Fluor-dravite Grice J D, Ercit T S Neues Jahrbuch fur Mineralogie, Abhandlungen 165 (1993) 245-266 Ordering of Fe and Mg in the tourmaline crystal structure: The correct formula Sample: Dravite 43873 Locality: Pierrepont, St, Lawrence Co., New York, USA _database_code_amcsd 0018791 15.999 15.999 7.236 90 90 120 R3m atom x y z occ Uiso NaX 0 0 .2298 .713 .0200 CaX 0 0 .2298 .301 .0200 MgY .12428 .06214 .6336 .74 .0076 Fe2Y .12428 .06214 .6336 .03 .0076 Fe3Y .12428 .06214 .6336 .23 .0076 AlZ .29811 .26179 .6125 .8817 .0052 Fe3Z .29811 .26179 .6125 .0367 .0052 MgZ .29811 .26179 .6125 .08 .0052 SiT .19173 .18998 0 .99 .0052 TiT .19173 .18998 0 .01 .0052 B .1098 .2196 .4538 .0069 F1 0 0 .7748 .42 .0138 OH1 0 0 .7748 .28 .0138 O1 0 0 .7748 .30 .0138 O2 .06092 .12184 .4798 .0103 O3 .26654 .13327 .5123 .0114 O4 .09252 .18504 .0706 .0096 O5 .1826 .09130 .0905 .0098 O6 .1961 .1867 .7783 .0088 O7 .2848 .2843 .0801 .0091 O8 .2094 .2699 .4418 .0101 H3 .262 .131 .409 .0100