Atomanordnung und Strukturverfeinerung von Cancrinit

Abstract

X-ray photographs of (Ca, Na)CO3 cancrinites show diffuse satellites with the indices (h k l ± 3/7), The examined crystals from Litchfield, U.S.A., have the space group P63 and the lattice dimensions a = 12.75 Å and c = 5.14 Å.The crystal structure has been determined–independently of all previous structure assumptions–from the relation of the transformation hauyn–cancrinite and refined on three-dimensional data by the least-squares method to R = 0.089.The structure is composed of an ordered Si, Al framework with channels around the threefold axis and the axis 63; the other cations and anions as Na, Ca, H2O, CO3 etc. are enclosed in these channels.