Radium

Radium is a silvery-white radioactive metal that glows faintly blue in the dark. Marie and Pierre Curie discovered it in 1898 in uranium ore, naming it from the Latin radius, ray. Marie Curie and André-Louis Debierne isolated the pure metal in 1910. Its common form, radium-226, has a half-life of about 1,600 years.

In the early 1900s radium was a sensation, painted on glow-in-the-dark watch dials and even added to tonics and cosmetics. The young women who painted dials, known as the Radium Girls, suffered terrible illnesses, which helped bring in worker safety laws. Today radium-223 is used as a medicine for prostate cancer that has spread to the bones, where it delivers radiation directly to the tumors.