Return to periodic table H' at. Scheele and Bergman suggested the possibility of obtaining a new metal by reducing this acid. Important deposits of tungsten occur in California, North Carolina, South Korea, Bolivia, U.S.S.R., and Portugul.
Natural tungsten contains five stable isotopes.
Twelve other unstable isotopes are recog- nized. The metal is obtained commercially by reducing tungstic oxide with hydrogen or cargon. Pure tungsten is a steel gray to tin-white 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 be worked only with difficulty.