After calcination, the lineshape of the spectrum was much broader, consistent with the significant degree of structural disorder in meta-kaolinite. Multiple overlapping resonances in the spectrum acquired at B0 = 9.4 T (Figure ) were observed at δobs = 55.5 ppm attributed to 4-fold Al, δobs = 24.0 ppm attributed to the mid-range Al resonance and the shoulder at δobs = 9.0 ppm attributed to 6-fold Al . Minor contributions from the muscovite and K-feldspar impurities to the measured spectrum were expected to be similar to these minerals' resonances in the as-received clay's spectrumfrom previous studies on heating muscovite and K-feldspar The quantitative results of the deconvolution of the 27 Al MAS NMR spectra showed (Figure ) that in the low-Fe clay, the vast majority (>93%) of Al was in 6-fold coordination. Fittings and fitting parameters are shown in Figure and Information. Good agreement was obtained between the values obtained from the spectra of both field strengths.