Twinning by pseudomerohedry
From Online Dictionary of Crystallography
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 symmetry elements for the lattice; these elements can act as twin elements (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