High Quality Content by WIKIPEDIA articles! Naturally occurring tungsten (atomic symbol W) consists of four stable isotopes (182W, 183W, 184W, and 186W) and one isotope, 180W, with an extremely long half-life of 1.8 ± 0.2 Ea (1018 years). On average, two alpha decays of 180W occur per gram of natural tungsten per year.