Lead telluride is a chemical compound of lead and tellurium that can be found as the the naturally occuring mineral altaite. It is a narrow gap semiconductor and may be used as an infrared detector material and thermoelectric material. Lead is a heavy metal and stable element with the symbol Pb and the atomic number 82, existing in metallic, organic, and inorganic forms. It is mainly found in nature as the mineral galena (PbS), cerussite (PbCO3) or anglesite (PbSO4), usually in ore with zinc, silver, or copper. (L21, L400)