In 1779 Peter Woulfe examined the mineral now known as wolframite and concluded it must contain a new substance. Scheele and Berman suggested the possibility of obtaining a new metal by reducing this acid. Important deposits of tungsten occur in California, Colorado, South Korea, Bolivia, Russia, and Portugal.
Natural tungsten contains five stable isotopes.
Thirty two other unstable isotopes and isomers are recognized. The metal is obtained commercially by reducing tungsten oxide with hydrogen or carbon. Very pure tungsten can be cut with a hacksaw, and can be forged, spun, drawn, and extruded. The impure metal is brittle and can be worked only with difficulty. Tungsten has the highest melting point of all metals, and at temperatures over 1650 deg C has the highest tensile strength.