Mimetite


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Related to Mimetite: pyromorphite

mimetite

[′mim·ə‚tīt]
(mineralogy)
Pb5(AsO4)3Cl A yellow to yellowish-brown mineral of the apatite group, commonly containing calcium or phosphate; a minor ore of lead. Also known as mimetene; mimetesite.

Mimetite

 

(from the Greek mimetes, “imitator,” in allusion to mimetite’s resemblance to pyromorphite), also mimetesite, a mineral; a complex lead arsenate of chemical composition Pbs [AsO4]3Cl, often containing P2O5, CaO, and other admixtures. Mimetite crystallizes in the hexagonal system, forming minute prismatic, more rarely acicular, crystals with a high luster. Its crystal structure resembles that of apatite. Usually of pale yellowish green or yellowish brown color, mimetite has a hardness of 3.5 on Mohs’ scale and a density of 7,190–7,250 kg/m3. The mineral gives off a strong garlic odor upon heating, owing to the presence of As.

Mimetite is formed in the oxidized zones of hydrothermal deposits as a result of the oxidation and decomposition of lead ores, as well as in the presence of lennantite, arsenopyrite, or any other arsenides and sulfoarsenides. It is a rare mineral.

References in periodicals archive ?
Plumbian apatite-(CaF) has been found as overgrowths on mimetite prisms (to 1 mm) in a few specimens from the Reward mine.
And, as fairly frequently at the Denver Show, Denver resident Ralph Clark put in a case of selections from his fabulous thumbnail collection--with the Montana veszelyite, Tsumeb mimetite, Chilean proustite, Swiss anatase, etc.
There were also annabergite from Laurium, Greece; kermesite from Pezinok, Slovakia; sphalerite from Banska Stiavnica (Schemnitz), Slovakia; chalcocite and olivenite from Cornwall, England; some top-class vanadinite specimens of recent vintage from Mibladen, Morocco; and a few dozen of the new mimetites from Badenweiler.
Members of the pyromorphite group that occur there include matt-heddleite, mimetite.
Wright's return box was dispatched in June and contained 110 specimens, including many supergene lead and copper minerals (pyromorphite, mimetite, linarite, caledonite, cerussite, etc.
The black gravel made an interesting yet non-intrusive "matrix" for all sorts of fabulous things, from nuggets of fire opal to elaborate jewelry pieces to wonderful specimens of (for example) green mimetite from the Elura mine, crocoite from Tasmania, and dozens of species from Broken Hill.
According to Panczner (1987), mimetite occurs at San Carlos as botryoidal masses associated with vanadinite and calcite; Cook(2001) writes that "fine botryoidal masses of lemon-yellow mimetite from San Carlos .
Specimens from this occurrence remain the finest known examples of botryoidal mimetite in the world.
1291 Mimetite and Carminite, Centennial mine, Eureka, Utah, no.
He then moved on to other projects, the most successful of which were the 1982 discovery of purple adamite at the Ojuela mine in Mexico, and the 1989 find of wulfenite and mimetite at the San Francisco mine in Mexico.
Several areas around the world have produced mimetite but great specimens have been found in only four localities.
Associated species include siderite microcrystals and earthy yellow mimetite patches.