The Beauty Beryl

Beryl

• named after the latin word beryllus or greek word beryllos, respectively, which is referred to “precious blue-green color-of-sea water stone”
• the first lenses were made of beryl, as glass could not be made clear enough; this is the origin of the German word for glasses, i.e. “Brille”
• there are important varieties, namely the blue Aquamarine (Fe²⁺ impurities), the Green Emerald (Cr³⁺ impurities), the Golden Beryl (Fe³⁺ impurities), the Pink or Rose Beryl named Morganite (after the financier J.P. Morgan, containing Mn²⁺ impurities), and the Red beryl
• Formula: Al₂Be₃Si₆O₁₈
• Space group: P6/mmc (No. 192)
• Crystal system: hexagonal
• Crystal class: 6/mmm
• Lattice parameters: a = b =  9.219 Å, c = 9.198 Å, α = β = 90°, γ =  120°

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Picture: Aquamarine, Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Picture: Emerald, Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Picture: Golden Beryl, Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Picture: Morganit, Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Picture: Red Beryl, Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Crystal structure (click on the picture to download the VESTA file):

(K. Momma and F. Izumi, “VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data,” J. Appl. Crystallogr., 44, 1272-1276 (2011).)

• yellow: SiO₄ tetrahedra, six tetrahedra are corner-connected to form a ring
• green: distorted BeO₄ tetrahedra
• blue: slightly distorted AlO₆ octahedra

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