CaFeSiO5 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. In the second Fe site, Fe(2) 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 two equivalent Fe(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. 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 two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-54°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Fe(1), and one Fe(2) atom.
CaFeSiO5 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(3), one O(4), one O(5), two equivalent O(1), and two equivalent O(2) atoms. The Ca(1)-O(3) bond length is 2.43 Å. The Ca(1)-O(4) bond length is 2.42 Å. The Ca(1)-O(5) bond length is 2.31 Å. There is one shorter (2.43 Å) and one longer (2.56 Å) Ca(1)-O(1) bond length. There is one shorter (2.44 Å) and one longer (2.57 Å) Ca(1)-O(2) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. Both Fe(1)-O(2) bond lengths are 2.06 Å. Both Fe(1)-O(3) bond lengths are 2.01 Å. Both Fe(1)-O(5) bond lengths are 1.85 Å. In the second Fe site, Fe(2) 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 two equivalent Fe(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. Both Fe(2)-O(1) bond lengths are 2.07 Å. Both Fe(2)-O(4) bond lengths are 1.99 Å. Both Fe(2)-O(5) bond lengths are 1.85 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 two equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-54°. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.66 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Fe(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Fe(1), and one Fe(2) atom.