The crystal structure described by Mg2AsO5 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent As(1)O4 tetrahedra, corners with four equivalent Mg(2)O5 trigonal bipyramids, and edges with two equivalent Mg(1)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 50-65°. As(1) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form AsO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra and corners with four equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-65°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(2) and two equivalent Mg(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Mg(2) and one As(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one As(1) atom. is represented by the CIF card [CIF]
data_Mg2AsO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.170
_cell_length_b   8.421
_cell_length_c   8.462
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   439.663
_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  0.253  0.500  0.500  1.0
  Mg  Mg1  1  0.247  0.000  0.000  1.0
  Mg  Mg2  1  0.747  0.500  0.500  1.0
  Mg  Mg3  1  0.753  0.000  0.000  1.0
  Mg  Mg4  1  0.500  0.871  0.356  1.0
  Mg  Mg5  1  0.500  0.129  0.644  1.0
  Mg  Mg6  1  0.000  0.629  0.856  1.0
  Mg  Mg7  1  0.000  0.371  0.144  1.0
  As  As8  1  0.000  0.752  0.244  1.0
  As  As9  1  0.000  0.248  0.756  1.0
  As  As10  1  0.500  0.748  0.744  1.0
  As  As11  1  0.500  0.252  0.256  1.0
  O  O12  1  0.000  0.643  0.417  1.0
  O  O13  1  0.000  0.357  0.583  1.0
  O  O14  1  0.500  0.857  0.917  1.0
  O  O15  1  0.500  0.143  0.083  1.0
  O  O16  1  0.500  0.641  0.416  1.0
  O  O17  1  0.500  0.359  0.584  1.0
  O  O18  1  0.000  0.859  0.916  1.0
  O  O19  1  0.000  0.141  0.084  1.0
  O  O20  1  0.000  0.611  0.098  1.0
  O  O21  1  0.000  0.389  0.902  1.0
  O  O22  1  0.500  0.889  0.598  1.0
  O  O23  1  0.500  0.111  0.402  1.0
  O  O24  1  0.225  0.870  0.223  1.0
  O  O25  1  0.225  0.130  0.777  1.0
  O  O26  1  0.275  0.630  0.723  1.0
  O  O27  1  0.275  0.370  0.277  1.0
  O  O28  1  0.775  0.130  0.777  1.0
  O  O29  1  0.775  0.870  0.223  1.0
  O  O30  1  0.725  0.370  0.277  1.0
  O  O31  1  0.725  0.630  0.723  1.0
[/CIF]
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The crystal structure described by Mg2AsO5 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with four equivalent As(1)O4 tetrahedra, corners with four equivalent Mg(2)O5 trigonal bipyramids, and edges with two equivalent Mg(1)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Mg(1)O6 octahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 50-65°. As(1) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form AsO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra and corners with four equivalent Mg(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-65°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(2) and two equivalent Mg(1) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Mg(2) and one As(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one As(1) atom. is represented by the CIF card [CIF]
data_Mg2AsO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.170
_cell_length_b   8.421
_cell_length_c   8.462
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   439.663
_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  0.253  0.500  0.500  1.0
  Mg  Mg1  1  0.247  0.000  0.000  1.0
  Mg  Mg2  1  0.747  0.500  0.500  1.0
  Mg  Mg3  1  0.753  0.000  0.000  1.0
  Mg  Mg4  1  0.500  0.871  0.356  1.0
  Mg  Mg5  1  0.500  0.129  0.644  1.0
  Mg  Mg6  1  0.000  0.629  0.856  1.0
  Mg  Mg7  1  0.000  0.371  0.144  1.0
  As  As8  1  0.000  0.752  0.244  1.0
  As  As9  1  0.000  0.248  0.756  1.0
  As  As10  1  0.500  0.748  0.744  1.0
  As  As11  1  0.500  0.252  0.256  1.0
  O  O12  1  0.000  0.643  0.417  1.0
  O  O13  1  0.000  0.357  0.583  1.0
  O  O14  1  0.500  0.857  0.917  1.0
  O  O15  1  0.500  0.143  0.083  1.0
  O  O16  1  0.500  0.641  0.416  1.0
  O  O17  1  0.500  0.359  0.584  1.0
  O  O18  1  0.000  0.859  0.916  1.0
  O  O19  1  0.000  0.141  0.084  1.0
  O  O20  1  0.000  0.611  0.098  1.0
  O  O21  1  0.000  0.389  0.902  1.0
  O  O22  1  0.500  0.889  0.598  1.0
  O  O23  1  0.500  0.111  0.402  1.0
  O  O24  1  0.225  0.870  0.223  1.0
  O  O25  1  0.225  0.130  0.777  1.0
  O  O26  1  0.275  0.630  0.723  1.0
  O  O27  1  0.275  0.370  0.277  1.0
  O  O28  1  0.775  0.130  0.777  1.0
  O  O29  1  0.775  0.870  0.223  1.0
  O  O30  1  0.725  0.370  0.277  1.0
  O  O31  1  0.725  0.630  0.723  1.0
[/CIF]
.