Emerald
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 | |
|---|---|
_-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] |
Etymology
The word emerald comes from Vulgar Latin. The word was Esmaralda/Esmaraldus, a different way of saying the Latin word Smaragdus, which came from the Greek, σμάραγδος (smaragdos; "green gem").[2][3] It first came from a Semitic word, izmargad (אזמרגד). This meant "emerald" or "green".[2] The name could also be related to the Semitic word baraq (בָּרָק ;البُراق; "lightning" or "shine") (c.f. Hebrew: ברקת bareqeth and Arabic: برق, barq, "lightning"). It is where the Persian (زمرّد zomorrod), Turkish (zümrüt), Sanskrit (मरग्दम् maragdam) and Russian (изумруд; izumrúd) words came from.[3]
Emerald Media
Main emerald producing countries
Colombian emeralds faceted in emerald cut
Brazilian emerald (grass-green variety of the mineral beryl) in a quartz-pegmatite matrix with typical hexagonal, prismatic crystals.
A Colombian trapiche emerald
Emerald showing its hexagonal structure
Emerald made by hydrothermal synthesis
Emerald on quartz, from Carnaiba Mine, Pindobaçu, Campo Formoso ultramafic complex, Bahia, Brazil
The Chalk Emerald ring, containing a top-quality 37-carat emerald, in the U.S. National Museum of Natural History
Зүмірет тасы
A 5-carat emerald from Muzo with hexagonal cross-section
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Related pages
References
- ↑ "Emerald at Mindat". Mindat.org. 2010-07-19. Retrieved 2010-07-30.
- ↑ 2.0 2.1 Fernie M.D., W.T. (1906). Precious Stones for Curative Wear. John Wright. & Co.
- ↑ 3.0 3.1 "Online Etymology Dictionary". etymonline.com. Retrieved 15 April 2010.