Search..
![answer answer](https://duckduckgo.com/i/bd7a99e4.jpg)
Beryl
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... Wikipedia
- Category: Cyclosilicate
- Strunz classification: 9.CJ.05
- Crystal system: Hexagonal
- Crystal class: Dihexagonal dipyramidal (6/mmm), H-M symbol: (6/m 2/m 2/m)
- Space group: P6/mcc
- Unit cell: a
- Formula mass: 537.50 g/mol
- Color: Green, blue, yellow, colorless, pink, and others
- Crystal habit: Prismatic to tabular crystals, radial, columnar, granular to compact massive
- Twinning: Rare
- Cleavage: Imperfect on
- Fracture: Conchoidal to irregular
- Tenacity: Brittle
- Mohs scale hardness: 7.5–8.0
- Luster: Vitreous to resinous
- Streak: White
- Diaphaneity: Transparent to translucent
- Specific gravity: 2.63–2.92
- Optical properties: Uniaxial (−)
- Refractive index: n ω
- Birefringence: δ
- Pleochroism: Weak to distinct
- Ultraviolet fluorescence: None (some fracture-filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not). Morganite has weak violet fluorescence.
- Data Source: DuckDuckGo