Be2Y2Fe(SiO5)2 is Esseneite-derived structured and crystallizes in the monoclinic P2_1/c space group. Be(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form BeO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with three equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 63°. Y(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Be(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Be(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with three equivalent Be(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 65-69°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Be(1), one Y(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded to one Be(1), two equivalent Y(1), and one Fe(1) atom to form distorted corner-sharing OY2BeFe tetrahedra. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Be(1), one Y(1), one Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Y(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Be(1), two equivalent Y(1), and one Si(1) atom.
Be2Y2Fe(SiO5)2 is Esseneite-derived structured and crystallizes in the monoclinic P2_1/c space group. Be(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form BeO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with three equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 63°. The Be(1)-O(1) bond length is 1.65 Å. The Be(1)-O(2) bond length is 1.59 Å. The Be(1)-O(3) bond length is 1.66 Å. The Be(1)-O(5) bond length is 1.65 Å. Y(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. The Y(1)-O(1) bond length is 2.39 Å. The Y(1)-O(3) bond length is 2.40 Å. There is one shorter (2.39 Å) and one longer (2.51 Å) Y(1)-O(2) bond length. There is one shorter (2.32 Å) and one longer (2.33 Å) Y(1)-O(4) bond length. There is one shorter (2.46 Å) and one longer (2.72 Å) Y(1)-O(5) bond length. Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Be(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Be(1)O4 tetrahedra. Both Fe(1)-O(1) bond lengths are 2.23 Å. Both Fe(1)-O(2) bond lengths are 2.05 Å. Both Fe(1)-O(3) bond lengths are 2.30 Å. Si(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with three equivalent Be(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 65-69°. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.63 Å. The Si(1)-O(5) bond length is 1.64 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Be(1), one Y(1), one Fe(1), and one Si(1) atom. In the second O site, O(2) is bonded to one Be(1), two equivalent Y(1), and one Fe(1) atom to form distorted corner-sharing OY2BeFe tetrahedra. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Be(1), one Y(1), one Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Y(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Be(1), two equivalent Y(1), and one Si(1) atom.