Structural Analysis of a Series of Oxygen-coordinated Al(III) in Aluminosilicate Minerals by X-Ray Absorption and NMR Spectrometries

Al K X-ray Absorption Near-Edge Structure (XANES) spectra of a series of aluminosilicate minerals were analyzed by DV-Xα MO method. Aluminosilicate minerals in nature contain various oxygen-coordinated Al(III), e.g. four-, five- and six- (1:1), and six-fold. In this study, the Al K XANES spectra of anorthite [CaAl2Si2O8], andalusite [Al2SiO5] and kaolinite [Al2Si2O5(OH)4] were measured and analyzed in terms of the electron transition probabilities. Their coordination structures and bond characters were discussed. The results were also compared with those of NMR measurements.