strongly anomalous Mo and Sn. The southern block also has some small, Miocene-age high-silica rhyolitic intrusive bodies (~16 Ma).
The southern Erickson district mineralization occurs primarily as veins occupying northwesterly and easterly trending fault zones. The northwest-trending faults show greater brecciation and throw (Fry and Wilson, 1949). Mineralization is predominantly Pb-Zn-Ag in the middle reaches of Death Canyon near the Bar X mine, and Mn becomes more dominant in the mines/prospects to the north and east. The veins, generally south and west of the Bar X, have strongly anomalous Mo (1000 ppm), Sn (200 ppm), and weakly anomalous Cu in U.S. Geological Survey National Geochemical Database samples.