MgCrGaS4 is Spinel-derived structured and crystallizes in the orthorhombic Imma space group. Mg(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form MgS4 tetrahedra that share corners with six equivalent Cr(1)S6 octahedra and corners with six equivalent Ga(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 57-60°. Cr(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form CrS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Cr(1)S6 octahedra, and edges with four equivalent Ga(1)S6 octahedra. Ga(1) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form GaS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ga(1)S6 octahedra, and edges with four equivalent Cr(1)S6 octahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), two equivalent Cr(1), and one Ga(1) atom to form distorted SMgCr2Ga trigonal pyramids that share corners with six equivalent S(1)MgCr2Ga trigonal pyramids, corners with six equivalent S(2)MgCrGa2 trigonal pyramids,  an edgeedge with one S(1)MgCr2Ga trigonal pyramid, and edges with two equivalent S(2)MgCrGa2 trigonal pyramids. In the second S site, S(2) is bonded to one Mg(1), one Cr(1), and two equivalent Ga(1) atoms to form distorted SMgCrGa2 trigonal pyramids that share corners with six equivalent S(1)MgCr2Ga trigonal pyramids, corners with six equivalent S(2)MgCrGa2 trigonal pyramids,  an edgeedge with one S(2)MgCrGa2 trigonal pyramid, and edges with two equivalent S(1)MgCr2Ga trigonal pyramids.
MgCrGaS4 is Spinel-derived structured and crystallizes in the orthorhombic Imma space group. Mg(1) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form MgS4 tetrahedra that share corners with six equivalent Cr(1)S6 octahedra and corners with six equivalent Ga(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 57-60°. Both Mg(1)-S(1) bond lengths are 2.46 Å. Both Mg(1)-S(2) bond lengths are 2.44 Å. Cr(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form CrS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Cr(1)S6 octahedra, and edges with four equivalent Ga(1)S6 octahedra. Both Cr(1)-S(2) bond lengths are 2.42 Å. All Cr(1)-S(1) bond lengths are 2.43 Å. Ga(1) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form GaS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ga(1)S6 octahedra, and edges with four equivalent Cr(1)S6 octahedra. Both Ga(1)-S(1) bond lengths are 2.49 Å. All Ga(1)-S(2) bond lengths are 2.47 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), two equivalent Cr(1), and one Ga(1) atom to form distorted SMgCr2Ga trigonal pyramids that share corners with six equivalent S(1)MgCr2Ga trigonal pyramids, corners with six equivalent S(2)MgCrGa2 trigonal pyramids,  an edgeedge with one S(1)MgCr2Ga trigonal pyramid, and edges with two equivalent S(2)MgCrGa2 trigonal pyramids. In the second S site, S(2) is bonded to one Mg(1), one Cr(1), and two equivalent Ga(1) atoms to form distorted SMgCrGa2 trigonal pyramids that share corners with six equivalent S(1)MgCr2Ga trigonal pyramids, corners with six equivalent S(2)MgCrGa2 trigonal pyramids,  an edgeedge with one S(2)MgCrGa2 trigonal pyramid, and edges with two equivalent S(1)MgCr2Ga trigonal pyramids.