Phlogopite Hendricks S B, Jefferson M E American Mineralogist 24 (1939) 729-771 Polymorphism of the micas with optical measurements Note: data is reproduced from Jackson and West (1930) _database_code_amcsd 0000025 5.32 9.21 20.08 90 95 90 C2/c atom x y z occ K 0 .083 .25 Mg1 .25 .083 0 Mg2 .75 .25 0 Si1 -.033 -.250 .135 .75 Si2 -.033 .417 .135 .75 Al1 -.033 -.250 .135 .25 Al2 -.033 .417 .135 .25 O1 .228 .333 .164 O2 .228 -.167 .164 O3 .480 .083 .164 O4 -.062 -.167 .055 O5 -.062 .417 .055 OH -.062 .083 .058 .50 F -.062 .083 .058 .50