K2BeSi4O13 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. Be(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form BeO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Be(1)O4 tetrahedra and corners with three equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Be(1)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(2) is bonded in a bent 120 degrees geometry to one Be(1) and one Si(1) atom. In the second O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(2), one Si(1), and one Si(2) atom. In the third O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fourth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fifth O site, O(6) is bonded in a distorted T-shaped geometry to one K(1) and two equivalent K(2) atoms. In the sixth O site, O(7) is bonded in a bent 120 degrees geometry to one K(1) and one K(2) atom. In the seventh O site, O(1) is bonded in a bent 120 degrees geometry to one Be(1) and one Si(2) atom.
K2BeSi4O13 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms. The K(1)-O(6) bond length is 2.96 Å. Both K(1)-O(4) bond lengths are 3.11 Å. Both K(1)-O(5) bond lengths are 2.94 Å. Both K(1)-O(7) bond lengths are 2.73 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. Both K(2)-O(3) bond lengths are 2.93 Å. Both K(2)-O(6) bond lengths are 2.91 Å. Both K(2)-O(7) bond lengths are 2.86 Å. Be(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form BeO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. Both Be(1)-O(1) bond lengths are 1.66 Å. Both Be(1)-O(2) bond lengths are 1.63 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Be(1)O4 tetrahedra and corners with three equivalent Si(2)O4 tetrahedra. The Si(1)-O(2) bond length is 1.60 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.64 Å. The Si(1)-O(5) bond length is 1.66 Å. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Be(1)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. The Si(2)-O(1) bond length is 1.61 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.64 Å. The Si(2)-O(5) bond length is 1.66 Å. There are seven inequivalent O sites. In the first O site, O(2) is bonded in a bent 120 degrees geometry to one Be(1) and one Si(1) atom. In the second O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(2), one Si(1), and one Si(2) atom. In the third O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fourth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the fifth O site, O(6) is bonded in a distorted T-shaped geometry to one K(1) and two equivalent K(2) atoms. In the sixth O site, O(7) is bonded in a bent 120 degrees geometry to one K(1) and one K(2) atom. In the seventh O site, O(1) is bonded in a bent 120 degrees geometry to one Be(1) and one Si(2) atom.