data_global _chemical_name_mineral 'Alumoakermanite' loop_ _publ_author_name 'Wiedenmann D' 'Zaitsev A N' 'Britvin S N' 'Krivovichev S V' 'Keller J' _journal_name_full 'Mineralogical Magazine' _journal_volume 73 _journal_year 2009 _journal_page_first 373 _journal_page_last 384 _publ_section_title ; Alumoakermanite, (Ca,Na)2(Al,Mg,Fe2+)(Si2O7), a new mineral from the active carbonatite-nephelinite-phonolite volcano Oldoinyo Lengai, northern Tanzania ; _database_code_amcsd 0020206 _chemical_compound_source 'Oldoinyo Lengai, northern Tanzania' _chemical_formula_sum '(Ca1.52 Na.48) (Al.5 Fe.3 Mg.2) Si2 O7' _cell_length_a 7.7661 _cell_length_b 7.7661 _cell_length_c 5.0297 _cell_angle_alpha 90. _cell_angle_beta 90. _cell_angle_gamma 90. _cell_volume 303.353 _exptl_crystal_density_diffrn 3.013 _symmetry_space_group_name_H-M 'P -4 21 m' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2-y,1/2-x,z' 'y,-x,-z' '1/2-x,1/2+y,-z' '-x,-y,z' '1/2+y,1/2+x,z' '-y,x,-z' '1/2+x,1/2-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Ca1 0.66382 0.83618 0.49132 0.76000 0.01820 Na1 0.66382 0.83618 0.49132 0.24000 0.01820 Al2 0.00000 0.00000 0.00000 0.50000 0.01250 Fe2 0.00000 0.00000 0.00000 0.30000 0.01250 Mg2 0.00000 0.00000 0.00000 0.20000 0.01250 Si 0.85952 0.64048 0.05699 1.00000 0.01169 O1 0.50000 0.00000 0.82400 1.00000 0.02370 O2 0.85812 0.64188 0.74110 1.00000 0.02460 O3 0.91720 0.81825 0.20260 1.00000 0.02570 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 Ca1 0.02040 0.02040 0.01380 0.00630 -0.00160 -0.00160 Na1 0.02040 0.02040 0.01380 0.00630 -0.00160 -0.00160 Al2 0.01110 0.01110 0.01540 0.00000 0.00000 0.00000 Fe2 0.01110 0.01110 0.01540 0.00000 0.00000 0.00000 Mg2 0.01110 0.01110 0.01540 0.00000 0.00000 0.00000 Si 0.01220 0.01220 0.01060 0.00140 0.00020 0.00020 O1 0.02930 0.02930 0.01200 -0.01700 0.00000 0.00000 O2 0.03010 0.03010 0.01360 0.00630 0.00250 0.00250 O3 0.03720 0.01860 0.02140 -0.00740 0.00530 -0.00450