Infrared and low-temperature micro-Raman spectra of the OH stretching vibrations in Cummingtonite

A simple structural model is developed of the effect of cation occupancy on the OH stretching bands of Cummingtonite. The observed broadening of the unresolved Raman bands at low temperatures, as well as the variation in the inter- and intra-ionic force constants of the OH group, is consistent with the model. These results confirm earlier assignments of the vibrational spectra of amphiboles in the OH stretching region.