cerussite

Cerussite is a mineral species with the chemical formula PbCO3, a lead carbonate that forms as the carbonate end-member of the lead minerals. It crystallizes in the orthorhombic system and commonly occurs as a secondary phase in the oxidation zones of lead ore deposits, typically produced by the weathering of galena (PbS) and related minerals. Cerussite can form in crystals and in more massive, stalactitic or botryoidal aggregates.

Its color ranges from colorless to white, gray, or yellowish; transparent to opaque with a distinct adamantine to resinous luster. The mineral has a white streak, hardness of 3 to 3.5 on the Mohs scale, and a relatively high specific gravity of about 6.5. It forms prismatic, tabular, or acicular crystals that are commonly twinned or radiating; crystals are often well-formed when growth conditions are favorable. It is soluble in acids and effervesces when treated with hydrochloric acid.

Occurrence: widely distributed in oxidized lead deposits worldwide; frequently associated with anglesite (PbSO4) and other secondary lead minerals; notable localities include Leadhills in Scotland and Tsumeb in Namibia, among others.

Etymology and history: the name derives from cerussa, Latin for "white lead," referring to the mineral’s pale color and relation to lead pigments. In mineral collecting, cerussite is prized for its clear to translucent crystals and its geometric forms. In production terms, it is not a major ore; lead is primarily obtained from galena, with cerussite being a secondary mineral.

Safety: containing lead, cerussite is toxic if ingested or inhaled as dust; appropriate handling and hygiene are advised when dealing with specimens.