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
Isotopes of uranium Isotopes of uranium Uranium (U) is a naturally occurring radioactive element that has no stable isotopes but two primordial isotopes (uranium-238 and uranium-235) that have long half-lives and are found in appreciable quantity in the Earth's crust, along with the decay product uranium-234. The standard atomic weight of natural uranium is . Other isotopes such as uranium-232 have been produced in breeder reactors. Naturally occurring uranium is composed of three major isotopes, uranium-238 (99.2739–99.2752% natural abundance), uranium-235 (0.7198–0.7202%), and uranium-234 (0.0050–0.0059%). All three isotopes are radioactive, creating radioisotopes, with the most abundant and stable being uranium-238 with a half-life of