Mn2Si2O7 crystallizes in the orthorhombic Ama2 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(2)O5 square pyramids. In the second Mn site, Mn(2) is bonded to one O(2), two equivalent O(1), and two equivalent O(4) atoms to form MnO5 square pyramids that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Mn(2)O5 square pyramids, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-54°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mn(2) and two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mn(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one Si(1) atom.
Mn2Si2O7 crystallizes in the orthorhombic Ama2 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(2)O5 square pyramids. Both Mn(1)-O(1) bond lengths are 2.18 Å. Both Mn(1)-O(3) bond lengths are 1.86 Å. Both Mn(1)-O(4) bond lengths are 2.18 Å. In the second Mn site, Mn(2) is bonded to one O(2), two equivalent O(1), and two equivalent O(4) atoms to form MnO5 square pyramids that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(1)O6 octahedra. The Mn(2)-O(2) bond length is 2.26 Å. Both Mn(2)-O(1) bond lengths are 1.94 Å. Both Mn(2)-O(4) bond lengths are 1.94 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Mn(2)O5 square pyramids, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-54°. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(2) bond length is 1.69 Å. The Si(1)-O(3) bond length is 1.59 Å. The Si(1)-O(4) bond length is 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mn(2) and two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mn(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one Si(1) atom.