data_global
_chemical_name_mineral 'Gehlenite'
loop_
_publ_author_name
'Swainson I P'
'Dove M T'
'Schmahl W W'
'Putnis A'
_journal_name_full 'Physics and Chemistry of Minerals'
_journal_volume 19 
_journal_year 1992
_journal_page_first 185
_journal_page_last 195
_publ_section_title
;
 Neutron powder diffraction study of the akermanite-gehlenite
 solid solution series
 Sample: 25% Ak
;
_database_code_amcsd 0007695
_chemical_formula_sum 'Ca2 Mg.21 Al1.54 Si1.24 O7'
_cell_length_a 7.7115
_cell_length_b 7.7115
_cell_length_c 5.0498
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 300.298
_exptl_crystal_density_diffrn      3.026
_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
Ca   0.33770   0.16230   0.51000   1.00000
MgT1   0.00000   0.00000   0.00000   0.21000
AlT1   0.00000   0.00000   0.00000   0.79000
AlT2   0.14210   0.35790   0.95030   0.37500
SiT2   0.14210   0.35790   0.95030   0.62000
O1   0.50000   0.00000   0.17930   1.00000
O2   0.14300   0.35700   0.27560   1.00000
O3   0.08610   0.17170   0.80300   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
Ca 0.02443 0.00244 0.00899 0.01190 0.00000 0.00000
MgT1 0.01088 0.00108 0.00810 0.00000 0.00000 0.00000
AlT1 0.01088 0.00108 0.00810 0.00000 0.00000 0.00000
AlT2 0.00467 0.00045 0.00417 -0.00087 0.00164 0.00164
SiT2 0.00467 0.00045 0.00417 -0.00087 0.00164 0.00164
O1 0.01747 0.00169 0.00620 -0.01214 0.00000 0.00000
O2 0.01720 0.00172 0.01000 0.00000 0.00456 0.00456
O3 0.02151 0.00108 0.01190 -0.00443 0.00353 -0.00304