Vibrational spectroscopy of natural augelite

The vibrational spectra of natural augelite (Al2(OH)3(PO4)) including the infrared at 298 K and Raman spectra at 298 and 77 K have been obtained and related to the crystallography of the mineral. Bands are identified in terms of the fundamental vibrating units namely PO4, Al2OH and Al3OH. The use of infrared and Raman OH stretching wavenumbers using a Libowitzky type function enabled hydrogen bond distances of 2.96, 2.84 and 2.72 A ° to be estimated. The hydrogen bonds formed by the Al2OH units are weaker than that of the Al3OH units. q 2004 Elsevier B.V. All rights reserved.