Beryl crystal structure
hexagonal

Beryl

Be3Al2Si6O18

Quick Facts

Hardness
7.5-8
Specific Gravity
2.67-2.78
Refractive Index
1.577-1.583

Crystal Structure

hexagonal[6/mmm]:{10-10}@1.0 + {0001}@1.0
hexagonal
6/mmm
{10-10} {0001}

Physical Properties

Crystal Systemhexagonal
Hardness (Mohs)7.5-8
Specific Gravity2.67-2.78
CleavageImperfect basal (rarely seen)
FractureConchoidal to uneven
LustreVitreous

Optical Properties

Refractive Index1.577-1.583
Birefringence0.005-0.009
PleochroismWeak to distinct (varies by variety)
Dispersion0.014

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hexagonal[6/mmm]:{10-10}@1.0 + {0001}@1.0