Iodine-129 in Terrestrial Ores

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Science  23 Jul 1971:
Vol. 173, Issue 3994, pp. 327-328
DOI: 10.1126/science.173.3994.327


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.