Origin of graphitic carbon and pentlandite in matrix olivines in the Allende meteorite

Matrix olivines in the Allende carbonaceous chondrite are believed to have formed by condensation processes in the primitive solar nebula. However, tr ansmission electron microscope observations of numerous matrix olivines sho w that they contain abundant, previously unrecognized, nanometer-sized incl usions of pentlandite and poorly graphitized carbon. Neither of these phase s would have been stable at the high-temperature conditions required to con dense iron-rich olivine in the solar nebula. The presence of these inclusio ns is consistent with formation of the olivines by parent body processes th at involved overgrowth of fine-grained organic materials and sulfides in th e precursor matrix materials.