Ca3Ga2P4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent P(2) and four equivalent P(1) atoms. In the second Ca site, Ca(2) is bonded to two equivalent P(1) and four equivalent P(2) atoms to form distorted CaP6 octahedra that share corners with four equivalent Ga(1)P4 tetrahedra, edges with two equivalent Ca(2)P6 octahedra, and edges with four equivalent Ga(1)P4 tetrahedra. Ga(1) is bonded to two equivalent P(1) and two equivalent P(2) atoms to form distorted GaP4 tetrahedra that share corners with two equivalent Ca(2)P6 octahedra, corners with two equivalent Ga(1)P4 tetrahedra, edges with two equivalent Ca(2)P6 octahedra, and  an edgeedge with one Ga(1)P4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-59°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one Ca(2), four equivalent Ca(1), and two equivalent Ga(1) atoms to form distorted PCa5Ga2 pentagonal bipyramids that share corners with two equivalent P(1)Ca5Ga2 pentagonal bipyramids, corners with four equivalent P(2)Ca4Ga2 pentagonal pyramids, edges with five equivalent P(1)Ca5Ga2 pentagonal bipyramids, edges with six equivalent P(2)Ca4Ga2 pentagonal pyramids, and  a faceface with one P(1)Ca5Ga2 pentagonal bipyramid. In the second P site, P(2) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ga(1) atoms to form distorted PCa4Ga2 pentagonal pyramids that share corners with four equivalent P(1)Ca5Ga2 pentagonal bipyramids, corners with two equivalent P(2)Ca4Ga2 pentagonal pyramids, edges with six equivalent P(1)Ca5Ga2 pentagonal bipyramids, and edges with four equivalent P(2)Ca4Ga2 pentagonal pyramids.
Ca3Ga2P4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent P(2) and four equivalent P(1) atoms. There is one shorter (2.85 Å) and one longer (2.91 Å) Ca(1)-P(2) bond length. There are a spread of Ca(1)-P(1) bond distances ranging from 2.95-3.28 Å. In the second Ca site, Ca(2) is bonded to two equivalent P(1) and four equivalent P(2) atoms to form distorted CaP6 octahedra that share corners with four equivalent Ga(1)P4 tetrahedra, edges with two equivalent Ca(2)P6 octahedra, and edges with four equivalent Ga(1)P4 tetrahedra. Both Ca(2)-P(1) bond lengths are 3.03 Å. There are two shorter (2.83 Å) and two longer (2.94 Å) Ca(2)-P(2) bond lengths. Ga(1) is bonded to two equivalent P(1) and two equivalent P(2) atoms to form distorted GaP4 tetrahedra that share corners with two equivalent Ca(2)P6 octahedra, corners with two equivalent Ga(1)P4 tetrahedra, edges with two equivalent Ca(2)P6 octahedra, and  an edgeedge with one Ga(1)P4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-59°. There is one shorter (2.42 Å) and one longer (2.43 Å) Ga(1)-P(1) bond length. There is one shorter (2.35 Å) and one longer (2.36 Å) Ga(1)-P(2) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one Ca(2), four equivalent Ca(1), and two equivalent Ga(1) atoms to form distorted PCa5Ga2 pentagonal bipyramids that share corners with two equivalent P(1)Ca5Ga2 pentagonal bipyramids, corners with four equivalent P(2)Ca4Ga2 pentagonal pyramids, edges with five equivalent P(1)Ca5Ga2 pentagonal bipyramids, edges with six equivalent P(2)Ca4Ga2 pentagonal pyramids, and  a faceface with one P(1)Ca5Ga2 pentagonal bipyramid. In the second P site, P(2) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Ga(1) atoms to form distorted PCa4Ga2 pentagonal pyramids that share corners with four equivalent P(1)Ca5Ga2 pentagonal bipyramids, corners with two equivalent P(2)Ca4Ga2 pentagonal pyramids, edges with six equivalent P(1)Ca5Ga2 pentagonal bipyramids, and edges with four equivalent P(2)Ca4Ga2 pentagonal pyramids.