Mg2Ca is Molybdenite structured and crystallizes in the hexagonal P6_3/mmc space group. Ca(1) is bonded to six equivalent Ca(1) and six equivalent Mg(1) atoms to form CaCa6Mg6 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, edges with six equivalent Ca(1)Ca6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, faces with six equivalent Ca(1)Ca6Mg6 cuboctahedra, and faces with fourteen equivalent Mg(1)Ca3Mg9 cuboctahedra. Mg(1) is bonded to three equivalent Ca(1) and nine equivalent Mg(1) atoms to form distorted MgCa3Mg9 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, edges with six equivalent Ca(1)Ca6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, faces with seven equivalent Ca(1)Ca6Mg6 cuboctahedra, and faces with thirteen equivalent Mg(1)Ca3Mg9 cuboctahedra.
Mg2Ca is Molybdenite structured and crystallizes in the hexagonal P6_3/mmc space group. Ca(1) is bonded to six equivalent Ca(1) and six equivalent Mg(1) atoms to form CaCa6Mg6 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, edges with six equivalent Ca(1)Ca6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, faces with six equivalent Ca(1)Ca6Mg6 cuboctahedra, and faces with fourteen equivalent Mg(1)Ca3Mg9 cuboctahedra. All Ca(1)-Ca(1) bond lengths are 3.47 Å. All Ca(1)-Mg(1) bond lengths are 3.50 Å. Mg(1) is bonded to three equivalent Ca(1) and nine equivalent Mg(1) atoms to form distorted MgCa3Mg9 cuboctahedra that share corners with six equivalent Ca(1)Ca6Mg6 cuboctahedra, corners with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, edges with six equivalent Ca(1)Ca6Mg6 cuboctahedra, edges with twelve equivalent Mg(1)Ca3Mg9 cuboctahedra, faces with seven equivalent Ca(1)Ca6Mg6 cuboctahedra, and faces with thirteen equivalent Mg(1)Ca3Mg9 cuboctahedra. There are three shorter (3.33 Å) and six longer (3.47 Å) Mg(1)-Mg(1) bond lengths.