This element is obtained either as a heavy dark-gray metal, which is very hard and difficult to fuse, or as a dark-gray powder. It is used as an alloy with iron, one part of tungsten to nine of steel, to make the ferrotungsten, which has extraordinary hardness, and is used mostly for high-speed tools. Tungsten is also one of the three metals (cobalt, chromium and tungsten) which are alloyed together to make stellite. Some of the tungsten supply is also used to make the films in incandescent lamps, and in some of the chemical industries. It has but one important ore, wolframite, and this is found in the United States in but small quantities; so that we ordinarily have to import the greater part of what we use. During the last war, under the stimulus of high prices and the urge of necessity, we did find and produce substantial quantities of tungsten. China is the world’s largest producer of tungsten ore with Burma second, and the United States a poor third.
[Wolframite]
(FeMn)WO₄
Occurs in monoclinic crystals or in crystalline masses; hardness 5.5; specific gravity 7.4; color dark-brown to black; streak nearly black; luster submetallic; opaque on thin edges.
If in crystals the form will serve to distinguish this mineral from cassiterite and ilmenite, the two which it most resembles; but if it is massive the only sure way to decide is to put a piece in strong sulphuric acid; if it dissolves and throws down a yellow precipitate (tungstic acid) it is wolframite.
Like the two other minerals mentioned above it occurs in veins in igneous rocks, being associated with high temperatures. As it is almost insoluble in water, like cassiterite and ilmenite, it is likely to occur with them in the sands which are the result of the disintegration of the rocks which carried the minerals; and so a large part of the supply today comes from placer deposits.
It is found in Connecticut, North Carolina, Missouri, Colorado, and California.
Radium, Uranium and Vanadium
These three metals are all rare and occur together. Radium, discovered in 1898, is a heavy metal which has proved very useful because of its radio-activity, that is, its power of giving off or radiating tiny particles of matter known as X-rays, part of which are charged with positive electricity, and part of them with negative electricity. The ability of these rays to pass through other substances has made possible photographing the denser substances within those less dense, as the bones within the flesh, or metal within leather or wood, etc. The rays have proved of great value medicinally, and are also used to make objects luminous in the dark. These X-rays are also used in the study of the ultimate structure of matter, as it can be thus obtained in such small units.
Uranium is another element which is radio-active and can be used for many of the same purposes as radium.
Vanadium, the third of these associated metals, and the commonest of the group, is not radio-active. It is a silvery-white metal, mostly used as an alloy with steel to give it great hardness.