The compound described by K2MgFe(SiO3)8 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one O(10), one O(11), one O(12), one O(3), one O(4), one O(7), one O(8), one O(9), two equivalent O(1), and two equivalent O(5) atoms to form distorted KO12 cuboctahedra that share edges with two equivalent K(1)O12 cuboctahedra, edges with four equivalent K(2)O12 cuboctahedra,  an edgeedge with one Si(2)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra,  an edgeedge with one Si(6)O4 tetrahedra,  an edgeedge with one Si(8)O4 tetrahedra, edges with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Si(3)O4 tetrahedra, edges with two equivalent Si(5)O4 tetrahedra, and edges with two equivalent Si(7)O4 tetrahedra. In the second K site, K(2) is bonded to one O(10), one O(11), one O(12), one O(3), one O(4), one O(7), one O(8), one O(9), two equivalent O(2), and two equivalent O(6) atoms to form KO12 cuboctahedra that share edges with two equivalent K(2)O12 cuboctahedra, edges with four equivalent K(1)O12 cuboctahedra,  an edgeedge with one Si(1)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra,  an edgeedge with one Si(5)O4 tetrahedra,  an edgeedge with one Si(7)O4 tetrahedra, edges with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Si(4)O4 tetrahedra, edges with two equivalent Si(6)O4 tetrahedra, and edges with two equivalent Si(8)O4 tetrahedra. Mg(1) is bonded in a 6-coordinate geometry to one O(14), one O(16), one O(18), one O(19), one O(22), and one O(24) atom. Fe(1) is bonded to one O(13), one O(15), one O(17), one O(20), one O(21), and one O(23) atom to form distorted FeO6 octahedra 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(7)O4 tetrahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(17), one O(3), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. In the second Si site, Si(2) is bonded to one O(10), one O(18), one O(2), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(19), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. In the fourth Si site, Si(4) is bonded to one O(2), one O(20), one O(3), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 48°. In the fifth Si site, Si(5) is bonded to one O(11), one O(21), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(7)O4 tetrahedra, corners with two equivalent Si(8)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 47°. In the sixth Si site, Si(6) is bonded to one O(12), one O(22), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(8)O4 tetrahedra, corners with two equivalent Si(7)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. In the seventh Si site, Si(7) is bonded to one O(12), one O(23), one O(5), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(5)O4 tetrahedra, corners with two equivalent Si(6)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. In the eighth Si site, Si(8) is bonded to one O(11), one O(24), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(6)O4 tetrahedra, corners with two equivalent Si(5)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Si(1), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2), one Si(2), and one Si(4) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Si(1), and one Si(4) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Si(2), and one Si(3) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one Si(5), and one Si(7) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent K(2), one Si(6), and one Si(8) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(5), and one Si(8) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Si(6), and one Si(7) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(1), and one Si(4) atom. In the tenth O site, O(10) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Si(2), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(5), and one Si(8) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(6), and one Si(7) atom. In the thirteenth O site, O(13) is bonded in a single-bond geometry to one Fe(1) atom. In the fourteenth O site, O(14) is bonded in a single-bond geometry to one Mg(1) atom. In the fifteenth O site, O(15) is bonded in a single-bond geometry to one Fe(1) atom. In the sixteenth O site, O(16) is bonded in a single-bond geometry to one Mg(1) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Si(1) atom. In the eighteenth O site, O(18) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Si(2) atom. In the nineteenth O site, O(19) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Si(3) atom. In the twentieth O site, O(20) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one Si(4) atom. In the twenty-first O site, O(21) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one Si(5) atom. In the twenty-second O site, O(22) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Si(6) atom. In the twenty-third O site, O(23) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Si(7) atom. In the twenty-fourth O site, O(24) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Si(8) atom. is represented by the CIF card [CIF]
data_K2MgFe(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.248
_cell_length_b   9.104
_cell_length_c   10.965
_cell_angle_alpha   100.305
_cell_angle_beta   97.486
_cell_angle_gamma   89.899
_symmetry_Int_Tables_number   1
_cell_volume   510.890
_cell_formula_units_Z   1
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  0.260  0.248  0.502  1.0
  K  K1  1  0.760  0.745  0.503  1.0
  Mg  Mg2  1  0.407  0.857  0.002  1.0
  Fe  Fe3  1  0.944  0.350  0.999  1.0
  Si  Si4  1  0.723  0.367  0.273  1.0
  Si  Si5  1  0.209  0.869  0.280  1.0
  Si  Si6  1  0.706  0.033  0.279  1.0
  Si  Si7  1  0.214  0.531  0.275  1.0
  Si  Si8  1  0.810  0.126  0.722  1.0
  Si  Si9  1  0.311  0.626  0.726  1.0
  Si  Si10  1  0.809  0.454  0.724  1.0
  Si  Si11  1  0.312  0.955  0.724  1.0
  O  O12  1  0.714  0.214  0.334  1.0
  O  O13  1  0.214  0.712  0.335  1.0
  O  O14  1  0.992  0.459  0.343  1.0
  O  O15  1  0.482  0.959  0.346  1.0
  O  O16  1  0.799  0.275  0.655  1.0
  O  O17  1  0.305  0.775  0.657  1.0
  O  O18  1  0.537  0.034  0.663  1.0
  O  O19  1  0.037  0.535  0.667  1.0
  O  O20  1  0.495  0.473  0.332  1.0
  O  O21  1  0.980  0.970  0.342  1.0
  O  O22  1  0.035  0.018  0.665  1.0
  O  O23  1  0.536  0.521  0.666  1.0
  O  O24  1  0.147  0.254  0.134  1.0
  O  O25  1  0.784  0.768  0.091  1.0
  O  O26  1  0.195  0.294  0.870  1.0
  O  O27  1  0.710  0.780  0.888  1.0
  O  O28  1  0.705  0.339  0.123  1.0
  O  O29  1  0.180  0.845  0.130  1.0
  O  O30  1  0.652  0.996  0.129  1.0
  O  O31  1  0.168  0.500  0.124  1.0
  O  O32  1  0.839  0.164  0.874  1.0
  O  O33  1  0.339  0.663  0.877  1.0
  O  O34  1  0.843  0.476  0.874  1.0
  O  O35  1  0.353  0.980  0.873  1.0
[/CIF]
.
The compound described by K2MgFe(SiO3)8 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one O(10), one O(11), one O(12), one O(3), one O(4), one O(7), one O(8), one O(9), two equivalent O(1), and two equivalent O(5) atoms to form distorted KO12 cuboctahedra that share edges with two equivalent K(1)O12 cuboctahedra, edges with four equivalent K(2)O12 cuboctahedra,  an edgeedge with one Si(2)O4 tetrahedra,  an edgeedge with one Si(4)O4 tetrahedra,  an edgeedge with one Si(6)O4 tetrahedra,  an edgeedge with one Si(8)O4 tetrahedra, edges with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Si(3)O4 tetrahedra, edges with two equivalent Si(5)O4 tetrahedra, and edges with two equivalent Si(7)O4 tetrahedra. In the second K site, K(2) is bonded to one O(10), one O(11), one O(12), one O(3), one O(4), one O(7), one O(8), one O(9), two equivalent O(2), and two equivalent O(6) atoms to form KO12 cuboctahedra that share edges with two equivalent K(2)O12 cuboctahedra, edges with four equivalent K(1)O12 cuboctahedra,  an edgeedge with one Si(1)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra,  an edgeedge with one Si(5)O4 tetrahedra,  an edgeedge with one Si(7)O4 tetrahedra, edges with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Si(4)O4 tetrahedra, edges with two equivalent Si(6)O4 tetrahedra, and edges with two equivalent Si(8)O4 tetrahedra. Mg(1) is bonded in a 6-coordinate geometry to one O(14), one O(16), one O(18), one O(19), one O(22), and one O(24) atom. Fe(1) is bonded to one O(13), one O(15), one O(17), one O(20), one O(21), and one O(23) atom to form distorted FeO6 octahedra 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(7)O4 tetrahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(17), one O(3), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. In the second Si site, Si(2) is bonded to one O(10), one O(18), one O(2), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(19), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. In the fourth Si site, Si(4) is bonded to one O(2), one O(20), one O(3), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 48°. In the fifth Si site, Si(5) is bonded to one O(11), one O(21), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(7)O4 tetrahedra, corners with two equivalent Si(8)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 47°. In the sixth Si site, Si(6) is bonded to one O(12), one O(22), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(8)O4 tetrahedra, corners with two equivalent Si(7)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. In the seventh Si site, Si(7) is bonded to one O(12), one O(23), one O(5), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Si(5)O4 tetrahedra, corners with two equivalent Si(6)O4 tetrahedra,  an edgeedge with one K(2)O12 cuboctahedra, and edges with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 44°. In the eighth Si site, Si(8) is bonded to one O(11), one O(24), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(6)O4 tetrahedra, corners with two equivalent Si(5)O4 tetrahedra,  an edgeedge with one K(1)O12 cuboctahedra, and edges with two equivalent K(2)O12 cuboctahedra. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Si(1), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2), one Si(2), and one Si(4) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Si(1), and one Si(4) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Si(2), and one Si(3) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one Si(5), and one Si(7) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent K(2), one Si(6), and one Si(8) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(5), and one Si(8) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Si(6), and one Si(7) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(1), and one Si(4) atom. In the tenth O site, O(10) is bonded in a distorted bent 120 degrees geometry to one K(1), one K(2), one Si(2), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(5), and one Si(8) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(6), and one Si(7) atom. In the thirteenth O site, O(13) is bonded in a single-bond geometry to one Fe(1) atom. In the fourteenth O site, O(14) is bonded in a single-bond geometry to one Mg(1) atom. In the fifteenth O site, O(15) is bonded in a single-bond geometry to one Fe(1) atom. In the sixteenth O site, O(16) is bonded in a single-bond geometry to one Mg(1) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Si(1) atom. In the eighteenth O site, O(18) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Si(2) atom. In the nineteenth O site, O(19) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Si(3) atom. In the twentieth O site, O(20) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one Si(4) atom. In the twenty-first O site, O(21) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one Si(5) atom. In the twenty-second O site, O(22) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Si(6) atom. In the twenty-third O site, O(23) is bonded in a distorted bent 150 degrees geometry to one Fe(1) and one Si(7) atom. In the twenty-fourth O site, O(24) is bonded in a distorted bent 150 degrees geometry to one Mg(1) and one Si(8) atom. is represented by the CIF card [CIF]
data_K2MgFe(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.248
_cell_length_b   9.104
_cell_length_c   10.965
_cell_angle_alpha   100.305
_cell_angle_beta   97.486
_cell_angle_gamma   89.899
_symmetry_Int_Tables_number   1
_cell_volume   510.890
_cell_formula_units_Z   1
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  0.260  0.248  0.502  1.0
  K  K1  1  0.760  0.745  0.503  1.0
  Mg  Mg2  1  0.407  0.857  0.002  1.0
  Fe  Fe3  1  0.944  0.350  0.999  1.0
  Si  Si4  1  0.723  0.367  0.273  1.0
  Si  Si5  1  0.209  0.869  0.280  1.0
  Si  Si6  1  0.706  0.033  0.279  1.0
  Si  Si7  1  0.214  0.531  0.275  1.0
  Si  Si8  1  0.810  0.126  0.722  1.0
  Si  Si9  1  0.311  0.626  0.726  1.0
  Si  Si10  1  0.809  0.454  0.724  1.0
  Si  Si11  1  0.312  0.955  0.724  1.0
  O  O12  1  0.714  0.214  0.334  1.0
  O  O13  1  0.214  0.712  0.335  1.0
  O  O14  1  0.992  0.459  0.343  1.0
  O  O15  1  0.482  0.959  0.346  1.0
  O  O16  1  0.799  0.275  0.655  1.0
  O  O17  1  0.305  0.775  0.657  1.0
  O  O18  1  0.537  0.034  0.663  1.0
  O  O19  1  0.037  0.535  0.667  1.0
  O  O20  1  0.495  0.473  0.332  1.0
  O  O21  1  0.980  0.970  0.342  1.0
  O  O22  1  0.035  0.018  0.665  1.0
  O  O23  1  0.536  0.521  0.666  1.0
  O  O24  1  0.147  0.254  0.134  1.0
  O  O25  1  0.784  0.768  0.091  1.0
  O  O26  1  0.195  0.294  0.870  1.0
  O  O27  1  0.710  0.780  0.888  1.0
  O  O28  1  0.705  0.339  0.123  1.0
  O  O29  1  0.180  0.845  0.130  1.0
  O  O30  1  0.652  0.996  0.129  1.0
  O  O31  1  0.168  0.500  0.124  1.0
  O  O32  1  0.839  0.164  0.874  1.0
  O  O33  1  0.339  0.663  0.877  1.0
  O  O34  1  0.843  0.476  0.874  1.0
  O  O35  1  0.353  0.980  0.873  1.0
[/CIF]
.