Mg14CrSi crystallizes in the hexagonal P-6m2 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Cr(1)Mg12 cuboctahedra, corners with six equivalent Mg(1)Mg10Si2 cuboctahedra, corners with eight equivalent Mg(2)Mg10Cr2 cuboctahedra, edges with two equivalent Si(1)Mg12 cuboctahedra, edges with four equivalent Mg(1)Mg10Si2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(3)Mg10CrSi cuboctahedra, faces with two equivalent Mg(2)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Si(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Mg10Si2 cuboctahedra, and faces with ten equivalent Mg(3)Mg10CrSi cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(2), four equivalent Mg(3), and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra, corners with six equivalent Mg(2)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Mg10Si2 cuboctahedra, edges with two equivalent Cr(1)Mg12 cuboctahedra, edges with four equivalent Mg(2)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(3)Mg10CrSi cuboctahedra, faces with two equivalent Mg(1)Mg10Si2 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Cr(1)Mg12 cuboctahedra, faces with four equivalent Mg(2)Mg10Cr2 cuboctahedra, and faces with ten equivalent Mg(3)Mg10CrSi cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(2,2); four equivalent Mg(3); and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Mg10Cr2 cuboctahedra; corners with eight equivalent Mg(1)Mg10Si2 cuboctahedra; edges with two equivalent Cr(1)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight equivalent Mg(3)Mg10CrSi cuboctahedra; faces with two equivalent Mg(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Cr(1)Mg12 cuboctahedra; faces with four Mg(2,2)Mg10Cr2 cuboctahedra; and faces with ten equivalent Mg(3)Mg10CrSi cuboctahedra. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1); two Mg(2,2); two equivalent Mg(4); four equivalent Mg(3); one Cr(1); and one Si(1) atom to form distorted MgMg10CrSi cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen equivalent Mg(3)Mg10CrSi cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Cr(1)Mg12 cuboctahedra; edges with two equivalent Si(1)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg10CrSi cuboctahedra; edges with four equivalent Mg(1)Mg10Si2 cuboctahedra;  a faceface with one Cr(1)Mg12 cuboctahedra;  a faceface with one Si(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five Mg(2,2)Mg10Cr2 cuboctahedra; faces with five equivalent Mg(1)Mg10Si2 cuboctahedra; and faces with six equivalent Mg(3)Mg10CrSi cuboctahedra. In the fifth Mg site, Mg(4) is bonded to three equivalent Mg(1); three Mg(2,2); and six equivalent Mg(3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra; corners with twelve equivalent Mg(3)Mg10CrSi cuboctahedra; edges with six Mg(2,2)Mg10Cr2 cuboctahedra; edges with six equivalent Mg(3)Mg10CrSi cuboctahedra; edges with six equivalent Mg(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with three Mg(2,2)Mg10Cr2 cuboctahedra; faces with three equivalent Mg(1)Mg10Si2 cuboctahedra; faces with three equivalent Cr(1)Mg12 cuboctahedra; faces with three equivalent Si(1)Mg12 cuboctahedra; and faces with six equivalent Mg(3)Mg10CrSi cuboctahedra. Cr(1) is bonded to six Mg(2,2) and six equivalent Mg(3) atoms to form CrMg12 cuboctahedra that share corners with six equivalent Cr(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(1)Mg10Si2 cuboctahedra; edges with six Mg(2,2)Mg10Cr2 cuboctahedra; edges with twelve equivalent Mg(3)Mg10CrSi cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Cr2 cuboctahedra; faces with six equivalent Mg(3)Mg10CrSi cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra. Si(1) is bonded to six equivalent Mg(1) and six equivalent Mg(3) atoms to form SiMg12 cuboctahedra that share corners with six equivalent Si(1)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Cr2 cuboctahedra; edges with six equivalent Mg(1)Mg10Si2 cuboctahedra; edges with twelve equivalent Mg(3)Mg10CrSi cuboctahedra; faces with two equivalent Cr(1)Mg12 cuboctahedra; faces with six equivalent Mg(3)Mg10CrSi cuboctahedra; faces with six equivalent Mg(1)Mg10Si2 cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra.
Mg14CrSi crystallizes in the hexagonal P-6m2 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Cr(1)Mg12 cuboctahedra, corners with six equivalent Mg(1)Mg10Si2 cuboctahedra, corners with eight equivalent Mg(2)Mg10Cr2 cuboctahedra, edges with two equivalent Si(1)Mg12 cuboctahedra, edges with four equivalent Mg(1)Mg10Si2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(3)Mg10CrSi cuboctahedra, faces with two equivalent Mg(2)Mg10Cr2 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Si(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Mg10Si2 cuboctahedra, and faces with ten equivalent Mg(3)Mg10CrSi cuboctahedra. Both Mg(1)-Mg(4) bond lengths are 3.14 Å. There are two shorter (3.11 Å) and two longer (3.13 Å) Mg(1)-Mg(1) bond lengths. All Mg(1)-Mg(3) bond lengths are 3.15 Å. Both Mg(1)-Si(1) bond lengths are 3.12 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(4), four equivalent Mg(2), four equivalent Mg(3), and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra, corners with six equivalent Mg(2)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Mg10Si2 cuboctahedra, edges with two equivalent Cr(1)Mg12 cuboctahedra, edges with four equivalent Mg(2)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(4)Mg12 cuboctahedra, edges with eight equivalent Mg(3)Mg10CrSi cuboctahedra, faces with two equivalent Mg(1)Mg10Si2 cuboctahedra, faces with two equivalent Mg(4)Mg12 cuboctahedra, faces with two equivalent Cr(1)Mg12 cuboctahedra, faces with four equivalent Mg(2)Mg10Cr2 cuboctahedra, and faces with ten equivalent Mg(3)Mg10CrSi cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.12 Å. All Mg(2)-Mg(2) bond lengths are 3.12 Å. All Mg(2)-Mg(3) bond lengths are 3.14 Å. Both Mg(2)-Cr(1) bond lengths are 3.12 Å. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(2,2); four equivalent Mg(3); and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Mg10Cr2 cuboctahedra; corners with eight equivalent Mg(1)Mg10Si2 cuboctahedra; edges with two equivalent Cr(1)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight equivalent Mg(3)Mg10CrSi cuboctahedra; faces with two equivalent Mg(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Cr(1)Mg12 cuboctahedra; faces with four Mg(2,2)Mg10Cr2 cuboctahedra; and faces with ten equivalent Mg(3)Mg10CrSi cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.12 Å. Both Mg(2)-Mg(2) bond lengths are 3.12 Å. All Mg(2)-Mg(3) bond lengths are 3.14 Å. Both Mg(2)-Cr(1) bond lengths are 3.12 Å. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1); two Mg(2,2); two equivalent Mg(4); four equivalent Mg(3); one Cr(1); and one Si(1) atom to form distorted MgMg10CrSi cuboctahedra that share corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with fourteen equivalent Mg(3)Mg10CrSi cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Cr(1)Mg12 cuboctahedra; edges with two equivalent Si(1)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg10CrSi cuboctahedra; edges with four equivalent Mg(1)Mg10Si2 cuboctahedra;  a faceface with one Cr(1)Mg12 cuboctahedra;  a faceface with one Si(1)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with five Mg(2,2)Mg10Cr2 cuboctahedra; faces with five equivalent Mg(1)Mg10Si2 cuboctahedra; and faces with six equivalent Mg(3)Mg10CrSi cuboctahedra. Both Mg(3)-Mg(4) bond lengths are 3.12 Å. There are two shorter (3.05 Å) and two longer (3.18 Å) Mg(3)-Mg(3) bond lengths. The Mg(3)-Cr(1) bond length is 3.11 Å. The Mg(3)-Si(1) bond length is 3.12 Å. In the fifth Mg site, Mg(4) is bonded to three equivalent Mg(1); three Mg(2,2); and six equivalent Mg(3) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(4)Mg12 cuboctahedra; corners with twelve equivalent Mg(3)Mg10CrSi cuboctahedra; edges with six Mg(2,2)Mg10Cr2 cuboctahedra; edges with six equivalent Mg(3)Mg10CrSi cuboctahedra; edges with six equivalent Mg(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with three Mg(2,2)Mg10Cr2 cuboctahedra; faces with three equivalent Mg(1)Mg10Si2 cuboctahedra; faces with three equivalent Cr(1)Mg12 cuboctahedra; faces with three equivalent Si(1)Mg12 cuboctahedra; and faces with six equivalent Mg(3)Mg10CrSi cuboctahedra. Cr(1) is bonded to six Mg(2,2) and six equivalent Mg(3) atoms to form CrMg12 cuboctahedra that share corners with six equivalent Cr(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(1)Mg10Si2 cuboctahedra; edges with six Mg(2,2)Mg10Cr2 cuboctahedra; edges with twelve equivalent Mg(3)Mg10CrSi cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Cr2 cuboctahedra; faces with six equivalent Mg(3)Mg10CrSi cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra. Si(1) is bonded to six equivalent Mg(1) and six equivalent Mg(3) atoms to form SiMg12 cuboctahedra that share corners with six equivalent Si(1)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Cr2 cuboctahedra; edges with six equivalent Mg(1)Mg10Si2 cuboctahedra; edges with twelve equivalent Mg(3)Mg10CrSi cuboctahedra; faces with two equivalent Cr(1)Mg12 cuboctahedra; faces with six equivalent Mg(3)Mg10CrSi cuboctahedra; faces with six equivalent Mg(1)Mg10Si2 cuboctahedra; and faces with six equivalent Mg(4)Mg12 cuboctahedra.