The crystal structure described by Mg6Si5 crystallizes in the triclinic P1 space group. There are twelve inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(3), one Si(7), and one Si(9) atom. In the second Mg site, Mg(2) is bonded in a 2-coordinate geometry to one Si(10), one Si(2), one Si(5), one Si(6), and two equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(2), one Si(3), one Si(7), two equivalent Si(10), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(4), one Si(5), and one Si(9) atom. In the fifth Mg site, Mg(5) is bonded in a 4-coordinate geometry to one Si(5), one Si(9), and two equivalent Si(8) atoms. In the sixth Mg site, Mg(6) is bonded in a 3-coordinate geometry to one Si(10) and two equivalent Si(3) atoms. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one Si(1), one Si(10), one Si(2), one Si(3), one Si(6), and one Si(7) atom. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(8), and two equivalent Si(5) atoms. In the ninth Mg site, Mg(9) is bonded in a 3-coordinate geometry to one Si(4), one Si(8), and one Si(9) atom. In the tenth Mg site, Mg(10) is bonded in a 3-coordinate geometry to one Si(6) and two equivalent Si(7) atoms. In the eleventh Mg site, Mg(11) is bonded in a distorted T-shaped geometry to one Si(3), one Si(7), and one Si(9) atom. In the twelfth Mg site, Mg(12) is bonded in a 2-coordinate geometry to one Si(8) and two equivalent Si(9) atoms. There are ten inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(4), one Mg(7), one Mg(8), two equivalent Mg(2), one Si(2), and one Si(4) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(7), one Mg(8), one Si(1), one Si(10), and one Si(5) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(11), one Mg(3), one Mg(7), two equivalent Mg(6), one Si(10), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 1-coordinate geometry to one Mg(4), one Mg(9), one Si(1), one Si(8), and one Si(9) atom. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), one Mg(5), two equivalent Mg(8), one Si(2), and one Si(8) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(10), one Mg(2), one Mg(7), two equivalent Mg(3), one Si(10), and one Si(7) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(11), one Mg(3), one Mg(7), two equivalent Mg(10), one Si(3), and one Si(6) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(12), one Mg(8), one Mg(9), two equivalent Mg(5), one Si(4), and one Si(5) atom. In the ninth Si site, Si(9) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(11), one Mg(4), one Mg(5), one Mg(9), two equivalent Mg(12), and one Si(4) atom. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(6), one Mg(7), two equivalent Mg(3), one Si(2), one Si(3), and one Si(6) atom. is represented by the CIF file [CIF]
data_Mg6Si5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.344
_cell_length_b   6.286
_cell_length_c   13.402
_cell_angle_alpha   95.745
_cell_angle_beta   101.352
_cell_angle_gamma   90.102
_symmetry_Int_Tables_number   1
_cell_volume   439.091
_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
  Mg  Mg0  1  0.319  0.205  0.985  1.0
  Mg  Mg1  1  0.166  0.209  0.511  1.0
  Mg  Mg2  1  0.835  0.633  0.673  1.0
  Mg  Mg3  1  0.127  0.924  0.313  1.0
  Mg  Mg4  1  0.281  0.521  0.192  1.0
  Mg  Mg5  1  0.659  0.914  0.866  1.0
  Mg  Mg6  1  0.708  0.135  0.649  1.0
  Mg  Mg7  1  0.615  0.464  0.427  1.0
  Mg  Mg8  1  0.872  0.202  0.079  1.0
  Mg  Mg9  1  0.671  0.427  0.875  1.0
  Mg  Mg10  1  0.184  0.681  0.953  1.0
  Mg  Mg11  1  0.732  0.723  0.093  1.0
  Si  Si12  1  0.625  0.032  0.431  1.0
  Si  Si13  1  0.949  0.792  0.503  1.0
  Si  Si14  1  0.122  0.968  0.797  1.0
  Si  Si15  1  0.652  0.085  0.256  1.0
  Si  Si16  1  0.111  0.532  0.386  1.0
  Si  Si17  1  0.367  0.466  0.680  1.0
  Si  Si18  1  0.122  0.354  0.798  1.0
  Si  Si19  1  0.781  0.453  0.240  1.0
  Si  Si20  1  0.288  0.937  0.132  1.0
  Si  Si21  1  0.313  0.841  0.654  1.0
[/CIF]
.
The crystal structure described by Mg6Si5 crystallizes in the triclinic P1 space group. There are twelve inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(3), one Si(7), and one Si(9) atom. In the second Mg site, Mg(2) is bonded in a 2-coordinate geometry to one Si(10), one Si(2), one Si(5), one Si(6), and two equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(2), one Si(3), one Si(7), two equivalent Si(10), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(4), one Si(5), and one Si(9) atom. In the fifth Mg site, Mg(5) is bonded in a 4-coordinate geometry to one Si(5), one Si(9), and two equivalent Si(8) atoms. In the sixth Mg site, Mg(6) is bonded in a 3-coordinate geometry to one Si(10) and two equivalent Si(3) atoms. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one Si(1), one Si(10), one Si(2), one Si(3), one Si(6), and one Si(7) atom. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(8), and two equivalent Si(5) atoms. In the ninth Mg site, Mg(9) is bonded in a 3-coordinate geometry to one Si(4), one Si(8), and one Si(9) atom. In the tenth Mg site, Mg(10) is bonded in a 3-coordinate geometry to one Si(6) and two equivalent Si(7) atoms. In the eleventh Mg site, Mg(11) is bonded in a distorted T-shaped geometry to one Si(3), one Si(7), and one Si(9) atom. In the twelfth Mg site, Mg(12) is bonded in a 2-coordinate geometry to one Si(8) and two equivalent Si(9) atoms. There are ten inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(4), one Mg(7), one Mg(8), two equivalent Mg(2), one Si(2), and one Si(4) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(7), one Mg(8), one Si(1), one Si(10), and one Si(5) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(11), one Mg(3), one Mg(7), two equivalent Mg(6), one Si(10), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 1-coordinate geometry to one Mg(4), one Mg(9), one Si(1), one Si(8), and one Si(9) atom. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), one Mg(5), two equivalent Mg(8), one Si(2), and one Si(8) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(10), one Mg(2), one Mg(7), two equivalent Mg(3), one Si(10), and one Si(7) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(11), one Mg(3), one Mg(7), two equivalent Mg(10), one Si(3), and one Si(6) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(12), one Mg(8), one Mg(9), two equivalent Mg(5), one Si(4), and one Si(5) atom. In the ninth Si site, Si(9) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(11), one Mg(4), one Mg(5), one Mg(9), two equivalent Mg(12), and one Si(4) atom. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(6), one Mg(7), two equivalent Mg(3), one Si(2), one Si(3), and one Si(6) atom. is represented by the CIF file [CIF]
data_Mg6Si5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.344
_cell_length_b   6.286
_cell_length_c   13.402
_cell_angle_alpha   95.745
_cell_angle_beta   101.352
_cell_angle_gamma   90.102
_symmetry_Int_Tables_number   1
_cell_volume   439.091
_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
  Mg  Mg0  1  0.319  0.205  0.985  1.0
  Mg  Mg1  1  0.166  0.209  0.511  1.0
  Mg  Mg2  1  0.835  0.633  0.673  1.0
  Mg  Mg3  1  0.127  0.924  0.313  1.0
  Mg  Mg4  1  0.281  0.521  0.192  1.0
  Mg  Mg5  1  0.659  0.914  0.866  1.0
  Mg  Mg6  1  0.708  0.135  0.649  1.0
  Mg  Mg7  1  0.615  0.464  0.427  1.0
  Mg  Mg8  1  0.872  0.202  0.079  1.0
  Mg  Mg9  1  0.671  0.427  0.875  1.0
  Mg  Mg10  1  0.184  0.681  0.953  1.0
  Mg  Mg11  1  0.732  0.723  0.093  1.0
  Si  Si12  1  0.625  0.032  0.431  1.0
  Si  Si13  1  0.949  0.792  0.503  1.0
  Si  Si14  1  0.122  0.968  0.797  1.0
  Si  Si15  1  0.652  0.085  0.256  1.0
  Si  Si16  1  0.111  0.532  0.386  1.0
  Si  Si17  1  0.367  0.466  0.680  1.0
  Si  Si18  1  0.122  0.354  0.798  1.0
  Si  Si19  1  0.781  0.453  0.240  1.0
  Si  Si20  1  0.288  0.937  0.132  1.0
  Si  Si21  1  0.313  0.841  0.654  1.0
[/CIF]
.