Mimetite, whose name derives from the Greek mimethes, meaning "imitator", is an arsenate mineral 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 (5(4)3) and with vanadinite (5(4)3). The most notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.
Industrially, mimetite is a minor ore of lead, especially when found in relatively large quantities. The chief use of mimetite is as a collector's specimen, often creating very attractive botryoidal crusts on the surface of the specimen. Though mimetite is also found in prismatic crystal forms, it is not used as a gemstone due to its softness. The best of these prismatic forms have been found in Johanngeorgenstadt in Saxony and Wheal Unity in Cornwall, England.