| Since gas mantles made with thorium are radioactive, their use has been phased out. |
| In addition to primeval heat, Earth's core also gets heat from radioactive decay of uranium, thorium, and potassium. |
| The concentrations of iron and thorium, for instance, have proved useful in distinguishing rock types from one another and in monitoring geochemical processes. |
| All natural rocks contain small amounts of uranium and thorium, which are radioactive and remain so for billions of years. |
| Alloyed thorium enhances the emission of thermions by lowering the work function barriers. |
| Among the commonly known alpha emitters are various isotopes of polonium, radium, thorium, uranium and all of the transuranium elements. |
