Fe2SiO4 crystallizes in the orthorhombic Imma space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with six equivalent Si(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-14°. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted FeO6 octahedra that share edges with two equivalent Fe(2)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with four equivalent Si(1)O6 octahedra. Si(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form SiO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-14°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(2), and one Si(1) atom. In the second O site, O(2) is bonded to one Fe(2), two equivalent Fe(1), and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing OFe3Si2 square pyramids.
Fe2SiO4 crystallizes in the orthorhombic Imma space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with six equivalent Si(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-14°. Both Fe(1)-O(1) bond lengths are 2.05 Å. All Fe(1)-O(2) bond lengths are 2.45 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted FeO6 octahedra that share edges with two equivalent Fe(2)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with four equivalent Si(1)O6 octahedra. Both Fe(2)-O(2) bond lengths are 2.04 Å. All Fe(2)-O(1) bond lengths are 2.11 Å. Si(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form SiO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-14°. Both Si(1)-O(1) bond lengths are 1.79 Å. All Si(1)-O(2) bond lengths are 1.88 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(2), and one Si(1) atom. In the second O site, O(2) is bonded to one Fe(2), two equivalent Fe(1), and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing OFe3Si2 square pyramids.