In the course of an investigation of cracks in certain magnesia floors containing the mineral chlorartinite
[Mg2(CO3)(H2O)(OH)]Cl·H2O, the dehydration process of chlorartinite was carried out in high vacuum. The crystal structure of dehydrated chlorartinite
was refined from laboratory X-ray powder diffraction data using the Rietveld method [R3c, a=22.6791(5) Å, c=7.22336(14) Å, V=3217.52(11) Å3, Z=18, Rp=4.13%, Rwp=5.82%]. Dehydrated chlorartinite exhibits the same type of 3D honeycomb zeolite-like crystal structure with large channels as the hydrated form. Compared to the hydrated form, the channels of dehydrated chlorartinite are empty because of the removal of all non-coordinating water molecules with the cell volume shrinking by 4.0%, leading to a more distorted environment of the magnesium atoms.