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
Polonium dioxide reaction of polonium dioxide with potassium hydroxide or potassium nitrate in air gives the colourless potassium polonite (KPoO): Polonium dioxide is closely related to the polonite anion (), similar to the relationship between polonium trioxide and the polonate anion (). Polonium dioxide has no uses outside of basic research. All polonium compounds, such as polonium dioxide, are extremely radioactive and thus must be handled in a glove box. The glove box must further be enclosed in another box similar to the glove box, maintained at a slightly lower pressure than the glove box to prevent the radioactive materials from leaking