Ca2Ga2GeO7 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(6), one O(7), two equivalent O(2), and two equivalent O(5) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(6), one O(7), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form GaO4 tetrahedra that share corners with two equivalent Ga(2)O4 tetrahedra and corners with two equivalent Ge(1)O4 tetrahedra. In the second Ga site, Ga(2) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form distorted GaO4 tetrahedra that share  a cornercorner with one Ge(1)O4 tetrahedra and corners with two equivalent Ga(1)O4 tetrahedra. Ge(1) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form GeO4 tetrahedra that share  a cornercorner with one Ga(2)O4 tetrahedra and corners with two equivalent Ga(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(2), one Ga(2), and one Ge(1) atom to form distorted OCa2GaGe tetrahedra that share corners with two equivalent O(2)Ca3Ga tetrahedra, corners with two equivalent O(3)Ca3Ge tetrahedra,  an edgeedge with one O(2)Ca3Ga tetrahedra, and  an edgeedge with one O(3)Ca3Ge tetrahedra. In the second O site, O(2) is bonded to one Ca(2), two equivalent Ca(1), and one Ga(2) atom to form OCa3Ga tetrahedra that share corners with two equivalent O(1)Ca2GaGe tetrahedra, corners with two equivalent O(2)Ca3Ga tetrahedra, corners with two equivalent O(3)Ca3Ge tetrahedra,  an edgeedge with one O(1)Ca2GaGe tetrahedra, and  an edgeedge with one O(3)Ca3Ge tetrahedra. In the third O site, O(3) is bonded to one Ca(1), two equivalent Ca(2), and one Ge(1) atom to form distorted OCa3Ge tetrahedra that share corners with two equivalent O(1)Ca2GaGe tetrahedra, corners with two equivalent O(2)Ca3Ga tetrahedra, corners with two equivalent O(3)Ca3Ge tetrahedra,  an edgeedge with one O(1)Ca2GaGe tetrahedra, and  an edgeedge with one O(2)Ca3Ga tetrahedra. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Ca(2), one Ga(1), and one Ge(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Ga(1), and one Ga(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ga(1), and one Ga(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), one Ga(1), and one Ge(1) atom.
Ca2Ga2GeO7 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(6), one O(7), two equivalent O(2), and two equivalent O(5) atoms. The Ca(1)-O(1) bond length is 2.50 Å. The Ca(1)-O(3) bond length is 2.76 Å. The Ca(1)-O(6) bond length is 2.39 Å. The Ca(1)-O(7) bond length is 3.08 Å. There is one shorter (2.46 Å) and one longer (2.57 Å) Ca(1)-O(2) bond length. There is one shorter (2.46 Å) and one longer (2.87 Å) Ca(1)-O(5) bond length. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(6), one O(7), two equivalent O(3), and two equivalent O(4) atoms. The Ca(2)-O(1) bond length is 2.43 Å. The Ca(2)-O(2) bond length is 2.45 Å. The Ca(2)-O(6) bond length is 2.79 Å. The Ca(2)-O(7) bond length is 2.53 Å. There is one shorter (2.57 Å) and one longer (2.65 Å) Ca(2)-O(3) bond length. There is one shorter (2.45 Å) and one longer (3.01 Å) Ca(2)-O(4) bond length. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form GaO4 tetrahedra that share corners with two equivalent Ga(2)O4 tetrahedra and corners with two equivalent Ge(1)O4 tetrahedra. The Ga(1)-O(4) bond length is 1.87 Å. The Ga(1)-O(5) bond length is 1.83 Å. The Ga(1)-O(6) bond length is 1.84 Å. The Ga(1)-O(7) bond length is 1.87 Å. In the second Ga site, Ga(2) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form distorted GaO4 tetrahedra that share  a cornercorner with one Ge(1)O4 tetrahedra and corners with two equivalent Ga(1)O4 tetrahedra. The Ga(2)-O(1) bond length is 1.89 Å. The Ga(2)-O(2) bond length is 1.80 Å. The Ga(2)-O(5) bond length is 1.87 Å. The Ga(2)-O(6) bond length is 1.87 Å. Ge(1) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form GeO4 tetrahedra that share  a cornercorner with one Ga(2)O4 tetrahedra and corners with two equivalent Ga(1)O4 tetrahedra. The Ge(1)-O(1) bond length is 1.78 Å. The Ge(1)-O(3) bond length is 1.73 Å. The Ge(1)-O(4) bond length is 1.79 Å. The Ge(1)-O(7) bond length is 1.79 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(2), one Ga(2), and one Ge(1) atom to form distorted OCa2GaGe tetrahedra that share corners with two equivalent O(2)Ca3Ga tetrahedra, corners with two equivalent O(3)Ca3Ge tetrahedra,  an edgeedge with one O(2)Ca3Ga tetrahedra, and  an edgeedge with one O(3)Ca3Ge tetrahedra. In the second O site, O(2) is bonded to one Ca(2), two equivalent Ca(1), and one Ga(2) atom to form OCa3Ga tetrahedra that share corners with two equivalent O(1)Ca2GaGe tetrahedra, corners with two equivalent O(2)Ca3Ga tetrahedra, corners with two equivalent O(3)Ca3Ge tetrahedra,  an edgeedge with one O(1)Ca2GaGe tetrahedra, and  an edgeedge with one O(3)Ca3Ge tetrahedra. In the third O site, O(3) is bonded to one Ca(1), two equivalent Ca(2), and one Ge(1) atom to form distorted OCa3Ge tetrahedra that share corners with two equivalent O(1)Ca2GaGe tetrahedra, corners with two equivalent O(2)Ca3Ga tetrahedra, corners with two equivalent O(3)Ca3Ge tetrahedra,  an edgeedge with one O(1)Ca2GaGe tetrahedra, and  an edgeedge with one O(2)Ca3Ga tetrahedra. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Ca(2), one Ga(1), and one Ge(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Ga(1), and one Ga(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ga(1), and one Ga(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), one Ga(1), and one Ge(1) atom.