WOLFRAMITE or WOLFRAM, a mineral consisting of an isomorphous mixture in varying proportions of the tungstates of iron and manganese, and MnW0,. Varieties with dom inant iron are often called ferberite, with dominant manganese, habnerite, but since iron and manganese have nearly the same atomic weight the percentage of tungsten reckoned as (about 76%) shows little variation and the difference is of no commer cial importance. Wolframite crystallizes in the monoclinic system, usually in prismatic forms, without end-faces, and there is a very perfect pinacoidal cleavage. The colour is dark brown or black, with a metallic lustre especially on cleavage faces. Hardness 5-5.5 and density 7.2-7.5.
Wolframite is very commonly associated with tin-ore in lodes and veins in and around granites. This form occurs in Corn
wall; north-west Spain and north Portugal; Saxony ; Tavoy (Lower Burma) ; the Malay Peninsula; Queensland; Tasmania. In the United States the biggest producer is Boulder Co., Colo rado, where there is no tin, but many gold veins, Wolframite is the chief ore of the metal tungsten, which is used as a constituent of high-speed and other special steels, as well as certain non-ferrous alloys; for the filaments of electric lamps; and for various other technical uses, often as sodium tungstate. During the World War there was a tremendous demand for tung sten steel for munition making, and many new sources of wolf ramite were developed. (R. H. RA.)