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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

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SUGILITE


SUGILITE (Sugilith—Sugilite——угилит) (Murakami, N. et al., 1976), after Ken-ichi Sugi (1901-1948), a Japanese petrologist discovered the mineral.

Silicate – K[12]Na2[9](Fe3+,Mn3+,Al)2[6]L3[4][Si12O30], subclass rings silicate. Hexagonal system. Hardness 6-6.5. Density 2.7-2.8. Glass luster. Sugilite forms fine-crystalline massive aggregates. Non-transparent to translucent. Color: reddish, purple or yellowish-brown, depending on the manganese in the composition of the mineral. It displays strong pleochroism with changing of color from light bluish-purple – in the daylight, to red-purple – in the artificial light. It is formed in aegirine syenites, and also in the process of contact metasomatism. In Tadzhikistan, it is in boulders from the Dara-i-Pioz massif, Alai Mts. In South Africa, sugilite is produced as an ornamental stone, under the local name wesselite, at the Hotazel mine and the Wessels mine, Northern Cape Prov. It is represented with massive violet-red aggregates there, in the form of interlayer up to 20 cm. thick and small purple-red crystals in manganese ore. Later, they discovered sugilite in India, in the Madhya-Pradesh State; then, in Italy, in the Northern Apennines, at the Cierchiarea mine, East Liguria. Also in Australia, in silicate rock at the Hoskins mine, near Grenfell, and at the Woods Ornamental Rhodonite mine, near Tamworth, New South Wales. In Canada sugilite in crystals up to 2.5 cm. at Mont St-Hilaire, Québec Prov. is known. In Japan, on the Iwagi Is., Ehime Pref., yellowish-brown sugilite is of the mineralogical importance only. Since 1979, sugilite has come into trade under the name lavulite, king’s lavulite or king’s azel. It is cut in cabochon, used in stone-carving and for manufacturing of beads. Translucent segments are faceted. In the Smiths. Inst., Wash., there is a faceted stone 23.5 ct.

Similar gemstones & Imitations. It looks like charoite and sogdianite. At first it was posed as charoite. As material for imitation they use barium phosphate with bonding agents.

 

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