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
Radium Hill named the uranium-bearing mineral davidite after geologist and Antarctic explorer, Sir Edgeworth David. The mine was initially called "Smith's Carnotite Mine" (a similar uranium-bearing mineral) and in September 1906 Mawson proposed the name "Radium Hill". Smith worked the mine for the next two years before allowing the lease to lapse. Adjoining leases stretched for along the lode, with one being half-owned by Mawson. The Radium Hill Company took over the lease in 1908 and more shafts were sunk. Ore concentrate was transferred to refineries in New South Wales and Victoria. Radium had reached a price of ₤13,000 per gram in