The material structure described by MgAl2SiHO7 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(7) atoms to form distorted MgO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, edges with three equivalent Mg(1)O6 octahedra, and edges with three equivalent Al(3)O6 octahedra. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with four equivalent Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(2)O6 octahedra. In the third Al site, Al(3) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(7) atoms to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and edges with six equivalent Mg(1)O6 octahedra. Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(3)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Al(1)O6 octahedra, and corners with four equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-61°. H(1) is bonded in a linear geometry to one O(6) and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Mg(1), one Al(3), and one H(1) atom. In the second O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Al(2) and one Si(1) atom. In the third O site, O(2) is bonded in a trigonal non-coplanar geometry to two equivalent Mg(1) and one Al(3) atom. In the fourth O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1), one Al(3), and one Si(1) atom. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the sixth O site, O(5) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the seventh O site, O(6) is bonded to one Al(1), two equivalent Al(2), and one H(1) atom to form corner-sharing OAl3H tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgAl2SiHO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.532
_cell_length_b   5.532
_cell_length_c   17.992
_cell_angle_alpha   80.153
_cell_angle_beta   80.153
_cell_angle_gamma   60.109
_symmetry_Int_Tables_number   1
_cell_volume   467.957
_cell_formula_units_Z   4
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  0.672  0.167  0.000  1.0
  Mg  Mg1  1  0.328  0.833  1.000  1.0
  Mg  Mg2  1  0.833  0.328  0.500  1.0
  Mg  Mg3  1  0.167  0.672  0.500  1.0
  Al  Al4  1  0.902  0.098  0.750  1.0
  Al  Al5  1  0.098  0.902  0.250  1.0
  Al  Al6  1  0.403  0.097  0.750  1.0
  Al  Al7  1  0.597  0.903  0.250  1.0
  Al  Al8  1  0.903  0.597  0.750  1.0
  Al  Al9  1  0.097  0.403  0.250  1.0
  Al  Al10  1  0.500  0.000  0.500  1.0
  Al  Al11  1  0.000  0.500  0.000  1.0
  Si  Si12  1  0.438  0.633  0.656  1.0
  Si  Si13  1  0.562  0.367  0.344  1.0
  Si  Si14  1  0.367  0.562  0.844  1.0
  Si  Si15  1  0.633  0.438  0.156  1.0
  H  H16  1  0.765  0.965  0.611  1.0
  H  H17  1  0.235  0.035  0.389  1.0
  H  H18  1  0.035  0.235  0.889  1.0
  H  H19  1  0.965  0.765  0.111  1.0
  O  O20  1  0.542  0.736  0.813  1.0
  O  O21  1  0.458  0.264  0.187  1.0
  O  O22  1  0.264  0.458  0.687  1.0
  O  O23  1  0.736  0.542  0.313  1.0
  O  O24  1  0.706  0.825  0.954  1.0
  O  O25  1  0.294  0.175  0.046  1.0
  O  O26  1  0.175  0.294  0.546  1.0
  O  O27  1  0.825  0.706  0.454  1.0
  O  O28  1  0.471  0.672  0.562  1.0
  O  O29  1  0.529  0.328  0.438  1.0
  O  O30  1  0.328  0.529  0.938  1.0
  O  O31  1  0.672  0.471  0.062  1.0
  O  O32  1  0.542  0.248  0.813  1.0
  O  O33  1  0.458  0.752  0.187  1.0
  O  O34  1  0.752  0.458  0.687  1.0
  O  O35  1  0.248  0.542  0.313  1.0
  O  O36  1  0.264  0.947  0.688  1.0
  O  O37  1  0.736  0.053  0.312  1.0
  O  O38  1  0.053  0.736  0.812  1.0
  O  O39  1  0.947  0.264  0.188  1.0
  O  O40  1  0.754  0.949  0.701  1.0
  O  O41  1  0.246  0.051  0.299  1.0
  O  O42  1  0.051  0.246  0.799  1.0
  O  O43  1  0.949  0.754  0.201  1.0
  O  O44  1  0.781  0.987  0.553  1.0
  O  O45  1  0.219  0.013  0.447  1.0
  O  O46  1  0.013  0.219  0.947  1.0
  O  O47  1  0.987  0.781  0.053  1.0
[/CIF]
.
The material structure described by MgAl2SiHO7 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(7) atoms to form distorted MgO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, edges with three equivalent Mg(1)O6 octahedra, and edges with three equivalent Al(3)O6 octahedra. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with four equivalent Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(2)O6 octahedra. In the third Al site, Al(3) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(7) atoms to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and edges with six equivalent Mg(1)O6 octahedra. Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(3)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Al(1)O6 octahedra, and corners with four equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-61°. H(1) is bonded in a linear geometry to one O(6) and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Mg(1), one Al(3), and one H(1) atom. In the second O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Al(2) and one Si(1) atom. In the third O site, O(2) is bonded in a trigonal non-coplanar geometry to two equivalent Mg(1) and one Al(3) atom. In the fourth O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1), one Al(3), and one Si(1) atom. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the sixth O site, O(5) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the seventh O site, O(6) is bonded to one Al(1), two equivalent Al(2), and one H(1) atom to form corner-sharing OAl3H tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgAl2SiHO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.532
_cell_length_b   5.532
_cell_length_c   17.992
_cell_angle_alpha   80.153
_cell_angle_beta   80.153
_cell_angle_gamma   60.109
_symmetry_Int_Tables_number   1
_cell_volume   467.957
_cell_formula_units_Z   4
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  0.672  0.167  0.000  1.0
  Mg  Mg1  1  0.328  0.833  1.000  1.0
  Mg  Mg2  1  0.833  0.328  0.500  1.0
  Mg  Mg3  1  0.167  0.672  0.500  1.0
  Al  Al4  1  0.902  0.098  0.750  1.0
  Al  Al5  1  0.098  0.902  0.250  1.0
  Al  Al6  1  0.403  0.097  0.750  1.0
  Al  Al7  1  0.597  0.903  0.250  1.0
  Al  Al8  1  0.903  0.597  0.750  1.0
  Al  Al9  1  0.097  0.403  0.250  1.0
  Al  Al10  1  0.500  0.000  0.500  1.0
  Al  Al11  1  0.000  0.500  0.000  1.0
  Si  Si12  1  0.438  0.633  0.656  1.0
  Si  Si13  1  0.562  0.367  0.344  1.0
  Si  Si14  1  0.367  0.562  0.844  1.0
  Si  Si15  1  0.633  0.438  0.156  1.0
  H  H16  1  0.765  0.965  0.611  1.0
  H  H17  1  0.235  0.035  0.389  1.0
  H  H18  1  0.035  0.235  0.889  1.0
  H  H19  1  0.965  0.765  0.111  1.0
  O  O20  1  0.542  0.736  0.813  1.0
  O  O21  1  0.458  0.264  0.187  1.0
  O  O22  1  0.264  0.458  0.687  1.0
  O  O23  1  0.736  0.542  0.313  1.0
  O  O24  1  0.706  0.825  0.954  1.0
  O  O25  1  0.294  0.175  0.046  1.0
  O  O26  1  0.175  0.294  0.546  1.0
  O  O27  1  0.825  0.706  0.454  1.0
  O  O28  1  0.471  0.672  0.562  1.0
  O  O29  1  0.529  0.328  0.438  1.0
  O  O30  1  0.328  0.529  0.938  1.0
  O  O31  1  0.672  0.471  0.062  1.0
  O  O32  1  0.542  0.248  0.813  1.0
  O  O33  1  0.458  0.752  0.187  1.0
  O  O34  1  0.752  0.458  0.687  1.0
  O  O35  1  0.248  0.542  0.313  1.0
  O  O36  1  0.264  0.947  0.688  1.0
  O  O37  1  0.736  0.053  0.312  1.0
  O  O38  1  0.053  0.736  0.812  1.0
  O  O39  1  0.947  0.264  0.188  1.0
  O  O40  1  0.754  0.949  0.701  1.0
  O  O41  1  0.246  0.051  0.299  1.0
  O  O42  1  0.051  0.246  0.799  1.0
  O  O43  1  0.949  0.754  0.201  1.0
  O  O44  1  0.781  0.987  0.553  1.0
  O  O45  1  0.219  0.013  0.447  1.0
  O  O46  1  0.013  0.219  0.947  1.0
  O  O47  1  0.987  0.781  0.053  1.0
[/CIF]
.