Fig. 3.

(A) An in diamond anvil cell micrograph of the Fe-dolomite samples used for high-pressure and high-temperature experiments, showing a rhomb-shaped crystal (not heated and used only for laser alignment) and, below it, the sample used for X-ray data collection after heating up to the melting point (2600 K at 43 GPa). (B) Unwarped reciprocal space h0l after pressure release, revealing the nature of the back-transformation of the high pressure polymorph to single crystal dolomite. Despite that the mosaicity increases significantly, the peaks are still indexed with the rhombohedral cell.