The crystal structure of anhydrite (CaSO 4 )

Abstract

The structure of anhydrite (CaSO4) was determined by Wasastjerna in 1925 and a somewhat different solution for its structure was described by Dickson and Binks in 1926. Redetermination of the structure using Fourier and least-squares refinements of one projection yields a result very similar to that favoured by Wasastjerna. The alternative structure gives markedly poorer agreement between observed and calculated intensities. Details of the structure of anhydrite were first investigated by Wasastjerna (1925) using powder photograph and spectrometer methods. Eighty-five different types of structure were considered and it was shown that only two structures (in the present work denoted as A and B) were possibly correct. These two structures are closely related to one another but differ by the translation of atom groups in the direction of one cell axis by 0.