Thorium when freshly cut
Thorium is a naturally occurring radioactive element. It is soft metal with a bright silvery luster when freshly cut. It has a melting point of about 1700°C (3100°F) and a boiling point of about 4500°C (8100°F). It is relatively soft, with hardness about equal to that of lead. It is even more abundant than uranium, ranking number 39 in abundance among the elements in earth's crust. Thorium occurs in minerals Thorite, SiO2. ThO2.nH2O, Thorianite contains mainly ThO2, UO2 and Monazite sand contains about 9% of ThO2.
No more than a few hundred tons of thorium is produced annually. About one–half of this production goes to the manufacture of gas mantles, insulated chambers in which fuel is burned. The rest goes for use as nuclear fuel, in sun lamps (electric lamps that emit radiation; often used for tanning), in photoelectric cells (vacuum tubes in which electric current flows when light strikes the photosensitive or light sensitive cathode) and in the production of other alloys (a mixture of two or more metals or a metal and a non–metal).