Cristobalite Le Bail A Journal of Non-Crystalline Solids 183 (1995) 39-42 Modelling the silica glass structure by the Rietveld method Note: model for amorphous silica based on cristobalite-type topology _database_code_amcsd 0020708 7.22 7.09 7.30 90 90 90 P2_12_12_1 atom x y z Si1 .277 .275 .282 Si2 .009 .022 .016 O1 .125 .149 .152 O2 .635 .657 .061 O3 .065 .646 .654 O4 .670 .060 .621