The material described by Ba2Sr3CaMg2(SiO4)4 crystallizes in the monoclinic Pm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(12), one O(3), one O(8), one O(9), two equivalent O(10), two equivalent O(11), two equivalent O(2), and two equivalent O(5) atoms to form BaO12 cuboctahedra that share edges with two equivalent Ba(1)O12 cuboctahedra, edges with four equivalent Ba(2)O12 cuboctahedra,  an edgeedge with one Si(1)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra, edges with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Si(3)O4 tetrahedra, and faces with two equivalent Mg(1)O6 octahedra. In the second Ba site, Ba(2) is bonded to one O(10), one O(11), one O(4), one O(7), two equivalent O(1), two equivalent O(12), two equivalent O(6), and two equivalent O(9) atoms to form BaO12 cuboctahedra that share edges with two equivalent Ba(2)O12 cuboctahedra, edges with four equivalent Ba(1)O12 cuboctahedra,  an edgeedge with one Si(2)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, edges with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Si(4)O4 tetrahedra, and faces with two equivalent Mg(2)O6 octahedra. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 10-coordinate geometry to one O(10), one O(4), two equivalent O(2), two equivalent O(5), two equivalent O(6), and two equivalent O(8) atoms. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one O(11), one O(7), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the third Sr site, Sr(3) is bonded in a 10-coordinate geometry to one O(12), one O(8), two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. Ca(1) is bonded in a 10-coordinate geometry to one O(3), one O(9), two equivalent O(1), two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(8), two equivalent O(2), and two equivalent O(5) atoms to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. In the second Mg site, Mg(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(6) atoms to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and faces with two equivalent Ba(2)O12 cuboctahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(9), and two equivalent O(1) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Ba(1)O12 cuboctahedra, and edges with two equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the second Si site, Si(2) is bonded to one O(10), one O(4), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Ba(2)O12 cuboctahedra, and edges with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the third Si site, Si(3) is bonded to one O(11), one O(7), and two equivalent O(5) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Ba(2)O12 cuboctahedra, and edges with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the fourth Si site, Si(4) is bonded to one O(12), one O(8), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Ba(1)O12 cuboctahedra, and edges with two equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(2), one Sr(3), one Ca(1), one Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), one Sr(2), one Sr(3), one Mg(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Sr(2), one Ca(1), one Mg(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(1), two equivalent Sr(3), one Mg(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), one Sr(2), one Ca(1), one Mg(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(1), one Sr(3), one Ca(1), one Mg(2), and one Si(4) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(2), two equivalent Ca(1), one Mg(2), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(3), two equivalent Sr(1), one Mg(1), and one Si(4) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Ba(1), two equivalent Ba(2), one Ca(1), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted linear geometry to one Ba(2), two equivalent Ba(1), one Sr(1), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a distorted linear geometry to one Ba(2), two equivalent Ba(1), one Sr(2), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a distorted linear geometry to one Ba(1), two equivalent Ba(2), one Sr(3), and one Si(4) atom. is represented by the CIF card [CIF]
data_Ba2Sr3CaMg2(SiO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.545
_cell_length_b   7.046
_cell_length_c   9.600
_cell_angle_alpha   89.997
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   375.110
_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
  Ba  Ba0  1  0.500  0.500  0.000  1.0
  Ba  Ba1  1  0.000  0.501  0.500  1.0
  Sr  Sr2  1  0.000  0.838  0.833  1.0
  Sr  Sr3  1  0.000  0.162  0.167  1.0
  Sr  Sr4  1  0.500  0.162  0.666  1.0
  Ca  Ca5  1  0.500  0.831  0.333  1.0
  Mg  Mg6  1  0.500  1.000  0.001  1.0
  Mg  Mg7  1  0.000  1.000  0.499  1.0
  Si  Si8  1  0.500  0.273  0.333  1.0
  Si  Si9  1  0.000  0.271  0.833  1.0
  Si  Si10  1  0.000  0.729  0.168  1.0
  Si  Si11  1  0.500  0.729  0.665  1.0
  O  O12  1  0.737  0.178  0.412  1.0
  O  O13  1  0.238  0.177  0.913  1.0
  O  O14  1  0.263  0.178  0.412  1.0
  O  O15  1  0.762  0.177  0.913  1.0
  O  O16  1  0.500  0.178  0.175  1.0
  O  O17  1  0.000  0.177  0.675  1.0
  O  O18  1  0.761  0.823  0.090  1.0
  O  O19  1  0.264  0.823  0.585  1.0
  O  O20  1  0.239  0.823  0.090  1.0
  O  O21  1  0.736  0.823  0.585  1.0
  O  O22  1  0.000  0.823  0.326  1.0
  O  O23  1  0.500  0.823  0.824  1.0
  O  O24  1  0.500  0.504  0.333  1.0
  O  O25  1  0.000  0.499  0.833  1.0
  O  O26  1  0.000  0.500  0.167  1.0
  O  O27  1  0.500  0.500  0.666  1.0
[/CIF]
.
The material described by Ba2Sr3CaMg2(SiO4)4 crystallizes in the monoclinic Pm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(12), one O(3), one O(8), one O(9), two equivalent O(10), two equivalent O(11), two equivalent O(2), and two equivalent O(5) atoms to form BaO12 cuboctahedra that share edges with two equivalent Ba(1)O12 cuboctahedra, edges with four equivalent Ba(2)O12 cuboctahedra,  an edgeedge with one Si(1)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra, edges with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Si(3)O4 tetrahedra, and faces with two equivalent Mg(1)O6 octahedra. In the second Ba site, Ba(2) is bonded to one O(10), one O(11), one O(4), one O(7), two equivalent O(1), two equivalent O(12), two equivalent O(6), and two equivalent O(9) atoms to form BaO12 cuboctahedra that share edges with two equivalent Ba(2)O12 cuboctahedra, edges with four equivalent Ba(1)O12 cuboctahedra,  an edgeedge with one Si(2)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, edges with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Si(4)O4 tetrahedra, and faces with two equivalent Mg(2)O6 octahedra. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 10-coordinate geometry to one O(10), one O(4), two equivalent O(2), two equivalent O(5), two equivalent O(6), and two equivalent O(8) atoms. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to one O(11), one O(7), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the third Sr site, Sr(3) is bonded in a 10-coordinate geometry to one O(12), one O(8), two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. Ca(1) is bonded in a 10-coordinate geometry to one O(3), one O(9), two equivalent O(1), two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(8), two equivalent O(2), and two equivalent O(5) atoms to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. In the second Mg site, Mg(2) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(6) atoms to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and faces with two equivalent Ba(2)O12 cuboctahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(9), and two equivalent O(1) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Ba(1)O12 cuboctahedra, and edges with two equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the second Si site, Si(2) is bonded to one O(10), one O(4), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Ba(2)O12 cuboctahedra, and edges with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the third Si site, Si(3) is bonded to one O(11), one O(7), and two equivalent O(5) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Ba(2)O12 cuboctahedra, and edges with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the fourth Si site, Si(4) is bonded to one O(12), one O(8), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Ba(1)O12 cuboctahedra, and edges with two equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(2), one Sr(3), one Ca(1), one Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), one Sr(2), one Sr(3), one Mg(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Sr(2), one Ca(1), one Mg(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(1), two equivalent Sr(3), one Mg(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), one Sr(2), one Ca(1), one Mg(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(1), one Sr(3), one Ca(1), one Mg(2), and one Si(4) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ba(2), one Sr(2), two equivalent Ca(1), one Mg(2), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(3), two equivalent Sr(1), one Mg(1), and one Si(4) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Ba(1), two equivalent Ba(2), one Ca(1), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted linear geometry to one Ba(2), two equivalent Ba(1), one Sr(1), and one Si(2) atom. In the eleventh O site, O(11) is bonded in a distorted linear geometry to one Ba(2), two equivalent Ba(1), one Sr(2), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a distorted linear geometry to one Ba(1), two equivalent Ba(2), one Sr(3), and one Si(4) atom. is represented by the CIF card [CIF]
data_Ba2Sr3CaMg2(SiO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.545
_cell_length_b   7.046
_cell_length_c   9.600
_cell_angle_alpha   89.997
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   375.110
_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
  Ba  Ba0  1  0.500  0.500  0.000  1.0
  Ba  Ba1  1  0.000  0.501  0.500  1.0
  Sr  Sr2  1  0.000  0.838  0.833  1.0
  Sr  Sr3  1  0.000  0.162  0.167  1.0
  Sr  Sr4  1  0.500  0.162  0.666  1.0
  Ca  Ca5  1  0.500  0.831  0.333  1.0
  Mg  Mg6  1  0.500  1.000  0.001  1.0
  Mg  Mg7  1  0.000  1.000  0.499  1.0
  Si  Si8  1  0.500  0.273  0.333  1.0
  Si  Si9  1  0.000  0.271  0.833  1.0
  Si  Si10  1  0.000  0.729  0.168  1.0
  Si  Si11  1  0.500  0.729  0.665  1.0
  O  O12  1  0.737  0.178  0.412  1.0
  O  O13  1  0.238  0.177  0.913  1.0
  O  O14  1  0.263  0.178  0.412  1.0
  O  O15  1  0.762  0.177  0.913  1.0
  O  O16  1  0.500  0.178  0.175  1.0
  O  O17  1  0.000  0.177  0.675  1.0
  O  O18  1  0.761  0.823  0.090  1.0
  O  O19  1  0.264  0.823  0.585  1.0
  O  O20  1  0.239  0.823  0.090  1.0
  O  O21  1  0.736  0.823  0.585  1.0
  O  O22  1  0.000  0.823  0.326  1.0
  O  O23  1  0.500  0.823  0.824  1.0
  O  O24  1  0.500  0.504  0.333  1.0
  O  O25  1  0.000  0.499  0.833  1.0
  O  O26  1  0.000  0.500  0.167  1.0
  O  O27  1  0.500  0.500  0.666  1.0
[/CIF]
.