Sr4CaMn2(GaO5)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), and two equivalent O(4) atoms. Ca(1) is bonded in a distorted square co-planar geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Ga(1)O4 tetrahedra. In the second Mn site, Mn(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Ga(1) is bonded to one O(3), one O(4), and two equivalent O(5) atoms to form GaO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and  an edgeedge with one Ga(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Sr(1), one Sr(2), one Ca(1), one Mn(1), and one Mn(2) atom to form OSr2CaMn2 trigonal bipyramids that share corners with two equivalent O(5)Sr2Ga2 tetrahedra, corners with three equivalent O(1)Sr2CaMn2 trigonal bipyramids,  a cornercorner with one O(4)Sr3Ga trigonal pyramid, and  an edgeedge with one O(4)Sr3Ga trigonal pyramid. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Ca(1), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(2), one Ca(1), one Mn(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded to one Sr(1), two equivalent Sr(2), and one Ga(1) atom to form distorted OSr3Ga trigonal pyramids that share corners with three equivalent O(5)Sr2Ga2 tetrahedra,  a cornercorner with one O(1)Sr2CaMn2 trigonal bipyramid,  an edgeedge with one O(5)Sr2Ga2 tetrahedra,  an edgeedge with one O(1)Sr2CaMn2 trigonal bipyramid, and  an edgeedge with one O(4)Sr3Ga trigonal pyramid. In the fifth O site, O(5) is bonded to one Sr(1), one Sr(2), and two equivalent Ga(1) atoms to form distorted OSr2Ga2 tetrahedra that share corners with two equivalent O(1)Sr2CaMn2 trigonal bipyramids, corners with three equivalent O(4)Sr3Ga trigonal pyramids,  an edgeedge with one O(5)Sr2Ga2 tetrahedra, and  an edgeedge with one O(4)Sr3Ga trigonal pyramid.
Sr4CaMn2(GaO5)2 crystallizes in the triclinic P-1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and two equivalent O(2) atoms. The Sr(1)-O(1) bond length is 2.58 Å. The Sr(1)-O(3) bond length is 2.77 Å. The Sr(1)-O(4) bond length is 2.46 Å. The Sr(1)-O(5) bond length is 2.65 Å. There is one shorter (2.44 Å) and one longer (2.63 Å) Sr(1)-O(2) bond length. In the second Sr site, Sr(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(5), and two equivalent O(4) atoms. The Sr(2)-O(1) bond length is 2.54 Å. The Sr(2)-O(3) bond length is 2.77 Å. The Sr(2)-O(5) bond length is 2.50 Å. There is one shorter (2.43 Å) and one longer (2.45 Å) Sr(2)-O(4) bond length. Ca(1) is bonded in a distorted square co-planar geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both Ca(1)-O(1) bond lengths are 2.25 Å. Both Ca(1)-O(2) bond lengths are 2.25 Å. Both Ca(1)-O(3) bond lengths are 2.95 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Ga(1)O4 tetrahedra. Both Mn(1)-O(1) bond lengths are 2.21 Å. Both Mn(1)-O(2) bond lengths are 2.33 Å. Both Mn(1)-O(3) bond lengths are 2.34 Å. In the second Mn site, Mn(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Mn(2)-O(1) bond lengths are 2.04 Å. Both Mn(2)-O(2) bond lengths are 2.36 Å. Ga(1) is bonded to one O(3), one O(4), and two equivalent O(5) atoms to form GaO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and  an edgeedge with one Ga(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. The Ga(1)-O(3) bond length is 1.86 Å. The Ga(1)-O(4) bond length is 1.83 Å. There is one shorter (1.91 Å) and one longer (1.94 Å) Ga(1)-O(5) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Sr(1), one Sr(2), one Ca(1), one Mn(1), and one Mn(2) atom to form OSr2CaMn2 trigonal bipyramids that share corners with two equivalent O(5)Sr2Ga2 tetrahedra, corners with three equivalent O(1)Sr2CaMn2 trigonal bipyramids,  a cornercorner with one O(4)Sr3Ga trigonal pyramid, and  an edgeedge with one O(4)Sr3Ga trigonal pyramid. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Sr(1), one Ca(1), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Sr(1), one Sr(2), one Ca(1), one Mn(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded to one Sr(1), two equivalent Sr(2), and one Ga(1) atom to form distorted OSr3Ga trigonal pyramids that share corners with three equivalent O(5)Sr2Ga2 tetrahedra,  a cornercorner with one O(1)Sr2CaMn2 trigonal bipyramid,  an edgeedge with one O(5)Sr2Ga2 tetrahedra,  an edgeedge with one O(1)Sr2CaMn2 trigonal bipyramid, and  an edgeedge with one O(4)Sr3Ga trigonal pyramid. In the fifth O site, O(5) is bonded to one Sr(1), one Sr(2), and two equivalent Ga(1) atoms to form distorted OSr2Ga2 tetrahedra that share corners with two equivalent O(1)Sr2CaMn2 trigonal bipyramids, corners with three equivalent O(4)Sr3Ga trigonal pyramids,  an edgeedge with one O(5)Sr2Ga2 tetrahedra, and  an edgeedge with one O(4)Sr3Ga trigonal pyramid.