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In geology, beryl is a meeneral componed o beryllium aluminium cyclosilicate wi the chemical formula Be3Al2(SiO3)6. The hexagonal crystals o beryl mey be vera smaa or range tae several meters in size. Terminated crystals is relatively rare. Pure beryl is colourless, but it is frequently tintit bi impurities; possible colours are green, blae, yellae, reid, an white.

Three varieties o beryl: morganite, aquamarine an heliodor
Category Cyclosilicate
(repeatin unit)
Strunz clessification 09.CJ.05
Creestal seestem Hexagonal
Space group Hexagonal dihexagonal dipyramidal
H-M symbol (6/m 2/m 2/m)
Space group: P 6/mmc
Unit cell a = 9.21 Å, c = 9.19 Å; Z = 2
Formula mass 537.50
Colour Green, blae, yellae, colourless, pink an ithers
Creestal habit Prismatic tae tabular cystals; radial, columnar; granular tae compact massive
Twinnin Rare
Cleavage Imperfect on {0001}
Fractur Conchoidal tae irregular
Tenacity Brickle
Mohs scale haurdness 7.5–8
Skinkle Vitreous tae resinous
Streak White
Diaphaneity Skyre tae leamin
Speceefic 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
Pleochroism Waik tae distinct
Ultraviolet fluorescence Nane (some fractur fillin materials uised tae improve emerald's clarity dae fluoresce, but the stane itsel daes nae)
References [1][2][3]