CaAsO4 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(4), one O(6), one O(8), and two equivalent O(2) atoms to form distorted CaO6 octahedra that share corners with two equivalent As(2)O4 tetrahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Ca(1)O6 octahedra. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(2), one O(4), one O(5), one O(6), one O(7), one O(8), and two equivalent O(3) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 36-63°. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-67°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ca(1) and one As(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ca(2) and one As(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ca(2) and one As(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ca(2) and one As(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one As(2) atom.
CaAsO4 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(4), one O(6), one O(8), and two equivalent O(2) atoms to form distorted CaO6 octahedra that share corners with two equivalent As(2)O4 tetrahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one Ca(1)O6 octahedra. The Ca(1)-O(1) bond length is 2.36 Å. The Ca(1)-O(4) bond length is 2.32 Å. The Ca(1)-O(6) bond length is 2.42 Å. The Ca(1)-O(8) bond length is 2.40 Å. There is one shorter (2.35 Å) and one longer (2.45 Å) Ca(1)-O(2) bond length. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(2), one O(4), one O(5), one O(6), one O(7), one O(8), and two equivalent O(3) atoms. The Ca(2)-O(2) bond length is 2.60 Å. The Ca(2)-O(4) bond length is 2.71 Å. The Ca(2)-O(5) bond length is 2.44 Å. The Ca(2)-O(6) bond length is 2.46 Å. The Ca(2)-O(7) bond length is 2.56 Å. The Ca(2)-O(8) bond length is 2.46 Å. There is one shorter (2.40 Å) and one longer (2.43 Å) Ca(2)-O(3) bond length. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 36-63°. The As(1)-O(1) bond length is 1.73 Å. The As(1)-O(2) bond length is 1.72 Å. The As(1)-O(3) bond length is 1.71 Å. The As(1)-O(4) bond length is 1.71 Å. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-67°. The As(2)-O(5) bond length is 1.73 Å. The As(2)-O(6) bond length is 1.71 Å. The As(2)-O(7) bond length is 1.75 Å. The As(2)-O(8) bond length is 1.71 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ca(1) and one As(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ca(2) and one As(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ca(2) and one As(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one As(2) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ca(2) and one As(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one As(2) atom.