Wolframitetype

Wolframite-type refers to a group of tungsten oxide minerals that share the same monoclinic crystal structure as wolframite. The principal endmembers are ferberite, FeWO4, and hübnerite, MnWO4, with a continuous solid solution between them described by the formula (Mn,Fe)WO4. The term is used in mineralogy to describe minerals that adopt the wolframite structure, even when varied by substituting Mn2+ and Fe2+.

Crystal structure and composition are typical of wolframite-type minerals: they are monoclinic and consist of alternating octahedra of tungsten(VI) coordinated by oxygen and divalent metal octahedra (MnO6 or FeO6) linked into a dense framework. The structure forms characteristic chains of octahedra running along one crystallographic axis, producing a compact, highly anisotropic mineral. The Mn–Fe substitution yields a continuous solid solution, with properties varying across the series.

Occurrence and associations: wolframite-type minerals occur in hydrothermal tungsten veins and in granitic and metamorphic environments, often in tin-tungsten districts. They are commonly found with cassiterite (SnO2), scheelite (CaWO4), quartz, and other tungsten- or tin-bearing minerals. These minerals are typically formed at moderate to high temperatures in ore-forming systems.

Economic significance: as tungsten ore minerals, wolframite-type minerals are important sources of tungsten, especially in deposits where wolframite is the dominant tungstate mineral. They are mined and processed to yield tungsten concentrates, which are refined for industrial uses such as hard metals and alloys.

Etymology and usage: the name wolframite derives from wolfram, the German name for tungsten. The term wolframite-type is used to describe minerals that share the same crystal structure as wolframite, including ferberite and hübnerite.