High-Pressure Raman and Infrared Spectroscopic Study of Prehnite

High-pressure Raman and infrared spectra of a natural sample of prehnite, with a chemical composition of Ca₂(Al_0.74,Fe_0.26)₂Si₃O₁₀(OH)₂, are presented. Analyses of the spectra indicate that prehnite undergoes a reversible structural change between 6 and 8 GPa that is most likely associated with a subtle alteration in the orientation and/or deformation of the polyhedra comprising the framework of the structure. At pressures in excess of ~11 GPa, the high-pressure spectra indicate that prehnite undergoes a reversible phase transition involving the collapse of the framework structure.