THE CRYSTAL STRUCTURE OF BERTHIERITE, FESB2S4

The general arrangement of atoms in berthierite had been suggested in an earlier publication by solving the Patterson function Pxy, with the aid of the minimum function M8xy. In this paper a report is given of the refinement of the structure. The intensities were measured by the M.I.T. modification of the Dawton method, and the resulting F2s were placed on an absolute basis by Wilsons method. The structure was refined by the use of successive differential Fourier syntheses. The final structure has a small residual factor and neatly reproduces the Patterson projection. In the structure of berthierite each Sb atom is evidently bonded to 3 S atoms at distances of about 2.5A. These SbS3 groups share S atoms to form two nonequivalent SbS2 Chains parallel to the c axis. The Fe atoms are surrounded by 6 S atoms in approximately octohedral arrangement at distances of about 2.5A. This is about the expected distance for ionic Fe-S bonds. The structure can therefore probably be regarded as Fe SbS22.