The structure described by Ca3SiO5 crystallizes in the monoclinic Cm space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. In the second Ca site, Ca(2) is bonded to one O(10), one O(11), one O(12), one O(2), one O(4), one O(6), and one O(9) atom to form distorted CaO7 pentagonal bipyramids that share  a cornercorner with one Ca(5)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O7 pentagonal bipyramid,  an edgeedge with one Si(3)O4 tetrahedra,  a faceface with one Ca(5)O6 octahedra, and  a faceface with one Ca(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 75°. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(5), one O(7), one O(8), and one O(9) atom. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to one O(10), one O(3), one O(5), one O(6), and two equivalent O(4) atoms. In the fifth Ca site, Ca(5) is bonded to one O(11), one O(2), one O(3), one O(6), and two equivalent O(9) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(2)O7 pentagonal bipyramids,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and faces with two equivalent Ca(2)O7 pentagonal bipyramids. In the sixth Ca site, Ca(6) is bonded in a 5-coordinate geometry to one O(11), one O(5), one O(8), and two equivalent O(1) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share  a cornercorner with one Ca(5)O6 octahedra and corners with two equivalent Ca(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 65°. In the second Si site, Si(2) is bonded to one O(10), one O(8), and two equivalent O(9) atoms to form SiO4 tetrahedra that share corners with two equivalent Ca(5)O6 octahedra and corners with four equivalent Ca(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 49°. In the third Si site, Si(3) is bonded to one O(2), one O(7), and two equivalent O(4) atoms to form SiO4 tetrahedra that share  a cornercorner with one Ca(5)O6 octahedra and edges with two equivalent Ca(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 25°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Ca(3), one Ca(6), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ca(5), two equivalent Ca(2), and one Si(3) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(4), one Ca(5), two equivalent Ca(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), and one Si(3) atom. In the fifth O site, O(5) is bonded to one Ca(4), one Ca(6), two equivalent Ca(1), and two equivalent Ca(3) atoms to form a mixture of distorted corner and face-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles range from 7-24°. In the sixth O site, O(6) is bonded to one Ca(4), one Ca(5), two equivalent Ca(1), and two equivalent Ca(2) atoms to form a mixture of corner and face-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles range from 7-24°. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to two equivalent Ca(1), two equivalent Ca(3), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ca(6), two equivalent Ca(3), and one Si(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Ca(5), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(4), two equivalent Ca(2), and one Si(2) atom. In the eleventh O site, O(11) is bonded to one Ca(5), one Ca(6), two equivalent Ca(2), and two equivalent Ca(3) atoms to form face-sharing OCa6 octahedra. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to two equivalent Ca(2), two equivalent Ca(3), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.095
_cell_length_b   7.095
_cell_length_c   9.258
_cell_angle_alpha   68.088
_cell_angle_beta   68.088
_cell_angle_gamma   60.558
_symmetry_Int_Tables_number   1
_cell_volume   366.030
_cell_formula_units_Z   3
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  0.008  0.015  1.0
  Ca  Ca1  1  0.008  0.529  0.015  1.0
  Ca  Ca2  1  0.713  0.242  0.294  1.0
  Ca  Ca3  1  0.242  0.713  0.294  1.0
  Ca  Ca4  1  0.257  0.756  0.654  1.0
  Ca  Ca5  1  0.756  0.257  0.654  1.0
  Ca  Ca6  1  0.550  0.550  0.953  1.0
  Ca  Ca7  1  0.684  0.684  0.352  1.0
  Ca  Ca8  1  0.271  0.271  0.706  1.0
  Si  Si9  1  0.792  0.792  0.645  1.0
  Si  Si10  1  0.214  0.214  0.351  1.0
  Si  Si11  1  0.999  0.999  0.009  1.0
  O  O12  1  0.608  0.983  0.745  1.0
  O  O13  1  0.881  0.881  0.185  1.0
  O  O14  1  0.983  0.608  0.745  1.0
  O  O15  1  0.662  0.662  0.627  1.0
  O  O16  1  0.265  0.894  0.999  1.0
  O  O17  1  0.393  0.393  0.871  1.0
  O  O18  1  0.894  0.265  0.999  1.0
  O  O19  1  0.635  0.635  0.134  1.0
  O  O20  1  0.948  0.948  0.870  1.0
  O  O21  1  0.167  0.167  0.549  1.0
  O  O22  1  0.970  0.350  0.305  1.0
  O  O23  1  0.363  0.363  0.243  1.0
  O  O24  1  0.350  0.970  0.305  1.0
  O  O25  1  0.469  0.469  0.502  1.0
  O  O26  1  0.915  0.915  0.477  1.0
[/CIF]
.
The structure described by Ca3SiO5 crystallizes in the monoclinic Cm space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. In the second Ca site, Ca(2) is bonded to one O(10), one O(11), one O(12), one O(2), one O(4), one O(6), and one O(9) atom to form distorted CaO7 pentagonal bipyramids that share  a cornercorner with one Ca(5)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O7 pentagonal bipyramid,  an edgeedge with one Si(3)O4 tetrahedra,  a faceface with one Ca(5)O6 octahedra, and  a faceface with one Ca(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 75°. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(3), one O(5), one O(7), one O(8), and one O(9) atom. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to one O(10), one O(3), one O(5), one O(6), and two equivalent O(4) atoms. In the fifth Ca site, Ca(5) is bonded to one O(11), one O(2), one O(3), one O(6), and two equivalent O(9) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(2)O7 pentagonal bipyramids,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and faces with two equivalent Ca(2)O7 pentagonal bipyramids. In the sixth Ca site, Ca(6) is bonded in a 5-coordinate geometry to one O(11), one O(5), one O(8), and two equivalent O(1) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share  a cornercorner with one Ca(5)O6 octahedra and corners with two equivalent Ca(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 65°. In the second Si site, Si(2) is bonded to one O(10), one O(8), and two equivalent O(9) atoms to form SiO4 tetrahedra that share corners with two equivalent Ca(5)O6 octahedra and corners with four equivalent Ca(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 49°. In the third Si site, Si(3) is bonded to one O(2), one O(7), and two equivalent O(4) atoms to form SiO4 tetrahedra that share  a cornercorner with one Ca(5)O6 octahedra and edges with two equivalent Ca(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 25°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Ca(3), one Ca(6), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ca(5), two equivalent Ca(2), and one Si(3) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(4), one Ca(5), two equivalent Ca(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), and one Si(3) atom. In the fifth O site, O(5) is bonded to one Ca(4), one Ca(6), two equivalent Ca(1), and two equivalent Ca(3) atoms to form a mixture of distorted corner and face-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles range from 7-24°. In the sixth O site, O(6) is bonded to one Ca(4), one Ca(5), two equivalent Ca(1), and two equivalent Ca(2) atoms to form a mixture of corner and face-sharing OCa6 octahedra. The corner-sharing octahedral tilt angles range from 7-24°. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to two equivalent Ca(1), two equivalent Ca(3), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ca(6), two equivalent Ca(3), and one Si(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), one Ca(5), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(4), two equivalent Ca(2), and one Si(2) atom. In the eleventh O site, O(11) is bonded to one Ca(5), one Ca(6), two equivalent Ca(2), and two equivalent Ca(3) atoms to form face-sharing OCa6 octahedra. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to two equivalent Ca(2), two equivalent Ca(3), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.095
_cell_length_b   7.095
_cell_length_c   9.258
_cell_angle_alpha   68.088
_cell_angle_beta   68.088
_cell_angle_gamma   60.558
_symmetry_Int_Tables_number   1
_cell_volume   366.030
_cell_formula_units_Z   3
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  0.008  0.015  1.0
  Ca  Ca1  1  0.008  0.529  0.015  1.0
  Ca  Ca2  1  0.713  0.242  0.294  1.0
  Ca  Ca3  1  0.242  0.713  0.294  1.0
  Ca  Ca4  1  0.257  0.756  0.654  1.0
  Ca  Ca5  1  0.756  0.257  0.654  1.0
  Ca  Ca6  1  0.550  0.550  0.953  1.0
  Ca  Ca7  1  0.684  0.684  0.352  1.0
  Ca  Ca8  1  0.271  0.271  0.706  1.0
  Si  Si9  1  0.792  0.792  0.645  1.0
  Si  Si10  1  0.214  0.214  0.351  1.0
  Si  Si11  1  0.999  0.999  0.009  1.0
  O  O12  1  0.608  0.983  0.745  1.0
  O  O13  1  0.881  0.881  0.185  1.0
  O  O14  1  0.983  0.608  0.745  1.0
  O  O15  1  0.662  0.662  0.627  1.0
  O  O16  1  0.265  0.894  0.999  1.0
  O  O17  1  0.393  0.393  0.871  1.0
  O  O18  1  0.894  0.265  0.999  1.0
  O  O19  1  0.635  0.635  0.134  1.0
  O  O20  1  0.948  0.948  0.870  1.0
  O  O21  1  0.167  0.167  0.549  1.0
  O  O22  1  0.970  0.350  0.305  1.0
  O  O23  1  0.363  0.363  0.243  1.0
  O  O24  1  0.350  0.970  0.305  1.0
  O  O25  1  0.469  0.469  0.502  1.0
  O  O26  1  0.915  0.915  0.477  1.0
[/CIF]
.