Naturally occurring
cobalt (
Co) is composed of 1 stable
isotope,
59Co. 28
radioisotopes have been characterized with the most stable being
60Co with a
half-life of 5.2714 years,
57Co with a half-life of 271.8 days,
56Co with a half-life of 77.27 days, and
58Co with a half-life of 70.86 days. All of the remaining
radioactive isotopes have half-lives that are less than 18 hours and the majority of these have half-lives that are less than 1 second. This element also has 11
meta states, all of which have half-lives less than 15 minutes.