CsMg14Y crystallizes in the orthorhombic Amm2 space group. Cs(1) is bonded to two equivalent Mg(7); four Mg(3,3,3); four Mg(5,5); and two equivalent Y(1) atoms to form CsY2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Cs(1)Y2Mg10 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra; edges with four equivalent Mg(7)CsMg11 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Y(1)Cs2Mg10 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; and faces with six equivalent Mg(6)YMg11 cuboctahedra. There are ten inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cs(1)Y2Mg10 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(6)YMg11 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with two equivalent Y(1)Cs2Mg10 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; and faces with six equivalent Mg(7)CsMg11 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Y(1)Cs2Mg10 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(7)CsMg11 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Cs(1)Y2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; and faces with six equivalent Mg(6)YMg11 cuboctahedra. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Cs(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Y(1) atoms. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cs(1)Y2Mg10 cuboctahedra; corners with four equivalent Y(1)Cs2Mg10 cuboctahedra; corners with six equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(7)CsMg11 cuboctahedra; edges with four Mg(5,5)CsYMg10 cuboctahedra; edges with four equivalent Mg(6)YMg11 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; and faces with eight Mg(5,5)CsYMg10 cuboctahedra. In the fifth Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Cs(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Y(1) atoms. In the sixth Mg site, Mg(5) is bonded to one Cs(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Y(1) atom to form distorted MgCsYMg10 cuboctahedra that share corners with four equivalent Mg(7)CsMg11 cuboctahedra; corners with four equivalent Mg(6)YMg11 cuboctahedra; corners with ten Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with two equivalent Mg(7)CsMg11 cuboctahedra; edges with two equivalent Mg(5)CsYMg10 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(6)YMg11 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra;  a faceface with one Cs(1)Y2Mg10 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Y(1)Cs2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with four equivalent Mg(5)CsYMg10 cuboctahedra; and faces with four equivalent Mg(4)Mg12 cuboctahedra. In the seventh Mg site, Mg(6) is bonded to one Mg(1); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(7); four Mg(5,5); and one Y(1) atom to form MgYMg11 cuboctahedra that share corners with four equivalent Mg(7)CsMg11 cuboctahedra; corners with six equivalent Mg(6)YMg11 cuboctahedra; corners with eight Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Mg(7)CsMg11 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra; edges with four Mg(5,5)CsYMg10 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Y(1)Cs2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with three equivalent Cs(1)Y2Mg10 cuboctahedra; faces with three equivalent Mg(2)Mg12 cuboctahedra; and faces with four Mg(5,5)CsYMg10 cuboctahedra. In the eighth Mg site, Mg(7) is bonded to one Cs(1); one Mg(2); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(6); and four Mg(5,5) atoms to form distorted MgCsMg11 cuboctahedra that share corners with four equivalent Mg(6)YMg11 cuboctahedra; corners with six equivalent Mg(7)CsMg11 cuboctahedra; corners with eight Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(6)YMg11 cuboctahedra; edges with four Mg(5,5)CsYMg10 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra;  a faceface with one Cs(1)Y2Mg10 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; faces with three equivalent Y(1)Cs2Mg10 cuboctahedra; and faces with four Mg(5,5)CsYMg10 cuboctahedra. In the ninth Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Cs(1); two equivalent Mg(3); two Mg(5,5); two equivalent Mg(6); two equivalent Mg(7); and two equivalent Y(1) atoms. In the tenth Mg site, Mg(5) is bonded to one Cs(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Y(1) atom to form distorted MgCsYMg10 cuboctahedra that share corners with four equivalent Mg(7)CsMg11 cuboctahedra; corners with four equivalent Mg(6)YMg11 cuboctahedra; corners with ten Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with two equivalent Mg(7)CsMg11 cuboctahedra; edges with two equivalent Mg(5)CsYMg10 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(6)YMg11 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra;  a faceface with one Cs(1)Y2Mg10 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Y(1)Cs2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with four equivalent Mg(5)CsYMg10 cuboctahedra; and faces with four equivalent Mg(4)Mg12 cuboctahedra. Y(1) is bonded to two equivalent Cs(1); two equivalent Mg(6); four Mg(3,3,3); and four Mg(5,5) atoms to form YCs2Mg10 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Y(1)Cs2Mg10 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with four equivalent Mg(6)YMg11 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Cs(1)Y2Mg10 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; and faces with six equivalent Mg(7)CsMg11 cuboctahedra.
CsMg14Y crystallizes in the orthorhombic Amm2 space group. Cs(1) is bonded to two equivalent Mg(7); four Mg(3,3,3); four Mg(5,5); and two equivalent Y(1) atoms to form CsY2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Cs(1)Y2Mg10 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra; edges with four equivalent Mg(7)CsMg11 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Y(1)Cs2Mg10 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; and faces with six equivalent Mg(6)YMg11 cuboctahedra. Both Cs(1)-Mg(7) bond lengths are 3.49 Å. There are two shorter (3.32 Å) and two longer (3.33 Å) Cs(1)-Mg(3,3,3) bond lengths. All Cs(1)-Mg(5,5) bond lengths are 3.52 Å. Both Cs(1)-Y(1) bond lengths are 3.34 Å. There are ten inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cs(1)Y2Mg10 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(6)YMg11 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with two equivalent Y(1)Cs2Mg10 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; and faces with six equivalent Mg(7)CsMg11 cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.34 Å. Both Mg(1)-Mg(6) bond lengths are 3.29 Å. There are two shorter (3.29 Å) and two longer (3.37 Å) Mg(1)-Mg(4) bond lengths. All Mg(1)-Mg(5,5) bond lengths are 3.13 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Y(1)Cs2Mg10 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(7)CsMg11 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Cs(1)Y2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; and faces with six equivalent Mg(6)YMg11 cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.22 Å. There are two shorter (3.32 Å) and two longer (3.34 Å) Mg(2)-Mg(4) bond lengths. All Mg(2)-Mg(5,5) bond lengths are 3.19 Å. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Cs(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Y(1) atoms. There is one shorter (3.29 Å) and one longer (3.38 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mg(5) bond lengths are 3.45 Å. Both Mg(3)-Mg(6) bond lengths are 3.29 Å. Both Mg(3)-Mg(7) bond lengths are 3.43 Å. There is one shorter (3.26 Å) and one longer (3.40 Å) Mg(3)-Y(1) bond length. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cs(1)Y2Mg10 cuboctahedra; corners with four equivalent Y(1)Cs2Mg10 cuboctahedra; corners with six equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(7)CsMg11 cuboctahedra; edges with four Mg(5,5)CsYMg10 cuboctahedra; edges with four equivalent Mg(6)YMg11 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; and faces with eight Mg(5,5)CsYMg10 cuboctahedra. There is one shorter (3.31 Å) and one longer (3.36 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.12 Å. Both Mg(4)-Mg(6) bond lengths are 3.29 Å. Both Mg(4)-Mg(7) bond lengths are 3.14 Å. In the fifth Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Cs(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Y(1) atoms. There is one shorter (3.29 Å) and one longer (3.38 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mg(5) bond lengths are 3.45 Å. Both Mg(3)-Mg(6) bond lengths are 3.29 Å. Both Mg(3)-Mg(7) bond lengths are 3.43 Å. There is one shorter (3.26 Å) and one longer (3.40 Å) Mg(3)-Y(1) bond length. In the sixth Mg site, Mg(5) is bonded to one Cs(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Y(1) atom to form distorted MgCsYMg10 cuboctahedra that share corners with four equivalent Mg(7)CsMg11 cuboctahedra; corners with four equivalent Mg(6)YMg11 cuboctahedra; corners with ten Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with two equivalent Mg(7)CsMg11 cuboctahedra; edges with two equivalent Mg(5)CsYMg10 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(6)YMg11 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra;  a faceface with one Cs(1)Y2Mg10 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Y(1)Cs2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with four equivalent Mg(5)CsYMg10 cuboctahedra; and faces with four equivalent Mg(4)Mg12 cuboctahedra. There is one shorter (3.20 Å) and one longer (3.47 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.33 Å) and one longer (3.34 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.18 Å) and one longer (3.48 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Y(1) bond length is 3.42 Å. In the seventh Mg site, Mg(6) is bonded to one Mg(1); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(7); four Mg(5,5); and one Y(1) atom to form MgYMg11 cuboctahedra that share corners with four equivalent Mg(7)CsMg11 cuboctahedra; corners with six equivalent Mg(6)YMg11 cuboctahedra; corners with eight Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Mg(7)CsMg11 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra; edges with four Mg(5,5)CsYMg10 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Y(1)Cs2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with three equivalent Cs(1)Y2Mg10 cuboctahedra; faces with three equivalent Mg(2)Mg12 cuboctahedra; and faces with four Mg(5,5)CsYMg10 cuboctahedra. The Mg(6)-Mg(3) bond length is 3.29 Å. Both Mg(6)-Mg(7) bond lengths are 3.34 Å. The Mg(6)-Mg(5) bond length is 3.33 Å. The Mg(6)-Y(1) bond length is 3.36 Å. In the eighth Mg site, Mg(7) is bonded to one Cs(1); one Mg(2); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(6); and four Mg(5,5) atoms to form distorted MgCsMg11 cuboctahedra that share corners with four equivalent Mg(6)YMg11 cuboctahedra; corners with six equivalent Mg(7)CsMg11 cuboctahedra; corners with eight Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(6)YMg11 cuboctahedra; edges with four Mg(5,5)CsYMg10 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra;  a faceface with one Cs(1)Y2Mg10 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; faces with three equivalent Y(1)Cs2Mg10 cuboctahedra; and faces with four Mg(5,5)CsYMg10 cuboctahedra. The Mg(7)-Mg(3) bond length is 3.43 Å. The Mg(7)-Mg(5) bond length is 3.48 Å. In the ninth Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Cs(1); two equivalent Mg(3); two Mg(5,5); two equivalent Mg(6); two equivalent Mg(7); and two equivalent Y(1) atoms. Both Mg(3)-Mg(5,5) bond lengths are 3.45 Å. There is one shorter (3.26 Å) and one longer (3.40 Å) Mg(3)-Y(1) bond length. In the tenth Mg site, Mg(5) is bonded to one Cs(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Y(1) atom to form distorted MgCsYMg10 cuboctahedra that share corners with four equivalent Mg(7)CsMg11 cuboctahedra; corners with four equivalent Mg(6)YMg11 cuboctahedra; corners with ten Mg(5,5)CsYMg10 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with two equivalent Mg(7)CsMg11 cuboctahedra; edges with two equivalent Mg(5)CsYMg10 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(6)YMg11 cuboctahedra; edges with two equivalent Y(1)Cs2Mg10 cuboctahedra;  a faceface with one Cs(1)Y2Mg10 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Y(1)Cs2Mg10 cuboctahedra; faces with two equivalent Mg(7)CsMg11 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with four equivalent Mg(5)CsYMg10 cuboctahedra; and faces with four equivalent Mg(4)Mg12 cuboctahedra. The Mg(5)-Mg(3) bond length is 3.45 Å. The Mg(5)-Mg(4) bond length is 3.12 Å. There is one shorter (3.20 Å) and one longer (3.47 Å) Mg(5)-Mg(5) bond length. The Mg(5)-Y(1) bond length is 3.42 Å. Y(1) is bonded to two equivalent Cs(1); two equivalent Mg(6); four Mg(3,3,3); and four Mg(5,5) atoms to form YCs2Mg10 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Y(1)Cs2Mg10 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Cs(1)Y2Mg10 cuboctahedra; edges with four equivalent Mg(6)YMg11 cuboctahedra; edges with eight Mg(5,5)CsYMg10 cuboctahedra; faces with two equivalent Cs(1)Y2Mg10 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(6)YMg11 cuboctahedra; faces with four Mg(5,5)CsYMg10 cuboctahedra; and faces with six equivalent Mg(7)CsMg11 cuboctahedra.