CaFe3O7 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CaO7 pentagonal bipyramids that share  a cornercorner with one Fe(2)O5 trigonal bipyramid, corners with six equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Fe(1)O5 trigonal bipyramids, and edges with two equivalent Fe(2)O5 trigonal bipyramids. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted FeO5 trigonal bipyramids that share corners with three equivalent Ca(1)O7 pentagonal bipyramids, corners with two equivalent Fe(2)O5 trigonal bipyramids,  an edgeedge with one Ca(1)O7 pentagonal bipyramid,  an edgeedge with one Fe(2)O5 trigonal bipyramid, and edges with two equivalent Fe(1)O5 trigonal bipyramids. In the second Fe site, Fe(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Ca(1)O7 pentagonal bipyramid, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Ca(1)O7 pentagonal bipyramids, and edges with two equivalent Fe(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one Fe(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Ca(1) and one Fe(1) atom. In the third O site, O(1) is bonded to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms to form a mixture of distorted edge and corner-sharing OCaFe3 tetrahedra. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms.
CaFe3O7 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to one O(3), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CaO7 pentagonal bipyramids that share  a cornercorner with one Fe(2)O5 trigonal bipyramid, corners with six equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Fe(1)O5 trigonal bipyramids, and edges with two equivalent Fe(2)O5 trigonal bipyramids. The Ca(1)-O(3) bond length is 2.32 Å. Both Ca(1)-O(1) bond lengths are 2.49 Å. Both Ca(1)-O(2) bond lengths are 2.50 Å. Both Ca(1)-O(4) bond lengths are 2.30 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted FeO5 trigonal bipyramids that share corners with three equivalent Ca(1)O7 pentagonal bipyramids, corners with two equivalent Fe(2)O5 trigonal bipyramids,  an edgeedge with one Ca(1)O7 pentagonal bipyramid,  an edgeedge with one Fe(2)O5 trigonal bipyramid, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The Fe(1)-O(4) bond length is 1.78 Å. There is one shorter (1.97 Å) and one longer (2.02 Å) Fe(1)-O(1) bond length. There is one shorter (1.98 Å) and one longer (2.01 Å) Fe(1)-O(2) bond length. In the second Fe site, Fe(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Ca(1)O7 pentagonal bipyramid, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with two equivalent Ca(1)O7 pentagonal bipyramids, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The Fe(2)-O(3) bond length is 1.79 Å. Both Fe(2)-O(1) bond lengths are 2.00 Å. Both Fe(2)-O(2) bond lengths are 2.00 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one Fe(2) atom. In the second O site, O(4) is bonded in a bent 150 degrees geometry to one Ca(1) and one Fe(1) atom. In the third O site, O(1) is bonded to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms to form a mixture of distorted edge and corner-sharing OCaFe3 tetrahedra. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms.