Neutron diffraction was previously used by Seryotkin and coworkers, 2005, to study "the deuterated natrolite, Na1.85Mg0.05Ca0.03[Al2.06Si 2.95O10]•nD2O, compressed in liquid D2O at 0.9 and 1.0 GPa". "At 0.9 GPa, the crystal structure is close to the original natrolite with the same space group Fdd2 and 1% smaller unit cell volume. New water positions are found in addition to the original ones indicating the early stage of natrolite over-hydration. The unit cell volume of high-pressure phase stable at 1.0 GPa is expanded by 5.4 % with respect to initial natrolite. According to structural investigations, HP phase contains 3.5 water molecules pfu. Higher degree of hydration is accompanied by the drastic rearrangement of extra-framework subsystem, water molecules occupying four independent positions" .