Quantification and mapping of Fe valence inside partly vermiculitized biotite grain

Abstract

Spatial distribution in chemical compositions and Fe valence states within weathered biotite grain were examined through microanalytical techniques of FE-EPMA and μ-XAFS. Different packets of vermiculite-enriched and biotite-dominant were found to be interstratified at each interval of ~ several μm, there was no difference in Fe-K XANES spectra obtained from those respetive packets. These results suggest that vermiculitization is not necessarily associated with layer charge reduction in weathered biotite.