SrCa2I6 is Hydrophilite-derived structured and crystallizes in the monoclinic C2/c space group. Sr(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form distorted SrI6 pentagonal pyramids that share corners with four equivalent Ca(1)I6 octahedra, edges with two equivalent Ca(1)I6 octahedra, and edges with two equivalent Sr(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 40-57°. Ca(1) is bonded to one I(1), two equivalent I(2), and three equivalent I(3) atoms to form CaI6 octahedra that share corners with six equivalent Ca(1)I6 octahedra, corners with two equivalent Sr(1)I6 pentagonal pyramids,  an edgeedge with one Ca(1)I6 octahedra, and  an edgeedge with one Sr(1)I6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 45-62°. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1) and one Ca(1) atom. In the second I site, I(2) is bonded in a trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms. In the third I site, I(3) is bonded in a distorted trigonal planar geometry to three equivalent Ca(1) atoms.
SrCa2I6 is Hydrophilite-derived structured and crystallizes in the monoclinic C2/c space group. Sr(1) is bonded to two equivalent I(2) and four equivalent I(1) atoms to form distorted SrI6 pentagonal pyramids that share corners with four equivalent Ca(1)I6 octahedra, edges with two equivalent Ca(1)I6 octahedra, and edges with two equivalent Sr(1)I6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 40-57°. Both Sr(1)-I(2) bond lengths are 3.48 Å. There are two shorter (3.26 Å) and two longer (3.42 Å) Sr(1)-I(1) bond lengths. Ca(1) is bonded to one I(1), two equivalent I(2), and three equivalent I(3) atoms to form CaI6 octahedra that share corners with six equivalent Ca(1)I6 octahedra, corners with two equivalent Sr(1)I6 pentagonal pyramids,  an edgeedge with one Ca(1)I6 octahedra, and  an edgeedge with one Sr(1)I6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 45-62°. The Ca(1)-I(1) bond length is 3.04 Å. There is one shorter (3.22 Å) and one longer (3.24 Å) Ca(1)-I(2) bond length. There is one shorter (3.11 Å) and two longer (3.25 Å) Ca(1)-I(3) bond lengths. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal planar geometry to two equivalent Sr(1) and one Ca(1) atom. In the second I site, I(2) is bonded in a trigonal planar geometry to one Sr(1) and two equivalent Ca(1) atoms. In the third I site, I(3) is bonded in a distorted trigonal planar geometry to three equivalent Ca(1) atoms.