CaMn2O4 crystallizes in the triclinic P-1 space group. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with ten equivalent Mn(1)O5 square pyramids, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent Mn(1)O5 square pyramids. Mn(1) is bonded to two equivalent O(2) and three equivalent O(1) atoms to form distorted MnO5 square pyramids that share corners with five equivalent Ca(1)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids,  an edgeedge with one Ca(1)O6 octahedra, and edges with three equivalent Mn(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 43-62°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1) and three equivalent Mn(1) atoms to form a mixture of corner and edge-sharing OCaMn3 trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Mn(1) atoms.
CaMn2O4 crystallizes in the triclinic P-1 space group. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with ten equivalent Mn(1)O5 square pyramids, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent Mn(1)O5 square pyramids. Both Ca(1)-O(1) bond lengths are 2.42 Å. There are two shorter (2.35 Å) and two longer (2.37 Å) Ca(1)-O(2) bond lengths. Mn(1) is bonded to two equivalent O(2) and three equivalent O(1) atoms to form distorted MnO5 square pyramids that share corners with five equivalent Ca(1)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids,  an edgeedge with one Ca(1)O6 octahedra, and edges with three equivalent Mn(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 43-62°. There is one shorter (1.89 Å) and one longer (1.95 Å) Mn(1)-O(2) bond length. There are a spread of Mn(1)-O(1) bond distances ranging from 1.92-2.19 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1) and three equivalent Mn(1) atoms to form a mixture of corner and edge-sharing OCaMn3 trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Mn(1) atoms.