Reinvestigation of the crystal structure of lautite, CuAsS.

The crystal structure of the mineral lautite (copper arsenic sulfide), CuAsS, previously described as either centrosymmetric [Pnma; Marumo & Nowacki (1964 ▶). Schweiz. Miner. Petro. Mitt.44, 439-454] or noncentrosymmetric [Pna2(1); Craig & Stephenson (1965 ▶). Acta Cryst.19, 543-547], was reinvestigated by means of single-crystal X-ray diffraction. The centrosymmetric structural model reported previously was confirmed, although with improved precision for the atomic coordinates and inter-atomic distances. Lautite shows a sphalerite-derivative structure with a linking of Cu[AsS(3)], As[CuAs(2)S] and S[Cu(3)As] tetra-hedra. All atoms lie on special positions (Wyckoff position 4c, site symmetry m).