The material described by KMg3(SiO3)4 crystallizes in the monoclinic C2/m space group. K(1) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form KO12 cuboctahedra that share edges with six equivalent K(1)O12 cuboctahedra and edges with twelve equivalent Si(1)O4 tetrahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with three 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(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with six equivalent Mg(1)O6 octahedra. Si(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with three equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 54-58°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2) and two equivalent Mg(1) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KMg3(SiO3)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.319
_cell_length_b   5.319
_cell_length_c   10.372
_cell_angle_alpha   85.736
_cell_angle_beta   85.736
_cell_angle_gamma   120.823
_symmetry_Int_Tables_number   1
_cell_volume   249.164
_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
  K  K0  1  0.000  0.000  0.000  1.0
  Mg  Mg1  1  0.834  0.166  0.500  1.0
  Mg  Mg2  1  0.166  0.834  0.500  1.0
  Mg  Mg3  1  0.500  0.500  0.500  1.0
  Si  Si4  1  0.592  0.258  0.230  1.0
  Si  Si5  1  0.408  0.742  0.770  1.0
  Si  Si6  1  0.742  0.408  0.770  1.0
  Si  Si7  1  0.258  0.592  0.230  1.0
  O  O8  1  0.469  0.469  0.170  1.0
  O  O9  1  0.531  0.531  0.830  1.0
  O  O10  1  0.872  0.872  0.408  1.0
  O  O11  1  0.128  0.128  0.592  1.0
  O  O12  1  0.418  0.944  0.165  1.0
  O  O13  1  0.582  0.056  0.835  1.0
  O  O14  1  0.056  0.582  0.835  1.0
  O  O15  1  0.944  0.418  0.165  1.0
  O  O16  1  0.553  0.212  0.386  1.0
  O  O17  1  0.447  0.788  0.614  1.0
  O  O18  1  0.788  0.447  0.614  1.0
  O  O19  1  0.212  0.553  0.386  1.0
[/CIF]
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The material described by KMg3(SiO3)4 crystallizes in the monoclinic C2/m space group. K(1) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form KO12 cuboctahedra that share edges with six equivalent K(1)O12 cuboctahedra and edges with twelve equivalent Si(1)O4 tetrahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with three 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(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with six equivalent Mg(1)O6 octahedra. Si(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with three equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 54-58°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2) and two equivalent Mg(1) atoms. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KMg3(SiO3)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.319
_cell_length_b   5.319
_cell_length_c   10.372
_cell_angle_alpha   85.736
_cell_angle_beta   85.736
_cell_angle_gamma   120.823
_symmetry_Int_Tables_number   1
_cell_volume   249.164
_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
  K  K0  1  0.000  0.000  0.000  1.0
  Mg  Mg1  1  0.834  0.166  0.500  1.0
  Mg  Mg2  1  0.166  0.834  0.500  1.0
  Mg  Mg3  1  0.500  0.500  0.500  1.0
  Si  Si4  1  0.592  0.258  0.230  1.0
  Si  Si5  1  0.408  0.742  0.770  1.0
  Si  Si6  1  0.742  0.408  0.770  1.0
  Si  Si7  1  0.258  0.592  0.230  1.0
  O  O8  1  0.469  0.469  0.170  1.0
  O  O9  1  0.531  0.531  0.830  1.0
  O  O10  1  0.872  0.872  0.408  1.0
  O  O11  1  0.128  0.128  0.592  1.0
  O  O12  1  0.418  0.944  0.165  1.0
  O  O13  1  0.582  0.056  0.835  1.0
  O  O14  1  0.056  0.582  0.835  1.0
  O  O15  1  0.944  0.418  0.165  1.0
  O  O16  1  0.553  0.212  0.386  1.0
  O  O17  1  0.447  0.788  0.614  1.0
  O  O18  1  0.788  0.447  0.614  1.0
  O  O19  1  0.212  0.553  0.386  1.0
[/CIF]
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