Figure 1

Backscattered electron image of a cross-section of the 4 GPa sample extracted from the pressure cell post-experiment and -heating up to ~ 1980 K, ~ 300–400 K above expected melting temperatures. Portions of the thermocouple (TC), rhenium (Re) disks, and bulk sample have been annotated alongside microprobe locations. Results of the microprobe have been tabulated.