Blawn Mountain Mining District, Beaver County, Utah, USAi

Regional Level Types
Blawn Mountain Mining District	Mining District
Beaver County	County
Utah	State
USA	Country

The Blawn Mountain mining district is in southwestern Beaver County approximately 30 miles southwest of Milford. Mineralization was first discovered in the district in the 1880s and the district became a modest U-F and kaolinite producer. Total district metal production at modern metal prices is estimated at $1.2 million. The Staats underground U-F mine is the only significant metal mine along with a nearby kaolinite clay open pit.

The Blawn Mountain district is in the southern Wah Wah Mountains in the Basin and Range Province. The mineralization at the Staats mine is associated with one of several small, high-silica, Miocene rhyolite porphyry plugs known to be associated with the Miocene Blawn Formation volcanic rocks. These plugs include the Pine Grove porphyry, Staats rhyolite, and the smaller Blawn Wash plugs. The Staats topaz rhyolite plug (20.2 Ma) intrudes a sequence of Silurian and Devonian carbonates and is adjacent to the U-F mineralization at the Staats mine (Mehnert and others, 1978).

The Staats fluorite mine was worked by a small open cut and has an estimated 800 ft of underground workings (USGS Model 26b). Some 4855 tons of fluorite were mined from 1935 to 1951. During the 1950s, uranium was discovered at the Staats mine and an additional 1994 tons of 0.26% U3O8 hand-sorted ore were shipped. The area was heavily explored for U again in the early 1970s and then for Mo in the late 1970s and early 1980s, following the discovery of the deep, Climax-type porphyry Mo deposit at Pine Grove 7 miles to the northwest.

The Staats fluorite ore zones, grading approximately 75% to 90% CaF2, are typically a few feet in width, a few tens to just over 100 feet in length, and occur near the rhyolite contact. The autunite and uranophane after uraninite occur as small flakes and coatings in gouge zones adjacent to the fluorite with typical grades of less than 0.2% U3O8. Lindsey and Osmonson (1978) report the occurrence of very low-level geochemical anomalies for Be, Mo, and Sn associated with the rhyolite stock. D.A. Lindsey (retired USGS, written communication, July 2007) notes the occurrence of good crystalline cassiterite in a fluorspar breccia near the Staats mine.

Between 2003 and 2010 about 500,000 tons of high alumina (about 30% Al2O3) kaolinite clay was recovered from a ridge top open-pit mine on Blawn Mountain. The clay was hauled to the Leamington cement plant as a premium alumina feed to boost kiln throughput. The clay was valued at about $30/ton. The kaolinite was found along a fault contact between altered Ordovician dolomite and Tertiary intrusive rhyolite. Mining operations ceased due to cement plant concerns about the high Hg content of the clay.