The glitter of diamonds, the perfection of their facets and their scintillating fire always makes one wonder that how did these
shining beauties come to existence? Diamonds are formed under certain precise
conditions in the deep interiors of the earth. These sparkling fruits of nature
are believed to be more than billions of years old and form under the stable
continental plates. In this post we will unearth the
procedure of diamond formation.
The formation of diamonds takes place under extreme conditions.
Diamonds form mostly in the mantle which is below the surface layer of the
earth at a distance of approximately 150 Kms. When carbon crystals are
subjected to a temperature of 1050° C and a
pressure of 45000-60000 Kilobars, is when the process of diamond formation
begins. These conditions are not present uniformly in the layers of the earth.
These conditions mostly exist under the stable continental plates. These
stable parts are called cratons.
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| CRATONS |
It is a fairly common belief that when a person or an object is
subjected to immense pressure and difficulties they either they crack or come
out victorious. The same is with the diamonds they undergo extreme heat and
pressure in the interiors of the earth
but a slight change in the conditions can lead to formation of graphite.
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| GRAPHITE |
There are two types of diamonds – P Type and E Type. P type diamonds
are formed with the help of peridotitic rocks and E type are formed with the
assistance of eclogitic rocks.
Peridotite and eclogite are referred to as source rocks as the diamonds
form in these igneous rocks. These rocks exist under the earth in a molten
state and they continuously emit carbon. The carbon atoms under the immense
heat and pressure of the earth’s interiors start locking with each other. If
the conditions are accurate diamond crystals start forming.
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| PERIDOTITE |
Diamonds formed in the mantle are brought up to earth’s surface by
the deep volcanic eruptions. These eruptions break the mantle and bring the
diamonds to the surface. The rocks which transport the diamonds are kimberlite
and lamproite. Kimberlite and lamproite are formed in the molten magma in the
mantle. The magma expands as it heats up
and it passes through a fracture in the crust. While passing through a fracture
it might come in contact with a diamond deposit and carry the diamonds along
with it. The magma then continues to rise and the pressure decreases. With the
decrease in pressure magma is able to travel at a very high speed of about 300
Kms/hour. At this stage some chemicals start to vaporise into carbon dioxide
and water vapour. The speed of magma along with release of gases leads to an
explosion. At this very point kimberlite pipes are formed. These pipes are
where the majority of diamonds are found.
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| KIMBERLITE PIPE |
Any change in vaporisation and the speed of magma can result in
formation of graphite. The kimberlite or lamproite then solidifies creating a
diamond rich deposit. This is what most of the diamond miners hunt for.
Diamonds go through a lot before one sees them glittering in a
store’s display. They undergo extreme heat and pressure and are brought to the
earth by violent eruptions. For years together they trapped there until
unearthed by man. Thereafter, they are cut and polished and that’s when one
sees the real beauty of diamonds. And
that is why it is said, to have an understanding of diamond formation is
extremely important not only from technical aspects but also because so that
one can appreciate this unique process and also how rare are fine gem quality
diamonds.
