Iron oxide, have the ferrous oxide FeO, two iron oxide FeO2, trioxide Fe2O3, Fe3O4, ferrous oxide and say a iron oxide, black powder, melting point for 1369 + 1 ℃, relative density of 5.7, dissolved in acid, insoluble in water and alkali solution. Highly stable, easy to be oxidized to three oxidation 2 iron; In the air heating will quickly be oxidized to four oxidation SanTie. In isolation of the air condition, ferrous oxalate obtained by heat. Mainly used to make glass pigment. 3 oxidation 2 iron is palm red or black powder, commonly known as the iron oxide red, melting point for 1565 ℃, relative density of 5.24. In nature to form existence, have both sexes hematite, and acid Fe () function generation Ⅲ salt, and alkali role [Fe (OH) to 6] 3- In alkali medium have certain reducing, can be strong oxidizer have oxidation. 3 oxidation 2 iron insoluble in water, also do not work with water. Burning ferrous sulfate, oxalic acid, iron, oxygen ferric oxide can be made, it also through in the air to making calcined pyrite mine. It used to do pigment, polish, catalysts and red, etc. Four oxidation SanTie for black crystal, heated to a melting point and decomposition, the relative density of 5.18, has the very good magnetic. It is in the main components of the magnetite natural condition, wet air oxidation in easy into three oxidation 2 iron. Insoluble in water, soluble in acid.