Beryl | |
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![]() Three varieties o beryl: morganite, aquamarine an heliodor | |
General | |
Category | Cyclosilicate |
Formula (repeatin unit) | Be3Al2(SiO3)6 |
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 |
Identification | |
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] |
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.