Primitive lead from iron meteorites

Abstract

Isotopic analyses show that the Odessa iron meteorite, as well as the Toluca iron meteorite, contains the primeval lead which Patterson, Bbown, Tilton and Inghram (1953) first discovered in troilite from the Canyon Diablo and Henbury iron meteorites. However, significant variations of isotopic ratios occur within all these meteorites. Lead from the samples of Odessa meteorite has unusual amounts of Pb 206 which increase with the bismuth content. Nuclear synthesis may account for the differences in isotopic composition found in different samples of this meteorite. There is no suggestion of transitions towards the radiogenic type of lead observed in some iron meteorites (including Toluca). Within the limits of error, the sample of nickel-rich ataxite Pinon contained no detectable lead. This result corroborates independent measurements which indicate that this type of iron meteorite contains at the most only a few hundredths' ppm of lead. Octahedrites, on the other hand, may contain as much as 0–25 ppm.