Crystal structure of beryl
|Color||Green, Blue, Yellow, Colorless, Pink & others.|
|Crystal habit||Massive to well Crystalline|
|Crystal system||Hexagonal (6/m 2/m 2/m) Space Group: P 6/mсc|
|Cleavage||Imperfect on the |
|Mohs scale hardness||7.5–8|
|Diaphaneity||Transparent to opaque|
|Specific gravity||Average 2.76|
|Optical properties||Uniaxial (-)|
|Refractive index||nω = 1.564–1.595,
nε = 1.568–1.602
|Birefringence||δ = 0.0040–0.0070|
|Ultraviolet fluorescence||None (some fracture filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not)|
The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, red, and white. The name comes from the Greek beryllos (βήρυλλος) which referred to a precious blue-green color-of-sea-water stone. The term was later adopted for the mineral beryl more exclusively.
Beryl of various colors is found most commonly in granitic pegmatites, but also occurs in mica schists in the Ural Mountains, and limestone in Colombia. Beryl is often associated with tin and tungsten ore bodies. Beryl is found in Europe in Norway, Austria, Germany, Sweden (especially morganite), and Ireland, as well as Brazil, Colombia, Madagascar, Russia, South Africa, the United States, and Zambia. U.S. beryl locations are in California, Colorado, Idaho, Maine, Connecticut, New Hampshire, North Carolina, South Dakota, and Utah.
New England's pegmatites have produced some of the largest beryls found, including one massive crystal from the Bumpus Quarry in Albany, Maine with dimensions 5.5 m by 1.2 m (18 ft by 4 ft) with a mass of around 18 metric tons; it is New Hampshire's state mineral. As of 1999, the largest known crystal of any mineral in the world is a crystal of beryl from Madagascar, 18 meters long and 3.5 meters in diameter.
Varieties of beryl have been considered gemstones since prehistoric times:
Aquamarine (from Lat. aqua marina, "water of the sea") is a blue or turquoise variety of beryl. It occurs at most localities which yield ordinary beryl, some of the finest coming from Russia. The gem-gravel placer deposits of Sri Lanka contain aquamarine. Clear yellow beryl, such as occurs in Brazil, is sometimes called aquamarine chrysolite. When corundum presents the bluish tint of typical aquamarine, it is often termed Oriental aquamarine. The deep blue version of aquamarine is called maxixe. Its color fades to white when exposed to sunlight or is subjected to heat treatment, though the color returns with irradiation.
The pale blue color of aquamarine is attributed to Fe2+. The Fe3+ ions produce golden-yellow color, and when both Fe2+ and Fe3+ are present, the color is a darker blue as in maxixe. Decoloration of maxixe by light or heat thus may be due to the charge transfer Fe3+ and Fe2+. Dark-blue maxixe color can be produced in green, pink or yellow beryl by irradiating it with high-energy particles (gamma rays, neutrons or even X-rays).
In the United States, aquamarines can be found at the summit of Mt. Antero in the Sawatch Range in central Colorado. In Wyoming, aquamarine has been discovered in the Big Horn mountains, near Powder River Pass. In Brazil, there are mines in the states of Minas Gerais, Espírito Santo and Bahia. The Mines of Colombia, Zambia, Madagascar, Malawi, Tanzania and Kenya also produce aquamarine.
The biggest aquamarine ever mined was found at the city of Marambaia, Minas Gerais, Brazil, in 1910. It weighed over 110 kg, and its dimensions were 48.5 cm long and 42 cm in diameter.
Red beryl (also known as "bixbite", "red emerald", or "scarlet emerald") is a red variety of beryl. It was first described in 1904 for an occurrence, its type locality, at Maynard's Claim (Pismire Knolls), Thomas Range, Juab County, Utah, USA. The old synonym bixbite is deprecated from the CIBJO, because of the risk of confusion with the mineral bixbyite (also named after the mineralogist Maynard Bixby). The dark red color of bixbite is attributed to Mn3+ ions.
Red beryl is rare and has only been reported from a handful of locations including: Wah Wah Mountains, Beaver County, Utah; Paramount Canyon, Sierra County, New Mexico; Round Mountain, Sierra County, New Mexico; and Juab County, Utah. The greatest concentration of gem-grade red beryl comes from the Violet Claim in the Wah Wah Mountains of mid-western Utah, discovered in 1958 by Lamar Hodges, of Fillmore, Utah, while he was prospecting for uranium.
While gem beryls are ordinarily found in pegmatites and certain metamorphic rocks, bixbite occurs in topaz-bearing rhyolites. It formed by crystallizing under low pressure and high temperature from a pneumatolitic phase along fractures or within near-surface miarolitic cavities of the rhyolite. Associated minerals include bixbyite, quartz, orthoclase, topaz, spessartine, pseudobrookite and hematite. The red color is thought to be from manganese substituting for aluminium in the beryl structure.
Emerald refers to green beryl, colored by trace amounts of chromium and sometimes vanadium. The word "emerald" comes from Latin smaragdus from Greek smaragdos - σμάραγδος, its original source being a Semitic word izmargad or the Sanskrit word, marakata (मरकन), meaning "green". Most emeralds are highly included, so their brittleness (resistance to breakage) is classified as generally poor.
Emeralds in antiquity were mined by the Egyptians and in Austria, as well as Swat in northern Pakistan. A rare type of emerald known as a trapiche emerald is occasionally found in the mines of Colombia. A trapiche emerald exhibits a "star" pattern; it has raylike spokes of dark carbon impurities that give the emerald a six-pointed radial pattern. It is named for the trapiche, a grinding wheel used to process sugarcane in the region. Colombian emeralds are generally the most prized due to their transparency and fire. Some of the most rare emeralds come from three main emerald mining areas in Colombia: Muzo, Coscuez, and Chivor. Fine emeralds are also found in other countries, such as Zambia, Brazil, Zimbabwe, Madagascar, Pakistan, India, Afghanistan and Russia. In the US, emeralds can be found in Hiddenite, North Carolina. In 1998, emeralds were discovered in the Yukon.
Emerald is a rare and valuable gemstone and, as such, it has provided the incentive for developing synthetic emeralds. Both hydrothermal and flux-growth synthetics have been produced. The first commercially successful emerald synthesis process was that of Carroll Chatham. The other large producer of flux emeralds was Pierre Gilson Sr., which has been on the market since 1964. Gilson's emeralds are usually grown on natural colorless beryl seeds which become coated on both sides. Growth occurs at the rate of 1 mm per month, a typical seven-month growth run producing emerald crystals of 7 mm of thickness. The green color of emeralds is attributed to presence of Fe3+ and Fe2+ ions. 
Golden beryl can range in colors from pale yellow to a brilliant gold. Unlike emerald, golden beryl has very few flaws. The term "golden beryl" is sometimes synonymous with heliodor (from Greek hēlios - ἥλιος "sun" + dōron - δῶρον "gift") but golden beryl refers to pure yellow or golden yellow shades, while heliodor refers to the greenish-yellow shades. The golden yellow color is attributed to Fe3+ ions. Both golden beryl and heliodor are used as gems. Probably the largest cut golden beryl is the flawless 2054 carat stone on display in the Hall of Gems, Washington, D.C.
Colorless beryl is called goshenite. The name originates from Goshen, Massachusetts where it was originally described. Since all these color varieties are caused by impurities and pure beryl is colorless, it might be tempting to assume that goshenite is the purest variety of beryl. However, there are several elements that can act as inhibitors to color in beryl and so this assumption may not always be true. The name goshenite has been said to be on its way to extinction and yet it is still commonly used in the gemstone markets. Goshenite is found to some extent in almost all beryl localities. In the past, goshenite was used for manufacturing eyeglasses and lenses owing to its transparency. Nowadays, it is most commonly used for gemstone purposes and also considered as a source of beryllium.
The gem value of goshenite is relatively low. However, goshenite can be colored yellow, green, pink, blue and in intermediate colors by irradiating it with high-energy particles. The resulting color depends on the content of Ca, Sc, Ti, V, Fe, and Co inmpurities.
Morganite, also known as "pink beryl," "rose beryl," "pink emerald," and "cesian beryl," is a rare light pink to rose-colored gem-quality variety of beryl. Orange/yellow varieties of morganite can also be found, and color banding is common. It can be routinely heat treated to remove patches of yellow and is occasionally treated by irradiation to improve its color. The pink color of morganite is attributed to Mn2+ ions.
Pink beryl of fine color and good sizes was first discovered on an island on the coast of Madagascar in 1910. It was also known, with other gemstone minerals, such as tourmaline and kunzite, at Pala, California. In December 1910,the New York Academy of Sciences named the pink variety of beryl "morganite" after financier J. P. Morgan.
On October 7, 1989, one of the largest gem morganite specimens ever uncovered, eventually called "The Rose of Maine," was found at the Bennett Quarry in Buckfield, Maine. The crystal, originally somewhat orange in hue, was 23 cm long and about 30 cm across, and weighed (along with its matrix) just over 50 lbs (23 kg).
BERYL, a mineral containing beryllium and aluminium in the form of a silicate; its formula is Bea Ale Si b 0 18. The species includes the emerald, the aquamarine and other transparent varieties known as "precious beryl," with certain coarse varieties unfit for use as gem-stones. The name comes from the Gr. 1 6r t pvAA03, a word of uncertain etymology applied to the beryl and probably several other gems. It is notable that the relation of the emerald to the beryl, though proved only by chemical analysis, was conjectured at least as far back as the time of Pliny.
Beryl crystallizes in the hexagonal system, usually taking the form of long six-sided prisms, striated vertically and terminated with the basal plane, sometimes associated with various pyramidal faces (see fig.). It cleaves rather imperfectly parallel to the base. The colour of beryl may be blue, green, yellow, brown or rarely pink; while in some cases the mineral is colourless. The specific gravity is about 2.7, and the hardness 7.5 to 8, so that for a gem-stone beryl is comparatively soft. Whilst the gemvarieties are transparent, the coarse beryl may be opaque. The transparent crystals are pleochroic - a character well marked in emerald.
Beryl was much prized as a gem-stone by the ancients, and Greek intaglios of very fine workmanship are extant. The Roman jewellers, taking advantage of the columnar form of the natural crystal, worked it into long cylinders for ear-pendants. It was a favourite stone with the artists of the Renaissance, but in modern times has lost popularity, except in the form of emerald, which remains one of the most valued gem-stones. It is notable that English lapidaries of the 18th century often included the sard under the term beryl - a practice which has led to some confusion in the nomenclature of engraved gems.
Beryl occurs as an accessory constituent of many granitic rocks, especially in veins of pegmatite, whilst it is found also in. gneiss and in mica-schist. Rolled pebbles of beryl occur, with topaz, in Brazil, especially in the province of Minas Geraes. Crystals are found in drusy cavities in granite in the Urals, notably near Mursinka; in the Altai Mountains, which have yielded very long prismatic crystals; and in the mining district of Nerchinsk in Siberia, principally in the Adun-Chalon range, where beryl occurs in veins of topaz-rock piercing granite. Among European localities may be mentioned Elba, good crystals being occasionally found in the tourmaline-granite of San Piero. In Ireland excellent crystals of beryl occur in druses of the granite of the Mourne Mountains in Co. Down, and others less fine are found in the highlands of Donegal, whilst the mineral is also known from the Leinster granite. It occurs likewise in the granite of the Grampians in Scotland, and is not unknown in Cornwall, specimens having been found, with topaz, apatite, &c., in joints of the granite of St Michael's Mount.
Many localities in the United States yield beryl, sometimes sufficiently fine to be cut as a gem. It is found, for example, at Hiddenite and elsewhere in Alexander county, N.C.; at Haddam and Monroe, Conn.; at Stoneham and at Albany, in Oxford county, Maine; at Royalston, Mass.; and at Mt. Antero, Colorado, where it occurs with phenacite. Beryl of beautiful pink colour occurs in San Diego county, California. Coarse beryl, much rifted, is found in crystals of very large size at Grafton and Acworth, N.H.; a crystal from Grafton weighing more than 22 tons. A colourless beryl from Goshen, Mass., has been called Goshenite; whilst crystals of coarse yellow beryl from Rubislaw quarry in Aberdeenshire, Scotland, have been termed Davidsonite.
the rendering in the Authorized Version of the Hebrew word tarshish, a precious stone; probably so called as being brought from Tarshish. It was one of the stones on the breastplate of the high priest (Ex 28:20; R.V. marg., "chalcedony;" 39:13). The colour of the wheels in Ezekiel's vision was as the colour of a beryl stone (1:16; 10:9; R.V., "stone of Tarshish"). It is mentioned in Song 5:14; Dan 10:6; Rev 21:20. In Ezek 28:13 the LXX. render the word by "chrysolite," which the Jewish historian Josephus regards as its proper translation. This also is the rendering given in the Authorized Version in the margin. That was a gold-coloured gem, the topaz of ancient authors.
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Beryl is a silicate mineral, and is the main ore of beryllium metal. It is sometimes found as very, very large crystals, as much as 18 m. (59 ft.) long. Colored clear beryl is often used for jewelry, including emerald (green), aquamarine (bluegreen), bixbite (red), morganite (pink), and heliodor (golden).
Aigue-marine sur mica (Pakistan).jpg