SINGLE-CRYSTAL STRUCTURE REFINEMENT OF ENARGITE [CU3ASS4]

The crystal structure of the room temperature phase of enargite, Cu3As S4, was reinvestigated using a single crystal diffractometer. It is or thorhombic, space group Pmn2(1), [C2v7 No. 31], with a=7.426(1) angstr om, b=6.4521(9) angstrom, c=6.1631(9) angstrom, V=295.3(1) angstrom3, and Z=2. The refinement by full-matrix least-squares led to R1(F)=0.05 89, wR(F2)=0.1475, and S=1.157 for all 930 unique reflections and R1(F )=0.0471 for 768 reflections with F(o)>4sigma(F(o)). In the present wo rk, the atomic positional parameters of Cu3AsS4, established more than twenty years ago, have been determined more accurately. Physically me aningful thermal parameters for all atoms are also reported.