BaSrCaMg(SiO4)2 crystallizes in the trigonal P3m1 space group. Ba(1) is bonded to three equivalent O(1), three equivalent O(2), three equivalent O(3), and three equivalent O(4) atoms to form BaO12 cuboctahedra that share edges with six equivalent Ba(1)O12 cuboctahedra, edges with three equivalent Si(1)O4 tetrahedra, edges with three equivalent Si(2)O4 tetrahedra, and faces with two equivalent Mg(1)O6 octahedra. Sr(1) is bonded in a 10-coordinate geometry to one O(1), three equivalent O(3), and six equivalent O(4) atoms. Ca(1) is bonded in a 10-coordinate geometry to one O(2), three equivalent O(4), and six equivalent O(3) atoms. Mg(1) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form MgO6 octahedra that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1) and three equivalent O(3) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. In the second Si site, Si(2) is bonded to one O(2) and three equivalent O(4) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Ba(1), one Sr(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted linear geometry to three equivalent Ba(1), one Ca(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), two equivalent Ca(1), one Mg(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Sr(1), one Ca(1), one Mg(1), and one Si(2) atom.
BaSrCaMg(SiO4)2 crystallizes in the trigonal P3m1 space group. Ba(1) is bonded to three equivalent O(1), three equivalent O(2), three equivalent O(3), and three equivalent O(4) atoms to form BaO12 cuboctahedra that share edges with six equivalent Ba(1)O12 cuboctahedra, edges with three equivalent Si(1)O4 tetrahedra, edges with three equivalent Si(2)O4 tetrahedra, and faces with two equivalent Mg(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 3.19 Å. All Ba(1)-O(2) bond lengths are 3.19 Å. All Ba(1)-O(3) bond lengths are 2.80 Å. All Ba(1)-O(4) bond lengths are 2.81 Å. Sr(1) is bonded in a 10-coordinate geometry to one O(1), three equivalent O(3), and six equivalent O(4) atoms. The Sr(1)-O(1) bond length is 2.36 Å. All Sr(1)-O(3) bond lengths are 2.80 Å. All Sr(1)-O(4) bond lengths are 2.77 Å. Ca(1) is bonded in a 10-coordinate geometry to one O(2), three equivalent O(4), and six equivalent O(3) atoms. The Ca(1)-O(2) bond length is 2.27 Å. All Ca(1)-O(4) bond lengths are 2.85 Å. All Ca(1)-O(3) bond lengths are 2.77 Å. Mg(1) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form MgO6 octahedra that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. All Mg(1)-O(3) bond lengths are 2.08 Å. All Mg(1)-O(4) bond lengths are 2.09 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1) and three equivalent O(3) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. The Si(1)-O(1) bond length is 1.61 Å. All Si(1)-O(3) bond lengths are 1.66 Å. In the second Si site, Si(2) is bonded to one O(2) and three equivalent O(4) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and edges with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. The Si(2)-O(2) bond length is 1.63 Å. All Si(2)-O(4) bond lengths are 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Ba(1), one Sr(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted linear geometry to three equivalent Ba(1), one Ca(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1), one Sr(1), two equivalent Ca(1), one Mg(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Sr(1), one Ca(1), one Mg(1), and one Si(2) atom.