Stable Silicon Isotopes - Si Iisotopes | Nominal mass | Accurate mass | % Natural abundance | Chemica form | Enrichment available % | | 28 Si | 27.9769271(7) | 92.23(7) | metal, fluoride | 99+ | | 29 Si | 28.9764949 (7) | 4.67 (5) | metal, oxide | 95 - 99+ | | 30 Si | 29.9737707(7) | 3.10 (5) | metal, fluoride | 99+ | |