April 20, 1902, the Curies Isolate Radium

On April 20, 1902, Marie and Pierre Curie managed to isolate the radioactive substance radium chloride from the mineral pitchblende in their Paris laboratory. The Curies discovered radium in 1898, along with another element that Marie named Polonium after her native Poland.

For their important work on radioactivity, the Curies were awarded the 1903 Nobel Prize in Physics. In 1906, Pierre Curie died, but Marie continued his work, isolating pure radium in 1910, which earned her a second Nobel, now in Chemistry, in 1911. Marie Sklodowska Curie, the first woman to win a Nobel Prize, was also the first person to win it twice. Radium was later used to treat cancer, and was important in the development of nuclear physics.