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 43167 Locality: Moctezuma, Sonora, Mexico _database_code_amcsd 0018789 15.960 15.960 7.238 90 90 120 R3m atom x y z occ Uiso NaX 0 0 .2366 .77 .0241 CaX 0 0 .2366 .18 .0241 MgY .12392 .06196 .6346 .4667 .0071 AlY .12392 .06196 .6346 .14 .0071 Fe2Y .12392 .06196 .6346 .07 .0071 Fe3Y .12392 .06196 .6346 .3233 .0071 AlZ .29810 .26164 .6122 .8417 .0062 FeZ .29810 .26164 .6122 .0817 .0062 MgZ .29810 .26164 .6122 .0767 .0062 SiT .19154 .18981 0 .9633 .0060 BT .19154 .18981 0 .0283 .0060 TiT .19154 .18981 0 .0083 .0060 B .1099 .2198 .4549 .0090 OH1 0 0 .773 .600 .0178 O1 0 0 .773 .400 .0178 O2 .0613 .1226 .4861 .0128 O3 .2636 .1318 .5126 .0137 O4 .0930 .1860 .0696 .0121 O5 .1840 .0920 .0904 .0110 O6 .1957 .1858 .7783 .0100 O7 .2846 .2846 .0791 .0103 O8 .2092 .2695 .4416 .0117 H3 .254 .127 .401 .0150