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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

LAZULITE, GROUP: LAZULITE, SCORZALITE


LAZULITE group (Lazulith—Lazulite—Ћазулит) (Widenmann, 1791 in Klaproth, M.H. 1795), from Lat. “lazulum”, Arabic “azul” or Pers. “lazhuward” – blue, is alluding to its color, and “lithos” – stone. Here also scorzalite is described, which forms an isomorphic row with lasulite.

Composition & Properties. Phosphate – Mg2Al2[(OH)2|(PO4)2], monoclinic system. Hardness 5-6. Density 3.1-3.2. Glass luster. Fragile. Lazulite is usually represented with complete grained masses, rarely they find its sharp-pyramidal crystals. Translucent to non-transparent, rarely transparent. Color: from thick blue to light bluish-green, yellow-green and dark green. Its color is stable because of the admixture of iron. It displays strong pleochroism from dark blue to colorless. Lazulite doesn’t form large crystals, that are why it is not especially popular among jewelers. However, it is widespread and is extracted as ornamental material at deposits of other gemstones.

Deposits. It is found in metamorphic rocks, in quartz and pegmatite veins, especially in quartzites. In Russia, lazulite in the form of accumulations, available for jewelry processing, is known in the Polar Urals, in quartz veins of the Longotyugan deposit, Marun Keu Ridge. It forms impregnation and nodular accumulations up to 20x30 cm. in size in hematite and kyanite secondary quartzites. In the Subpolar Urals Mts., gemquality lazulite was discovered in the upper reaches of the Balban-Yu River, in the zone 20 km. long, from the Narodnaya Mt. to the Chernyi Ridge with Chernoye deposit. Its isolations up to 20 cm. in size and also separate crystals up to 8 cm. long are found in quartz veins among quartzites. The largest accumulations of light blue and pale blue with greenish tone lazulite were found at the deposits Zhelannoye, Maldy Nyrd, Starukha Iz and Sura Iz. In East Siberia, lazulite was discovered from the South Siberia – Taseevskoye deposit; to north-east from Baikal Lake – at the Mamskoye deposit, near Bodaibo; on the Baikal-Patomskoye Plateau – in the basins of the rivers Vitim, Bartshikha, Bol’shaya Chuya; in the and East Sayan Mts. – in pegmatites at Gol’tsovoye deposit; also in Buryatia Rep. – at the Kyakhtinskoye and Ichetui deposits, Jidinskiy Dist. At the last two mentioned deposits, isolations of lazulite reach 10 cm. in cross-section and can be used for cabochons. In Kazakhstan, findings of lazulite were registered at the Chokpartas deposit. In Sweden, lazulite crystals up to 12 cm. at the Hålsjöberget deposit, Värmland, are known. In Austria, in the Salzburg in alpine vein they found a crystal of lazulite 2.5 cm. in size, near Hollgraben and Werfen, and at the Kratzenberg deposit crystals were up to 4 cm. In Switzerland, in the East Alps, in the region of Stubachtal, also in Alpine veins, they found a translucent crystal lazulite up to 4 cm. In Slovakia, light bluish isolations of lazulite up to 3 cm. in size were found in quartz veins of the deposits Drázovce, near Nitra.

In Africa, ornamental lazulite was discovered in Angola, near Lobito; and also in Namibia and Congo (Kinshasa). On Central Madagascar, near Betafu, in Mt. Biti, occur translucent crystals of lazulite and blue quartz, their color depended on micro-inclusions of lazulite. In India, in the Jammu and Kashmir State (disputed area), translucent crystals yellow-green or green lazulite up to 7 cm. at deposits of the regions of Gilgit, Skardu and in near Chiläs, Kokhistan, were extracted. In the Mahäräshtra State, gem-quality lazulite at Bhandara deposit, near Nagpur, is found. In Bolivia, lazulite was discovered at the Unificada de Potosí mine, Potosí Dept., where they also found its pseudomorphs lazulite after orthoclase. In Brazil, they found gemquality transparent bright blue and green lazulite – berkeyite at the Serra do Espinhaso deposit, Minas Gerais, from which they make faceted stones up to 5 ct. In the region of Diamantina, gem-quality crystals of lazulite in quartz-kyanite-hematite veins among quartzites were discovered. Their pebbles of lazulite as additional material from diamond fields are extracted. In Bahia, large transparent crystals of lazulite at the Minas Do Rio De Contas (Rio de Contas) deposit was found. In the U.S.A. lazulite occur in New Hampshire, in the region of White Mountain and North Gorton, where they made faceted stones up to 78.4 ct. In Georgia, they also discovered gem-quality lazulite with crystals up to 3.5 cm. at the Graves Mountain deposit, Lincoln Co. In North Carolina, material for cabochons was extracted near Crowder’s; in California – at the deposits Champion Mine and Mocalno, Mono Co. At the second one, the size of isolations of lazulite reached 15 cm. On Alaska, near the Canadian border, in the valley of the Yukon River, they found lazulite in the form of transparent blue and dark green crystals. In Canada, lazulite was discovered at the deposits Big Fish River and Rapid Creek, Yukon Prov., where they found crystals up to 5 cm. long and made faceted stones up to 2 ct.

Synonyms. Azurite, mist. | Amazonite-like feldspar | Blue feldspar | Gersbyite, after the discovery location near Gersby, Sweden, obs. | False lapis | Georgia lazulite, Amer. | Mollite, after C. von Moll, obs. | Light blue opal | Siderite, obs. | Asure spar | Light blue spar | Prismatic lazur spar | Azurite prismatic spar | Blue stone | Tyrolite, after the discovery location in the Tyrol, Austria | Voraulite, after the discovery location near Vorau, Austria.

Treatment. Lazulite is often cut in cabochon. Rare transparent crystals are available for faceting; stones are not more than 5 ct. In the Museum of Calgary, Canada, there is a faceted blue lazulite from Africa, 4.2 ct. in mass. In complete masses and impregnated into rock it is used as an ornamental stone.

Similarity. Lazulite looks like azurite, apatite, cordierite, lazurite, sodalite and turquoise.

Scorzalite (Scorzalit—Scorzalite——корцалит) (Pecora, W.T. & Fahey, J.J. 1949), after Evaristo Peña Scorza (b. 1899), a Brazil mineralogist. Phosphate – Fe2+Al2[(OH)2|(PO4)2], monoclinic system. Hardness 5-6.5. Density 3.2-3.3. Glass luster. Cleavage in one direction. It forms an isomorphic row with lazulite as ferrolazulite. It is found as solid grained aggregates, sometimes, as sharp-pyramidal crystals. Color: dark azure-blue to light blue-green. Translucent to non-transparent. It is found in quartzites and sericitic schists at contacts rich phosphates granite pegmatites. In Russia, ornamental-quality scorzalite was found together with lazulite in quartzites of the Subpolar Urals Mts. and in the East Sayan Mts., at the Gol’tsovoye deposit. In Europe, findings of scorzalite, available for cutting in cabochons, were known in Sweden, at the deposits Långban and Horrsjöberg, near Thorsby. On Madagascar, scorzalite was discovered in pegmatites Betafo Dist., in the form of large crystals with translucent segments. In Zimbabwe, it was discovered at the Buranga deposit, near Kadoma (form. Gatumba). In Japan, scorzalite is known at the Tanokamiyama deposit, Sega Pref. In Brazil, in Minas Gerais State, scorzalite was discovered at the Córrego do Frio deposit in 1947. Its crystals available for faceting, were ex-racted at placers near Diamantina, too. In the U.S.A., in South Dakota, scorzalite in the Caster Co. was discovered, in North Carolina in the Gaston Co., and in New Hampshire, they made faceted stones up to 78.4 ct. from of the regions North Gorton and White Mountain.

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