Mineral Forms of Tungsten at the Porokhovskoe and Yugo-Konevskoe Deposits (Southern Urals)

Ore hand specimens and technological ore samples from the greisen-type Porokhovskoe and Yugo-Konevskoe tungsten deposits in the Southern Urals were studied. The major tungsten minerals in primary ores of both deposits are hübnerite and scheelite. Secondary and accessory minerals are pyrite, chalcopyrite and molybdenite; rare minerals are sphalerite, galena, bismuthinite, aikinite, unidentified Bi chalcogenides and sulfosalts, magnetite, rutile, ilmenite, titanite, and columbite. Veins are mainly composed by quartz–muscovite aggregate with secondary (calcite, dolomite, and fluorite), minor (chlorite and amphibole), and accessory (zircon, apatite, and uraninite). No distinct zonation in the distribution pattern of wolframite with varying Fe content relative to the Yugo-Konevsky granite pluton is identified. However, wolframites from the Northern area of the Porokhovskoe deposit are enriched in Fe compared to those from the Central area and Yugo-Konevskoe deposit. Along with through vein wolframite and scheelite, the oxidized ores also contain Fe and Mn oxyhydroxides, malachite, pyromorphite, and bromargyrite. Tungsten enters the composition of Mn and Fe oxyhydroxides, which replace wolframite and less often sulfides. The WO3 content in pseudomorphs of Mn and Fe oxyhydroxides after hübnerite reaches 18 wt %. Single grains of stolzite and russellite are found. According to the results of phase chemical analysis of technological samples, the amount of tungstite in oxidized ores is minor. Due to this, all ores of both deposits can be ascribed to primary technological type.