Na6Ca3U2O12 crystallizes in the monoclinic C2 space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent U(1)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-14°. In the second Na site, Na(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms to form distorted NaO6 octahedra that share corners with two equivalent Ca(2)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra, corners with two equivalent U(2)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-16°. In the third Na site, Na(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form NaO6 octahedra that share corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent U(1)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-20°. In the fourth Na site, Na(4) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent U(1)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-20°. In the fifth Na site, Na(5) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with two equivalent Na(6)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra, corners with two equivalent U(2)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-14°. In the sixth Na site, Na(6) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(5)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra, corners with two equivalent U(2)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-22°. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form CaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra,  an edgeedge with one U(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(6)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one U(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-22°. In the third Ca site, Ca(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(5)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra,  an edgeedge with one U(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-14°. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form UO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(4)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the second U site, U(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms to form UO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(5)O6 octahedra, corners with two equivalent Na(6)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, and edges with two equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-10°. There are six inequivalent O sites. In the first O site, O(6) is bonded to one Na(2), one Na(3), one Na(4), one Ca(1), and one U(2) atom to form distorted ONa3CaU square pyramids that share corners with two equivalent O(2)Na3Ca2U octahedra, corners with two equivalent O(1)Na3CaU square pyramids, corners with two equivalent O(3)Na3CaU square pyramids, corners with three equivalent O(6)Na3CaU square pyramids,  an edgeedge with one O(2)Na3Ca2U octahedra, edges with four equivalent O(4)Na3Ca2U octahedra,  an edgeedge with one O(6)Na3CaU square pyramid, and edges with two equivalent O(3)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 9-12°. In the second O site, O(1) is bonded to one Na(1), one Na(4), one Na(6), one Ca(2), and one U(1) atom to form distorted ONa3CaU square pyramids that share corners with two equivalent O(2)Na3Ca2U octahedra, corners with two equivalent O(3)Na3CaU square pyramids, corners with two equivalent O(6)Na3CaU square pyramids, corners with three equivalent O(1)Na3CaU square pyramids,  an edgeedge with one O(2)Na3Ca2U octahedra, edges with four equivalent O(5)Na3Ca2U octahedra,  an edgeedge with one O(1)Na3CaU square pyramid, and edges with two equivalent O(3)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 4-8°. In the third O site, O(2) is bonded to one Na(1), one Na(3), one Na(5), one Ca(1), one Ca(3), and one U(1) atom to form distorted ONa3Ca2U octahedra that share corners with two equivalent O(2)Na3Ca2U octahedra, corners with two equivalent O(1)Na3CaU square pyramids, corners with two equivalent O(6)Na3CaU square pyramids, edges with two equivalent O(2)Na3Ca2U octahedra, edges with four equivalent O(4)Na3Ca2U octahedra, edges with four equivalent O(5)Na3Ca2U octahedra,  an edgeedge with one O(1)Na3CaU square pyramid, and  an edgeedge with one O(6)Na3CaU square pyramid. The corner-sharing octahedral tilt angles range from 6-12°. In the fourth O site, O(3) is bonded to one Na(2), one Na(4), one Na(6), one Ca(2), and one U(2) atom to form ONa3CaU square pyramids that share corners with two equivalent O(4)Na3Ca2U octahedra, corners with two equivalent O(5)Na3Ca2U octahedra,  a cornercorner with one O(3)Na3CaU square pyramid, corners with two equivalent O(1)Na3CaU square pyramids, corners with two equivalent O(6)Na3CaU square pyramids,  an edgeedge with one O(4)Na3Ca2U octahedra,  an edgeedge with one O(5)Na3Ca2U octahedra, edges with two equivalent O(1)Na3CaU square pyramids, edges with two equivalent O(3)Na3CaU square pyramids, and edges with two equivalent O(6)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 3-13°. In the fifth O site, O(4) is bonded to one Na(2), one Na(3), one Na(5), one Ca(1), one Ca(3), and one U(2) atom to form ONa3Ca2U octahedra that share corners with two equivalent O(4)Na3Ca2U octahedra, corners with two equivalent O(5)Na3Ca2U octahedra, corners with two equivalent O(3)Na3CaU square pyramids,  an edgeedge with one O(5)Na3Ca2U octahedra, edges with two equivalent O(4)Na3Ca2U octahedra, edges with four equivalent O(2)Na3Ca2U octahedra,  an edgeedge with one O(3)Na3CaU square pyramid, and edges with four equivalent O(6)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 4-9°. In the sixth O site, O(5) is bonded to one Na(1), one Na(5), one Na(6), one Ca(2), one Ca(3), and one U(1) atom to form distorted ONa3Ca2U octahedra that share corners with two equivalent O(4)Na3Ca2U octahedra, corners with two equivalent O(5)Na3Ca2U octahedra, corners with two equivalent O(3)Na3CaU square pyramids,  an edgeedge with one O(4)Na3Ca2U octahedra, edges with two equivalent O(5)Na3Ca2U octahedra, edges with four equivalent O(2)Na3Ca2U octahedra,  an edgeedge with one O(3)Na3CaU square pyramid, and edges with four equivalent O(1)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 1-9°.
Na6Ca3U2O12 crystallizes in the monoclinic C2 space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent U(1)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-14°. Both Na(1)-O(1) bond lengths are 2.31 Å. Both Na(1)-O(2) bond lengths are 2.44 Å. Both Na(1)-O(5) bond lengths are 2.73 Å. In the second Na site, Na(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms to form distorted NaO6 octahedra that share corners with two equivalent Ca(2)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra, corners with two equivalent U(2)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-16°. Both Na(2)-O(3) bond lengths are 2.43 Å. Both Na(2)-O(4) bond lengths are 2.53 Å. Both Na(2)-O(6) bond lengths are 2.84 Å. In the third Na site, Na(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form NaO6 octahedra that share corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent U(1)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-20°. Both Na(3)-O(2) bond lengths are 2.70 Å. Both Na(3)-O(4) bond lengths are 2.49 Å. Both Na(3)-O(6) bond lengths are 2.38 Å. In the fourth Na site, Na(4) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra, corners with two equivalent U(1)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-20°. Both Na(4)-O(1) bond lengths are 2.68 Å. Both Na(4)-O(3) bond lengths are 2.32 Å. Both Na(4)-O(6) bond lengths are 2.53 Å. In the fifth Na site, Na(5) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with two equivalent Na(6)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra, corners with two equivalent U(2)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-14°. Both Na(5)-O(2) bond lengths are 2.53 Å. Both Na(5)-O(4) bond lengths are 2.55 Å. Both Na(5)-O(5) bond lengths are 2.51 Å. In the sixth Na site, Na(6) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(5)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra, corners with two equivalent U(2)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-22°. Both Na(6)-O(1) bond lengths are 2.58 Å. Both Na(6)-O(3) bond lengths are 2.53 Å. Both Na(6)-O(5) bond lengths are 2.58 Å. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form CaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra,  an edgeedge with one Na(4)O6 octahedra,  an edgeedge with one U(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Ca(3)O6 octahedra, and edges with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Both Ca(1)-O(2) bond lengths are 2.39 Å. Both Ca(1)-O(4) bond lengths are 2.40 Å. Both Ca(1)-O(6) bond lengths are 2.28 Å. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(6)O6 octahedra, corners with two equivalent Ca(3)O6 octahedra,  an edgeedge with one Na(5)O6 octahedra,  an edgeedge with one U(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-22°. Both Ca(2)-O(1) bond lengths are 2.38 Å. Both Ca(2)-O(3) bond lengths are 2.33 Å. Both Ca(2)-O(5) bond lengths are 2.43 Å. In the third Ca site, Ca(3) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(5)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  an edgeedge with one Na(6)O6 octahedra,  an edgeedge with one U(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-14°. Both Ca(3)-O(2) bond lengths are 2.37 Å. Both Ca(3)-O(4) bond lengths are 2.40 Å. Both Ca(3)-O(5) bond lengths are 2.40 Å. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form UO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Na(4)O6 octahedra,  an edgeedge with one Ca(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(5)O6 octahedra, edges with two equivalent Na(6)O6 octahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with two equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. Both U(1)-O(1) bond lengths are 2.05 Å. Both U(1)-O(2) bond lengths are 2.16 Å. Both U(1)-O(5) bond lengths are 2.13 Å. In the second U site, U(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms to form UO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(5)O6 octahedra, corners with two equivalent Na(6)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra,  an edgeedge with one Ca(3)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, and edges with two equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-10°. Both U(2)-O(3) bond lengths are 2.11 Å. Both U(2)-O(4) bond lengths are 2.21 Å. Both U(2)-O(6) bond lengths are 2.05 Å. There are six inequivalent O sites. In the first O site, O(6) is bonded to one Na(2), one Na(3), one Na(4), one Ca(1), and one U(2) atom to form distorted ONa3CaU square pyramids that share corners with two equivalent O(2)Na3Ca2U octahedra, corners with two equivalent O(1)Na3CaU square pyramids, corners with two equivalent O(3)Na3CaU square pyramids, corners with three equivalent O(6)Na3CaU square pyramids,  an edgeedge with one O(2)Na3Ca2U octahedra, edges with four equivalent O(4)Na3Ca2U octahedra,  an edgeedge with one O(6)Na3CaU square pyramid, and edges with two equivalent O(3)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 9-12°. In the second O site, O(1) is bonded to one Na(1), one Na(4), one Na(6), one Ca(2), and one U(1) atom to form distorted ONa3CaU square pyramids that share corners with two equivalent O(2)Na3Ca2U octahedra, corners with two equivalent O(3)Na3CaU square pyramids, corners with two equivalent O(6)Na3CaU square pyramids, corners with three equivalent O(1)Na3CaU square pyramids,  an edgeedge with one O(2)Na3Ca2U octahedra, edges with four equivalent O(5)Na3Ca2U octahedra,  an edgeedge with one O(1)Na3CaU square pyramid, and edges with two equivalent O(3)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 4-8°. In the third O site, O(2) is bonded to one Na(1), one Na(3), one Na(5), one Ca(1), one Ca(3), and one U(1) atom to form distorted ONa3Ca2U octahedra that share corners with two equivalent O(2)Na3Ca2U octahedra, corners with two equivalent O(1)Na3CaU square pyramids, corners with two equivalent O(6)Na3CaU square pyramids, edges with two equivalent O(2)Na3Ca2U octahedra, edges with four equivalent O(4)Na3Ca2U octahedra, edges with four equivalent O(5)Na3Ca2U octahedra,  an edgeedge with one O(1)Na3CaU square pyramid, and  an edgeedge with one O(6)Na3CaU square pyramid. The corner-sharing octahedral tilt angles range from 6-12°. In the fourth O site, O(3) is bonded to one Na(2), one Na(4), one Na(6), one Ca(2), and one U(2) atom to form ONa3CaU square pyramids that share corners with two equivalent O(4)Na3Ca2U octahedra, corners with two equivalent O(5)Na3Ca2U octahedra,  a cornercorner with one O(3)Na3CaU square pyramid, corners with two equivalent O(1)Na3CaU square pyramids, corners with two equivalent O(6)Na3CaU square pyramids,  an edgeedge with one O(4)Na3Ca2U octahedra,  an edgeedge with one O(5)Na3Ca2U octahedra, edges with two equivalent O(1)Na3CaU square pyramids, edges with two equivalent O(3)Na3CaU square pyramids, and edges with two equivalent O(6)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 3-13°. In the fifth O site, O(4) is bonded to one Na(2), one Na(3), one Na(5), one Ca(1), one Ca(3), and one U(2) atom to form ONa3Ca2U octahedra that share corners with two equivalent O(4)Na3Ca2U octahedra, corners with two equivalent O(5)Na3Ca2U octahedra, corners with two equivalent O(3)Na3CaU square pyramids,  an edgeedge with one O(5)Na3Ca2U octahedra, edges with two equivalent O(4)Na3Ca2U octahedra, edges with four equivalent O(2)Na3Ca2U octahedra,  an edgeedge with one O(3)Na3CaU square pyramid, and edges with four equivalent O(6)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 4-9°. In the sixth O site, O(5) is bonded to one Na(1), one Na(5), one Na(6), one Ca(2), one Ca(3), and one U(1) atom to form distorted ONa3Ca2U octahedra that share corners with two equivalent O(4)Na3Ca2U octahedra, corners with two equivalent O(5)Na3Ca2U octahedra, corners with two equivalent O(3)Na3CaU square pyramids,  an edgeedge with one O(4)Na3Ca2U octahedra, edges with two equivalent O(5)Na3Ca2U octahedra, edges with four equivalent O(2)Na3Ca2U octahedra,  an edgeedge with one O(3)Na3CaU square pyramid, and edges with four equivalent O(1)Na3CaU square pyramids. The corner-sharing octahedral tilt angles range from 1-9°.