data_global
_chemical_name_mineral 'Chevkinite-(Nd)'
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
 Coordinates to O8 revised by Dr. Zhuming Yang, December 2001
;
_database_code_amcsd 433
_chemical_compound_source 'natural, but location not given'
_chemical_formula_sum 'Nd4 Si4 Mg1.999 Ti3.001 O22'
_cell_length_a 13.328
_cell_length_b 5.727
_cell_length_c 10.971
_cell_angle_alpha 90.0
_cell_angle_beta 100.91
_cell_angle_gamma 90.0
_cell_volume 822.275
_exptl_crystal_density_diffrn  4.982
_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
Nd1   0.35442  0.0226  0.23312  1.0  0.0095
Nd2   0.07127  -0.03662  0.24017  1.0  0.0094
Si1   0.2015  0.4972  0.2306  1.0  0.0069
Si2   0.3596  0.5019  0.047  1.0  0.0076
Mg   0.0  0.5  0.0  1.0  0.0078
Ti1   0.2434  0.2466  0.5  0.68  0.0082
Mg1   0.2434  0.2466  0.5  0.32  0.0082
Ti2a   0.0  0.5  0.5  0.807  0.0111
Mg2a   0.0  0.5  0.5  0.193  0.0111
Ti2b   0.5  0.5  0.5  0.834  0.0093
Mg2b   0.5  0.5  0.5  0.166  0.0093
O1   0.2393  -0.2098  0.3133  1.0  0.0075
O11   0.217  0.2527  0.313  1.0  0.0081
O2   -0.0247  -0.2527  0.3742  1.0  0.0085
O21   -0.0214  0.2448  0.3736  1.0  0.0093
O3   0.4131  -0.2493  0.0946  1.0  0.0093
O31   0.4437  0.2947  0.0931  1.0  0.0107
O4   0.1457  -0.0104  0.4757  1.0  0.0106
O5   0.1511  0.5044  0.5099  1.0  0.0105
O6   0.0866  0.5469  0.1686  1.0  0.0113
O7   0.2741  0.4477  0.1307  1.0  0.0151
O8   0.3132  0.4892  -0.0985  1.0  0.0074