Variable ¹⁹⁰Os/¹⁸⁴Os ratio in acid residues of iron meteorites

Abstract

In residual materials obtained on dissolution of iron meteorites in 2M H₂SO₄, the ratio of ¹⁹⁰Os/¹⁸⁴Os has been measured by radiochemical neutron activation analysis. Most residues have a normal isotopic ratio (to within ±2%). However, in some residues both positive and negative deviations in the isotopic ratio are seen. The most spectacular deviations are in the insoluble fragments (nuggets) from Sikhote Alin iron meteorite where the ¹⁹⁰Os/¹⁸⁴Os ratio is about 50% of the normal value. The new results confirm our earlier observations that iron meteorites contain pre-solar grains.