Calcium Chromite, CaCrO₄ or CaO.Cr₂O₃

Calcium Chromite, CaCr₂O₄ or CaO.Cr₂O₃, may be obtained as an olive-green crystalline powder by heating together potassium dichromate and calcium chloride, and extracting with concentrated hydrochloric acid. On precipitating a solution of chrome alum and a calcium salt with potassium hydroxide in excess, a green insoluble compound, corresponding in composition with the formula 2CaO.Cr₂O₃.xH₂O, is formed. It is less stable than the former compound, being readily oxidised to chromate by heating in air. By heating chromium sesquioxide and calcium oxide together in the electric furnace, hard green crystalline plates of density 4.8 and composition 4CaO.Cr₂O₃ are formed. They are decomposed by water.