• twinning;
  • crystal morphology;
  • dendrites;
  • electron backscatter diffraction (EBSD);
  • lithium silicate;
  • solid solutions;
  • β-eucryptite;
  • β-quartz

Snowflake-shaped dendrites of β-eucryptite–β-quartz solid solution were artificially crystallized in a matt glaze, and the crystallographic orientation of the dendrites was analysed by the electron backscatter diffraction (EBSD) technique. The six branches of a snowflake-shaped dendrite in the plane (0001) are along 〈110〉. From the orientation determination, a twin relationship and a topotactic relationship between dendrites were found. The twin axes are [011], [inline image] and [210], and the twin planes perpendicular to the twin axes are (inline image) and (inline image). From the reticular theory of twinning, it was calculated that the twin index n = 2 and the obliquity ω = 3.2877°. The studied dendrite is a twin by reticular pseudomerohedry with low twin index and obliquity. In the topotactic growth, no twin elements have been found, but the three main crystallographic directions 〈001〉, 〈210〉 and 〈110〉 of the two dendritic crystals overlap each other. The degree of lattice coincidence between the two crystals in this topotactic growth is also discussed.