Mg2Mn3AlS8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. Mg(1) is bonded to one S(1) and three equivalent S(2) atoms to form MgS4 tetrahedra that share corners with three equivalent Al(1)S6 octahedra and corners with nine equivalent Mn(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 58-59°. Mn(1) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form MnS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Al(1)S6 octahedra, and edges with four equivalent Mn(1)S6 octahedra. Al(1) is bonded to six equivalent S(2) atoms to form AlS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra and edges with six equivalent Mn(1)S6 octahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1) and three equivalent Mn(1) atoms to form distorted SMgMn3 trigonal pyramids that share corners with three equivalent S(1)MgMn3 trigonal pyramids, corners with nine equivalent S(2)MgMn2Al trigonal pyramids, and edges with three equivalent S(2)MgMn2Al trigonal pyramids. In the second S site, S(2) is bonded to one Mg(1), two equivalent Mn(1), and one Al(1) atom to form distorted SMgMn2Al trigonal pyramids that share corners with three equivalent S(1)MgMn3 trigonal pyramids, corners with nine equivalent S(2)MgMn2Al trigonal pyramids,  an edgeedge with one S(1)MgMn3 trigonal pyramid, and edges with two equivalent S(2)MgMn2Al trigonal pyramids.
Mg2Mn3AlS8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. Mg(1) is bonded to one S(1) and three equivalent S(2) atoms to form MgS4 tetrahedra that share corners with three equivalent Al(1)S6 octahedra and corners with nine equivalent Mn(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 58-59°. The Mg(1)-S(1) bond length is 2.42 Å. All Mg(1)-S(2) bond lengths are 2.45 Å. Mn(1) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form MnS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Al(1)S6 octahedra, and edges with four equivalent Mn(1)S6 octahedra. Both Mn(1)-S(1) bond lengths are 2.46 Å. All Mn(1)-S(2) bond lengths are 2.46 Å. Al(1) is bonded to six equivalent S(2) atoms to form AlS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra and edges with six equivalent Mn(1)S6 octahedra. All Al(1)-S(2) bond lengths are 2.43 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1) and three equivalent Mn(1) atoms to form distorted SMgMn3 trigonal pyramids that share corners with three equivalent S(1)MgMn3 trigonal pyramids, corners with nine equivalent S(2)MgMn2Al trigonal pyramids, and edges with three equivalent S(2)MgMn2Al trigonal pyramids. In the second S site, S(2) is bonded to one Mg(1), two equivalent Mn(1), and one Al(1) atom to form distorted SMgMn2Al trigonal pyramids that share corners with three equivalent S(1)MgMn3 trigonal pyramids, corners with nine equivalent S(2)MgMn2Al trigonal pyramids,  an edgeedge with one S(1)MgMn3 trigonal pyramid, and edges with two equivalent S(2)MgMn2Al trigonal pyramids.