data_global
_chemical_name_mineral 'Gehlenite'
loop_
_publ_author_name
'Louisnathan S J'
_journal_name_full 'The Canadian Mineralogist'
_journal_volume 10 
_journal_year 1971
_journal_page_first 822
_journal_page_last 837
_publ_section_title
;
 Refinement of the crystal structure of a natural gehlenite, Ca2Al(Al,Si)2O7
;
_database_code_amcsd 0005090
_chemical_compound_source 'Crestmore, California, USA'
_chemical_formula_sum 'Ca2 Al1.91 Mg.05 Fe.02 Si1.02 O7'
_cell_length_a 7.716
_cell_length_b 7.716
_cell_length_c 5.089
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 302.982
_exptl_crystal_density_diffrn      3.011
_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   0.33750   0.16250   0.51100   1.00000
AlT1   0.00000   0.00000   0.00000   0.93000
MgT1   0.00000   0.00000   0.00000   0.05000
FeT1   0.00000   0.00000   0.00000   0.02000
AlT   0.14310   0.35690   0.95280   0.49000
SiT   0.14310   0.35690   0.95280   0.51000
O1   0.50000   0.00000   0.18840   1.00000
O2   0.14180   0.35820   0.28320   1.00000
O3   0.08720   0.17060   0.80330   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 0.01719 0.01719 0.03188 0.00452 -0.00259 0.00259
AlT1 0.00845 0.00845 0.02204 0.00000 0.00000 0.00000
MgT1 0.00845 0.00845 0.02204 0.00000 0.00000 0.00000
FeT1 0.00845 0.00845 0.02204 0.00000 0.00000 0.00000
AlT 0.00814 0.00814 0.01797 0.00181 -0.00159 0.00159
SiT 0.00814 0.00814 0.01797 0.00181 -0.00159 0.00159
O1 0.02986 0.02986 0.01732 0.00694 0.00000 0.00000
O2 0.01840 0.01840 0.02768 -0.00271 -0.00099 0.00099
O3 0.02262 0.01689 0.02821 0.00633 -0.00139 -0.00477