galena (gəlēˈnə) [key] or lead glance, lustrous, blue-gray mineral crystallizing usually in cubes, sometimes in octahedrons. It is the most important ore and the principal source of lead. It consists of lead sulfide, PbS, but frequently contains silver (it is mined for this metal in some localities) and other accessory metals. It is widely distributed throughout the world, occurring in veins and in bedded deposits, in Missouri, Idaho, Iowa, Wisconsin, and Utah in the United States (leading producer of lead) and in Australia, Canada, England, France, and Mexico. Galena crystals were once much used in radio "crystal" sets.