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Show " Tungsten of Great Value .Tungsten ' or, wolf rain - IsL.-JAfiftUi civ e'.WV'A't. "isnlated -bythe' brothers d'El-Imjart d'El-Imjart Ire 1783,, after jSchele. bad, In nVl, Isolated tungstlc acid. Tungsten Is not found native, but occurs as the tungstate of Iron and manganese in the mineral wolframite, as the calcium tungstate or scbeelite, as the trioxlde or wolfram ochre, and in small quantities quan-tities in other minerals. Tungsten minerals-are almost invariably found In tin ores. It is used to increase the hardness and tenacity of steel and thus improve it as a material for hard tools. Coolidge has succeeded in rendering ren-dering tungsten malfeable and ductile, and at present tungsten wire is widely used for making Incandescent lamp ! filaments. |