MgGd6WO12 crystallizes in the trigonal R3 space group. Mg(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form MgO6 octahedra that share  a faceface with one W(1)O6 octahedra. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Gd site, Gd(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. W(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form WO6 octahedra that share  a faceface with one Mg(1)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Gd(2), two equivalent Gd(1), and one W(1) atom to form distorted OGd3W trigonal pyramids that share corners with two equivalent O(3)Gd4Mg square pyramids, corners with six equivalent O(4)Gd4 tetrahedra, corners with four equivalent O(1)Gd3W trigonal pyramids, and edges with two equivalent O(3)Gd4Mg square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Mg(1), one Gd(1), two equivalent Gd(2), and one W(1) atom. In the third O site, O(3) is bonded to one Mg(1), two equivalent Gd(1), and two equivalent Gd(2) atoms to form distorted OGd4Mg square pyramids that share corners with two equivalent O(3)Gd4Mg square pyramids, corners with two equivalent O(4)Gd4 tetrahedra, corners with two equivalent O(1)Gd3W trigonal pyramids, edges with two equivalent O(3)Gd4Mg square pyramids, edges with three equivalent O(4)Gd4 tetrahedra, and edges with two equivalent O(1)Gd3W trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Gd(1) and two equivalent Gd(2) atoms to form OGd4 tetrahedra that share corners with two equivalent O(3)Gd4Mg square pyramids, corners with four equivalent O(4)Gd4 tetrahedra, corners with six equivalent O(1)Gd3W trigonal pyramids, and edges with three equivalent O(3)Gd4Mg square pyramids.
MgGd6WO12 crystallizes in the trigonal R3 space group. Mg(1) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form MgO6 octahedra that share  a faceface with one W(1)O6 octahedra. All Mg(1)-O(2) bond lengths are 2.14 Å. All Mg(1)-O(3) bond lengths are 2.17 Å. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 7-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. The Gd(1)-O(2) bond length is 2.94 Å. There is one shorter (2.34 Å) and one longer (2.40 Å) Gd(1)-O(1) bond length. There is one shorter (2.44 Å) and one longer (2.46 Å) Gd(1)-O(3) bond length. There is one shorter (2.28 Å) and one longer (2.31 Å) Gd(1)-O(4) bond length. In the second Gd site, Gd(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Gd(2)-O(1) bond length is 2.55 Å. There is one shorter (2.27 Å) and one longer (2.46 Å) Gd(2)-O(2) bond length. There is one shorter (2.29 Å) and one longer (2.51 Å) Gd(2)-O(3) bond length. There is one shorter (2.26 Å) and one longer (2.37 Å) Gd(2)-O(4) bond length. W(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form WO6 octahedra that share  a faceface with one Mg(1)O6 octahedra. All W(1)-O(1) bond lengths are 2.09 Å. All W(1)-O(2) bond lengths are 2.12 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Gd(2), two equivalent Gd(1), and one W(1) atom to form distorted OGd3W trigonal pyramids that share corners with two equivalent O(3)Gd4Mg square pyramids, corners with six equivalent O(4)Gd4 tetrahedra, corners with four equivalent O(1)Gd3W trigonal pyramids, and edges with two equivalent O(3)Gd4Mg square pyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Mg(1), one Gd(1), two equivalent Gd(2), and one W(1) atom. In the third O site, O(3) is bonded to one Mg(1), two equivalent Gd(1), and two equivalent Gd(2) atoms to form distorted OGd4Mg square pyramids that share corners with two equivalent O(3)Gd4Mg square pyramids, corners with two equivalent O(4)Gd4 tetrahedra, corners with two equivalent O(1)Gd3W trigonal pyramids, edges with two equivalent O(3)Gd4Mg square pyramids, edges with three equivalent O(4)Gd4 tetrahedra, and edges with two equivalent O(1)Gd3W trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Gd(1) and two equivalent Gd(2) atoms to form OGd4 tetrahedra that share corners with two equivalent O(3)Gd4Mg square pyramids, corners with four equivalent O(4)Gd4 tetrahedra, corners with six equivalent O(1)Gd3W trigonal pyramids, and edges with three equivalent O(3)Gd4Mg square pyramids.