Potassium Magnesium Chromate, K₂CrO₄,MgCrO₄

Potassium Magnesium Chromate, K₂CrO₄.MgCrO₄.6H₂O, crystallises from the mixed solutions of its constituent salts at -10° C. It deposits as small, lemon-yellow crystals which effloresce and are monoclinic. It can be crystallised out up to 15° C., but is apparently unstable even at 10° C. and changes slowly into the dihydrate. The change is more rapid at 120° C. The dihydrate forms light yellow prismatic crystals which dissolve in water without decomposition; it can be crystallised from very concentrated solutions.