The ferroelasticity effect of the incommensurate phase of quartz is discuss
ed. It is pointed out that the effect discussed in the paper by Saint-Grego
ire et al (Saint-Gregoire P, Snoeck E, Roucau C, Luk'yanchuk 1 and Janovec
V 1996 JETP Lett. 64 410) is negligibly small, and cannot explain the anoma
lous observations near the alpha <-> beta transition in quartz.