Melting of rhombohedral phosphorus was also studied by in-situ synchrotron X-ray diffraction using MAX80 (at 3.9 and 4.5 GPa) and SPEED-1500 (at 6.9 GPa) multianvil presses. The results are shown in Fig. (solid and open squares correspond to rhombohedral solid phase and liquid, respectively) and are in excellent agreement with the data obtained by the electrical resistivity measurements.