The compound described by CaAl2Si4(HO6)2 crystallizes in the monoclinic C2 space group. Ca(1) is bonded in a 4-coordinate geometry to one H(1), one H(2), one O(3), one O(5), one O(7), and one O(9) atom. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(3), one O(8), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(11), one O(12), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(12), one O(6), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(11), one O(2), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one Ca(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one Ca(1) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. is represented by the CIF card [CIF]
data_CaAl2Si4(HO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.043
_cell_length_b   10.043
_cell_length_c   7.587
_cell_angle_alpha   74.099
_cell_angle_beta   74.099
_cell_angle_gamma   83.459
_symmetry_Int_Tables_number   1
_cell_volume   707.140
_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
  Ca  Ca0  1  0.354  0.136  0.756  1.0
  Ca  Ca1  1  0.864  0.646  0.244  1.0
  Al  Al2  1  0.174  0.571  0.239  1.0
  Al  Al3  1  0.429  0.826  0.761  1.0
  Al  Al4  1  0.787  0.958  0.230  1.0
  Al  Al5  1  0.042  0.213  0.770  1.0
  Si  Si6  1  0.231  0.249  0.344  1.0
  Si  Si7  1  0.751  0.769  0.656  1.0
  Si  Si8  1  0.467  0.017  0.337  1.0
  Si  Si9  1  0.983  0.533  0.663  1.0
  Si  Si10  1  0.308  0.857  0.174  1.0
  Si  Si11  1  0.143  0.692  0.826  1.0
  Si  Si12  1  0.075  0.090  0.177  1.0
  Si  Si13  1  0.910  0.925  0.823  1.0
  H  H14  1  0.619  0.624  0.149  1.0
  H  H15  1  0.376  0.381  0.851  1.0
  H  H16  1  0.630  0.144  0.746  1.0
  H  H17  1  0.856  0.370  0.254  1.0
  O  O18  1  0.416  0.886  0.285  1.0
  O  O19  1  0.114  0.584  0.715  1.0
  O  O20  1  0.912  0.068  0.218  1.0
  O  O21  1  0.932  0.088  0.782  1.0
  O  O22  1  0.081  0.627  0.057  1.0
  O  O23  1  0.373  0.919  0.943  1.0
  O  O24  1  0.161  0.943  0.235  1.0
  O  O25  1  0.057  0.839  0.765  1.0
  O  O26  1  0.780  0.803  0.423  1.0
  O  O27  1  0.197  0.220  0.577  1.0
  O  O28  1  0.627  0.044  0.233  1.0
  O  O29  1  0.956  0.373  0.767  1.0
  O  O30  1  0.839  0.862  0.052  1.0
  O  O31  1  0.138  0.161  0.948  1.0
  O  O32  1  0.286  0.694  0.225  1.0
  O  O33  1  0.306  0.714  0.775  1.0
  O  O34  1  0.439  0.982  0.570  1.0
  O  O35  1  0.018  0.561  0.430  1.0
  O  O36  1  0.257  0.410  0.243  1.0
  O  O37  1  0.590  0.743  0.757  1.0
  O  O38  1  0.805  0.901  0.705  1.0
  O  O39  1  0.099  0.195  0.295  1.0
  O  O40  1  0.373  0.158  0.269  1.0
  O  O41  1  0.842  0.627  0.731  1.0
[/CIF]
.
The compound described by CaAl2Si4(HO6)2 crystallizes in the monoclinic C2 space group. Ca(1) is bonded in a 4-coordinate geometry to one H(1), one H(2), one O(3), one O(5), one O(7), and one O(9) atom. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(3), one O(8), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(11), one O(12), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(12), one O(6), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(11), one O(2), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one Ca(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one Ca(1) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. is represented by the CIF card [CIF]
data_CaAl2Si4(HO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.043
_cell_length_b   10.043
_cell_length_c   7.587
_cell_angle_alpha   74.099
_cell_angle_beta   74.099
_cell_angle_gamma   83.459
_symmetry_Int_Tables_number   1
_cell_volume   707.140
_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
  Ca  Ca0  1  0.354  0.136  0.756  1.0
  Ca  Ca1  1  0.864  0.646  0.244  1.0
  Al  Al2  1  0.174  0.571  0.239  1.0
  Al  Al3  1  0.429  0.826  0.761  1.0
  Al  Al4  1  0.787  0.958  0.230  1.0
  Al  Al5  1  0.042  0.213  0.770  1.0
  Si  Si6  1  0.231  0.249  0.344  1.0
  Si  Si7  1  0.751  0.769  0.656  1.0
  Si  Si8  1  0.467  0.017  0.337  1.0
  Si  Si9  1  0.983  0.533  0.663  1.0
  Si  Si10  1  0.308  0.857  0.174  1.0
  Si  Si11  1  0.143  0.692  0.826  1.0
  Si  Si12  1  0.075  0.090  0.177  1.0
  Si  Si13  1  0.910  0.925  0.823  1.0
  H  H14  1  0.619  0.624  0.149  1.0
  H  H15  1  0.376  0.381  0.851  1.0
  H  H16  1  0.630  0.144  0.746  1.0
  H  H17  1  0.856  0.370  0.254  1.0
  O  O18  1  0.416  0.886  0.285  1.0
  O  O19  1  0.114  0.584  0.715  1.0
  O  O20  1  0.912  0.068  0.218  1.0
  O  O21  1  0.932  0.088  0.782  1.0
  O  O22  1  0.081  0.627  0.057  1.0
  O  O23  1  0.373  0.919  0.943  1.0
  O  O24  1  0.161  0.943  0.235  1.0
  O  O25  1  0.057  0.839  0.765  1.0
  O  O26  1  0.780  0.803  0.423  1.0
  O  O27  1  0.197  0.220  0.577  1.0
  O  O28  1  0.627  0.044  0.233  1.0
  O  O29  1  0.956  0.373  0.767  1.0
  O  O30  1  0.839  0.862  0.052  1.0
  O  O31  1  0.138  0.161  0.948  1.0
  O  O32  1  0.286  0.694  0.225  1.0
  O  O33  1  0.306  0.714  0.775  1.0
  O  O34  1  0.439  0.982  0.570  1.0
  O  O35  1  0.018  0.561  0.430  1.0
  O  O36  1  0.257  0.410  0.243  1.0
  O  O37  1  0.590  0.743  0.757  1.0
  O  O38  1  0.805  0.901  0.705  1.0
  O  O39  1  0.099  0.195  0.295  1.0
  O  O40  1  0.373  0.158  0.269  1.0
  O  O41  1  0.842  0.627  0.731  1.0
[/CIF]
.