Quartz: Preferred Orientation in Rocks Produced by Dauphiné Twinning

Science  12 Jun 1970:
Vol. 168, Issue 3937, pp. 1342-1344
DOI: 10.1126/science.168.3937.1342


X-ray analyses of quartz aggregates deformed in the laboratory andin nature show a striking difference in the preferred orientation of the positive and negative trigonal forms. These observations may be accounted for by mechanically induced Dauphiné twinning. This orienting mechanism is unusual in that it requires no permanent strain.