Figure 3.3.7.3

Hahn, Th.; Klapper, H.

doi:10.1107/97809553602060000644

International
Tables for
Crystallography
Volume D
Physical properties of crystals
Edited by A. Authier

pdf | chapter contents | chapter index | related articles

International Tables for Crystallography (2006). Vol. D. ch. 3.3, p. 415

Figure 3.3.7.3

Th. Hahn^a ^* and H. Klapper^b

^a Institut für Kristallographie, Rheinisch–Westfälische Technische Hochschule, D-52056 Aachen, Germany, and ^bMineralogisch-Petrologisches Institut, Universität Bonn, D-53113 Bonn, Germany
Correspondence e-mail: hahn@xtal.rwth-aachen.de

Figure 3.3.7.3

Mechanical twins of calcite, CaCO₃. All indices refer to the standard morphological cell [cf. Section 3.3.10.2.2, Example (5)]. (a) Generation of a deformation twin by a knife-edge impact (after Baumhauer, 1879). (b) Description as a glide process (`twin glide') on plane ( $[01{\bar 1}2]$ ). (c), (d) Generation of deformation twins by compression of the cleavage rhombohedron $[\{10{\bar 1}1\}]$ (Mügge, 1883). The shaded twin components have the same orientation. (e) Successive stages of deformation twinning of NaNO₃ (isotypic with calcite) by uniaxial compression. The compression axis (vertical) is chosen with an angle of 45° against the twin glide plane $[(10{\bar 1}2)]$ and the glide direction $[[21{\bar 1}]]$ . The direction of the twofold axis is shown in the left-hand figure. Original size of the sample: ca. $[3\times 3\times\sim9.5]$ mm. Part (e) courtesy of H. E. Hoefer, PhD thesis, University of Cologne, 1989.