Cr3(FeO4)2 is beta indium sulfide-derived structured and crystallizes in the trigonal R3m space group. Cr(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Cr(1)O6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3) and three equivalent O(4) atoms to form FeO4 tetrahedra that share corners with three equivalent Fe(2)O6 octahedra and corners with nine equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-59°. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra and edges with six equivalent Cr(1)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Cr(1) and one Fe(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to three equivalent Cr(1) atoms. In the third O site, O(3) is bonded to three equivalent Cr(1) and one Fe(1) atom to form a mixture of distorted corner and edge-sharing OCr3Fe trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Cr(1), one Fe(1), and one Fe(2) atom to form distorted OCr2Fe2 trigonal pyramids that share  a cornercorner with one O(3)Cr3Fe trigonal pyramid, corners with two equivalent O(4)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(3)Cr3Fe trigonal pyramid, and edges with two equivalent O(4)Cr2Fe2 trigonal pyramids.
Cr3(FeO4)2 is beta indium sulfide-derived structured and crystallizes in the trigonal R3m space group. Cr(1) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Cr(1)O6 octahedra. The Cr(1)-O(2) bond length is 1.95 Å. The Cr(1)-O(3) bond length is 2.08 Å. Both Cr(1)-O(1) bond lengths are 1.93 Å. Both Cr(1)-O(4) bond lengths are 2.09 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3) and three equivalent O(4) atoms to form FeO4 tetrahedra that share corners with three equivalent Fe(2)O6 octahedra and corners with nine equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-59°. The Fe(1)-O(3) bond length is 1.94 Å. All Fe(1)-O(4) bond lengths are 1.93 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with three equivalent Fe(1)O4 tetrahedra and edges with six equivalent Cr(1)O6 octahedra. All Fe(2)-O(1) bond lengths are 2.01 Å. All Fe(2)-O(4) bond lengths are 2.07 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Cr(1) and one Fe(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to three equivalent Cr(1) atoms. In the third O site, O(3) is bonded to three equivalent Cr(1) and one Fe(1) atom to form a mixture of distorted corner and edge-sharing OCr3Fe trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Cr(1), one Fe(1), and one Fe(2) atom to form distorted OCr2Fe2 trigonal pyramids that share  a cornercorner with one O(3)Cr3Fe trigonal pyramid, corners with two equivalent O(4)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(3)Cr3Fe trigonal pyramid, and edges with two equivalent O(4)Cr2Fe2 trigonal pyramids.