Radium occurs naturally as uranium decays - though only in very small quantities. It took many tonnes of pitchblende to produce the tenth of a gram of radium that the Curies eventually extracted. It's ...

A picocurie is about a trillionth of a gram of radium. According to the Centers for Disease Control, most people are exposed to small amounts of the radioactive element in everyday life ...

AFTER reading Arrhenius's vivid account 1 of the bombardment of the earth ... judging from the analysis, 0.637 × 10 12 gram of radium per gram, or a little less than was found in crystals of ...