The material structure described by Al2SiO5 crystallizes in the triclinic P-1 space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(10), one O(3), one O(5), and one O(8) atom to form AlO5 trigonal bipyramids that share corners with two equivalent Al(4)O5 square pyramids,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Al(2)O5 trigonal bipyramid,  an edgeedge with one Si(1)O6 octahedra, and edges with two equivalent Al(3)O5 trigonal bipyramids. In the second Al site, Al(2) is bonded to one O(10), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. In the third Al site, Al(3) is bonded to one O(1), one O(10), one O(2), one O(5), and one O(8) atom to form AlO5 trigonal bipyramids that share  a cornercorner with one Si(1)O6 octahedra,  a cornercorner with one Al(4)O5 square pyramid,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Al(2)O5 trigonal bipyramid,  an edgeedge with one Al(2)O5 trigonal bipyramid, and edges with two equivalent Al(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. In the fourth Al site, Al(4) is bonded to one O(3), one O(4), one O(6), one O(8), and one O(9) atom to form distorted AlO5 square pyramids that share corners with three equivalent Si(1)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid, corners with two equivalent Al(1)O5 trigonal bipyramids, and corners with two equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 31-51°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(5), one O(6), one O(9), and two equivalent O(7) atoms to form SiO6 octahedra that share corners with three equivalent Al(4)O5 square pyramids, corners with two equivalent Si(2)O4 tetrahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid,  an edgeedge with one Si(1)O6 octahedra,  an edgeedge with one Si(2)O4 tetrahedra, and  an edgeedge with one Al(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(6), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Si(1)O6 octahedra, corners with two equivalent Al(4)O5 square pyramids,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Al(3)O5 trigonal bipyramid, and  an edgeedge with one Si(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-66°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Al(1), one Al(3), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Al(3) and two equivalent Al(2) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(4) and two equivalent Al(2) atoms. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Al(1), one Al(3), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Al(4), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Si(2) and two equivalent Si(1) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Al(1), one Al(3), and one Al(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Al(4), one Si(1), and one Si(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Al(1), one Al(2), and one Al(3) atom. is represented by the CIF card [CIF]
data_Al2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.333
_cell_length_b   8.570
_cell_length_c   8.628
_cell_angle_alpha   69.915
_cell_angle_beta   78.334
_cell_angle_gamma   79.254
_symmetry_Int_Tables_number   1
_cell_volume   359.723
_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
  Al  Al0  1  0.220  0.828  0.687  1.0
  Al  Al1  1  0.738  0.997  0.053  1.0
  Al  Al2  1  0.321  0.185  0.196  1.0
  Al  Al3  1  0.679  0.815  0.804  1.0
  Al  Al4  1  0.115  0.823  0.331  1.0
  Al  Al5  1  0.262  0.003  0.947  1.0
  Al  Al6  1  0.885  0.177  0.669  1.0
  Al  Al7  1  0.780  0.172  0.313  1.0
  Si  Si8  1  0.581  0.609  0.572  1.0
  Si  Si9  1  0.021  0.553  0.665  1.0
  Si  Si10  1  0.979  0.447  0.335  1.0
  Si  Si11  1  0.419  0.391  0.428  1.0
  O  O12  1  0.004  0.650  0.799  1.0
  O  O13  1  0.400  0.150  0.998  1.0
  O  O14  1  0.654  0.231  0.514  1.0
  O  O15  1  0.600  0.850  0.002  1.0
  O  O16  1  0.945  0.125  0.878  1.0
  O  O17  1  0.511  0.673  0.746  1.0
  O  O18  1  0.489  0.327  0.254  1.0
  O  O19  1  0.877  0.709  0.505  1.0
  O  O20  1  0.996  0.350  0.201  1.0
  O  O21  1  0.674  0.536  0.382  1.0
  O  O22  1  0.123  0.291  0.495  1.0
  O  O23  1  0.912  0.958  0.676  1.0
  O  O24  1  0.326  0.464  0.618  1.0
  O  O25  1  0.346  0.769  0.486  1.0
  O  O26  1  0.055  0.875  0.122  1.0
  O  O27  1  0.800  0.433  0.681  1.0
  O  O28  1  0.088  0.042  0.324  1.0
  O  O29  1  0.200  0.567  0.319  1.0
  O  O30  1  0.628  0.042  0.247  1.0
  O  O31  1  0.372  0.958  0.753  1.0
[/CIF]
.
The material structure described by Al2SiO5 crystallizes in the triclinic P-1 space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(10), one O(3), one O(5), and one O(8) atom to form AlO5 trigonal bipyramids that share corners with two equivalent Al(4)O5 square pyramids,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Al(2)O5 trigonal bipyramid,  an edgeedge with one Si(1)O6 octahedra, and edges with two equivalent Al(3)O5 trigonal bipyramids. In the second Al site, Al(2) is bonded to one O(10), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. In the third Al site, Al(3) is bonded to one O(1), one O(10), one O(2), one O(5), and one O(8) atom to form AlO5 trigonal bipyramids that share  a cornercorner with one Si(1)O6 octahedra,  a cornercorner with one Al(4)O5 square pyramid,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Al(2)O5 trigonal bipyramid,  an edgeedge with one Al(2)O5 trigonal bipyramid, and edges with two equivalent Al(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. In the fourth Al site, Al(4) is bonded to one O(3), one O(4), one O(6), one O(8), and one O(9) atom to form distorted AlO5 square pyramids that share corners with three equivalent Si(1)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid, corners with two equivalent Al(1)O5 trigonal bipyramids, and corners with two equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 31-51°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(5), one O(6), one O(9), and two equivalent O(7) atoms to form SiO6 octahedra that share corners with three equivalent Al(4)O5 square pyramids, corners with two equivalent Si(2)O4 tetrahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid,  an edgeedge with one Si(1)O6 octahedra,  an edgeedge with one Si(2)O4 tetrahedra, and  an edgeedge with one Al(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(6), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Si(1)O6 octahedra, corners with two equivalent Al(4)O5 square pyramids,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Al(3)O5 trigonal bipyramid, and  an edgeedge with one Si(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-66°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal non-coplanar geometry to one Al(1), one Al(3), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Al(3) and two equivalent Al(2) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(4) and two equivalent Al(2) atoms. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Al(1), one Al(3), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Al(4), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Si(2) and two equivalent Si(1) atoms. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Al(1), one Al(3), and one Al(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Al(4), one Si(1), and one Si(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Al(1), one Al(2), and one Al(3) atom. is represented by the CIF card [CIF]
data_Al2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.333
_cell_length_b   8.570
_cell_length_c   8.628
_cell_angle_alpha   69.915
_cell_angle_beta   78.334
_cell_angle_gamma   79.254
_symmetry_Int_Tables_number   1
_cell_volume   359.723
_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
  Al  Al0  1  0.220  0.828  0.687  1.0
  Al  Al1  1  0.738  0.997  0.053  1.0
  Al  Al2  1  0.321  0.185  0.196  1.0
  Al  Al3  1  0.679  0.815  0.804  1.0
  Al  Al4  1  0.115  0.823  0.331  1.0
  Al  Al5  1  0.262  0.003  0.947  1.0
  Al  Al6  1  0.885  0.177  0.669  1.0
  Al  Al7  1  0.780  0.172  0.313  1.0
  Si  Si8  1  0.581  0.609  0.572  1.0
  Si  Si9  1  0.021  0.553  0.665  1.0
  Si  Si10  1  0.979  0.447  0.335  1.0
  Si  Si11  1  0.419  0.391  0.428  1.0
  O  O12  1  0.004  0.650  0.799  1.0
  O  O13  1  0.400  0.150  0.998  1.0
  O  O14  1  0.654  0.231  0.514  1.0
  O  O15  1  0.600  0.850  0.002  1.0
  O  O16  1  0.945  0.125  0.878  1.0
  O  O17  1  0.511  0.673  0.746  1.0
  O  O18  1  0.489  0.327  0.254  1.0
  O  O19  1  0.877  0.709  0.505  1.0
  O  O20  1  0.996  0.350  0.201  1.0
  O  O21  1  0.674  0.536  0.382  1.0
  O  O22  1  0.123  0.291  0.495  1.0
  O  O23  1  0.912  0.958  0.676  1.0
  O  O24  1  0.326  0.464  0.618  1.0
  O  O25  1  0.346  0.769  0.486  1.0
  O  O26  1  0.055  0.875  0.122  1.0
  O  O27  1  0.800  0.433  0.681  1.0
  O  O28  1  0.088  0.042  0.324  1.0
  O  O29  1  0.200  0.567  0.319  1.0
  O  O30  1  0.628  0.042  0.247  1.0
  O  O31  1  0.372  0.958  0.753  1.0
[/CIF]
.