Show TUNGSTEN tungsten has been important commercially for a long time especially in high speed steel states C W davis assistant chemist department of the interior in bulletin just issued by the bureau of mines this use has stimulated the search for tungsten minerals throughout the world the following are the principal tungsten minerals scheelite a of calcium specific dra g dragity cavity vity 59 to 61 6 1 a dark grayish black mineral specific gravity 68 it consists principally of of iron but may contain small traces of manganese and tung states of iron and manganese the percentage of manganese practically determines ter mines the mineral although althou gl there are gradations that make classification difficult under either head typical carries about 20 per er cent man a oxide and typical 5 to 7 per cent scheelite is found mainly in the atolia district of california the largest deposits of in the unites states are in boulder county colo small deposits of and are scattered through new mexico arizona nevada and south dakota tungsten deposits occur also daso in burma china queensland portugal new south wales ar argentina arentina entina and bolivia in china has been found in placer deposits associated with small quantities of tin apart from the ores the products that have to be analyzed are metallic tungsten ano ana intermediate products and the various tungsten steels metallic tungsten is obtained by the reduction of the oxide and may contain different tungsten oxides due to incomplete reduction as well as other impurities carries from 50 to 80 per cent metallic tungsten high speed steel contains as much as 16 or 17 per cent metallic tungsten self hardening steels or those requiring no tempering after forging contain as little as 2 or 3 per cent with 6 or 7 per cent chromium extremely pure tungsten is used in filaments for incandescent lamps after repeated swaging and beatin heating has made the metal ducai ductile le and fibrous |