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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

SPODUMENE


SPODUMENE (Spodumen—Spoduméne——подумен) (d’Andrada J.B., 1800), from Gk. “spodumenos”, reduced to ashes, because of the grayish white mass that is formed when the mineral is ignited.

Composition & Properties. Silicate – LiAl[Si2O6], subclass chain, a group of pyroxenes, monoclinic system. Hardness 6.5-7. Density 3.0-3.2. Cleavage perfect in two directions. Fragile. Glass luster, in joints – pearls one. It is found as columnar, often flattened crystals of the board shape. The maximum length can be up to 16 m. Translucent to transparent, absolutely transparent crystals are very rare. There are such varieties of color. Kunzite – pink to light bluish-violet, called after the American mineralogist J.F. Kunz (1856-1932), who described this mineral in California, the U.S.A. Its color depends on admixture of manganese (Mn3+). Pink color is not stable, it is weakened in time, and especially it is obvious in spodumene from Brazil. Nuristanite – light blue to dark blue spodumene, called after the Nuristan region, North Afghanistan. Hiddenite – yellowish-green and emerald-green, called after the American researcher W.V. Hidden (1853-1918), who found this mineral in North Carolina. Its color depends on admixture of vanadium (V3+), chromium (Cr3+) or iron. However, some gemologists believe that the name hiddenite should be used for chromium-containing emerald-green spodumene from deposits of North Carolina, the U.S.A. only. Yellow and green varieties don’t loose their color. Crystals of hiddenite are less in size than crystals of kunzite. Triphane – colorless, pale to dark yellow, gray. Its name is from Gk. “triphanes” – seen in thrice, because of its three-direction cleavage. In mineralogy the Commission of IMAdiscredits this obs. name. Its color depends on admixture of iron. For spodumene it is typical to display pleochroism. Color of kunzite changes from purple-violet to colorless, color of hiddenite – from emerald-green to light bluish-green and to colorless. In processed spodumene sometimes there is the weak effect of cat’s-eyespodumene cat’s-eye, which is produced with tube channels, oriented in parallel to the main crystal axis.

Deposits. Spodumene is usually found in granite pegmatites. In Russia pegmatites with spodumene in the Kolmozero area on the Kola Penin. are known. They are also found in the southeastern part of the Rep. of Tyva, at the deposits Tastyg and Kara-Adyr, Sangilen Ridge. Spodumene is represented there as crystals up to 5 m. long, they have transparent parts of greenish hiddenite. Besides, it is found in the Yenisey Ridge, in pegmatites on the Enashimo River, 70 km to the south from the Severo-Yeniseysk; in East Sayan Mts. – at the Bel’skoye deposit; and also in East Transbaikalia – at the Zavitinskoye deposit. In the Ukraine, spodumene at the Zheltorechenskoye deposit, Krivoy Rog region, was found. In Kazakhstan pegmatites with spodumene at the Ungursai mine, Ust’ Kamenogorsk region, were extracted. In the southern part of Kyrgyzstan they are found in the Turkestan Ridge, along the Kara-Su River. In North Tadzhikistan, at the deposit Samzhon, spodumene crystals reached 1 m. They were found also near the glacier Tro, in the upper reaches of the Zeravshan River. In Europe, gem-quality spodumene is known in the western part of Finland, at the deposit Haapaluoma, to the south from Seiniaioki. In the north of Sweden, it was found at the deposit Varuträsk, to the west from Skellefteo; in Norway – in the region of Langesund, Telemark. In Austria, spodumene is known at the deposit Weinebene Pass, Carinthia; and in Lachtal Valley, Styria. Also in Spain, in pegmatites with beryl, in crystals up to 30 cm. at Lalin locality, Pontevedra Prov. On Greenland, at the deposit Narssârssuk and others they found large crystals of yellow and green spodumene.

In Africa, spodumene deposits are discovered in Mozambique, in pegmatites of the Alto Ligonha region, where they find its crystals up to 2 m. long. In Congo (Kinshasa), there is the deposit of spodumene Manono, in the Katanga Prov. In Malawi they found big crystals of kunzite in pegmatites. On Madagascar, in pegmatites they find kunzite as well as hiddenite, together with other gemstones. In the central part of the island spodumene is extracted at the Maharitra deposits, Vanakarata and Anjanabonoina, 65 km. to the south from Antsirabe, and near Sakaraha, in the south-western part. In Western Australia, in the region of Greenbushes there is the pegmatite field Balingup, where they extracted spodumene. In Afghanistan, of pegmatite deposits found in the 20th cent., because it became one of the most important suppliers of spodumene at the world market. In the Badakhshan Prov., gem-quality kunzite crystals, up to 50 cm. long and 10 kg. weight was found. In the Laghman Prov. there is the deposit Kulam with crystals of kunzite, up to 4x20x45 cm., and transparent crystals of hiddenite, up to 10 cm. long. To the north from Jelalabad, crystals of spodumene of green, blue and yellow color, up to 1 m. long, and transparent crystals of kunzite, up to 40 cm. long at the deposit Mawi, were found. In India, apple-green spodumene and lilac kunzite, together with pink tourmaline, are found in lithium pegmatites to the north-east from Ajmere, Rajasthan State. At the placers of Sri Lanka, they find hiddenite of lemon-green hue. Among the other countries of this region they extract gem-quality spodumene in Myanmar and Pakistan. In China, in the Mongol Altai Mts., in pegmatites of the Xinjiang Autonomous Territory, near Koktogai, they found hiddenite crystals of gem-quality, up to 20 cm. in length.

In 1877, in Brazil, in Minas Gerais State, the most significant deposits of spodumene were discovered. In 1910, the biggest known crystal of kunzite, 110 kg. weight, was found there. In 1968, in the same state, at the deposit Córrego do Urucum, near Governador Valadares, they extracted crystals of noble spodumene, up to 2 m. long; and at the San Jose de Sapphira mine – kunzite. In the region of Itatiahia, at the deposit Conselhieiro Peña hiddenite was extracted. At the Urupuca mine, near Santa Maria do Suasui, a transparent crystal of kunzite 7.41 kg., 31.1x15.7x9.7 cm. in size, was found; it was sent to the collection of the Smiths. Inst., Wash. At the same deposit kunzite was found, which displayed the effect of cat’s-eye after cut. Big spodumene crystals are typical for deposits of the U.S.A. In North Carolina the first noble spodumene was found. In 1879, at the deposits Hiddenite Mine and Kings Mt., Alexander Co., hiddenite was found as transparent crystals up to 7x2 cm. in size; cut stones up to 9.29 ct. were made from them. In California kunzite at the deposit Pala Chief, San Diego Co., in 1903 was found. They extracted transparent crystals, up to 36x13 cm. in size there, and in the bigger crystals (up to 60 kg.) there were transparent parts up to 150 ct., from which cut stones up to 215 and 177 ct. were made. They found also hiddenite there. In South Dakota, the best deposit are Etta mine, Pennington Co., and Tin Mt. quarry, Custer Co., unique crystals of kunzite were found. The first of them was 14.33x0.8 m. in size and 28.43 ton; the second one – 12.8x1.83x0.91 m. in size and 66.1 ton; the third one – 16 m. long and 90 tons; and the biggest one – 14x2 m. in size and 100 tons. However, such crystals are usually non-transparent and possess a few of gem rough material. Together with kunzite they extract hiddenite there. In Maine State, at the Lover Pit deposit, near Newry, they find sometimes spodumene cat’s-eye. Besides, gem-quality spodumene was also found at deposits of other states.

Unique Crystals. In museum collections transparent crystals of hiddenites are in the Kunst. Hist. Museum, Vienna – 3x0.6x0.6 cm. in size; in the AMNH, N.Y. – 6.8x1.4x0.8 cm. in size; in the Sorb. Coll. Univ., Paris – 60 cm. long, from a deposit of Jelalabad, Afghanistan. The transparent crystal of kunzite, 1.2 kg. weight, of beautiful violet color, was also found there. In the Nat. Hist. Museum Houston, Texas, there is the biggest crystal of transparent kunzite, which was found in the U.S.A., 30 cm. long – it was found at the deposit Pala Chief Mine, California. In the Smiths. Inst., Wash., a transparent crystal of Brazilian kunzite 880 ct. is kept; and in the Museum Harvard Univ., the U.S.A. there is a unique crystal of kunzite from the deposit Pala Chief Mine, California, 2.2 kg. In the Museum Rio de Janeiro., Brazil, a crystal of kunzite 7.41 kg. is exhibited. Another kunzite crystal, 15x5.1x4.9 cm. in size and 1 kg., also from Brazil, was cut into pieces they faceted four stones with general weight 2,087 ct. from it.

Synonyms. Hiddenite – Lithium emerald | Spodumene emerald.

Kunzite – Lithium amethyst (Lithionamethyst ) | Cali- fornian iris | Amethyst spodumene.

Quality improvement. Many weakly colored spodumene loose their color in the direct sunlight. With gamma rays their color can be restored. Colorless and green crystals become pink after it; pink crystals receive yellow or green color. After neutron irradiation pale colored crystals of spodumenes become brown-orange to green-yellow in color. Heating up to the temperature of 500°C makes green crystals colorless, and brownish and greenish-violet crystals can be improved with heating up to 150°C.

Cut Gems. Spodumene as a gemstone has been used only since the end of the 20th cent. It is difficult for cutting because of its perfect cleavage; it is crackled under high temperature. The most popular shape of its faceting is a step-cut, more rare – a brilliant-cut one. To receive the most intensive tone the table facet of the stone should be placed under the right angle to the prism edge. In the British Museum, London they expose faceted kunzite – 61.7 ct. and hiddenite – 2.5 ct. The biggest faceted hiddenite was 9.29 ct. In the Smiths. Inst., Wash., there are 3 faceted stone of kunzite from Brazil, 880; 663 and 297 ct. and also one stone from California – 177 ct., as well as a yellow stone from Brazil – 327 ct. In the Nat. Hist. Museum, Denver, there is a faceted kunzite from Brazil, 296.7 ct. In private collections there are faceted kunzites from 500 up to more than 1000 ct. The biggest faceted spodumene of yellow-brownish tone is 1,800 ct.; it is kept in the Royal Ontario Museum. The sample of carving on kunzite is a figure, 137 mm. high, and 6,000 ct., in one of the private collections of the U.S.A. There is known a cut kunzite with the effect of cat’s-eye, 35.9 ct., another stone from Brazil is 113.32 ct. Among unique jewelries we should mention the pearls necklace with faceted spodumene, 396.3 ct. from the Smiths. Inst., Wash., and also the ring by of Tiffany & Company in the U.S.A. with kunzite, 52.62 ct. mounted among 104 brilliants, general weight 2.63 ct.

Synthesis. There is information about receiving of synthetic spodumene. Synthetic hiddenite in crystals, as material for imitation of emerald, is made with the method of hydrothermal synthesis on basic forms.

Similar Gemstones & Imitations. Similar to hiddenite there are such gemstones as: verdelite, diopside, emerald, chrysolite, chrysoberyl. Similar to kunzite there are: amethyst, vorobeyevite, petalite, rose quartz, rubellite, sapphire, scapolite, topaz and euclase. As imitations of spodumene they use colored glass, as well as synthetic materials: spodumene, spinel, phianite and synthetic garnets.

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