The crystal structure described by MgU7Zr3O20 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(12), one O(14), one O(3), two equivalent O(11), and two equivalent O(17) atoms. There are seven inequivalent U sites. In the first U site, U(1) is bonded in a body-centered cubic geometry to one O(1), one O(6), one O(7), one O(9), two equivalent O(13), and two equivalent O(5) atoms. In the second U site, U(2) is bonded in a 7-coordinate geometry to one O(3), one O(7), one O(9), two equivalent O(11), and two equivalent O(4) atoms. In the third U site, U(3) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(14), one O(3), two equivalent O(17), and two equivalent O(8) atoms. In the fourth U site, U(4) is bonded in a 7-coordinate geometry to one O(11), one O(13), one O(4), two equivalent O(3), and two equivalent O(9) atoms. In the fifth U site, U(5) is bonded in a body-centered cubic geometry to one O(16), one O(18), one O(19), one O(8), two equivalent O(10), and two equivalent O(15) atoms. In the sixth U site, U(6) is bonded in a body-centered cubic geometry to one O(10), one O(14), one O(15), one O(20), two equivalent O(16), and two equivalent O(19) atoms. In the seventh U site, U(7) is bonded in a body-centered cubic geometry to one O(1), one O(18), one O(19), one O(6), two equivalent O(2), and two equivalent O(20) atoms. There are three inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a body-centered cubic geometry to one O(13), one O(2), one O(4), one O(5), two equivalent O(1), and two equivalent O(7) atoms. In the second Zr site, Zr(2) is bonded in a 7-coordinate geometry to one O(16), one O(17), one O(8), two equivalent O(12), and two equivalent O(14) atoms. In the third Zr site, Zr(3) is bonded in a body-centered cubic geometry to one O(15), one O(2), one O(20), one O(5), two equivalent O(18), and two equivalent O(6) atoms. There are twenty inequivalent O sites. In the first O site, O(1) is bonded to one U(1), one U(7), and two equivalent Zr(1) atoms to form OZr2U2 tetrahedra that share  a cornercorner with one O(19)U4 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra,  a cornercorner with one O(18)Zr2U2 tetrahedra, corners with two equivalent O(1)Zr2U2 tetrahedra, corners with two equivalent O(20)ZrU3 tetrahedra, corners with two equivalent O(4)ZrU3 tetrahedra, corners with three equivalent O(7)Zr2U2 tetrahedra, corners with four equivalent O(5)Zr2U2 tetrahedra,  an edgeedge with one O(6)Zr2U2 tetrahedra,  an edgeedge with one O(7)Zr2U2 tetrahedra, edges with two equivalent O(2)Zr2U2 tetrahedra, and edges with two equivalent O(13)ZrU3 tetrahedra. In the second O site, O(2) is bonded to two equivalent U(7), one Zr(1), and one Zr(3) atom to form OZr2U2 tetrahedra that share  a cornercorner with one O(13)ZrU3 tetrahedra,  a cornercorner with one O(15)ZrU3 tetrahedra,  a cornercorner with one O(4)ZrU3 tetrahedra, corners with two equivalent O(19)U4 tetrahedra, corners with two equivalent O(2)Zr2U2 tetrahedra, corners with two equivalent O(7)Zr2U2 tetrahedra, corners with three equivalent O(20)ZrU3 tetrahedra, corners with four equivalent O(6)Zr2U2 tetrahedra,  an edgeedge with one O(5)Zr2U2 tetrahedra,  an edgeedge with one O(20)ZrU3 tetrahedra, edges with two equivalent O(1)Zr2U2 tetrahedra, and edges with two equivalent O(18)Zr2U2 tetrahedra. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(1), one U(2), one U(3), and two equivalent U(4) atoms. In the fourth O site, O(4) is bonded to one U(4), two equivalent U(2), and one Zr(1) atom to form OZrU3 tetrahedra that share corners with three equivalent O(11)Mg2U3 square pyramids,  a cornercorner with one O(2)Zr2U2 tetrahedra,  a cornercorner with one O(5)Zr2U2 tetrahedra, corners with two equivalent O(1)Zr2U2 tetrahedra, corners with two equivalent O(4)ZrU3 tetrahedra, corners with four equivalent O(9)U4 tetrahedra,  an edgeedge with one O(11)Mg2U3 square pyramid,  an edgeedge with one O(13)ZrU3 tetrahedra, and edges with two equivalent O(7)Zr2U2 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent U(1), one Zr(1), and one Zr(3) atom to form OZr2U2 tetrahedra that share  a cornercorner with one O(15)ZrU3 tetrahedra,  a cornercorner with one O(20)ZrU3 tetrahedra,  a cornercorner with one O(4)ZrU3 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with two equivalent O(18)Zr2U2 tetrahedra, corners with two equivalent O(5)Zr2U2 tetrahedra, corners with three equivalent O(13)ZrU3 tetrahedra, corners with four equivalent O(1)Zr2U2 tetrahedra,  an edgeedge with one O(2)Zr2U2 tetrahedra,  an edgeedge with one O(13)ZrU3 tetrahedra, edges with two equivalent O(6)Zr2U2 tetrahedra, and edges with two equivalent O(7)Zr2U2 tetrahedra. In the sixth O site, O(6) is bonded to one U(1), one U(7), and two equivalent Zr(3) atoms to form OZr2U2 tetrahedra that share  a cornercorner with one O(19)U4 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra,  a cornercorner with one O(7)Zr2U2 tetrahedra, corners with two equivalent O(6)Zr2U2 tetrahedra, corners with two equivalent O(13)ZrU3 tetrahedra, corners with two equivalent O(15)ZrU3 tetrahedra, corners with three equivalent O(18)Zr2U2 tetrahedra, corners with four equivalent O(2)Zr2U2 tetrahedra,  an edgeedge with one O(1)Zr2U2 tetrahedra,  an edgeedge with one O(18)Zr2U2 tetrahedra, edges with two equivalent O(5)Zr2U2 tetrahedra, and edges with two equivalent O(20)ZrU3 tetrahedra. In the seventh O site, O(7) is bonded to one U(1), one U(2), and two equivalent Zr(1) atoms to form OZr2U2 tetrahedra that share corners with two equivalent O(11)Mg2U3 square pyramids,  a cornercorner with one O(6)Zr2U2 tetrahedra, corners with two equivalent O(2)Zr2U2 tetrahedra, corners with two equivalent O(7)Zr2U2 tetrahedra, corners with three equivalent O(1)Zr2U2 tetrahedra, corners with four equivalent O(13)ZrU3 tetrahedra,  an edgeedge with one O(9)U4 tetrahedra,  an edgeedge with one O(1)Zr2U2 tetrahedra, edges with two equivalent O(5)Zr2U2 tetrahedra, and edges with two equivalent O(4)ZrU3 tetrahedra. In the eighth O site, O(8) is bonded to one U(5), two equivalent U(3), and one Zr(2) atom to form distorted OZrU3 tetrahedra that share  a cornercorner with one O(19)U4 tetrahedra,  a cornercorner with one O(18)Zr2U2 tetrahedra, corners with two equivalent O(15)ZrU3 tetrahedra, corners with two equivalent O(8)ZrU3 tetrahedra,  an edgeedge with one O(16)ZrU3 tetrahedra, and edges with two equivalent O(10)U4 tetrahedra. In the ninth O site, O(9) is bonded to one U(1), one U(2), and two equivalent U(4) atoms to form OU4 tetrahedra that share  a cornercorner with one O(1)Zr2U2 tetrahedra,  a cornercorner with one O(6)Zr2U2 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with two equivalent O(5)Zr2U2 tetrahedra, corners with four equivalent O(4)ZrU3 tetrahedra, edges with two equivalent O(11)Mg2U3 square pyramids,  an edgeedge with one O(7)Zr2U2 tetrahedra, and edges with two equivalent O(13)ZrU3 tetrahedra. In the tenth O site, O(10) is bonded to one U(3), one U(6), and two equivalent U(5) atoms to form OU4 tetrahedra that share  a cornercorner with one O(20)ZrU3 tetrahedra, corners with two equivalent O(10)U4 tetrahedra, corners with two equivalent O(18)Zr2U2 tetrahedra, corners with three equivalent O(15)ZrU3 tetrahedra, corners with four equivalent O(16)ZrU3 tetrahedra,  an edgeedge with one O(15)ZrU3 tetrahedra, edges with two equivalent O(19)U4 tetrahedra, and edges with two equivalent O(8)ZrU3 tetrahedra. In the eleventh O site, O(11) is bonded to two equivalent Mg(1), one U(4), and two equivalent U(2) atoms to form distorted OMg2U3 square pyramids that share  a cornercorner with one O(13)ZrU3 tetrahedra, corners with two equivalent O(7)Zr2U2 tetrahedra, corners with three equivalent O(4)ZrU3 tetrahedra, edges with two equivalent O(11)Mg2U3 square pyramids,  an edgeedge with one O(4)ZrU3 tetrahedra, and edges with two equivalent O(9)U4 tetrahedra. In the twelfth O site, O(12) is bonded in a distorted see-saw-like geometry to one Mg(1), one U(3), and two equivalent Zr(2) atoms. In the thirteenth O site, O(13) is bonded to one U(4), two equivalent U(1), and one Zr(1) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(11)Mg2U3 square pyramid,  a cornercorner with one O(2)Zr2U2 tetrahedra, corners with two equivalent O(6)Zr2U2 tetrahedra, corners with two equivalent O(13)ZrU3 tetrahedra, corners with three equivalent O(5)Zr2U2 tetrahedra, corners with four equivalent O(7)Zr2U2 tetrahedra,  an edgeedge with one O(5)Zr2U2 tetrahedra,  an edgeedge with one O(4)ZrU3 tetrahedra, edges with two equivalent O(9)U4 tetrahedra, and edges with two equivalent O(1)Zr2U2 tetrahedra. In the fourteenth O site, O(14) is bonded in a 5-coordinate geometry to one Mg(1), one U(3), one U(6), and two equivalent Zr(2) atoms. In the fifteenth O site, O(15) is bonded to one U(6), two equivalent U(5), and one Zr(3) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(2)Zr2U2 tetrahedra,  a cornercorner with one O(5)Zr2U2 tetrahedra, corners with two equivalent O(6)Zr2U2 tetrahedra, corners with two equivalent O(15)ZrU3 tetrahedra, corners with two equivalent O(8)ZrU3 tetrahedra, corners with three equivalent O(10)U4 tetrahedra, corners with four equivalent O(19)U4 tetrahedra,  an edgeedge with one O(10)U4 tetrahedra,  an edgeedge with one O(20)ZrU3 tetrahedra, edges with two equivalent O(18)Zr2U2 tetrahedra, and edges with two equivalent O(16)ZrU3 tetrahedra. In the sixteenth O site, O(16) is bonded to one U(5), two equivalent U(6), and one Zr(2) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(18)Zr2U2 tetrahedra, corners with two equivalent O(16)ZrU3 tetrahedra, corners with two equivalent O(20)ZrU3 tetrahedra, corners with three equivalent O(19)U4 tetrahedra, corners with four equivalent O(10)U4 tetrahedra,  an edgeedge with one O(19)U4 tetrahedra,  an edgeedge with one O(8)ZrU3 tetrahedra, and edges with two equivalent O(15)ZrU3 tetrahedra. In the seventeenth O site, O(17) is bonded in a 3-coordinate geometry to two equivalent Mg(1), two equivalent U(3), and one Zr(2) atom. In the eighteenth O site, O(18) is bonded to one U(5), one U(7), and two equivalent Zr(3) atoms to form OZr2U2 tetrahedra that share  a cornercorner with one O(1)Zr2U2 tetrahedra,  a cornercorner with one O(16)ZrU3 tetrahedra,  a cornercorner with one O(8)ZrU3 tetrahedra, corners with two equivalent O(10)U4 tetrahedra, corners with two equivalent O(18)Zr2U2 tetrahedra, corners with two equivalent O(5)Zr2U2 tetrahedra, corners with three equivalent O(6)Zr2U2 tetrahedra, corners with four equivalent O(20)ZrU3 tetrahedra,  an edgeedge with one O(19)U4 tetrahedra,  an edgeedge with one O(6)Zr2U2 tetrahedra, edges with two equivalent O(2)Zr2U2 tetrahedra, and edges with two equivalent O(15)ZrU3 tetrahedra. In the nineteenth O site, O(19) is bonded to one U(5), one U(7), and two equivalent U(6) atoms to form OU4 tetrahedra that share  a cornercorner with one O(1)Zr2U2 tetrahedra,  a cornercorner with one O(6)Zr2U2 tetrahedra,  a cornercorner with one O(8)ZrU3 tetrahedra, corners with two equivalent O(19)U4 tetrahedra, corners with two equivalent O(2)Zr2U2 tetrahedra, corners with three equivalent O(16)ZrU3 tetrahedra, corners with four equivalent O(15)ZrU3 tetrahedra,  an edgeedge with one O(18)Zr2U2 tetrahedra,  an edgeedge with one O(16)ZrU3 tetrahedra, edges with two equivalent O(10)U4 tetrahedra, and edges with two equivalent O(20)ZrU3 tetrahedra. In the twentieth O site, O(20) is bonded to one U(6), two equivalent U(7), and one Zr(3) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(10)U4 tetrahedra,  a cornercorner with one O(5)Zr2U2 tetrahedra, corners with two equivalent O(1)Zr2U2 tetrahedra, corners with two equivalent O(16)ZrU3 tetrahedra, corners with two equivalent O(20)ZrU3 tetrahedra, corners with three equivalent O(2)Zr2U2 tetrahedra, corners with four equivalent O(18)Zr2U2 tetrahedra,  an edgeedge with one O(2)Zr2U2 tetrahedra,  an edgeedge with one O(15)ZrU3 tetrahedra, edges with two equivalent O(19)U4 tetrahedra, and edges with two equivalent O(6)Zr2U2 tetrahedra. is represented by the CIF file [CIF]
data_MgZr3U7O20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.755
_cell_length_b   6.492
_cell_length_c   16.717
_cell_angle_alpha   92.301
_cell_angle_beta   96.460
_cell_angle_gamma   90.018
_symmetry_Int_Tables_number   1
_cell_volume   404.632
_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  0.747  0.252  0.491  1.0
  Zr  Zr1  1  0.408  0.806  0.815  1.0
  Zr  Zr2  1  0.183  0.382  0.363  1.0
  Zr  Zr3  1  0.499  0.498  0.999  1.0
  U  U4  1  0.907  0.311  0.814  1.0
  U  U5  1  0.812  0.625  0.625  1.0
  U  U6  1  0.692  0.861  0.383  1.0
  U  U7  1  0.315  0.118  0.629  1.0
  U  U8  1  0.093  0.689  0.185  1.0
  U  U9  1  0.594  0.184  0.186  1.0
  U  U10  1  0.999  0.997  0.997  1.0
  O  O11  1  0.930  0.972  0.858  1.0
  O  O12  1  0.475  0.817  0.949  1.0
  O  O13  1  0.780  0.971  0.558  1.0
  O  O14  1  0.336  0.795  0.672  1.0
  O  O15  1  0.431  0.490  0.861  1.0
  O  O16  1  0.978  0.337  0.953  1.0
  O  O17  1  0.883  0.646  0.765  1.0
  O  O18  1  0.171  0.705  0.341  1.0
  O  O19  1  0.837  0.294  0.674  1.0
  O  O20  1  0.621  0.852  0.241  1.0
  O  O21  1  0.287  0.439  0.574  1.0
  O  O22  1  0.717  0.522  0.434  1.0
  O  O23  1  0.385  0.129  0.769  1.0
  O  O24  1  0.668  0.207  0.334  1.0
  O  O25  1  0.568  0.514  0.135  1.0
  O  O26  1  0.120  0.362  0.237  1.0
  O  O27  1  0.225  0.145  0.448  1.0
  O  O28  1  0.022  0.664  0.043  1.0
  O  O29  1  0.070  0.015  0.140  1.0
  O  O30  1  0.522  0.175  0.043  1.0
[/CIF]
.
The crystal structure described by MgU7Zr3O20 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(12), one O(14), one O(3), two equivalent O(11), and two equivalent O(17) atoms. There are seven inequivalent U sites. In the first U site, U(1) is bonded in a body-centered cubic geometry to one O(1), one O(6), one O(7), one O(9), two equivalent O(13), and two equivalent O(5) atoms. In the second U site, U(2) is bonded in a 7-coordinate geometry to one O(3), one O(7), one O(9), two equivalent O(11), and two equivalent O(4) atoms. In the third U site, U(3) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(14), one O(3), two equivalent O(17), and two equivalent O(8) atoms. In the fourth U site, U(4) is bonded in a 7-coordinate geometry to one O(11), one O(13), one O(4), two equivalent O(3), and two equivalent O(9) atoms. In the fifth U site, U(5) is bonded in a body-centered cubic geometry to one O(16), one O(18), one O(19), one O(8), two equivalent O(10), and two equivalent O(15) atoms. In the sixth U site, U(6) is bonded in a body-centered cubic geometry to one O(10), one O(14), one O(15), one O(20), two equivalent O(16), and two equivalent O(19) atoms. In the seventh U site, U(7) is bonded in a body-centered cubic geometry to one O(1), one O(18), one O(19), one O(6), two equivalent O(2), and two equivalent O(20) atoms. There are three inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a body-centered cubic geometry to one O(13), one O(2), one O(4), one O(5), two equivalent O(1), and two equivalent O(7) atoms. In the second Zr site, Zr(2) is bonded in a 7-coordinate geometry to one O(16), one O(17), one O(8), two equivalent O(12), and two equivalent O(14) atoms. In the third Zr site, Zr(3) is bonded in a body-centered cubic geometry to one O(15), one O(2), one O(20), one O(5), two equivalent O(18), and two equivalent O(6) atoms. There are twenty inequivalent O sites. In the first O site, O(1) is bonded to one U(1), one U(7), and two equivalent Zr(1) atoms to form OZr2U2 tetrahedra that share  a cornercorner with one O(19)U4 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra,  a cornercorner with one O(18)Zr2U2 tetrahedra, corners with two equivalent O(1)Zr2U2 tetrahedra, corners with two equivalent O(20)ZrU3 tetrahedra, corners with two equivalent O(4)ZrU3 tetrahedra, corners with three equivalent O(7)Zr2U2 tetrahedra, corners with four equivalent O(5)Zr2U2 tetrahedra,  an edgeedge with one O(6)Zr2U2 tetrahedra,  an edgeedge with one O(7)Zr2U2 tetrahedra, edges with two equivalent O(2)Zr2U2 tetrahedra, and edges with two equivalent O(13)ZrU3 tetrahedra. In the second O site, O(2) is bonded to two equivalent U(7), one Zr(1), and one Zr(3) atom to form OZr2U2 tetrahedra that share  a cornercorner with one O(13)ZrU3 tetrahedra,  a cornercorner with one O(15)ZrU3 tetrahedra,  a cornercorner with one O(4)ZrU3 tetrahedra, corners with two equivalent O(19)U4 tetrahedra, corners with two equivalent O(2)Zr2U2 tetrahedra, corners with two equivalent O(7)Zr2U2 tetrahedra, corners with three equivalent O(20)ZrU3 tetrahedra, corners with four equivalent O(6)Zr2U2 tetrahedra,  an edgeedge with one O(5)Zr2U2 tetrahedra,  an edgeedge with one O(20)ZrU3 tetrahedra, edges with two equivalent O(1)Zr2U2 tetrahedra, and edges with two equivalent O(18)Zr2U2 tetrahedra. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(1), one U(2), one U(3), and two equivalent U(4) atoms. In the fourth O site, O(4) is bonded to one U(4), two equivalent U(2), and one Zr(1) atom to form OZrU3 tetrahedra that share corners with three equivalent O(11)Mg2U3 square pyramids,  a cornercorner with one O(2)Zr2U2 tetrahedra,  a cornercorner with one O(5)Zr2U2 tetrahedra, corners with two equivalent O(1)Zr2U2 tetrahedra, corners with two equivalent O(4)ZrU3 tetrahedra, corners with four equivalent O(9)U4 tetrahedra,  an edgeedge with one O(11)Mg2U3 square pyramid,  an edgeedge with one O(13)ZrU3 tetrahedra, and edges with two equivalent O(7)Zr2U2 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent U(1), one Zr(1), and one Zr(3) atom to form OZr2U2 tetrahedra that share  a cornercorner with one O(15)ZrU3 tetrahedra,  a cornercorner with one O(20)ZrU3 tetrahedra,  a cornercorner with one O(4)ZrU3 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with two equivalent O(18)Zr2U2 tetrahedra, corners with two equivalent O(5)Zr2U2 tetrahedra, corners with three equivalent O(13)ZrU3 tetrahedra, corners with four equivalent O(1)Zr2U2 tetrahedra,  an edgeedge with one O(2)Zr2U2 tetrahedra,  an edgeedge with one O(13)ZrU3 tetrahedra, edges with two equivalent O(6)Zr2U2 tetrahedra, and edges with two equivalent O(7)Zr2U2 tetrahedra. In the sixth O site, O(6) is bonded to one U(1), one U(7), and two equivalent Zr(3) atoms to form OZr2U2 tetrahedra that share  a cornercorner with one O(19)U4 tetrahedra,  a cornercorner with one O(9)U4 tetrahedra,  a cornercorner with one O(7)Zr2U2 tetrahedra, corners with two equivalent O(6)Zr2U2 tetrahedra, corners with two equivalent O(13)ZrU3 tetrahedra, corners with two equivalent O(15)ZrU3 tetrahedra, corners with three equivalent O(18)Zr2U2 tetrahedra, corners with four equivalent O(2)Zr2U2 tetrahedra,  an edgeedge with one O(1)Zr2U2 tetrahedra,  an edgeedge with one O(18)Zr2U2 tetrahedra, edges with two equivalent O(5)Zr2U2 tetrahedra, and edges with two equivalent O(20)ZrU3 tetrahedra. In the seventh O site, O(7) is bonded to one U(1), one U(2), and two equivalent Zr(1) atoms to form OZr2U2 tetrahedra that share corners with two equivalent O(11)Mg2U3 square pyramids,  a cornercorner with one O(6)Zr2U2 tetrahedra, corners with two equivalent O(2)Zr2U2 tetrahedra, corners with two equivalent O(7)Zr2U2 tetrahedra, corners with three equivalent O(1)Zr2U2 tetrahedra, corners with four equivalent O(13)ZrU3 tetrahedra,  an edgeedge with one O(9)U4 tetrahedra,  an edgeedge with one O(1)Zr2U2 tetrahedra, edges with two equivalent O(5)Zr2U2 tetrahedra, and edges with two equivalent O(4)ZrU3 tetrahedra. In the eighth O site, O(8) is bonded to one U(5), two equivalent U(3), and one Zr(2) atom to form distorted OZrU3 tetrahedra that share  a cornercorner with one O(19)U4 tetrahedra,  a cornercorner with one O(18)Zr2U2 tetrahedra, corners with two equivalent O(15)ZrU3 tetrahedra, corners with two equivalent O(8)ZrU3 tetrahedra,  an edgeedge with one O(16)ZrU3 tetrahedra, and edges with two equivalent O(10)U4 tetrahedra. In the ninth O site, O(9) is bonded to one U(1), one U(2), and two equivalent U(4) atoms to form OU4 tetrahedra that share  a cornercorner with one O(1)Zr2U2 tetrahedra,  a cornercorner with one O(6)Zr2U2 tetrahedra, corners with two equivalent O(9)U4 tetrahedra, corners with two equivalent O(5)Zr2U2 tetrahedra, corners with four equivalent O(4)ZrU3 tetrahedra, edges with two equivalent O(11)Mg2U3 square pyramids,  an edgeedge with one O(7)Zr2U2 tetrahedra, and edges with two equivalent O(13)ZrU3 tetrahedra. In the tenth O site, O(10) is bonded to one U(3), one U(6), and two equivalent U(5) atoms to form OU4 tetrahedra that share  a cornercorner with one O(20)ZrU3 tetrahedra, corners with two equivalent O(10)U4 tetrahedra, corners with two equivalent O(18)Zr2U2 tetrahedra, corners with three equivalent O(15)ZrU3 tetrahedra, corners with four equivalent O(16)ZrU3 tetrahedra,  an edgeedge with one O(15)ZrU3 tetrahedra, edges with two equivalent O(19)U4 tetrahedra, and edges with two equivalent O(8)ZrU3 tetrahedra. In the eleventh O site, O(11) is bonded to two equivalent Mg(1), one U(4), and two equivalent U(2) atoms to form distorted OMg2U3 square pyramids that share  a cornercorner with one O(13)ZrU3 tetrahedra, corners with two equivalent O(7)Zr2U2 tetrahedra, corners with three equivalent O(4)ZrU3 tetrahedra, edges with two equivalent O(11)Mg2U3 square pyramids,  an edgeedge with one O(4)ZrU3 tetrahedra, and edges with two equivalent O(9)U4 tetrahedra. In the twelfth O site, O(12) is bonded in a distorted see-saw-like geometry to one Mg(1), one U(3), and two equivalent Zr(2) atoms. In the thirteenth O site, O(13) is bonded to one U(4), two equivalent U(1), and one Zr(1) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(11)Mg2U3 square pyramid,  a cornercorner with one O(2)Zr2U2 tetrahedra, corners with two equivalent O(6)Zr2U2 tetrahedra, corners with two equivalent O(13)ZrU3 tetrahedra, corners with three equivalent O(5)Zr2U2 tetrahedra, corners with four equivalent O(7)Zr2U2 tetrahedra,  an edgeedge with one O(5)Zr2U2 tetrahedra,  an edgeedge with one O(4)ZrU3 tetrahedra, edges with two equivalent O(9)U4 tetrahedra, and edges with two equivalent O(1)Zr2U2 tetrahedra. In the fourteenth O site, O(14) is bonded in a 5-coordinate geometry to one Mg(1), one U(3), one U(6), and two equivalent Zr(2) atoms. In the fifteenth O site, O(15) is bonded to one U(6), two equivalent U(5), and one Zr(3) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(2)Zr2U2 tetrahedra,  a cornercorner with one O(5)Zr2U2 tetrahedra, corners with two equivalent O(6)Zr2U2 tetrahedra, corners with two equivalent O(15)ZrU3 tetrahedra, corners with two equivalent O(8)ZrU3 tetrahedra, corners with three equivalent O(10)U4 tetrahedra, corners with four equivalent O(19)U4 tetrahedra,  an edgeedge with one O(10)U4 tetrahedra,  an edgeedge with one O(20)ZrU3 tetrahedra, edges with two equivalent O(18)Zr2U2 tetrahedra, and edges with two equivalent O(16)ZrU3 tetrahedra. In the sixteenth O site, O(16) is bonded to one U(5), two equivalent U(6), and one Zr(2) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(18)Zr2U2 tetrahedra, corners with two equivalent O(16)ZrU3 tetrahedra, corners with two equivalent O(20)ZrU3 tetrahedra, corners with three equivalent O(19)U4 tetrahedra, corners with four equivalent O(10)U4 tetrahedra,  an edgeedge with one O(19)U4 tetrahedra,  an edgeedge with one O(8)ZrU3 tetrahedra, and edges with two equivalent O(15)ZrU3 tetrahedra. In the seventeenth O site, O(17) is bonded in a 3-coordinate geometry to two equivalent Mg(1), two equivalent U(3), and one Zr(2) atom. In the eighteenth O site, O(18) is bonded to one U(5), one U(7), and two equivalent Zr(3) atoms to form OZr2U2 tetrahedra that share  a cornercorner with one O(1)Zr2U2 tetrahedra,  a cornercorner with one O(16)ZrU3 tetrahedra,  a cornercorner with one O(8)ZrU3 tetrahedra, corners with two equivalent O(10)U4 tetrahedra, corners with two equivalent O(18)Zr2U2 tetrahedra, corners with two equivalent O(5)Zr2U2 tetrahedra, corners with three equivalent O(6)Zr2U2 tetrahedra, corners with four equivalent O(20)ZrU3 tetrahedra,  an edgeedge with one O(19)U4 tetrahedra,  an edgeedge with one O(6)Zr2U2 tetrahedra, edges with two equivalent O(2)Zr2U2 tetrahedra, and edges with two equivalent O(15)ZrU3 tetrahedra. In the nineteenth O site, O(19) is bonded to one U(5), one U(7), and two equivalent U(6) atoms to form OU4 tetrahedra that share  a cornercorner with one O(1)Zr2U2 tetrahedra,  a cornercorner with one O(6)Zr2U2 tetrahedra,  a cornercorner with one O(8)ZrU3 tetrahedra, corners with two equivalent O(19)U4 tetrahedra, corners with two equivalent O(2)Zr2U2 tetrahedra, corners with three equivalent O(16)ZrU3 tetrahedra, corners with four equivalent O(15)ZrU3 tetrahedra,  an edgeedge with one O(18)Zr2U2 tetrahedra,  an edgeedge with one O(16)ZrU3 tetrahedra, edges with two equivalent O(10)U4 tetrahedra, and edges with two equivalent O(20)ZrU3 tetrahedra. In the twentieth O site, O(20) is bonded to one U(6), two equivalent U(7), and one Zr(3) atom to form OZrU3 tetrahedra that share  a cornercorner with one O(10)U4 tetrahedra,  a cornercorner with one O(5)Zr2U2 tetrahedra, corners with two equivalent O(1)Zr2U2 tetrahedra, corners with two equivalent O(16)ZrU3 tetrahedra, corners with two equivalent O(20)ZrU3 tetrahedra, corners with three equivalent O(2)Zr2U2 tetrahedra, corners with four equivalent O(18)Zr2U2 tetrahedra,  an edgeedge with one O(2)Zr2U2 tetrahedra,  an edgeedge with one O(15)ZrU3 tetrahedra, edges with two equivalent O(19)U4 tetrahedra, and edges with two equivalent O(6)Zr2U2 tetrahedra. is represented by the CIF file [CIF]
data_MgZr3U7O20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.755
_cell_length_b   6.492
_cell_length_c   16.717
_cell_angle_alpha   92.301
_cell_angle_beta   96.460
_cell_angle_gamma   90.018
_symmetry_Int_Tables_number   1
_cell_volume   404.632
_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  0.747  0.252  0.491  1.0
  Zr  Zr1  1  0.408  0.806  0.815  1.0
  Zr  Zr2  1  0.183  0.382  0.363  1.0
  Zr  Zr3  1  0.499  0.498  0.999  1.0
  U  U4  1  0.907  0.311  0.814  1.0
  U  U5  1  0.812  0.625  0.625  1.0
  U  U6  1  0.692  0.861  0.383  1.0
  U  U7  1  0.315  0.118  0.629  1.0
  U  U8  1  0.093  0.689  0.185  1.0
  U  U9  1  0.594  0.184  0.186  1.0
  U  U10  1  0.999  0.997  0.997  1.0
  O  O11  1  0.930  0.972  0.858  1.0
  O  O12  1  0.475  0.817  0.949  1.0
  O  O13  1  0.780  0.971  0.558  1.0
  O  O14  1  0.336  0.795  0.672  1.0
  O  O15  1  0.431  0.490  0.861  1.0
  O  O16  1  0.978  0.337  0.953  1.0
  O  O17  1  0.883  0.646  0.765  1.0
  O  O18  1  0.171  0.705  0.341  1.0
  O  O19  1  0.837  0.294  0.674  1.0
  O  O20  1  0.621  0.852  0.241  1.0
  O  O21  1  0.287  0.439  0.574  1.0
  O  O22  1  0.717  0.522  0.434  1.0
  O  O23  1  0.385  0.129  0.769  1.0
  O  O24  1  0.668  0.207  0.334  1.0
  O  O25  1  0.568  0.514  0.135  1.0
  O  O26  1  0.120  0.362  0.237  1.0
  O  O27  1  0.225  0.145  0.448  1.0
  O  O28  1  0.022  0.664  0.043  1.0
  O  O29  1  0.070  0.015  0.140  1.0
  O  O30  1  0.522  0.175  0.043  1.0
[/CIF]
.