Ca-, Al-rich refractory inclusions and Pt-metal nuggets in the Ningqiang carbonaceous chondrite

Petrography and mineral chemistry of Ca, Al-rich inclusions of Ningqiang carbonaceous chondrite are studied and the highly Re-Os fractionated Pt-metal nuggets in it is discovered. The refractory inclusions are classified into melilite-spinel-rich, and spinel-pyroxene-rich types. The former probably crystallized from melts, while the latter could be aggregates of the nebular condensates. The strong fractionation between Re and Os suggests a pro-solar origin of the Pt-metal nuggets, which probably experienced various processes of formation and evolution before being captured by the refractory inclusions as indicated by the depletions of W and Mo.