Beryl
Gemstone
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Beryl is a mineral composed of beryllium aluminium silicate with the chemical formula Be₃Al₂Si₆O₁₈. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring hexagonal crystals of beryl can be up to several meters in size,... Wikipedia
Chemical formula: Be₃Al₂SiO₆
Hardness (Mohs hardness scale): 7.5 – 8
Refractive index: 1.57 – 1.58
Cleavage: Imperfect on
Crystal habit: Prismatic to tabular crystals; radial, columnar; granular to compact massive
Crystal system: Hexagonal