Galena
Galena is the major ore of lead, and has been mined and worked since ancient times, e.g. the Romans used lead for weights, coins, vases, plumbing. Galena, a sulphide mineral, contains up to 86% lead, and may contain up to 1% silver. The large volume of galena that is processed for lead produces enough silver as a by-product to also make galena the leading ore of silver. Galena is a natural semiconductor at room temperature.Galena can be found in hydrothermal veins, as irregular masses in limestones, in zones of contact metamorphism, and disseminated in igneous and sedimentary rocks.
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Chemical composition - PbS
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