The compound described by Mg2SiO4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Mg(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-62°. In the second Mg site, Mg(2) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form MgO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-62°. 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(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and one Si(1) atom to form distorted corner-sharing OMg3Si trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.751
_cell_length_b   5.970
_cell_length_c   10.183
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   288.812
_cell_formula_units_Z   4
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  0.000  0.000  0.000  1.0
  Mg  Mg1  1  0.500  0.000  0.500  1.0
  Mg  Mg2  1  0.000  0.500  0.000  1.0
  Mg  Mg3  1  0.500  0.500  0.500  1.0
  Mg  Mg4  1  0.008  0.750  0.723  1.0
  Mg  Mg5  1  0.508  0.250  0.777  1.0
  Mg  Mg6  1  0.992  0.250  0.277  1.0
  Mg  Mg7  1  0.492  0.750  0.223  1.0
  Si  Si8  1  0.926  0.750  0.406  1.0
  Si  Si9  1  0.426  0.250  0.094  1.0
  Si  Si10  1  0.074  0.250  0.594  1.0
  Si  Si11  1  0.574  0.750  0.906  1.0
  O  O12  1  0.277  0.468  0.163  1.0
  O  O13  1  0.777  0.532  0.337  1.0
  O  O14  1  0.723  0.968  0.837  1.0
  O  O15  1  0.223  0.032  0.663  1.0
  O  O16  1  0.723  0.532  0.837  1.0
  O  O17  1  0.223  0.468  0.663  1.0
  O  O18  1  0.277  0.032  0.163  1.0
  O  O19  1  0.777  0.968  0.337  1.0
  O  O20  1  0.778  0.750  0.554  1.0
  O  O21  1  0.278  0.250  0.946  1.0
  O  O22  1  0.222  0.250  0.446  1.0
  O  O23  1  0.722  0.750  0.054  1.0
  O  O24  1  0.267  0.750  0.409  1.0
  O  O25  1  0.767  0.250  0.091  1.0
  O  O26  1  0.733  0.250  0.591  1.0
  O  O27  1  0.233  0.750  0.909  1.0
[/CIF]
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The compound described by Mg2SiO4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Mg(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-62°. In the second Mg site, Mg(2) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form MgO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-62°. 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(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), two equivalent Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and one Si(1) atom to form distorted corner-sharing OMg3Si trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.751
_cell_length_b   5.970
_cell_length_c   10.183
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   288.812
_cell_formula_units_Z   4
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  0.000  0.000  0.000  1.0
  Mg  Mg1  1  0.500  0.000  0.500  1.0
  Mg  Mg2  1  0.000  0.500  0.000  1.0
  Mg  Mg3  1  0.500  0.500  0.500  1.0
  Mg  Mg4  1  0.008  0.750  0.723  1.0
  Mg  Mg5  1  0.508  0.250  0.777  1.0
  Mg  Mg6  1  0.992  0.250  0.277  1.0
  Mg  Mg7  1  0.492  0.750  0.223  1.0
  Si  Si8  1  0.926  0.750  0.406  1.0
  Si  Si9  1  0.426  0.250  0.094  1.0
  Si  Si10  1  0.074  0.250  0.594  1.0
  Si  Si11  1  0.574  0.750  0.906  1.0
  O  O12  1  0.277  0.468  0.163  1.0
  O  O13  1  0.777  0.532  0.337  1.0
  O  O14  1  0.723  0.968  0.837  1.0
  O  O15  1  0.223  0.032  0.663  1.0
  O  O16  1  0.723  0.532  0.837  1.0
  O  O17  1  0.223  0.468  0.663  1.0
  O  O18  1  0.277  0.032  0.163  1.0
  O  O19  1  0.777  0.968  0.337  1.0
  O  O20  1  0.778  0.750  0.554  1.0
  O  O21  1  0.278  0.250  0.946  1.0
  O  O22  1  0.222  0.250  0.446  1.0
  O  O23  1  0.722  0.750  0.054  1.0
  O  O24  1  0.267  0.750  0.409  1.0
  O  O25  1  0.767  0.250  0.091  1.0
  O  O26  1  0.733  0.250  0.591  1.0
  O  O27  1  0.233  0.750  0.909  1.0
[/CIF]
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