SiO2 Boisen M B, Gibbs G V, Bukowinski M S T Physics and Chemistry of Minerals 21 (1994) 269-284 Framework silica structures generated using simulated annealing with a potential energy function based on an H6Si2O7 molecule Sample: 8 _database_code_amcsd 0007873 8.8664 4.7482 8.7918 90 115.4133 90 C2/c atom x y z Si .81229 .12825 .18687 O1 .25 .25 .5 O2 .18810 .62173 .68770 O3 0 .00488 .25