Zinc Dichromate, ZnCr₂O₇

The trihydrate, ZnCr₂O₇.3H₂O, is difficult to crystallise from its solutions, but has been prepared by evaporating a solution of zinc carbonate in chromic acid under reduced pressure over sulphuric acid. It crystallises in hygroscopic, transparent orange crystals that dissolve easily in water. Boiling water only affects them slightly.

Dark red deliquescent crystals of the trichromate, ZnO.3CrO₃.3H₂O, and the salt, ZnCr₂O₇.2Hg(CN)₂.7H₂O, have been prepared.