Calcite Markgraf S A, Reeder R J American Mineralogist 70 (1985) 590-600 High-temperature structure refinements of calcite and magnesite Sample: T = 750 C _database_code_amcsd 0000988 4.978 4.978 17.462 90 90 120 R-3c atom x y z B(1,1) B(2,2) B(3,3) B(1,2) B(1,3) B(2,3) Ca 0 0 0 .0464 .0464 .00306 .0232 0 0 C 0 0 .25 .042 .042 .0023 .021 0 0 O .2528 0 .25 .055 .110 .0060 .055 -.00495 -.0099