ts as hydroxides followed by oxidation by aeration where careful control of the pH determines the oxide produced.[5]Reduction of Fe2O3 with hydrogen:[13][14]3Fe2O3 + H2 → 2Fe3O4 +H2OReduction of Fe2O3 with CO:[15]3Fe2O3 + CO → 2Fe3O4 + CO2Production of nano-particles can be performed chemically by taking for example mixtures of FeII and FeIII salts and mixing them with alkali to precipitate colloidal Fe3O4.The reaction conditions are critical to the process and determine the particle size.[16]Iron(II) carbonate can also be thermally decomposed into Iron(II,III):[17]3FeCO3 → Fe3O4 + 2CO2 + COReduction of magnetite ore by CO in a blast furnace is used to produce iron as part of steel production process:[4]Fe 3 O 4 + 4 CO ⟶ 3 Fe + 4 CO 2 {\displaystyle {\ce ((Fe3O4}+ 4CO -> {3Fe}+ 4CO2))}Controlled oxidation of Fe3O4 is used to produce brown pigment quality γ-Fe2O3 (maghemite):[18]2 Fe 3 O 4 ⏟ magnetite + 1 2 O 2 ⟶ 3 ( γ − Fe 2 O 3 ) ⏟ maghemite {\displaystyle {\ce {\underbrace{2Fe3O4}_{magnetite}+ {1/2O2}