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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

CROCOITE


CROCOITE (Krokoit—Crocoite— рокоит) (Lomonosov, 1763 in Beudant, F.S., 1832), from Gk. “krokos” – saffron, alluding to its color. Chromate – Pb[CrO4], monoclinic system. Hardness 2.5-3. Density 6.0. Diamond luster. Cleavage in one direction. Fragile. Crocoite is a rare mineral, found, at first, in the Middle Urals, at the Berezovskiy mine; it was named red lead ore, or Siberian red lead. In 1766, it was described by Russ. mineralogist I.G. Lehman (1700-1767), and in 1797 the Fr. chemist L.N. Vauquelin (1763-1829) discovered a new element chromium in it. It is found in the shape of thick-table, often oblong crystals, columnar and grained aggregates. Color: bright yellowish-red, orange to yellow. Transparent to translucent. It displays pleochroism from orange-red to bloody-red. It looks like cinnabar and realgar. In jewelry they use cabochons of massive red leaden ore. Transparent crystals are faceted sometimes for collection purposes. Crocoite is a typical mineral of the zone of oxidation of lead deposits. In Russia, at the Berezovskiy gold deposit, crystals of crocoite reached 10 cm. long. In the same region, at the Mostovskoy placer (form. Monetnaya Dacha) and in the Tochilnaya Mt., near Rezh, they discovered only a bit less in size and quality crystals of crocoite. Crocoite in mixture with cerussite has there the local name beresowite. Another region, where they find gem-quality crocoite, is Australia. It was discovered there, at the Adelaide mine, near Dundas, on the Tasmania Is. in 1886. Crocoite is represented there with transparent crystals up to 30 cm. long, and non-transparent crystals reach even 8 cm. In other countries, findings of crocoite were registered in the U.S.A., in the states of Arizona and California; in Brazil – in Minas Gerais State, at the Goiabeira deposit, near Congonhas do Campo; on the Philippines – at the deposits Camarine Norte and Labo, Luzon Is.; in Romania – at the Rézbánya deposit; in Germany – near Callenberg, Saxony.

Synonyms. Callochrome | Crocosite | Kallochrom, Germ. | Lehmannite, from Russ. mineralogist J.G. Lehman | Chromelead ore | Orange lead ore | Red lead ore | Chrome lead spar | Red lead spar.

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