Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia



Alkali Feldspars group – properties. Hardness 6. Density 2.6. Cleavage in two directions. Glass luster, pearl one on cleavage planes. Alkali feldspars are found as short-columnar crystals, sometimes plate ones. Color: pale rose, gray, yellowish, reddish, brownish, greenish-blue and colorless. Non-transparent, translucent to transparent. Jewelry-ornamental stones are their varieties, which display bright color and effects of aventurescence, asterism, iridescence, opalescence and cat’s-eye in cabochons. It is typical for them to have ornamental inclusions: light colored perthites – products of decomposition of hard solution of albite – microclin-perthite; or graphic accretions with quartzmyrmekites. In pegmatites, feldspars form giant-crystalline aggregates, separate parts of which can be up to 10 tons. In rocks, they are rock-forming minerals, sometimes as bi accumulations, such as oval bodies of microcline in rapakivi granite. There are also cryptocrystalline jasper-like masses composing with feldspars.

Microcline (Microklin—Microcline—Микроклин) (Breithaupt, A. 1830), from Gk. “micros” – small and “clino” – to incline, is alluding to the small deviation of its intersecting cleavages from 90°. Composition – K[AlSi3O8], triclinic system. Microcline as an ornamental stone is hardly used. But its carnal-red crystals with perthites, inclusions of albite and pearl luster on cleavage planes can be cut in cabochons and are used in stone-carving. Such microcline, sometimes, is called aventurine spar by mistake. As colored stones, such varieties of microcline are of special interest: microcline moonstone, sunstone, amazonite and orange-rose bertite. Sunstone displays aventurescence, which depends on regularly oriented inclusions of the thinnest flakes of hematite, which give orange-red hue to this stone, as well as chatoyant luster in reflected light.

Amazonite is a variety of green or light blue-green microcline with white inclusions – perthites of albite. They are found as giant-crystalline aggregates in granite-pegmatites or as rock-forming mineral in amazonite granite. In pegmatites, the size of separate fragments of amazonite can reach some meters in cross-section. Non-transparent, weakly translucent. Green color of amazonite depends on the admixture of lead, light blue one – on the admixture of iron. In the light its color is stable, it isn’t transformed under heating to 300-500°C, but under higher temperature it is weakened and lost and it can’t be restored. Amazonite is well processed and polished. Its defect is complete cleavage, which decreases the size of blocks available for processing. Ornamental and technological properties of amazonite in high degree are depending on the size and the character of distribution of perthites of albite, which quantity can reach 25% of the volume of a stone. The most valuable are its bright colored varieties without perthites – amazonite jade or with the thinnest perthites, which give the iridescencegreen moonstone.

Graphic pegmatite is a variety of microcline. This ornamental stone contains spindle-like inclusions of quartzichthyoglyphs (from Gk. “ichthyos” – a fish and “glypo” – to carve, after the shape resembling fishes). They look like Hebrew letters, that’s why such microcline is called graphic granite, Jewish granite or Jewish stone. The most ornamental varieties of graphic pegmatite have clear patterns composed with colorless, gray or smoky ichthyoglyphs on white, light gray or light rose to carnal-red background of microcline. The orientation of these inclusions is regular; it is formed with the structure of microcline. Their size varies in a broad scale; their shape depends on the direction of a cut in a stone. The width of zones enriched with “graphics” in pegmatites can reach 10 m.

Deposits. Microcline is a widespread mineral of granites and granite pegmatites. In Russia, ornamental microcline is extracted from pegmatites of Northern Karelia, the Urals and Transbaikalia. In Karelia, sunstone is found in pegmatites near the Ambarnyi Station, on the shore of the White Sea; on the Sedlovatyi Is., in the Kandalaksha Bay; and on islands of the Onega Bay. In the Middle Urals, sunstone is known at the Potaninskoye deposit, Kyshtym Dist. Its separate fragments up to 10-20 cm. long were found in miarolite cavities of alkali pegmatites of the Vishnevye and Ilmeny Mts. Sometimes, they observed the composition of the effects of sunstone and moonstone there. In Pribaikalia, findings of sunstone in the Pad’ Ulungui, Slyudyanka area, are known, and also at the Ol’khonskoye deposit in pegmatites with amazonite and rose quartz. In Buryatia Rep,. deposits of sunstone are situated in the low reaches of the Selenga River, near Ulan Ude; and in pegmatites of East Transbaikalia. In Norway, ornamental varieties of microcline are represented with deposits of sunstone – Bjerdammen, Tvedestrand, Havredal and Moss. At the Moss deposit, a crystal of microcline up to 10 m. was found. In Finland, at the Haapaluoma deposit sizes of microcline crystals reached 4 m. The best deposits of sunstone are on Sri Lanka, near Kandy and Dumbara, Ratnapura region; and near Ambalangoda. In the U.S.A., sunstone is extracted in Oregon, at a deposit to the northwest from Lakeview, Lake Co. In Canada, on the Labrador Penin., also they extracted microcline moonstone.

Amazonite, as an ornamental stone, is found in three types of granite pegmatites: rare-earth, rare-metal and miarolitic. In Russia, they are known on the Kola Penin., in the Keivy Range, where more than 200 of pegmatite veins with amazonite were discovered and the resources of ornamental amazonite at the Ploskogorskoye deposit were calculated. Not far from it, at Parusnaya Mt., there are collection druses of amazonite with the size of crystals up to 5 cm. In the South Urals, amazonite was discovered in the Ilmeny Mts., near Miass, more than at 20 mines. At one of them, even in the 18th cent., in an opened-cast mine they found a crystal of amazonite, 10x10 m. in size. The best Ural amazonite was extracted at the Lobachevskye mines and at Kriolitovaya mine (form. Gasberg). Nowadays, all these mines are situated in the territory of the State Ilmenian Mineralogical Reserve. In East Siberia, amazonite was found in the north of Buryatia Rep., in raremetal pegmatites of the North-Baikal Plateau. The most promising the deposits Abchada are there, with more than 20 amazonite pegmatite with beryl. Similar veins were discovered to the north-east from Baikal Lake, in the basin of the rivers Tsipa and Bambuika. In Western Pribaikalia, such pegmatites were discovered in the region of Slyudyanka, where crystals of amazonite reached 15 cm. in cross-section. One more deposit of amazonite in that region, also connected with pegmatites, is situated in the basin of the Upper Bira River, on the right bank of the Goujikit River. One of peg- matites is composed there almost completely with bright green amazonite, the size of its crystals reached 15x30 cm. To the south from Baikal Lake, amazonite pegmatites and amazonite granites were found in the East Sayan Mts. Ridge – in the basin of the Oka River and on the Bitu Jida River in the Hamar Daban Ridge. In the Chita Region amazonite granites were extracted at the deposits: Etyka, Orlovskoye and Spokoininskoye. In the same region there are massifs of amazonite granite: Achikanskiy and Tugrinskiy, where amazonite pegmatites are found.

In Tadzhikistan, in the East Pamirs Mts., in the region of Rang-Kul’ Lake, there is the Amazonitovoye deposit in pegmatites, with crystals of amazonite up to 30 cm. Amazonite in crystals up to 18x8x7 cm. was found also on massif Turpi at the East Karategin Ridge. In Kazakhstan, in the Jambul Region, they have explored several deposits of amazonite granites, a deposit Maikul’skoye is the largest one of then was in West Pribalkhashia. In Kyrgyzstan, deposits of amazonite pegmatites are known in the Isyk-Köl Lake Region, at the Ranges Inyl’chek and Soryjas, Karakol Dist. (form. Przheval’sk). In Mongolia, there is the Dzun Bain deposit of amazonite, near Ulan Bator. In Finland, near Muurame, they extract amazonite granite and use an orange-rose variety of microcline-bertite as an ornamental stone; also in crystals up to 12 m. at Kaatiala, Vaasa Prov. In Norway, pegmatites with amazonite are at the Tøredal deposit, Telemark, and at the Kragerø deposit. In Italy, at the Baveno deposit of amazonite, Piedmont, is known. In Africa, amazonite is known in Zimbabwe – in the Shimanda region; in Namibia – in pegmatites near Spitzkopje; in Kenya – at the Machakos deposit; in Tanzania – at the Luguruka deposit; in South Africa – near Capetown; and also in Mozambique. The biggest quantity of amazonite deposits is on Madagascar: Vakin Ankaratra and Manandriana, Antananarivo region; also near Makhabo, in the Andriamena vilage, at the Anjanabonoina deposit, near Ambatofotmkemo; and others. At the Ankofafa deposit, translucent crystals of amazonite up to 32 cm. are known.

In India, amazonite is extracted in small quantities in the Jammu and Kashmir State (disputed area), and also in the region of Chennai (form. Madras). In Myanmar (form. Burma), its findings are known near Mogok; in China – in the Sichuan Prov. In the U.S.A., there are several deposits of amazonite in Colorado, including those in Crystal Peak, Cameron Cone, Florissant and others, with crystals of amazonite, up to 50x36x13 cm. and 15 tons weight. There is also microcline moonstone. In Virginia, amazonite was extracted in pegmatites of the deposits Amelia Courthouse, Reserford and Moorefield, in Amelia Co. In Canada, in the Ontario Prov., there are deposits of amazonite – Lindock and Perry Sound. In Brazil, in Minas Gerais State amazonite is extracted from pegmatites at the deposits Joahíma, Pirakanimba and San Miguel. At the Córrego do Urukum deposit, near Governador Valadares, in pegmatite they found crystals of feldspar more than 10 tons in mass. Crystals of amazonite in these pegmatites reached 40 cm. long.

Graphic pegmatite is extracted as an additional material with pegmatites usually. In Russia, on the Kola Penin., numerous pegmatite veins with “graphics” are known in Western Keivy and in the south-west of the Penin., near Alakurtty. In Karelia, sections of graphic granite are found not rarely in mica pegmatites in the region of the railway station Chupa; and in Priladozhia – at the Brusnichnoye deposit, near the railway station of Novye Peski the resources of pegmatites with graphic granite have been calculated. Similar pegmatites are known in the Middle Urals – at the Murzinskie mines; in the South Urals – in the Potaniny Mts. In North Kazakhstan, the largest deposit of graphic granite is Zerendinkoye. The thickness of zones enriched with graphic granite in pegmatites can be up to 10 m., for instance in South Norway, in a vein near Kragerø.

Synonyms. Microcline – Ceramic feldspar | Red clouded feldspar | Triclinic feldspar | Feld stone.

Sunstone – Astrachanite, obs. | Oriental aventurine | Heliocite | Heliolite | Sparkling heliolite | Aventurine luster | Solnechnik, Old Russ.

Amazonite, as analogue of light green nephrite from the Amazon River, which was known under the name Amazon stone | Emerald edelspath | Colorado jade | Green microcline | Spar – from Swedish “feld” – field and Gk. “spate” – a plate, because it can be split into separate plates and because it was found in weathered masses in fields.

Graphic pegmatite, at first, was called pegmatite, from Gk. “pegma” – connection, link | Grammite | Runit | Schriftgranit, Germ. | Jewish spar | Alphabetic stone.

Treatment. The most popular variety of microcline as an ornamental stone is amazonite. It was known even in Ancient Egypt, because amazonite mines were extracted in Ethiopia. Adornments from amazonite were in the tomb of the Egyptian Pharaoh Tutankhamen (1392 B.C.), which was discovered near the ancient Thebes in 1922. In Russia, in the South Urals, in the Ilmeny Mts. amazonite was discovered in 1783. Since 1804, it has been extracted under the name of green feldspar, or emerald edelspath for the Yekaterinburg and, since 1831, also for the Peterhof lapidary factory. One of those mines, according an eye-witness, was founded in a giant crystal of amazonite. Unfortunately, that mine was destroyed, when the Trans-Siberian railroad was built. At the Peterhof lapidary factory from the extracted amazonite they made two pairs of vases for the State Hermitage SPb.: one pair – 27 cm. high, another one – 25 cm. high, as well as 4 tables: two –141x71 cm. in size, and another two – 123x71 cm. In the mosaic “Map of the U.S.S.R.”, which has received the Grand Prix of the Paris Exhibition in 1937, they made planes with Ilmenian amazonite. As a non-expensive stone, amazonite is used in a repetition work in manufacturing of stone adornments and souvenirs. Waste products from the enrichment of stone blocks with grit were used in Murmansk and Apatity to manufacture coating plates and as ornamental powder in wall panels.

Graphic pegmatite has been being used since the end of the 18th cent. – as insets in signets and in bigger work of art. In the State Hermitage, SPb., there are composed tables with this stone.

Legends. Amazonite was found in Scythian burial mounds in the territory from the low reaches of Don to South Priuralia Territory. There, according the legends, Amazon women lived, about whom Herodotes, Ptolemy and Pliniy the Elder wrote. It could be also a reason to name the stone. According the legends, martial Amazons cut their left breasts away for better shooting from bows (Gk. “amazon” – without a breast). Many peoples treated amazonite as a sacred stone and used it for amulets.

Orthoclase (Orthoklas—Orthose—Ортоклаз) (Breithaupt, A. 1823), from Gk. “orthos” – right and “klas” – to break, is alluding to its two prominent cleavages at right angles. Composition – (K,Na)[Si,Al)4O8], monoclinic system. Sometimes, hyalloalophane and sanidine, are used as ornamental stones; monoclinic system. In its content, orthoclase is an analogue of microcline, which differs from it only with specifics of its structure because of higher symmetry. All the other properties and conditions of the origin are the same. The most interesting are transparent varieties of noble orthoclase available for faceting: colorless water stone, yellow ferriorthoclase and translucent, opalescent adularia – moonstone. For orthoclase bright iridescence is typical, it depends on the interference of light on the cleavage planes with the presence of submicroscopic perthites and microperthites of albite. Such orthoclase with iridescence in gray tones is called wolf ’s-eye. Sometimes, in jewelry they use green orthoclaselennilite or flesh-red one – erytrite, or leelite. Orthoclase can display aventurescence depending on inclusions of hematite flakes on the cleavage planes. Such golden-rose variety they call orthoclase sunstone.

Adularia (adular) is a translucent to transparent variety of orthoclase typical for alpine veins. Its crystals are orthorhombic in slabs, up to 10 cm. in the length. The effect of moonstone in transparent adularia is formed with the interference of light in microperthite inclusions of albite; it displays itself as pearls shining and chatoyancy during gyration of a processed stone before a source of light. In Western gemology, this effect is called girasol, or adularescence, in Russia – opalescence. The widespread tones of opalescence in adularia are milky-white and light bluish, that’s why it is called adularia fish-eye. In rare cases, the play of color, typical for moonstone, gives the effect of fire. Under specific orientation, moonstone displays alas well asterism. It depends on inclusions of goethite, which give also brown, red-brown, greenish-brown to green and gray hue in red moonstone. Moonstone with light blue opalescence is the most valuable one; after processing it can be up to 20 ct., and with white opalescence – several hundreds of carat.

Ferriorthoclase is a golden-yellow variety of noble orthoclase, it was discovered by the French mineralogist Lacroix on Madagascar in 1913. It is extracted in cavities of orthoclase-microcline pegmatites at the Itrongay deposit, Fianarantsua Prov., in the south-east of the island, to the southwest from the Betroka Settlement Transparent crystals of ferriorthoclase reached 14 cm. long. The biggest of them faceted in brilliant pattern, 75 ct., is exhibited in the Museum of the Madagascar Company in Paris.

Deposits. Orthoclase as well as microcline is found mainly in pegmatites, metasomatic rocks and schists. In less quantities it is found in hydrothermal veins. In Russia, on the Kola Penin., in alkali pegmatites of the Lovozero and Khibiny massifs, they find iris orthoclase, which possesses the effect of moonstone in translucent differences. In the western part of the Kola Penin., near the Zasteid Mt., in the Sal’nye Tundry hey found granulites gneisses – leptites with oval bodied texture. Oval bodies are represented in these rocks as large crystals of transparent orthoclase moonstone.In the Subpolar Urals Mts., findings of adularia moonstone are known at deposits of rock crystal, for in stance, at the Asbestovoye deposit near the Narodnaya Mt. In the Middle Urals, it was discovered in pegmatites of Alabashka and Mokrusha. In the South Urals, transparent crystals of adularia were found in pegmatite of the Ilmeny Mts., along the Cheremshanka River; in the region of Turgoyak Lake – near the village of Selyanina – Selyaninskie mines, and at the Rechnoye deposit. In the Irkutsk Region, moonstone was found at the Slyudyanka deposit; in East Transbaikalia – in pegmatites of the Adun Chilon Ridge. In the south of Yakutia – at the Inagli deposit of chrome-diopside, near the city of Aldan. In the Khabarovsk Region adularia was discovered at the deposits Khakandja and Udacha, the Kondior Ridge. In Tadzhikistan, in pegmatites of the Kukurt deposit, East Pamirs, they found half-transparent adularia with play of color from colorless to light bluish-green tone. In the Southwest Pamirs, moonstone was discovered in veins of pegmatites in the basin of the rivers Tjulpar and Shegembet; also in East Pamirs – Bashgumbez River. In its water-transparent crystals the size of segments with iridescence reaches 15-20 cm2 .

In Norway, at the Stavern (Fredriksværn) deposit, Vestfold, and others they extracted golden-yellow orthoclase – murchisonite with light blue play of color. In Poland, crystals of orthoclase were found at the Strzegom (form. Strigau) deposit. In the eastern part of Czech Rep., at the Teplice deposit, they found orthoclase with light blue iridescence. It is known under the trade name aglaurite. In Switzerland, in alpine veins of the region of St Gotthard, Uri canton; and Tinzen, Graubünden canton, findings of adularia crystals, 25 cm. in size, up to 25 kg., are not rare; they have transparent segments. Similar alpine veins with adularia were found in Austria, in Tyrol, near Zillertal and in the Salzburg. At the Habachtal deposit, Salzburg, crystals of adularia reached 15 kg. In alpine veins transparent crystals hyalopane up to 20 cm. occur at deposits Busovaãa and Zagradski Potok, Bosnia and Herzegovine. In northern Italy, near Trieste, they find reddish moonstone, and in Piedmont, in the region of Baveno, they found crystals of orthoclase up to 20 cm. in cross-section. In pegmatites of the deposits Grotta d’Oggi and San Piero in Campo, Elba Is., they found crystals of orthoclase up to 35 cm., including those of gem quality. In Tanzania, orthoclase moonstone is extracted in the Kondoa area. In the south of Madagascar, in the region of Betroka, crystals of transparent orthoclase reach 9x4x3.5 cm. in size at the Itrongay deposit, Toliara Prov. Bright yellow inclusions of crystals of titanite in orthoclase from Madagascar produce the effect of cat’s-eye in processed stones. In Australia, at the Broken Hill deposit, New South Wales, they find bright green orthoclase in twin-crystals up to 10 cm. long. In South India, they discovered green-golden moonstone in the region of KÇngayam, Tamil Nädu. It displays asterism with a four-radial star and a light, moving strip as in the effect of cat’s-eye. On Sri Lanka, they extract greenish-gray ornamental orthoclase, and at placers there is transparent orthoclase – orthoclase fish-eye. There is also the Mitiyagoda deposit of moonstone, and in gneisses they find oval bodies of transparent orthoclase. In Myanmar (Burma), small deposits of light blue moonstone are known. In yellow-white orthoclase, they observed parallel-oriented cavities partially filled with liquid. In cabochon such orthoclase displays the effect of cat’s-eye . In Japan, at the Tanokamiyama deposit, Shiga Pref., they found transparent crystals of orthoclase up to 10 cm. In the U.S.A., on the Prince of Wales Is., Alaska, in cavities among diopside-garnet skarn, they find crystals of adularia up to 25 cm. long. In Arkansas, findings of adularia are known also at a deposit in the Hot Springs Co.; and in Colorado – at the Mt. Antero deposit, Chaffee Co. In Canada, there are small deposits of light blue moonstone. In Mexico, at the Valenciana deposit, Guanahuato State, they extracted gem-quality adularia under the local trade name valencianite.

Ornamental rocks. In Russia, on the Chukchi Penin., at the gold-silver deposits Karamken and Mnogovershinnoye, they discovered adularia-rhodochrosite rock with inclusions of quartz and native gold and also quartz-adularia rock from veined bodies with stripped-cockade texture. It can be also described as a very beautiful ornamental stone. Iris orthoclase is a rock-forming mineral for coarse-grained feldspar syenite – larvikite. In Kyrgyzstan, such ornamental syenite with separate fragments of orthoclase, 35x14 cm. in size, are known near Ysyk-Köl Lake at the Arsy deposit, in the region of Rybach’ye (now Balykchy). This rock possesses pearl-gray iridescence of orthoclase; it is also known as an ornamental and coating stone under the trade name “labradorite”. Another alkali syenite is nordmarkite from Sweden, which is also an ornamental stone because of iridescence of orthoclase. A list of these ornamental rocks we can supplement with amygdaloidal basalt – variolite with greenish oval bodies of orthoclase.

Synonyms. Orthoclase – Aglaurite, from Gk. “aglaos” – sparkling | Barytorthoclas | Cornite, obs. | Delawarite, after the discovery location near Delaware, Pennsylvania, the U.S.A. | Erytrite, from Gk. “erytros” – red | ~ feldspar: common ~, iron ~, lazur ~, nacre ~, prismatic ~| Felsite, Engl. feldspar | Volcanic glass | Albite granite | Leelite, after J. Lee | Lennilite (lenniite), after the discovery location near Lenny, Connecticut, the U.S.A. | Murchisonite, after the English geologist R.I. Murchison | Napoleonite, after the Fr. Emperor Napoleon Bonaparte | Necronite, from Gk. “necros” – dead | Orthose, obs. | Paradoxit | Light stone – from India and Sri Lanka.

Adularia (adular), after the discovery location in the Adula Mt., the Switzerland Alps – Adularia-albite | Orthorhombic feldspar, after the shape of crystals | Ferriorthoclase, after the content | Jandarakand, Hindu. | Lapis lunaris, syn. – moonstone, lunaris (lunary), Lat. | ~ moonstone: adularia ~, light blue ~, Burmese ~, color ~, Ontario ~, precious ~, rainbow ~ | Ceylon opal | Water opal | Iron orthoclase | Ice spar | Nacreous spar | Pearly spar | Silver stone.

Ornamental rocks: – Larvikite (laurvikite), alkali syenite, after the discovery location near Larvik, in the region of Oslo, Norway | Variolite – amygdaloidal basalt, which was known in the medieval medicine as “lapis variolatus”, or variolous stone, because it was used against smallpox according the similarity principle.

In the U.S.A., moonstone is an official emblem of the Florida State.

Sanidine (Sanidin—Sanidine—Санидин) (Nose, K.W. 1808), from Gk. “sanis” – a tablet, alluding to its typical tabular habit. Composition – (K,Na)[(Si,Al)4O8], a structural analogue of orthoclase, its high-temperature modification. Usually, sanidine is colorless or pale yellow – straw sanidine, also it can be blue – azulicite. It displays the effect of moonstone. Transparent to half-transparent. It is found more rarely, than other potassium feldspars, mainly in volcanic rocks. In trachytes, sanidine forms large inclusions of transparent crystals – glass-like sanidine. In Russia, findings of gem-quality sanidine are known in the Jidinskiy Dist. of Buryatia Rep., on the Bartoi River, at placers, because of destroying of volcanic rocks. In Mongolia, at the Shavaryn Tsaram deposit, in alkali basaltoides they find crystals of transparent sanidine, which display the effect of moonstone after processing. In Europe, sanidine available for processing is known in Norway, by Oslo. In Germany, transparent gem-quality pieces sanidine up to 10 cm. and rarely as crystals at Volkesfeld-Weibern, Effel, Rhineland-Palatinate, was found. In Italy, at Vesuvius, at the Monte Somma deposit, vitreous crystals of sanidine – riacolite are found in coulee. They were also found on the Patelleria Is., to the west from Sicily Is. In North Korea, at the Meisen Gan deposit, near Kan-ch’on, Hamgyong-namdo, they extracted sanidine with the effect of moonstone. In the U.S.A., in pegmatites among rhyolite-porphyries at the Black Rang deposit, New York State, sanidine moonstone is found as crystals up to 50 cm. long, and in Idaho and Oregon it was found as colorless and brown crystals. In Mexico, in the Chihuahua State, at the Pili deposit they extracted sanidine moonstone with light blue opalescence. On the New Guinea Is., Papua-New Guinea, crystals of sanidine, up to 7 cm, are extracted from porphyries.

Synonyms. Glassy feldspar | Mikrotin, from Gk. “mikrotes” – smallness | Riacolite, from Gk. “rias” – lava and “litos” –– a stone | Rauch sanidine | Ice spar.

Hyalophane (Hyalophan—Hyalophane—Гиалофан) (von Waltershausen, W.S. 1855), from Gk. “hyallos” – glass and “phanos” – to seem, because of transparency of crystals. It is a transitional variety to celsian, or barium feldspar. Hyalophane – barium - containing orthoclase. It is found as colorless or pale colored, table-shaped, transparent crystals, which size can reach 25 cm. wide. Available for faceting are transparent and opalescent differences with the effect of moonstone. Hyalophane is found both in magmatic rocks and in metasomatic formations. In Russia, findings of its gem-quality crystals up to 20 cm. are known in phlogopite-calcite veins of the Slyudyanka deposit, Southern Pribaikalia. In Bosnia, at the Zagradski Potok deposit, near Busovaça, in alpine vein they found a crystal of hyalophane 60 cm. wide. In Sweden, transparent crystals of hyalophane at the Jakobsberg manganese deposit, Värmland, were found. In Nepal, at the Ganesh Himal deposit they extracted crystals of hyalophane up to 2 cm. In the U.S.A., such hyalophane was found at the Franklin deposit in New Jersey. In California, they extracted gem-quality barium containing orthoclase with the effect of moonstonecassinite.

Cut Gems. Feldspars are usually processed in cabochons for jewelry insets, and its transparent varieties are faceted. Among the unique work of art, we should mention a necklace and a brooch from moonstone with brilliants by Susanne Balpperonne (France). In this set, more than 70 large cabochons of perfect in purity moonstone were mounted with large brilliants. In the Smiths. Inst., Wash., there is a faceted yellow orthoclase from Madagascar, 249.6 ct.; and a pale green orthoclase cat’s-eye, 104.5 ct., and also a famous faceted orthoclase from Sri Lanka – “White Star”, 22.7 car