Galena is the primary source of lead and has the formula PbS.
Galena is lead sulfide and is one of the most important ore minerals in economic geology. It commonly forms metallic-gray cubic crystals or massive grains. Its high density and bright metallic luster make it distinctive, while its perfect cubic cleavage allows pieces to break into right-angled fragments.
Galena often occurs in hydrothermal veins with sphalerite, chalcopyrite, pyrite, and silver-bearing minerals. Some galena deposits are important sources of silver as well as lead, because silver can substitute into the galena structure or occur in associated minerals.
Lead has been used historically in batteries, radiation shielding, and other products, but lead compounds are toxic. Sphalerite is the principal zinc ore, chalcopyrite is a copper ore, and cinnabar is the principal mercury ore.