Single crystals of CaF 2 in the PbCl 2 structure were grown at high pressure in a molten calcium hydroxide flux, and the structure was refined by single crystal X-ray diffraction ( Pnma, a=6.018(2) Å, b=3.614(1) Å, c=7.023(2) Å). Calcium is in nine-coordination in this structure, with Ca–F distances range from 2.317 to 2.774 Å. The two distinct fluorine atoms are in four and five coordination with calcium. Both the ambient pressure fluorite phase and the high pressure phase of CaF 2 have calcium in a close-packed configuration, cubic in fluorite and hexagonal in the PbCl 2 phase. This allows a simple comparison of the Ca arrays between the two phases. It is found that the close-packed array in the PbCl 2 phase is contracted along a and b by 4.7 and 6.6%, respectively, and elongated along c by 4.8%, relative to the close-packed array in fluorite.