Combined use of photoacoustic spectroscopy and differential thermal analysis in mineralogical analysis

Abstract

The ultraviolet-visible and near-infrared absorption spectra of minerals can be conveniently studied by photoacoustic spectroscopy. The spectra show considerable overlap, which limits their value for qualitative mineralogical analysis. However, the changes in mineral PA spectra on heating, which correspond mainly to dehydration or dehydroxylation reactions, changes in bonding of iron or oxidation of Fe(II), show considerable potential for the identification of the minerals themselves and of the processes that take place during their alteration. The changes are discussed briefly for a wide range of common minerals, and the analytical potential of this approach is critically appraised.