data_global
_chemical_name_mineral 'Pyroxene-ideal'
loop_
_publ_author_name
'Thompson R M'
'Downs R T'
_journal_name_full 'American Mineralogist'
_journal_volume 89 
_journal_year 2004
_journal_page_first 614
_journal_page_last 628
_publ_section_title
;
 Model pyroxenes II: Structural variation as a function of tetrahedral rotation
 model diopside at 5.3 GPa after Levien and Prewitt (1981)
 with O3-O3-O3 angle = 163.6 and model oxygen radius = 1.304
;
_database_code_amcsd 0003481
_chemical_formula_sum 'Mg Ca Si2 O6'
_cell_length_a 9.607
_cell_length_b 8.939
_cell_length_c 5.161
_cell_angle_alpha 90
_cell_angle_beta 108.3
_cell_angle_gamma 90
_cell_volume 420.796
_exptl_crystal_density_diffrn      3.418
_symmetry_space_group_name_H-M 'C 1 2/c 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2+y,z'
  'x,-y,1/2+z'
  '1/2+x,1/2-y,1/2+z'
  '-x,y,1/2-z'
  '1/2-x,1/2+y,1/2-z'
  '-x,-y,-z'
  '1/2-x,1/2-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
Mg   0.00000   0.91667   0.25000
Ca   0.00000   0.25000   0.25000
Si   0.30830   0.08333   0.26320
O1   0.13330   0.08333   0.16110
O2   0.36670   0.25000   0.33890
O3   0.36670   0.02080   0.02640