green gemstone, a beryl variety

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 crystals from Muzo, Colombia
CategoryBeryl variety
(repeating unit)
Crystal symmetry(6/m 2/m 2/m) – Dihexagonal Dipyramidal
Unit cella = 9.21 Å, c = 9.19 Å; Z = 2
Molecular mass537.50
ColorGreen shades
Crystal habitMassive to well Crystalline
Crystal systemHexagonal (6/m 2/m 2/m) Space group: P6/mсc
CleavageImperfect on the [0001]
Mohs scale hardness7.5–8
DiaphaneityTransparent to opaque
Specific gravityAverage 2.76
Optical propertiesUniaxial (-)
Refractive indexnω = 1.564–1.595,
nε = 1.568–1.602
Birefringenceδ = 0.0040–0.0070
Ultraviolet fluorescenceNone (some fracture filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not)

Etymology change

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]

Related pages change

References change

  1. "Emerald at Mindat". Mindat.org. 2010-07-19. Retrieved 2010-07-30.
  2. 2.0 2.1 Fernie M.D., W.T. (1906). Precious Stones for Curative Wear. John Wright. & Co.
  3. 3.0 3.1 "Online Etymology Dictionary". etymonline.com. Retrieved 15 April 2010.