Occurrence

This metal occurs sparingly in nature as tungstate of calcium, of iron, and of manganese. The minerals are conspicuous on account of their high specific gravity.

Reduction. Metal

The concentrated mineral is fused with sodium carbonate which forms the soluble sodium tungstate and allows the removal of the other metals by filtration. From this solution acids precipitate the oxide of tungsten, W03. This oxide is reducible to the metal directly.

Ferro-Alloys

For the production of the ferro-alloys the oxide will be reduced along with some iron to act as carrier. This is the way it is put into steel. Ferrotungsten as reduced with iron in the electric furnace commonly runs over 70 per cent tungsten. There is a very great demand for the tungsten steels and their price often is well above a dollar a pound.

Modern Ductile Form

But tungsten can be reduced to metal more pure than this, when it appears as a gray powder without displaying any sign of malleability or ductility. A few years ago the research laboratory of a great industrial company learned how to make this metal in ductile form. The more it was heated and worked, the stronger and softer it became. Thus was discovered the strongest, most dense, and highest fusing metal we have. Its uses have developed in other fields, although it is used more than ever for filaments in incandescent-light bulbs. The strength of tungsten wires exceeds even the strength of the strongest steel wires. The one great restraint on many uses for such a metal is that, although its melting point is about 3000° C, yet this heating must be done with exclusion of air, lest the metal burn up with a flash.