SrCaCr(PO4)2 is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms. Ca(1) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-90°. Cr(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(8) atoms to form distorted CrO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-90°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, and  an edgeedge with one Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-55°. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and  an edgeedge with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-60°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Ca(1), and one P(1) atom to form distorted edge-sharing OSr2CaP trigonal pyramids. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(1), one Cr(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Cr(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Cr(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Sr(1), two equivalent Cr(1), and one P(2) atom.
SrCaCr(PO4)2 is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms. The Sr(1)-O(2) bond length is 2.65 Å. The Sr(1)-O(3) bond length is 2.60 Å. The Sr(1)-O(4) bond length is 2.87 Å. The Sr(1)-O(8) bond length is 2.95 Å. There is one shorter (2.72 Å) and one longer (2.83 Å) Sr(1)-O(1) bond length. There is one shorter (2.53 Å) and one longer (2.62 Å) Sr(1)-O(6) bond length. Ca(1) is bonded to one O(1), one O(2), one O(4), one O(7), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with four equivalent Cr(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-90°. The Ca(1)-O(1) bond length is 2.44 Å. The Ca(1)-O(2) bond length is 2.32 Å. The Ca(1)-O(4) bond length is 2.37 Å. The Ca(1)-O(7) bond length is 2.36 Å. There is one shorter (2.33 Å) and one longer (2.43 Å) Ca(1)-O(5) bond length. Cr(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(8) atoms to form distorted CrO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-90°. The Cr(1)-O(3) bond length is 2.08 Å. The Cr(1)-O(4) bond length is 2.11 Å. The Cr(1)-O(5) bond length is 2.54 Å. The Cr(1)-O(7) bond length is 2.03 Å. There is one shorter (2.08 Å) and one longer (2.61 Å) Cr(1)-O(8) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with two equivalent Cr(1)O6 octahedra, and  an edgeedge with one Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-55°. The P(1)-O(1) bond length is 1.57 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.57 Å. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and  an edgeedge with one Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-60°. The P(2)-O(4) bond length is 1.59 Å. The P(2)-O(5) bond length is 1.56 Å. The P(2)-O(6) bond length is 1.53 Å. The P(2)-O(8) bond length is 1.56 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Ca(1), and one P(1) atom to form distorted edge-sharing OSr2CaP trigonal pyramids. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Cr(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Ca(1), one Cr(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Cr(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Cr(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Sr(1), two equivalent Cr(1), and one P(2) atom.