Pirquitasite, Ag(2)ZnSnS(4).

Pirquitasite, ideally Ag(2)ZnSnS(4) (disilver zinc tin tetra-sulfide), exhibits tetra-gonal symmetry and is a member of the stannite group that has the general formula A(2)BCX(4), with A = Ag, Cu; B = Zn, Cd, Fe, Cu, Hg; C = Sn, Ge, Sb, As; and X = S, Se. In this study, single-crystal X-ray diffraction data are used to determine the structure of pirquitasite from a twinned crystal from the type locality, the Pirquitas deposit, Jujuy Province, Argentina, with anisotropic displacement parameters for all atoms, and a measured composition of (Ag(1.87)Cu(0.