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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

BENITOITE


BENITOITE (Benitoit—Bénitoïte—Ѕенитоит) (Louderback G.D., 1907), after its discovery location, at the Benitoite Gem mine, San Benito Co., California, the U.S.A. Silicate – BaTi[Si3O9], subclasses ring silicate, hexagonal system. Hardness 6-6.5. Density 3.6. Glass luster. At first, benitoite was taken for sapphire, it also resembles cordierite, kyanite, tanzanite, blue tourmalineindicolite, zircon and blue spinelgahnite. Benitoite, or celestial stone is a rare mineral, discovered first of all in the U.S.A., in California, in veins of natrolite at two deposits of the San Benito Co. – Benitoite Gem and Dallas Gem. It is found in the shape of flattened bipyramidal crystals, 1-1.5 cm. long, more rarely – up to 2.5 cm. long – and up to 5.6 cm. in cross-section. Transparent to translucent. Color: from pale blue to thick blue and violet-blue, colorless one is extremely rare. Zoning and uneven dispersion of color with decreasing of intensity from edges to the center is typical for it; in some segments pink color appears. It displays strong pleochroism from dark blue, purple, greenish-blue to colorless. Special play of light and beauty of faceted stones depends on the high level of dispersion, close to that one of diamond. Findings of benitoite in Texas, the U.S.A., in Belgium, New Zealand, South Korea and Japan are of mineralogical significance only.

Benitoite is highly valued both as a gemstone and as a rare collection stone. After faceting it is usually not more than 2 ct. From 66 faceted pieces of benitoite, mounted in gold and platinum and decorated with brilliants, they made a unique necklace, in which the biggest stone was 6.53 ct. To receive the most beautiful color, in the process of faceting a stone should be placed so that the direction of crystallographic axis was in the plane of the table facet of this stone. The biggest faceted benitoite, 7.83 ct., is kept in the Smiths. Inst., Wash. In the AMNH, N.Y., there is a rare violet-light blue stone in 3.57 ct.

 

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