Micro-Raman spectroscopy applied on oriented crystals of fluoro-edenite amphibole

Fluoro-edenite crystals from Biancavilla, a mineral characterized by various cations in different crystallographic sites, have been studied with Electron Microprobe Analysis (EMPA) and micro-Raman spectroscopy. The spectroscope used in this study was fitted with an optical microscope equipped with two polarizers and a rotating plate with a vernier, allowing precise orientation of the sample. The Raman spectra were acquired after precisely aligning the crystals with respect to the incident laser beam. The spectra recorded are discussed in relation to the chemical data from EMPA analyses. This investigation suggests that a similar methodological approach can be used to discriminate other fibrous amphiboles which can be difficult to identify by conventional techniques.