Mg3Ca crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1) and eight equivalent Mg(2) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to two equivalent Ca(1) and eight equivalent Mg(2) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to four equivalent Ca(1) and four equivalent Mg(1) atoms.
Mg3Ca crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1) and eight equivalent Mg(2) atoms. Both Ca(1)-Mg(1) bond lengths are 3.49 Å. All Ca(1)-Mg(2) bond lengths are 3.25 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to two equivalent Ca(1) and eight equivalent Mg(2) atoms. All Mg(1)-Mg(2) bond lengths are 3.25 Å. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to four equivalent Ca(1) and four equivalent Mg(1) atoms.