Stannous tungstate, (Formula presented) crystallizes in the low-temperature α and high-temperature β phases. (Formula presented) powders were prepared by heating an equimolar mixture of SnO and (Formula presented) either in vacuum or in argon atmosphere at 600 °C for 15 h. The high-temperature β phase was obtained as metastable at room temperature after heating the mixture at 800 °C and rapid quenching. In addition to x-ray-diffraction studies, (Formula presented) Mössbauer and Raman spectroscopies were used as “local” probes for the characterization of the phase structures in the semiconducting and gas-sensitive powders. The composition of the powders was measured by the energy-dispersive spectroscopy of x rays. Mössbauer spectroscopy, especially, as a very local probe for tin atoms gave valuable information of small extra phase(s) in the α- and (Formula presented) powders originating in the oxidation of (Formula presented) ions in the (Formula presented) structures into the (Formula presented) form. The (Formula presented) Mössbauer doublet from both α and β phases showed some asymmetry not published before. The asymmetry was possible to relate to the Goldanskii-Karyagin effect with calculations based on published results for the atomic positions and thermal displacement parameters in the x-ray temperature factor of the α- and (Formula presented) structures. Raman spectra are given together with peak frequencies from a curve fit for both α- and β-phase powders. The symmetries and selection rules of the normal modes at the center of the Brillouin zone are also given for both α and β phases. © 1998 The American Physical Society.