The crystal structure of tetrahedrite, Cu12Sb4S13

Tetrahedrite, Cu 12 Sb 4 S 13 , has a curious superstructure based on the sphalerite arrangement. This structure was proposed by P auling and N euman in 1934 on the basis of a limited number of measured intensities. Least-squares refinement in this study reduced an initial disagreement index of 27.9% to 3.9% and thus confirmed the correctness of the structure. The absolute configuration of the structure was established. Tetrahedrite contains two sorts of copper atoms. A first type is coordinated by four sulfur atoms at 2.342 Å which form a nearly regular tetrahedron. The second type of copper atom is in an unusual triangular coordination, being bonded only to one sulfur atom at 2.234 Å and two at 2.272 Å. This group is planar, and the copper atom has a highly anisotropic thermal motion. The antimony atom is bonded to three sulfur atoms at 2.446 Å, which form bond angles of 95° 8′, but has six additional sulfur neighbors at the van der Waals distance of 4.033 Å. The polyhedra are linked in a complex manner which is discussed in detail.