primitive achondriteAn achondrite that is almost like a chondrite in composition with an age similar to the primordial chondrites. Primitive achondrites, which belong to the so-called PAC group, are residues from partial melting that took place on small parent bodies having chondritic compositions. Following an initial heating phase, they were quickly cooled to become geologically inactive. Related category METEORS AND METEORITESAlso on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |