Chemical Formula: Pb5(AsO4)3Cl
Locality: Treue Freundschaft Mine, Johanngeorgenstadt, Erzgebirge, Saxony, Germany.
Name Origin: From the Greek mimethes – “imitator” , because of its resemblance to pyromorphite.
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.
History
Discovery date : 1832
Optical properties
Optical and misc. Properties : Subtransparent to translucent
Physical Properties
Cleavage: {1011} Imperfect
Color: White, Yellow, Orange, Brown, Red.
Density: 7.1 – 7.24, Average = 7.17
Diaphaneity: Subtransparent to translucent
Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
Hardness: 3.5-4 – Copper Penny-Fluorite
Luminescence: Fluorescent, Short UV=orange, Long UV=orange.
Luster: Adamantine – Resinous
Streak: white
Photos :
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