Since the discovery of excess Xe129 in stone meteorites [Reynolds, 1960a], enough striking examples of the effect have been found [Reynolds, 1960b; Zähringer and Gentner, 1961] to establish beyond reasonable doubt that excess Xe129 is due to radioactive decay of extinct I129. The usual interpretation has been that the I129 decay took place in situ, so that the ‘formation interval’ between the nuclear event that produced the I129 and the formation (or cooling) of a meteorite can be related to the Xe129/I127 ratio for the stone and to the 17 m.y. half‐life of I129. Some authors [Eberhardt and Geiss, 1960; Zähringer and Gentner, 1961], questioning this interpretation, have suggested that the I129 decay took place in a primordial planetary nebula where abnormal xenon may have been stored for long periods before meteorite formation. A crucial test of the first interpretation is whether the excess Xe129 is associated with the iodine‐bearing minerals in a meteorite.

No abstract

No abstract

The relative isotopic composition of tin extracted from 22 terrestrial samples, 4 iron meteorites, and the metal phase of 1 mesosiderite has been measured in a solid source mass spectrometer. No differences greater than 1% were found in the abundances of masses 116 to 124 or greater than 5% for masses 112 and 114 in any of these samples with respect to a tin standard.