Hydroxylapatite Wilson R M, Elliot J C, Dowker S E P American Mineralogist 84 (1999) 1406-1414 Rietveld refinement of the crystallographic structure of human dental enamel apatites Sample: H6M, synthetic _database_code_amcsd 0002283 9.4172 9.4172 6.8799 90 90 120 P6_3/m atom x y z occ Ca1 2/3 1/3 .0017 Ca2 .2467 .9933 .25 P .3979 .3678 .25 O1 .3275 .4844 .25 O2 .5860 .4649 .25 O3 .3424 .2577 .0685 OH 0 0 .1999 .5 H 0 0 .0608 .5