The structure described by Mg3Si4 crystallizes in the triclinic P1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Si(3), one Si(4), and one Si(8) atom. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to one Mg(5) and one Si(3) atom. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Mg(5), one Si(1), one Si(3), and one Si(5) atom. In the fourth Mg site, Mg(4) is bonded in a distorted single-bond geometry to one Mg(5), one Mg(6), one Si(6), one Si(7), and two equivalent Si(2) atoms. In the fifth Mg site, Mg(5) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Si(5), two equivalent Si(1), and two equivalent Si(6) atoms. In the sixth Mg site, Mg(6) is bonded in a 5-coordinate geometry to one Mg(4), one Si(2), one Si(8), and two equivalent Si(7) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted single-bond geometry to one Mg(3) and two equivalent Mg(5) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(6), two equivalent Mg(4), one Si(4), one Si(6), one Si(7), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 3-coordinate geometry to one Mg(1), one Si(2), and one Si(3) atom. In the fifth Si site, Si(5) is bonded in a 3-coordinate geometry to one Mg(3), one Mg(5), and one Si(7) atom. In the sixth Si site, Si(6) is bonded in a 1-coordinate geometry to one Mg(4), two equivalent Mg(5), and one Si(2) atom. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(6), one Si(2), one Si(5), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 1-coordinate geometry to one Mg(1), one Mg(6), one Si(2), and one Si(7) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.280
_cell_length_b   7.155
_cell_length_c   8.087
_cell_angle_alpha   115.607
_cell_angle_beta   95.106
_cell_angle_gamma   106.018
_symmetry_Int_Tables_number   1
_cell_volume   257.079
_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  0.466  0.200  0.255  1.0
  Mg  Mg1  1  0.049  0.120  0.034  1.0
  Mg  Mg2  1  0.907  0.657  0.401  1.0
  Mg  Mg3  1  0.748  0.359  0.804  1.0
  Mg  Mg4  1  0.770  0.964  0.652  1.0
  Mg  Mg5  1  0.993  0.682  0.991  1.0
  Si  Si6  1  0.233  0.831  0.583  1.0
  Si  Si7  1  0.344  0.537  0.745  1.0
  Si  Si8  1  0.996  0.331  0.279  1.0
  Si  Si9  1  0.208  0.399  0.496  1.0
  Si  Si10  1  0.520  0.776  0.310  1.0
  Si  Si11  1  0.347  0.137  0.661  1.0
  Si  Si12  1  0.454  0.575  0.009  1.0
  Si  Si13  1  0.458  0.932  0.034  1.0
[/CIF]
.
The structure described by Mg3Si4 crystallizes in the triclinic P1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Si(3), one Si(4), and one Si(8) atom. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to one Mg(5) and one Si(3) atom. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Mg(5), one Si(1), one Si(3), and one Si(5) atom. In the fourth Mg site, Mg(4) is bonded in a distorted single-bond geometry to one Mg(5), one Mg(6), one Si(6), one Si(7), and two equivalent Si(2) atoms. In the fifth Mg site, Mg(5) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Si(5), two equivalent Si(1), and two equivalent Si(6) atoms. In the sixth Mg site, Mg(6) is bonded in a 5-coordinate geometry to one Mg(4), one Si(2), one Si(8), and two equivalent Si(7) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted single-bond geometry to one Mg(3) and two equivalent Mg(5) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(6), two equivalent Mg(4), one Si(4), one Si(6), one Si(7), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 3-coordinate geometry to one Mg(1), one Si(2), and one Si(3) atom. In the fifth Si site, Si(5) is bonded in a 3-coordinate geometry to one Mg(3), one Mg(5), and one Si(7) atom. In the sixth Si site, Si(6) is bonded in a 1-coordinate geometry to one Mg(4), two equivalent Mg(5), and one Si(2) atom. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(6), one Si(2), one Si(5), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 1-coordinate geometry to one Mg(1), one Mg(6), one Si(2), and one Si(7) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.280
_cell_length_b   7.155
_cell_length_c   8.087
_cell_angle_alpha   115.607
_cell_angle_beta   95.106
_cell_angle_gamma   106.018
_symmetry_Int_Tables_number   1
_cell_volume   257.079
_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  0.466  0.200  0.255  1.0
  Mg  Mg1  1  0.049  0.120  0.034  1.0
  Mg  Mg2  1  0.907  0.657  0.401  1.0
  Mg  Mg3  1  0.748  0.359  0.804  1.0
  Mg  Mg4  1  0.770  0.964  0.652  1.0
  Mg  Mg5  1  0.993  0.682  0.991  1.0
  Si  Si6  1  0.233  0.831  0.583  1.0
  Si  Si7  1  0.344  0.537  0.745  1.0
  Si  Si8  1  0.996  0.331  0.279  1.0
  Si  Si9  1  0.208  0.399  0.496  1.0
  Si  Si10  1  0.520  0.776  0.310  1.0
  Si  Si11  1  0.347  0.137  0.661  1.0
  Si  Si12  1  0.454  0.575  0.009  1.0
  Si  Si13  1  0.458  0.932  0.034  1.0
[/CIF]
.