Beryl

From Wikipedia, the free encyclopedia

It has been suggested that Golden beryl be merged into this article or section. (Discuss)

Beryl
Three varieties of beryl: morganite, aquamarine, and heliodor
General
Category	Silicate Mineral species
Chemical formula	Be3Al2(SiO3)6
Identification
Molecular Weight	537.50 gm
Color	Green, Blue, Yellow, Colorless, Pink & others.
Crystal habit	Massive to well Crystalline
Crystal system	Hexagonal - Dihexagonal Dipyramidal
Cleavage	Imperfect on the [0001]
Fracture	Conchoidal
Mohs Scale hardness	7.5-8
Luster	Vitreous
Optical Properties	Uniaxial (-)
Birefringence	δ = 0.004 - 0.007
Ultraviolet fluorescence	None (some fracture filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not)
Streak	White
Specific gravity	Average 2.76
Diaphaneity	Transparent to opaque
References	[1][2]

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. Beryl exhibits conchoidal fracture, has a hardness of 7.5–8, and a specific gravity of 2.63–2.80. It has a vitreous luster and can be transparent or translucent. Its cleavage is poor basal and its habit is dihexagonal bipyramidal. 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 which referred to a precious blue-green color of sea water stone.^[1] The term was later adopted for the mineral beryl more exclusively.^[2]

Contents 1 Varieties 2 Deposits 3 Applications 4 References 5 See also

[edit] Varieties

Varieties of beryl have been considered gemstones since prehistoric times. Recognized for its beauty, in the Bible, in Ezekiel 1:16, the wheels of God's throne are described as having the appearance of "gleaming beryl."

Colorless beryl is called goshenite, pink beryl is morganite, red beryl is bixbite or "red emerald" or "scarlet emerald," clear bright yellow beryl is "golden beryl," yellow-green beryl is heliodor, green beryl is emerald, blue beryl is aquamarine, and deep blue beryl is maxixe. Red beryl is extremely rare and is not used in jewelry as the crystals it forms are very small; it is mined primarily in Utah. Blue beryl (aquamarine) will not fade in color when exposed to sunlight. Maxixe is a deep blue stone that fades to white when exposed to sunlight or is subjected to heat treatment, though the color returns with irradiation. Other, unnamed shades such as honey yellow are also known.

[edit] Deposits

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 Austria, Germany, and Ireland, as well as Brazil, Colombia, Madagascar (especially morganite), Russia, South Africa, the United States, and Zambia. U.S. beryl locations are in California, Colorado, Idaho, New Hampshire, North Carolina, South Dakota, and Utah.

The most famous source of emeralds in the world is at Muzo and Chivor, Boyacá, Colombia, where they make a unique appearance in limestone. Emeralds are also found in the Transvaal, South Africa; Minas Gerais, Brazil; Zambia, and near Mursinka in the Urals in Russia. In the United States, emeralds are found in North Carolina.

New England's pegmatites have produced some of the largest beryls found, including one massive crystal 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 metres long and 3.5 metres in diameter.^[3]

[edit] Applications

Massive beryl is a primary ore of the metal beryllium.

The druids used beryl for scrying,^{[citation needed]} while the Scottish called them “stones of power”.^{[citation needed]} The earliest crystal balls were made from beryl,^{[citation needed]} later being replaced by rock crystal.^{[citation needed]}

Beryl var. emerald	Beryl var. aquamarine, Brazil	Synthetic beryl made in Tajikistan	Heliodor
Morganite crystal	A 9.76-carat faceted morganite	Emerald with host rock	Beryl var. bixbite

[edit] References

1. ^ ^{a b} http://www.mindat.org/min-819.html Beryl: Beryl mineral information and data, Mindat
2. ^ ^{a b} http://www.webmineral.com/data/Beryl.shtml Webmineral Data
3. ^ G. Cressey and I. F. Mercer, Crystals, London, Natural History Museum, 1999

• Sinkankas, John, 1994, Emerald & Other Beryls, Geoscience Press, ISBN 0-8019-7114-4
• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0-471-80580-7
• Minerals.net
• Mineral Galleries

[edit] See also

• List of minerals