Abstract
Raman spectra of brandholzite Mg[Sb~2~(OH)~12~]·6H~2~O were studied, complemented with infrared spectra, and related to the structure of the mineral. An intense Raman sharp band at 618 cm^−1^ is attributed to the SbO symmetric stretching mode. The low‐intensity band at 730 cm^−1^ is ascribed to the SbO antisymmetric stretching vibration. Low‐intensity Raman bands were found at 503, 526 and 578 cm^−1^. Corresponding infrared bands were observed at 527, 600, 637, 693, 741 and 788 cm^−1^. Four Raman bands observed at 1043, 1092, 1160 and 1189 cm^−1^ and eight infrared bands at 963, 1027, 1055, 1075, 1108, 1128, 1156 and 1196 cm^−1^ are assigned to δ SbOH deformation modes. A complex pattern resulting from the overlapping band of the water and hydroxyl units is observed. Raman bands are observed at 3240, 3383, 3466, 3483 and 3552 cm^−1^; infrared bands at 3248, 3434 and 3565 cm^−1^. The Raman bands at 3240 and 3383 cm^−1^ and the infrared band at 3248 cm^−1^ are assigned to water‐stretching vibrations. The two higher wavenumber Raman bands observed at 3466 and 3552 cm^−1^ and two infrared bands at 3434 and 3565 cm^−1^ are assigned to the stretching vibrations of the hydroxyl units. Observed Raman and infrared bands in the OH stretching region are associated with O‐H···O hydrogen bonds and their lengths 2.72, 2.79, 2.86, 2.88 and 3.0 Å (Raman) and 2.73, 2.83 and 3.07 Å (infrared). Copyright © 2009 John Wiley & Sons, Ltd.