Fe2SiO4 is Ilmenite-like structured and crystallizes in the triclinic P-1 space group. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with four equivalent Fe(6)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-67°. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with four equivalent Fe(5)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Fe(4)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-63°. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with four equivalent Fe(6)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-63°. In the fourth Fe site, Fe(4) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with four equivalent Fe(5)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-67°. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(6)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-67°. In the sixth Fe site, Fe(6) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-67°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one Fe(5)O6 octahedra, corners with three equivalent Fe(6)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-62°. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra,  a cornercorner with one Fe(6)O6 octahedra, corners with three equivalent Fe(5)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, and  an edgeedge with one Fe(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-62°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(3), one Fe(6), and one Si(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(4), one Fe(5), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Fe(2), one Fe(4), one Fe(6), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Fe(1), one Fe(3), one Fe(5), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(5), one Fe(6), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), one Fe(5), one Fe(6), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Fe(3), one Fe(5), one Fe(6), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Fe(4), one Fe(5), one Fe(6), and one Si(2) atom.
Fe2SiO4 is Ilmenite-like structured and crystallizes in the triclinic P-1 space group. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with four equivalent Fe(6)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(3)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-67°. Both Fe(1)-O(1) bond lengths are 2.13 Å. Both Fe(1)-O(4) bond lengths are 2.15 Å. Both Fe(1)-O(5) bond lengths are 2.27 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with four equivalent Fe(5)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Fe(4)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-63°. Both Fe(2)-O(2) bond lengths are 2.19 Å. Both Fe(2)-O(3) bond lengths are 2.20 Å. Both Fe(2)-O(6) bond lengths are 2.17 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with four equivalent Fe(6)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(5)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-63°. Both Fe(3)-O(1) bond lengths are 2.18 Å. Both Fe(3)-O(4) bond lengths are 2.20 Å. Both Fe(3)-O(7) bond lengths are 2.18 Å. In the fourth Fe site, Fe(4) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with four equivalent Fe(5)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-67°. Both Fe(4)-O(2) bond lengths are 2.14 Å. Both Fe(4)-O(3) bond lengths are 2.15 Å. Both Fe(4)-O(8) bond lengths are 2.26 Å. In the fifth Fe site, Fe(5) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with four equivalent Fe(6)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-67°. The Fe(5)-O(2) bond length is 2.13 Å. The Fe(5)-O(4) bond length is 2.24 Å. The Fe(5)-O(5) bond length is 2.29 Å. The Fe(5)-O(6) bond length is 2.12 Å. The Fe(5)-O(7) bond length is 2.35 Å. The Fe(5)-O(8) bond length is 2.10 Å. In the sixth Fe site, Fe(6) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with four equivalent Fe(5)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-67°. The Fe(6)-O(1) bond length is 2.13 Å. The Fe(6)-O(3) bond length is 2.24 Å. The Fe(6)-O(5) bond length is 2.10 Å. The Fe(6)-O(6) bond length is 2.36 Å. The Fe(6)-O(7) bond length is 2.12 Å. The Fe(6)-O(8) bond length is 2.29 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one Fe(5)O6 octahedra, corners with three equivalent Fe(6)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Fe(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-62°. The Si(1)-O(1) bond length is 1.67 Å. The Si(1)-O(4) bond length is 1.64 Å. The Si(1)-O(5) bond length is 1.66 Å. The Si(1)-O(7) bond length is 1.66 Å. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra,  a cornercorner with one Fe(6)O6 octahedra, corners with three equivalent Fe(5)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, and  an edgeedge with one Fe(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-62°. The Si(2)-O(2) bond length is 1.67 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(6) bond length is 1.66 Å. The Si(2)-O(8) bond length is 1.66 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(3), one Fe(6), and one Si(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(4), one Fe(5), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Fe(2), one Fe(4), one Fe(6), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Fe(1), one Fe(3), one Fe(5), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(5), one Fe(6), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), one Fe(5), one Fe(6), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Fe(3), one Fe(5), one Fe(6), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Fe(4), one Fe(5), one Fe(6), and one Si(2) atom.