The material described by Na2MgSi5O12 is Esseneite-like structured and crystallizes in the monoclinic P2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. Mg(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Si(3)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-69°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Si(3)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-64°. In the third Si site, Si(3) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form SiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(6) is bonded in a distorted T-shaped geometry to one Na(2), one Si(2), and one Si(3) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Si(1), and one Si(2) atom. In the third O site, O(2) is bonded in a distorted T-shaped geometry to one Na(1), one Mg(1), and one Si(1) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Mg(1), one Si(1), and one Si(3) atom. In the sixth O site, O(5) is bonded to one Na(2), one Mg(1), one Si(2), and one Si(3) atom to form a mixture of distorted edge and corner-sharing ONaMgSi2 tetrahedra. is represented by the CIF card [CIF]
data_Na2MgSi5O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.738
_cell_length_b   5.334
_cell_length_c   9.345
_cell_angle_alpha   75.455
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   421.582
_cell_formula_units_Z   2
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
  Na  Na0  1  0.543  0.000  0.750  1.0
  Na  Na1  1  0.457  0.000  0.250  1.0
  Na  Na2  1  0.949  0.500  0.750  1.0
  Na  Na3  1  0.051  0.500  0.250  1.0
  Mg  Mg4  1  0.346  0.500  0.750  1.0
  Mg  Mg5  1  0.654  0.500  0.250  1.0
  Si  Si6  1  0.666  0.302  0.963  1.0
  Si  Si7  1  0.151  0.181  0.044  1.0
  Si  Si8  1  0.151  0.819  0.456  1.0
  Si  Si9  1  0.334  0.302  0.463  1.0
  Si  Si10  1  0.849  0.819  0.956  1.0
  Si  Si11  1  0.334  0.698  0.037  1.0
  Si  Si12  1  0.849  0.181  0.544  1.0
  Si  Si13  1  0.152  0.000  0.750  1.0
  Si  Si14  1  0.666  0.698  0.537  1.0
  Si  Si15  1  0.848  0.000  0.250  1.0
  O  O16  1  0.246  0.586  0.409  1.0
  O  O17  1  0.504  0.309  0.402  1.0
  O  O18  1  0.754  0.414  0.591  1.0
  O  O19  1  0.504  0.691  0.098  1.0
  O  O20  1  0.766  0.899  0.612  1.0
  O  O21  1  0.306  0.200  0.644  1.0
  O  O22  1  0.156  0.761  0.638  1.0
  O  O23  1  0.694  0.800  0.356  1.0
  O  O24  1  0.694  0.200  0.144  1.0
  O  O25  1  0.754  0.586  0.909  1.0
  O  O26  1  0.234  0.899  0.112  1.0
  O  O27  1  0.246  0.414  0.091  1.0
  O  O28  1  0.306  0.800  0.856  1.0
  O  O29  1  0.496  0.309  0.902  1.0
  O  O30  1  0.844  0.239  0.362  1.0
  O  O31  1  0.234  0.101  0.388  1.0
  O  O32  1  0.986  0.818  0.376  1.0
  O  O33  1  0.986  0.182  0.124  1.0
  O  O34  1  0.014  0.818  0.876  1.0
  O  O35  1  0.496  0.691  0.598  1.0
  O  O36  1  0.014  0.182  0.624  1.0
  O  O37  1  0.156  0.239  0.862  1.0
  O  O38  1  0.766  0.101  0.888  1.0
  O  O39  1  0.844  0.761  0.138  1.0
[/CIF]
.
The material described by Na2MgSi5O12 is Esseneite-like structured and crystallizes in the monoclinic P2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. Mg(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Si(3)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-69°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Si(3)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-64°. In the third Si site, Si(3) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form SiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(6) is bonded in a distorted T-shaped geometry to one Na(2), one Si(2), and one Si(3) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Si(1), and one Si(2) atom. In the third O site, O(2) is bonded in a distorted T-shaped geometry to one Na(1), one Mg(1), and one Si(1) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Mg(1), one Si(1), and one Si(3) atom. In the sixth O site, O(5) is bonded to one Na(2), one Mg(1), one Si(2), and one Si(3) atom to form a mixture of distorted edge and corner-sharing ONaMgSi2 tetrahedra. is represented by the CIF card [CIF]
data_Na2MgSi5O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.738
_cell_length_b   5.334
_cell_length_c   9.345
_cell_angle_alpha   75.455
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   421.582
_cell_formula_units_Z   2
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
  Na  Na0  1  0.543  0.000  0.750  1.0
  Na  Na1  1  0.457  0.000  0.250  1.0
  Na  Na2  1  0.949  0.500  0.750  1.0
  Na  Na3  1  0.051  0.500  0.250  1.0
  Mg  Mg4  1  0.346  0.500  0.750  1.0
  Mg  Mg5  1  0.654  0.500  0.250  1.0
  Si  Si6  1  0.666  0.302  0.963  1.0
  Si  Si7  1  0.151  0.181  0.044  1.0
  Si  Si8  1  0.151  0.819  0.456  1.0
  Si  Si9  1  0.334  0.302  0.463  1.0
  Si  Si10  1  0.849  0.819  0.956  1.0
  Si  Si11  1  0.334  0.698  0.037  1.0
  Si  Si12  1  0.849  0.181  0.544  1.0
  Si  Si13  1  0.152  0.000  0.750  1.0
  Si  Si14  1  0.666  0.698  0.537  1.0
  Si  Si15  1  0.848  0.000  0.250  1.0
  O  O16  1  0.246  0.586  0.409  1.0
  O  O17  1  0.504  0.309  0.402  1.0
  O  O18  1  0.754  0.414  0.591  1.0
  O  O19  1  0.504  0.691  0.098  1.0
  O  O20  1  0.766  0.899  0.612  1.0
  O  O21  1  0.306  0.200  0.644  1.0
  O  O22  1  0.156  0.761  0.638  1.0
  O  O23  1  0.694  0.800  0.356  1.0
  O  O24  1  0.694  0.200  0.144  1.0
  O  O25  1  0.754  0.586  0.909  1.0
  O  O26  1  0.234  0.899  0.112  1.0
  O  O27  1  0.246  0.414  0.091  1.0
  O  O28  1  0.306  0.800  0.856  1.0
  O  O29  1  0.496  0.309  0.902  1.0
  O  O30  1  0.844  0.239  0.362  1.0
  O  O31  1  0.234  0.101  0.388  1.0
  O  O32  1  0.986  0.818  0.376  1.0
  O  O33  1  0.986  0.182  0.124  1.0
  O  O34  1  0.014  0.818  0.876  1.0
  O  O35  1  0.496  0.691  0.598  1.0
  O  O36  1  0.014  0.182  0.624  1.0
  O  O37  1  0.156  0.239  0.862  1.0
  O  O38  1  0.766  0.101  0.888  1.0
  O  O39  1  0.844  0.761  0.138  1.0
[/CIF]
.