Mg14NiSiO16 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Si(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the third Mg site, Mg(3) is bonded to one O(5), one O(6), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the fourth Mg site, Mg(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Mg(4)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Si(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-8°. Ni(1) is bonded to two equivalent O(4) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with eight equivalent Mg(2)O6 octahedra. The corner-sharing octahedra are not tilted. Si(1) is bonded to two equivalent O(6) and four equivalent O(2) atoms to form SiO6 octahedra that share corners with two equivalent Si(1)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(4), and one Ni(1) atom to form OMg5Ni octahedra that share corners with two equivalent O(2)Mg5Si octahedra, corners with four equivalent O(1)Mg5Ni octahedra, edges with two equivalent O(4)Mg4Ni2 octahedra, edges with two equivalent O(1)Mg5Ni octahedra, edges with two equivalent O(2)Mg5Si octahedra, edges with two equivalent O(5)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the second O site, O(2) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), and one Si(1) atom to form OMg5Si octahedra that share corners with two equivalent O(1)Mg5Ni octahedra, corners with four equivalent O(2)Mg5Si octahedra, edges with two equivalent O(6)Mg4Si2 octahedra, edges with two equivalent O(1)Mg5Ni octahedra, edges with two equivalent O(2)Mg5Si octahedra, edges with two equivalent O(5)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(3) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent Mg(4) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(4)Mg4Ni2 octahedra,  an edgeedge with one O(6)Mg4Si2 octahedra, edges with two equivalent O(5)Mg6 octahedra, edges with four equivalent O(1)Mg5Ni octahedra, and edges with four equivalent O(2)Mg5Si octahedra. The corner-sharing octahedral tilt angles range from 2-4°. In the fourth O site, O(4) is bonded to four equivalent Mg(2) and two equivalent Ni(1) atoms to form OMg4Ni2 octahedra that share corners with two equivalent O(4)Mg4Ni2 octahedra, corners with four equivalent O(5)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with eight equivalent O(1)Mg5Ni octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Mg(3) atoms to form OMg6 octahedra that share corners with two equivalent O(4)Mg4Ni2 octahedra, corners with two equivalent O(6)Mg4Si2 octahedra, corners with two equivalent O(5)Mg6 octahedra, edges with four equivalent O(1)Mg5Ni octahedra, edges with four equivalent O(2)Mg5Si octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the sixth O site, O(6) is bonded to four equivalent Mg(3) and two equivalent Si(1) atoms to form OMg4Si2 octahedra that share corners with two equivalent O(6)Mg4Si2 octahedra, corners with four equivalent O(5)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with eight equivalent O(2)Mg5Si octahedra. The corner-sharing octahedra are not tilted.
Mg14NiSiO16 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, corners with two equivalent Si(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, edges with four equivalent Mg(3)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(1) bond lengths are 2.04 Å. Both Mg(1)-O(2) bond lengths are 2.19 Å. Both Mg(1)-O(5) bond lengths are 2.13 Å. In the second Mg site, Mg(2) is bonded to one O(4), one O(5), two equivalent O(1), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. The Mg(2)-O(4) bond length is 2.11 Å. The Mg(2)-O(5) bond length is 2.17 Å. Both Mg(2)-O(1) bond lengths are 2.13 Å. Both Mg(2)-O(3) bond lengths are 2.15 Å. In the third Mg site, Mg(3) is bonded to one O(5), one O(6), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(3)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, edges with two equivalent Si(1)O6 octahedra, and edges with four equivalent Mg(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. The Mg(3)-O(5) bond length is 2.11 Å. The Mg(3)-O(6) bond length is 2.18 Å. Both Mg(3)-O(2) bond lengths are 2.13 Å. Both Mg(3)-O(3) bond lengths are 2.13 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Mg(4)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Si(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-8°. Both Mg(4)-O(1) bond lengths are 2.10 Å. Both Mg(4)-O(2) bond lengths are 2.19 Å. Both Mg(4)-O(3) bond lengths are 2.13 Å. Ni(1) is bonded to two equivalent O(4) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with eight equivalent Mg(2)O6 octahedra. The corner-sharing octahedra are not tilted. Both Ni(1)-O(4) bond lengths are 2.13 Å. All Ni(1)-O(1) bond lengths are 2.25 Å. Si(1) is bonded to two equivalent O(6) and four equivalent O(2) atoms to form SiO6 octahedra that share corners with two equivalent Si(1)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Mg(4)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Si(1)-O(6) bond lengths are 2.13 Å. All Si(1)-O(2) bond lengths are 2.10 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(4), and one Ni(1) atom to form OMg5Ni octahedra that share corners with two equivalent O(2)Mg5Si octahedra, corners with four equivalent O(1)Mg5Ni octahedra, edges with two equivalent O(4)Mg4Ni2 octahedra, edges with two equivalent O(1)Mg5Ni octahedra, edges with two equivalent O(2)Mg5Si octahedra, edges with two equivalent O(5)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the second O site, O(2) is bonded to one Mg(1), two equivalent Mg(3), two equivalent Mg(4), and one Si(1) atom to form OMg5Si octahedra that share corners with two equivalent O(1)Mg5Ni octahedra, corners with four equivalent O(2)Mg5Si octahedra, edges with two equivalent O(6)Mg4Si2 octahedra, edges with two equivalent O(1)Mg5Ni octahedra, edges with two equivalent O(2)Mg5Si octahedra, edges with two equivalent O(5)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(3) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent Mg(4) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(4)Mg4Ni2 octahedra,  an edgeedge with one O(6)Mg4Si2 octahedra, edges with two equivalent O(5)Mg6 octahedra, edges with four equivalent O(1)Mg5Ni octahedra, and edges with four equivalent O(2)Mg5Si octahedra. The corner-sharing octahedral tilt angles range from 2-4°. In the fourth O site, O(4) is bonded to four equivalent Mg(2) and two equivalent Ni(1) atoms to form OMg4Ni2 octahedra that share corners with two equivalent O(4)Mg4Ni2 octahedra, corners with four equivalent O(5)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with eight equivalent O(1)Mg5Ni octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Mg(3) atoms to form OMg6 octahedra that share corners with two equivalent O(4)Mg4Ni2 octahedra, corners with two equivalent O(6)Mg4Si2 octahedra, corners with two equivalent O(5)Mg6 octahedra, edges with four equivalent O(1)Mg5Ni octahedra, edges with four equivalent O(2)Mg5Si octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the sixth O site, O(6) is bonded to four equivalent Mg(3) and two equivalent Si(1) atoms to form OMg4Si2 octahedra that share corners with two equivalent O(6)Mg4Si2 octahedra, corners with four equivalent O(5)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with eight equivalent O(2)Mg5Si octahedra. The corner-sharing octahedra are not tilted.