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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

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PYROMORPHITE


PYROMORPHITE (Pyromorphit—Pyromorphite—ѕироморфит) (Wallerius, 1748 in Hausmann, J.F.L. 1813), from Gk. “pyr” – fire, plus “morphe” – form, alluding to the crystalline shape assumed by melted globules of the mineral on cooling. Phosphate – Pb5[Cl|(PO4)3], hexagonal system. Hardness 3.5-4. Density 6.7-7.0. Tar luster to diamond one. Fragile. For pyromorphite columnar and barrel-like crystals are typical, not rarely – with cylindrical cavity along the long axis. It is found in the form of crusts and grained aggregates. It forms pseudomorphs on galena. Transparent to translucent. Color: mainly green of different tones, and also brown, yellow, orange-yellow, rose, colorless. Pyromorphite is found in the zone of oxidation of hydrothermal sulfide deposits.

In Russia, it was discovered in the Middle Urals – at the Berezovskiy mine; in Eastern Transbaikalia – at the Zerentuevskiy mine. In Central Kazakhstan, crystals of pyromorphite were found at the Ken Choku deposit, in the region of Qarqaraly (form. Karkaralinsk). In other countries, gem-quality crystals were found in Bulgaria – at a deposit in the region of Momchilgrad. In Czech Rep., pyromorphite in crystals up to 3 cm. was represented in ores of the deposits Príbram and Stríbro, Bohemia (historical region). In Germany, in Rhineland-Palatinate, green or brown crystals were described at the Friedrichssegen mine, near Bad Ems; and Rosenberg mine, Braubach. In France, in the Corrèzé Dept., pyromorphite is known at the Les Farges mine; also in Brittany there are chlorine and yellow-brown crystals up to 5 cm. In Spain, it was discovered in crystals up to 3 cm. at the El Horcajo mine, Ciudad Real Prov. In the U.S.A., in Idaho collection crusts of pyromorphite and green, yellow and brown crystals available for faceting up to 6 cm, were extracted at the Bunker Hill deposit, Shoshone Co. In Mexico, in the Chihuahua State, pyromorphite was discovered at the deposits Guazapares and San José; its beautiful crystals in the Durango State at the Ojuela deposit, near Mapimí, were found. In Australia, it was found in Queensland, on the pegmatite field Gala Creek, the region of Mout Isa, – crystals up to 3 cm.; and in New South Wales, at the Broken Hill mine.

Synonyms. Lead apatite | Cherokine, after the discovery location near Cheroki, in Georgia, the U.S.A. | Green lead crystal | Phosphoric lead | ~ ore: green ~, brown lead ~, green lead ~, motley lead ~. | Polychrome, from Gk. “polychromos”, after the color | Polysphaerite, from Gk. “poly” – many and “sphere” – a sphere, a ball, after the shape of its aggregates | Green lead spar | Phosphoric lead spar | Rhombic lead spar.

Treatment. Transparent crystals of pyromorphite and crusts of its small crystals are of interest for collectors. At the jewelry and gemstone show in Tucson (1997), the U.S.A., the best pyromorphite crusts from the Bunker Hill deposit were evaluated up to $20,000 for a piece.

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