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 = 0.60 GPa _database_code_amcsd 0001971 9.4890 18.1508 5.3102 90 102.210 90 C2/m atom x y z occ Biso Fe1 0 .0871 .5 .405 .69 Mg1 0 .0871 .5 .595 .69 Fe2 0 .1776 0 .207 .71 Mg2 0 .1776 0 .789 .71 Al2 0 .1776 0 .004 .71 Fe3 0 0 0 .393 .70 Mg3 0 0 0 .607 .70 Fe4 0 .2590 .5 .927 .92 Mg4 0 .2590 .5 .035 .92 Ca4 0 .2590 .5 .038 .92 Si1 .2883 .0840 .2757 .60 Si2 .2978 .1686 .7818 .63 O1 .1160 .0871 .2096 .79 O2 .1266 .1724 .7202 .69 O3 .1166 0 .7093 .80 O4 .3807 .2451 .7675 1.07 O5 .3527 .1309 .0640 .85 O6 .3524 .1184 .5607 1.24 O7 .3432 0 .2694 1.02