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Emerald
| Emerald | |
|---|---|
_-2.jpg) Emerald crystals from Muzo, Colombia | |
| General | |
| Category | Beryl variety |
| Formula (repeating unit) | Be3Al2(SiO3)6 |
| Crystal symmetry | (6/m 2/m 2/m) – Dihexagonal Dipyramidal |
| Unit cell | a = 9.21 Å, c = 9.19 Å; Z = 2 |
| Identification | |
| Molecular mass | 537.50 |
| Color | Green shades |
| Crystal habit | Massive to well Crystalline |
| Crystal system | Hexagonal (6/m 2/m 2/m) Space group: P6/mсc |
| Cleavage | Imperfect on the [0001] |
| Fracture | Conchoidal |
| Mohs scale hardness | 7.5–8 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent to opaque |
| Specific gravity | Average 2.76 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.564–1.595, nε = 1.568–1.602 |
| Birefringence | δ = 0.0040–0.0070 |
| Ultraviolet fluorescence | None (some fracture filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not) |
| References | [1] |
An emerald is a mineral gemstone and a variety of beryl. It is the birthstone of someone whose birthday is in the month of May. It is a green crystal. The emerald is one of the most valuable gems, along with the ruby, the opal, topaz, the diamond, and a sapphire.
- ↑ "Emerald at Mindat". Mindat.org. 2010-07-19. Retrieved 2010-07-30.
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