hexagonal Cyclosilicates
Aquamarine
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 -
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Open in PlaygroundPhysical Properties
Crystal Systemhexagonal
Hardness (Mohs)7.5
Specific Gravity2.67
CleavageImperfect basal (rarely seen)
FractureConchoidal to uneven
LustreVitreous
Optical Properties
Refractive Index1.577
Birefringence0.006
Optical CharacterUniaxial -
Dispersion0.014
Pleochroismweak: Near colorless / Pale blue (Often not visible; best seen in well-saturated stones)
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
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Open in PlaygroundRelated Minerals
Other minerals in the hexagonal system
