data_global _chemical_name_mineral 'Melilite' loop_ _publ_author_name 'Bindi L' 'Bonazzi P' _journal_name_full 'Physics and Chemistry of Minerals' _journal_volume 32 _journal_year 2005 _journal_page_first 89 _journal_page_last 96 _publ_section_title ; Incommensurate-normal phase transition in natural melilite: an in situ high-temperature X-ray single-crystal study Sample: San Venanzo, Italy; T = 573 K Note: xO1 and yO1 corrected by authors ; _database_code_amcsd 0008960 _chemical_formula_sum 'Ca1.87 Na.1 Sr.02 K.02 Mg.96 Al.09 Si1.98 O7' _cell_length_a 7.857 _cell_length_b 7.857 _cell_length_c 5.022 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 310.020 _exptl_crystal_density_diffrn 2.926 _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 CaX 0.33210 0.16790 0.50570 0.93500 0.03140 NaX 0.33210 0.16790 0.50570 0.05000 0.03140 SrX 0.33210 0.16790 0.50570 0.01000 0.03140 KX 0.33210 0.16790 0.50570 0.01000 0.03140 MgT1 0.00000 0.00000 0.00000 0.96000 0.02070 AlT1 0.00000 0.00000 0.00000 0.07000 0.02070 SiT2 0.13950 0.36050 0.93470 0.99000 0.01810 AlT2 0.13950 0.36050 0.93470 0.01000 0.01810 O1 0.50000 0.00000 0.17990 1.00000 0.03430 O2 0.14060 0.35940 0.25310 1.00000 0.03760 O3 0.08120 0.18770 0.78670 1.00000 0.03340