Laser Raman spectroscopic measurements of water in unexposed glass inclusions

A method is proposed for determining the water concentration in silicate melt inclusions (MI) by confocal micro-Raman spectroscopy, without exposing the inclusions for measurement (a prerequisite of all previous methods). The latter is important for extremely water-rich MI (e.g., those in evolved granites and pegmatites), which would loose H2O on exposure. Furthermore, this technique permits determination of the water concentration in a single MI. We use a comparative technique, determining the total water content of a sample against a reference glass of known water content. Because this process is non-destructive it does not preclude the subsequent use of other analytical techniques.