Gypsum Schofield P F, Knight K S, Stretton I C American Mineralogist 81 (1996) 847-851 Thermal expansion of gypsum investigated by neutron powder diffraction T = 150 K _database_code_amcsd 0001808 5.6742 15.1236 6.5018 90 118.495 90 *I2/a .25 .25 .25 atom x y z Biso Ca .5 .07984 .25 .207 S 0 .07695 .75 .237 O1 .96371 .13292 .55070 .602 O2 .75753 .02170 .66443 .518 Ow .38222 .18229 .46024 .795 D1 .25341 .16210 .50655 1.911 D2 .40493 .24446 .49252 1.728