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, a specific gravity of 2.63-2.80. It has a vitreous lustre 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 for the precious blue-green color of sea water.
Varieties of beryl have been considered gemstones since prehistoric times. Green beryl is called emerald, red beryl is bixbite or red emerald or scarlet emerald, blue beryl is aquamarine, pink beryl is morganite, and a clear bright yellow beryl is called golden beryl. Other shades such as yellow-green for heliodor and honey yellow are common.
Beryl is found most commonly in granitic pegmatites, but also occurs in mica schists in the Ural Mountains and is often associated with tin and tungsten orebodies. Beryl is found in Europe in Austria, Germany, and Ireland. Beryl occurs in Madagascar (especially morganite).
The most famous source of emeralds in the world is at Muso and Chivor, Colombia, where they make a unique appearance in limestone. Emeralds are also found in the Transvaal, South Africa, Minas Gerais, Brazil, and near Mursinka in Urals. 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. Other beryl locations include South Dakota, Colorado, Utah, and California.
Massive beryl is a primary ore of the metal beryllium.