The Raman and IR spectra of monoclinic naturally occurring raspite, a-PbWO 4 (space group P2 1 /a) were measured; it is irreversibly transformed to the tetragonal stolzite, b-PbWO 4 , by heating to 450 • C, and this process was followed by Raman spectroscopy. Assignments of fundamental modes are proposed. New data are also presented on single crystals of stolzite (space group I4 1 /a), and it is shown that raspite and stolzite can easily be distinguished by their Raman spectra. We also present Raman and IR spectroscopic data on natural and synthetic studtite, UO 4 ·4H 2 O, and its synthetic dehydration product metastudtite, UO 4 ·2H 2 O, the only two naturally occurring peroxide-containing minerals, and on partially deuterated synthetic forms of these materials. Assignments of fundamental modes are proposed and both TGA and DSC data are presented for studtite.

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