The crystal structure described by Ca4Mn6Si5O28 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(11), one O(5), one O(9), two equivalent O(1), and two equivalent O(7) atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra, edges with four equivalent Mn(2)O6 octahedra,  an edgeedge with one Ca(1)O7 pentagonal bipyramid, and  an edgeedge with one Si(1)O4 tetrahedra. In the second Ca site, Ca(2) is bonded to one O(10), one O(12), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(3)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra,  an edgeedge with one Ca(2)O7 pentagonal bipyramid, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MnO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra,  an edgeedge with one Ca(1)O7 pentagonal bipyramid, and  an edgeedge with one Ca(2)O7 pentagonal bipyramid. In the second Mn site, Mn(2) is bonded to two equivalent O(11), two equivalent O(7), and two equivalent O(9) atoms to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Ca(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 14°. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(5), one O(9), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, corners with two equivalent Ca(1)O7 pentagonal bipyramids, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 48-58°. In the second Si site, Si(2) is bonded to one O(10), one O(6), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra, corners with two equivalent Ca(2)O7 pentagonal bipyramids,  a cornercorner with one Si(3)O4 tetrahedra, and  an edgeedge with one Ca(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 48-59°. In the third Si site, Si(3) is bonded to two equivalent O(10) and two equivalent O(8) atoms to form SiO4 tetrahedra that share corners with six equivalent Ca(2)O7 pentagonal bipyramids and corners with two equivalent Si(2)O4 tetrahedra. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Mn(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(2), one Mn(1), and one Si(2) atom. In the third O site, O(3) is bonded in a water-like geometry to two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Mn(1) atoms. In the fifth O site, O(5) is bonded to one Ca(1), two equivalent Mn(1), and one Si(1) atom to form distorted edge-sharing OCaMn2Si trigonal pyramids. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Mn(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a see-saw-like geometry to two equivalent Ca(1) and two equivalent Mn(2) atoms. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one Si(3) atom. In the ninth O site, O(9) is bonded to one Ca(1), two equivalent Mn(2), and one Si(1) atom to form distorted edge-sharing OCaMn2Si trigonal pyramids. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Ca(2), one Si(2), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1) and two equivalent Mn(2) atoms. In the twelfth O site, O(12) is bonded in a single-bond geometry to one Ca(2) atom. is represented by the CIF file [CIF]
data_Ca4Mn6Si5O28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.338
_cell_length_b   5.338
_cell_length_c   19.651
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   110.020
_symmetry_Int_Tables_number   1
_cell_volume   526.040
_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  0.693  0.307  0.101  1.0
  Ca  Ca1  1  0.304  0.696  0.413  1.0
  Ca  Ca2  1  0.693  0.307  0.899  1.0
  Ca  Ca3  1  0.304  0.696  0.587  1.0
  Mn  Mn4  1  0.497  1.000  0.251  1.0
  Mn  Mn5  1  0.000  0.503  0.251  1.0
  Mn  Mn6  1  0.497  1.000  0.749  1.0
  Mn  Mn7  1  0.000  0.503  0.749  1.0
  Mn  Mn8  1  0.685  0.793  0.000  1.0
  Mn  Mn9  1  0.207  0.315  0.000  1.0
  Si  Si10  1  0.028  0.972  0.152  1.0
  Si  Si11  1  0.966  0.034  0.349  1.0
  Si  Si12  1  0.028  0.972  0.848  1.0
  Si  Si13  1  0.966  0.034  0.651  1.0
  Si  Si14  1  0.898  0.102  0.500  1.0
  O  O15  1  0.342  0.094  0.169  1.0
  O  O16  1  0.095  0.351  0.333  1.0
  O  O17  1  0.342  0.094  0.831  1.0
  O  O18  1  0.095  0.351  0.667  1.0
  O  O19  1  0.649  0.905  0.333  1.0
  O  O20  1  0.906  0.658  0.169  1.0
  O  O21  1  0.649  0.905  0.667  1.0
  O  O22  1  0.906  0.658  0.831  1.0
  O  O23  1  0.362  0.638  0.222  1.0
  O  O24  1  0.636  0.364  0.279  1.0
  O  O25  1  0.362  0.638  0.778  1.0
  O  O26  1  0.636  0.364  0.721  1.0
  O  O27  1  0.867  0.133  0.198  1.0
  O  O28  1  0.131  0.869  0.306  1.0
  O  O29  1  0.867  0.133  0.802  1.0
  O  O30  1  0.131  0.869  0.694  1.0
  O  O31  1  0.507  0.079  0.000  1.0
  O  O32  1  0.041  0.426  0.500  1.0
  O  O33  1  0.574  0.959  0.500  1.0
  O  O34  1  0.921  0.493  0.000  1.0
  O  O35  1  0.966  0.034  0.070  1.0
  O  O36  1  0.016  0.984  0.431  1.0
  O  O37  1  0.966  0.034  0.930  1.0
  O  O38  1  0.016  0.984  0.569  1.0
  O  O39  1  0.443  0.557  0.061  1.0
  O  O40  1  0.583  0.417  0.430  1.0
  O  O41  1  0.443  0.557  0.939  1.0
  O  O42  1  0.583  0.417  0.570  1.0
[/CIF]
.
The crystal structure described by Ca4Mn6Si5O28 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(11), one O(5), one O(9), two equivalent O(1), and two equivalent O(7) atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra, edges with four equivalent Mn(2)O6 octahedra,  an edgeedge with one Ca(1)O7 pentagonal bipyramid, and  an edgeedge with one Si(1)O4 tetrahedra. In the second Ca site, Ca(2) is bonded to one O(10), one O(12), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(3)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra,  an edgeedge with one Ca(2)O7 pentagonal bipyramid, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MnO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Mn(1)O6 octahedra,  an edgeedge with one Ca(1)O7 pentagonal bipyramid, and  an edgeedge with one Ca(2)O7 pentagonal bipyramid. In the second Mn site, Mn(2) is bonded to two equivalent O(11), two equivalent O(7), and two equivalent O(9) atoms to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Ca(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 14°. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(5), one O(9), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, corners with two equivalent Ca(1)O7 pentagonal bipyramids, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 48-58°. In the second Si site, Si(2) is bonded to one O(10), one O(6), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra, corners with two equivalent Ca(2)O7 pentagonal bipyramids,  a cornercorner with one Si(3)O4 tetrahedra, and  an edgeedge with one Ca(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 48-59°. In the third Si site, Si(3) is bonded to two equivalent O(10) and two equivalent O(8) atoms to form SiO4 tetrahedra that share corners with six equivalent Ca(2)O7 pentagonal bipyramids and corners with two equivalent Si(2)O4 tetrahedra. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Mn(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(2), one Mn(1), and one Si(2) atom. In the third O site, O(3) is bonded in a water-like geometry to two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Mn(1) atoms. In the fifth O site, O(5) is bonded to one Ca(1), two equivalent Mn(1), and one Si(1) atom to form distorted edge-sharing OCaMn2Si trigonal pyramids. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Mn(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a see-saw-like geometry to two equivalent Ca(1) and two equivalent Mn(2) atoms. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one Si(3) atom. In the ninth O site, O(9) is bonded to one Ca(1), two equivalent Mn(2), and one Si(1) atom to form distorted edge-sharing OCaMn2Si trigonal pyramids. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Ca(2), one Si(2), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1) and two equivalent Mn(2) atoms. In the twelfth O site, O(12) is bonded in a single-bond geometry to one Ca(2) atom. is represented by the CIF file [CIF]
data_Ca4Mn6Si5O28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.338
_cell_length_b   5.338
_cell_length_c   19.651
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   110.020
_symmetry_Int_Tables_number   1
_cell_volume   526.040
_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  0.693  0.307  0.101  1.0
  Ca  Ca1  1  0.304  0.696  0.413  1.0
  Ca  Ca2  1  0.693  0.307  0.899  1.0
  Ca  Ca3  1  0.304  0.696  0.587  1.0
  Mn  Mn4  1  0.497  1.000  0.251  1.0
  Mn  Mn5  1  0.000  0.503  0.251  1.0
  Mn  Mn6  1  0.497  1.000  0.749  1.0
  Mn  Mn7  1  0.000  0.503  0.749  1.0
  Mn  Mn8  1  0.685  0.793  0.000  1.0
  Mn  Mn9  1  0.207  0.315  0.000  1.0
  Si  Si10  1  0.028  0.972  0.152  1.0
  Si  Si11  1  0.966  0.034  0.349  1.0
  Si  Si12  1  0.028  0.972  0.848  1.0
  Si  Si13  1  0.966  0.034  0.651  1.0
  Si  Si14  1  0.898  0.102  0.500  1.0
  O  O15  1  0.342  0.094  0.169  1.0
  O  O16  1  0.095  0.351  0.333  1.0
  O  O17  1  0.342  0.094  0.831  1.0
  O  O18  1  0.095  0.351  0.667  1.0
  O  O19  1  0.649  0.905  0.333  1.0
  O  O20  1  0.906  0.658  0.169  1.0
  O  O21  1  0.649  0.905  0.667  1.0
  O  O22  1  0.906  0.658  0.831  1.0
  O  O23  1  0.362  0.638  0.222  1.0
  O  O24  1  0.636  0.364  0.279  1.0
  O  O25  1  0.362  0.638  0.778  1.0
  O  O26  1  0.636  0.364  0.721  1.0
  O  O27  1  0.867  0.133  0.198  1.0
  O  O28  1  0.131  0.869  0.306  1.0
  O  O29  1  0.867  0.133  0.802  1.0
  O  O30  1  0.131  0.869  0.694  1.0
  O  O31  1  0.507  0.079  0.000  1.0
  O  O32  1  0.041  0.426  0.500  1.0
  O  O33  1  0.574  0.959  0.500  1.0
  O  O34  1  0.921  0.493  0.000  1.0
  O  O35  1  0.966  0.034  0.070  1.0
  O  O36  1  0.016  0.984  0.431  1.0
  O  O37  1  0.966  0.034  0.930  1.0
  O  O38  1  0.016  0.984  0.569  1.0
  O  O39  1  0.443  0.557  0.061  1.0
  O  O40  1  0.583  0.417  0.430  1.0
  O  O41  1  0.443  0.557  0.939  1.0
  O  O42  1  0.583  0.417  0.570  1.0
[/CIF]
.