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 = 463 K
 Note: xO1 and yO1 corrected by authors
;
_database_code_amcsd 0008958
_chemical_formula_sum 'Ca1.87 Na.1 Sr.02 K.02 Mg.96 Al.09 Si1.98 O7'
_cell_length_a 7.845
_cell_length_b 7.845
_cell_length_c 5.011
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 308.397
_exptl_crystal_density_diffrn      2.941
_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   0.50580   0.93500   0.03800
NaX   0.33210   0.16790   0.50580   0.05000   0.03800
SrX   0.33210   0.16790   0.50580   0.01000   0.03800
KX   0.33210   0.16790   0.50580   0.01000   0.03800
MgT1   0.00000   0.00000   0.00000   0.96000   0.02900
AlT1   0.00000   0.00000   0.00000   0.07000   0.02900
SiT2   0.13970   0.36030   0.93500   0.99000   0.02760
AlT2   0.13970   0.36030   0.93500   0.01000   0.02760
O1   0.50000   0.00000   0.17870   1.00000   0.03810
O2   0.14050   0.35950   0.25500   1.00000   0.04220
O3   0.08110   0.18730   0.78630   1.00000   0.04040