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 P21/n symmetry and pseudo-orthorhombic metrics [a = 8.1882 (3) angstrom, b = 27.2641 (7) angstrom, c = 22.8679 (7) angstrom, beta = 90.293 (3)degrees, V = 5105.0 (3) angstrom(3), Z = 4]. Owyheeite is systematically twinned by reflection at (021) or equivalently (0 (2) over bar1). 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.

Automated summary

Owyheeite crystallizes as a twofold superstructure with P21/n symmetry and pseudo-orthorhombic metrics. It is systematically twinned by reflection at (021) or equivalently (0 (2) over bar1). Twinning is explained by describing a simplified Pmcn archetype structure as polytype built of two kinds of rods, which contact via electron-pair micelles.