Natural abundance solid state 43Ca NMR

43Ca MAS NMR spectra have been collected for 12 solid phases including silicates, carbonates and sulphates. In all cases 43Ca was present at natural abundance, the first time such experiments have been reported. In general the lines are broad and featureless, though in the case of calcite a second order quadrupolar lineshape was observed. Within each class of compounds (silicates, carbonates etc.), the isotropic chemical shift appears to be linearly correlated with the mean CaO bond length of the first coordination shell of calcium, with a similar gradient for all of the classes of compounds studied.