data_global
_chemical_name_mineral 'Pigeonite'
loop_
_publ_author_name
'Nestola F'
'Tribaudino M'
'Ballaran T B'
_journal_name_full 'American Mineralogist'
_journal_volume 89 
_journal_year 2004
_journal_page_first 189
_journal_page_last 196
_publ_section_title
;
 High pressure behavior, transformation and crystal structure of synthetic iron-free pigeonite
 Sample: P = 0 GPa
;
_database_code_amcsd 0003197
_chemical_formula_sum 'Mg1.85 Ca.15 Si2 O6'
_cell_length_a 9.646
_cell_length_b 8.842
_cell_length_c 5.201
_cell_angle_alpha 90
_cell_angle_beta 108.35
_cell_angle_gamma 90
_cell_volume 421.037
_exptl_crystal_density_diffrn      3.205
_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
MgM2   0.25530   0.01740   0.22230   0.85000   0.02153
CaM2   0.25530   0.01740   0.22230   0.15000   0.02153
MgM1   0.25090   0.65380   0.22170   1.00000   0.00899
SiTA   0.04240   0.34090   0.28730   1.00000   0.00785
SiTB   0.55050   0.83780   0.23290   1.00000   0.00823
O1A   0.86710   0.33940   0.17800   1.00000   0.00988
O2A   0.12070   0.50160   0.32400   1.00000   0.01001
O3A   0.10670   0.27380   0.60000   1.00000   0.01013
O1B   0.37390   0.83980   0.12800   1.00000   0.01001
O2B   0.63070   0.98520   0.38100   1.00000   0.01596
O3B   0.60470   0.70090   0.46700   1.00000   0.01305
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
MgM2 0.02100 0.01960 0.01740 0.00430 -0.00590 0.00420
CaM2 0.02100 0.01960 0.01740 0.00430 -0.00590 0.00420