Cummingtonite Yang H, Hazen R M, Prewitt C T, Finger L W, Lu R, Hemley R J American Mineralogist 83 (1998) 288-299 High-pressure single-crystal X-ray diffraction and infrared spectroscopic studies of the C2/m-P2_1/m phase transition in cummingtonite Sample: P = 0.00 GPa, in air _database_code_amcsd 0001970 9.5220 18.1833 5.3184 90 102.020 90 C2/m atom x y z occ Biso Fe1 0 .0874 .5 .405 .75 Mg1 0 .0874 .5 .595 .75 Fe2 0 .1776 0 .207 .78 Mg2 0 .1776 0 .789 .78 Al2 0 .1776 0 .004 .78 Fe3 0 0 0 .393 .61 Mg3 0 0 0 .607 .61 Fe4 0 .2592 .5 .927 .93 Mg4 0 .2592 .5 .035 .93 Ca4 0 .2592 .5 .038 .93 Si1 .2865 .0841 .2735 .67 Si2 .2972 .1685 .7800 .60 O1 .1139 .0875 .2070 .76 O2 .1243 .1729 .7181 .90 O3 .1181 0 .7081 .87 O4 .3808 .2450 .7682 .95 O5 .3518 .1302 .0622 .86 O6 .3504 .1190 .5558 1.17 O7 .3433 0 .2723 .94