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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

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MIMETITE


MIMETITE (Mimetesit—Mimétite—ћиметизит) (Beudant, F.S. 1832), from Gk. “mimetis” – an imitator, after its resemblance to pyromorphite. Arsenate – Pb5[Cl|(AsO4)3], hexagonal system. Hardness 3.5-4.5. Density 7.1. Greasy luster to diamond one. Fragile. Mimetite forms a row of constant miscibility with pyromorphite and vanadinite. Usually it is represented with oblong columnar and keg-shaped crystals, as well as grained kidney-shaped aggregates, resembling stalactites. Translucent to transparent. Color: yellow, yellow-orange to yellow-brown. Phosphorus-containing jewelry-ornamental variety of mimetite – campylite displays the similar properties. It is represented with kidney-shaped aggregates of bright orange color.

Deposits. Mimetite is found in the oxidation zone of lead deposits. In Russia, it was described in the South Urals, in the of Balta-Tau area. In East Transbaikalia, it was found at the Trekhsvyatitel’skiy mine, near Gornyi Zerentui; and also at the mines Klichka and Kadainskiy. In Kazakhstan, mimetite was discovered at the Gul’shad deposit and at the Kyzyl Espe mine, Balkhash region. In Uzbekistan, it was discovered at the Sargardon deposit, Chatkalskiy Ridge. In Europe, its ornamental variety campylite is found in the Great Britain, at the Dry Gill mine, near Coldbeck Fells, Cumbria; and in Scotland – at the deposits Leadhills and Wonlokhid. In Germany, superb barrel-shaped crystals mimetite up to 2 cm. at Johanngeorgenstadt were discovered, Erzgebirge, Saxony; and also near Zellerfeld, Harz Mts., Lower Saxony. The best gem-quality mimetite is extracted in Namibia, at the Tsumeb deposit, where they found it transparent orange-yellow crystals up to 6 cm. long. They made faceted stones up to 7 ct. from them. In Morocco, findings of mimetite crystals are known at the Taouz deposit. In China, splendid groups of orange crystals up to 2 cm. occurs at the Pingtouning mine, Guangdong Prov. In Australia, it was extracted at the Mt. Bonnie mine, Northern Territories; and at the Broken Hill deposit, New South Wales. In Thailand, at the Hat-Yai deposit, they found crystals of mimetite up to 2 cm. In Mexico, ornamental mimetite of good quality was extracted at the deposits San Pedro Corralitos and El Potosí, Chihuahua; and also Ojo Caliente, Zacatecas.

Cut Gems. Because of their bright color and strong luster, transparent crystals and grained aggregates of mimetite are of interest for jewelers.

Synonyms. Lead rhombohedral baryte | Campylite, from Gk. “kampylos” – turned, after the shape of its crystals | Lead flowers | Gorlandite, after the Gorland deposit, Great Britain | Kampylit, Germ. | Arsenical lead ore | Ragged ore | Phosphormimetite, a variety enriched with phosphorus | Prixite, after the discovery location near Prix, France | Arsenical lead spar.

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