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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

CHONDRODITE


CHONDRODITE (Chondrodit—Chondrodite—’ондродит) (d’Ohsson, C. 1817), from Gk. “chondros” – a grain, alludes to its frequent granular appearance. Synonym – prolectit, from Gk. “prolegein” – foresees. Silicate – (Mg,Fe,Ti)5[(F,OH,O)2|(SiO4)2], subclass orthosilicates, monoclinic system. Hardness 6.5. Density 3.1-3.2. Glass luster to pitch one. Cleavage in one direction. Fragile. Chondrodite is a rare mineral, which is found in the shape of isometric crystals rich with edges. Transparent to translucent. Color: yellow, orange, reddish or greenish, brownish in the varieties rich with admixtures of iron and titanium. Chondrodite looks like clinohumite and dark almandine. It is formed under contact metamorphism and metasomatism in carbonate rocks. It is a typical mineral of skarn. In Russia, findings of gem-quality chondrodite were registered in the Pribaikalia, in calciphyres of the Ol’khonskoye deposit, in the region of Slyudyanka, as well as in Karelia – near Pitkaranta. In Finland, chondrodite was discovered on the Ole Is., near Turku, and in the same region on the Parainen (form. Pargas) Is. In Sweden, its yellow crystals were found at the Kavlatorp deposit, Kronberg; in Italy – near Monte Somma, in Vesuvius Mt.; in South Africa – at the Palabora mine, Transvaal. In the U.S.A., in the New York State, at the Tilly Foster mine, Patnam Co., together with clinohumite they described well-formed red-brown crystals of chondrodite. From this place they received a faceted gemstone in 3.5 ct. Besides, chondrodite was discovered in New Jersey, at the Sterling Hill deposit. In Canada, gem-quality orange-yellow chondrodite was discovered in the region of Willberforce, Ontario Prov.

Treatment. Transparent parts of crystals available for faceting usually are not more than 3 ct. Dark stones are cut in hollow cabochon. In the Smiths. Inst., Wash., there are two gems of brilliant pattern of faceting – 3 and 6 mm in diameter. J. Kunz mentions a faceted chondrodite 12 mm. in diameter.

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