Li2MgSiO4 is beta beryllia-derived structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with two equivalent Li(2)O4 tetrahedra, corners with four equivalent Mg(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. Mg(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form MgO4 tetrahedra that share corners with two equivalent Li(2)O4 tetrahedra, corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and corners with four equivalent Mg(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form a mixture of corner and edge-sharing OLi2MgSi tetrahedra. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form corner-sharing OLi2MgSi tetrahedra. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form a mixture of corner and edge-sharing OLi2MgSi tetrahedra. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OLi2MgSi trigonal pyramids.
Li2MgSiO4 is beta beryllia-derived structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with two equivalent Li(2)O4 tetrahedra, corners with four equivalent Mg(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. The Li(1)-O(1) bond length is 2.04 Å. The Li(1)-O(2) bond length is 1.96 Å. The Li(1)-O(3) bond length is 2.02 Å. The Li(1)-O(4) bond length is 1.97 Å. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. The Li(2)-O(1) bond length is 2.00 Å. The Li(2)-O(2) bond length is 1.96 Å. The Li(2)-O(3) bond length is 2.10 Å. The Li(2)-O(4) bond length is 2.09 Å. Mg(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form MgO4 tetrahedra that share corners with two equivalent Li(2)O4 tetrahedra, corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. The Mg(1)-O(1) bond length is 1.97 Å. The Mg(1)-O(2) bond length is 1.96 Å. The Mg(1)-O(3) bond length is 2.01 Å. The Mg(1)-O(4) bond length is 1.97 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and corners with four equivalent Mg(1)O4 tetrahedra. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.65 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form a mixture of corner and edge-sharing OLi2MgSi tetrahedra. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form corner-sharing OLi2MgSi tetrahedra. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form a mixture of corner and edge-sharing OLi2MgSi tetrahedra. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Mg(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OLi2MgSi trigonal pyramids.