Word to the Wise: Phase Transition
Rocks & Minerals (81:06)
Page 467. John Rakovan
This animation depicts the evolution of the crystal structure of quartz as a function of temperature, through the alpa-beta quartz transition. As temperature increases the silica tetrahedra rotate about their shared oxygen atoms (depicted by the corners of the tetrahedra). It is based upon the data of Kihara (1990) from room temperature to 805°C. Take note, especially, of the transformation from the trigonal alpha-quartz to the hexagonal beta-quartz. This displacive transformation occurs at approximately 573°C. Animation created by Greg Schmidt using the program Xtaldraw, courtesy of Bob Downs, University of Arizona.
REFERENCE: Kihara, K. 1990. An X-ray study of the temperature dependence of the quartz structure European Journal of Mineralogy 2:63-77.