HfCrCuS4 crystallizes in the monoclinic P2_1/m space group. Hf(1) is bonded to three equivalent S(2) and three equivalent S(4) atoms to form HfS6 octahedra that share corners with six equivalent Cu(1)S6 octahedra, edges with six equivalent Hf(1)S6 octahedra, and  a faceface with one Cu(1)S6 octahedra. The corner-sharing octahedral tilt angles are 47°. Cr(1) is bonded to three equivalent S(1) and three equivalent S(3) atoms to form distorted CrS6 octahedra that share corners with six equivalent Cu(1)S6 octahedra, edges with six equivalent Cr(1)S6 octahedra, and  a faceface with one Cu(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. Cu(1) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form distorted CuS6 octahedra that share corners with six equivalent Hf(1)S6 octahedra, corners with six equivalent Cr(1)S6 octahedra, edges with two equivalent Cu(1)S6 octahedra,  a faceface with one Hf(1)S6 octahedra, and  a faceface with one Cr(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. There are four inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to three equivalent Cr(1) and one Cu(1) atom. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to three equivalent Hf(1) and one Cu(1) atom. In the third S site, S(3) is bonded to three equivalent Cr(1) and two equivalent Cu(1) atoms to form distorted SCr3Cu2 square pyramids that share corners with two equivalent S(4)Hf3Cu2 trigonal bipyramids, edges with four equivalent S(3)Cr3Cu2 square pyramids, and  an edgeedge with one S(4)Hf3Cu2 trigonal bipyramid. In the fourth S site, S(4) is bonded to three equivalent Hf(1) and two equivalent Cu(1) atoms to form distorted SHf3Cu2 trigonal bipyramids that share corners with two equivalent S(3)Cr3Cu2 square pyramids,  an edgeedge with one S(3)Cr3Cu2 square pyramid, and edges with four equivalent S(4)Hf3Cu2 trigonal bipyramids.
HfCrCuS4 crystallizes in the monoclinic P2_1/m space group. Hf(1) is bonded to three equivalent S(2) and three equivalent S(4) atoms to form HfS6 octahedra that share corners with six equivalent Cu(1)S6 octahedra, edges with six equivalent Hf(1)S6 octahedra, and  a faceface with one Cu(1)S6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are two shorter (2.54 Å) and one longer (2.57 Å) Hf(1)-S(2) bond length. There is one shorter (2.54 Å) and two longer (2.57 Å) Hf(1)-S(4) bond lengths. Cr(1) is bonded to three equivalent S(1) and three equivalent S(3) atoms to form distorted CrS6 octahedra that share corners with six equivalent Cu(1)S6 octahedra, edges with six equivalent Cr(1)S6 octahedra, and  a faceface with one Cu(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. There are two shorter (2.37 Å) and one longer (2.42 Å) Cr(1)-S(1) bond length. There is one shorter (2.44 Å) and two longer (2.48 Å) Cr(1)-S(3) bond lengths. Cu(1) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form distorted CuS6 octahedra that share corners with six equivalent Hf(1)S6 octahedra, corners with six equivalent Cr(1)S6 octahedra, edges with two equivalent Cu(1)S6 octahedra,  a faceface with one Hf(1)S6 octahedra, and  a faceface with one Cr(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 47-54°. The Cu(1)-S(1) bond length is 2.45 Å. The Cu(1)-S(2) bond length is 2.49 Å. Both Cu(1)-S(3) bond lengths are 2.45 Å. Both Cu(1)-S(4) bond lengths are 2.64 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to three equivalent Cr(1) and one Cu(1) atom. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to three equivalent Hf(1) and one Cu(1) atom. In the third S site, S(3) is bonded to three equivalent Cr(1) and two equivalent Cu(1) atoms to form distorted SCr3Cu2 square pyramids that share corners with two equivalent S(4)Hf3Cu2 trigonal bipyramids, edges with four equivalent S(3)Cr3Cu2 square pyramids, and  an edgeedge with one S(4)Hf3Cu2 trigonal bipyramid. In the fourth S site, S(4) is bonded to three equivalent Hf(1) and two equivalent Cu(1) atoms to form distorted SHf3Cu2 trigonal bipyramids that share corners with two equivalent S(3)Cr3Cu2 square pyramids,  an edgeedge with one S(3)Cr3Cu2 square pyramid, and edges with four equivalent S(4)Hf3Cu2 trigonal bipyramids.