Fe2GeSe4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form FeSe6 octahedra that share corners with four equivalent Fe(1)Se6 octahedra, corners with four equivalent Fe(2)Se6 octahedra, corners with four equivalent Ge(1)Se4 trigonal pyramids, edges with two equivalent Fe(2)Se6 octahedra, and  an edgeedge with one Ge(1)Se4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 49-50°. In the second Fe site, Fe(2) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form FeSe6 octahedra that share corners with four equivalent Fe(1)Se6 octahedra, corners with two equivalent Ge(1)Se4 trigonal pyramids, edges with two equivalent Fe(1)Se6 octahedra, edges with two equivalent Fe(2)Se6 octahedra, and edges with two equivalent Ge(1)Se4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 49-50°. Ge(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form GeSe4 trigonal pyramids that share corners with two equivalent Fe(2)Se6 octahedra, corners with four equivalent Fe(1)Se6 octahedra,  an edgeedge with one Fe(1)Se6 octahedra, and edges with two equivalent Fe(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 64-74°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Ge(1) atom. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(2), and one Ge(1) atom. In the third Se site, Se(3) is bonded to one Fe(1), two equivalent Fe(2), and one Ge(1) atom to form corner-sharing SeFe3Ge tetrahedra.
Fe2GeSe4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form FeSe6 octahedra that share corners with four equivalent Fe(1)Se6 octahedra, corners with four equivalent Fe(2)Se6 octahedra, corners with four equivalent Ge(1)Se4 trigonal pyramids, edges with two equivalent Fe(2)Se6 octahedra, and  an edgeedge with one Ge(1)Se4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 49-50°. The Fe(1)-Se(2) bond length is 2.54 Å. The Fe(1)-Se(3) bond length is 2.53 Å. There are two shorter (2.58 Å) and two longer (2.73 Å) Fe(1)-Se(1) bond lengths. In the second Fe site, Fe(2) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form FeSe6 octahedra that share corners with four equivalent Fe(1)Se6 octahedra, corners with two equivalent Ge(1)Se4 trigonal pyramids, edges with two equivalent Fe(1)Se6 octahedra, edges with two equivalent Fe(2)Se6 octahedra, and edges with two equivalent Ge(1)Se4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 49-50°. Both Fe(2)-Se(1) bond lengths are 2.49 Å. Both Fe(2)-Se(2) bond lengths are 2.49 Å. Both Fe(2)-Se(3) bond lengths are 2.38 Å. Ge(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form GeSe4 trigonal pyramids that share corners with two equivalent Fe(2)Se6 octahedra, corners with four equivalent Fe(1)Se6 octahedra,  an edgeedge with one Fe(1)Se6 octahedra, and edges with two equivalent Fe(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 64-74°. The Ge(1)-Se(2) bond length is 2.45 Å. The Ge(1)-Se(3) bond length is 2.50 Å. Both Ge(1)-Se(1) bond lengths are 2.45 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Ge(1) atom. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Fe(1), two equivalent Fe(2), and one Ge(1) atom. In the third Se site, Se(3) is bonded to one Fe(1), two equivalent Fe(2), and one Ge(1) atom to form corner-sharing SeFe3Ge tetrahedra.