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.
[Carnotite]
K₂O·2U₂O₃·V₂O₅·3H₂O
[Pl. 27]
Occurs in earthy masses; color yellow.
This mineral is included here, not because it is common, but because it is of such great interest. It is the chief source of supply in the United States of radium, uranium and vanadium. It is a lemon-yellow earth or powder, which looks a little like orpiment. It is however found in a sandstone, instead of where hot waters have deposed minerals. From a ton of this ore about 10 pounds of uranium oxide, 55 pounds of vanadium and ¹/₁₀₀₀th of a gram of radium are obtained. Carnotite is found in south-west Colorado and south-east Utah, and on Carrizo Mountain on the line between Arizona and New Mexico.