data_global
_chemical_name_mineral 'Pigeonite'
loop_
_publ_author_name
'Clark J R'
'Ross M'
'Appleman D E'
_journal_name_full 'American Mineralogist'
_journal_volume 56 
_journal_year 1971
_journal_page_first 888
_journal_page_last 908
_publ_section_title
;
 Crystal chemistry of a lunar pigeonite
 class b data refinement
;
_database_code_amcsd 0000248
_chemical_formula_sum '(Mg.54 Fe.46) Si O3'
_cell_length_a 9.678
_cell_length_b 8.905
_cell_length_c 5.227
_cell_angle_alpha 90
_cell_angle_beta 108.71
_cell_angle_gamma 90
_cell_volume 426.671
_exptl_crystal_density_diffrn      3.577
_symmetry_space_group_name_H-M 'P 1 21/c 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'x,1/2-y,1/2+z'
  '-x,1/2+y,1/2-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
Mg1   0.25060   0.65480   0.23000   0.67000   0.00697
Fe1   0.25060   0.65480   0.23000   0.33000   0.00697
Mg2   0.25640   0.01670   0.22460   0.41000   0.00646
Fe2   0.25640   0.01670   0.22460   0.59000   0.00646
SiA   0.04340   0.33990   0.28440   1.00000   0.00507
SiB   0.55200   0.83640   0.23680   1.00000   0.00431
O1A   0.86840   0.33730   0.17400   1.00000   0.00722
O1B   0.37550   0.83570   0.12960   1.00000   0.00545
O2A   0.12310   0.49770   0.33120   1.00000   0.00988
O2B   0.63140   0.98500   0.38140   1.00000   0.00747
O3A   0.10480   0.26830   0.59170   1.00000   0.01418
O3B   0.60450   0.70470   0.47070   1.00000   0.01330
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
Mg2 0.00724 0.00723 0.00472 0.00124 0.00138 0.00089
Fe2 0.00724 0.00723 0.00472 0.00124 0.00138 0.00089
O3A 0.00936 0.02169 0.01180 0.00000 0.00368 0.00737
O3B 0.00936 0.01768 0.01366 0.00289 0.00506 0.00581