The mineral xonotlite Ca6Si6O17(OH)(2) is a crystalline calcium silicate hydrate which is widely used in plaster boards and in many industrial applications. The structure of xonotlite is best described as having a dreierdoppelketten silicate structure, and describes the repeating silicate trimer which forms the silicate chains, and doppel indicating that two chains combine. Raman bands at 1042 and 1070 cm(-1) are assigned to the SiO stretching vibrations of linked units of Si4O11 units. Raman bands at 961 and 980 cm(-1) serve to identify Si3O10 units. The broad Raman band at 862 cm(-1) is attributed to hydroxyl deformation modes. Intense Raman bands at 593 and 695 cm(-1) are assigned to OSiO bending vibrations. Intense Raman bands at 3578, 3611, 3627 and 3665 cm(-1) are assigned to OH stretching vibrations of the OH units in xonotlite. Infrared spectra are in harmony with the Raman spectra. Raman spectroscopy with complimentary infrared spectroscopy enables the characterisation of the building material xonotlite. (C) 2012 Elsevier Ltd. All rights reserved.