The compound described by RbAlSi3O8 crystallizes in the monoclinic C2 space group. Rb(1) is bonded in a 10-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(8), one O(9), and two equivalent O(7) atoms. Al(1) is bonded to one O(1), one O(5), one O(7), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(2), one O(4), 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 Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Si(1), and one Si(2) atom. In the second O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Al(1), and one Si(3) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Rb(1), one Al(1), and one Si(2) atom. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Rb(1), one Si(1), and one Si(3) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Rb(1) and two equivalent Si(2) atoms. In the sixth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Rb(1) and two equivalent Si(3) atoms. In the seventh O site, O(5) is bonded in a 2-coordinate geometry to one Rb(1), one Al(1), and one Si(2) atom. In the eighth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Si(1), and one Si(3) atom. In the ninth O site, O(7) is bonded in a distorted bent 150 degrees geometry to two equivalent Rb(1), one Al(1), and one Si(1) atom. is represented by the CIF file [CIF]
data_RbAlSi3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.017
_cell_length_b   8.017
_cell_length_c   7.230
_cell_angle_alpha   76.014
_cell_angle_beta   76.014
_cell_angle_gamma   112.266
_symmetry_Int_Tables_number   1
_cell_volume   387.486
_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
  Rb  Rb0  1  0.290  0.303  0.856  1.0
  Rb  Rb1  1  0.697  0.710  0.144  1.0
  Al  Al2  1  0.604  0.842  0.652  1.0
  Al  Al3  1  0.158  0.396  0.348  1.0
  Si  Si4  1  0.848  0.607  0.651  1.0
  Si  Si5  1  0.393  0.152  0.349  1.0
  Si  Si6  1  0.822  0.202  0.773  1.0
  Si  Si7  1  0.201  0.814  0.778  1.0
  Si  Si8  1  0.186  0.799  0.222  1.0
  Si  Si9  1  0.798  0.178  0.227  1.0
  O  O10  1  0.663  0.999  0.783  1.0
  O  O11  1  0.988  0.676  0.779  1.0
  O  O12  1  0.324  0.012  0.221  1.0
  O  O13  1  0.001  0.337  0.217  1.0
  O  O14  1  0.835  0.165  0.000  1.0
  O  O15  1  0.156  0.844  0.000  1.0
  O  O16  1  0.039  0.279  0.614  1.0
  O  O17  1  0.287  0.030  0.599  1.0
  O  O18  1  0.970  0.713  0.401  1.0
  O  O19  1  0.721  0.961  0.386  1.0
  O  O20  1  0.669  0.655  0.717  1.0
  O  O21  1  0.345  0.331  0.283  1.0
  O  O22  1  0.753  0.372  0.716  1.0
  O  O23  1  0.348  0.724  0.736  1.0
  O  O24  1  0.276  0.652  0.264  1.0
  O  O25  1  0.628  0.247  0.284  1.0
[/CIF]
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The compound described by RbAlSi3O8 crystallizes in the monoclinic C2 space group. Rb(1) is bonded in a 10-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(8), one O(9), and two equivalent O(7) atoms. Al(1) is bonded to one O(1), one O(5), one O(7), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(2), one O(4), 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 Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Si(1), and one Si(2) atom. In the second O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Rb(1), one Al(1), and one Si(3) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Rb(1), one Al(1), and one Si(2) atom. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Rb(1), one Si(1), and one Si(3) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Rb(1) and two equivalent Si(2) atoms. In the sixth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Rb(1) and two equivalent Si(3) atoms. In the seventh O site, O(5) is bonded in a 2-coordinate geometry to one Rb(1), one Al(1), and one Si(2) atom. In the eighth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Si(1), and one Si(3) atom. In the ninth O site, O(7) is bonded in a distorted bent 150 degrees geometry to two equivalent Rb(1), one Al(1), and one Si(1) atom. is represented by the CIF file [CIF]
data_RbAlSi3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.017
_cell_length_b   8.017
_cell_length_c   7.230
_cell_angle_alpha   76.014
_cell_angle_beta   76.014
_cell_angle_gamma   112.266
_symmetry_Int_Tables_number   1
_cell_volume   387.486
_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
  Rb  Rb0  1  0.290  0.303  0.856  1.0
  Rb  Rb1  1  0.697  0.710  0.144  1.0
  Al  Al2  1  0.604  0.842  0.652  1.0
  Al  Al3  1  0.158  0.396  0.348  1.0
  Si  Si4  1  0.848  0.607  0.651  1.0
  Si  Si5  1  0.393  0.152  0.349  1.0
  Si  Si6  1  0.822  0.202  0.773  1.0
  Si  Si7  1  0.201  0.814  0.778  1.0
  Si  Si8  1  0.186  0.799  0.222  1.0
  Si  Si9  1  0.798  0.178  0.227  1.0
  O  O10  1  0.663  0.999  0.783  1.0
  O  O11  1  0.988  0.676  0.779  1.0
  O  O12  1  0.324  0.012  0.221  1.0
  O  O13  1  0.001  0.337  0.217  1.0
  O  O14  1  0.835  0.165  0.000  1.0
  O  O15  1  0.156  0.844  0.000  1.0
  O  O16  1  0.039  0.279  0.614  1.0
  O  O17  1  0.287  0.030  0.599  1.0
  O  O18  1  0.970  0.713  0.401  1.0
  O  O19  1  0.721  0.961  0.386  1.0
  O  O20  1  0.669  0.655  0.717  1.0
  O  O21  1  0.345  0.331  0.283  1.0
  O  O22  1  0.753  0.372  0.716  1.0
  O  O23  1  0.348  0.724  0.736  1.0
  O  O24  1  0.276  0.652  0.264  1.0
  O  O25  1  0.628  0.247  0.284  1.0
[/CIF]
.