An artificial radioactive isotope of cobalt with an atomic mass of 59.9338 and a half-life of 5.3 years. It is produced from the stable cobalt-59 by neutron irradiation in a nuclear reactor. It decays by beta decay to nickel-60. The gamma radiation from cobalt-60 is used in place of X-rays or alpha rays from radium in the inspection of industrial materials to reveal internal structure, flaws, or foreign objects. It is also used in radiotherapy, as a radioactive tracer, and in research.