Fluorapatite Hughes J M, Cameron M, Mariano A N American Mineralogist 76 (1991) 1165-1173 Rare-earth-element ordering and structural variations in natural rare-earth-bearing apatites sample from the Oka carbonatite _database_code_amcsd 0001374 9.3995 9.3995 6.8941 90 90 120 P6_3/m atom x y z occ Biso Ca1 2/3 1/3 .0011 .980 .893 Na1 2/3 1/3 .0011 .005 .893 Ce1 2/3 1/3 .0011 .015 .893 Ca2 .99212 .24276 .25 .955 .842 Ce2 .99212 .24276 .25 .045 .842 P .36875 .39813 .25 .947 .57 Si .36875 .39813 .25 .053 .57 O1 .4849 .3269 .25 .96 O2 .4659 .5873 .25 1.08 O3 .2573 .3421 .0705 1.32 F 0 0 .25 .74 2.7 OH 0 0 .302 .13 1.3