Fig. 5: Optical and transmission electron microscopy of twinned omphacite grain.

a Omphacitite clast displaying a pervasive network of fractures coated by graphite. Note the location of the omphacite grain shown in (b; thin section photo, plane-polarized light). b Detail of twinned omphacite grain on which TEM was performed (thin section photo, crossed-polarized light). c Selected area of electron diffraction pattern illustrating mirror law of twins along (100), here with the direction [021]*. d TEM bright field image showing numerous planar defects identified as twins on (100). e Carbon-rich inclusions along the twins (arrows).