Josephinite: A terrestrial alloy with radiogenic xenon-129 and the noble gas imprint of iron meteorites.

Analyses of noble gases released by stepwise heating of Josephinite reveal two radiogenic components, radiogenic 129Xe≈ 1 × 10-12ccSTP/g and radiogenic 40Ar≈1×10-6ccSTP/g, and the following components of trapped noble gases: He with 3He/4He≈4×10-5, Ne with 20Ne/22Ne = 10.5, Ar with 40Ar/36Ar = 3×102, and Kr and Xe with isotopic compositions similar to those observed in iron meteorites. The excess of 40Ar and literature values of K in bulk Josephinite yield an apparent K-Ar age of ≈4.6×109 years.