61Pm Promethium

Year Discovered


Discovered By

J. A. Marinsky, Lawrence Glendenin and Charles Coryell of the USA

Biological Rating

Not necessary for life.


Named after Prometheus of Greek myth. Promethium is the only radioactive lanthanide metal, and is one of two elements lighter than bismuth which have no non-radioactive isotopes (technetium is the other). It is not found in measurable quantities on Earth, but has been found in the atmospheres of stars. Promethium is used in special miniature atomic batteries and certain photoelectric cells, as well as in certain lights and signs, as promethium itself glows. It is used in fluorescent lighting starters, and has potential for providing heat and power for satellites and space probes. The most stable isotope of promethium has a half-life of 17.7 years.

Biological Benefits

Promethium has no known biological benefit.

Role in Life Processes

No known benefits for life processes in plants and animals.


Any natural promethium the Earth possessed has long since disappeared. It is believed to be present in trace quantities in uranium minerals, as it is part of uranium’s radioactive decay series. It generally is obtained from fission products in nuclear reactors.