The material described by Mg6CuSi crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with ten Mg(1,1)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Si2 cuboctahedra; edges with four equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(1,1)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(2,2,2)Mg8Cu2Si2 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with ten Mg(1,1)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Si2 cuboctahedra; edges with four equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(1,1)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(2,2)Mg8Cu2Si2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with ten Mg(2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with two equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(2,2)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra. In the fourth Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with ten Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with two equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(2,2)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(2,2,2); and two equivalent Cu(1) atoms to form distorted MgMg10Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with six equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with eight Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(1,1)Mg8Cu2Si2 cuboctahedra; and faces with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2,2); and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with six equivalent Mg(4)Mg10Si2 cuboctahedra; corners with eight Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; and faces with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra. In the seventh Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with ten Mg(2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with two equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(2,2)Mg8Cu2Si2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Cu2Si2 cuboctahedra. Cu(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3); four Mg(1,1); and four Mg(2,2) atoms. Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(4); four Mg(1,1); and four Mg(2,2) atoms. is represented by the CIF file [CIF]
data_Mg6CuSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.028
_cell_length_b   6.028
_cell_length_c   4.851
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   118.215
_symmetry_Int_Tables_number   1
_cell_volume   155.353
_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
  Mg  Mg0  1  0.335  0.166  0.500  1.0
  Mg  Mg1  1  0.834  0.665  0.500  1.0
  Mg  Mg2  1  0.158  0.334  0.000  1.0
  Mg  Mg3  1  0.666  0.842  0.000  1.0
  Mg  Mg4  1  0.672  0.328  0.000  1.0
  Mg  Mg5  1  0.169  0.831  0.000  1.0
  Cu  Cu6  1  0.833  0.167  0.500  1.0
  Si  Si7  1  0.333  0.667  0.500  1.0
[/CIF]
.
The material described by Mg6CuSi crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with ten Mg(1,1)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Si2 cuboctahedra; edges with four equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(1,1)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(2,2,2)Mg8Cu2Si2 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with ten Mg(1,1)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with four equivalent Mg(4)Mg10Si2 cuboctahedra; edges with four equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(1,1)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(2,2)Mg8Cu2Si2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with ten Mg(2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with two equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(2,2)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra. In the fourth Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with ten Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with two equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(2,2)Mg8Cu2Si2 cuboctahedra; and faces with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(2,2,2); and two equivalent Cu(1) atoms to form distorted MgMg10Cu2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with six equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with eight Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(1,1)Mg8Cu2Si2 cuboctahedra; and faces with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(3); four equivalent Mg(1); four Mg(2,2,2); and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with six equivalent Mg(4)Mg10Si2 cuboctahedra; corners with eight Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra; edges with eight Mg(1,1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; and faces with four Mg(2,2,2)Mg8Cu2Si2 cuboctahedra. In the seventh Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cu(1), and two equivalent Si(1) atoms to form distorted MgMg8Cu2Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg10Cu2 cuboctahedra; corners with four equivalent Mg(4)Mg10Si2 cuboctahedra; corners with ten Mg(2,2)Mg8Cu2Si2 cuboctahedra; edges with two equivalent Mg(3)Mg10Cu2 cuboctahedra; edges with two equivalent Mg(4)Mg10Si2 cuboctahedra; edges with two equivalent Mg(2)Mg8Cu2Si2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cu2Si2 cuboctahedra; faces with two equivalent Mg(3)Mg10Cu2 cuboctahedra; faces with two equivalent Mg(4)Mg10Si2 cuboctahedra; faces with four Mg(2,2)Mg8Cu2Si2 cuboctahedra; and faces with eight equivalent Mg(1)Mg8Cu2Si2 cuboctahedra. Cu(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3); four Mg(1,1); and four Mg(2,2) atoms. Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(4); four Mg(1,1); and four Mg(2,2) atoms. is represented by the CIF file [CIF]
data_Mg6CuSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.028
_cell_length_b   6.028
_cell_length_c   4.851
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   118.215
_symmetry_Int_Tables_number   1
_cell_volume   155.353
_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
  Mg  Mg0  1  0.335  0.166  0.500  1.0
  Mg  Mg1  1  0.834  0.665  0.500  1.0
  Mg  Mg2  1  0.158  0.334  0.000  1.0
  Mg  Mg3  1  0.666  0.842  0.000  1.0
  Mg  Mg4  1  0.672  0.328  0.000  1.0
  Mg  Mg5  1  0.169  0.831  0.000  1.0
  Cu  Cu6  1  0.833  0.167  0.500  1.0
  Si  Si7  1  0.333  0.667  0.500  1.0
[/CIF]
.