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 = 4.2 K _database_code_amcsd 0001807 5.6740 15.1049 6.4909 90 118.513 90 *I2/a .25 .25 .25 atom x y z Biso Ca .5 .07996 .25 .098 S 0 .07667 .75 .104 O1 .96413 .13282 .55028 .297 O2 .75763 .02194 .66427 .280 Ow .38342 .17240 .46179 .318 D1 .25369 .16662 .50769 1.428 D2 .40549 .24481 .49322 1.288