Ca10(PO4)6O crystallizes in the trigonal P3 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 9-coordinate geometry to three equivalent O(3), three equivalent O(6), and three equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent O(4), three equivalent O(5), and three equivalent O(8) atoms. In the third Ca site, Ca(3) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(5), and three equivalent O(8) atoms. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to three equivalent O(6) and three equivalent O(7) atoms. In the fifth Ca site, Ca(5) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(7), and one O(9) atom. In the sixth Ca site, Ca(6) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form distorted CaO6 pentagonal pyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ca(6)O6 pentagonal pyramids. In the second P site, P(2) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(6)O6 pentagonal pyramids and  an edgeedge with one Ca(6)O6 pentagonal pyramid. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(4), one Ca(5), and one P(1) atom. In the second O site, O(8) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Ca(6), and one P(2) atom. In the third O site, O(9) is bonded in a trigonal planar geometry to three equivalent Ca(5) atoms. In the fourth O site, O(1) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(5), one Ca(6), and one P(1) atom. In the fifth O site, O(2) is bonded in a 1-coordinate geometry to one Ca(5), one Ca(6), and one P(2) atom. In the sixth O site, O(3) is bonded in a 1-coordinate geometry to one Ca(1), one Ca(5), one Ca(6), and one P(2) atom. In the seventh O site, O(4) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(5), one Ca(6), and one P(1) atom. In the eighth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Ca(5), and one P(1) atom. In the ninth O site, O(6) is bonded to one Ca(1), one Ca(4), one Ca(6), and one P(2) atom to form distorted edge-sharing OCa3P tetrahedra.
Ca10(PO4)6O crystallizes in the trigonal P3 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 9-coordinate geometry to three equivalent O(3), three equivalent O(6), and three equivalent O(7) atoms. All Ca(1)-O(3) bond lengths are 2.94 Å. All Ca(1)-O(6) bond lengths are 2.48 Å. All Ca(1)-O(7) bond lengths are 2.39 Å. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to three equivalent O(4), three equivalent O(5), and three equivalent O(8) atoms. All Ca(2)-O(4) bond lengths are 2.83 Å. All Ca(2)-O(5) bond lengths are 2.44 Å. All Ca(2)-O(8) bond lengths are 2.46 Å. In the third Ca site, Ca(3) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(5), and three equivalent O(8) atoms. All Ca(3)-O(1) bond lengths are 2.75 Å. All Ca(3)-O(5) bond lengths are 2.48 Å. All Ca(3)-O(8) bond lengths are 2.49 Å. In the fourth Ca site, Ca(4) is bonded in a 6-coordinate geometry to three equivalent O(6) and three equivalent O(7) atoms. All Ca(4)-O(6) bond lengths are 2.45 Å. All Ca(4)-O(7) bond lengths are 2.38 Å. In the fifth Ca site, Ca(5) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(7), and one O(9) atom. The Ca(5)-O(1) bond length is 2.54 Å. The Ca(5)-O(2) bond length is 2.40 Å. The Ca(5)-O(3) bond length is 2.39 Å. The Ca(5)-O(4) bond length is 2.52 Å. The Ca(5)-O(5) bond length is 2.51 Å. The Ca(5)-O(7) bond length is 2.97 Å. The Ca(5)-O(9) bond length is 2.18 Å. In the sixth Ca site, Ca(6) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form distorted CaO6 pentagonal pyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The Ca(6)-O(1) bond length is 2.32 Å. The Ca(6)-O(2) bond length is 2.48 Å. The Ca(6)-O(3) bond length is 2.49 Å. The Ca(6)-O(4) bond length is 2.31 Å. The Ca(6)-O(6) bond length is 2.29 Å. The Ca(6)-O(8) bond length is 2.74 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ca(6)O6 pentagonal pyramids. The P(1)-O(1) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.56 Å. The P(1)-O(7) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(6)O6 pentagonal pyramids and  an edgeedge with one Ca(6)O6 pentagonal pyramid. The P(2)-O(2) bond length is 1.55 Å. The P(2)-O(3) bond length is 1.55 Å. The P(2)-O(6) bond length is 1.57 Å. The P(2)-O(8) bond length is 1.56 Å. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(4), one Ca(5), and one P(1) atom. In the second O site, O(8) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Ca(6), and one P(2) atom. In the third O site, O(9) is bonded in a trigonal planar geometry to three equivalent Ca(5) atoms. In the fourth O site, O(1) is bonded in a 4-coordinate geometry to one Ca(3), one Ca(5), one Ca(6), and one P(1) atom. In the fifth O site, O(2) is bonded in a 1-coordinate geometry to one Ca(5), one Ca(6), and one P(2) atom. In the sixth O site, O(3) is bonded in a 1-coordinate geometry to one Ca(1), one Ca(5), one Ca(6), and one P(2) atom. In the seventh O site, O(4) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(5), one Ca(6), and one P(1) atom. In the eighth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), one Ca(5), and one P(1) atom. In the ninth O site, O(6) is bonded to one Ca(1), one Ca(4), one Ca(6), and one P(2) atom to form distorted edge-sharing OCa3P tetrahedra.