Emerald

What is Emerald?

Emerald is widely known as precious gemstone having distinctive green colour. It is one of the mineral Beryl variety OF Beryl family (Be3Al2(SiO3)6). The green colour is due to the presence of chromium and Vandaium. At Mohun Scale, the hardness of beryl is 7.5-8. The quantity of emerald around the world is traced in a small amount. They are found in ingenous, sedimentary and metamorphic rocks.

Chemical Formula Be3Al2Si6O18
Colour Green
Hardness 7.5-8
Refractive Index 1.57 – 1.58
SG 2.6 – 2.8
Crystal System Hexagonal ,  Often as prismatic crystals.
Clarity Almost every natural emerald has eye-visible characteristics that can be inclusions, surface-reaching fractures, or healed fractures.
Luster Vitreous
Cleavage 3,1 – basal
Durability Emerald is very hard, but almost all specimens have inclusions and surface-reaching fractures that compromise their durability.
Fracture Uneven to conchoidal
Tenacity Brittle
In Group Silicates; Cyclosilicates
Rock Type Igneous, Metamorphic

St. Hildegard of Bingen, the noted lithologist, declared,

“All the green of nature is concentrated within the Emerald.”

History of Emerald

Emerald has been used in ancient Egypt and Mediterranean regions. Emerald or green beryl was used to be mined only in Egypt or Egypt was the only source of mining in that era i.e Wadi Sikait and also 15 kilometers from the Valley. Emerald mining was started first in 4th through mid- 1st centuries BC.

Emerald traces are also observed in Austria during the Roman Period though there is no any decisive evidence about it. In ancient Egypt, the usage of stones in different forms was popular and is quite evident from archaeological and geographical researches. They used to build buildings, pyramids, used to create ornamental stones for statues, vessels and precious stones for jewelry. 100 years ago, emerald mines were rediscovered in Upper Egypt which was named as Cleopatra’s mines for her love of the stone.

 

Many civilizations and cultures used to be fascinated by the beauty of emerald over 6000 years ago? In early 4000 BC, it was marketed in Babylon. Ancient Egypt used to take emerald as symbol of eternal life.

What are Geological and Geographic Occurrences of Emerald?

Emerald is variety of green Beryl. Beryl is a Beryllium Alumino – Silicate Mineral occasionally with some sodium, lithium, and cesium which is a rare mineral on earth. Its chemical formula is Be3Al2(SiO3)6. Beryllium is an element which occurs in very small amounts in the crust of earth.  Normally Beryl is colorless. The inclusion or presence of trace impurities gives colour to gemstones which is a variety of beryl. For example, green emerald, blue aquamarine, goshenite, pink Morganite, yellow to yellowish heliodor. Its hardness at Mohs is 7.5 – 8.

Beryl has variety of colours such as green to green emerald colour, blue to green blue like found in Aquamarine, yellow, pink in Morganite, purple, red, orange, brown, white like in goshenite, yellow to yellow heliodor, colourless, white, gray.

How Emerald Green Colour Formed?

Emerald is variety of Beryl which is colorless in ordinary form. Colorless beryl is called goshenite. Some trace amount of chromium or vanadium cause to grow a green color.

 

 

 

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