The crystal structure of glauberite, CaNa2(SO4)2

Abstract

The crystal structure of glauberite has been determined from precession data taken on a spherical single crystal. The mineral is monoclinic and its space group is C2h6–C2/c. There are four molecules per unit cell. The parameters, determined by diffractometer data and refined by the least-squares method, are: a = 10.158 Å, b = 8.333 Å, c = 8.551 Å, β = 112°20′. The SO4−− tetrahedra are “regular”. Ca atoms are surrounded by eight O atoms placed at the corners of an irregular square antiprism. The Na atoms, binding seven oxygens, form very distorted octahedra with one centered face. The final discrepancy index R is 9.0%.