STRUCTURAL AND MORPHOLOGICAL EVIDENCE OF THE IMPACT-INDUCED DEVELOPMENT OF DIAMOND AFTER GRAPHITE IN THE NOVO-UREI METEORITE

Abstract

The diamond obtained from the Novo-Urei meteorite by acid leaching was examined using a combination of X-ray diffractometry (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The micromorphology, orientation of the crystal structure relative to crystal faces (crystallometry of developed crystal surfaces), and other structural features of the diamond particles suggest that they have been formed by means of martensite transformation of graphite crystals under the effect of shock metamorphism. The fact that impact diamonds from the Novo-Urei meteorite belong to a single phase and have little defects points to their origin in the region of high impact pressures and residual temperatures, i.e., as a result of a large-scale impact event.