View source for Beryl

{{Infobox mineral
| name        = Beryl
| category    = [[Silicate mineral]]s, cyclosilicate subclass, 6-membered single ring series
| boxwidth    =
| boxbgcolor  =
| image       = Beryl.GIF
| imagesize   =
| caption     = Crystal structure of beryl
| strunz      = 09.CJ.05
| dana        = 61.01.01.01
| formula     = Be<sub>3</sub>Al<sub>2</sub>(<nowiki>SiO</nowiki><sub>3</sub>)<sub>6</sub>
| molweight   = 537.50 g/mol
| color       = colorless when pure, but ''see text''
| habit       = massive to well crystallized
| system      = [[Hexagonal crystal system|hexagonal]]
| symmetry    = 6/m 2/m 2/m
| twinning    =
| cleavage    = Imperfect on the [0001]
| fracture    = [[Conchoidal]]
| tenacity    =
| mohs        = 7.5-8
| luster      = vitreous
| polish      =
| opticalprop = Uniaxial (-)
| refractive  = n<sub>ω</sub> = 1.564-1.595,<br> n<sub>ε</sub> = 1.568-1.602
| birefringence = δ = 0.0040-0.0070
| dispersion  =
| pleochroism =
| fluorescence= None (some fracture filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not)
| absorption  =
| streak      = White
| gravity     = Average 2.76
| density     =
| melt        =
| fusibility  =
| diagnostic  =
| solubility  =
| diaphaneity = Transparent to opaque
| other       =
| references  = <ref name="Webmineral">{{WebMineral-ref | name = Beryl | url = http://www.webmineral.com/data/Beryl.shtml | accessdate = 2009-12-04}}.</ref><ref name="Mindat">{{MinDat-ref | name = Beryl| id = 819 | accessdate = 2009-12-04}}.</ref><ref>{{citation | last1 = Brown | first1 = G. E. | last2 = Mills | first2 = B. A. | year = 1986 | title = High-temperature structure and crystal chemistry of hydrous alkali-rich beryl, from the Harding pegmatite, Taos County, New Mexico | journal = American Mineralogist | volume = 71 | pages =547–56}}.</ref>
}}
The [[mineral]] '''beryl''' is a [[beryllium]] [[aluminium]] [[Silicate minerals#Cyclosilicates|cyclosilicate]] with the [[chemical formula]] Be<sub>3</sub>Al<sub>2</sub>(<nowiki>SiO</nowiki><sub>3</sub>)<sub>6</sub>. The [[hexagonal]] [[crystal]]s 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 language|Greek]] ''beryllos'' which referred to a ''precious blue-green color-of-sea-water'' stone.<ref name="Mindat"/> The term was later adopted for the mineral beryl more exclusively.<ref name="Webmineral"/>

==Deposits==
[[File:Beryl09.jpg|thumb|left|Three varieties of beryl: morganite, aquamarine and heliodor]]
Beryl of various  colors is found most commonly in [[granite|granitic]] [[pegmatite]]s, but also occurs in [[mica]] [[schist]]s in the [[Urals|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 [[Republic of Ireland|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&nbsp;ft by 4&nbsp;ft) with a mass of around 18 [[Tonne|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.<ref>{{citation | first1 = G. | last1 = Cressey | first2 = I. F. | last2 = Mercer | title = Crystals | location = London | publisher = Natural History Museum | year = 1999}}.</ref>

==Varieties==
Varieties of beryl have been considered [[gemstone]]s since prehistoric times: 

===Aquamarine and maxixe===
[[File:AguamarinhaEZ.jpg|left|100px]]
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 mining|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 Fe<sup>2+</sup>. The Fe<sup>3+</sup> ions produce golden-yellow color, and when both Fe<sup>2+</sup> and Fe<sup>3+</sup> 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 Fe<sup>3+</sup> and Fe<sup>2+</sup>.<ref name=color>{{citation | url = http://minerals.caltech.edu/FILES/Visible/BERYL/Index.htm | title = Color in the Beryl group | accessdate = 2009-06-06}}.</ref><ref name=ibragim>{{citation | last1 = Ibragimova | first1 = E. M. | last2 = Mukhamedshina | first2 = N. M.| last3 = Islamov | first3 = A. Kh. | year = 2009 | title = Correlations between admixtures and color centers created upon irradiation of natural beryl crystals | journal = Inorg. Mat. | volume = 45 | issue = 2 | pages = 162–67 | doi = 10.1134/S0020168509020101}}</ref><ref name=viana1>{{citation | last1 = Viana | first1 = R. R. | last2 = Da Costa | first2 = G. M.| last3 = De Grave | first3 = E. | last4 = Stern | first4 = W. B. | last5 = Jordt-Evangelista | first5 = H. | year = 2002 | title = Characterization of beryl (aquamarine variety) by Mössbauer spectroscopy | journal = Phys. Chem. Minerals | volume = 29 | issue = 1 | pages = 78–86 | doi = 10.1007/s002690100210}}.</ref><ref name=blak>{{citation | last1 = Blak | first1 = Ana Regina | last2 = Isotani | first2 = Sadao | last3 = Watanabe | first3 = Shigueo | year = 1983 | title = Optical absorption and electron spin resonance in blue and green natural beryl: A reply | journal = Phys. Chem. Minerals | volume = 9 | issue = 6 | pages = 279–80 | doi = 10.1007/BF00309581}}.</ref> Dark-blue maxixe color can be produced in green, pink or yellow beryl by irradiating it with high-energy particles ([[gamma ray]]s, [[neutron]]s or even [[X-ray]]s).<ref>{{citation | first1 = Kurt | last1 = Nassau | first2 = Betty E. | last2 = Prescott | first3 = D. L. | last3 = Wood | title = The deep blue Maxixe-type color center in beryl | url = http://www.minsocam.org/ammin/AM61/AM61_100.pdf | journal = American Mineralogist | volume = 61 | year = 1976 | page = 100–7}}.</ref>
 
In the [[United States]], aquamarines can be found at the summit of [[Mount Antero|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&nbsp;kg, and its dimensions were 48.5&nbsp;cm long and 42&nbsp;cm in diameter.

===Bixbite===
[[File:Bixbite.gif|100px|left]]
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 (geology)|type locality]], at Maynard's Claim (Pismire Knolls), Thomas Range, [[Juab County, Utah|Juab County]], Utah, USA.<ref>{{MinDat-ref | name = Red Beryl | id = 690 | accessdate = 2009-12-04}}.</ref><ref>{{citation | first = Carl | last = Ege | title = What gemstone is found in Utah that is rarer than diamond and more valuable than gold? | url = http://geology.utah.gov/surveynotes/gladasked/gladberyl.htm | publisher = Utah Geological Survey | accessdate = 2009-12-04}}.</ref> 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 Mn<sup>3+</sup> ions.<ref name=color/>

Red beryl is rare and has only been reported from a handful of locations including: [[Wah Wah Mountains]], [[Beaver County, Utah]]; [[Black Range|Paramount Canyon]], [[Sierra County, New Mexico]]; [[Black Range|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]].<ref>{{citation | title = Red Emerald History | url = http://www.redemerald.com/history.html | date = 2007-11-21 | accessdate = 2007-11-21}}.</ref>

While gem beryls are ordinarily found in pegmatites and certain metamorphic rocks, bixbite occurs in [[topaz]]-bearing [[rhyolite]]s. 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===
{{Main|Emerald}}
[[File:Émeraude (Colombie).jpg|100px|left]]
[[File:National Museum of Natural History Emeralds 2.JPG|220px|right|thumb|Rough and faceted emeralds from the collection at the [[National Museum of Natural History]]]]
Emerald refers to green beryl, colored by trace amounts of [[chromium]] and sometimes [[vanadium]].<ref name=color/><ref name=Hurlbut>{{citation | last1 = Hurlbut | first1 = Cornelius S., Jr. | last2 = Kammerling | first2 = Robert C. | year = 1991 | title = Gemology | page = 203 | publisher = Wiley | location = New York}}.</ref> The word "emerald" comes from [[Latin]] ''smaragdus'' from [[Ancient Greek|Greek]] ''smaragdos - σμάραγδος'', its original source being a [[Semitic]] word ''izmargad'' or the [[Sanskrit]] word, ''marakata'', meaning "green".<ref name=Fernie>{{citation | last = Fernie | first = W. T. | year = 1906 | title = Precious Stones for Curative Wear | publisher = John Wright}}.</ref> Most emeralds are highly [[inclusion (mineral)|included]], so their brittleness (resistance to breakage) is classified as generally poor. 

Emeralds in antiquity were mined by the [[Ancient Egypt|Egyptians]] and in [[Austria]], as well as [[Swat (Pakistan)|Swat]] in northern [[Pakistan]].<ref>{{citation | last1 = Giuliani | first1 = Gaston | last2 = Chaussidon | first2 = Marc | last3 = Schubnel | first3 = Henri-Jean | last4 = Piat | first4 = Daniel H. | last5 = Rollion-Bard | first5 = Claire | last6 = France-Lanord | first6 = Christian | last7 = Giard | first7 = Didier | last8 = De Narvaez | first8 = Daniel | last9 = Rondeau | first9 = Benjamin | year = 2000 | title = Oxygen Isotopes and Emerald Trade Routes Since Antiquity | journal = Science | volume = 287 | pages = 631–33 | doi = 10.1126/science.287.5453.631}}.</ref> 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 [[Asterism (gemmology)|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<ref>{{citation | last = Hosaka | first = M. | year = 1991 | title =Hydrothermal growth of gem stones and their characterization | journal = Progr. Cryst. Growth Charact. Mat. | volume = 21 | pages = 71–96 | doi = 10.1016/0960-8974(91)90008-Z}}.</ref> 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&nbsp;mm per month, a typical seven-month growth run producing emerald crystals of 7&nbsp;mm of thickness.<ref>{{citation | last = Nassau | first = K. | year = 1980 | title = Gems Made By Man | publisher = Gemological Institute of America | isbn = 0873110161}}.</ref> The green color of emeralds is attributed to presence of Fe<sup>3+</sup> and Fe<sup>2+</sup> ions.<ref name=ibragim/>
<ref name=viana1/><ref name=blak/>

===Golden beryl and heliodor===
[[File:Pierre-img 0591.jpg|100px|thumb|Golden beryl]]
[[File:Beryl heliodor polished XH.jpg|thumb|90px|left|Heliodor]]
''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 Fe<sup>3+</sup> ions.<ref name=color/><ref name=ibragim/> Both golden beryl and heliodor are used as gems. Probably the largest cut golden beryl is the flawless 2054 [[Carat (mass)|carat]] stone on display in the [[National_Museum_of_Natural_History#Hall_of_Geology.2C_Gems.2C_and_Minerals|Hall of Gems]], [[Washington, D.C.]]<ref>{{citation | first = Arthur | last = Thomas | year=2007 | title = Gemstones | url = http://books.google.com/books?id=MPZK8ILOSR0C | publisher = New Holland Publishers| isbn = 1845376021 | page=77}}.</ref>
{{clear}}

===Goshenite===
[[File:Zrost beryli, Namibia3.jpg|100px|left]]
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.<ref>{{citation | url = http://www.galleries.com/minerals/gemstone/goshenit/goshenit.htm | title = Goshenite, the colorless variety of beryl | accessdate = 2009-06-06}}.</ref><ref>{{citation | url = http://opticalmineralogy.com/the-silicates-mineral-class/goshenite-gem/ | title = Goshenite gem | accessdate = 2009-06-06}}.</ref>

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 resoluting color depends on the content of Ca, Sc, Ti, V, Fe, and Co inmpurities.<ref name=ibragim/>
{{clear}}

===Morganite===
[[File:Morganite (Brésil).jpg|100px|left]]
Morganite, also known as "pink beryl," "rose beryl," "pink emerald," and "cesian beryl," is a rare light pink to rose-colored [[Gemstone|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 Mn<sup>2+</sup> ions.<ref name=color/>
 
==== Discovery and naming ====
Morganite was first discovered together with other gemstone minerals, such as [[tourmaline]] and [[kunzite]], at [[Pala, California]], early in the twentieth century. This started a bonanza for these quite popular gemstones which drew the attention of gemologist [[George Frederick Kunz]], who knew that pink beryl was quite a rarity.<ref>{{citation | url = http://www.addmorecolortoyourlife.com/gemstones/morganite.asp | title = Morganite discovery in Pala, CA | publisher = AGTA | accessdate = 2007-02-20}}.</ref> In 1911, Kunz suggested naming the pink variety of beryl "morganite" after financier [[J. P. Morgan]].<ref>{{citation | url = http://www.gemstone.org/gem-by-gem/english/morganite.html | title = Morganite | publisher = International Colored Gemstone Association | accessdate = 2007-01-22}}.</ref>

==== The Rose of Maine ====
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]].<ref>{{citation | url = http://findarticles.com/p/articles/mi_qa3672/is_/ai_n8728364 | title = Mineralogy of the Bennett pegmatite, Oxford County, Maine}}.</ref>  The crystal, originally somewhat orange in hue, was 23&nbsp;cm long and about 30&nbsp;cm across, and weighed (along with its matrix) just over 50&nbsp;lbs (23&nbsp;kg).<ref>{{citation | url = http://maine.gov/doc/nrimc/mgs/explore/minerals/guide/chapter5/bennett-3.htm | title = The Rose of Maine}}.</ref>

==References==
{{commons|Category:Beryl}}
{{reflist}}

===Further reading===
* {{citation | last1 = Hurlbut | first1 = Cornelius S. | last2 = Klein | first2 = Cornelis | year = 1985 | title = Manual of Mineralogy | edition = 20th | publisher = Wiley | location = New York | isbn = 0-471-80580-7}}.
* {{citation | last = Sinkankas | first = John | year = 1994 | title = Emerald & Other Beryls | publisher = Geoscience Press | isbn = 0-8019-7114-4}}.

==External links==
* [http://www.minerals.net/mineral/silicate/cyclo/beryl/beryl.htm Minerals.net]
* [http://mineral.galleries.com/minerals/silicate/beryl/beryl.htm Mineral Galleries]

[[Category:Beryllium minerals]]
[[Category:Aluminium minerals]]
[[Category:Cyclosilicates]]

{{Imported from Wikipedia|name=Beryl|id=329413729}}