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 after Levien and Prewitt (1981)
 with O3-O3-O3 angle = 166.4 and model oxygen radius = 1.319
;
_database_code_amcsd 0003480
_chemical_formula_sum 'Mg Ca Si2 O6'
_cell_length_a 9.760
_cell_length_b 9.071
_cell_length_c 5.237
_cell_angle_alpha 90
_cell_angle_beta 108.7
_cell_angle_gamma 90
_cell_volume 439.171
_exptl_crystal_density_diffrn      3.275
_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   0.30820   0.08333   0.26760
O1   0.13350   0.08333   0.16310
O2   0.36640   0.25000   0.33690
O3   0.36640   0.01720   0.03510