The material described by K2Al2(SiO4)3 crystallizes in the triclinic P1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(11), one O(14), one O(21), one O(22), one O(5), and one O(6) atom. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(12), one O(13), one O(21), one O(22), one O(5), and one O(6) atom. In the third K site, K(3) is bonded in a 6-coordinate geometry to one O(16), one O(23), one O(24), one O(7), one O(8), and one O(9) atom. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to one O(10), one O(15), one O(23), one O(24), one O(7), and one O(8) atom. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(13), one O(3), one O(5), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(10), one O(14), one O(4), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the third Al site, Al(3) is bonded to one O(1), one O(11), one O(15), and one O(7) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the fourth Al site, Al(4) is bonded to one O(12), one O(16), one O(2), and one O(8) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(17), one O(18), and one O(2) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(19), one O(20), one O(3), and one O(4) 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(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(14), one O(20), one O(7), 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 Al(3)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(10), one O(13), one O(19), and one O(8) 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 Al(4)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. In the fifth Si site, Si(5) is bonded to one O(11), one O(16), one O(18), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  a cornercorner with one Si(1)O4 tetrahedra. In the sixth Si site, Si(6) is bonded to one O(12), one O(15), one O(17), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  a cornercorner with one Si(1)O4 tetrahedra. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Al(3) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(4) and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Al(1), and one Si(5) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Al(2), and one Si(6) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one K(3), one K(4), one Al(3), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one K(3), one K(4), one Al(4), and one Si(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one K(3), one Al(1), and one Si(3) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one K(4), one Al(2), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one K(1), one Al(3), and one Si(5) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one K(2), one Al(4), and one Si(6) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one K(2), one Al(1), and one Si(4) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one K(1), one Al(2), and one Si(3) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one K(4), one Al(3), and one Si(6) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one K(3), one Al(4), and one Si(5) atom. In the seventeenth O site, O(17) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(6) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(5) atom. In the nineteenth O site, O(19) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the twentieth O site, O(20) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the twenty-first O site, O(21) is bonded in a 2-coordinate geometry to one K(1) and one K(2) atom. In the twenty-second O site, O(22) is bonded in a 2-coordinate geometry to one K(1) and one K(2) atom. In the twenty-third O site, O(23) is bonded in a 2-coordinate geometry to one K(3) and one K(4) atom. In the twenty-fourth O site, O(24) is bonded in a 2-coordinate geometry to one K(3) and one K(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Al2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.757
_cell_length_b   10.059
_cell_length_c   10.179
_cell_angle_alpha   83.572
_cell_angle_beta   70.663
_cell_angle_gamma   70.461
_symmetry_Int_Tables_number   1
_cell_volume   615.277
_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
  K  K0  1  0.888  0.968  0.536  1.0
  K  K1  1  0.396  0.032  0.463  1.0
  K  K2  1  0.603  0.534  0.034  1.0
  K  K3  1  0.172  0.468  0.966  1.0
  Al  Al4  1  0.335  0.915  0.178  1.0
  Al  Al5  1  0.428  0.086  0.823  1.0
  Al  Al6  1  1.000  0.587  0.679  1.0
  Al  Al7  1  0.262  0.416  0.323  1.0
  Si  Si8  1  0.741  0.501  0.501  1.0
  Si  Si9  1  0.990  0.002  0.002  1.0
  Si  Si10  1  0.757  0.821  0.911  1.0
  Si  Si11  1  0.488  0.181  0.091  1.0
  Si  Si12  1  0.327  0.681  0.411  1.0
  Si  Si13  1  0.417  0.321  0.591  1.0
  O  O14  1  0.792  0.559  0.626  1.0
  O  O15  1  0.975  0.442  0.376  1.0
  O  O16  1  0.100  0.943  0.127  1.0
  O  O17  1  0.166  0.061  0.877  1.0
  O  O18  1  0.293  0.841  0.347  1.0
  O  O19  1  0.477  0.161  0.655  1.0
  O  O20  1  0.884  0.661  0.847  1.0
  O  O21  1  0.386  0.341  0.155  1.0
  O  O22  1  0.568  0.808  0.056  1.0
  O  O23  1  0.434  0.194  0.945  1.0
  O  O24  1  0.124  0.694  0.555  1.0
  O  O25  1  0.376  0.307  0.445  1.0
  O  O26  1  0.377  0.075  0.200  1.0
  O  O27  1  0.649  0.926  0.801  1.0
  O  O28  1  0.200  0.427  0.700  1.0
  O  O29  1  0.326  0.575  0.301  1.0
  O  O30  1  0.635  0.373  0.563  1.0
  O  O31  1  0.567  0.628  0.441  1.0
  O  O32  1  0.757  0.130  0.064  1.0
  O  O33  1  0.942  0.876  0.940  1.0
  O  O34  1  0.855  0.840  0.289  1.0
  O  O35  1  0.980  0.166  0.711  1.0
  O  O36  1  0.447  0.653  0.787  1.0
  O  O37  1  0.889  0.333  0.208  1.0
[/CIF]
.
The material described by K2Al2(SiO4)3 crystallizes in the triclinic P1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(11), one O(14), one O(21), one O(22), one O(5), and one O(6) atom. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(12), one O(13), one O(21), one O(22), one O(5), and one O(6) atom. In the third K site, K(3) is bonded in a 6-coordinate geometry to one O(16), one O(23), one O(24), one O(7), one O(8), and one O(9) atom. In the fourth K site, K(4) is bonded in a 6-coordinate geometry to one O(10), one O(15), one O(23), one O(24), one O(7), and one O(8) atom. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(13), one O(3), one O(5), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(10), one O(14), one O(4), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the third Al site, Al(3) is bonded to one O(1), one O(11), one O(15), and one O(7) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the fourth Al site, Al(4) is bonded to one O(12), one O(16), one O(2), and one O(8) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(17), one O(18), and one O(2) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(19), one O(20), one O(3), and one O(4) 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(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(14), one O(20), one O(7), 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 Al(3)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(10), one O(13), one O(19), and one O(8) 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 Al(4)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. In the fifth Si site, Si(5) is bonded to one O(11), one O(16), one O(18), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  a cornercorner with one Si(1)O4 tetrahedra. In the sixth Si site, Si(6) is bonded to one O(12), one O(15), one O(17), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  a cornercorner with one Si(1)O4 tetrahedra. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Al(3) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(4) and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Al(1), and one Si(5) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Al(2), and one Si(6) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one K(3), one K(4), one Al(3), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one K(3), one K(4), one Al(4), and one Si(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one K(3), one Al(1), and one Si(3) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one K(4), one Al(2), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one K(1), one Al(3), and one Si(5) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one K(2), one Al(4), and one Si(6) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one K(2), one Al(1), and one Si(4) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one K(1), one Al(2), and one Si(3) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one K(4), one Al(3), and one Si(6) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one K(3), one Al(4), and one Si(5) atom. In the seventeenth O site, O(17) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(6) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(5) atom. In the nineteenth O site, O(19) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the twentieth O site, O(20) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the twenty-first O site, O(21) is bonded in a 2-coordinate geometry to one K(1) and one K(2) atom. In the twenty-second O site, O(22) is bonded in a 2-coordinate geometry to one K(1) and one K(2) atom. In the twenty-third O site, O(23) is bonded in a 2-coordinate geometry to one K(3) and one K(4) atom. In the twenty-fourth O site, O(24) is bonded in a 2-coordinate geometry to one K(3) and one K(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Al2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.757
_cell_length_b   10.059
_cell_length_c   10.179
_cell_angle_alpha   83.572
_cell_angle_beta   70.663
_cell_angle_gamma   70.461
_symmetry_Int_Tables_number   1
_cell_volume   615.277
_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
  K  K0  1  0.888  0.968  0.536  1.0
  K  K1  1  0.396  0.032  0.463  1.0
  K  K2  1  0.603  0.534  0.034  1.0
  K  K3  1  0.172  0.468  0.966  1.0
  Al  Al4  1  0.335  0.915  0.178  1.0
  Al  Al5  1  0.428  0.086  0.823  1.0
  Al  Al6  1  1.000  0.587  0.679  1.0
  Al  Al7  1  0.262  0.416  0.323  1.0
  Si  Si8  1  0.741  0.501  0.501  1.0
  Si  Si9  1  0.990  0.002  0.002  1.0
  Si  Si10  1  0.757  0.821  0.911  1.0
  Si  Si11  1  0.488  0.181  0.091  1.0
  Si  Si12  1  0.327  0.681  0.411  1.0
  Si  Si13  1  0.417  0.321  0.591  1.0
  O  O14  1  0.792  0.559  0.626  1.0
  O  O15  1  0.975  0.442  0.376  1.0
  O  O16  1  0.100  0.943  0.127  1.0
  O  O17  1  0.166  0.061  0.877  1.0
  O  O18  1  0.293  0.841  0.347  1.0
  O  O19  1  0.477  0.161  0.655  1.0
  O  O20  1  0.884  0.661  0.847  1.0
  O  O21  1  0.386  0.341  0.155  1.0
  O  O22  1  0.568  0.808  0.056  1.0
  O  O23  1  0.434  0.194  0.945  1.0
  O  O24  1  0.124  0.694  0.555  1.0
  O  O25  1  0.376  0.307  0.445  1.0
  O  O26  1  0.377  0.075  0.200  1.0
  O  O27  1  0.649  0.926  0.801  1.0
  O  O28  1  0.200  0.427  0.700  1.0
  O  O29  1  0.326  0.575  0.301  1.0
  O  O30  1  0.635  0.373  0.563  1.0
  O  O31  1  0.567  0.628  0.441  1.0
  O  O32  1  0.757  0.130  0.064  1.0
  O  O33  1  0.942  0.876  0.940  1.0
  O  O34  1  0.855  0.840  0.289  1.0
  O  O35  1  0.980  0.166  0.711  1.0
  O  O36  1  0.447  0.653  0.787  1.0
  O  O37  1  0.889  0.333  0.208  1.0
[/CIF]
.