The crystal 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(10), one O(3), one O(6), one O(8), and two equivalent O(7) atoms to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra,  an edgeedge with one Al(2)O6 octahedra,  an edgeedge with one Al(3)O6 octahedra, and  an edgeedge with one Al(4)O6 octahedra. In the second Al site, Al(2) is bonded to one O(4), one O(6), one O(8), one O(9), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with two equivalent Al(3)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra,  an edgeedge with one Al(2)O6 octahedra,  an edgeedge with one Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-18°. In the third Al site, Al(3) is bonded to one O(1), one O(10), one O(2), one O(5), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with two equivalent Al(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra,  an edgeedge with one Al(2)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-18°. In the fourth Al site, Al(4) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(8) atom to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, corners with two equivalent Al(3)O6 octahedra, and corners with two equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-54°. In the second Si site, Si(2) is bonded to one O(1), one O(10), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Al(3)O6 octahedra, corners with two equivalent Al(4)O6 octahedra, and corners with three equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Al(3), one Al(4), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Al(3), one Al(4), and one Si(1) atom. 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(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(2), one Al(4), and one Si(1) atom. In the fifth O site, O(5) is bonded to one Al(3), one Al(4), and two equivalent Al(2) atoms to form edge-sharing OAl4 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. In the eighth O site, O(8) is bonded in a see-saw-like geometry to one Al(1), one Al(2), 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(2), one Al(3), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(3), and one Si(2) atom. is represented by the CIF card [CIF]
data_Al2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.565
_cell_length_b   7.118
_cell_length_c   7.846
_cell_angle_alpha   105.994
_cell_angle_beta   89.993
_cell_angle_gamma   101.111
_symmetry_Int_Tables_number   1
_cell_volume   292.713
_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  0.836  0.889  0.083  1.0
  Al  Al1  1  0.164  0.111  0.917  1.0
  Al  Al2  1  0.360  0.901  0.614  1.0
  Al  Al3  1  0.640  0.099  0.386  1.0
  Al  Al4  1  0.050  0.703  0.301  1.0
  Al  Al5  1  0.950  0.297  0.699  1.0
  Al  Al6  1  0.542  0.675  0.296  1.0
  Al  Al7  1  0.458  0.325  0.704  1.0
  Si  Si8  1  0.811  0.709  0.668  1.0
  Si  Si9  1  0.189  0.291  0.332  1.0
  Si  Si10  1  0.293  0.704  0.935  1.0
  Si  Si11  1  0.707  0.296  0.065  1.0
  O  O12  1  0.244  0.498  0.769  1.0
  O  O13  1  0.756  0.502  0.231  1.0
  O  O14  1  0.756  0.499  0.725  1.0
  O  O15  1  0.244  0.501  0.275  1.0
  O  O16  1  0.535  0.709  0.054  1.0
  O  O17  1  0.465  0.291  0.946  1.0
  O  O18  1  0.571  0.718  0.554  1.0
  O  O19  1  0.429  0.282  0.446  1.0
  O  O20  1  0.361  0.879  0.369  1.0
  O  O21  1  0.639  0.121  0.631  1.0
  O  O22  1  0.333  0.892  0.848  1.0
  O  O23  1  0.667  0.108  0.152  1.0
  O  O24  1  0.129  0.109  0.147  1.0
  O  O25  1  0.871  0.891  0.853  1.0
  O  O26  1  0.181  0.122  0.685  1.0
  O  O27  1  0.819  0.878  0.315  1.0
  O  O28  1  0.954  0.275  0.455  1.0
  O  O29  1  0.046  0.725  0.545  1.0
  O  O30  1  0.936  0.283  0.935  1.0
  O  O31  1  0.064  0.717  0.065  1.0
[/CIF]
.
The crystal 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(10), one O(3), one O(6), one O(8), and two equivalent O(7) atoms to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra,  an edgeedge with one Al(2)O6 octahedra,  an edgeedge with one Al(3)O6 octahedra, and  an edgeedge with one Al(4)O6 octahedra. In the second Al site, Al(2) is bonded to one O(4), one O(6), one O(8), one O(9), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with two equivalent Al(3)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra,  an edgeedge with one Al(2)O6 octahedra,  an edgeedge with one Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-18°. In the third Al site, Al(3) is bonded to one O(1), one O(10), one O(2), one O(5), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with two equivalent Al(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra,  an edgeedge with one Al(2)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-18°. In the fourth Al site, Al(4) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(8) atom to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, corners with two equivalent Al(3)O6 octahedra, and corners with two equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-54°. In the second Si site, Si(2) is bonded to one O(1), one O(10), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Al(3)O6 octahedra, corners with two equivalent Al(4)O6 octahedra, and corners with three equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-56°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Al(3), one Al(4), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Al(3), one Al(4), and one Si(1) atom. 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(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(2), one Al(4), and one Si(1) atom. In the fifth O site, O(5) is bonded to one Al(3), one Al(4), and two equivalent Al(2) atoms to form edge-sharing OAl4 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. In the eighth O site, O(8) is bonded in a see-saw-like geometry to one Al(1), one Al(2), 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(2), one Al(3), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(3), and one Si(2) atom. is represented by the CIF card [CIF]
data_Al2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.565
_cell_length_b   7.118
_cell_length_c   7.846
_cell_angle_alpha   105.994
_cell_angle_beta   89.993
_cell_angle_gamma   101.111
_symmetry_Int_Tables_number   1
_cell_volume   292.713
_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  0.836  0.889  0.083  1.0
  Al  Al1  1  0.164  0.111  0.917  1.0
  Al  Al2  1  0.360  0.901  0.614  1.0
  Al  Al3  1  0.640  0.099  0.386  1.0
  Al  Al4  1  0.050  0.703  0.301  1.0
  Al  Al5  1  0.950  0.297  0.699  1.0
  Al  Al6  1  0.542  0.675  0.296  1.0
  Al  Al7  1  0.458  0.325  0.704  1.0
  Si  Si8  1  0.811  0.709  0.668  1.0
  Si  Si9  1  0.189  0.291  0.332  1.0
  Si  Si10  1  0.293  0.704  0.935  1.0
  Si  Si11  1  0.707  0.296  0.065  1.0
  O  O12  1  0.244  0.498  0.769  1.0
  O  O13  1  0.756  0.502  0.231  1.0
  O  O14  1  0.756  0.499  0.725  1.0
  O  O15  1  0.244  0.501  0.275  1.0
  O  O16  1  0.535  0.709  0.054  1.0
  O  O17  1  0.465  0.291  0.946  1.0
  O  O18  1  0.571  0.718  0.554  1.0
  O  O19  1  0.429  0.282  0.446  1.0
  O  O20  1  0.361  0.879  0.369  1.0
  O  O21  1  0.639  0.121  0.631  1.0
  O  O22  1  0.333  0.892  0.848  1.0
  O  O23  1  0.667  0.108  0.152  1.0
  O  O24  1  0.129  0.109  0.147  1.0
  O  O25  1  0.871  0.891  0.853  1.0
  O  O26  1  0.181  0.122  0.685  1.0
  O  O27  1  0.819  0.878  0.315  1.0
  O  O28  1  0.954  0.275  0.455  1.0
  O  O29  1  0.046  0.725  0.545  1.0
  O  O30  1  0.936  0.283  0.935  1.0
  O  O31  1  0.064  0.717  0.065  1.0
[/CIF]
.