Isotopes of platinum
Naturally occurring platinum (Pt) consists of five stable isotopes (Pt, Pt, Pt, Pt, Pt) and one very long-lived (half-life 6.50×10 years) radioisotope (Pt). There are also 34 known synthetic radioisotopes, the longest-lived of which is Pt with a half-life of 50 years. All other isotopes have half-lives under a year, most under a day. All isotopes of platinium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.