The role of SIMS in the investigation of the complex crystal chemistry of mica minerals

A full characterisation of micas requires complete chemical analysis, including the determination of light elements, combined with Mössbauer spectroscopy or any technique suitable for the determination of ferric and ferrous iron contents, and crystal structural analysis (SCXRD). In this context, the SIMS technique is essential for a deeper understanding of the crystal chemistry of mica owing to its capability of precise and accurate quantification of light elements, i.e., H, Li, B, F, .... The role of SIMS is here outlined in the investigation of the complex crystal structure of mica, with new data on a set of volcanic samples, and their comparison with those from literature on trioctahedral micas from volcanic areas of Southern Italy. The importance of SIMS micro-spot (in-situ) analysis is here emphasized as a modern approach to gain insight into physico-chemical processes that affect grain-to-grain or intra-grain chemical variability in complex mineral structures.