Evidence for Pervasive Metamorphism on the CR Chondrite Parent Body from Highly Equilibrated CR6 Chondrites Northwest Africa 2994 and Northwest Africa 3100

Among the two dozen or so known unpaired CR chondrite specimens, virtually all have been assigned as petrologic type 2; one example (GRO 95577) is of petrologic type 1. Two other meteorites lacking chon-drules (Tafassasset, LEW 88763) have chemical affini-ties to CR chondrites [1], as do igneous achondrites NWA 011 and pairings [2, 3]. Here we describe two Northwest African specimens that represent rare exam-ples of highly equilibrated (and chemically modified) CR6 chondrites, and which add to the evidence for a relatively large-sized CR parent body capable of sig-nificant and perhaps prolonged internal heating [3].