The material structure described by MgNb4Mn6O18 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(13), one O(16), one O(17), one O(3), one O(4), and one O(9) atom to form distorted MgO6 octahedra that share corners with three equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(6)O6 octahedra, corners with three equivalent Nb(2)O6 pentagonal pyramids, edges with three equivalent Nb(4)O6 octahedra, and  a faceface with one Mn(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-67°. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(11), one O(14), one O(18), one O(2), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(5)O6 octahedra, and  a faceface with one Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-54°. In the second Nb site, Nb(2) is bonded to one O(1), one O(13), one O(15), one O(3), one O(4), and one O(5) atom to form distorted NbO6 pentagonal pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(5)O6 octahedra, edges with three equivalent Mn(6)O6 octahedra, and  a faceface with one Nb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. In the third Nb site, Nb(3) is bonded to one O(10), one O(11), one O(12), one O(18), one O(6), and one O(7) atom to form distorted NbO6 octahedra that share corners with three equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and  a faceface with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-62°. In the fourth Nb site, Nb(4) is bonded to one O(13), one O(16), one O(17), one O(3), one O(4), and one O(9) atom to form distorted NbO6 octahedra that share corners with three equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra, corners with three equivalent Mn(6)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Nb(2)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 44-60°. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(10), one O(11), one O(12), one O(18), one O(6), and one O(7) atom to form distorted MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra, edges with three equivalent Nb(3)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-53°. In the second Mn site, Mn(2) is bonded to one O(1), one O(14), one O(15), one O(2), one O(5), and one O(8) atom to form distorted MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Nb(2)O6 pentagonal pyramids, edges with three equivalent Mn(5)O6 octahedra, and  a faceface with one Mn(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-54°. In the third Mn site, Mn(3) is bonded to one O(10), one O(12), one O(16), one O(17), one O(6), and one O(9) atom to form distorted MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Nb(3)O6 octahedra, corners with three equivalent Nb(4)O6 octahedra, edges with three equivalent Mn(4)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-60°. In the fourth Mn site, Mn(4) is bonded to one O(10), one O(12), one O(16), one O(17), one O(6), and one O(9) atom to form MnO6 octahedra that share corners with three equivalent Nb(3)O6 octahedra, corners with three equivalent Nb(4)O6 octahedra, corners with three equivalent Mn(1)O6 octahedra, edges with three equivalent Mn(3)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-62°. In the fifth Mn site, Mn(5) is bonded to one O(1), one O(14), one O(15), one O(2), one O(5), and one O(8) atom to form MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(6)O6 octahedra, corners with three equivalent Nb(2)O6 pentagonal pyramids, and edges with three equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-49°. In the sixth Mn site, Mn(6) is bonded to one O(1), one O(13), one O(15), one O(3), one O(4), and one O(5) atom to form distorted MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Nb(4)O6 octahedra, corners with three equivalent Mn(5)O6 octahedra, edges with three equivalent Nb(2)O6 pentagonal pyramids, and  a faceface with one Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-67°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded to one Nb(2), one Mn(2), one Mn(5), and one Mn(6) atom to form distorted OMn3Nb trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(4)MgMnNb2 trigonal pyramid,  an edgeedge with one O(15)Mn3Nb trigonal pyramid, and  an edgeedge with one O(5)Mn3Nb trigonal pyramid. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(5) atom. In the third O site, O(3) is bonded to one Mg(1), one Nb(2), one Nb(4), and one Mn(6) atom to form distorted OMgMnNb2 trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(13)MgMnNb2 trigonal pyramid,  an edgeedge with one O(4)MgMnNb2 trigonal pyramid, and  an edgeedge with one O(15)Mn3Nb trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Nb(2), one Nb(4), and one Mn(6) atom to form distorted OMgMnNb2 trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(13)MgMnNb2 trigonal pyramid,  an edgeedge with one O(3)MgMnNb2 trigonal pyramid, and  an edgeedge with one O(1)Mn3Nb trigonal pyramid. In the fifth O site, O(5) is bonded to one Nb(2), one Mn(2), one Mn(5), and one Mn(6) atom to form distorted OMn3Nb trigonal pyramids that share corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids,  an edgeedge with one O(13)MgMnNb2 trigonal pyramid,  an edgeedge with one O(1)Mn3Nb trigonal pyramid, and  an edgeedge with one O(15)Mn3Nb trigonal pyramid. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Nb(3), one Mn(1), one Mn(3), and one Mn(4) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Mn(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(5) atom. In the ninth O site, O(9) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nb(4), one Mn(3), and one Mn(4) atom. In the tenth O site, O(10) is bonded to one Nb(3), one Mn(1), one Mn(3), and one Mn(4) atom to form a mixture of distorted corner and edge-sharing OMn3Nb trigonal pyramids. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Mn(1) atom. In the twelfth O site, O(12) is bonded to one Nb(3), one Mn(1), one Mn(3), and one Mn(4) atom to form a mixture of distorted corner and edge-sharing OMn3Nb trigonal pyramids. In the thirteenth O site, O(13) is bonded to one Mg(1), one Nb(2), one Nb(4), and one Mn(6) atom to form distorted OMgMnNb2 trigonal pyramids that share corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids,  an edgeedge with one O(3)MgMnNb2 trigonal pyramid,  an edgeedge with one O(4)MgMnNb2 trigonal pyramid, and  an edgeedge with one O(5)Mn3Nb trigonal pyramid. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(5) atom. In the fifteenth O site, O(15) is bonded to one Nb(2), one Mn(2), one Mn(5), and one Mn(6) atom to form distorted OMn3Nb trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(3)MgMnNb2 trigonal pyramid,  an edgeedge with one O(1)Mn3Nb trigonal pyramid, and  an edgeedge with one O(5)Mn3Nb trigonal pyramid. In the sixteenth O site, O(16) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nb(4), one Mn(3), and one Mn(4) atom. In the seventeenth O site, O(17) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nb(4), one Mn(3), and one Mn(4) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Mn(1) atom. is represented by the CIF file [CIF]
data_MgMn6Nb4O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.325
_cell_length_b   5.326
_cell_length_c   14.523
_cell_angle_alpha   90.319
_cell_angle_beta   89.964
_cell_angle_gamma   120.264
_symmetry_Int_Tables_number   1
_cell_volume   355.800
_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
  Mg  Mg0  1  0.333  0.668  0.308  1.0
  Mn  Mn1  1  0.661  0.329  0.684  1.0
  Mn  Mn2  1  0.665  0.332  0.982  1.0
  Mn  Mn3  1  0.667  0.335  0.475  1.0
  Mn  Mn4  1  0.333  0.668  0.519  1.0
  Mn  Mn5  1  0.333  0.666  0.004  1.0
  Mn  Mn6  1  0.666  0.332  0.195  1.0
  Nb  Nb7  1  0.998  0.997  0.859  1.0
  Nb  Nb8  1  0.999  1.000  0.141  1.0
  Nb  Nb9  1  0.997  0.000  0.647  1.0
  Nb  Nb10  1  0.999  0.999  0.354  1.0
  O  O11  1  0.339  0.316  0.086  1.0
  O  O12  1  0.679  0.692  0.920  1.0
  O  O13  1  0.012  0.290  0.251  1.0
  O  O14  1  0.278  0.988  0.251  1.0
  O  O15  1  0.976  0.659  0.086  1.0
  O  O16  1  0.688  0.653  0.583  1.0
  O  O17  1  0.764  0.064  0.745  1.0
  O  O18  1  0.014  0.319  0.921  1.0
  O  O19  1  0.039  0.693  0.412  1.0
  O  O20  1  0.360  0.043  0.589  1.0
  O  O21  1  0.312  0.243  0.745  1.0
  O  O22  1  0.961  0.319  0.588  1.0
  O  O23  1  0.707  0.720  0.251  1.0
  O  O24  1  0.306  0.984  0.920  1.0
  O  O25  1  0.682  0.021  0.086  1.0
  O  O26  1  0.654  0.964  0.412  1.0
  O  O27  1  0.308  0.346  0.413  1.0
  O  O28  1  0.929  0.688  0.743  1.0
[/CIF]
.
The material structure described by MgNb4Mn6O18 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(13), one O(16), one O(17), one O(3), one O(4), and one O(9) atom to form distorted MgO6 octahedra that share corners with three equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(6)O6 octahedra, corners with three equivalent Nb(2)O6 pentagonal pyramids, edges with three equivalent Nb(4)O6 octahedra, and  a faceface with one Mn(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-67°. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(11), one O(14), one O(18), one O(2), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(5)O6 octahedra, and  a faceface with one Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-54°. In the second Nb site, Nb(2) is bonded to one O(1), one O(13), one O(15), one O(3), one O(4), and one O(5) atom to form distorted NbO6 pentagonal pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(5)O6 octahedra, edges with three equivalent Mn(6)O6 octahedra, and  a faceface with one Nb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. In the third Nb site, Nb(3) is bonded to one O(10), one O(11), one O(12), one O(18), one O(6), and one O(7) atom to form distorted NbO6 octahedra that share corners with three equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and  a faceface with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-62°. In the fourth Nb site, Nb(4) is bonded to one O(13), one O(16), one O(17), one O(3), one O(4), and one O(9) atom to form distorted NbO6 octahedra that share corners with three equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra, corners with three equivalent Mn(6)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Nb(2)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 44-60°. There are six inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(10), one O(11), one O(12), one O(18), one O(6), and one O(7) atom to form distorted MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(4)O6 octahedra, edges with three equivalent Nb(3)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-53°. In the second Mn site, Mn(2) is bonded to one O(1), one O(14), one O(15), one O(2), one O(5), and one O(8) atom to form distorted MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Nb(2)O6 pentagonal pyramids, edges with three equivalent Mn(5)O6 octahedra, and  a faceface with one Mn(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-54°. In the third Mn site, Mn(3) is bonded to one O(10), one O(12), one O(16), one O(17), one O(6), and one O(9) atom to form distorted MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Nb(3)O6 octahedra, corners with three equivalent Nb(4)O6 octahedra, edges with three equivalent Mn(4)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-60°. In the fourth Mn site, Mn(4) is bonded to one O(10), one O(12), one O(16), one O(17), one O(6), and one O(9) atom to form MnO6 octahedra that share corners with three equivalent Nb(3)O6 octahedra, corners with three equivalent Nb(4)O6 octahedra, corners with three equivalent Mn(1)O6 octahedra, edges with three equivalent Mn(3)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-62°. In the fifth Mn site, Mn(5) is bonded to one O(1), one O(14), one O(15), one O(2), one O(5), and one O(8) atom to form MnO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Mn(6)O6 octahedra, corners with three equivalent Nb(2)O6 pentagonal pyramids, and edges with three equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-49°. In the sixth Mn site, Mn(6) is bonded to one O(1), one O(13), one O(15), one O(3), one O(4), and one O(5) atom to form distorted MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Nb(4)O6 octahedra, corners with three equivalent Mn(5)O6 octahedra, edges with three equivalent Nb(2)O6 pentagonal pyramids, and  a faceface with one Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-67°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded to one Nb(2), one Mn(2), one Mn(5), and one Mn(6) atom to form distorted OMn3Nb trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(4)MgMnNb2 trigonal pyramid,  an edgeedge with one O(15)Mn3Nb trigonal pyramid, and  an edgeedge with one O(5)Mn3Nb trigonal pyramid. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(5) atom. In the third O site, O(3) is bonded to one Mg(1), one Nb(2), one Nb(4), and one Mn(6) atom to form distorted OMgMnNb2 trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(13)MgMnNb2 trigonal pyramid,  an edgeedge with one O(4)MgMnNb2 trigonal pyramid, and  an edgeedge with one O(15)Mn3Nb trigonal pyramid. In the fourth O site, O(4) is bonded to one Mg(1), one Nb(2), one Nb(4), and one Mn(6) atom to form distorted OMgMnNb2 trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(13)MgMnNb2 trigonal pyramid,  an edgeedge with one O(3)MgMnNb2 trigonal pyramid, and  an edgeedge with one O(1)Mn3Nb trigonal pyramid. In the fifth O site, O(5) is bonded to one Nb(2), one Mn(2), one Mn(5), and one Mn(6) atom to form distorted OMn3Nb trigonal pyramids that share corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids,  an edgeedge with one O(13)MgMnNb2 trigonal pyramid,  an edgeedge with one O(1)Mn3Nb trigonal pyramid, and  an edgeedge with one O(15)Mn3Nb trigonal pyramid. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Nb(3), one Mn(1), one Mn(3), and one Mn(4) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Mn(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(5) atom. In the ninth O site, O(9) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nb(4), one Mn(3), and one Mn(4) atom. In the tenth O site, O(10) is bonded to one Nb(3), one Mn(1), one Mn(3), and one Mn(4) atom to form a mixture of distorted corner and edge-sharing OMn3Nb trigonal pyramids. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Mn(1) atom. In the twelfth O site, O(12) is bonded to one Nb(3), one Mn(1), one Mn(3), and one Mn(4) atom to form a mixture of distorted corner and edge-sharing OMn3Nb trigonal pyramids. In the thirteenth O site, O(13) is bonded to one Mg(1), one Nb(2), one Nb(4), and one Mn(6) atom to form distorted OMgMnNb2 trigonal pyramids that share corners with two equivalent O(3)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(15)Mn3Nb trigonal pyramids,  an edgeedge with one O(3)MgMnNb2 trigonal pyramid,  an edgeedge with one O(4)MgMnNb2 trigonal pyramid, and  an edgeedge with one O(5)Mn3Nb trigonal pyramid. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Nb(1), one Mn(2), and one Mn(5) atom. In the fifteenth O site, O(15) is bonded to one Nb(2), one Mn(2), one Mn(5), and one Mn(6) atom to form distorted OMn3Nb trigonal pyramids that share corners with two equivalent O(13)MgMnNb2 trigonal pyramids, corners with two equivalent O(4)MgMnNb2 trigonal pyramids, corners with two equivalent O(1)Mn3Nb trigonal pyramids, corners with two equivalent O(5)Mn3Nb trigonal pyramids,  an edgeedge with one O(3)MgMnNb2 trigonal pyramid,  an edgeedge with one O(1)Mn3Nb trigonal pyramid, and  an edgeedge with one O(5)Mn3Nb trigonal pyramid. In the sixteenth O site, O(16) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nb(4), one Mn(3), and one Mn(4) atom. In the seventeenth O site, O(17) is bonded in a distorted see-saw-like geometry to one Mg(1), one Nb(4), one Mn(3), and one Mn(4) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Mn(1) atom. is represented by the CIF file [CIF]
data_MgMn6Nb4O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.325
_cell_length_b   5.326
_cell_length_c   14.523
_cell_angle_alpha   90.319
_cell_angle_beta   89.964
_cell_angle_gamma   120.264
_symmetry_Int_Tables_number   1
_cell_volume   355.800
_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
  Mg  Mg0  1  0.333  0.668  0.308  1.0
  Mn  Mn1  1  0.661  0.329  0.684  1.0
  Mn  Mn2  1  0.665  0.332  0.982  1.0
  Mn  Mn3  1  0.667  0.335  0.475  1.0
  Mn  Mn4  1  0.333  0.668  0.519  1.0
  Mn  Mn5  1  0.333  0.666  0.004  1.0
  Mn  Mn6  1  0.666  0.332  0.195  1.0
  Nb  Nb7  1  0.998  0.997  0.859  1.0
  Nb  Nb8  1  0.999  1.000  0.141  1.0
  Nb  Nb9  1  0.997  0.000  0.647  1.0
  Nb  Nb10  1  0.999  0.999  0.354  1.0
  O  O11  1  0.339  0.316  0.086  1.0
  O  O12  1  0.679  0.692  0.920  1.0
  O  O13  1  0.012  0.290  0.251  1.0
  O  O14  1  0.278  0.988  0.251  1.0
  O  O15  1  0.976  0.659  0.086  1.0
  O  O16  1  0.688  0.653  0.583  1.0
  O  O17  1  0.764  0.064  0.745  1.0
  O  O18  1  0.014  0.319  0.921  1.0
  O  O19  1  0.039  0.693  0.412  1.0
  O  O20  1  0.360  0.043  0.589  1.0
  O  O21  1  0.312  0.243  0.745  1.0
  O  O22  1  0.961  0.319  0.588  1.0
  O  O23  1  0.707  0.720  0.251  1.0
  O  O24  1  0.306  0.984  0.920  1.0
  O  O25  1  0.682  0.021  0.086  1.0
  O  O26  1  0.654  0.964  0.412  1.0
  O  O27  1  0.308  0.346  0.413  1.0
  O  O28  1  0.929  0.688  0.743  1.0
[/CIF]
.