High Quality Content by WIKIPEDIA articles! Naturally occurring cadmium (Cd) is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays were never observed, due to extremely long half-life times. The two natural radioactive isotopes are 113Cd (beta decay, half-life is 7.7 ? 1015 years) and 116Cd (two-neutrino double beta decay, half-life is 2.9 ? 1019 years). The other three are 106Cd, 108Cd (double electron capture), and 114Cd (double beta decay); only lower limits on their half-life times have been set. At least three isotopes - 110Cd, 111Cd, and 112Cd - are absolutely stable (except, theoretically, to spontaneous fission). Among the isotopes absent in the natural cadmium, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours and the majority of these have...