Abstract
The crystal structure of covellite has been refined, based on counter intensity data, to R=3.9%, using a crystal from Kosaka mine: P63⁄mmc, a=3.976(1), c=16.382(5)Å, 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)Å, the Cu–S distance in the CuS3 triangles 2.1915(4)Å, and the mean Cu–S distances in the CuS4 tetrahedra 2. 313Å. 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, continuous sheets parallel to (001).
