Show tungsten of great value tungsten or wolfram la Is a metallic element isolated by the brothers del hajart in 1783 after had lo in 1771 isolated add acid tungsten Is not found native but occurs occur as the of iron and manganese la in the mineral as the calcium tung stats or scheelite its as the or wolfram ochre achre and in small quan titles in other minerals tungsten minerals are almost invariably found la in tin ores it Is used to increase the hardness and tenacity of steel and thus improve it as a material for or hard bard tools coolidge has succeeded la in ren desing tungsten malleable and ductile abd at present tungsten wire WIM to Is widely used for making incandescent lop jap filaments |