The structure described by Ca4MgSi8(NiO8)3 is Esseneite-derived structured and crystallizes in the monoclinic C2 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(11), two equivalent O(8), and two equivalent O(9) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(12), two equivalent O(2), and two equivalent O(7) atoms. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(3), one O(4), one O(5), one O(6), and one O(9) atom. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Si(3)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Si(4)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form NiO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Ni(1)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(11), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-59°. In the second Si site, Si(2) is bonded to one O(10), one O(12), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-59°. In the third Si site, Si(3) is bonded to one O(10), one O(11), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-58°. In the fourth Si site, Si(4) is bonded to one O(12), one O(4), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-59°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Mg(1), one Ni(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), one Ni(1), one Ni(2), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(3), one Mg(1), one Ni(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(3), one Ni(1), one Ni(2), and one Si(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ca(3), one Mg(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ca(3), one Ni(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(2), one Ni(2), and one Si(3) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ca(1), one Ni(2), and one Si(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(3), one Si(1), and one Si(4) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Ca(2), one Ca(3), one Si(2), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(3), one Si(1), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one Ca(2), one Ca(3), one Si(2), and one Si(4) atom. is represented by the CIF file [CIF]
data_Ca4MgSi8(NiO8)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.675
_cell_length_b   6.675
_cell_length_c   10.590
_cell_angle_alpha   78.259
_cell_angle_beta   78.259
_cell_angle_gamma   84.626
_symmetry_Int_Tables_number   1
_cell_volume   451.670
_cell_formula_units_Z   1
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
  Ca  Ca0  1  0.298  0.702  0.500  1.0
  Ca  Ca1  1  0.298  0.702  0.000  1.0
  Ca  Ca2  1  0.701  0.298  0.249  1.0
  Ca  Ca3  1  0.702  0.299  0.751  1.0
  Mg  Mg4  1  0.909  0.091  0.500  1.0
  Si  Si5  1  0.807  0.620  0.490  1.0
  Si  Si6  1  0.807  0.621  0.990  1.0
  Si  Si7  1  0.380  0.193  0.510  1.0
  Si  Si8  1  0.379  0.193  0.010  1.0
  Si  Si9  1  0.193  0.379  0.260  1.0
  Si  Si10  1  0.193  0.379  0.760  1.0
  Si  Si11  1  0.621  0.807  0.240  1.0
  Si  Si12  1  0.621  0.807  0.740  1.0
  Ni  Ni13  1  0.909  0.091  0.000  1.0
  Ni  Ni14  1  0.092  0.908  0.250  1.0
  Ni  Ni15  1  0.092  0.908  0.750  1.0
  O  O16  1  0.972  0.797  0.447  1.0
  O  O17  1  0.972  0.797  0.947  1.0
  O  O18  1  0.203  0.028  0.553  1.0
  O  O19  1  0.203  0.028  0.053  1.0
  O  O20  1  0.028  0.203  0.303  1.0
  O  O21  1  0.028  0.203  0.803  1.0
  O  O22  1  0.797  0.972  0.197  1.0
  O  O23  1  0.797  0.972  0.697  1.0
  O  O24  1  0.889  0.388  0.536  1.0
  O  O25  1  0.890  0.389  0.036  1.0
  O  O26  1  0.612  0.111  0.464  1.0
  O  O27  1  0.611  0.110  0.964  1.0
  O  O28  1  0.110  0.611  0.214  1.0
  O  O29  1  0.110  0.611  0.714  1.0
  O  O30  1  0.389  0.890  0.286  1.0
  O  O31  1  0.389  0.890  0.786  1.0
  O  O32  1  0.668  0.631  0.373  1.0
  O  O33  1  0.667  0.631  0.873  1.0
  O  O34  1  0.369  0.333  0.127  1.0
  O  O35  1  0.369  0.332  0.627  1.0
  O  O36  1  0.332  0.369  0.377  1.0
  O  O37  1  0.332  0.369  0.877  1.0
  O  O38  1  0.631  0.668  0.623  1.0
  O  O39  1  0.631  0.668  0.123  1.0
[/CIF]
.
The structure described by Ca4MgSi8(NiO8)3 is Esseneite-derived structured and crystallizes in the monoclinic C2 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(11), two equivalent O(8), and two equivalent O(9) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(12), two equivalent O(2), and two equivalent O(7) atoms. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(3), one O(4), one O(5), one O(6), and one O(9) atom. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Si(3)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form NiO6 octahedra that share corners with two equivalent Si(4)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with two equivalent Ni(2)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form NiO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Ni(1)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(11), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-59°. In the second Si site, Si(2) is bonded to one O(10), one O(12), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(2)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-59°. In the third Si site, Si(3) is bonded to one O(10), one O(11), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-58°. In the fourth Si site, Si(4) is bonded to one O(12), one O(4), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent Ni(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-59°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Mg(1), one Ni(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), one Ni(1), one Ni(2), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(3), one Mg(1), one Ni(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(3), one Ni(1), one Ni(2), and one Si(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ca(3), one Mg(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ca(3), one Ni(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(2), one Ni(2), and one Si(3) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ca(1), one Ni(2), and one Si(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(3), one Si(1), and one Si(4) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Ca(2), one Ca(3), one Si(2), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(3), one Si(1), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one Ca(2), one Ca(3), one Si(2), and one Si(4) atom. is represented by the CIF file [CIF]
data_Ca4MgSi8(NiO8)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.675
_cell_length_b   6.675
_cell_length_c   10.590
_cell_angle_alpha   78.259
_cell_angle_beta   78.259
_cell_angle_gamma   84.626
_symmetry_Int_Tables_number   1
_cell_volume   451.670
_cell_formula_units_Z   1
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
  Ca  Ca0  1  0.298  0.702  0.500  1.0
  Ca  Ca1  1  0.298  0.702  0.000  1.0
  Ca  Ca2  1  0.701  0.298  0.249  1.0
  Ca  Ca3  1  0.702  0.299  0.751  1.0
  Mg  Mg4  1  0.909  0.091  0.500  1.0
  Si  Si5  1  0.807  0.620  0.490  1.0
  Si  Si6  1  0.807  0.621  0.990  1.0
  Si  Si7  1  0.380  0.193  0.510  1.0
  Si  Si8  1  0.379  0.193  0.010  1.0
  Si  Si9  1  0.193  0.379  0.260  1.0
  Si  Si10  1  0.193  0.379  0.760  1.0
  Si  Si11  1  0.621  0.807  0.240  1.0
  Si  Si12  1  0.621  0.807  0.740  1.0
  Ni  Ni13  1  0.909  0.091  0.000  1.0
  Ni  Ni14  1  0.092  0.908  0.250  1.0
  Ni  Ni15  1  0.092  0.908  0.750  1.0
  O  O16  1  0.972  0.797  0.447  1.0
  O  O17  1  0.972  0.797  0.947  1.0
  O  O18  1  0.203  0.028  0.553  1.0
  O  O19  1  0.203  0.028  0.053  1.0
  O  O20  1  0.028  0.203  0.303  1.0
  O  O21  1  0.028  0.203  0.803  1.0
  O  O22  1  0.797  0.972  0.197  1.0
  O  O23  1  0.797  0.972  0.697  1.0
  O  O24  1  0.889  0.388  0.536  1.0
  O  O25  1  0.890  0.389  0.036  1.0
  O  O26  1  0.612  0.111  0.464  1.0
  O  O27  1  0.611  0.110  0.964  1.0
  O  O28  1  0.110  0.611  0.214  1.0
  O  O29  1  0.110  0.611  0.714  1.0
  O  O30  1  0.389  0.890  0.286  1.0
  O  O31  1  0.389  0.890  0.786  1.0
  O  O32  1  0.668  0.631  0.373  1.0
  O  O33  1  0.667  0.631  0.873  1.0
  O  O34  1  0.369  0.333  0.127  1.0
  O  O35  1  0.369  0.332  0.627  1.0
  O  O36  1  0.332  0.369  0.377  1.0
  O  O37  1  0.332  0.369  0.877  1.0
  O  O38  1  0.631  0.668  0.623  1.0
  O  O39  1  0.631  0.668  0.123  1.0
[/CIF]
.