hexagonal Cyclosilicates
Emerald
Formula Be3Al2(SiO3)6:Cr
Crystal Structure
#! Species: Emerald (Beryl)
#! System: Hexagonal (6/mmm)
#! Habit: Elongated hexagonal prism with jardin inclusions
hexagonal[6/mmm]:{10-10}@1.0[inclusion:jardin] + {0001}@0.8 | elongate(c:1.5)
hexagonal
6/mmm
{10-10} {0001}
Quick Facts
Hardness
7.5
Specific Gravity
2.72
Refractive Index
1.577
Optical Character
Uniaxial -
Physical Properties
- Crystal System
- hexagonal
- Hardness (Mohs)
- 7.5
- Specific Gravity
- 2.72
- Cleavage
- Indistinct {0001}
- Fracture
- Conchoidal to uneven
- Lustre
- Vitreous
Optical Properties
- Refractive Index
- 1.577
- Birefringence
- 0.006
- Optical Character
- Uniaxial -
- Dispersion
- 0.014
- Pleochroism
- moderate: Blue-green / Yellow-green (More visible in darker stones; best seen perpendicular to c-axis)
- Fluorescence
- Usually inert; weak red in some Colombian (LWUV)
Characteristics
Colours
GreenBluish-greenYellowish-green
Localities
ColombiaZambiaBrazilEthiopia
Common Inclusions
JardinThree-phaseCrystalsFissures
Known Treatments
OilingResin fillingSurface coating
Crystal Forms
hexagonal_prismpinacoid
Diagnostic Features
Three-phase inclusions (Colombian); jardin; Chelsea filter reaction in Cr-bearing
Synthetics & Simulants
Known synthetic and simulant versions of Emerald
Soudé Emerald (Doublet) composite
Flux-Grown Emerald (Crystal) synthetic
Flux
Hydrothermal Emerald (Crystal) synthetic
Hydrothermal
Lechleitner Emerald (Overgrowth) (Overgrowth Crystal) synthetic
Hydrothermal-overgrowth-on-natural-seed (synthetic Hydrothermal Cr+V-rich Beryl Overgrowth Deposited On Natural Colourless Beryl Seed — Goshenite Or Pale Aquamarine)
Related Minerals
Other minerals in the hexagonal system
