(also Th)mass noun
The chemical element of atomic number 90, a white radioactive metal of the actinide series.‘In addition to primeval heat, Earth's core also gets heat from radioactive decay of uranium, thorium, and potassium.’
- ‘All natural rocks contain small amounts of uranium and thorium, which are radioactive and remain so for billions of years.’
- ‘The analysis shows that manganese, titanium, hafnium, thorium, phosphorus, and the rare-earth elements play a significant role in discriminating between zircons of various origins.’
- ‘Deep within Earth, some diamonds come into contact with radioactive materials, such as thorium or uranium, that can impart a unique signature known as a radiation halo.’
- ‘The concentrations of iron and thorium, for instance, have proved useful in distinguishing rock types from one another and in monitoring geochemical processes.’
Mid 19th century named after the god Thor.
Are You Learning English? Here Are Our Top English Tips