SrGa2(SiO4)2 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted SrO7 hexagonal pyramids that share corners with two equivalent Ga(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Ga(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ga(2)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form GaO4 tetrahedra that share corners with three equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Si(2)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. In the second Ga site, Ga(2) is bonded to one O(1), one O(4), one O(6), and one O(8) atom to form GaO4 tetrahedra that share corners with two equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Sr(1)O7 hexagonal pyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Ga(2)O4 tetrahedra, corners with three equivalent Ga(1)O4 tetrahedra, and  an edgeedge with one Sr(1)O7 hexagonal pyramid. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form SiO4 tetrahedra that share corners with three equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Ga(1)O4 tetrahedra, and corners with three equivalent Ga(2)O4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ga(2), and one Si(2) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(1), and one Si(1) atom. In the third O site, O(6) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(2), and one Si(2) atom. In the fourth O site, O(7) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(1), and one Si(1) atom. In the fifth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(2), and one Si(2) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ga(2), and one Si(1) atom. In the seventh O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ga(1) and one Si(2) atom. In the eighth O site, O(3) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ga(1), and one Si(1) atom.
SrGa2(SiO4)2 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted SrO7 hexagonal pyramids that share corners with two equivalent Ga(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Ga(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ga(2)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The Sr(1)-O(1) bond length is 2.62 Å. The Sr(1)-O(3) bond length is 2.61 Å. The Sr(1)-O(4) bond length is 2.57 Å. The Sr(1)-O(5) bond length is 2.59 Å. The Sr(1)-O(6) bond length is 2.63 Å. The Sr(1)-O(7) bond length is 2.69 Å. The Sr(1)-O(8) bond length is 2.64 Å. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form GaO4 tetrahedra that share corners with three equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Si(2)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. The Ga(1)-O(2) bond length is 1.81 Å. The Ga(1)-O(3) bond length is 1.84 Å. The Ga(1)-O(5) bond length is 1.84 Å. The Ga(1)-O(7) bond length is 1.84 Å. In the second Ga site, Ga(2) is bonded to one O(1), one O(4), one O(6), and one O(8) atom to form GaO4 tetrahedra that share corners with two equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Sr(1)O7 hexagonal pyramid. The Ga(2)-O(1) bond length is 1.84 Å. The Ga(2)-O(4) bond length is 1.82 Å. The Ga(2)-O(6) bond length is 1.83 Å. The Ga(2)-O(8) bond length is 1.85 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Ga(2)O4 tetrahedra, corners with three equivalent Ga(1)O4 tetrahedra, and  an edgeedge with one Sr(1)O7 hexagonal pyramid. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(3) bond length is 1.62 Å. The Si(1)-O(5) bond length is 1.63 Å. The Si(1)-O(7) bond length is 1.62 Å. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form SiO4 tetrahedra that share corners with three equivalent Sr(1)O7 hexagonal pyramids,  a cornercorner with one Ga(1)O4 tetrahedra, and corners with three equivalent Ga(2)O4 tetrahedra. The Si(2)-O(2) bond length is 1.61 Å. The Si(2)-O(4) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.64 Å. The Si(2)-O(8) bond length is 1.63 Å. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ga(2), and one Si(2) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(1), and one Si(1) atom. In the third O site, O(6) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(2), and one Si(2) atom. In the fourth O site, O(7) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(1), and one Si(1) atom. In the fifth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), one Ga(2), and one Si(2) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ga(2), and one Si(1) atom. In the seventh O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ga(1) and one Si(2) atom. In the eighth O site, O(3) is bonded in a distorted trigonal planar geometry to one Sr(1), one Ga(1), and one Si(1) atom.