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Beryl

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Beryl
Three varieties o beryl: morganite, aquamarine an heliodor
General
CategoryCyclosilicate
Formula
(repeatin unit)
Be3Al2(SiO3)6
Strunz clessification09.CJ.05
Creestal seestemHexagonal
Space groupHexagonal dihexagonal dipyramidal
H-M symbol (6/m 2/m 2/m)
Space group: P 6/mmc
Unit cella = 9.21 Å, c = 9.19 Å; Z = 2
Identification
Formula mass537.50
ColourGreen, blae, yellae, colourless, pink an ithers
Creestal habitPrismatic tae tabular cystals; radial, columnar; granular tae compact massive
TwinninRare
CleavageImperfect on {0001}
FracturConchoidal tae irregular
TenacityBrickle
Mohs scale haurdness7.5–8
SkinkleVitreous tae resinous
StreakWhite
DiaphaneitySkyre tae leamin
Speceefic gravityAverage 2.76
Optical propertiesUniaxial (-)
Refractive indexnω = 1.564–1.595
nε = 1.568–1.602
Birefringenceδ = 0.0040–0.0070
PleochroismWaik tae distinct
Ultraviolet fluorescenceNane (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.

References

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