Some simple copper compounds have unusual crystal structures. Cu[subscript 3]N is cubic with N atoms at centers of octahedra formed by 6 Cu atoms. Cu[subscript 2]O (cuprite) is also cubic; O atoms are in tetrahedra formed by 4 Cu atoms. These tetrahedra are linked by sharing vertices forming two independent networks without linkages between them. CuS (covellite) is hexagonal with two distinct roles for Cu and S. Some layers have linked hexagons formed by 3 S and 3 Cu and there are also layers of Cu atoms and layers of S atoms. The Cu atoms of Cu layers are in tetrahedra formed by one S of a Cu-S layer and three S of an S layer. Each S of an S layer is in a tetrahedron formed by 3 Cu of a Cu layer and an S of another S layer. The two bonded S atoms form S[subscript 2][superscript 2-] ions. Cu[subscript 2]S (high chalcocite) is hexagonal. There are layers of linked CuS[subscript 3] hexagons and there are two Cu layers of tetrahedral sites. Cu atoms in tetrahedral layers are bonded to 3 S of one Cu-S layer and one S of another Cu-S layer. Structures are shown as unit cells and as polyhedra formed by 12 close-packed atoms in three layers to examine the roles of both atoms. Structures and roles of atoms are described by simple notation. (Contains 9 figures and 1 note.)