hexagonal Cyclosilicates
Aquamarine
Formula Be3Al2(SiO3)6:Fe
Crystal Structure
#! Species: Aquamarine (Beryl)
#! System: Hexagonal (6/mmm)
#! Habit: Elongated hexagonal prism
hexagonal[6/mmm]:{10-10}@1.0 + {0001}@0.5 | elongate(c:2.5)
hexagonal
6/mmm
{10-10} {0001}
Quick Facts
Hardness
7.5
Specific Gravity
2.67
Refractive Index
1.577
Optical Character
Uniaxial -
Physical Properties
- Crystal System
- hexagonal
- Hardness (Mohs)
- 7.5
- Specific Gravity
- 2.67
- Cleavage
- Imperfect basal (rarely seen)
- Fracture
- Conchoidal to uneven
- Lustre
- Vitreous
Optical Properties
- Refractive Index
- 1.577
- Birefringence
- 0.006
- Optical Character
- Uniaxial -
- Dispersion
- 0.014
- Pleochroism
- weak: Near colorless / Pale blue (Often not visible; best seen in well-saturated stones)
Characteristics
Colours
BlueBlue-greenGreenish-blueSanta Maria blue (medium-dark saturated)
Localities
BrazilPakistanMadagascarMozambiqueNigeria
Common Inclusions
Rain (parallel tubes)Two-phase inclusionsCrystal inclusions
Known Treatments
Heat treatment (to reduce green and enhance blue)
Crystal Forms
hexagonal_prismpinacoid
Related Minerals
Other minerals in the hexagonal system
