Cobalt "goblin", a superstitious term used for the ore of cobalt by miners. The first attempts to smelt those ores for copper or nickel failed, yielding simply powder (cobalt(II) oxide) instead. Because the primary ores of cobalt always contain arsenic, smelting the ore oxidized the arsenic into the highly toxic and volatile arsenic oxide, adding to the notoriety of the ore. Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt circa 1735, showing it to be a previously unknown element, different from bismuth and other traditional metals. Brandt called it a new "semi-metal". He showed that compounds of cobalt metal
Isotopes of cobalt an excited state of the Fe nucleus, which in turn decays to the ground state with emission of a gamma ray. Measurement of the gamma ray spectrum provides information about the chemical state of the iron atom in the sample. Isotopes of cobalt Naturally occurring cobalt (Co) is composed of 1 stable isotope, Co. 28 radioisotopes have been characterized with the most stable being Co with a half-life of 5.2714 years, Co with a half-life of 271.8 days, Co with a half-life of 77.27 days, and Co with a half-life of 70.86 days. All of the remaining radioactive isotopes have