A fresh view on the structure and twinning of owyheeite, a rod-polytype and twofold superstructure.

Owyheeite [Cu 0.09 (1) Ag 2.77 (4) Pb 10.23 (4) Sb 10.89 (5) S 28.00 (5) ] crystallizes as a twofold superstructure with P2 1 /n symmetry and pseudo-orthorhombic metrics [a = 8.1882 (3) Å, b = 27.2641 (7) Å, c = 22.8679 (7) Å, β = 90.293 (3)°, V = 5105.0 (3) Å 3 , Z = 4]. Owyheeite is systematically twinned by reflection at (021) or equivalently (021). Twinning is explained by describing a simplified Pmcn archetype structure as polytype built of two kinds of rods, which contact via electron-pair micelles. A procedure of generating hypothetical polytypes by tiling space with partially overlapping equivalent regions is described.