FeGa2Se4 crystallizes in the tetragonal P-42m space group. Fe(1) is bonded to four equivalent Se(1) atoms to form FeSe4 tetrahedra that share corners with eight equivalent Ga(1)Se4 tetrahedra. Ga(1) is bonded to four equivalent Se(1) atoms to form GaSe4 tetrahedra that share corners with four equivalent Fe(1)Se4 tetrahedra and corners with four equivalent Ga(1)Se4 tetrahedra. Se(1) is bonded in a trigonal non-coplanar geometry to one Fe(1) and two equivalent Ga(1) atoms.
FeGa2Se4 crystallizes in the tetragonal P-42m space group. Fe(1) is bonded to four equivalent Se(1) atoms to form FeSe4 tetrahedra that share corners with eight equivalent Ga(1)Se4 tetrahedra. All Fe(1)-Se(1) bond lengths are 2.44 Å. Ga(1) is bonded to four equivalent Se(1) atoms to form GaSe4 tetrahedra that share corners with four equivalent Fe(1)Se4 tetrahedra and corners with four equivalent Ga(1)Se4 tetrahedra. All Ga(1)-Se(1) bond lengths are 2.47 Å. Se(1) is bonded in a trigonal non-coplanar geometry to one Fe(1) and two equivalent Ga(1) atoms.