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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

JET


JET (Gagat—Jais—√агат), after the discovery location on the Gagay Town in Ancient Lydia (now Gages, south-east of Turkey). The Lat. name of gagates had an analogue in Old Fr. – jeiet or jyet, in Old Engl. – geat or gayet, the modern name jet came from those names.

Composition & Properties. Carbon – 60-80%, hydrogen – 6-7.5% and admixtures. Black, solid variety of brown coal, easily processed, well polished; and also a sedimentary rock of bioorganic genesis, classified as a caustobioliths. Amorphous. Viscous. Combustible. Hardness 2.5-4. Density 1.1-1.4. Wax luster, velvet one. Jet is nontransparent. Color: black or dark brownish. Sometimes it contains inclusions of crystals of pyrite and displays wooden texture. Because of its ability to become electric in the process of friction, it is called black amber. Jet is a bad heat conductor, it is warm by touch, and this property is of importance in jewelry. In Great Britain, masters called low-quality jet nettled jet, or French jet.

Deposits. Jet is formed from remains of conifers in sedimentary layers under the anaerobe conditions of the reducing surroundings without preliminary oxidative putrefaction. As a sedimentary rock, it doesn’t form large deposits, opposite to coal; it is found in the form of lenses and nodules in upper and down horizons of coal layers and in other rocks. Average age of it is circa 100 million years. The biggest nodules reach, sometimes, 10 kg. In Russia, deposits of jet are known in the Caucasus – in South Dagestan and near Novorossiysk; as well as on Kamchatka and Sakhalin. Sibeiran jet found at deposits of the Irkutsk, Taymyr and Lena River coal basins is classified as one of the group of sapropelic coals which were described earlier. In the Ukraine, jet was extracted in Crimea, at the Beshuiskoye deposit. In Georgia, deposits of jet are known in the region of K’ut’aisi (form. Kutaisi), and 40 km west from Tbilisi, there is the Metekhskoye deposit of jet. In Great Britain, a tradition region of extraction of jet is the Whitby deposit, on the Yorkshire coast. In the continental Europe, it was extracted in Spain, in the west of Asturias Prov.; in France, its deposits were known in the Ode Dept., but they are worked out now. In Germany, such deposits are situated in Schwab Alba, Baden-Würtemberg; in Poland – in the region of Czènstochov, Silesia. In Asia Minor, the most ancient deposits of jet are known in Lykia, on the territory of modern Turkey. In South-East Asia, it was extracted in Cambodia, on the Fukuok Is., Siamese Gulf, and in the east of the country, by the Laos border; in Japan – on the Kyüshü Is., in the region of Nagasaki. There is information about deposits of jet in China and India. In the U.S.A., its deposits are in the states of Colorado, Maryland, New Mexico and Utah.

Synonyms. Agstein, Germ. | Black amber | Whitby black amber | Arsucarite | Pitch coal | Gisher | Black jasper | ~ jet: Asturiasn ~, bastard ~, Colorado ~, Crimean ~, Utah ~, Whitby ~ | Black rock resin | Scorpion stone | Whitby black turquoise | Yussur, Turk.

Treatment. This ornamental stone although was not one of the most popular but has been well-known among many peoples since the Paleolithic times. At sites of the Stone Age, they found its rounded fragments, processed with flake-instruments. In the southern part of Germany, in the upper reaches of Danube, they discovered the most ancient adornments from jet, dated to the Stone Age. In England and Scotland, in barrows of the Bronze Age, they discovered adornments from jet: beads and necklaces. In the State Museum of Georgia, there are jet beads dated to the 3d millennium B.C. In the Ukraine, in the Khersonnes Museum, Sevastopol, a visitor can see perfectly carved bracelets and signets from jet made about two thousand years ago. In Ancient Egypt, they made toilet sets, combs and looking-glasses from jet. Pliny the Elder in his “Natural History” gave a detailed description of jet. In Ancient Rome, jet came into fashion after the seizure of the British Iss. by Roman troops. They carved bracelets, signets, stamps and gems from it. Pontius Pilate, a procurator of Judaic, wore a signet with a jet inset. Since the 7th cent. A.D., they have made mainly religious objects from jet: small icons, crosses, crucifixes and rosaries. Jet returned to the manufacturing of bijoux in Europe in the 14th cent. English Victorian carvers reached the highest level of perfection in manufacturing of jet adornments. They made necklaces, earrings, beads, cameos, rings, bracelets, brooches, lockets, chains, as well as buttons, paper-knives, candlesticks and different souvenirs from jet. The size of some work of art was significant: the cross-section of jet beads reached 25 mm., and brooches were up to 70 mm. and even more, ear-rings – 106 m. A bust of Mary Stuart from a piece of jet was 60 mm. high, and the length of the jet chain, which was made for a Queen of Bavaria in 1854, was 1500 mm. In the medieval Germany, there were famous masters in jet processing from the city of Gmünd, to the south from Münich. Rosaries from German jet were exported from Germany to other European countries. That time, in France, jet was especially popular; it was used for decoration of mirrors, chandeliers and furniture. In Spain, the center of jet trade was the city of Santiago de Compostella, Prov. de La Coruña, where Spanish jet was called asobache. Obviously there a wonderful sculpture was cut from jet – “Mourns of Our Lady”, which kept in the Museum of Gmünd, Germany, now. In the 17th cent., amulets from Würtembergen jet in the shape of fig came into fashion; they wore them as a mean of protection against an “evil eye.” By the middle of the 19th cent., in Spain, desolated jet trade was resurrected. Masters used more perfect instruments and created unique sculptures up to 180 mm high and even sculpture groups, where jet was combined with ivory.

In the U.S.A., carving in jet was popular among local Indians. A typical feature of their products is the combination of jet with turquoise. Nowadays, modern technologies and cheap materials like obsidian and plastics almost completely replaced jet. It can be found mainly in funeral jewelries. However, in Spain and England, still there are artistic trades of manufacturing of jet souvenirs. In Russia, masters working in jet are in the Irkutsk Region only. Some works of art from Crimea made in jet were exhibited at the World Show in Montreal in 1968. At gemstones shows, there are sometimes jet produce by Georgian carvers.

Legends. In ancient times, jet was supposed to be a symbol of sorrow. As a talisman, it softens parting and soul ache. An amulet from jet used as a mean of protection against evil spirits and ghosts, as well as snake bites and diseases. In the Middle Ages, they considered that it strengthened vision and protected against black eye. In black magic it was used for calling of dead souls. Astrologers take jet for a stone of Saturn; it is good for those who were born under the sign of Capricorn, and also for Pisces and Cancer.

Similarity & Imitations. Jet looks like morione, black garnet – melanite, black tourmalineschorl or mountain jet, black obsidian, black onyx – chalcedony, fossil coals, hard bitumen, black glass. They are usually used as imitations of jet, as well as black onyx, plastic – bakelite, lack vulcanized rubber – ebonite or vulcanite, fumed oak, horn. In the 19th cent., gall imitations appeared: black glass – Paris jet, or French jet and Vox-Hall glass. In Great Britain, a typical imitation jet is bituminous brownish-black Kimeridgian slate. In Spain, they use artificial material for this purpose – obviously cemented with epoxy resin from jet dust – compacto asobache.

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