gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1970.037.292.01 Replacement of OH by OD in Layer Silicates, and Identification of the Vibrations of These Groups in Infra-Red Spectra Russell J. D. Farmer V. C. The Macaulay Institute for Soil Research, Craigiebuckler, Aberdeen Velde B. Laboratoire de Pétrographie, Tours 16-26, Faculté des Sciences de Paris, 9 Quai Saint Bernard, Paris 5ème 12 1970 37 292 869 879 24 11 1969 Copyright © 1970, The Mineralogical Society 1970 Summary

Conditions necessary for exchange between lattice OH groups and D2O in expanding layer silicates are reported. From spectral changes in the 200–1200 cm−1 region resulting from this exchange, in-plane librations of OH co-ordinated to (A1A1), (A1Mg), (A1Fe3+), and (MgMgMg) have been identified in montmorillonite, beidellite, saponite, hectorite, and vermiculite. Both in-plane and out-of-plane librations have been identified for pyrophyllite and celadonite, from comparison of synthetic specimens containing OD with natural or synthetic OH forms. Comparison of hydrogen and deuterium forms of Mg- and Ni-talcs leads to the identification of translational and librational OH vibrations.