Twinning by pseudomerohedry

Maclage par pseudomériédrie (Fr). Pseudomeroedrische Verzwillingung (Ge). Geminazione per pseudomeroedria (It). 擬欠面双晶 (Ja). Macla por seudomeroedría (Sp).

A lattice is said to be pseudosymmetric if at least a lattice row or/and a lattice plane approximately correspond to elements of symmetry; these elements can act as twinning operators (e.g. a monoclinic lattice with its oblique angle close to 90° is pseudo-orthorhombic and thus shows two pseudo twofold axes and two pseudo mirror planes).

See also

• Chapter 3.3 of International Tables for Crystallography, Volume D