Radium seventh of a gram of radium. One kilogram of the Earth's crust contains about 900 picograms of radium, and one liter of sea water contains about 89 femtograms of radium. Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. They separated out an element similar to bismuth from pitchblende in July 1898, that turned out to be polonium. They then separated out a radioactive mixture consisting mostly of two
Radium Girls a two-year statute of limitations, but settled out of court in 1928. Five women in Illinois who were employees of the Radium Dial Company (which was unaffiliated with the United States Radium Corporation) sued their employer under Illinois law, winning damages in 1938. From 1917 to 1926, U.S. Radium Corporation, originally called the Radium Luminous Material Corporation, was engaged in the extraction and purification of radium from carnotite ore to produce luminous paints, which were marketed under the brand name "Undark". The ore was mined from the Paradox Valley in Colorado and other "Undark mines" in Utah. As a defense