Lead (Pb) is a relatively common element in Earth crustal materials. Lead is a heavy, soft metal that is a solid at normal atmospheric and crustal pressures. Lead is reactive with oxygen and tarnishes and dulls when in contact with oxygen. Lead is not a good conductor of electricity, heat, sound, or other pressure vibrations.

Lead is found in Earth's crust at an abundance of about 13–20 parts per million. It rarely occurs as a free element, and is found most commonly as a compound in the form of galena (lead sulfide; PbS), anglesite (lead sulfate; PbSO₄), cerussite (lead carbonate; PbCO₃), and mimetite. Geochemically, lead is a moderately active metal that dissolves very slowly in water.

Lead is both ductile and malleable. These properties allow lead to be easily bent, cut, pulled, or otherwise worked to produce specific shapes. The melting point of lead is 621.3°F (327.4°C), its boiling point is about 3,180°F (1,749°C), and its density is 11.34 grams per cubic centimeter.

The largest producers of lead in the world are Australia, China, the United States, Peru, Canada, Mexico, and Sweden. In the United States, more than 90% of all the lead produced comes from a single state, Missouri. Lead is extracted from its ores by first converting the ore to lead oxide and then heating the oxide with charcoal (pure carbon). The lead produced by this process is usually not very pure and can be further refined electrolytically.

Over the past decades, evidence has mounted indicating lead as a significant environmental hazard. Low levels of lead in products (e.g., paint) can accumulate in tissues over time. As a result, many manufactured items (e.g., batteries) now have or seek lead substitutes or provide for contained disposal.

See Also

Chemical Elements; Minerals