Characterisation of contact twinning for cerussite, $$\hbox {PbCO}_3$$, by single-crystal NMR spectroscopy

Cerussite, $$\hbox {PbCO}_3$$ , like all members of the aragonite group, shows a tendency to form twins, due to high pseudo-symmetry within the crystal structure. We here demonstrate that the twin law of a cerussite contact twin may be established using only $$^{207}$$ Pb-NMR spectroscopy. This is achieved by a global fit of several sets of orientation-dependent spectra acquired from the twin specimen, allowing to determine the relative orientation of the twin domains. Also, the full $$^{207}$$ Pb chemical shift tensor in cerussite at room temperature is determined from these data, with the eigenvalues being $$\delta _{11} = (-2315\pm 1)$$ ppm, $$\delta _{22} = (-2492 \pm 3)$$ ppm, and $$\delta _{33} = (-3071 \pm 3)$$ ppm.