OCCURRENCE OF NOBLE-METALS IN ALUMINUM-RICH AND CHROMIUM-RICH OBJECTSIN ORDINARY CHONDRITES AND OF BADDELEYITE (ZRO2) IN A CHROMITE INCLUSION

Platinum group elements (PGE) enrichments are found in Fe-Ni bleds (<1 mum) in Al- and Cr-rich objects in the ordinary chondrites Ste. Margu erite, Forest Vale, Montferre. In Ste. Marguerite, high ZrO2 concentra tions (baddeleyite) are also present in a chromite inclusion. Iridium enrichment in this material compared to its metal content is confirmed by INAA. The widespread occurrence of PGE in Al- and Cr-rich objects, mostly present in H-group chondrites of nearly equilibrated types, mu st be taken into account to understand their conditions of formation.