ABSTRACT

Many samples of bulk and sieved fractions of Ambapur Nagla and other stone meteorites as well as acid insoluble residues of Sikhote Alin iron meteorite have shown isotopically anomalous ratios for ¹⁹⁰Os/¹⁸⁴Os as measured by RNA. Both positive and negative deviations, relative to terrestrial standard, are seen. The largest values, found in bulk samples are 60% enrichment of ¹⁹⁰Os in Efremovka and 50% depletion in Allende. The number of anomalous cases are very few (19–22%) as compared to the normal cases. Apparently isotopically anomalous osmium is contributed from interstellar or extraneous matter in both stone and iron meteorites.