Ca10(CrVO4)6 (CrVIO4), a Disordered Mixed-Valence Chromium Compound Exhibiting Inversion Twinning.

Samples containing 46, 49, and 51 wt.% Cr2O3 (primary crystallization field in the CaO—Cr2O3 system) in a mixture of CaCO3, CrO3, HNO3, and H2O are slowly heated to 1173 K and show the presence of Ca5(CrO4)3OH and CaCrO4.