Raman spectroscopy of the nickel silicate mineral pecoraite - an analogue of chrysotile (asbestos)

The molecular structure of the mineral pecoraite, the nickel analogue of chrysotile of formula Ni3Si2O5(OH)4, was analysed by a combination of Raman and infrared spectroscopies. A comparison is made with the spectra of the minerals nepouite and chrysotile and a synthetic pecoraite. Pecoraite is characterised by OH stretching vibrations at 3645 and 3683 cm(-1) attributed to the inner and inner surface hydroxyl stretching vibrations. Intense infrared bands at around 3288 and 3425 cm-1 are assigned to the stretching vibrations of water strongly hydrogen-bonded to the surface of the pecoraite. The asbestoslike mineral is characterised by SiO stretching vibrations at 979, 1075, 1128 and 1384 cm(-1), OSiO chain vibrations at 616 and 761 cm-1 and Ni-O(H) vibrations at 397 and 451 cm(-1). Copyright (c) 2008 John Wiley & Sons, Ltd.