wolframit

Wolframit, or wolframite, is an iron–manganese tungstate mineral and the most important ore of tungsten. It forms a solid solution between ferrous tungstate (FeWO4) and manganous tungstate (MnWO4), with a general formula (Fe,Mn)WO4. It is commonly associated with quartz, cassiterite, and other tungsten- and tin-bearing minerals in hydrothermal veins and granitic pegmatites, and it can occur in alluvial placer deposits derived from weathering of tungsten-bearing rocks.

Wolframit crystallizes in the monoclinic system. It occurs as prismatic, tabular, or brownish-black to black crystals, but more frequently as massive, dense aggregates. It has a metallic to submetallic luster, a high specific gravity around 7.0–7.5, and a Mohs hardness of about 4–4.5. The color is gray to brownish-black; the streak is pale gray. Crystals are sometimes elongated parallel to the c-axis.

Economically, wolframit is the principal ore of tungsten, alongside scheelite. Tungsten produced from wolframit is used to make hard metals, tungsten carbide, electrical filaments, and alloys for high-temperature and high-strength applications. Global production centers include China, Russia, Portugal, Bolivia, and Spain, among others.

The name wolframit derives from wolfram, the German name for tungsten; the mineral gives the chemical symbol W to tungsten.