Cobalt Sesquioxide, Co₂O₃

Cobalt Sesquioxide, Co₂O₃, results when cobalt nitrate is gently heated to 180° C. It is a black, amorphous powder, of density 5.18. Hydrogen begins to reduce it at 182° C. It may be regarded as the cobalt salt of cobaltous acid, namely, cobaltous cobaltite, CoCoO₃.