AM_Tridymite_4 Formula: Si O2 Name: Tridymite Unit cell: 26.1753 4.98437 8.2006 90.0 90.0 90.0 , V=1069.91 Space group: P212121 (19)

Graetsch H , Physics and Chemistry of Minerals , 28 (2001) p.313-321, X-ray powder diffraction study on the modulated high temperature forms, of SiO2 tridymite between 110 and 220 C, Sample: superstructure, T = 115 C, Locality: synthetic