Fossil Particle Tracks and Uranium Distributions in Minerals of the Vaca Muerta Meteorite

Science  30 Apr 1965:
Vol. 148, Issue 3670, pp. 629-632
DOI: 10.1126/science.148.3670.629


Fossil tracks of charged particles have been observed in minerals separated from the Vaca Muerta mesosiderite. Irradiation of samples of the meteorite with thermal neutrons in a nuclear reactor, together with measurements of track-length distribution, indicate that some of the tracks result from the spontaneous fission of uranium impurities; others, however, are of different origin. Uranium concentrations, which ranged from about 4000 parts per million in a zircon grain to less than 10-3 parts per million in hypersthene and anorthite, were also measured by irradiating samples with thermal neutrons.