The material structure described by Al3Si2O7(OH)3 crystallizes in the triclinic P-1 space group. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(4), one O(6), one O(9), and two equivalent O(1) 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, and  an edgeedge with one Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to one O(10), one O(3), one O(5), one O(9), and two equivalent O(2) atoms to form AlO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, and  an edgeedge with one Al(2)O6 octahedra. In the third Al site, Al(3) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(5), one O(6), and one O(7) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(2), one O(4), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra and corners with three equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-58°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Al(2)O6 octahedra and corners with three equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(7) and one O(8) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one O(5) and one O(7) atom. There are ten inequivalent O sites. In the first O site, O(9) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(2) atom. In the second O site, O(10) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(2) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Al(2) and one Si(1) atom. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to one Al(2), one Al(3), and one Si(2) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(3), and one Si(1) atom. In the seventh O site, O(5) is bonded in a distorted trigonal planar geometry to one Al(2), one Al(3), and one H(3) atom. In the eighth O site, O(6) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(3), and one H(2) atom. In the ninth O site, O(7) is bonded in a 4-coordinate geometry to one Al(3), one Si(2), one H(1), and one H(3) atom. In the tenth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one H(1) atom. is represented by the CIF file [CIF]
data_Al3Si2H3O10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.189
_cell_length_b   7.339
_cell_length_c   7.813
_cell_angle_alpha   64.603
_cell_angle_beta   88.016
_cell_angle_gamma   86.637
_symmetry_Int_Tables_number   1
_cell_volume   319.990
_cell_formula_units_Z   2
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  0.154  0.149  0.396  1.0
  Al  Al1  1  0.846  0.851  0.604  1.0
  Al  Al2  1  0.656  0.649  0.394  1.0
  Al  Al3  1  0.344  0.351  0.606  1.0
  Al  Al4  1  0.716  0.745  0.990  1.0
  Al  Al5  1  0.284  0.255  0.010  1.0
  Si  Si6  1  0.864  0.221  0.704  1.0
  Si  Si7  1  0.136  0.779  0.296  1.0
  Si  Si8  1  0.373  0.725  0.709  1.0
  Si  Si9  1  0.627  0.275  0.291  1.0
  H  H10  1  0.798  0.236  0.984  1.0
  H  H11  1  0.202  0.764  0.016  1.0
  H  H12  1  0.121  0.499  0.132  1.0
  H  H13  1  0.879  0.501  0.868  1.0
  H  H14  1  0.630  1.000  0.133  1.0
  H  H15  1  0.370  0.000  0.867  1.0
  O  O16  1  0.849  0.111  0.399  1.0
  O  O17  1  0.151  0.889  0.601  1.0
  O  O18  1  0.350  0.609  0.403  1.0
  O  O19  1  0.650  0.391  0.597  1.0
  O  O20  1  0.308  0.488  0.776  1.0
  O  O21  1  0.692  0.512  0.224  1.0
  O  O22  1  0.797  0.987  0.770  1.0
  O  O23  1  0.203  0.013  0.230  1.0
  O  O24  1  0.366  0.139  0.847  1.0
  O  O25  1  0.634  0.861  0.153  1.0
  O  O26  1  0.866  0.638  0.846  1.0
  O  O27  1  0.134  0.362  0.154  1.0
  O  O28  1  0.577  0.238  0.105  1.0
  O  O29  1  0.423  0.762  0.895  1.0
  O  O30  1  0.087  0.745  0.104  1.0
  O  O31  1  0.913  0.255  0.896  1.0
  O  O32  1  0.432  0.215  0.441  1.0
  O  O33  1  0.568  0.785  0.559  1.0
  O  O34  1  0.935  0.717  0.436  1.0
  O  O35  1  0.065  0.283  0.564  1.0
[/CIF]
.
The material structure described by Al3Si2O7(OH)3 crystallizes in the triclinic P-1 space group. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(4), one O(6), one O(9), and two equivalent O(1) 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, and  an edgeedge with one Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to one O(10), one O(3), one O(5), one O(9), and two equivalent O(2) atoms to form AlO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Al(1)O6 octahedra, and  an edgeedge with one Al(2)O6 octahedra. In the third Al site, Al(3) is bonded in a 5-coordinate geometry to one O(3), one O(4), one O(5), one O(6), and one O(7) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(2), one O(4), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra and corners with three equivalent Al(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-58°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Al(2)O6 octahedra and corners with three equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(7) and one O(8) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one O(5) and one O(7) atom. There are ten inequivalent O sites. In the first O site, O(9) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(2) atom. In the second O site, O(10) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(2) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Al(2) and one Si(1) atom. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to one Al(2), one Al(3), and one Si(2) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(3), and one Si(1) atom. In the seventh O site, O(5) is bonded in a distorted trigonal planar geometry to one Al(2), one Al(3), and one H(3) atom. In the eighth O site, O(6) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(3), and one H(2) atom. In the ninth O site, O(7) is bonded in a 4-coordinate geometry to one Al(3), one Si(2), one H(1), and one H(3) atom. In the tenth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one H(1) atom. is represented by the CIF file [CIF]
data_Al3Si2H3O10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.189
_cell_length_b   7.339
_cell_length_c   7.813
_cell_angle_alpha   64.603
_cell_angle_beta   88.016
_cell_angle_gamma   86.637
_symmetry_Int_Tables_number   1
_cell_volume   319.990
_cell_formula_units_Z   2
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  0.154  0.149  0.396  1.0
  Al  Al1  1  0.846  0.851  0.604  1.0
  Al  Al2  1  0.656  0.649  0.394  1.0
  Al  Al3  1  0.344  0.351  0.606  1.0
  Al  Al4  1  0.716  0.745  0.990  1.0
  Al  Al5  1  0.284  0.255  0.010  1.0
  Si  Si6  1  0.864  0.221  0.704  1.0
  Si  Si7  1  0.136  0.779  0.296  1.0
  Si  Si8  1  0.373  0.725  0.709  1.0
  Si  Si9  1  0.627  0.275  0.291  1.0
  H  H10  1  0.798  0.236  0.984  1.0
  H  H11  1  0.202  0.764  0.016  1.0
  H  H12  1  0.121  0.499  0.132  1.0
  H  H13  1  0.879  0.501  0.868  1.0
  H  H14  1  0.630  1.000  0.133  1.0
  H  H15  1  0.370  0.000  0.867  1.0
  O  O16  1  0.849  0.111  0.399  1.0
  O  O17  1  0.151  0.889  0.601  1.0
  O  O18  1  0.350  0.609  0.403  1.0
  O  O19  1  0.650  0.391  0.597  1.0
  O  O20  1  0.308  0.488  0.776  1.0
  O  O21  1  0.692  0.512  0.224  1.0
  O  O22  1  0.797  0.987  0.770  1.0
  O  O23  1  0.203  0.013  0.230  1.0
  O  O24  1  0.366  0.139  0.847  1.0
  O  O25  1  0.634  0.861  0.153  1.0
  O  O26  1  0.866  0.638  0.846  1.0
  O  O27  1  0.134  0.362  0.154  1.0
  O  O28  1  0.577  0.238  0.105  1.0
  O  O29  1  0.423  0.762  0.895  1.0
  O  O30  1  0.087  0.745  0.104  1.0
  O  O31  1  0.913  0.255  0.896  1.0
  O  O32  1  0.432  0.215  0.441  1.0
  O  O33  1  0.568  0.785  0.559  1.0
  O  O34  1  0.935  0.717  0.436  1.0
  O  O35  1  0.065  0.283  0.564  1.0
[/CIF]
.