Monday, 12 December 2016

Emerald

What is Emerald?

Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) coloured green by trace amounts of chromium and sometimes vanadiumBeryl has a hardness of 7.5–8 on the Mohs scale.Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor. Emerald is a cyclosilicate.

History

Emerald has been a source of fascination and reverence in many cultures for over six thousand years, sold in the markets of Babylon as early as 4,000 B.C. It was a stone worshipped by the Incas, believed by the Chaldeans to contain a goddess, and was highly honoured in all major religions for its spiritual power and beauty. Emerald was considered a symbol of eternal life in ancient Egypt, a gift of Thoth, the god of wisdom, and was a favourite jewel of Queen Cleopatra. The Emerald mines in Upper Egypt, rediscovered a hundred years ago, are some of the oldest in the world and were called Cleopatra’s mines for her love of the stone. Emeralds were also talismans of Aristotle, Alexander the Great, Charlemagne, and the moguls of India. They’ve adorned the crowns and royal jewels of many countries for centuries, and fabulous collections and stunning gems continue to be treasured and displayed by the rich and famous today
The pure exuberance of Emerald’s green colour has inspired the Pantone Company, the industry standard for print, fashion, beauty and d├ęcor to declare “Emerald” the 2013 Colour of the Year, describing it as “Lively. Radiant. Lush, a colour of elegance and beauty that enhances our sense of well-being, balance and harmony.”
Natural, transparent Emerald is one of four “precious” gemstones (including Diamond, Ruby and Sapphire), and is the green variety of Beryl, a beryllium aluminium silicate mineral coloured by trace amounts of chromium and/or vanadium. Emerald occurs in hues ranging from yellow-green to blue-green, with the finest being a pure verdant green hue, medium to dark in tone. Light coloured gems are usually known by the species name, Green Beryl. Most Emeralds are highly included with surface breaking fissures, so their toughness, or resistance to breakage, is usually classified as generally poor. 
According to Indian lore, the name Emerald was first translated from Sanskrit as Marakata, meaning “the green of growing things.” The term we use today is believed to derive from an ancient Persian word that translated to the Greek as Smaragdus, meaning “green stone,” the term used in antiquity and referred to a number of other green stones. Over time the Old French or Vulgar Latin versions, Esmeraulde, Esmaraldaor Esmaraldus became the current name, Emerald.

Occurrence

Emeralds in antiquity have been mined in Egypt since 1500 BCE, and India, and Austria since at least the 14th century CE.
Colombia is by far the world's largest producer of emeralds, constituting 50–95% of the world production, with the number depending on the year, source and grade. Emerald production in Colombia has increased drastically in the last decade, increasing by 78% from 2000 to 2010. The three main emerald mining areas in Colombia are Muzo, Coscuez, and Chivor. Rare "trapiche" emeralds are found in Colombia, distinguished by ray-like spokes of dark impurities.
Zambia is the world's second biggest producer, with its Kafubu River area deposits (Kagem Mines) about 45 km (28 mi) southwest of Kitwe responsible for 20% of the world's production of gem quality stones in 2004. In the first half of 2011 the Kagem mines produced 3.74 tons of emeralds.
Emeralds are found all over the world in countries such as Afghanistan, Australia, Austria, Brazil, Bulgaria, Cambodia, Canada, China, Egypt, Ethiopia, France, Germany, India, Italy, Kazakhstan, Madagascar, Mozambique, Namibia, Nigeria, Norway, Pakistan, Russia, Somalia, South Africa, Spain, Switzerland, Tanzania, United States, Zambia, and Zimbabwe. In the US, emeralds have been found in Connecticut, Montana, Nevada, North Carolina, and South Carolina. In Canada, in 1997 emeralds were discovered in the Yukon.

Properties of Emerald

Chemical FormulaBe3Al2SiO6
ColourGreen
Hardness7.5 - 8
Crystal SystemHexagonal
Refractive Index1.57 - 1.58
SG2.6 - 2.8
TransparencyTransparent to translucent
Double Refraction.006
LusterVitreous
Cleavage3,1 - basal
Mineral ClassBeryl (Emerald)