Er2Si2O7 Smolin Y I, Shepelev Y F Acta Crystallographica B26 (1970) 484-492 The crystal structures of the rare earth pyrosilicates _database_code_amcsd 0009371 4.683 5.556 10.79 90 90 96 P2_1/b atom x y z Biso Er .88829 .09318 .34934 .29 Si .3601 .6442 .3871 .33 O1 .5 .5 .5 .91 O2 .2052 .8653 .4486 .64 O3 .1235 .4583 .3191 .63 O4 .6184 .7522 .2984 .56