l`frəmīt'), reddish-brown to grayish-black lustrous mineral, a tungstate of iron and manganese, (Fe,Mn)Wo4, occurring in crystals of the monoclinic system. It is the chief ore of the metal tungsten. Widely distributed in nature, it is mined in England, Portugal, Bolivia, Myanmar and the Malay Peninsula, S China, Australia, and W United States.wolframite [′wu̇l·frə‚mīt]
Wolframite
a mineral, formula (Fe, Mn) [WO4]; belongs to the isomorphous series whose terminal members are huebnerite, Mn[WO4], and ferberite, Fe[WO4]. It contains 74-76 percent WO3. Characteristic admixtures are MgO, Ta2O5, Nb2O5, ThO2, and Sc2O3. The content of niobium and tantalum is associated with an isomorphous impurity, but more often with very fine inclusions of minerals of the columbite group. It crystallizes in a monoclinic system. Laminar, thick-tabular, prismatic crystals, minute laminar grains, and coarse-grained aggregates are common. Wolframite is brownish black, huebnerite is reddish, and ferberite is black. The luster is bright to diamondlike. Hardness on the mineralogical scale, 5-5.5; density, 6,700 kg/m3 for huebnerite, and 7,500 kg/m3 for ferberite. Wolframite is found in greisens and quartz veins associated with muscovite, topaz, fluorite, beryl, bismuthine, cassiterite, molybdenite, arsenopyrite and, rarely, antimonite. It is sometimes replaced by scheelite. In an oxidation zone, wolframite is partly replaced by tungsten ochers (tungstite) and ferritungstite.
Wolframite is the main ore mineral from which tungsten is obtained. When it contains large amounts of Sc and Ta, they can be extracted as by-products.
REFERENCE
Barabanov, V. F. Mineralogiia vol’framitovykh mestorozhdenii Vostochnogo Zabaikal’ia [vol. 1]. Leningrad, 1961.How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content.
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