s
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

JADEITE


JADEITE group (Jadeit—Jadéite—∆адеит) (Damour, A. 1863) from Span. “piedra de yjada” (pietra de Hijada) – “stone of the flank” or “stone of the loins”, with reference to its supposed efficacy in treating kidney disease. From here went Fr. le jade, and Engl. jade. The name jade joined jadeite and nephrite till 1863, when the Fr. scientist A. Damour shown their difference. However, till nowadays, both gemstones are described together as jade.

Composition & Properties. Silicate – NaAl[Si2O6], subclass chain silicate, group pyroxenes, monoclinic system. Hardness 6.5-7. Density 3.2-3.4. Glass luster. Cleavage in two directions. Viscous in aggregates. It forms rows of constant miscibility with other pyroxenes: diopside, omphacite and aegirine. Because of its high popularity as gemstone, jadeite takes a separate from pyroxenes description. Together with jadeite such close to it stones are described: kosmochlor – NaCr[Si2O6] and omphacite – (Ca,Na)(Mg,Al)[Si2O6], which forms an isomorphic row with omphacite. All of them are ornamental stones, excluding half-transparent emerald-green variety of jadeite, which is ascribed to the most expensive gemstones and it is composed mainly with chlormelanite. Jewelry-ornamental jadeite can be polychromatic and it is characterized with the diversity of structures. It is composed with all the varieties of pyroxenes of the jadeite row and it is a rock, which might be more correctly named jadeitite. Ornamental jadeitite is a non-transparent, different-grained rock of the homogeneous texture. Gray rock is composed with jadeite, dark green one – with omphacite. Other massive viscous green rocks resembling jadeite are used for its imitations. In Western gemology, these rocks are used to be called with the general name jade. (See their list in App. 16).

Jadeite usually forms veined bodies and lenses in other rocks. Non-transparent to half-transparent. Color: white, gray, orange, yellowish-brown, brownish, green of different tones, red, pink-violet and black. Green tones of jadeite depend on the admixtures of iron (Fe3+) and chromium, blue ones – iron (Fe2+ and Fe3+) – blue jade, yellow and brown to red – with the domination of iron (Fe3+). The most enriched with chromium is bright green chrome-jadeite. Besides, the color of jadeite can depend on the admixtures of manganese and nickel. Numerous names of jadeite are in the App. 16. As inclusions in ornamental jadeitite, magnetite can be observed; it produces black color in jadeitite. Jadeitite with admixtures of albite, tremolite and bedding rock is called jade matrix, and jadeite with inclusions of crocidolite – percivalite. Emerald-green chrome analogue of jadeite kosmochlor, usually later in the time of its forming, than jadeite, can be represented with breccia-spherical aggregates. Another mineral of the group of jadeite is omphacite, which forms rows of constant miscibility with diopside, jadeite and aegirine. It is represented with half-transparent, columnar crystals up to 5 cm. long, radial-rayed and grained aggregates. Color: green of different tones, blue-green, blue, colorless and porcelain-white.

Deposits. Omphacite and jadeite are formed in the contact metasomatism, under high pressure in kimberlites, eclogites and glaucophane-schists. At deposits of this type the main mass is represented with gray jadeite, and gem-quality varieties with dull green omphacite and kosmochlor, emerald-green chlormelanite and white, translucent jadeite, which is called pantha in India. In Russia, exploiting of jadeite deposits is holding in hyperbasite massifs of the Polar Urals – the Pus’yorka deposit, in the massif Syum Keu, in the massif Ray Iz – the Karovoye deposit; and in the massif Voikaro-Syniinskii – the Levyy Kachpel’ deposit. At all these deposits, resources of jewelry-ornamental jadeitite are calculated. These deposits are situated in the north end of the Ural ophiolite zone. In the South Urals, in the Ural Tau Ridge, in the Maksyutovskiy complex, they discovered ornamental chlormelanite, close in content to aegirine-jadeite. In the West Sayan Mts., in the Borusskiy hyperbasite massif there is the Borus deposit in the basin of the Kantegir River, a right tributary of the Yenisey River. In 1976-1986, at this deposit geological researches were held, and industrial resources of jewelry-ornamental jadeite were calculated. In Yakutia, chlormelanite was discovered in xenolites of kimberlitic pipes. In the north of Kamchatka, in the Kuyul’skiy hyperbasite massif, on the Koryakskoye Plateau, deposits of jadeite with chlormelanite and omphacite were discovered in 1981. In 1984-1993, in the Tkhachskiy ultramaphic massif, a large vein of greenish-gray jadeitite was opened. That jadeitite contains inclusions of sphaerolites of diopside-jadeite and can be classified as an ornamental stone.

In 1932, in Kazakhstan, in the Kounrad Dist. of the Karaganda Region, they found jadeite rocks; and in 1966-1986, Itmurundy the largest deposit of jadeite was researched there. It contains industrial resources of jewelry-ornamental rough material. Separate blocks of jadeite reached their 1.5 ton. In Kyrgyzstan, there a Bashkeltubek deposit of jadeite. In Armenia, at Sevan Lake, such ornamental stone as Sevan jade, or sevanite was discovered. This rock, resembling rodingite, is represented with boulders covered with crust of chlormelanite and it is composed with amphiboles, vesuvianite with admixture of calcite, chlorite, serpentine and magnetite. Among the other countries, we should mention France, where aegirine-jadeite was discovered on the Corsica Is. In Italy, it was found as an ornamental stone at the Italian Alps, near Val di Susa, Piedmont. Findings of jadeite were registered in Scotland, Great Britain, and Ireland. In Turkey, they found violet jadeite. In South Africa, they extract chlormelanite as an additional material from kimberlites. In New Zealand, jadeite is not of really good ornamental quality. It is also found on Samoa Iss. in the Pacific Ocean.

In Indochina, the most famous is Myanmar (Burma), which possesses the largest deposits of jadeite; they are situated in the north-west of the country, in the Kachin State, near Myitkyina. From the13th cent., they exploited placers in the upper reaches of the Uyu River, a left tributary of the Chindwin River. In 1871, they discovered basic deposits of jadeite in serpentinites. They are situated in the Kachin Mts., and in the basin of the rivers Chindwin, Tau Mau, Mien Mau, Khveka, Pakhan, Pang Mau, Mamon and others. In the region of Tawmaw Khapakan, near Mogaung, only at the Kamaing deposit they extract half-transparent imperial jadeite. At the Namshaimau deposit, they find an ornamental rock, which has the local name maw-sit-sit jade. It is composed with kosmochlor, albite and natrolite, it is light green with dark green spots and veins of jadeite. Earlier, natrolite in it was taken for albite – albite jadeite. In the east of China, they discovered deposits of jadeite in the Henan Prov. – in the Nanyang locality; and in the Liaoning Prov. they found the biggest block of jadeite, more than 160 tons, volume about 80 m3. Besides, findings of jadeite are known in the Hebei and Yunnan Prov. and in Tibet. In Indonesia, a deposit of jadeite is known on the Sulawesi Is. In Japan, jadeite is extracted on the Honshu Is., and in the Ohmi Kotaki region, Niigata Pref., there is a deposit of diopside-jadeite. Recently, in India, they discovered a region with jadeite in the Jammu and Kashmir State (disputed area).

In the U.S.A., they exploit several deposits of ornamental jadeite at the spurs of the Border Range in California – Clear Creek, San Benito Co.; Leech Lake, Mendocino Co; and near Pasa Robles, San Luis Obispo Co. At the Clear Creek deposit, they find veins of white jadeite. At the Leech Lake deposit, jadeite is found together with nephrite and rodingite. Besides, small deposits of jadeite are in the states of Wyoming and Nevada. In Canada, jadeite was discovered in the Yukon Prov. In Costa Rica, they found it on the St Helena Penin. In Guatemala, at placers along the Metagua River, El Progresso Dept., they extracted gray-green, yellow-green diopside-jadeite – mayaite with insets of pyrite, which had the local name quetzalztli. The most commercial importance a dark green to black variety has there – chlormelanite as well as very rare blue jadeite. In Colombia, deposits of jadeite and nephrite are in the region of Bogotá, Magdalena Dept. Findings of jadeite are known also in Mexico, in the Tuxla region.

Unique finds. Two large boulders of jadeite are exhibited in the Geol. Museum, London; the biggest one is 80 kg. In China, in the “Imperial Palace” in Beijing there is a boulder of jadeite more than 2 ton.

Synonyms. Chrome-acmite | Chalchihuitl, Mexican | Chlormelanite, from Gk. “chloros” – green and “melas” – black, after its color | Jadeite-chlormelanite | Chromomphacite | Blue diopside | Diopside-jadeite | Kosmochlor (cosmochlore), from Gk. “kosmos” – cosmic space and “chloros”, after the first finding in meteorite and green color | Mayaite, it was found in tombs of Maya, Central America | Omphacite, from Gk. “omphax” – unripe grapes, after its color | Aegirine-omphacite- | Diopside-omphacite | Tuxtlite, after the discovery location near Tuxla, Mexico | Ureite, after the American researcher G.K. Urey.

Jade (See appendix 16) – Chiung’ui, Chinese, syn. red jade | Common jade | Hsi jade, Chinese, colorless or black | Burmese jadeite, or alkali jadeite, opposite to diopside-jadeite | Green jasper | Kimpi, red jadeite | Percivalite, after surname Amer. geologist J.G. Percival | Plasma smaragd |~ stone: imperial ~, kidney ~, lumbar ~, mountain ~, yu ~, water ~. | Tawmawite – chrome-jadeite, after the discovery location near Tau Mau, Myanmar | Lat yay |Mya yay – emerald-green, Myanmar | Feits’yu, Chinese “kingfisher plumes”, syn. kingfisher jade, after the color of plumes of this bird | Fei-ts’ui yü, or kingfisher-green jade (Shipley R.M., 1974).

Quality improvement. Under weathering, the surface of jadeite becomes reddish-brown, because of a fine film like patina. Thermoprocessing of jadeite can copy such transformation of color. Under such improvement of pale colored stone they receive lavender jade from green Burmese jadeite. Annealing of pale colored jadeite in the restoration atmosphere strengthens its hue. Sometimes, jadeite is improved with coloring of its surface with the solution of ammonium dichromate under the temperature of 130°C and pressure up to 200 atm. with further thermoprocessing under the temperature 400°C in mineral oil. It strengthens green color, but the new tone is not stable. They practice also coating of produce from jadeite with special resins, which makes them more transparent and strengthens their luster.

Treatment. Tools and, perhaps, the first adornments from jadeite appeared 2500-2000 B.C. On the territory of Kazakhstan, jadeite was extracted in 2000-1700 B.C. Jadeite was a ritual stone for ancient civilizations of Central America and was evaluated higher than gold. Because its soundness, it can be carved exquisitely. In the 3-1ss cent. B.C., Olmecs carved figures of gods and amulets from it. Maya made mosaic masks, and Toltecs – figures of jaguar and feathered snakes. In the 14th cent. The remarkable jadeite adze, generally known as the “Kunz Adze” was found in Oaxaca, Mexico. It is grotesque human figure of a light greenish-gray hue, with a slight tinge of blue, this is 272 mm. long, 153 mm. wide and 118 mm. thick; its weight is 7,132 gm. This jadeite artifact brought to U.S.A. about 1890, and is now in AMNH, N.Y. A role of jadeite was especially big in the history of Eastern stone-carving art. In Ancient China, they kept it as a sacred stone and used at first only for state stamps and symbols of Imperial authority. Many museums are proud of their collections of Chinese carved work of art. In one of Berlin museums, there is a flute from jadeite made in India in the 16-17ss cent. In the British Museum, London, there is a turtle from jadeite, 50 cm. in size. The biggest sculpture from gray-white jadeite, cut from a whole block of stone, is in the “Temple of Jade Buddha” in Shanghai, China; it is 1.9 m. high and 1.35 m. wide. This block was found in Myanmar (Burma) more than 100 years ago. In the “Great Palace” in Bangkok, there is a similar sculpture of “Emerald Buddha”, 66 cm. high and 48.3 cm. wide in its base, made from a whole block of green jasper. Among the contemporary pieces of art, we should mention a carved jadeite pagoda in the Oakland Museum, New Zealand. It was faceted from a block of apple-green jadeite, about 8 ton in mass. During 10 years, 150 masters were working on it.

At the world market, there are three grades of jewelry-ornamental jadeite. The first one is “imperial”, translucent to almost transparent, even emerald-green in color. It is found as veins and isolations up to 5 cm. The second grade is “commercial”, green, and non-transparent with veins of higher quality. The third, ornamental grade is “utility”, green, and non-transparent. Evaluating jadeite thy thoroughly analyze both tones of it color and specifics of its texture. Jadeite is a traditional material in stone-carving and in jewelry. The biggest processed gem-quality jadeite of emerald-green hue was a stone of 750 ct. In 1980, it was evaluated in more than $2 million. at the exhibition in Rangoon, Myanmar (Burma).

Legends. Astrologers keep jadeite as a stone of the Earth and the zodiac sign of Virgo. It is a lucky stone for those, who were born under the sign of Libra. As a talisman, it strengthens the virtues of its owner. They suppose it can regulate blood pressure. In the U.S.A., jadeite is an official emblem of Alaska.

Synthesis. Synthetic jadeite is made with the method of caking of orthoclase, kaolinite, nepheline syenite, and also powders of oxide of lead and zinc. Another method is growing of monocrystals from a solution in melting, including coating of base with colored layers. They use also the method of hydrothermal synthesis. In the U.S.A., green and pale lilac jadeite are produced as an experiment by the firm “General Electrics” with the method of caking of powders with 1984.

Similar Gemstones & imitations. Jadeite looks like nephrite, it is resembling many jades in its massive varieties (See App. 17). During several thousands of years till 1863, jadeite and nephrite were not distinguished, both were called jade. Because of the popularity of this gemstone, they used different minerals and rocks for its imitations. On the New Guinea Is., they use astridite for such purpose, which was called after the Belgian Queen Astrid. It is a green rock of ultra basic content, which consists of fibrous dark green jadeite replacing olivine; veins of opal and inclusions of chrome spinel – picotite. As an ornamental stone, it is well polished. Carved products from this stone are used by aboriginal population in ritual purposes.

Search