Cu3AsSe4 is Lavarevi\'{c}ite-like structured and crystallizes in the tetragonal I-42m space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent As(1)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent As(1)Se4 tetrahedra and corners with eight equivalent Cu(1)Se4 tetrahedra. As(1) is bonded to four equivalent Se(1) atoms to form AsSe4 tetrahedra that share corners with four equivalent Cu(2)Se4 tetrahedra and corners with eight equivalent Cu(1)Se4 tetrahedra. Se(1) is bonded to one Cu(2), two equivalent Cu(1), and one As(1) atom to form corner-sharing SeCu3As tetrahedra.
Cu3AsSe4 is Lavarevi\'{c}ite-like structured and crystallizes in the tetragonal I-42m space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Cu(1)Se4 tetrahedra, corners with four equivalent Cu(2)Se4 tetrahedra, and corners with four equivalent As(1)Se4 tetrahedra. All Cu(1)-Se(1) bond lengths are 2.38 Å. In the second Cu site, Cu(2) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent As(1)Se4 tetrahedra and corners with eight equivalent Cu(1)Se4 tetrahedra. All Cu(2)-Se(1) bond lengths are 2.40 Å. As(1) is bonded to four equivalent Se(1) atoms to form AsSe4 tetrahedra that share corners with four equivalent Cu(2)Se4 tetrahedra and corners with eight equivalent Cu(1)Se4 tetrahedra. All As(1)-Se(1) bond lengths are 2.45 Å. Se(1) is bonded to one Cu(2), two equivalent Cu(1), and one As(1) atom to form corner-sharing SeCu3As tetrahedra.