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 435
_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 90.0
_cell_angle_beta 113.85
_cell_angle_gamma 90.0
_cell_volume 845.672
_exptl_crystal_density_diffrn  4.76
_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  0.0198  0.26687  1.0  0.0078
La2   0.04897  0.0265  0.7432  1.0  0.0087
Si1   0.4123  -0.0001  0.7322  1.0  0.0057
Si2   0.1624  0.0027  0.5489  1.0  0.0069
Mg   0.0  0.5  0.5  1.0  0.0047
Ti1   -0.0039  0.2385  0.0004  0.616  0.0105
Mg1   -0.0039  0.2385  0.0004  0.384  0.0105
Ti2   0.2749  0.0071  0.017  0.884  0.0068
Mg2   0.2749  0.0071  0.017  0.116  0.0068
O1   0.0794  -0.2597  0.1864  1.0  0.0091
O11   0.0652  0.2556  0.1858  1.0  0.0103
O2   0.2899  0.2606  0.1229  1.0  0.0128
O21   0.2875  -0.2401  0.1225  1.0  0.0105
O3   0.3736  -0.2511  0.4058  1.0  0.0123
O31   0.392  0.2862  0.4066  1.0  0.0139
O4   0.0957  0.0077  0.9894  1.0  0.0114
O5   0.4067  -0.0041  0.0089  1.0  0.011
O6   0.4932  0.0328  0.666667  1.0  0.015
O7   0.2884  -0.0337  0.6366  1.0  0.0176
O8   0.1384  -0.0036  0.4042  1.0  0.0115