Na4TaGa(SiO4)3 crystallizes in the trigonal R3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(3) and three equivalent O(4) atoms. Ta(1) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form TaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Ga(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form GaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ga(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-36°. There are four inequivalent O sites. In the first O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Ga(1), and one Si(1) atom to form distorted ONa3GaSi trigonal bipyramids that share corners with six equivalent O(4)Na3TaSi trigonal bipyramids,  an edgeedge with one O(4)Na3TaSi trigonal bipyramid, and faces with two equivalent O(3)Na3GaSi trigonal bipyramids. In the second O site, O(4) is bonded to one Na(2), two equivalent Na(1), one Ta(1), and one Si(1) atom to form distorted ONa3TaSi trigonal bipyramids that share corners with six equivalent O(3)Na3GaSi trigonal bipyramids,  an edgeedge with one O(3)Na3GaSi trigonal bipyramid, and faces with two equivalent O(4)Na3TaSi trigonal bipyramids. In the third O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Na(1), one Ga(1), and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(1), one Ta(1), and one Si(1) atom.
Na4TaGa(SiO4)3 crystallizes in the trigonal R3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There is one shorter (2.56 Å) and one longer (2.90 Å) Na(1)-O(1) bond length. There is one shorter (2.77 Å) and one longer (2.92 Å) Na(1)-O(2) bond length. There is one shorter (2.40 Å) and one longer (2.46 Å) Na(1)-O(3) bond length. There is one shorter (2.51 Å) and one longer (2.61 Å) Na(1)-O(4) bond length. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(3) and three equivalent O(4) atoms. All Na(2)-O(3) bond lengths are 2.44 Å. All Na(2)-O(4) bond lengths are 2.62 Å. Ta(1) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form TaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. All Ta(1)-O(2) bond lengths are 1.96 Å. All Ta(1)-O(4) bond lengths are 2.03 Å. Ga(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form GaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. All Ga(1)-O(1) bond lengths are 1.95 Å. All Ga(1)-O(3) bond lengths are 2.07 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ga(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-36°. The Si(1)-O(1) bond length is 1.61 Å. The Si(1)-O(2) bond length is 1.67 Å. The Si(1)-O(3) bond length is 1.62 Å. The Si(1)-O(4) bond length is 1.67 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Ga(1), and one Si(1) atom to form distorted ONa3GaSi trigonal bipyramids that share corners with six equivalent O(4)Na3TaSi trigonal bipyramids,  an edgeedge with one O(4)Na3TaSi trigonal bipyramid, and faces with two equivalent O(3)Na3GaSi trigonal bipyramids. In the second O site, O(4) is bonded to one Na(2), two equivalent Na(1), one Ta(1), and one Si(1) atom to form distorted ONa3TaSi trigonal bipyramids that share corners with six equivalent O(3)Na3GaSi trigonal bipyramids,  an edgeedge with one O(3)Na3GaSi trigonal bipyramid, and faces with two equivalent O(4)Na3TaSi trigonal bipyramids. In the third O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Na(1), one Ga(1), and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(1), one Ta(1), and one Si(1) atom.