Radium of radium Curie used the residues after extraction of uranium from pitchblende. The uranium had been extracted by dissolution in sulfuric acid leaving radium sulfate, which is similar to barium sulfate but even less soluble in the residues. The residues also contained rather substantial amounts of barium sulfate which thus acted as a carrier for the radium sulfate. The first steps of the radium extraction process involved boiling with sodium hydroxide followed by hydrochloric acid treatment to remove as much as possible of other compounds. The remaining residue was then treated with sodium carbonate to convert the barium sulfate into
Uranium-238 control. Around 99.284% of natural uranium's mass is uranium-238, which has a half-life of 1.41 seconds (4.468 years, or 4.468 billion years). Due to its natural abundance and half-life relative to other radioactive elements, U produces ~40% of the radioactive heat produced within the Earth. U decay contributes 6 electron anti-neutrinos per decay (1 per beta decay), resulting in a large detectable geoneutrino signal when decays occur within the Earth. The decay of U to daughter isotopes is extensively used in radiometric dating, particularly for material older than ~ 1 million years. Depleted uranium has an even higher concentration of