Mimetite, whose name derives from the Greek Μιμητής mimethes, meaning "imitator", is a lead arsenate chloride mineral (Pb₅(AsO₄)₃Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name is a reference to mimetite's resemblance to the mineral pyromorphite. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite (Pb₅(PO₄)₃Cl) and with vanadinite (Pb₅(VO₄)₃Cl). Notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.