NaCa2Si3O8(OH) is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 7-coordinate geometry to one H(1), one O(1), one O(2), one O(3), one O(6), one O(8), and one O(9) atom. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(4), one O(7), one O(8), one O(9), and two equivalent O(5) atoms to form CaO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(3)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with three equivalent Ca(2)O6 octahedra. In the second Ca site, Ca(2) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(4) atoms to form CaO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O6 octahedra, and edges with three equivalent Ca(1)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-59°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with three equivalent Ca(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-66°. In the third Si site, Si(3) is bonded to one O(2), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-66°. H(1) is bonded in a distorted linear geometry to one Na(1), one O(6), and one O(9) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Si(2), and one Si(3) atom. In the fourth O site, O(4) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Ca(2), one Si(2), and one H(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(1) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Na(1), one Ca(1), one Si(3), and one H(1) atom.
NaCa2Si3O8(OH) is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 7-coordinate geometry to one H(1), one O(1), one O(2), one O(3), one O(6), one O(8), and one O(9) atom. The Na(1)-H(1) bond length is 2.34 Å. The Na(1)-O(1) bond length is 2.52 Å. The Na(1)-O(2) bond length is 2.57 Å. The Na(1)-O(3) bond length is 2.33 Å. The Na(1)-O(6) bond length is 2.49 Å. The Na(1)-O(8) bond length is 2.32 Å. The Na(1)-O(9) bond length is 2.53 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(4), one O(7), one O(8), one O(9), and two equivalent O(5) atoms to form CaO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(3)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with three equivalent Ca(2)O6 octahedra. The Ca(1)-O(4) bond length is 2.40 Å. The Ca(1)-O(7) bond length is 2.34 Å. The Ca(1)-O(8) bond length is 2.35 Å. The Ca(1)-O(9) bond length is 2.39 Å. There is one shorter (2.40 Å) and one longer (2.46 Å) Ca(1)-O(5) bond length. In the second Ca site, Ca(2) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(4) atoms to form CaO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O6 octahedra, and edges with three equivalent Ca(1)O6 octahedra. The Ca(2)-O(5) bond length is 2.45 Å. The Ca(2)-O(6) bond length is 2.34 Å. The Ca(2)-O(7) bond length is 2.34 Å. The Ca(2)-O(8) bond length is 2.34 Å. There is one shorter (2.39 Å) and one longer (2.46 Å) Ca(2)-O(4) bond length. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-59°. The Si(1)-O(1) bond length is 1.69 Å. The Si(1)-O(2) bond length is 1.69 Å. The Si(1)-O(7) bond length is 1.61 Å. The Si(1)-O(8) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with three equivalent Ca(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-66°. The Si(2)-O(1) bond length is 1.68 Å. The Si(2)-O(3) bond length is 1.67 Å. The Si(2)-O(4) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.62 Å. In the third Si site, Si(3) is bonded to one O(2), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-66°. The Si(3)-O(2) bond length is 1.66 Å. The Si(3)-O(3) bond length is 1.64 Å. The Si(3)-O(5) bond length is 1.62 Å. The Si(3)-O(9) bond length is 1.65 Å. H(1) is bonded in a distorted linear geometry to one Na(1), one O(6), and one O(9) atom. The H(1)-O(6) bond length is 1.44 Å. The H(1)-O(9) bond length is 1.07 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Si(2), and one Si(3) atom. In the fourth O site, O(4) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Ca(2), one Si(2), and one H(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(1) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Na(1), one Ca(1), one Si(3), and one H(1) atom.