MgO crystallizes in the monoclinic Cm space group. There are twelve inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(4), one O(5), and two equivalent O(1) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(3)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(6)O5 trigonal bipyramid, corners with two equivalent Mg(5)O5 trigonal bipyramids, corners with two equivalent Mg(8)O4 trigonal pyramids, and edges with two equivalent Mg(10)O5 trigonal bipyramids. In the second Mg site, Mg(2) is bonded to one O(3), one O(6), and two equivalent O(7) atoms to form MgO4 trigonal pyramids that share  a cornercorner with one Mg(12)O4 tetrahedra,  a cornercorner with one Mg(5)O5 trigonal bipyramid, corners with two equivalent Mg(7)O5 trigonal bipyramids, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(9)O4 trigonal pyramids, and edges with two equivalent Mg(11)O5 trigonal bipyramids. In the third Mg site, Mg(3) is bonded to one O(2), one O(4), and two equivalent O(9) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(3)O4 tetrahedra, corners with two equivalent Mg(8)O4 trigonal pyramids, corners with two equivalent Mg(9)O4 trigonal pyramids, and edges with two equivalent Mg(10)O5 trigonal bipyramids. In the fourth Mg site, Mg(4) is bonded in a see-saw-like geometry to one O(2), one O(6), and two equivalent O(11) atoms. In the fifth Mg site, Mg(5) is bonded to one O(1), one O(12), one O(3), and two equivalent O(8) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(5)O5 trigonal bipyramids, corners with two equivalent Mg(7)O5 trigonal bipyramids,  a cornercorner with one Mg(2)O4 trigonal pyramid,  a cornercorner with one Mg(8)O4 trigonal pyramid,  an edgeedge with one Mg(12)O4 tetrahedra,  an edgeedge with one Mg(10)O5 trigonal bipyramid, edges with two equivalent Mg(11)O5 trigonal bipyramids, and edges with two equivalent Mg(6)O5 trigonal bipyramids. In the sixth Mg site, Mg(6) is bonded to one O(10), one O(5), one O(8), and two equivalent O(12) atoms to form MgO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(11)O5 trigonal bipyramid, corners with two equivalent Mg(10)O5 trigonal bipyramids, corners with two equivalent Mg(6)O5 trigonal bipyramids,  an edgeedge with one Mg(7)O5 trigonal bipyramid, edges with two equivalent Mg(5)O5 trigonal bipyramids, and edges with two equivalent Mg(8)O4 trigonal pyramids. In the seventh Mg site, Mg(7) is bonded to one O(10), one O(11), one O(8), and two equivalent O(6) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(12)O4 tetrahedra, corners with two equivalent Mg(5)O5 trigonal bipyramids, corners with two equivalent Mg(7)O5 trigonal bipyramids,  a cornercorner with one Mg(9)O4 trigonal pyramid, corners with two equivalent Mg(2)O4 trigonal pyramids,  an edgeedge with one Mg(11)O5 trigonal bipyramid, and  an edgeedge with one Mg(6)O5 trigonal bipyramid. In the eighth Mg site, Mg(8) is bonded to one O(12), one O(9), and two equivalent O(5) atoms to form MgO4 trigonal pyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(3)O4 tetrahedra,  a cornercorner with one Mg(5)O5 trigonal bipyramid, corners with two equivalent Mg(8)O4 trigonal pyramids,  an edgeedge with one Mg(10)O5 trigonal bipyramid, and edges with two equivalent Mg(6)O5 trigonal bipyramids. In the ninth Mg site, Mg(9) is bonded to one O(11), one O(7), and two equivalent O(2) atoms to form MgO4 trigonal pyramids that share corners with two equivalent Mg(3)O4 tetrahedra,  a cornercorner with one Mg(7)O5 trigonal bipyramid, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(9)O4 trigonal pyramids, and  an edgeedge with one Mg(11)O5 trigonal bipyramid. In the tenth Mg site, Mg(10) is bonded to one O(1), one O(12), one O(9), and two equivalent O(4) atoms to form MgO5 trigonal bipyramids that share  a cornercorner with one Mg(12)O4 tetrahedra, corners with two equivalent Mg(10)O5 trigonal bipyramids, corners with two equivalent Mg(6)O5 trigonal bipyramids, edges with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Mg(3)O4 tetrahedra,  an edgeedge with one Mg(5)O5 trigonal bipyramid, and  an edgeedge with one Mg(8)O4 trigonal pyramid. In the eleventh Mg site, Mg(11) is bonded to one O(11), one O(7), one O(8), and two equivalent O(3) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(6)O5 trigonal bipyramid, corners with two equivalent Mg(11)O5 trigonal bipyramids,  an edgeedge with one Mg(7)O5 trigonal bipyramid, edges with two equivalent Mg(5)O5 trigonal bipyramids,  an edgeedge with one Mg(9)O4 trigonal pyramid, and edges with two equivalent Mg(2)O4 trigonal pyramids. In the twelfth Mg site, Mg(12) is bonded to one O(1), one O(3), and two equivalent O(10) atoms to form distorted MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(10)O5 trigonal bipyramid, corners with two equivalent Mg(11)O5 trigonal bipyramids, corners with two equivalent Mg(6)O5 trigonal bipyramids, corners with two equivalent Mg(7)O5 trigonal bipyramids,  a cornercorner with one Mg(2)O4 trigonal pyramid, and  an edgeedge with one Mg(5)O5 trigonal bipyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Mg(10), one Mg(12), one Mg(5), and two equivalent Mg(1) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(10)Mg4 tetrahedra, corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(8)Mg5 trigonal bipyramids,  a cornercorner with one O(9)Mg4 trigonal pyramid, corners with two equivalent O(5)Mg4 trigonal pyramids,  an edgeedge with one O(12)Mg5 trigonal bipyramid, and  an edgeedge with one O(3)Mg5 trigonal bipyramid. In the second O site, O(2) is bonded to one Mg(3), one Mg(4), and two equivalent Mg(9) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(6)Mg4 trigonal pyramid, corners with two equivalent O(2)Mg4 trigonal pyramids, corners with two equivalent O(7)Mg4 trigonal pyramids, corners with two equivalent O(9)Mg4 trigonal pyramids, and edges with two equivalent O(11)Mg5 trigonal bipyramids. In the third O site, O(3) is bonded to one Mg(12), one Mg(2), one Mg(5), and two equivalent Mg(11) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(12)Mg5 trigonal bipyramid, corners with two equivalent O(11)Mg5 trigonal bipyramids, corners with two equivalent O(3)Mg5 trigonal bipyramids,  a cornercorner with one O(6)Mg4 trigonal pyramid,  an edgeedge with one O(1)Mg5 trigonal bipyramid, edges with two equivalent O(8)Mg5 trigonal bipyramids, and edges with two equivalent O(7)Mg4 trigonal pyramids. In the fourth O site, O(4) is bonded in a see-saw-like geometry to one Mg(1), one Mg(3), and two equivalent Mg(10) atoms. In the fifth O site, O(5) is bonded to one Mg(1), one Mg(6), and two equivalent Mg(8) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(10)Mg4 tetrahedra,  a cornercorner with one O(8)Mg5 trigonal bipyramid, corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(5)Mg4 trigonal pyramids, corners with two equivalent O(9)Mg4 trigonal pyramids, and edges with two equivalent O(12)Mg5 trigonal bipyramids. In the sixth O site, O(6) is bonded to one Mg(2), one Mg(4), and two equivalent Mg(7) atoms to form distorted OMg4 trigonal pyramids that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(3)Mg5 trigonal bipyramid, corners with two equivalent O(8)Mg5 trigonal bipyramids,  a cornercorner with one O(2)Mg4 trigonal pyramid, corners with two equivalent O(6)Mg4 trigonal pyramids, corners with two equivalent O(7)Mg4 trigonal pyramids, and edges with two equivalent O(11)Mg5 trigonal bipyramids. In the seventh O site, O(7) is bonded to one Mg(11), one Mg(9), and two equivalent Mg(2) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(8)Mg5 trigonal bipyramid, corners with two equivalent O(2)Mg4 trigonal pyramids, corners with two equivalent O(6)Mg4 trigonal pyramids, corners with two equivalent O(7)Mg4 trigonal pyramids,  an edgeedge with one O(11)Mg5 trigonal bipyramid, and edges with two equivalent O(3)Mg5 trigonal bipyramids. In the eighth O site, O(8) is bonded to one Mg(11), one Mg(6), one Mg(7), and two equivalent Mg(5) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(8)Mg5 trigonal bipyramids,  a cornercorner with one O(5)Mg4 trigonal pyramid,  a cornercorner with one O(7)Mg4 trigonal pyramid, corners with two equivalent O(6)Mg4 trigonal pyramids,  an edgeedge with one O(10)Mg4 tetrahedra,  an edgeedge with one O(11)Mg5 trigonal bipyramid, edges with two equivalent O(12)Mg5 trigonal bipyramids, and edges with two equivalent O(3)Mg5 trigonal bipyramids. In the ninth O site, O(9) is bonded to one Mg(10), one Mg(8), and two equivalent Mg(3) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(1)Mg5 trigonal bipyramid, corners with two equivalent O(2)Mg4 trigonal pyramids, corners with two equivalent O(5)Mg4 trigonal pyramids, corners with two equivalent O(9)Mg4 trigonal pyramids, and  an edgeedge with one O(12)Mg5 trigonal bipyramid. In the tenth O site, O(10) is bonded to one Mg(6), one Mg(7), and two equivalent Mg(12) atoms to form distorted OMg4 tetrahedra that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(11)Mg5 trigonal bipyramid, corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(12)Mg5 trigonal bipyramids, corners with two equivalent O(3)Mg5 trigonal bipyramids,  a cornercorner with one O(5)Mg4 trigonal pyramid, corners with two equivalent O(6)Mg4 trigonal pyramids, and  an edgeedge with one O(8)Mg5 trigonal bipyramid. In the eleventh O site, O(11) is bonded to one Mg(11), one Mg(7), one Mg(9), and two equivalent Mg(4) atoms to form OMg5 trigonal bipyramids that share  a cornercorner with one O(10)Mg4 tetrahedra, corners with two equivalent O(11)Mg5 trigonal bipyramids, corners with two equivalent O(3)Mg5 trigonal bipyramids,  an edgeedge with one O(8)Mg5 trigonal bipyramid,  an edgeedge with one O(7)Mg4 trigonal pyramid, edges with two equivalent O(2)Mg4 trigonal pyramids, and edges with two equivalent O(6)Mg4 trigonal pyramids. In the twelfth O site, O(12) is bonded to one Mg(10), one Mg(5), one Mg(8), and two equivalent Mg(6) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(3)Mg5 trigonal bipyramid, corners with two equivalent O(12)Mg5 trigonal bipyramids,  an edgeedge with one O(1)Mg5 trigonal bipyramid, edges with two equivalent O(8)Mg5 trigonal bipyramids,  an edgeedge with one O(9)Mg4 trigonal pyramid, and edges with two equivalent O(5)Mg4 trigonal pyramids.
MgO crystallizes in the monoclinic Cm space group. There are twelve inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(4), one O(5), and two equivalent O(1) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(3)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(6)O5 trigonal bipyramid, corners with two equivalent Mg(5)O5 trigonal bipyramids, corners with two equivalent Mg(8)O4 trigonal pyramids, and edges with two equivalent Mg(10)O5 trigonal bipyramids. The Mg(1)-O(4) bond length is 1.98 Å. The Mg(1)-O(5) bond length is 1.96 Å. Both Mg(1)-O(1) bond lengths are 2.06 Å. In the second Mg site, Mg(2) is bonded to one O(3), one O(6), and two equivalent O(7) atoms to form MgO4 trigonal pyramids that share  a cornercorner with one Mg(12)O4 tetrahedra,  a cornercorner with one Mg(5)O5 trigonal bipyramid, corners with two equivalent Mg(7)O5 trigonal bipyramids, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(9)O4 trigonal pyramids, and edges with two equivalent Mg(11)O5 trigonal bipyramids. The Mg(2)-O(3) bond length is 2.09 Å. The Mg(2)-O(6) bond length is 1.96 Å. Both Mg(2)-O(7) bond lengths are 1.98 Å. In the third Mg site, Mg(3) is bonded to one O(2), one O(4), and two equivalent O(9) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(3)O4 tetrahedra, corners with two equivalent Mg(8)O4 trigonal pyramids, corners with two equivalent Mg(9)O4 trigonal pyramids, and edges with two equivalent Mg(10)O5 trigonal bipyramids. The Mg(3)-O(2) bond length is 1.98 Å. The Mg(3)-O(4) bond length is 2.02 Å. Both Mg(3)-O(9) bond lengths are 1.98 Å. In the fourth Mg site, Mg(4) is bonded in a see-saw-like geometry to one O(2), one O(6), and two equivalent O(11) atoms. The Mg(4)-O(2) bond length is 2.03 Å. The Mg(4)-O(6) bond length is 1.99 Å. Both Mg(4)-O(11) bond lengths are 1.96 Å. In the fifth Mg site, Mg(5) is bonded to one O(1), one O(12), one O(3), and two equivalent O(8) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(5)O5 trigonal bipyramids, corners with two equivalent Mg(7)O5 trigonal bipyramids,  a cornercorner with one Mg(2)O4 trigonal pyramid,  a cornercorner with one Mg(8)O4 trigonal pyramid,  an edgeedge with one Mg(12)O4 tetrahedra,  an edgeedge with one Mg(10)O5 trigonal bipyramid, edges with two equivalent Mg(11)O5 trigonal bipyramids, and edges with two equivalent Mg(6)O5 trigonal bipyramids. The Mg(5)-O(1) bond length is 2.08 Å. The Mg(5)-O(12) bond length is 2.08 Å. The Mg(5)-O(3) bond length is 2.20 Å. Both Mg(5)-O(8) bond lengths are 2.04 Å. In the sixth Mg site, Mg(6) is bonded to one O(10), one O(5), one O(8), and two equivalent O(12) atoms to form MgO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(11)O5 trigonal bipyramid, corners with two equivalent Mg(10)O5 trigonal bipyramids, corners with two equivalent Mg(6)O5 trigonal bipyramids,  an edgeedge with one Mg(7)O5 trigonal bipyramid, edges with two equivalent Mg(5)O5 trigonal bipyramids, and edges with two equivalent Mg(8)O4 trigonal pyramids. The Mg(6)-O(10) bond length is 2.02 Å. The Mg(6)-O(5) bond length is 2.12 Å. The Mg(6)-O(8) bond length is 2.18 Å. Both Mg(6)-O(12) bond lengths are 2.02 Å. In the seventh Mg site, Mg(7) is bonded to one O(10), one O(11), one O(8), and two equivalent O(6) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(12)O4 tetrahedra, corners with two equivalent Mg(5)O5 trigonal bipyramids, corners with two equivalent Mg(7)O5 trigonal bipyramids,  a cornercorner with one Mg(9)O4 trigonal pyramid, corners with two equivalent Mg(2)O4 trigonal pyramids,  an edgeedge with one Mg(11)O5 trigonal bipyramid, and  an edgeedge with one Mg(6)O5 trigonal bipyramid. The Mg(7)-O(10) bond length is 2.05 Å. The Mg(7)-O(11) bond length is 2.18 Å. The Mg(7)-O(8) bond length is 2.09 Å. Both Mg(7)-O(6) bond lengths are 2.06 Å. In the eighth Mg site, Mg(8) is bonded to one O(12), one O(9), and two equivalent O(5) atoms to form MgO4 trigonal pyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(3)O4 tetrahedra,  a cornercorner with one Mg(5)O5 trigonal bipyramid, corners with two equivalent Mg(8)O4 trigonal pyramids,  an edgeedge with one Mg(10)O5 trigonal bipyramid, and edges with two equivalent Mg(6)O5 trigonal bipyramids. The Mg(8)-O(12) bond length is 2.13 Å. The Mg(8)-O(9) bond length is 1.95 Å. Both Mg(8)-O(5) bond lengths are 1.98 Å. In the ninth Mg site, Mg(9) is bonded to one O(11), one O(7), and two equivalent O(2) atoms to form MgO4 trigonal pyramids that share corners with two equivalent Mg(3)O4 tetrahedra,  a cornercorner with one Mg(7)O5 trigonal bipyramid, corners with two equivalent Mg(2)O4 trigonal pyramids, corners with two equivalent Mg(9)O4 trigonal pyramids, and  an edgeedge with one Mg(11)O5 trigonal bipyramid. The Mg(9)-O(11) bond length is 2.09 Å. The Mg(9)-O(7) bond length is 1.96 Å. Both Mg(9)-O(2) bond lengths are 2.00 Å. In the tenth Mg site, Mg(10) is bonded to one O(1), one O(12), one O(9), and two equivalent O(4) atoms to form MgO5 trigonal bipyramids that share  a cornercorner with one Mg(12)O4 tetrahedra, corners with two equivalent Mg(10)O5 trigonal bipyramids, corners with two equivalent Mg(6)O5 trigonal bipyramids, edges with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Mg(3)O4 tetrahedra,  an edgeedge with one Mg(5)O5 trigonal bipyramid, and  an edgeedge with one Mg(8)O4 trigonal pyramid. The Mg(10)-O(1) bond length is 2.24 Å. The Mg(10)-O(12) bond length is 2.02 Å. The Mg(10)-O(9) bond length is 2.15 Å. Both Mg(10)-O(4) bond lengths are 1.97 Å. In the eleventh Mg site, Mg(11) is bonded to one O(11), one O(7), one O(8), and two equivalent O(3) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(6)O5 trigonal bipyramid, corners with two equivalent Mg(11)O5 trigonal bipyramids,  an edgeedge with one Mg(7)O5 trigonal bipyramid, edges with two equivalent Mg(5)O5 trigonal bipyramids,  an edgeedge with one Mg(9)O4 trigonal pyramid, and edges with two equivalent Mg(2)O4 trigonal pyramids. The Mg(11)-O(11) bond length is 2.00 Å. The Mg(11)-O(7) bond length is 2.21 Å. The Mg(11)-O(8) bond length is 2.09 Å. Both Mg(11)-O(3) bond lengths are 2.02 Å. In the twelfth Mg site, Mg(12) is bonded to one O(1), one O(3), and two equivalent O(10) atoms to form distorted MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Mg(12)O4 tetrahedra,  a cornercorner with one Mg(10)O5 trigonal bipyramid, corners with two equivalent Mg(11)O5 trigonal bipyramids, corners with two equivalent Mg(6)O5 trigonal bipyramids, corners with two equivalent Mg(7)O5 trigonal bipyramids,  a cornercorner with one Mg(2)O4 trigonal pyramid, and  an edgeedge with one Mg(5)O5 trigonal bipyramid. The Mg(12)-O(1) bond length is 2.05 Å. The Mg(12)-O(3) bond length is 2.01 Å. Both Mg(12)-O(10) bond lengths are 1.99 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Mg(10), one Mg(12), one Mg(5), and two equivalent Mg(1) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(10)Mg4 tetrahedra, corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(8)Mg5 trigonal bipyramids,  a cornercorner with one O(9)Mg4 trigonal pyramid, corners with two equivalent O(5)Mg4 trigonal pyramids,  an edgeedge with one O(12)Mg5 trigonal bipyramid, and  an edgeedge with one O(3)Mg5 trigonal bipyramid. In the second O site, O(2) is bonded to one Mg(3), one Mg(4), and two equivalent Mg(9) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(6)Mg4 trigonal pyramid, corners with two equivalent O(2)Mg4 trigonal pyramids, corners with two equivalent O(7)Mg4 trigonal pyramids, corners with two equivalent O(9)Mg4 trigonal pyramids, and edges with two equivalent O(11)Mg5 trigonal bipyramids. In the third O site, O(3) is bonded to one Mg(12), one Mg(2), one Mg(5), and two equivalent Mg(11) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(12)Mg5 trigonal bipyramid, corners with two equivalent O(11)Mg5 trigonal bipyramids, corners with two equivalent O(3)Mg5 trigonal bipyramids,  a cornercorner with one O(6)Mg4 trigonal pyramid,  an edgeedge with one O(1)Mg5 trigonal bipyramid, edges with two equivalent O(8)Mg5 trigonal bipyramids, and edges with two equivalent O(7)Mg4 trigonal pyramids. In the fourth O site, O(4) is bonded in a see-saw-like geometry to one Mg(1), one Mg(3), and two equivalent Mg(10) atoms. In the fifth O site, O(5) is bonded to one Mg(1), one Mg(6), and two equivalent Mg(8) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(10)Mg4 tetrahedra,  a cornercorner with one O(8)Mg5 trigonal bipyramid, corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(5)Mg4 trigonal pyramids, corners with two equivalent O(9)Mg4 trigonal pyramids, and edges with two equivalent O(12)Mg5 trigonal bipyramids. In the sixth O site, O(6) is bonded to one Mg(2), one Mg(4), and two equivalent Mg(7) atoms to form distorted OMg4 trigonal pyramids that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(3)Mg5 trigonal bipyramid, corners with two equivalent O(8)Mg5 trigonal bipyramids,  a cornercorner with one O(2)Mg4 trigonal pyramid, corners with two equivalent O(6)Mg4 trigonal pyramids, corners with two equivalent O(7)Mg4 trigonal pyramids, and edges with two equivalent O(11)Mg5 trigonal bipyramids. In the seventh O site, O(7) is bonded to one Mg(11), one Mg(9), and two equivalent Mg(2) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(8)Mg5 trigonal bipyramid, corners with two equivalent O(2)Mg4 trigonal pyramids, corners with two equivalent O(6)Mg4 trigonal pyramids, corners with two equivalent O(7)Mg4 trigonal pyramids,  an edgeedge with one O(11)Mg5 trigonal bipyramid, and edges with two equivalent O(3)Mg5 trigonal bipyramids. In the eighth O site, O(8) is bonded to one Mg(11), one Mg(6), one Mg(7), and two equivalent Mg(5) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(8)Mg5 trigonal bipyramids,  a cornercorner with one O(5)Mg4 trigonal pyramid,  a cornercorner with one O(7)Mg4 trigonal pyramid, corners with two equivalent O(6)Mg4 trigonal pyramids,  an edgeedge with one O(10)Mg4 tetrahedra,  an edgeedge with one O(11)Mg5 trigonal bipyramid, edges with two equivalent O(12)Mg5 trigonal bipyramids, and edges with two equivalent O(3)Mg5 trigonal bipyramids. In the ninth O site, O(9) is bonded to one Mg(10), one Mg(8), and two equivalent Mg(3) atoms to form OMg4 trigonal pyramids that share  a cornercorner with one O(1)Mg5 trigonal bipyramid, corners with two equivalent O(2)Mg4 trigonal pyramids, corners with two equivalent O(5)Mg4 trigonal pyramids, corners with two equivalent O(9)Mg4 trigonal pyramids, and  an edgeedge with one O(12)Mg5 trigonal bipyramid. In the tenth O site, O(10) is bonded to one Mg(6), one Mg(7), and two equivalent Mg(12) atoms to form distorted OMg4 tetrahedra that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(11)Mg5 trigonal bipyramid, corners with two equivalent O(1)Mg5 trigonal bipyramids, corners with two equivalent O(12)Mg5 trigonal bipyramids, corners with two equivalent O(3)Mg5 trigonal bipyramids,  a cornercorner with one O(5)Mg4 trigonal pyramid, corners with two equivalent O(6)Mg4 trigonal pyramids, and  an edgeedge with one O(8)Mg5 trigonal bipyramid. In the eleventh O site, O(11) is bonded to one Mg(11), one Mg(7), one Mg(9), and two equivalent Mg(4) atoms to form OMg5 trigonal bipyramids that share  a cornercorner with one O(10)Mg4 tetrahedra, corners with two equivalent O(11)Mg5 trigonal bipyramids, corners with two equivalent O(3)Mg5 trigonal bipyramids,  an edgeedge with one O(8)Mg5 trigonal bipyramid,  an edgeedge with one O(7)Mg4 trigonal pyramid, edges with two equivalent O(2)Mg4 trigonal pyramids, and edges with two equivalent O(6)Mg4 trigonal pyramids. In the twelfth O site, O(12) is bonded to one Mg(10), one Mg(5), one Mg(8), and two equivalent Mg(6) atoms to form OMg5 trigonal bipyramids that share corners with two equivalent O(10)Mg4 tetrahedra,  a cornercorner with one O(3)Mg5 trigonal bipyramid, corners with two equivalent O(12)Mg5 trigonal bipyramids,  an edgeedge with one O(1)Mg5 trigonal bipyramid, edges with two equivalent O(8)Mg5 trigonal bipyramids,  an edgeedge with one O(9)Mg4 trigonal pyramid, and edges with two equivalent O(5)Mg4 trigonal pyramids.