Wolframite

Wolframite is a mineral group that consists of iron and manganese tungstate, with the chemical formula (Fe,Mn)WO4. It forms a solid-solution series between ferrowolframite (Fe-rich) and manganowolframite (Mn-rich). Wolframite is the principal ore of tungsten, although scheelite (CaWO4) also contributes in many deposits.

Its appearance is typically dark brown to black, with a metallic to submetallic luster. It forms elongate prismatic crystals or accumulates in massive, granular aggregates. Hardness is about 4–4.5 on the Mohs scale, and specific gravity ranges from about 7.0 to 7.6. It crystallizes in the monoclinic system and commonly shows only imperfect cleavage.

Wolframite occurs in hydrothermal veins and greisen associated with granitic intrusions, as well as tin-tungsten deposits such as pegmatites and greisen bodies. It is commonly found with quartz, cassiterite, scheelite, and tourmaline.

Economically, wolframite is an important source of tungsten. Ores are processed to extract tungsten, which is used for hard alloys, tungsten carbide, electrical components, and other industrial applications. Major producers include China, Portugal, Bolivia, Russia, Spain, and Canada.