Onyx Mining

Description

Precious stones have an important significance in the life of all people. Onyx is one of the rarest variety of precious stones found in different parts of the world and is available in almost all colors except for few colors like violet blue etc. Onyx with its flesh stone colour gives a resemblance of a fingernail.

Onyx is cryptocrystalline and we can find intergrowths of silica minerals quartz and moganite in it. Another variety of onyx is Sardonyx which comes in red and black colour. Moreover artificial coloring is also given to it since ancient times to make it appear red or black. Piny the Elder describes various techniques used during Roman times to produce different colors of onyx stone .Dyeing treatment is also used and most of the black onyx sold is artificially treated. The black onyx stones because of its elegancy it is used to make jewellery. There are other black gems like diamond, sapphire etc. but as onyx is cheaper compared to other gems it is used by many people.

The stone is carved polished and sold as onyx stone in places like Mexico, Pakistan. However the original onyx is not as soft as artificial ones. The Onyx stones are also carved and made into jewellery which caters to the demands of the jewelers around the world. The beads made out of onyx stone is always a feast to our eyes. The natural onyx are rarely found as most of it is produced by artificial treatment and sold in the market in the form of jewellery. If we go through the history of Egypt it can be noticed that onyx in ancient times was used to make bowls and pottery. Green onyx found in Brazil was used to decorate sculptures created in the early nineteenth century. In the Bible too we can find the mention of onyx stone. Another important fact is that there is a vast difference between onyx stone and onyx marble which is also widely available in the market and used for various decorative items. However Onyx marble is nothing but the lime stone. Onyx stones are associated with lots of myths also.

The stones are generally believed to give lots of positive vibration and it is also believed that fear and anxiety too is eliminated with the use of onyx stone. Lots of diseases are also cured with help of onyx stone. Though there are lot of positive beliefs about onyx gem stone it is also believed by some that onyx stones are unlucky too. But the truth is that it has more positive properties than negative properties. The Great Cameo of France made out of onyx gem stone is exhibited in the Bibilothique national in France. Another famous Cameo gem of Augustus is also made up of a peculiar onyx stone called Arabian onyx. Onyx stones though a tough substance, it has to be taken care to keep in the best of conditions. The jewellery made of Onyx stones are kept in good condition by cleaning with a clean cloth soaked in soapy water. It is better to store onyx stone away from other gem stones as there are chances of it easily getting damaged. Onyx is a very precious gem and because of its character it is widely used in jewellery and artificial ornamentation.

Physical Properties :-


Name

Onyx

Is a Variety of

Chalcedony

Varieties

Sardonyx

Crystallography 

Hexagonal (trigonal), microcrystalline

Refractive Index 

1.544-1.553

Colors 

Black, white (banded). Varieties may show red, brown, yellow, and blue layers. Solid black onyx may also occur, though most such specimens are dyed.

Luster 

Waxy

Polish Luster

Vitreous

Hardness 

7

Wearability 

Excellent

Fracture 

Conchoidal

Specific Gravity 

2.651

Birefringence 

0.009

Cleavage 

None

Dispersion 

None

Heat Sensitivity

No

Enhancements

Dyeing, heating (common)

Typical Treatments

Dyeing, Heat Treatment

Transparency 

Opaque

Formula

SiO2

Pleochroism 

None

Optics 

Uniaxial (+)

Optic Sign

Uniaxial +

Etymology

From the Greek word for “fingernail” or “claw.”

Occurrence

Can occur in a wide variety of mineral environments.


Onyx is a form of chalcedony, part of the quartz group. Like the other stones in the chalcedony family, onyx has a smooth, waxy luster. Onyx can be found in a wide range of colors, often layered.

Specific Gravity of onyx is 2.58 - 2.64, Refractive Index of the stone is 1.55 - 1.54, Hardness of onyx is 6.5 - 7.0 on Moh's scale

Natural Occurrence :

Mexico, Arizona, Algeria

Available Colors :

White and Black

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