Tridymite Graetsch H, Topalovic-Dierdorf I European Journal of Mineralogy 8 (1996) 103-113 29Si MAS NMR spectrum and superstructure of modulated tridymite L3-To(MX-1) Sample: average crystal structure Locality: synthetic _database_code_amcsd 0006616 5.007 8.6004 8.2169 90 91.512 90 Cc atom x y z Uiso U(1,1) U(2,2) U(3,3) U(1,2) U(1,3) U(2,3) Si1 .0764 .3073 .2108 .052 .043 .033 .080 .004 .031 .006 Si2 .0773 .3592 .8352 .052 .042 .034 .082 .004 .031 .008 O1 .2885 .7530 .2534 .044 .039 .047 .046 .010 .001 -.003 O2 .1440 .4647 .3082 .085 .048 .030 .176 -.014 -.017 .009 O3 .2884 .1797 .2703 .138 .032 .032 .350 .008 -.002 .008 O4 .5826 .1668 .5198 .188 .266 .216 .090 -.023 .132 -.014