Eu2SiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms. In the second Eu site, Eu(2) is bonded in a 7-coordinate geometry to one O(4), one O(5), two equivalent O(3), and three equivalent O(1) atoms. Si(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted corner-sharing SiO5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1) and three equivalent Eu(2) atoms to form OEu4 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with five equivalent O(3)Eu3Si tetrahedra, corners with five equivalent O(5)Eu3Si tetrahedra,  an edgeedge with one O(3)Eu3Si tetrahedra, and edges with two equivalent O(1)Eu4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Eu(1) and one Si(1) atom. In the third O site, O(3) is bonded to one Eu(1), two equivalent Eu(2), and one Si(1) atom to form distorted OEu3Si tetrahedra that share  a cornercorner with one O(5)Eu3Si tetrahedra, corners with two equivalent O(3)Eu3Si tetrahedra, corners with five equivalent O(1)Eu4 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, and edges with two equivalent O(5)Eu3Si tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Eu(1), one Eu(2), and two equivalent Si(1) atoms. In the fifth O site, O(5) is bonded to one Eu(2), two equivalent Eu(1), and one Si(1) atom to form distorted OEu3Si tetrahedra that share  a cornercorner with one O(3)Eu3Si tetrahedra, corners with two equivalent O(5)Eu3Si tetrahedra, corners with five equivalent O(1)Eu4 tetrahedra, and edges with two equivalent O(3)Eu3Si tetrahedra.
Eu2SiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms. The Eu(1)-O(1) bond length is 2.32 Å. The Eu(1)-O(3) bond length is 2.50 Å. The Eu(1)-O(4) bond length is 2.73 Å. Both Eu(1)-O(2) bond lengths are 2.38 Å. Both Eu(1)-O(5) bond lengths are 2.40 Å. In the second Eu site, Eu(2) is bonded in a 7-coordinate geometry to one O(4), one O(5), two equivalent O(3), and three equivalent O(1) atoms. The Eu(2)-O(4) bond length is 2.54 Å. The Eu(2)-O(5) bond length is 2.49 Å. Both Eu(2)-O(3) bond lengths are 2.43 Å. There is one shorter (2.34 Å) and two longer (2.36 Å) Eu(2)-O(1) bond lengths. Si(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted corner-sharing SiO5 trigonal bipyramids. The Si(1)-O(2) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.69 Å. The Si(1)-O(5) bond length is 1.70 Å. Both Si(1)-O(4) bond lengths are 1.91 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1) and three equivalent Eu(2) atoms to form OEu4 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with five equivalent O(3)Eu3Si tetrahedra, corners with five equivalent O(5)Eu3Si tetrahedra,  an edgeedge with one O(3)Eu3Si tetrahedra, and edges with two equivalent O(1)Eu4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Eu(1) and one Si(1) atom. In the third O site, O(3) is bonded to one Eu(1), two equivalent Eu(2), and one Si(1) atom to form distorted OEu3Si tetrahedra that share  a cornercorner with one O(5)Eu3Si tetrahedra, corners with two equivalent O(3)Eu3Si tetrahedra, corners with five equivalent O(1)Eu4 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, and edges with two equivalent O(5)Eu3Si tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Eu(1), one Eu(2), and two equivalent Si(1) atoms. In the fifth O site, O(5) is bonded to one Eu(2), two equivalent Eu(1), and one Si(1) atom to form distorted OEu3Si tetrahedra that share  a cornercorner with one O(3)Eu3Si tetrahedra, corners with two equivalent O(5)Eu3Si tetrahedra, corners with five equivalent O(1)Eu4 tetrahedra, and edges with two equivalent O(3)Eu3Si tetrahedra.