data_global _chemical_name_mineral 'Phase-X' loop_ _publ_author_name 'Mancini F' 'Harlow G E' 'Cahill C L' _journal_name_full 'American Mineralogist' _journal_volume 87 _journal_year 2002 _journal_page_first 302 _journal_page_last 306 _publ_section_title ; The crystal structure and cation ordering of phase-X - (K1-x-n)2(Mg1-n[Al,Cr]n)2Si2O7H2x: A potential K- and H-bearing phase in the mantle ; _database_code_amcsd 0002757 _chemical_formula_sum 'Si2 Mg1.84 Al.06 Cr.02 K6 O7' _cell_length_a 5.028 _cell_length_b 5.028 _cell_length_c 13.216 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 289.348 _exptl_crystal_density_diffrn 5.167 _symmetry_space_group_name_H-M 'P 63 c m' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,z' 'x-y,x,1/2+z' '-y,-x,1/2+z' '-y,x-y,z' 'x-y,-y,z' '-x,-y,1/2+z' 'x,x-y,1/2+z' '-x+y,-x,z' 'y,x,z' 'y,-x+y,1/2+z' '-x+y,y,1/2+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy Si1 0.00000 0.00000 0.01270 1.00000 Si2 0.00000 0.00000 0.26020 1.00000 MgM -0.33333 0.33333 0.13770 0.92000 AlM -0.33333 0.33333 0.13770 0.03000 CrM -0.33333 0.33333 0.13770 0.01000 K 0.35320 0.64530 0.38750 1.00000 O1 0.31240 0.00000 0.22840 1.00000 O2 0.00000 0.00000 -0.11100 1.00000 O3 -0.31060 0.00000 0.04930 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 Si1 0.01020 0.01020 0.00650 0.00510 0.00000 0.00000 Si2 0.00690 0.00690 0.00010 0.00345 0.00000 0.00000 MgM 0.00800 0.00800 0.01370 0.00400 0.00000 0.00000 AlM 0.00800 0.00800 0.01370 0.00400 0.00000 0.00000 CrM 0.00800 0.00800 0.01370 0.00400 0.00000 0.00000 K 0.01530 0.02390 0.00820 -0.00300 0.00260 -0.00010 O1 0.00510 0.00350 0.00520 0.00175 0.00050 0.00000 O2 0.02010 0.02010 0.00840 0.01005 0.00000 0.00000 O3 0.01530 0.02010 0.01900 0.01005 -0.00040 0.00000