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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

SCAPOLITE


SCAPOLITE (Skapolith—Scapolite——каполит) (d’Andrada J.B., 1800), from Gk. “skapos” – a shaft, is alluding to the prismatic shape of the crystal. In western gemology scapolite is often called wernerite, after the Germ. mineralogist A.G. Werner (1750-1817). In mineralogy two varieties of scapolite are used: marialite and meionite. These names and for intermediate varieties of the same row – dipyre and mizzonite – are used in mineralogy only. Marialite (von Rath, G. 1866), after Maria Rose, wife of Gerhard von Rath (1830-1888), Professor of Mineralogy, University of Bonn, Germany. Meionite (Haüy, R.-J. 1801), from Gk. “meion” – less, alluding to the less acute pyramidal terminations on its crystals in comparison with vesuvianite.

Composition & Properties. Scapolite is a silicate of changing composition from marialite – Na4[Cl|Al3Si9O24] to meionite – Ca4[CO3|Al6Si6O24], and subclass carcasses silicates, tetragonal system. Hardness 6-6.5. Density 2.5-2.7. Cleavage good in two directions. Fragile. Glass luster to pearl one in joints. Scapolite is found as columnar crystals with square section up to 50x20 cm. in size. Not rarely they are rather big, and display radial or fibrous aggregates as well as solid grained masses. Translucent to transparent. Color: colorless, white, bluish-gray, greenish-yellow, yellow, brown, orange-brown, light blue to violet, more rarely pink, red. Colored varieties of transparent noble scapolite display strong pleochroism: pink and violet – from dark blue to lavender-blue, colorless and pale yellow – from colorless to pale yellow and yellow. For cut scapolite it is typical to display the effect of cat’s-eye, asterism and opalescence. Rare finding is translucent black scapolite with the effect of cat’s-eye, produced with inclusions of pyrrhotite in channels along the main axis. Colored varieties of noble scapolite not rarely have their own trade names: transparent pink – pink scapolite, pink with opalescencerose moonstone, transparent violet or yellow – petschit, gray-green or greenish-yellow – stroganovite, nontransparent blue or violet – glaucolite, lilac variety of meionite – nuttalite. Solid product of decomposition of scapolite – purple-red pinite or wilsonite is an ornamental variety like jades.

Deposits. Scapolite is formed in magmatic rocks, in the process of contact metasomatism, in pegmatites and in hydrothermal veins. As a gemstone it has been known since 1913, when in Myanmar (Burma) and in ruby mines of Mogok transparent pink scapolite had been found. In Russia jewelry-ornamental scapolite of gray-green or greenish-yellow tone – stroganovite is known in Pribaikalia, at the deposit Slyudyanka – as crystals, up to 1.5 m. long. There also massive violet-blue glaucolite is found. In Yakutia massive scapolite rock – tokurit was discovered on the Tokur River, Anabar massif. It has beautiful red-green color, it is composed mainly with bright red and bright green scapolite (80-90%), chrysolite (10-20%) and contains small insets of andradite. This rock consists of blocks, up to 80 cm. wide; it can be polished. It can be a perspective ornamental stone. In Tadzhikistan gem-quality scapolite was discovered in the East Pamirs Mts. to the west from the Murghob settlement, on the water-shed of the rivers Zor Burulyuk and Kukurt, in albitescapolite veins of the deposit Kukurt; in miarolitic pegmatites of the deposits Pereval’noye and Polykhromnoye, and also in cavities of quartz veins in marbles at the deposits Redkoye and Osenneye, in the early of 1980s. At the deposit Kukurt crystals of scapolite reach 10x4 cm., violet hue dominates there, more rare they are yellow. In composition they are close to marialite. At the other deposits of the Turakuloma Ridge similar transparent scapolite crystals are not more than 5 cm. long. Cut stones made from them reach the weight of 30-50 ct. In cabochons of pink scapolite, because of its hollow channels, the effect of cat’s-eye is displayed. In South Kyrgyzstan, at the massif Zardalek, in the upper reaches of the Soch River, in garnet rocks scapolite forms radial-rayed aggregates, which look like flowers, – scapolite sun, up to 8 cm. in cross-section. In Finland, findings of scapolite up to 15 cm. size are registered on the Parainen Is. (form. Pargas). In Sweden, at the deposit Gullsjö, Våstra Götaland, they found light blue crystals of meionite. In Switzerland, near Tremorgio Lake, Ticino canton, big straw-yellow crystals were extracted. In Italy, transparent crystals of marialite at the deposit Pianura, near Naples, are found. In Germany, crystals scapolite extract on the deposit Laacher See, Rhineland-Palatiate

In Tanzania, gem-quality golden-yellow, pink and purple scapolite in crystals, up to 5 cm. long, was extracted at the placers on the Umba River. At the same region, near Dodoma, they found gem-quality transparent violet and yellow petschit, and transparent pale yellow crystals of marialite up to 10 cm. long at the deposit Mpwa-Mpwa. Scapolite from Tanzania with asterism and the effect of cat’s-eye have channels along the main axis. In colorless scapolite they are filled with pyrrhotite plates, and in yellow one – with hematite and lepidocrocite flakes, which produce sometimes aventurescence. Cut yellow scapolite from Tanzania reached the weight of 35 ct. In Kenya, scapolite of different colors – from pink to purple, golden and blue as well as red-brown. In cabochon they display the effect of cat’s-eye because of fibrous inclusions. Generally they produce here not very big cut stones, up to 3 ct.; but some pieces reached even 73 ct. In Mozambique, they find crystals of purple hue, but at the deposit Entre Rios, near Malem, crystals are yellow. On Madagascar, near Tsarasaotra, they found yellow noble scapolite in 1920. Near Taolanaro there are transparent crystals up to 70 cm. long. In Myanmar (Burma), yellow, purple, violet and light blue scapolite was extracted, as well as rose moonstone and violet-blue scapolite with the effect of cat’s-eye, which was displayed after cut. On Sri Lanka, near Ratnapura, they found colorless scapolite with asterism at the placers, and near Balangod they found yellow scapolite with the effect of cat’s-eye, which appeared because of inclusions of pyrrhotite. In China, in the Hainan Prov., noble scapolite of purple hue is extracted at the deposit Kunrun. In Canada, at the deposit Bear Lake, Québec and Bancroft, Ontario Prov., findings of lemon-yellow noble scapolite in crystals, up to 35 cm. in size, are nor rare. Here, near Wakefield, they found cacoclasite – pseudomrph on scapolite, represented with the mixture of grossular, calcite and prehnite. In the U.S.A. masses of yellow scapolite and its crystals were discovered at the Crestmore quarry, Riverside Co., California; in the Chelmsford locality – Worchester Co., Massachusetts; in the Sussex Co., New Jersey. In Brazil, deposits of transparent scapolite are situated in Minas Gerais State, near Governador Valadares; in the Espírito Santo State, in the region of Aracruza; and also in the Bahia State. There, in pegmatites, the size of honey-yellow crystals reached 40x10 cm. After cut they received gemstones up to 30 ct. In Mexico, at the deposit La Panchita, in the Oaxaka State, they found rather good crystals of scapolite up to 25 cm. long.

Synonyms. Algerite, after the discovery location in Algeria, New Jersey, the U.S.A., micas pseudomorph after scapolite | Arcticite (arctite), after the discovery location in Ivigtut (Arsuk Fjord), South Greenland | Bergmanntite | Cacoclasite, from Gk. “cacos” – bad and “clasis” – a crackle | Chelmsfordite, after Chelmsford in Massachusetts, the U.S.A. | Couseranit, after the discovery location near Couseran, France | Dipyre (dipyrite), from Gk. “di” – two and “pyr” – fire, because of its double behavior under heating – melting and phosphorescence | Ekebergit, after the Swedish scientist A.G. Ekeberg | Fuscit, obs. | Glaucolite, from Gk. “glakos” – green-blue, according its color | White hyacinth | Leucolite, from Gk. | Luscite, obs. | Mizzonite, from Gk. “mizzon” – big, because the ratio of its main axes is bigger than in meionite | Nuttalite, after the Amer. mineralogist Th. Nuttal | Ontariolite, after the discovery location in Ontario, Canada | Paralogit | Parantine (paranthine) | Petschit, after the researcher Y. Petsch | Porcellanite (porzelanit) | Rabdolite, from Gk. “rabdos” – stick, rod, after the shape of its crystals | Rapidolite, from Gk. “rapis” – bow, after its shape | Riponite, after the deposit Ripon, Québec, Canada | Porcelain spar | Stroganovite, after the Russ. manufacturer A.G. Stroganoff | Tetraclasite, from Gk. “tetra” – four and “clasis” – a crackle, because of its cleavage | Wilsonite, after the Amer. mineralogist M.M. Wilson.

Scapolite cat’s-eye – Black scapolite cat’s-eye | Blue scapolite cat’s-eye | Pink scapolite cat’s-eye | Yellow scapolite cat’s-eye.

Quality improvement. To strengthen the color of scapolite gamma-irradiation is used. In that case yellow crystals from alkali metasomatic rocks become lilac, are lilac crystals from pegmatites receive more thick color. However, such scapolite can loose their color in the sunlight, but naturally colored analogues keep their color. Ultraviolet irradiation, just the opposite, weakens the color – and lilac scapolite becomes pink, and yellow one – colorless.

Cut Gems. Gem-quality material comes mainly from Myanmar. It is faceted in brilliant or stepped patterns of faceting and half-transparent stone is cut in cabochons. After cut lilac varieties reach 50 ct., yellow ones – more than 50 ct., colorless ones – up to several hundreds of ct. The most highly evaluated variety is light blue scapolite with the effect of cat’s-eye and asterism, which it displays after cut. Among the biggest faceted stones we should mention the orange-red scapolite with asterism from Sri Lanka, 118 ct.; and the light yellow one from Tanzania, 130 ct. In the Smiths. Inst., Wash. there are several cut scapolites: 12.3 ct. and the colorless cabochon with the effect of cat’s-eye – 29.9 ct. There is also the yellow stone from Brazil – 29 ct. and rose cat’s-eye from Sri Lanka – 17.3 ct. In Canada, in the Royal Ontario Museum, there are faceted scapolites from Myanmar: the colorless one – 65.63 ct., the pink one – 7.91 ct., and also stones with the effect of cat’s-eye – the gray one – 18.8 ct. and the pink one – 18.3 ct. There are also two yellow scapolites from Brazil – 28.4 and 57.6 ct.

Similar Gemstones & Imitations. It looks like amblygonite, beryl, amethyst, citrine, spodumene, topaz and chrysoberyl. Massive violet-blue glaucolite looks like lazurite, it was sold sometimes under its name. For imitation of scapolite they use sometimes quartz or glass.

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