Raman and infrared spectroscopic study of the molybdate-containing uranyl mineral calcurmolite

Raman and infrared spectra of calcurmolite were recorded and interpreted from the uranium and molybdenum polyhedra, water molecules and hydroxyls point of view. U-0 bond lengths in uranyl and Mo-O bond lengths in M006 octahedra were calculated and O-H... 0 bond lengths were inferred from the spectra. The mineral calcurmolite is characterised by bands assigned to the vibrations of the U02 units. These units provide intense Raman bands at 930, 900 and 868 and 823 cm-'. These bands are attributed to the anti-symmetric and symmetric stretching modes of the U02 units, respectively. Raman bands at 794, 700, 644, 378 and 354 cm-1 are attributed to vibrations of the M004 units. The bands at 693 and 668 cm-1 are assigned to the anti-symmetric and symmetric Ag modes of the terminal M02 units. Similar bands are observed at 797 and 773 cm-' for koechlinite and 798 and 775 cm-1 for lindgrenite. It is probable that some of the bands in the low wavenumber region are attributable to the bending modes of M02 units. Copyright (c) 2008 John Wiley & Sons, Ltd.