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

International Tables for Crystallography (2006). Vol. D. ch. 1.6, p. 155

Figure 1.6.4.1 

A. M. Glazera* and K. G. Coxb

a Department of Physics, University of Oxford, Parks Roads, Oxford OX1 3PU, England, and bDepartment of Earth Sciences, University of Oxford, Parks Roads, Oxford OX1 3PR, England
Correspondence e-mail:  glazer@physics.ox.ac.uk

[Figure 1.6.4.1]
Figure 1.6.4.1

A thin section of a rock containing the minerals aegirine (elongated crystals) and eudyalite (the matrix) viewed in plane-polarized light in two positions at right angles to each other [(a) and (b)]. Aegirine shows pleochroism from grass-green to yellow–green (compare specific crystals in the two photographs). Eudyalite shows pleochroism from pink to almost colourless.