High-resolution solid-state ²⁷ Al NMR spectroscopy of Mg-rich vesuvianite

High-resolution solid-state ²⁷Al nmr spectroscopic data indicate that the pentahedrally coordinated B site of vesuvianite is at least partially occupied by Al in Fe-poor, Mg-rich vesuvianites. The isotropic ²⁷Al chemical shifts are 41.1 (±0.5) ppm for the 5-coordinated site and 9.0 and 2.5 (± 1) ppm for the octahedrally coordinated A and AlFe sites, respectively. These results were obtained using a recently developed technique based on observing the ±(3/2,1/2) satellite transitions of nuclides with spin I = 5/2, which provides a substantial increase in resolution relative to traditional massnmr examination of the central transition. The ²⁹Si nmr spectra of the same samples contain a broad resonance at -80 ppm.