THERMODYNAMICALLY UNSTABLE IRON HYDROXIDES IN SODDY-PODZOLIC AND BROWN FOREST SOILS

Thermodynamically unstable iron hydroxides (lepidocrocite, ferrihydrit e, ferroxyhite) are shown to form in those soddy-podzolic and brown fo rest soils that are enriched in easily weatherable iron-containing min erals and develop in semihydromorphic conditions. Active formation of unstable hydroxides (especially, ferroxyhite) is noted for the concret ions in the upper horizons of podzolic soils. The presence of these un stable minerals in soils should be taken into consideration while solv ing genetic and classification problems.