Ho2Ge2O7 crystallizes in the monoclinic C2/m space group. Ho(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted HoO6 pentagonal pyramids that share corners with six equivalent Ge(1)O4 tetrahedra and edges with three equivalent Ho(1)O6 pentagonal pyramids. Ge(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form GeO4 tetrahedra that share corners with six equivalent Ho(1)O6 pentagonal pyramids and  a cornercorner with one Ge(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Ho(1) and one Ge(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ho(1) and one Ge(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Ge(1) atoms.
Ho2Ge2O7 crystallizes in the monoclinic C2/m space group. Ho(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted HoO6 pentagonal pyramids that share corners with six equivalent Ge(1)O4 tetrahedra and edges with three equivalent Ho(1)O6 pentagonal pyramids. Both Ho(1)-O(2) bond lengths are 2.25 Å. There are two shorter (2.22 Å) and two longer (2.30 Å) Ho(1)-O(1) bond lengths. Ge(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form GeO4 tetrahedra that share corners with six equivalent Ho(1)O6 pentagonal pyramids and  a cornercorner with one Ge(1)O4 tetrahedra. The Ge(1)-O(2) bond length is 1.75 Å. The Ge(1)-O(3) bond length is 1.75 Å. Both Ge(1)-O(1) bond lengths are 1.75 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Ho(1) and one Ge(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ho(1) and one Ge(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Ge(1) atoms.