Isotopes of iron
Natural iron (26Fe) consists of four stable isotopes: 5.85% 54Fe, 91.75% 56Fe, 2.12% 57Fe and 0.28% 58Fe. There are 28 known radioisotopes and 8 nuclear isomers, the most stable of which are 60Fe (half-life 2.62 million years) and 55Fe (half-life 2.7562 years).