Mimetite, Wulfenite Locality: Ojuela Mine, Mapimí, Municipio de Mapimí, Durango, Mexico (Locality at mindat.org) Size: miniature, 5.3 x 5.5 x 2.5 Mimetite with — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Mimetite
Also known as: Campylite.
A lead chloroarsenate — the 'imitator' whose yellow crystal clusters mimic pyromorphite — a secondary mineral of lead deposits.
Intro adapted from Wikipedia (CC BY-SA).
Mimetite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Pb₅(AsO₄)₃Cl.
It crystallizes in the hexagonal crystal system (space group P6_3/m). It is a member of the Apatite structural group.
Key properties: Mohs hardness 3.5–4; specific gravity 7.24; typically yellow or orange or brown or colorless; White streak; Resinous to subadamantine luster; refractive index 2.138; optically uniaxial.
IMA symbol Mim, grandfathered status — known before the IMA’s founding, named in 1832.
A common secondary mineral in the oxidized zone of arsenic-bearing lead deposits.
It is found associated with Cerussite, anglesite, smithsonite, willemite, pyromorphite, wulfenite.
Its name comes from the Greek for an imitator, as it imitates pyromorphite.
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