data_9003382
_publ_section_title
;Model pyroxenes II: Structural variation as a function of tetrahedral
 rotation model with O3-O3-O3 angle = 240 and model oxygen radius = 1 Note:
 Atoms Mg, Si, and O are assigned to atomic positions for convenience
;
_journal_name_full               'American Mineralogist'
_journal_page_first              614
_journal_page_last               628
_journal_volume                  89
_journal_year                    2004
_chemical_formula_sum            'Mg O3 Si'
_chemical_name_mineral           Pyroxene-ideal
_space_group_IT_number           15
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/c 1'
_cell_angle_alpha                90
_cell_angle_beta                 117.9
_cell_angle_gamma                90
_cell_length_a                   7.394
_cell_length_b                   6
_cell_length_c                   3.464
_cell_volume                     135.814
_exptl_crystal_density_diffrn    9.819
_[local]_cod_chemical_formula_sum_orig 'Mg Si O3'
_cod_database_code               9003382
loop_
_symmetry_equiv_pos_as_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
Mg1 0.00000 0.91667 0.25000
Mg2 0.00000 0.25000 0.25000
Si 0.31250 0.08333 0.39583
O1 0.12500 0.08333 0.20833
O2 0.37500 0.25000 0.29167
O3 0.37500 0.91667 0.29167
