Eisen(II)-carbonat als Ausgangsmaterial zur Herstellung von röntgenamorphem Eisen(III)-hydroxid sowie von γ-FeOOH und α-FeOOH

X-ray amorphous iron(III) hydroxide is formed on treating FeCO₃ with H₂O₂. However, oxidation of freshly precipitated FeCO₃ by means of air yields — in the absence of foreign cations — γ-FeOOH and α-FeOOH. The latter is obtainable in the pure state provided that FeCO₃ is air-oxidised in alkaline medium (excess of Na₂CO₃).