Iodine-129 in terrestrial ores

Abstract

Xenon extracted from natural iodyrite (silver iodide) from Broken Hill, New South Wales, Australia, contains excess xenon-129 from the in situ decay of naturally occurring iodine-129 and excess xenon-128 from neutron capture on iodine-127. On the basis of the amount of radiogenic xenon-129, it is estimated that, prior to the nuclear age, terrestrial iodine contained an equilibrium ratio of iodine-129 to iodine-127 of between 3.3 x 10(-15) and 2.2 x 10(-15).