Mimetite is a lead arsenate chloride mineral (Pb₅(AsO₄)₃Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cryst ...

and arsenopyrite. The name derives from the Greek Μιμητής ''mimetes'', meaning "imitator" and refers to mimetite's resemblance to the mineral pyromorphite. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite () and with vanadinite (). Notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.

Properties

Mimetite is a lead chloride arsenate mineral with the composition . It is a secondary mineral, formed by oxidation of primary lead minerals in arsenic-bearing lead deposits. It typically forms short hexagonal crystals that are yellow to brown to orange in color, very brittle, moderately hard ( Mohs hardness 3.5-4), and dense ( specific gravity 7.24). It is distinctive for its lack of transparency, its resinous to adamantine luster, and its solubility in nitric acid. Mimetite forms a complete solid solution series with pyromorphite, with phosphate () substituting for arsenate (). The two minerals are almost identical in their properties and can be difficult to distinguish except by laboratory tests. Pyromorphite is the more common mineral at most locales. Campylite is a name applied to mimetite or pyromorphite that crystallizes as distinctive barrel-shaped crystals forming curved hemispherical aggregates. Bellite is a name formerly applied to a chromium-bearing mimetite, or possibly a mixture of crocoite, mimetite and quartz, which forms attractive orange red crystals, but has been discredited as a distinct mineral species.

Occurrences

Mimetite is found in association with lead and arsenic minerals, including pyromorphite, cerussite, hemimorphite, smithsonite, vanadinite, anglesite, pyrite, mottramite, willemite, and wulfenite. Good specimens have been reported from Gila County, Arizona, US;

Ojocaliente Ojocaliente (population ~44,144) is a medium-sized town in the southeastern part of the Mexican state of Zacatecas. It is considered the center of México. The town was founded in 1620; its first name was "Real Villa de Sacramento y Ojocaliente ...

, Zacatecas, Mexico;

Cumberland Cumberland ( ) is a historic county in the far North West England. It covers part of the Lake District as well as the north Pennines and Solway Firth coast. Cumberland had an administrative function from the 12th century until 1974. From 19 ...

, England; Johanngeorgenstadt, Saxony, Germany; Namibia; and

Broken Hill Broken Hill is an inland mining city in the far west of outback New South Wales, Australia. It is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Highway (B79), in the Barrier Range. It is ...

, Australia.

Mimetite specimen gallery

File:Mimetite-119809.jpg, Botryoidal mimetite in a vug in limonite matrix File:Mimetite-cktsu-48a.jpg, Cluster of translucent, golden mimetite crystals File:Mimetite-289052.jpg, Spherical aggregates of botryoidal mimetite File:Mimetite-176701.jpg, Mimetite, Pingtouling Mine,

Guangdong Province Guangdong (, ), alternatively romanized as Canton or Kwangtung, is a coastal province in South China on the north shore of the South China Sea. The capital of the province is Guangzhou. With a population of 126.01 million (as of 2020) ...

, China. Size: 2.2 x 2.1 x 1.8 cm

References

External links

*{{cite EB1911, wstitle=Mimetite , volume=18 , short=x
Mineral Galleries
Lead minerals Halide minerals Arsenate minerals Hexagonal minerals Minerals in space group 176 Luminescent minerals