The synthetic gallosilicate TsG-1 with the CGS framework topology has been synthesized under hydrothermal conditions and characterized via single-crystal synchrotron X-ray diffraction. Unlike the cobalt−gallium phosphate analogue, this material shows the ideal topological symmetry of Pnma (a = 8.613(2) Å, b = 13.813(3) Å, c = 16.330(3) Å), and extraframework cations are distributed over the buckled 8-ring sites of the interpenetrated double 6-rings as well as along the channels of the s-shaped 10-rings and elliptical 8-rings.