Cobalt abundance but natural compounds of cobalt are numerous and all amounts of cobalt compounds are found in most rocks, soil, plants, and animals. In nature, cobalt is frequently associated with nickel. Both are characteristic components of meteoric iron, though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric iron alloys may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal, though neither element is seen in that form in the ancient terrestrial crust. Cobalt in compound form occurs in copper and nickel minerals. It is
Cobalt stable cobalt isotope and the only isotope that exists naturally on Earth. Twenty-two radioisotopes have been characterized; the most stable, Co has a half-life of 5.2714 years, and Co has a half-life of 271.8 days, Co a half-life of 77.27 days, and Co a half-life of 70.86 days. All the other radioactive isotopes of cobalt have half-lives shorter than 18 hours, and in most cases shorter than 1 second. This element also has 4 meta states, all of which have half-lives shorter than 15 minutes. The isotopes of cobalt range in atomic weight from 50 u (Co) to 73 u