The structure described by MgSiO3 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form MgO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(2) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. is represented by the CIF file [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.870
_cell_length_b   10.133
_cell_length_c   10.956
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   540.679
_cell_formula_units_Z   8
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Mg  Mg0  1  0.287  0.973  0.466  1.0
  Mg  Mg1  1  0.651  0.256  0.027  1.0
  Mg  Mg2  1  0.849  0.756  0.527  1.0
  Mg  Mg3  1  0.151  0.256  0.473  1.0
  Mg  Mg4  1  0.713  0.473  0.534  1.0
  Mg  Mg5  1  0.213  0.473  0.966  1.0
  Mg  Mg6  1  0.787  0.973  0.034  1.0
  Mg  Mg7  1  0.349  0.756  0.973  1.0
  Si  Si8  1  0.571  0.259  0.329  1.0
  Si  Si9  1  0.071  0.259  0.171  1.0
  Si  Si10  1  0.892  0.176  0.667  1.0
  Si  Si11  1  0.392  0.176  0.833  1.0
  Si  Si12  1  0.608  0.676  0.167  1.0
  Si  Si13  1  0.429  0.759  0.671  1.0
  Si  Si14  1  0.929  0.759  0.829  1.0
  Si  Si15  1  0.108  0.676  0.333  1.0
  O  O16  1  0.413  0.278  0.190  1.0
  O  O17  1  0.470  0.371  0.424  1.0
  O  O18  1  0.925  0.327  0.610  1.0
  O  O19  1  0.432  0.652  0.295  1.0
  O  O20  1  0.587  0.778  0.810  1.0
  O  O21  1  0.932  0.652  0.205  1.0
  O  O22  1  0.939  0.125  0.120  1.0
  O  O23  1  0.439  0.125  0.380  1.0
  O  O24  1  0.970  0.371  0.076  1.0
  O  O25  1  0.568  0.152  0.705  1.0
  O  O26  1  0.030  0.871  0.924  1.0
  O  O27  1  0.087  0.778  0.690  1.0
  O  O28  1  0.425  0.327  0.890  1.0
  O  O29  1  0.061  0.625  0.880  1.0
  O  O30  1  0.983  0.587  0.444  1.0
  O  O31  1  0.017  0.087  0.556  1.0
  O  O32  1  0.561  0.625  0.620  1.0
  O  O33  1  0.575  0.827  0.110  1.0
  O  O34  1  0.530  0.871  0.576  1.0
  O  O35  1  0.068  0.152  0.795  1.0
  O  O36  1  0.517  0.087  0.944  1.0
  O  O37  1  0.913  0.278  0.310  1.0
  O  O38  1  0.075  0.827  0.390  1.0
  O  O39  1  0.483  0.587  0.056  1.0
[/CIF]
.
The structure described by MgSiO3 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form MgO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(2) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. is represented by the CIF file [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.870
_cell_length_b   10.133
_cell_length_c   10.956
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   540.679
_cell_formula_units_Z   8
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Mg  Mg0  1  0.287  0.973  0.466  1.0
  Mg  Mg1  1  0.651  0.256  0.027  1.0
  Mg  Mg2  1  0.849  0.756  0.527  1.0
  Mg  Mg3  1  0.151  0.256  0.473  1.0
  Mg  Mg4  1  0.713  0.473  0.534  1.0
  Mg  Mg5  1  0.213  0.473  0.966  1.0
  Mg  Mg6  1  0.787  0.973  0.034  1.0
  Mg  Mg7  1  0.349  0.756  0.973  1.0
  Si  Si8  1  0.571  0.259  0.329  1.0
  Si  Si9  1  0.071  0.259  0.171  1.0
  Si  Si10  1  0.892  0.176  0.667  1.0
  Si  Si11  1  0.392  0.176  0.833  1.0
  Si  Si12  1  0.608  0.676  0.167  1.0
  Si  Si13  1  0.429  0.759  0.671  1.0
  Si  Si14  1  0.929  0.759  0.829  1.0
  Si  Si15  1  0.108  0.676  0.333  1.0
  O  O16  1  0.413  0.278  0.190  1.0
  O  O17  1  0.470  0.371  0.424  1.0
  O  O18  1  0.925  0.327  0.610  1.0
  O  O19  1  0.432  0.652  0.295  1.0
  O  O20  1  0.587  0.778  0.810  1.0
  O  O21  1  0.932  0.652  0.205  1.0
  O  O22  1  0.939  0.125  0.120  1.0
  O  O23  1  0.439  0.125  0.380  1.0
  O  O24  1  0.970  0.371  0.076  1.0
  O  O25  1  0.568  0.152  0.705  1.0
  O  O26  1  0.030  0.871  0.924  1.0
  O  O27  1  0.087  0.778  0.690  1.0
  O  O28  1  0.425  0.327  0.890  1.0
  O  O29  1  0.061  0.625  0.880  1.0
  O  O30  1  0.983  0.587  0.444  1.0
  O  O31  1  0.017  0.087  0.556  1.0
  O  O32  1  0.561  0.625  0.620  1.0
  O  O33  1  0.575  0.827  0.110  1.0
  O  O34  1  0.530  0.871  0.576  1.0
  O  O35  1  0.068  0.152  0.795  1.0
  O  O36  1  0.517  0.087  0.944  1.0
  O  O37  1  0.913  0.278  0.310  1.0
  O  O38  1  0.075  0.827  0.390  1.0
  O  O39  1  0.483  0.587  0.056  1.0
[/CIF]
.