Silicates · Sourced PROFILE
Beryl
Be₃Al₂Si₆O₁₈
A ring silicate mineral family that includes emerald and aquamarine.
AT A GLANCE
- Formula
- Be₃Al₂Si₆O₁₈
- Crystal system
- Hexagonal
- Space group
- P6/mcc
- Mohs hardness
- 7.5
- Density
- 2.63–2.97 g/cm³
- Optical character
- Uniaxial (−)
CRYSTALLOGRAPHY
Crystal form & structure
Usually hexagonal prisms, sometimes tabular; crystals may be vertically striated, etched, or exceptionally large in pegmatites.
HAND-SAMPLE PROPERTIES
Physical properties
- Cleavage
- Imperfect basal cleavage
- Fracture
- Conchoidal to uneven
- Tenacity
- Brittle
- Streak
- White
- Luster
- Vitreous to resinous
- Transparency
- Transparent to translucent
- Observed colours
- Colourless, green, blue, yellow, pink, red, or white
LIGHT & OPTICS
Optical properties
- Optical class
- Uniaxial (−)
- Refractive index
- nω about 1.568–1.602; nε about 1.564–1.595
- Fluorescence & electrical behaviour
- Usually weak or inert; response varies with colour centres and impurities.
GEOLOGICAL SETTING
Formation
Commonly crystallizes in granitic pegmatites and some metamorphic environments.
MINERAL COMPANY
Common associations
Quartz, feldspars, muscovite, lepidolite, spodumene, tourmaline, topaz, and cassiterite
FIELD NOTES
How to identify it
Recognise hexagonal prisms, hardness 7.5–8, relatively low density, and imperfect basal cleavage. Emerald and aquamarine are coloured beryl, sharing the same ring-silicate framework.
NAME & HISTORY
Where the name comes from
From ancient Greek beryllos, a name for precious blue-green stones.
SCIENTIFIC SOURCE
Handbook of Mineralogy — Beryl
External reference; factual profile paraphrased and attributed. Copyright remains with the publisher.
PROVENANCE
Documented occurrences
Kukurt pegmatite field, Eastern Pamir · Beryl is documented as a common accessory mineral in the Dorozhny miarolitic granitic pegmatite. The public record remains at regional precision and is not collecting guidance.
Sourced · Region precisionBadakhshanite-(Y), a new mineral species from a granite miarolitic pegmatite in Eastern Pamir (Pautov et al., 2020)