All isotopes of francium decay into astatine, radium, or radon. Curie worked with his wife in isolating polonium and radium. The isotopes of francium decay quickly into astatine, radium, and radon. Francium is a highly radioactive metal that decays into astatine, radium, and radon. EPA has issued standards for alpha particles, beta particles and photon emitters, radium and uranium. The decay products of Th include more dangerous radionuclides such as radium and radon. The Eldorado Mine at Port Radium was a source of uranium ore. Radon is formed in the lithosphere by the alpha decay of radium. Tritium has replaced radioluminescent paint containing radium in this application. Some of the few practical uses of radium are derived from its radioactive properties. One ton of pitchblende typically yields about one seventh of a gram of radium. This property made zinc sulfide useful in the dials of radium watches. This radiation is a small portion of the total emitted during radium 226 decay. In water, it is more soluble than radium chloride. It often contains radium and its decay products.