Formula
(repeating unit) Pb5(AsO4)3Cl Crystal system Hexagonal | Strunz classification 8.BN.05 Space group P63/m | |
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Category Arsenate minerals
Apatite group Crystal class Dipyramidal (6/m)
(same H-M symbol) | ||
Mimetite, whose name derives from the Greek Μιμητής mimetes, 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.
Contents
Uses of mimetite
Industrially, mimetite is a minor ore of lead. The chief use of mimetite is as a collector's specimen, often creating 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. Quality prismatic forms have been found in Johanngeorgenstadt in Saxony and Wheal Unity at Gwennap in Cornwall, England.
Associated minerals
Mimetite is found in association with lead and arsenic minerals, including those minerals with which it forms a series. Some associated minerals include: calcite, galena, pyromorphite, smithsonite, vanadinite, and wulfenite.
Alternative names
Alternative names of mimetite include arsenopyromorphite, mimetesite, and prixite. Campylite is the name for a variety with barrel shaped crystals of a brownish-red or orange-yellow color and containing a considerable proportion of phosphoric acid.