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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

FLUORITE


FLUORITE (Fluorit—Fluorite—‘люорит) (Agricola, G. 1529), from Lat. “fluere”, to flow, alluding to its readily fusible nature and use as a flux in smelting. That’s why it is called also fluor spar or fluss.

Composition & Properties. Halide – CaF2, cubic system. Hardness 4. Density 3.0-3.3. Glass luster to greasy one. Cleavage perfect in four directions. Fragile. The most impressive mineral from halides and a popular gemstone. It is found as well-formed crystals of isometric shape, as well as dense grained, radial-rayed and columnar aggregates. For the fluorite crystals twin growing is typical. It is transparent to translucence. It can be colorless or colored in various tones or multicolored. Color is often distributed in zones, in aggregates it can be stripped or with spots. The nature of its color is complicated; it often depends not on admixtures but on defects of crystal structure. Admixtures of rare-earth elements lead to fluorescence of fluorite in U.V.-rays. Inclusion of bitumen gives bluish-black color to a variety of fluorite called antozonite. Green variety is called chrome-fluorite. Under annealing fluorite receives green shining, that’s why it is called chlorophane, pyro-emerald, pyrophane. Massive stripped variety with gradual differentiation of color from red to orange and from yellow to violet is called rainbow fluorite. Massive purple-red variety was called litoslazuli in the ancient times. Dense fluorite of different colors, used in glyptic and stone carving, has the trademark cabra stone in the world market. There is also fluorite hair stone with inclusions of needle tourmaline.

Deposits. Fluorite is widespread mineral of pegmatites and hydrothermal veins. In Russia, in the Northern Caucasus, collection mineral druses were found, including druses with fluorite crystals at the Belorechenskoye deposit and at the Tyrnyauz mine, near Nal’chik. In East Transbaikalia, in the Chita Region, there are varieties of fluorite of different colors for decorative work of art at the deposits Abagaitui, Solonechnoye, Usugli, Dul’durga and others. In the same region, at the Kalangui deposit, especial cockade structures of stripped fluorite were found; and at the Klichka deposit wonderful collection samples were found. In the Primorskiy Region unique crystals of dark-green fluorite up to 35 cm. at the Dal’negorskoye deposit are found. Among the other fluorite deposits in the Primorskiy Region we should mention Pogranichnoye, Voznesenskoye and Silinskoye, near Kavalerovo, and in the Khabarovsk Region – Khinganskoye. In the Magadan Region, light green crystals up to 16 cm. occurs at Canyon deposit. In the south-eastern part of the Amur Region, to the southeast from the railway station Arkhara, there is Boguchanskoye deposit of green fluorite, which was opened as early as in 1894. In Tadzhikistan, the best crystals of optical fluorite were excavated in the Zeravshanskiy Khrebet, at the Kulikolon deposit in 1933; now, that deposit is worked out. The biggest from its colorless crystals of optical quality had more than 24 kg. and was 276x258x184 cm. in size. In the Hissar Mts., there is the Takob deposit, where fluorite crystals were up to 10 cm. in size. Another deposit of the same type is Bazar Dara in the South-East Pamirs Mts. There transparent crystals, up to 70 cm. in size at the cube edge were extracted. In Uzbekistan, fluorite for decorative work of art was extracted at the Aurakhmat deposit, near Toshkent (Tashkent), and at the Suppatash deposit, at the Kuraminskiy Mts., near the railway station of Angren. In South Kyrgyzstan, collection fluorite crystals at the Kadamdzhai deposit in Fergana Valley, were found, and at the Chauvai mercury deposit, near Osh. In Kazakhstan, large crystals of optical fluorite were extracted from cavity in pegmatite at the Kent deposit, near Karkaralinsk which is worked out now. One of these crystals, 330 kg., is kept in the Mining Museum, SPb. now. Superb collection fluorite occurs also at the deposits, Aqshataü, East Kounrad, Quara Oba (Karaoba), Keremet-Tas and others. Rather rich fluorite deposits are exploited in Mongolia and China. In Europe, classical deposits of colored gem-quality fluorite are known in Great Britain, where they have been exploited for more than 1,500 years. Main of them are situated in the south-western part of England, on the Cornwall Penin., e.g. Caradon mines; in the central part of Derbyshire, on the coast of Scotland. Transparent crystals of violet fluorite, up to 30 cm. at Wheal Mary, Menbeniot, were found; also at Hates deposit, near Olsten, Cumbria. Their translucent fluorite for decorative work of art is extracted, which is known under the trademark cand. In Derbyshire, blue variety of fluorite is extracted; it is called blue John; it had wavy stripes. Another variety there is light yellow Derbyshire spar or Ashover spar. In Norway, in the region of Kongsberg, colorless, green and violet crystals have size up to 20 cm. In Germany, fluorite deposits are in Saxony, near Freiberg – Halsbrüke. There, in the Erzgebirge, crystals up to 60 cm. in size were found, and near Annaberg, – golden-yellow, up to 6 cm. in size. In France, at the Chamonix deposit, Haute-Savoie Dept., pink fluorite in crystals, up to 18 cm. in size, is found. In alpine veins of Switzerland, in the Uri Canton there were perfect crystals of pink fluorite up to 18 cm. In Spain, violet fluorite crystals, to 10 cm. in size at the mines La Cabaña, La Collada and Villabona, Asturias Prov., were found. In Italy, to the north from Bergamo, there is the Zongo deposit, where red-violet fluorite crystals were found, up to 42 cm. In Southwest Africa, in Namibia, at the Okasu deposit near Ochiwarongo, green fluorite for decorative work of art is extracted; it has the trademark Africa-emerald or South-African emerald. In South Africa, there are big quantities of fluorite for decorative work of art at the Buffalo deposit, Eastern Cape Prov. In Mozambique, in the Alto Ligonha region, fluorite crystals, up to 10 cm. in pegmatites were found. In China, fluorite crystals, up to 15 cm. at the Pingwu deposit, Sichuan Prov., were extracted. Similar deposits are in Korea, Pakistan, Australia and other countries.

In the U.S.A., superb violet cubes fluorite up to 50 cm. at the Elmwood mine, Jasper Co., Tennessee, are extracted; in New Mexico violet fluorite in crystals up to 2 m. and to 16 tons at the Globe mine, Petaca Dist., were found; in New Hampshire, at the Westmoreland deposit – pale green fluorite with transparent crystals up to 25 cm., from which faceted gems are received to 200 ct. In Canada, beautiful dark violet crystals of antozonite at the Bancroft deposit, Ontario Prov., were found. It is a variety of fluorite with a special stink, which depends on free emanation fluorine; that’s why such fluorite is called stinking spar. In Mexico, emerald-green crystals up to 10 cm. at the Gibraltar mine, Chihuahua, are found; in the Guanajuato State – crystals of red fluorite. The biggest quantity of fluorite is extracted at the Las Quenvas mine. In Peru, crystals of pink fluorite up to 7 cm. at the Uanzala mine, Uanuco Dept., were found; and green crystals up to 15 cm. occurs in the Pasto Bueno Dist., La Libertad Dept.

Synonyms. Androdamant | Kawk, Engl. local name | Liparite – from Gk. “liparos” – shining | Lysspat, Germ. | Plavik, Russ. | Pyrosmaragd | Fluoric spar | Glassy spar | Plavikovyi spar, Russ.

Red – Erzblüte, Germ. | False ruby | Vermeil, the general commercial name of orange-red garnet, spinel or zircon.

Yellow – Ashover yellow spar | Derbyshire stone | Bohemian topaz | False topaz.

Green – Water aquamarine | Water beryl, obs. | Beryllflus | ~ emerald (smaragd): African ~, Bohemian ~, evening ~, false ~, matrix ~, pseudo ~, water ~| Carthaginian esmeralda, according the place of finding | False esmeralda | Green John | Murin, anc. Roman. | Green quartz, obs.

Blue – Cyanus, obs. | False sapphire.

Violet —Derbyshire amethyst | False amethyst | Derbystone, according the place of finding.

Multicolored – Ore flower | Rainbow fluorite.

Quality improvement. Color of fluorite is non-stable under high temperature. Annealing of fluorite to 700°C weakens dark violet color or even annihilated it to white one. The most stable to annealing is purple color. As a result of gamma rays, colorless fluorite receives green or blue color, and blue fluorite becomes purple-red.

Cut Gems. Fluorite was known in the ancient times. According the supposition of Russian mineralogist N.P. Scheglov, Murrhins vases (“murrha” Lat. – fluorite) from Ancient Rome were cut, obviously, from fluorite. Hungarian archaeologists found a bracelet and a necklace of the 10-11th cent. made from fluorite beads near Sekeshfehervara. Each of them is covered with 12 facets and has an even hole. Thanks to easiness of cut and its bright color, fluorite was often used for the imitation of more expensive gemstones, such as amethyst, emerald, ruby, sapphire, topaz. Plates of fluorite, saturated with resins, were used for the decoration of interiors under the trademark ornamental spar. In Russia, fluorite for decorative work of art has been used since the 18th cent., for grinding works and souvenirs mainly: vases, boxes, bottles, ashtrays and mosaics. It was cut in cabochon or faceted up to 200 ct., mainly for collections. In the Pavlovsk Palace not far from St Petersburg, there are vases and other cut work of art from English fluorite. Two vases from that fluorite are in the Geological Museum in London. In the collection of the Smiths. Inst. Wash, cut fluorites of all the colors of the rainbow are exhibited: pink from Korea 492 and 354 ct.; pale yellow 354 ct., pink from Pakistan 248.8 ct.; red from England 118 ct. From American samples there are cut fluorites from Illinois – violet 351 and 111.2 ct., from New Hampshire – green 124.5 ct., from Tennessee – yellow 874 ct. and 535.8 ct. The biggest cut blue fluorite had weight 3,965.35 ct.

Legends. Astrologers considered fluorite as a lucky stone for the people who were born under the sign of Pisces. In the U.S.A., fluorite is an official symbol of Illinois.

Synthesis. Unique optical properties of fluorite include high transparency in a broad wave scale from ultraviolet to infrared parts of the spectrum. It explains the necessity of its industrial synthesis. Synthetic fluorite is received with the method of melting or with the pressing from powder. With the hot pressing of fluorite powder they receive optical crystal ceramics. It is polycrystalline material, which gives the possibility to receive product of any forms, up to some meters in size. So transparent ceramics is made for jewelry purposes – it is called yttralox – from synthetic yttrium oxide (90%) and synthetic thorium oxide (10%). Among the other synthetic fluorides, similar to fluorite, there are: lithium fluoride, colorless up to yellow, hardness 5.5-6; manganese fluoride, brown - pink, hardness 4; and also cadmium fluoride and rubidium fluoride, which are used for jewelry purposes.

Similar Gemstones. Fluorite is similar in color with many other gemstones, including amethyst, apatite, baryte, but it differs from them in hardness.

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