Mg2Zn crystallizes in the trigonal P-3m1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Mg(2) and three equivalent Zn(1) atoms to form distorted MgMg3Zn3 cuboctahedra that share corners with twelve equivalent Mg(2)Mg12 cuboctahedra, corners with twelve equivalent Zn(1)Mg3Zn9 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with six equivalent Zn(1)Mg3Zn9 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra, and  a faceface with one Zn(1)Mg3Zn9 cuboctahedra. In the second Mg site, Mg(2) is bonded to three equivalent Mg(1) and nine equivalent Mg(2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Zn(1)Mg3Zn9 cuboctahedra, corners with twelve equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with six equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with twelve equivalent Mg(2)Mg12 cuboctahedra,  a faceface with one Mg(1)Mg3Zn3 cuboctahedra,  a faceface with one Zn(1)Mg3Zn9 cuboctahedra, and faces with twelve equivalent Mg(2)Mg12 cuboctahedra. Zn(1) is bonded to three equivalent Mg(1) and nine equivalent Zn(1) atoms to form distorted ZnMg3Zn9 cuboctahedra that share corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Zn(1)Mg3Zn9 cuboctahedra, corners with twelve equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with six equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with twelve equivalent Zn(1)Mg3Zn9 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Mg(1)Mg3Zn3 cuboctahedra, and faces with twelve equivalent Zn(1)Mg3Zn9 cuboctahedra.
Mg2Zn crystallizes in the trigonal P-3m1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent Mg(2) and three equivalent Zn(1) atoms to form distorted MgMg3Zn3 cuboctahedra that share corners with twelve equivalent Mg(2)Mg12 cuboctahedra, corners with twelve equivalent Zn(1)Mg3Zn9 cuboctahedra, edges with six equivalent Mg(2)Mg12 cuboctahedra, edges with six equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with six equivalent Zn(1)Mg3Zn9 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra, and  a faceface with one Zn(1)Mg3Zn9 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.28 Å. All Mg(1)-Zn(1) bond lengths are 2.92 Å. In the second Mg site, Mg(2) is bonded to three equivalent Mg(1) and nine equivalent Mg(2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Zn(1)Mg3Zn9 cuboctahedra, corners with twelve equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with six equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with twelve equivalent Mg(2)Mg12 cuboctahedra,  a faceface with one Mg(1)Mg3Zn3 cuboctahedra,  a faceface with one Zn(1)Mg3Zn9 cuboctahedra, and faces with twelve equivalent Mg(2)Mg12 cuboctahedra. There are six shorter (3.05 Å) and three longer (3.26 Å) Mg(2)-Mg(2) bond lengths. Zn(1) is bonded to three equivalent Mg(1) and nine equivalent Zn(1) atoms to form distorted ZnMg3Zn9 cuboctahedra that share corners with six equivalent Mg(2)Mg12 cuboctahedra, corners with six equivalent Zn(1)Mg3Zn9 cuboctahedra, corners with twelve equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with six equivalent Mg(1)Mg3Zn3 cuboctahedra, edges with twelve equivalent Zn(1)Mg3Zn9 cuboctahedra,  a faceface with one Mg(2)Mg12 cuboctahedra,  a faceface with one Mg(1)Mg3Zn3 cuboctahedra, and faces with twelve equivalent Zn(1)Mg3Zn9 cuboctahedra. There are three shorter (2.71 Å) and six longer (3.05 Å) Zn(1)-Zn(1) bond lengths.