The structure described by Mg3Si2 crystallizes in the triclinic P-1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to two equivalent Si(1) and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(3), two equivalent Si(1), and three equivalent Si(2) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(4), and two equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to two equivalent Si(3) and three equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded in a 3-coordinate geometry to one Si(1), one Si(4), and two equivalent Si(3) atoms. In the sixth Mg site, Mg(6) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(3), and one Si(4) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), two equivalent Mg(1), two equivalent Mg(2), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(6), three equivalent Mg(1), three equivalent Mg(2), and one Si(2) atom. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), one Si(1), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), three equivalent Mg(4), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Si2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.354
_cell_length_b   5.537
_cell_length_c   13.351
_cell_angle_alpha   101.487
_cell_angle_beta   97.507
_cell_angle_gamma   92.213
_symmetry_Int_Tables_number   1
_cell_volume   383.639
_cell_formula_units_Z   4
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  0.444  0.264  0.045  1.0
  Mg  Mg1  1  0.556  0.736  0.955  1.0
  Mg  Mg2  1  0.027  0.663  0.112  1.0
  Mg  Mg3  1  0.973  0.337  0.888  1.0
  Mg  Mg4  1  0.205  0.599  0.730  1.0
  Mg  Mg5  1  0.795  0.401  0.270  1.0
  Mg  Mg6  1  0.848  0.738  0.509  1.0
  Mg  Mg7  1  0.152  0.262  0.491  1.0
  Mg  Mg8  1  0.666  0.293  0.641  1.0
  Mg  Mg9  1  0.334  0.707  0.359  1.0
  Mg  Mg10  1  0.268  0.146  0.250  1.0
  Mg  Mg11  1  0.732  0.854  0.750  1.0
  Si  Si12  1  0.541  0.742  0.171  1.0
  Si  Si13  1  0.459  0.258  0.829  1.0
  Si  Si14  1  0.941  0.152  0.070  1.0
  Si  Si15  1  0.059  0.848  0.930  1.0
  Si  Si16  1  0.151  0.078  0.676  1.0
  Si  Si17  1  0.849  0.922  0.324  1.0
  Si  Si18  1  0.376  0.758  0.570  1.0
  Si  Si19  1  0.624  0.242  0.430  1.0
[/CIF]
.
The structure described by Mg3Si2 crystallizes in the triclinic P-1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to two equivalent Si(1) and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(3), two equivalent Si(1), and three equivalent Si(2) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(4), and two equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to two equivalent Si(3) and three equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded in a 3-coordinate geometry to one Si(1), one Si(4), and two equivalent Si(3) atoms. In the sixth Mg site, Mg(6) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(3), and one Si(4) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), two equivalent Mg(1), two equivalent Mg(2), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(6), three equivalent Mg(1), three equivalent Mg(2), and one Si(2) atom. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), one Si(1), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), three equivalent Mg(4), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Si2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.354
_cell_length_b   5.537
_cell_length_c   13.351
_cell_angle_alpha   101.487
_cell_angle_beta   97.507
_cell_angle_gamma   92.213
_symmetry_Int_Tables_number   1
_cell_volume   383.639
_cell_formula_units_Z   4
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  0.444  0.264  0.045  1.0
  Mg  Mg1  1  0.556  0.736  0.955  1.0
  Mg  Mg2  1  0.027  0.663  0.112  1.0
  Mg  Mg3  1  0.973  0.337  0.888  1.0
  Mg  Mg4  1  0.205  0.599  0.730  1.0
  Mg  Mg5  1  0.795  0.401  0.270  1.0
  Mg  Mg6  1  0.848  0.738  0.509  1.0
  Mg  Mg7  1  0.152  0.262  0.491  1.0
  Mg  Mg8  1  0.666  0.293  0.641  1.0
  Mg  Mg9  1  0.334  0.707  0.359  1.0
  Mg  Mg10  1  0.268  0.146  0.250  1.0
  Mg  Mg11  1  0.732  0.854  0.750  1.0
  Si  Si12  1  0.541  0.742  0.171  1.0
  Si  Si13  1  0.459  0.258  0.829  1.0
  Si  Si14  1  0.941  0.152  0.070  1.0
  Si  Si15  1  0.059  0.848  0.930  1.0
  Si  Si16  1  0.151  0.078  0.676  1.0
  Si  Si17  1  0.849  0.922  0.324  1.0
  Si  Si18  1  0.376  0.758  0.570  1.0
  Si  Si19  1  0.624  0.242  0.430  1.0
[/CIF]
.