Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and has a high melting point.

Where is a thorium found?

The main world resources of thorium are associated with monazite placer deposits in India, Brazil, Australia, the USA, Egypt, and Venezuela. The second most important thorium resources could be mined as by-product of REO from carbonatites (China, Greenland, Norway, Finland, and Sweden).

Is thorium found on Earth?

The abundance of thorium in Earth's crust is 6 parts per million by weight, according to Chemicool. According to Periodic Table, thorium is the 41st most abundant element in Earth's crust. Thorium is mainly mined in Australia, Canada, the United States, Russia and India, according to Minerals Education Coalition.