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 dials 186 keV gamma emission 3% of the time. Also, Ra is rarely present without other transuranic elements or decay products, which may emit beta or gamma radiation. Therefore, the radiation hazards from radium paint may not be entirely removed by the varnish, case or container. Care should be taken to prevent the inhalation or ingestion of flakes or dust which may contain radioactive materials. Radium dials have been shown to have dose rates near the face of in excess of 10uSv / hr, which would deliver a dose equivalent to one days background exposure in around 20 minutes. This dose