A refinement of the crystal structure of covellite, CuS

The crystal structure of covellite has been refined, based on counter intensity data, to R=3.9,°-6', using a crystal from Kosaka mine: P63/mmc, a=3.976(1), c=16.382(5)'\, Z=6. The structure proposed by Oftedal (Zeits. Krist., 83, 9-25, 1932) was confirmed. The S-S distance of the S2 groups in the structure is 2.086(7)'\, the Cu-S distance in the CUS3 triangles 2.1915(4)'\, and the mean Cu-S distances in the CUS4 tetrahedra 2.313'\. The highly perfect cleavage characteristic of covellite may well be ascribed to the strong Cu-S bonds in the CuS3 triangles which form, sharing corners, con-tinuous sheets parallel to (00l)