ionium
/aɪˈoʊniəm/
noun
- A radioactive isotope of thorium (thorium-230) that is an intermediate in the decay of uranium to radium.
- The decay of ionium produces radium, which was once used in glow-in-the-dark paint.
- Scientists study ionium to learn about the age of ocean sediments.
- Ionium is found in small amounts in uranium ores.