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

Regional Level Types
Newfoundland Mining District	Mining District
Newfoundland Mountains	Mountain Range
Box Elder County	County
Utah	State
USA	Country

The Newfoundland mining district occupies the north end of the desolate Newfoundland Mountains about 48 mi northeast of Wendover in south-central Box Elder County. The Newfoundland range is one of the most isolated in Utah, only accessible by a gravel road from the Southern Pacific Railroad service road at Groome station (31 mi east of Lucin). The district was organized in 1872 and had minor, early production from Ag-Cu-Pb veins followed by renewed activity in the 1950s when small shipments of W and Cu were produced (Doelling, 1980). The Newfoundland district is small and had only limited production of W (~85% of production value) and subordinate Ag-Cu ±Pb ores. Total district metal production at modern metal prices is estimated at $81,000. The Desert Flower W mine is probably the largest producer.
The Newfoundland Mountains are a 19-mi-long, northerly trending range in the West Desert of the eastern Basin and Range Province. The range consists of generally west-dipping Paleozoic rocks that were intruded by one large (~10 sq mi), Late Jurassic (~150 Ma), quartz-monzonite stock, three associated smaller plugs, and numerous dikes farther south (Allmendinger and Jordan, 1984). Regional aeromagnetic surveys suggest that these small plugs connect to the main stock at depth, and the main stock also underlies the pediment west of Miners Basin. The stocks are generally light-colored, porphyritic, biotite-hornblende quartz monzonite. The largest stock ranges in texture and composition from dark, coarse-grained, porphyritic granodiorite along the margins to a light-colored, fine-grained, more equigranular, quartz monzonite core. The core of the larger stock and the entire smaller, south-central stock are both weakly, but pervasively, altered to clay-chlorite (Allmendinger and Jordan, 1984). The dikes are generally biotite-feldspar latite porphyries, trend either northeast or northwest, and are locally altered and associated with mineralization.
Mineralization in the Newfoundland district can be divided into two broad types: W skarns and base metal-bearing quartz veins. Tungsten mineralization occurs within the contact metamorphic aureole of the plugs, mostly marble and hornfels, and is generally hosted in the Ordovician Garden City Limestone. Small scheelite lenses occur in garnet skarn (USGS Model 14a) immediately adjoining the south-central stock. Tungsten, in the form of wolframite, is also reported from the Copper Flat area to the northeast of the large stock (Doelling, 1980). Tungsten grades at the Desert Flower mine ran about 1.25% WO3.
The Ag-Cu-Pb ores occur in narrow, northwest-trending quartz veins typically about a mile from the stocks. In addition to chalcopyrite and galena, bismuthinite is reported from the Stone House Cu-Ag veins in Miners Basin on the west-side of the range. A few scattered base metal prospects also occur a few miles south of the main district.