Mossbauer spectroscopic studies of soils are generally centered around
the characterization of Fe3+ oxides, making use of distinctive magnet
ic properties of the different oxides and the high sensitivity of the
technique for magnetically ordered phases. Most work on clays and clay
minerals, in contrast, focuses on the determination of the oxidation
state of iron, iron structural site occupancies and distortions, and t
he transformations that take place during clay firing.