The crystal structure described by MgSiO3 crystallizes in the orthorhombic Pbcn space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with three equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with three equivalent Mg(1)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-60°. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Si(1) atoms. In the third O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.312
_cell_length_b   8.712
_cell_length_c   9.267
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   428.862
_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  0.250  0.904  0.000  1.0
  Mg  Mg1  1  0.750  0.596  0.500  1.0
  Mg  Mg2  1  0.750  0.096  0.000  1.0
  Mg  Mg3  1  0.250  0.404  0.500  1.0
  Mg  Mg4  1  0.750  0.737  0.000  1.0
  Mg  Mg5  1  0.250  0.763  0.500  1.0
  Mg  Mg6  1  0.250  0.263  0.000  1.0
  Mg  Mg7  1  0.750  0.237  0.500  1.0
  Si  Si8  1  0.935  0.909  0.292  1.0
  Si  Si9  1  0.435  0.591  0.208  1.0
  Si  Si10  1  0.565  0.909  0.708  1.0
  Si  Si11  1  0.065  0.591  0.792  1.0
  Si  Si12  1  0.065  0.091  0.708  1.0
  Si  Si13  1  0.565  0.409  0.792  1.0
  Si  Si14  1  0.435  0.091  0.292  1.0
  Si  Si15  1  0.935  0.409  0.208  1.0
  O  O16  1  0.712  0.526  0.151  1.0
  O  O17  1  0.212  0.974  0.349  1.0
  O  O18  1  0.788  0.526  0.849  1.0
  O  O19  1  0.288  0.974  0.651  1.0
  O  O20  1  0.288  0.474  0.849  1.0
  O  O21  1  0.788  0.026  0.651  1.0
  O  O22  1  0.212  0.474  0.151  1.0
  O  O23  1  0.712  0.026  0.349  1.0
  O  O24  1  0.930  0.250  0.123  1.0
  O  O25  1  0.430  0.250  0.377  1.0
  O  O26  1  0.570  0.250  0.877  1.0
  O  O27  1  0.070  0.250  0.623  1.0
  O  O28  1  0.070  0.750  0.877  1.0
  O  O29  1  0.570  0.750  0.623  1.0
  O  O30  1  0.430  0.750  0.123  1.0
  O  O31  1  0.930  0.750  0.377  1.0
  O  O32  1  0.922  0.906  0.118  1.0
  O  O33  1  0.422  0.594  0.382  1.0
  O  O34  1  0.578  0.906  0.882  1.0
  O  O35  1  0.078  0.594  0.618  1.0
  O  O36  1  0.078  0.094  0.882  1.0
  O  O37  1  0.578  0.406  0.618  1.0
  O  O38  1  0.422  0.094  0.118  1.0
  O  O39  1  0.922  0.406  0.382  1.0
[/CIF]
.
The crystal structure described by MgSiO3 crystallizes in the orthorhombic Pbcn space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with three equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with three equivalent Mg(1)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-60°. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Si(1) atoms. In the third O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.312
_cell_length_b   8.712
_cell_length_c   9.267
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   428.862
_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  0.250  0.904  0.000  1.0
  Mg  Mg1  1  0.750  0.596  0.500  1.0
  Mg  Mg2  1  0.750  0.096  0.000  1.0
  Mg  Mg3  1  0.250  0.404  0.500  1.0
  Mg  Mg4  1  0.750  0.737  0.000  1.0
  Mg  Mg5  1  0.250  0.763  0.500  1.0
  Mg  Mg6  1  0.250  0.263  0.000  1.0
  Mg  Mg7  1  0.750  0.237  0.500  1.0
  Si  Si8  1  0.935  0.909  0.292  1.0
  Si  Si9  1  0.435  0.591  0.208  1.0
  Si  Si10  1  0.565  0.909  0.708  1.0
  Si  Si11  1  0.065  0.591  0.792  1.0
  Si  Si12  1  0.065  0.091  0.708  1.0
  Si  Si13  1  0.565  0.409  0.792  1.0
  Si  Si14  1  0.435  0.091  0.292  1.0
  Si  Si15  1  0.935  0.409  0.208  1.0
  O  O16  1  0.712  0.526  0.151  1.0
  O  O17  1  0.212  0.974  0.349  1.0
  O  O18  1  0.788  0.526  0.849  1.0
  O  O19  1  0.288  0.974  0.651  1.0
  O  O20  1  0.288  0.474  0.849  1.0
  O  O21  1  0.788  0.026  0.651  1.0
  O  O22  1  0.212  0.474  0.151  1.0
  O  O23  1  0.712  0.026  0.349  1.0
  O  O24  1  0.930  0.250  0.123  1.0
  O  O25  1  0.430  0.250  0.377  1.0
  O  O26  1  0.570  0.250  0.877  1.0
  O  O27  1  0.070  0.250  0.623  1.0
  O  O28  1  0.070  0.750  0.877  1.0
  O  O29  1  0.570  0.750  0.623  1.0
  O  O30  1  0.430  0.750  0.123  1.0
  O  O31  1  0.930  0.750  0.377  1.0
  O  O32  1  0.922  0.906  0.118  1.0
  O  O33  1  0.422  0.594  0.382  1.0
  O  O34  1  0.578  0.906  0.882  1.0
  O  O35  1  0.078  0.594  0.618  1.0
  O  O36  1  0.078  0.094  0.882  1.0
  O  O37  1  0.578  0.406  0.618  1.0
  O  O38  1  0.422  0.094  0.118  1.0
  O  O39  1  0.922  0.406  0.382  1.0
[/CIF]
.