Fe(SiO3)2 crystallizes in the monoclinic C2/c space group. Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Fe(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-59°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms.
Fe(SiO3)2 crystallizes in the monoclinic C2/c space group. Fe(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Fe(1)O6 octahedra. Both Fe(1)-O(2) bond lengths are 1.91 Å. There are two shorter (2.02 Å) and two longer (2.11 Å) Fe(1)-O(1) bond lengths. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-59°. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(2) bond length is 1.62 Å. Both Si(1)-O(3) bond lengths are 1.63 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Fe(1) and one Si(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms.