Little Grand Mining District, Grand County, Utah, USAi

Regional Level Types
Little Grand Mining District	Mining District
Grand County	County
Utah	State
USA	Country

The heart of the Little Grand mining district is located about 15 mi southeast of Green River on the border of Emery and Grand Counties. The initial interest in the district was driven by manganese demands of the two World Wars with most of the production from 1915 to 1918. Despite the district’s modest production, it is still ranked as the second largest manganese producer in Utah. Total district metal production at modern metal prices is estimated at $5.4 million. The largest producers in the district are the C.F.&I. and nearby mines (Baker and others, 1952).
The Little Grand district is geologically situated in the Paradox Basin section of the Colorado Plateau. Geology in the Little Grand district consists of a very gently (2° to 4°) northeast-dipping section of Jurassic- and Cretaceous-age strata. The manganese deposits are synsedimentary (USGS Model 34b), primarily hosted in the Upper Jurassic Summerville and Morrison Formations, and the best deposits are in the upper part of the Summerville Formation. The orebodies consist of manganese oxide in thin blankets and nodules in limestone and as cementing material in sandstone. The ore minerals are dominantly pyrolusite, with subordinate psilomelane and manganite having Mn grades from 4% to 40%. Minor amounts of manganocalcite and rhodochrosite are also reported and accessory minerals include iron oxides, barite, and local veinlets of celestite gypsum (Baker and others, 1952).
The Little Grand Mn district also encompasses the Ten Mile Canyon U district. There is no reported U production from this area, and as a result, there is virtually no literature on the mineralization. Weak U-V mineralization is reportedly hosted in the Jurassic Salt Wash Member of the Morrison Formation.