STUDYING IRON-OXIDES IN SOILS BY SAMPLING THERMOMAGNETIC ANALYSIS

Sampling differential thermomagnetic analysis permits identification o f goethite alpha FeOOH, hematite alpha Fe2O3, lepidocrocite gamma FeOO H, ferrihydrite 5Fe(2)O(3) . 9H(2)O, and feroxyhyte delta FeOOH in a s oil. Besides thermodynamically stable goethite and hematite, unstable iron hydroxides-lepidocrocite, ferrihydrite, and feroxyhyte-are presen t in soils of humid regions. They are likely to have been formed recen tly and to have not had time to convert into thermodynamically stable forms. The presence of various unstable iron hydroxides testifies to t he different ways of iron oxidogenesis depending on physicochemical an d biochemical conditions in the soil.