what is twinning
Twinning (crystallography). A process in which two or more crystals, or parts of crystals, assume orientations such that one may be brought to coincidence with the other by reflection across a plane or by rotation about an axis.winning of calcite by the pressure of a blade (Baumhauerâs method). If the structural homogeneity of a single crystal is disrupted by a great number of twin formations, the crystal is called a polysynthetic twin (Figure 3).