Beryl
Beryl | |
---|---|
Chemical composition | Be3Al2(SiO3)6 Beryllium aluminum silicate |
Crystal system | Hexagonal |
Habit | Prismatic |
Cleavage | Very difficult in one direction, rarely seen |
Fracture | Conchoidal |
Hardness | 7.25-7.75 |
Optic nature | Uniaxial - |
Refractive index | 1.577-1.583 (+ or - 0.017) |
Birefringence | 0.005-0.009 |
Dispersion | Low, 0.014 |
Specific gravity | 2.72 (+0.18,- 0.05) |
Lustre | Vitreous to resinous |
Pleochroism | Weak to moderate |
Beryl is a beryllium aluminum silicate that occurs in every color of the rainbow. When green, it's an emerald. When blue, it's aquamarine. When pink, it's morganite. There is a raspberry red variety found in Utah called Bixbite. Yellow is heliodor and colorless is goshenite. There is a very rare and costly variety termed riesling beryl, that can be described as pale green colour, with a warm golden yellow flash. Two unusually dark blue types of beryl have been found as well, Maxixe beryl and True Blue beryl. Maxixe beryl fades with exposure to light, True Blue beryl does not. Beryl had been used as a physician's tool and gazing stone since ancient times. Those beliefs persist today. Beryl is metaphysically attributed with the ability to cure a number of intestinal and stomach ills, such as nausea, ulcers, and seasickness.
Contents
Characteristics
Genesis
Metamorphic rocks in pegmatites
Localities
Beryl is found in many localities, amongst them are Brazil, India, Africa, Columbia, Australia and Pakistan.
Chemical composition
Beryllium Aluminium sillicate - Be3Al2(SiO3)6
Beryl belongs to the Beryl Group.
Crystal system
Hexagonal.
Habit
Prismatic with pyramidal and pinacoidal terminations. Often vertically striated.
Cleavage
Imperfact, basal.
Hardness
7¼ - 7¾ (Emerald is brittle).
Specific gravity
2.7 to 2.9, depending on variety.
Optical data
Refractive index: nε = 1.56 nω = 1.59, depending on variety.
Birefringence: 0.004 to 0.009, depending on variety.
Optical sign: Uniaxial negative.
Dispersion: low, 0.014
Diapheny
Transparent to translucent.
Colors
- Green (Emerald)
- Green (Vanadium Beryl)
- Green (Reisling Beryl)
- Blue (Aquamarine)
- Blue (Maxixe)
- Blue (True Blue)
- Pink (Morganite)
- Red (Bixbite)
- Yellow (Heliodor)
- Colorless (Goshenite)