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

© International Union of Crystallography 2006
International Tables for Crystallography (2006). Vol. D. ch. 3.3, p. 409

Figure 3.3.6.9 

Th. Hahna* and H. Klapperb

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 3.3.6.9]
Figure 3.3.6.9

Various forms of rutile (TiO2) twins, with one or several equivalent twin reflection planes {011}. (a) Elbow twin (two orientation states). (b) Twin with two orientation states. One component has the form of an inserted lamella. (c) Triple twin (three orientation states) with twin reflection planes (011) and [(0{\bar 1}1)]. (d) Triple twin with twin reflection planes (011) and (101). (e) Cyclic sixfold twin with six orientation states. Two sectors appear strongly distorted due to the large angular excess of 35.6°. (f) Cyclic eightfold twin with eight orientation states. (g) Perspective view of the cyclic twin of (e). (h) Photograph of a rutile eightling (ca. 15 mm diameter) from Magnet Cove, Arkansas (Geologisk Museum, Kopenhagen). Parts (a) to (e) courtesy of H. Strunz, Unterwössen, cf. Ramdohr & Strunz, 1967[link], p. 512. Photograph (h) courtesy of M. Medenbach, Bochum.