Secrets of radioactive 'promethium' — a rare earth element with mysterious applications — uncovered after 80-year search

An artist's rendering of a microscopic view of the promethium element.

For the first time, scientists have revealed crucial properties of the mysterious, radioactive substance promethium — nearly eight decades after the elusive rare earth element was discovered.

Promethium is one of the 15 lanthanide elements at the bottom of the periodic table. Also known as the rare earths, these metals exhibit a number of useful properties, including strong magnetism and unusual optical characteristics, making them particularly important in modern electronic devices.