Thermal and Mossbauer studies of iron-containing hydrous silicates. III. Cronstedtite
Review articleOpen access
1981/03/16 Full-length article DOI: 10.1016/0040-6031(81)80039-1
Journal: Thermochimica Acta
AbstractThe thermal transformations of a disordered polycrystalline cronstedtite have been studied in both oxidising and reducing atmospheres by thermal analysis, X-ray powder diffraction, IR and Mossbauer spectroscopy. After low-temperature loss of surface adsorbed water, hydroxyl water is lost by internal oxidation of Fe2+ to Fe3+ under both oxidising and reducing conditions. Removal of further hydroxyl water from this oxycronstedtite results in the progressive formation of an intermediate phase containing both iron and silicon in intimate association; when formed under oxidising conditions this intermediate adopts a hexagonal structure which subsequently transforms to hematite. Reducing atmospheres favour the formation of a cubic intermediate which subsequently transforms to an olivine, and, on further reduction, to iron metal and cristobalite.
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