Galena is the crystalline form of lead sulfide, PbS. It is in the cubic system and often forms beautiful silvery cubic crystals that may display twinning or steps. Galena is the major mineral source of lead. It forms beautiful crystals in the cubic system, many of which are prized by collectors.
Galena occurs worldwide and is often found in limestones and dolomites.
Ramsdell, L.S. 1925. The crystal structures of some metallic sulfides. American Mineralogist 10:281-304.