 Platinum has six naturally occurring isotopes : 190Pt , 192Pt , 194Pt , 195Pt , 196Pt , and 198Pt . The most abundant of these is 195Pt , comprising 33 @.@ 83 % of all platinum . It is the only stable isotope with a non @-@ zero spin ; with a spin of 1 / 2 , 195Pt satellite peaks are often observed in 1H and 31P NMR spectroscopy ( i.e. , Pt @-@ phosphine and Pt @-@ alkyl complexes ) . 190Pt is the least abundant at only 0 @.@ 01 % . Of the naturally occurring isotopes , only 190Pt is unstable , though it decays with a half @-@ life of 6 @.@ 5 × 1011 years , causing an activity of 15 Bq / kg of natural platinum . 198Pt can undergo alpha decay , but its decay has never been observed ( the half @-@ life is known to be longer than 3 @.@ 2 × 1014 years ) ; therefore , it is considered stable . Platinum also has 31 synthetic isotopes ranging in atomic mass from 166 to 202 , making the total number of known isotopes 37 . The least stable of these is 166Pt , with a half @-@ life of 300 µs , whereas the most stable is 193Pt with a half @-@ life of 50 years . Most platinum isotopes decay by some combination of beta decay and alpha decay . 188Pt , 191Pt , and 193Pt decay primarily by electron capture . 190Pt and 198Pt have double beta decay paths . 
