The crystal structure described by CaMn7O8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Mn(3)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Ca(1)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Mn(4)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the third Mn site, Mn(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the fourth Mn site, Mn(4) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Mn(2), two equivalent Mn(1), and two equivalent Mn(3) atoms to form OCaMn5 octahedra that share corners with three equivalent O(1)CaMn5 octahedra, corners with three equivalent O(3)Mn6 octahedra,  an edgeedge with one O(1)CaMn5 octahedra, edges with three equivalent O(3)Mn6 octahedra, and edges with eight equivalent O(2)CaMn5 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to one Ca(1), one Mn(1), one Mn(3), one Mn(4), and two equivalent Mn(2) atoms to form OCaMn5 octahedra that share corners with six equivalent O(2)CaMn5 octahedra, edges with four equivalent O(1)CaMn5 octahedra, edges with four equivalent O(2)CaMn5 octahedra, and edges with four equivalent O(3)Mn6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(3) is bonded to one Mn(2), one Mn(4), two equivalent Mn(1), and two equivalent Mn(3) atoms to form OMn6 octahedra that share corners with three equivalent O(1)CaMn5 octahedra, corners with three equivalent O(3)Mn6 octahedra,  an edgeedge with one O(3)Mn6 octahedra, edges with three equivalent O(1)CaMn5 octahedra, and edges with eight equivalent O(2)CaMn5 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. is represented by the CIF file [CIF]
data_CaMn7O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.431
_cell_length_b   6.431
_cell_length_c   5.567
_cell_angle_alpha   73.065
_cell_angle_beta   73.065
_cell_angle_gamma   59.924
_symmetry_Int_Tables_number   1
_cell_volume   187.646
_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  0.500  0.500  0.500  1.0
  Mn  Mn1  1  0.753  0.247  0.000  1.0
  Mn  Mn2  1  0.751  0.751  0.998  1.0
  Mn  Mn3  1  0.249  0.249  0.002  1.0
  Mn  Mn4  1  0.000  0.500  0.500  1.0
  Mn  Mn5  1  0.500  0.000  0.500  1.0
  Mn  Mn6  1  0.247  0.753  0.000  1.0
  Mn  Mn7  1  0.000  0.000  0.500  1.0
  O  O8  1  0.373  0.373  0.242  1.0
  O  O9  1  0.884  0.370  0.245  1.0
  O  O10  1  0.370  0.884  0.245  1.0
  O  O11  1  0.875  0.875  0.254  1.0
  O  O12  1  0.627  0.627  0.758  1.0
  O  O13  1  0.630  0.116  0.755  1.0
  O  O14  1  0.116  0.630  0.755  1.0
  O  O15  1  0.125  0.125  0.746  1.0
[/CIF]
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The crystal structure described by CaMn7O8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Mn(3)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Ca(1)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Mn(4)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the third Mn site, Mn(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with six equivalent Mn(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-3°. In the fourth Mn site, Mn(4) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Mn(2)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Mn(2), two equivalent Mn(1), and two equivalent Mn(3) atoms to form OCaMn5 octahedra that share corners with three equivalent O(1)CaMn5 octahedra, corners with three equivalent O(3)Mn6 octahedra,  an edgeedge with one O(1)CaMn5 octahedra, edges with three equivalent O(3)Mn6 octahedra, and edges with eight equivalent O(2)CaMn5 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second O site, O(2) is bonded to one Ca(1), one Mn(1), one Mn(3), one Mn(4), and two equivalent Mn(2) atoms to form OCaMn5 octahedra that share corners with six equivalent O(2)CaMn5 octahedra, edges with four equivalent O(1)CaMn5 octahedra, edges with four equivalent O(2)CaMn5 octahedra, and edges with four equivalent O(3)Mn6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third O site, O(3) is bonded to one Mn(2), one Mn(4), two equivalent Mn(1), and two equivalent Mn(3) atoms to form OMn6 octahedra that share corners with three equivalent O(1)CaMn5 octahedra, corners with three equivalent O(3)Mn6 octahedra,  an edgeedge with one O(3)Mn6 octahedra, edges with three equivalent O(1)CaMn5 octahedra, and edges with eight equivalent O(2)CaMn5 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. is represented by the CIF file [CIF]
data_CaMn7O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.431
_cell_length_b   6.431
_cell_length_c   5.567
_cell_angle_alpha   73.065
_cell_angle_beta   73.065
_cell_angle_gamma   59.924
_symmetry_Int_Tables_number   1
_cell_volume   187.646
_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  0.500  0.500  0.500  1.0
  Mn  Mn1  1  0.753  0.247  0.000  1.0
  Mn  Mn2  1  0.751  0.751  0.998  1.0
  Mn  Mn3  1  0.249  0.249  0.002  1.0
  Mn  Mn4  1  0.000  0.500  0.500  1.0
  Mn  Mn5  1  0.500  0.000  0.500  1.0
  Mn  Mn6  1  0.247  0.753  0.000  1.0
  Mn  Mn7  1  0.000  0.000  0.500  1.0
  O  O8  1  0.373  0.373  0.242  1.0
  O  O9  1  0.884  0.370  0.245  1.0
  O  O10  1  0.370  0.884  0.245  1.0
  O  O11  1  0.875  0.875  0.254  1.0
  O  O12  1  0.627  0.627  0.758  1.0
  O  O13  1  0.630  0.116  0.755  1.0
  O  O14  1  0.116  0.630  0.755  1.0
  O  O15  1  0.125  0.125  0.746  1.0
[/CIF]
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