Ca4Cu5O10 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form edge-sharing CaO6 octahedra. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(3) atoms. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. In the third Cu site, Cu(3) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and two equivalent Cu(2) atoms to form distorted OCa2Cu2 trigonal pyramids that share corners with four equivalent O(2)Ca3Cu2 trigonal bipyramids, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids, edges with two equivalent O(2)Ca3Cu2 trigonal bipyramids, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(2), one Cu(2), and one Cu(3) atom to form distorted OCa3Cu2 trigonal bipyramids that share corners with three equivalent O(2)Ca3Cu2 trigonal bipyramids, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids, edges with three equivalent O(2)Ca3Cu2 trigonal bipyramids, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), one Cu(1), and one Cu(3) atom.
Ca4Cu5O10 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Both Ca(1)-O(1) bond lengths are 2.31 Å. Both Ca(1)-O(2) bond lengths are 2.56 Å. There are two shorter (2.35 Å) and two longer (2.90 Å) Ca(1)-O(3) bond lengths. In the second Ca site, Ca(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form edge-sharing CaO6 octahedra. Both Ca(2)-O(3) bond lengths are 2.33 Å. There are two shorter (2.38 Å) and two longer (2.39 Å) Ca(2)-O(2) bond lengths. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Cu(1)-O(3) bond lengths are 1.83 Å. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(2)-O(1) bond lengths are 1.87 Å. Both Cu(2)-O(2) bond lengths are 1.89 Å. In the third Cu site, Cu(3) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Cu(3)-O(2) bond lengths are 1.95 Å. Both Cu(3)-O(3) bond lengths are 1.94 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and two equivalent Cu(2) atoms to form distorted OCa2Cu2 trigonal pyramids that share corners with four equivalent O(2)Ca3Cu2 trigonal bipyramids, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids, edges with two equivalent O(2)Ca3Cu2 trigonal bipyramids, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid. In the second O site, O(2) is bonded to one Ca(1), two equivalent Ca(2), one Cu(2), and one Cu(3) atom to form distorted OCa3Cu2 trigonal bipyramids that share corners with three equivalent O(2)Ca3Cu2 trigonal bipyramids, corners with two equivalent O(1)Ca2Cu2 trigonal pyramids, edges with three equivalent O(2)Ca3Cu2 trigonal bipyramids, and  an edgeedge with one O(1)Ca2Cu2 trigonal pyramid. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), one Cu(1), and one Cu(3) atom.