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

Owyheeite [Cu0.09   (1)Ag2.77   (4)Pb10.23   (4)Sb10.89   (5)S28.00   (5)] crystallizes as a twofold superstructure with P21/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.

Source: Acta Crystallographica Section B - June 23, 2023 Category: Chemistry Authors: St ö ger, B. G ö b, C. Topa, D. Tags: mineral superstructure polytypism twinning research papers Source Type: research