Nacrite Gruner J Zeitschrift fur Kristallographie 85 (1933) 345-354 The crystal structure of Nacrite and a comparison of certain optical properties of the caolin group with its structures _cod_database_code 1011080 _database_code_amcsd 0017977 5.16 8.93 28.659990000 90 91.72 90 Cc atom x y z Al1 -.25 .3333 0 Al2 -.25 0 0 Al3 .0833 0 .25 Al4 .0833 -.3333 .25 Si1 .4306 .3333 .0938 Si2 .4306 0 .094 Si3 .4306 -.3333 .3438 Si4 .4306 0 .3438 O1 -.0778 .5 .03819 O2 -.0778 -.1667 .03819 O3 .4361 .1667 .1146 O4 .1861 .4167 .1146 O5 .1861 -.0833 .1146 O6 -.0778 -.5 .2882 O7 -.0778 .1667 .2882 O8 .4361 -.1667 .3646 O9 .1861 -.4167 .3646 O10 .1861 .0833 .3646 O11 -.0778 .1667 .03819 O12 -.2556 -.3333 .2119 O13 -.2556 0 .2119 O14 -.2556 .3333 .2119 O15 -.0778 -.167 .2882 O16 .0778 -.3333 .4618 O17 .0778 0 .4618 O18 .0778 .3333 .4618