TUNGSTEN The metal tungsten has played a very important part within the last quarter of a century in the progress of the electrical and mechanical arts. Recent developments indicate that its importance will be still greater in the coming years. It is a chief com ponent of tool steels and enters into the manufacture of heat resisting and non-corrosive steels. Recently tools have been in vented consisting of pure tungsten carbide imbedded in a metallic matrix which have quite revolutionized the art of cutting and shaping not only metals but also such unworkable materials as porcelain, glass, bakelite, etc. Tungsten is also used in the light filaments, contact points and X-ray targets of the electrical indus try besides entering as a component into magnet steels. With the rapid strides made in radio and television its use in the electric industry may grow to much greater proportions.
The important commercial minerals of tungsten fall under two main groups, the tungstates of the metals iron (ferberite) and manganese (huebnerite), and a mixture of both (wolframite) ; and the tungstate of calcium (scheelite). Until recently scheelite was the more coveted mineral for metallurgical purposes owing to its greater purity, but progress in smelting and reduction practice has offset this advantage. Nature has provided a very wide-spread mineralogical occurrence of tungsten, both in the primary and secondary formations of the earth. The primary deposits are in variably associated with granitoid rocks and are most important, while secondary deposits form the lesser resources. Tungsten has
been a comparatively cheap metal and it has been the endeavour of producers to get their ore supplies as cheaply as possible. The supremacy of tungsten production has floated from country to country as the surface ore was exhausted and more expensive deeper mining made necessary. Owing to its great importance in munitions work it is the endeavour of the principal Govern ments of the world to keep their indigenous tungsten resources under development in spite of the lower cost of foreign minerals.
Since 1913 tungsten production has increased by more than four-fold, reaching 34,800 metric tons of concentrates, contain ing 16,600 tons of metal, in 1937. The outputs of the leading pro ducers and their percentage of the total output in various years is as follows: In 1913—Burma 19%, United States 17%, Portugal 14%, Australia 10% in 19i 8—China 33%, United States 14%, Burma 13%, Bolivia 12%; in 1929—China 63%, Bolivia io%, Burma 9%, United States 4% ; in 1937—China 47%, Burma 16%, United States 9%, Bolivia 5%.
No data are available on reserves except in the United States, where the known reserves are estimated to be about equal in amount to the output of the past 20 years, but equal to consump tion for only 8 years prior to 1938. Full utilization of these re serves will be dependent on maintaining sufficiently high prices to cover the abnormally high production costs inherent in these low grade mines, which require a heavy tariff protection to keep them going. (G. A. Ro.)