What color is your salt? The anhydrous inorganic copper salts (ie CuSO4) I've seen are very pale, nearly colorless. The hydrated salts, and copper salts with organic ligands, are usually brilliant colors (eg the emerald color of CuCl2.2H2O, the cobalt blue of CuSO4.5H2O, the blue of Cu(AcAc)2, etc).