The crystal structure refinement of a natural mordenite

Abstract

The crystal structure of natural mordenite from Elba (Italy) with chemical formula [formula omitted] was refined in its hydrated form up to a wR value of 5.2%. Systematic absences were consistent with the Cmcm space group but the asymmetry of the extraframework ions indicated as more probable the acentric subgroup Cmc21. Consequently the atom 08 is no longer set on an inversion center and the T –O8–T angle is not constrained to 180°. The Si/Al distribution is partially ordered, with an enrichment of Al in the tetrahedra of the four-membered ring. All Ca ions are localized in a eight-coordinated site; K ions alternate with water molecules in a six-coordinated site. © by R. Oldenbourg Verlag