data_global
_chemical_name_mineral 'Perrierite-(La)'
loop_
_publ_author_name
'Calvo C'
'Faggiani R'
_journal_name_full 'American Mineralogist'
_journal_volume 59 
_journal_year 1974
_journal_page_first 1277
_journal_page_last 1285
_publ_section_title
;
 A re-investigation of the crystal structures of chevkinite and perrierite
;
_database_code_amcsd 0000435
_chemical_compound_source 'Synthetic'
_chemical_formula_sum 'La4 Si4 Mg2 Ti3 O22'
_cell_length_a 13.818
_cell_length_b 5.677
_cell_length_c 11.787
_cell_angle_alpha 90
_cell_angle_beta 113.85
_cell_angle_gamma 90
_cell_volume 845.672
_exptl_crystal_density_diffrn      4.760
_symmetry_space_group_name_H-M 'P 1 21/a 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2-y,z'
  '1/2-x,1/2+y,-z'
  '-x,-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
La1   0.23756   0.01980   0.26687   1.00000   0.00780
La2   0.04897   0.02650   0.74320   1.00000   0.00870
Si1   0.41230  -0.00010   0.73220   1.00000   0.00570
Si2   0.16240   0.00270   0.54890   1.00000   0.00690
Mg   0.00000   0.50000   0.50000   1.00000   0.00470
Ti1  -0.00390   0.23850   0.00040   0.61600   0.01050
Mg1  -0.00390   0.23850   0.00040   0.38400   0.01050
Ti2   0.27490   0.00710   0.01700   0.88400   0.00680
Mg2   0.27490   0.00710   0.01700   0.11600   0.00680
O1   0.07940  -0.25970   0.18640   1.00000   0.00910
O11   0.06520   0.25560   0.18580   1.00000   0.01030
O2   0.28990   0.26060   0.12290   1.00000   0.01280
O21   0.28750  -0.24010   0.12250   1.00000   0.01050
O3   0.37360  -0.25110   0.40580   1.00000   0.01230
O31   0.39200   0.28620   0.40660   1.00000   0.01390
O4   0.09570   0.00770   0.98940   1.00000   0.01140
O5   0.40670  -0.00410   0.00890   1.00000   0.01100
O6   0.49320   0.03280   0.66670   1.00000   0.01500
O7   0.28840  -0.03370   0.63660   1.00000   0.01760
O8   0.13840  -0.00360   0.40420   1.00000   0.01150