Tungsten

In 1779 Peter Woulfe examined the mineral known as Wolframite and concluded it must contain a new substance. Scheel, in 1781, found that a new acid could be made from Tungsten (a name first applied in 1758 to a mineral known as Scheelite). Scheele and Berman suggested the possibility of obtaining a new metal by reducing this acid. The de Eelhuyar brothers found acid in Worlframite in 1783, which was identical to that found in Tungsten (tungstic acid). In that same year they succeeded in obtaining the element by the reduction of this acid with charcoal.
Tungsten is a transition metal in the group 6 (VIB) and it is in period 6. The word Tungsten comes from the Swedish words "Tungs" and "ten" meaning heavy stone. Tungsten occurs in wolframite, sheelite, heubnertie, and ferberite. Important deposits of tungsten occur in California, Colorado, South Korea, Bolivia, Russia, and Portugal. China is reported to have at least 75% of the world's tungsten resources. Natural tungsten contains five stable isotopes. Twenty-one other unstable isotopes are recognized. The metal is obtained commercially by reducing tungsten oxide with hydrogen or carbon. Pure tungsten is a steel gray to a white tin colored metal. Very pure tungsten can be cut with a hacksaw, and can be forged, spun, drawn, and extruded. The impure metal is brittle and can only be worked with great difficulty. Tungsten has the highest melting point of all metals with a melting point of 3410C, a boiling point of 5660C, and a tensile strength of 1650C. It has excellent corrosion resistance and is attacked only slightly by most mineral acids. The thermal expansion is about the same as borosilicate glass, which make the metal useful for glass to metal seals. Tungsten and its alloys are used extensively for filaments in electric lamps, electron and television tubes, and for metal evaporation work; for electrical contact points for automobile distributors; X-ray targets; windings and heating elements for electrical furnaces, and for many space craft and high temperature applications. High-speed tool steels, Hastelloy, stellite, and many other alloys containing Tungsten. Tungsten carbide is of great importance to the mining, metal working, and petroleum industries. Calcium and magnesium tungstates are widely used in fluorescent lighting; other states of tungsten are used in the chemical and tanning industries. Tungsten bronzes and other tungsten compounds are used in many paints. Tungsten powder costs $50.00 a pound.