Metallic element, symbol W, atomic number 74,
relative atomic mass 183.86. A grey hard
metal, insoluble except in a mixture of
nitric and hydrofluoric acids, it has the
highest melting point (3,370 degrees C) of
any metal. Tungsten is used in alloy steels
for armour plate, projectiles, high-speed
cutting tools, lamp filaments, and thermionic
valves. Its salts are used in the paint and
tanning industries. It was recognized and
named by Scheele in 1781, and discovered by
the d'Elhujar brothers in 1783. It occurs as
wolframite (FeWO4), scheelite (CaWO4), and
huberite (MnWO4).