Jáchymov 227 zentners [11.35 tonnes] were produced), nickel, bismuth and uranium ore were also extracted. There were also other industries: an enormous tobacco factory employed 1,000 women. In addition, there was the manufacture of gloves and corks and of bobbin lace. On 31 March 1873 the town almost entirely burnt down. At the end of the 19th century, Marie Curie discovered, in tons of pitchblende ore containing uraninite from Joachimsthal, the element radium, for which she won the Nobel Prize in Chemistry. Until the First World War this was the foremost source of radium in the world. The first radon spa
Uranium–thorium dating Uranium–thorium dating Uranium–thorium dating, also called thorium-230 dating, uranium-series disequilibrium dating or uranium-series dating, is a radiometric dating technique established in the 1960s which has been used since the 1970s to determine the age of calcium carbonate materials such as speleothem or coral. Unlike other commonly used radiometric dating techniques such as rubidium–strontium or uranium–lead dating, the uranium-thorium technique does not measure accumulation of a stable end-member decay product. Instead, it calculates an age from the degree to which secular equilibrium has been restored between the radioactive isotope thorium-230 and its radioactive parent uranium-234 within a sample. Thorium is not