The compound described by Ca10(PO4)6O crystallizes in the hexagonal P-6 space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(4), and three equivalent O(6) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(3) atoms. In the third Ca site, Ca(3) is bonded to one O(1), one O(3), two equivalent O(5), and two equivalent O(6) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to one O(4), one O(7), two equivalent O(5), and two equivalent O(6) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with two equivalent Ca(3)O6 pentagonal pyramids and  an edgeedge with one Ca(3)O6 pentagonal pyramid. In the second P site, P(2) is bonded to one O(2), one O(4), and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Ca(3)O6 pentagonal pyramids. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Ca(4), and one P(2) atom. In the second O site, O(7) is bonded in a trigonal planar geometry to three equivalent Ca(4) atoms. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one P(2) atom. In the fifth O site, O(3) is bonded to one Ca(3), two equivalent Ca(2), and one P(1) atom to form distorted edge-sharing OCa3P tetrahedra. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(4), two equivalent Ca(1), and one P(2) atom. In the seventh O site, O(5) is bonded in a 1-coordinate geometry to one Ca(3), one Ca(4), and one P(1) atom. is represented by the CIF file [CIF]
data_Ca10P6O25
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.595
_cell_length_b   9.595
_cell_length_c   6.901
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   550.187
_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  0.333  0.667  0.746  1.0
  Ca  Ca1  1  0.667  0.333  0.744  1.0
  Ca  Ca2  1  0.333  0.667  0.254  1.0
  Ca  Ca3  1  0.275  0.996  0.000  1.0
  Ca  Ca4  1  0.720  0.725  0.000  1.0
  Ca  Ca5  1  0.004  0.280  0.000  1.0
  Ca  Ca6  1  0.770  0.992  0.500  1.0
  Ca  Ca7  1  0.222  0.230  0.500  1.0
  Ca  Ca8  1  0.008  0.778  0.500  1.0
  Ca  Ca9  1  0.667  0.333  0.256  1.0
  P  P10  1  0.971  0.616  0.000  1.0
  P  P11  1  0.645  0.029  0.000  1.0
  P  P12  1  0.588  0.618  0.500  1.0
  P  P13  1  0.031  0.412  0.500  1.0
  P  P14  1  0.382  0.969  0.500  1.0
  P  P15  1  0.384  0.355  0.000  1.0
  O  O16  1  0.325  0.479  0.000  1.0
  O  O17  1  0.154  0.675  0.000  1.0
  O  O18  1  0.521  0.846  0.000  1.0
  O  O19  1  0.655  0.502  0.500  1.0
  O  O20  1  0.847  0.345  0.500  1.0
  O  O21  1  0.498  0.153  0.500  1.0
  O  O22  1  0.574  0.448  0.000  1.0
  O  O23  1  0.874  0.426  0.000  1.0
  O  O24  1  0.552  0.126  0.000  1.0
  O  O25  1  0.400  0.526  0.500  1.0
  O  O26  1  0.126  0.600  0.500  1.0
  O  O27  1  0.474  0.874  0.500  1.0
  O  O28  1  0.324  0.242  0.821  1.0
  O  O29  1  0.918  0.676  0.179  1.0
  O  O30  1  0.758  0.082  0.179  1.0
  O  O31  1  0.758  0.082  0.821  1.0
  O  O32  1  0.918  0.676  0.821  1.0
  O  O33  1  0.324  0.242  0.179  1.0
  O  O34  1  0.644  0.728  0.683  1.0
  O  O35  1  0.084  0.356  0.317  1.0
  O  O36  1  0.272  0.916  0.317  1.0
  O  O37  1  0.272  0.916  0.683  1.0
  O  O38  1  0.084  0.356  0.683  1.0
  O  O39  1  0.644  0.728  0.317  1.0
  O  O40  1  0.000  0.000  0.500  1.0
[/CIF]
.
The compound described by Ca10(PO4)6O crystallizes in the hexagonal P-6 space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(4), and three equivalent O(6) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to three equivalent O(2) and three equivalent O(3) atoms. In the third Ca site, Ca(3) is bonded to one O(1), one O(3), two equivalent O(5), and two equivalent O(6) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to one O(4), one O(7), two equivalent O(5), and two equivalent O(6) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), and two equivalent O(5) atoms to form PO4 tetrahedra that share corners with two equivalent Ca(3)O6 pentagonal pyramids and  an edgeedge with one Ca(3)O6 pentagonal pyramid. In the second P site, P(2) is bonded to one O(2), one O(4), and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Ca(3)O6 pentagonal pyramids. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(3), one Ca(4), and one P(2) atom. In the second O site, O(7) is bonded in a trigonal planar geometry to three equivalent Ca(4) atoms. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one P(2) atom. In the fifth O site, O(3) is bonded to one Ca(3), two equivalent Ca(2), and one P(1) atom to form distorted edge-sharing OCa3P tetrahedra. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(4), two equivalent Ca(1), and one P(2) atom. In the seventh O site, O(5) is bonded in a 1-coordinate geometry to one Ca(3), one Ca(4), and one P(1) atom. is represented by the CIF file [CIF]
data_Ca10P6O25
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.595
_cell_length_b   9.595
_cell_length_c   6.901
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   550.187
_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  0.333  0.667  0.746  1.0
  Ca  Ca1  1  0.667  0.333  0.744  1.0
  Ca  Ca2  1  0.333  0.667  0.254  1.0
  Ca  Ca3  1  0.275  0.996  0.000  1.0
  Ca  Ca4  1  0.720  0.725  0.000  1.0
  Ca  Ca5  1  0.004  0.280  0.000  1.0
  Ca  Ca6  1  0.770  0.992  0.500  1.0
  Ca  Ca7  1  0.222  0.230  0.500  1.0
  Ca  Ca8  1  0.008  0.778  0.500  1.0
  Ca  Ca9  1  0.667  0.333  0.256  1.0
  P  P10  1  0.971  0.616  0.000  1.0
  P  P11  1  0.645  0.029  0.000  1.0
  P  P12  1  0.588  0.618  0.500  1.0
  P  P13  1  0.031  0.412  0.500  1.0
  P  P14  1  0.382  0.969  0.500  1.0
  P  P15  1  0.384  0.355  0.000  1.0
  O  O16  1  0.325  0.479  0.000  1.0
  O  O17  1  0.154  0.675  0.000  1.0
  O  O18  1  0.521  0.846  0.000  1.0
  O  O19  1  0.655  0.502  0.500  1.0
  O  O20  1  0.847  0.345  0.500  1.0
  O  O21  1  0.498  0.153  0.500  1.0
  O  O22  1  0.574  0.448  0.000  1.0
  O  O23  1  0.874  0.426  0.000  1.0
  O  O24  1  0.552  0.126  0.000  1.0
  O  O25  1  0.400  0.526  0.500  1.0
  O  O26  1  0.126  0.600  0.500  1.0
  O  O27  1  0.474  0.874  0.500  1.0
  O  O28  1  0.324  0.242  0.821  1.0
  O  O29  1  0.918  0.676  0.179  1.0
  O  O30  1  0.758  0.082  0.179  1.0
  O  O31  1  0.758  0.082  0.821  1.0
  O  O32  1  0.918  0.676  0.821  1.0
  O  O33  1  0.324  0.242  0.179  1.0
  O  O34  1  0.644  0.728  0.683  1.0
  O  O35  1  0.084  0.356  0.317  1.0
  O  O36  1  0.272  0.916  0.317  1.0
  O  O37  1  0.272  0.916  0.683  1.0
  O  O38  1  0.084  0.356  0.683  1.0
  O  O39  1  0.644  0.728  0.317  1.0
  O  O40  1  0.000  0.000  0.500  1.0
[/CIF]
.