data_global _chemical_name_mineral 'Dravite' loop_ _publ_author_name 'Schmetzer K' 'Nuber B' 'Abraham K' _journal_name_full 'Neues Jahrbuch fur Mineralogie, Abhandlungen' _journal_volume 136 _journal_year 1979 _journal_page_first 93 _journal_page_last 112 _publ_section_title ; Zur Kristallchemie Magnesium-reicher Turmaline ; _database_code_amcsd 0019011 _chemical_compound_source 'Gerevi Hills, Tanzania' _chemical_formula_sum 'Na.6 Ca.29 K.02 Mg2.37 Al6.63 Si6 B3 O31 H3.75' _cell_length_a 15.923 _cell_length_b 15.923 _cell_length_c 7.201 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 1581.151 _exptl_crystal_density_diffrn 3.035 _symmetry_space_group_name_H-M 'R 3 m' loop_ _space_group_symop_operation_xyz 'x,y,z' '2/3+x,1/3+y,1/3+z' '1/3+x,2/3+y,2/3+z' 'x,x-y,z' '2/3+x,1/3+x-y,1/3+z' '1/3+x,2/3+x-y,2/3+z' '-y,-x,z' '2/3-y,1/3-x,1/3+z' '1/3-y,2/3-x,2/3+z' '-x+y,y,z' '2/3-x+y,1/3+y,1/3+z' '1/3-x+y,2/3+y,2/3+z' '-y,x-y,z' '2/3-y,1/3+x-y,1/3+z' '1/3-y,2/3+x-y,2/3+z' '-x+y,-x,z' '2/3-x+y,1/3-x,1/3+z' '1/3-x+y,2/3-x,2/3+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy Na 0.00000 0.00000 0.85760 0.60000 Ca 0.00000 0.00000 0.85760 0.29000 K 0.00000 0.00000 0.85760 0.02000 Mg 0.06250 -0.06250 0.45810 0.79000 Al 0.06250 -0.06250 0.45810 0.21000 Al 0.26170 0.29780 0.47900 1.00000 Si 0.18990 0.19190 0.09070 1.00000 B -0.10960 0.10960 0.63490 1.00000 O1 0.00000 0.00000 0.31750 0.25000 O-H1 0.00000 0.00000 0.31750 0.75000 O2 -0.06070 0.06070 0.60510 1.00000 O-H3 0.13260 -0.13260 0.57740 1.00000 O4 -0.09330 0.09330 0.02040 1.00000 O5 0.09160 -0.09160 -0.00110 1.00000 O6 0.18590 0.19590 0.31140 1.00000 O7 0.28460 0.28510 0.01110 1.00000 O8 0.26990 0.10930 0.64850 1.00000 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Na 0.01940 0.01940 0.02300 0.00970 0.00000 0.00000 Ca 0.01940 0.01940 0.02300 0.00970 0.00000 0.00000 K 0.01940 0.01940 0.02300 0.00970 0.00000 0.00000 Mg 0.00300 0.00300 0.01310 0.00040 0.00210 -0.00210 Al 0.00300 0.00300 0.01310 0.00040 0.00210 -0.00210 Al 0.00340 0.00300 0.00530 0.00160 -0.00010 0.00020 Si 0.00200 0.00190 0.00560 0.00100 0.00020 0.00020 B 0.00350 0.00350 0.00690 0.00210 0.00030 -0.00030 O1 0.00910 0.00910 0.00980 0.00460 0.00000 0.00000 O-H1 0.00910 0.00910 0.00980 0.00460 0.00000 0.00000 O2 0.00960 0.00960 0.01060 0.00740 0.00000 0.00000 O-H3 0.01040 0.01040 0.00640 -0.00040 -0.00040 0.00040 O4 0.00530 0.00530 0.01120 -0.00090 -0.00080 0.00080 O5 0.00480 0.00480 0.01160 -0.00220 -0.00050 0.00050 O6 0.00760 0.00740 0.01100 0.00430 0.00150 0.00150 O7 0.00390 0.00400 0.01040 0.00020 0.00100 0.00120 O8 0.00680 0.00260 0.01340 0.00200 -0.00220 -0.00040