Mg6CrFe crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with ten Mg(1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; and faces with eight equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with ten Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(1,1,1); four Mg(3,3); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with six equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Cr(1)Mg10Fe2 cuboctahedra. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with four equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with ten Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with four equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with ten Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(1,1)Mg8Cr2Fe2 cuboctahedra. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3); and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Fe(1)Mg10Cr2 cuboctahedra. In the seventh Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with ten Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra. Cr(1) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(3,3); and two equivalent Fe(1) atoms to form CrMg10Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with six equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Mg(2)Mg10Fe2 cuboctahedra. Fe(1) is bonded to two equivalent Mg(2); four Mg(1,1,1); four Mg(3,3); and two equivalent Cr(1) atoms to form FeMg10Cr2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with six equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra.
Mg6CrFe crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with ten Mg(1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; and faces with eight equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra. There is one shorter (2.92 Å) and one longer (3.14 Å) Mg(1)-Mg(1) bond length. There is one shorter (3.02 Å) and one longer (3.06 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.08 Å. Both Mg(1)-Mg(4) bond lengths are 3.01 Å. Both Mg(1)-Cr(1) bond lengths are 2.97 Å. There is one shorter (2.94 Å) and one longer (3.15 Å) Mg(1)-Fe(1) bond length. In the second Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with ten Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra. There is one shorter (3.02 Å) and one longer (3.06 Å) Mg(1)-Mg(2) bond length. Both Mg(1)-Mg(3) bond lengths are 3.08 Å. Both Mg(1)-Mg(4) bond lengths are 3.01 Å. Both Mg(1)-Cr(1) bond lengths are 2.97 Å. There is one shorter (2.94 Å) and one longer (3.15 Å) Mg(1)-Fe(1) bond length. In the third Mg site, Mg(2) is bonded to two equivalent Mg(4); four Mg(1,1,1); four Mg(3,3); and two equivalent Fe(1) atoms to form distorted MgMg10Fe2 cuboctahedra that share corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with six equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Cr(1)Mg10Fe2 cuboctahedra. Both Mg(2)-Mg(4) bond lengths are 3.01 Å. The Mg(2)-Mg(1) bond length is 3.06 Å. All Mg(2)-Mg(3,3) bond lengths are 3.03 Å. Both Mg(2)-Fe(1) bond lengths are 3.03 Å. In the fourth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with four equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with ten Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra. Both Mg(3)-Mg(1) bond lengths are 3.08 Å. There is one shorter (2.86 Å) and one longer (3.19 Å) Mg(3)-Mg(3) bond length. There is one shorter (3.03 Å) and one longer (3.06 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.90 Å) and one longer (3.18 Å) Mg(3)-Cr(1) bond length. Both Mg(3)-Fe(1) bond lengths are 2.95 Å. In the fifth Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with four equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with ten Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(1,1)Mg8Cr2Fe2 cuboctahedra. Both Mg(3)-Mg(1) bond lengths are 3.08 Å. There is one shorter (3.03 Å) and one longer (3.06 Å) Mg(3)-Mg(4) bond length. There is one shorter (2.90 Å) and one longer (3.18 Å) Mg(3)-Cr(1) bond length. Both Mg(3)-Fe(1) bond lengths are 2.95 Å. In the sixth Mg site, Mg(4) is bonded to two equivalent Mg(2); four Mg(1,1); four Mg(3,3); and two equivalent Cr(1) atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with six equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with four equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Fe(1)Mg10Cr2 cuboctahedra. Both Mg(4)-Cr(1) bond lengths are 3.03 Å. In the seventh Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Cr(1), and two equivalent Fe(1) atoms to form distorted MgMg8Cr2Fe2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with four equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with ten Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with two equivalent Mg(1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; and faces with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra. There is one shorter (2.92 Å) and one longer (3.14 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(4) bond lengths are 3.01 Å. Both Mg(1)-Cr(1) bond lengths are 2.97 Å. There is one shorter (2.94 Å) and one longer (3.15 Å) Mg(1)-Fe(1) bond length. Cr(1) is bonded to two equivalent Mg(4); four Mg(1,1); four Mg(3,3); and two equivalent Fe(1) atoms to form CrMg10Fe2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Cr2 cuboctahedra; corners with six equivalent Cr(1)Mg10Fe2 cuboctahedra; corners with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(4)Mg10Cr2 cuboctahedra; edges with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Fe(1)Mg10Cr2 cuboctahedra; edges with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(4)Mg10Cr2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Mg(2)Mg10Fe2 cuboctahedra. Both Cr(1)-Fe(1) bond lengths are 2.95 Å. Fe(1) is bonded to two equivalent Mg(2); four Mg(1,1,1); four Mg(3,3); and two equivalent Cr(1) atoms to form FeMg10Cr2 cuboctahedra that share corners with four equivalent Mg(2)Mg10Fe2 cuboctahedra; corners with six equivalent Fe(1)Mg10Cr2 cuboctahedra; corners with eight Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with two equivalent Mg(2)Mg10Fe2 cuboctahedra; edges with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; edges with four equivalent Cr(1)Mg10Fe2 cuboctahedra; edges with eight Mg(3,3)Mg8Cr2Fe2 cuboctahedra; faces with two equivalent Mg(2)Mg10Fe2 cuboctahedra; faces with two equivalent Cr(1)Mg10Fe2 cuboctahedra; faces with two equivalent Fe(1)Mg10Cr2 cuboctahedra; faces with four Mg(1,1,1)Mg8Cr2Fe2 cuboctahedra; faces with four Mg(3,3)Mg8Cr2Fe2 cuboctahedra; and faces with six equivalent Mg(4)Mg10Cr2 cuboctahedra.