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 = 298 K
 Note: xO1 and yO1 corrected by authors
;
_database_code_amcsd 0008953
_chemical_formula_sum 'Ca1.87 Na.1 Sr.02 K.02 Mg.96 Al.09 Si1.98 O7'
_cell_length_a 7.826
_cell_length_b 7.826
_cell_length_c 5.004
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 306.476
_exptl_crystal_density_diffrn      2.960
_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   0.33160   0.16840   0.50650   0.93500   0.03540
NaX   0.33160   0.16840   0.50650   0.05000   0.03540
SrX   0.33160   0.16840   0.50650   0.01000   0.03540
KX   0.33160   0.16840   0.50650   0.01000   0.03540
MgT1   0.00000   0.00000   0.00000   0.96000   0.02670
AlT1   0.00000   0.00000   0.00000   0.07000   0.02670
SiT2   0.13990   0.36010   0.93590   0.99000   0.02590
AlT2   0.13990   0.36010   0.93590   0.01000   0.02590
O1   0.50000   0.00000   0.18050   1.00000   0.04010
O2   0.14080   0.35920   0.25580   1.00000   0.03670
O3   0.07950   0.18680   0.78640   1.00000   0.03970