The material structure described by CaMg7(SiO3)8 crystallizes in the triclinic P1 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(10), one O(16), one O(18), one O(19), one O(24), one O(3), and one O(5) atom. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(10), one O(11), one O(2), one O(21), one O(5), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra, and edges with two equivalent Mg(4)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(12), one O(22), one O(6), one O(7), and one O(9) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, and edges with two equivalent Mg(6)O6 octahedra. In the third Mg site, Mg(3) is bonded to one O(12), one O(23), one O(4), one O(6), one O(7), and one O(9) atom to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(6)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with two equivalent Mg(5)O6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(10), one O(11), one O(24), one O(3), one O(5), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. In the fifth Mg site, Mg(5) is bonded to one O(15), one O(17), one O(23), one O(4), one O(6), and one O(9) atom to form distorted MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, and  an edgeedge with one Si(7)O4 tetrahedra. In the sixth Mg site, Mg(6) is bonded to one O(1), one O(12), one O(14), one O(20), one O(22), and one O(7) atom to form distorted MgO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(6)O4 tetrahedra. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one O(11), one O(13), one O(2), one O(21), and one O(8) atom. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(17), one O(20), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, corners with two equivalent Mg(6)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-76°. In the second Si site, Si(2) is bonded to one O(18), one O(19), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-61°. In the third Si site, Si(3) is bonded to one O(18), one O(19), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-60°. In the fourth Si site, Si(4) is bonded to one O(17), one O(20), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, corners with two equivalent Mg(5)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-75°. In the fifth Si site, Si(5) is bonded to one O(13), one O(16), one O(21), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, and corners with two equivalent Si(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-61°. In the sixth Si site, Si(6) is bonded to one O(10), one O(14), one O(15), and one O(22) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, corners with two equivalent Si(7)O4 tetrahedra, and  an edgeedge with one Mg(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-58°. In the seventh Si site, Si(7) is bonded to one O(11), one O(14), one O(15), and one O(23) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, corners with two equivalent Si(6)O4 tetrahedra, and  an edgeedge with one Mg(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-61°. In the eighth Si site, Si(8) is bonded to one O(12), one O(13), one O(16), and one O(24) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, and corners with two equivalent Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-61°. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mg(6), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(7), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Mg(4), and one Si(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(3), one Mg(5), and one Si(4) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one Mg(4), and one Si(1) atom. In the sixth O site, O(6) is bonded to one Mg(2), one Mg(3), one Mg(5), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the seventh O site, O(7) is bonded to one Mg(2), one Mg(3), one Mg(6), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(4), one Mg(7), and one Si(4) atom. In the ninth O site, O(9) is bonded to one Mg(2), one Mg(3), one Mg(5), and one Si(5) atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the tenth O site, O(10) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one Mg(4), and one Si(6) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Mg(4), one Mg(7), and one Si(7) atom. In the twelfth O site, O(12) is bonded to one Mg(2), one Mg(3), one Mg(6), and one Si(8) atom to form a mixture of distorted corner and edge-sharing OMg3Si tetrahedra. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Mg(7), one Si(5), and one Si(8) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Mg(6), one Si(6), and one Si(7) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Mg(5), one Si(6), and one Si(7) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Ca(1), one Si(5), and one Si(8) atom. In the seventeenth O site, O(17) is bonded in a 2-coordinate geometry to one Mg(5), one Si(1), and one Si(4) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one Ca(1), one Si(2), and one Si(3) atom. In the nineteenth O site, O(19) is bonded in a 2-coordinate geometry to one Ca(1), one Si(2), and one Si(3) atom. In the twentieth O site, O(20) is bonded in a distorted bent 120 degrees geometry to one Mg(6), one Si(1), and one Si(4) atom. In the twenty-first O site, O(21) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(7), and one Si(5) atom. In the twenty-second O site, O(22) is bonded in a distorted T-shaped geometry to one Mg(2), one Mg(6), and one Si(6) atom. In the twenty-third O site, O(23) is bonded in a distorted T-shaped geometry to one Mg(3), one Mg(5), and one Si(7) atom. In the twenty-fourth O site, O(24) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(4), and one Si(8) atom. is represented by the CIF card [CIF]
data_CaMg7(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.299
_cell_length_b   8.983
_cell_length_c   9.550
_cell_angle_alpha   89.686
_cell_angle_beta   76.905
_cell_angle_gamma   89.896
_symmetry_Int_Tables_number   1
_cell_volume   442.777
_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  0.529  0.537  0.739  1.0
  Mg  Mg1  1  0.522  0.154  0.749  1.0
  Mg  Mg2  1  0.978  0.651  0.251  1.0
  Mg  Mg3  1  0.477  0.849  0.251  1.0
  Mg  Mg4  1  0.019  0.343  0.750  1.0
  Mg  Mg5  1  0.971  0.012  0.251  1.0
  Mg  Mg6  1  0.472  0.489  0.252  1.0
  Mg  Mg7  1  0.026  0.992  0.750  1.0
  Si  Si8  1  0.812  0.335  0.450  1.0
  Si  Si9  1  0.689  0.843  0.547  1.0
  Si  Si10  1  0.184  0.661  0.543  1.0
  Si  Si11  1  0.310  0.161  0.450  1.0
  Si  Si12  1  0.261  0.844  0.959  1.0
  Si  Si13  1  0.240  0.339  0.043  1.0
  Si  Si14  1  0.741  0.159  0.044  1.0
  Si  Si15  1  0.767  0.659  0.963  1.0
  O  O16  1  0.749  0.486  0.370  1.0
  O  O17  1  0.747  0.987  0.634  1.0
  O  O18  1  0.217  0.505  0.619  1.0
  O  O19  1  0.249  0.013  0.368  1.0
  O  O20  1  0.744  0.331  0.625  1.0
  O  O21  1  0.759  0.845  0.372  1.0
  O  O22  1  0.261  0.661  0.368  1.0
  O  O23  1  0.240  0.155  0.626  1.0
  O  O24  1  0.191  0.843  0.134  1.0
  O  O25  1  0.302  0.334  0.868  1.0
  O  O26  1  0.806  0.157  0.868  1.0
  O  O27  1  0.694  0.661  0.139  1.0
  O  O28  1  0.017  0.771  0.897  1.0
  O  O29  1  0.490  0.270  0.105  1.0
  O  O30  1  0.988  0.228  0.108  1.0
  O  O31  1  0.520  0.736  0.904  1.0
  O  O32  1  0.627  0.203  0.396  1.0
  O  O33  1  0.873  0.710  0.599  1.0
  O  O34  1  0.378  0.785  0.602  1.0
  O  O35  1  0.129  0.295  0.395  1.0
  O  O36  1  0.292  0.001  0.875  1.0
  O  O37  1  0.209  0.499  0.122  1.0
  O  O38  1  0.708  0.999  0.123  1.0
  O  O39  1  0.811  0.499  0.889  1.0
[/CIF]
.
The material structure described by CaMg7(SiO3)8 crystallizes in the triclinic P1 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(10), one O(16), one O(18), one O(19), one O(24), one O(3), and one O(5) atom. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(10), one O(11), one O(2), one O(21), one O(5), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra, and edges with two equivalent Mg(4)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(12), one O(22), one O(6), one O(7), and one O(9) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, and edges with two equivalent Mg(6)O6 octahedra. In the third Mg site, Mg(3) is bonded to one O(12), one O(23), one O(4), one O(6), one O(7), and one O(9) atom to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(6)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with two equivalent Mg(5)O6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(10), one O(11), one O(24), one O(3), one O(5), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. In the fifth Mg site, Mg(5) is bonded to one O(15), one O(17), one O(23), one O(4), one O(6), and one O(9) atom to form distorted MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, and  an edgeedge with one Si(7)O4 tetrahedra. In the sixth Mg site, Mg(6) is bonded to one O(1), one O(12), one O(14), one O(20), one O(22), and one O(7) atom to form distorted MgO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(6)O4 tetrahedra. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one O(11), one O(13), one O(2), one O(21), and one O(8) atom. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(17), one O(20), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, corners with two equivalent Mg(6)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-76°. In the second Si site, Si(2) is bonded to one O(18), one O(19), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-61°. In the third Si site, Si(3) is bonded to one O(18), one O(19), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-60°. In the fourth Si site, Si(4) is bonded to one O(17), one O(20), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, corners with two equivalent Mg(5)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-75°. In the fifth Si site, Si(5) is bonded to one O(13), one O(16), one O(21), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, and corners with two equivalent Si(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-61°. In the sixth Si site, Si(6) is bonded to one O(10), one O(14), one O(15), and one O(22) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra, corners with two equivalent Si(7)O4 tetrahedra, and  an edgeedge with one Mg(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-58°. In the seventh Si site, Si(7) is bonded to one O(11), one O(14), one O(15), and one O(23) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, corners with two equivalent Si(6)O4 tetrahedra, and  an edgeedge with one Mg(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-61°. In the eighth Si site, Si(8) is bonded to one O(12), one O(13), one O(16), and one O(24) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(6)O6 octahedra, and corners with two equivalent Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 26-61°. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(2), one Mg(6), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(7), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Mg(4), and one Si(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(3), one Mg(5), and one Si(4) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one Mg(4), and one Si(1) atom. In the sixth O site, O(6) is bonded to one Mg(2), one Mg(3), one Mg(5), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the seventh O site, O(7) is bonded to one Mg(2), one Mg(3), one Mg(6), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(4), one Mg(7), and one Si(4) atom. In the ninth O site, O(9) is bonded to one Mg(2), one Mg(3), one Mg(5), and one Si(5) atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the tenth O site, O(10) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one Mg(4), and one Si(6) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Mg(4), one Mg(7), and one Si(7) atom. In the twelfth O site, O(12) is bonded to one Mg(2), one Mg(3), one Mg(6), and one Si(8) atom to form a mixture of distorted corner and edge-sharing OMg3Si tetrahedra. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Mg(7), one Si(5), and one Si(8) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Mg(6), one Si(6), and one Si(7) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Mg(5), one Si(6), and one Si(7) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Ca(1), one Si(5), and one Si(8) atom. In the seventeenth O site, O(17) is bonded in a 2-coordinate geometry to one Mg(5), one Si(1), and one Si(4) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one Ca(1), one Si(2), and one Si(3) atom. In the nineteenth O site, O(19) is bonded in a 2-coordinate geometry to one Ca(1), one Si(2), and one Si(3) atom. In the twentieth O site, O(20) is bonded in a distorted bent 120 degrees geometry to one Mg(6), one Si(1), and one Si(4) atom. In the twenty-first O site, O(21) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(7), and one Si(5) atom. In the twenty-second O site, O(22) is bonded in a distorted T-shaped geometry to one Mg(2), one Mg(6), and one Si(6) atom. In the twenty-third O site, O(23) is bonded in a distorted T-shaped geometry to one Mg(3), one Mg(5), and one Si(7) atom. In the twenty-fourth O site, O(24) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(4), and one Si(8) atom. is represented by the CIF card [CIF]
data_CaMg7(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.299
_cell_length_b   8.983
_cell_length_c   9.550
_cell_angle_alpha   89.686
_cell_angle_beta   76.905
_cell_angle_gamma   89.896
_symmetry_Int_Tables_number   1
_cell_volume   442.777
_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  0.529  0.537  0.739  1.0
  Mg  Mg1  1  0.522  0.154  0.749  1.0
  Mg  Mg2  1  0.978  0.651  0.251  1.0
  Mg  Mg3  1  0.477  0.849  0.251  1.0
  Mg  Mg4  1  0.019  0.343  0.750  1.0
  Mg  Mg5  1  0.971  0.012  0.251  1.0
  Mg  Mg6  1  0.472  0.489  0.252  1.0
  Mg  Mg7  1  0.026  0.992  0.750  1.0
  Si  Si8  1  0.812  0.335  0.450  1.0
  Si  Si9  1  0.689  0.843  0.547  1.0
  Si  Si10  1  0.184  0.661  0.543  1.0
  Si  Si11  1  0.310  0.161  0.450  1.0
  Si  Si12  1  0.261  0.844  0.959  1.0
  Si  Si13  1  0.240  0.339  0.043  1.0
  Si  Si14  1  0.741  0.159  0.044  1.0
  Si  Si15  1  0.767  0.659  0.963  1.0
  O  O16  1  0.749  0.486  0.370  1.0
  O  O17  1  0.747  0.987  0.634  1.0
  O  O18  1  0.217  0.505  0.619  1.0
  O  O19  1  0.249  0.013  0.368  1.0
  O  O20  1  0.744  0.331  0.625  1.0
  O  O21  1  0.759  0.845  0.372  1.0
  O  O22  1  0.261  0.661  0.368  1.0
  O  O23  1  0.240  0.155  0.626  1.0
  O  O24  1  0.191  0.843  0.134  1.0
  O  O25  1  0.302  0.334  0.868  1.0
  O  O26  1  0.806  0.157  0.868  1.0
  O  O27  1  0.694  0.661  0.139  1.0
  O  O28  1  0.017  0.771  0.897  1.0
  O  O29  1  0.490  0.270  0.105  1.0
  O  O30  1  0.988  0.228  0.108  1.0
  O  O31  1  0.520  0.736  0.904  1.0
  O  O32  1  0.627  0.203  0.396  1.0
  O  O33  1  0.873  0.710  0.599  1.0
  O  O34  1  0.378  0.785  0.602  1.0
  O  O35  1  0.129  0.295  0.395  1.0
  O  O36  1  0.292  0.001  0.875  1.0
  O  O37  1  0.209  0.499  0.122  1.0
  O  O38  1  0.708  0.999  0.123  1.0
  O  O39  1  0.811  0.499  0.889  1.0
[/CIF]
.