How Diamonds Form

How diamonds form

A lot of people mistakenly believe that diamonds are
formed through the metamorphism of coal. The truth is that coal hardly ever has
a role in the formation of diamond. One fact that would kill that hypothesis is
that coals form through horizontal sedimentary rocks while diamonds are formed
in vertical pipes of igneous rocks.

Diamonds are formed in four ways naturally the first one
listed below being the one responsible for almost 100% of the diamonds mined.

In Earth’s Mantle

Most of the diamonds that we know today are formed in the
earth’s mantle and are brought to the surface through volcanic eruptions. The
eruptions form kimberlite and sometimes lamproite pipes which miners drill into
to find diamonds. Some the diamonds found in these deposits might get eroded by
rivers, streams and oceans.

Natural diamonds form under extremely high pressures and
temperatures within the very specific zones of the earth’s mantle. This is
about ninety miles from the earth’s surface where the temperatures could be in
the region of 2000 degrees Fahrenheit.

The ideal temperate and pressure for the formation of
diamonds only occurs in certain areas; in the mantle under the inside of the continental
plates. The diamonds are stored once formed in these stable zones and only come
to the surface through certain volcanic eruptions. When the volcano erupts it
destroys parts of the mantle and takes them to the surface. These eruptions are
quite rare.

Putting an End to
the Coal Hypothesis

Coal is a sedimentary rock that is formed from decayed
plants on the earth’s surface. Coals can rarely be found deeper than 2 miles
within the earth. It is almost preposterous to think that coal can travel as
far into the earth as the continental plate. The carbon source for diamond them
comes most likely from carbon trapped within the depths of the earth.

In Subduction

Small bits of diamonds were discovered in rocks
subduction zones. This can occur at about 50 miles within the earth where the
temperatures might be about 400 degrees Fahrenheit. In this instance coal might
be a possible source of carbon but most likely the source could be from oceanic
plates which provide limestone, dolomite, offshore sediments and marble; all
good sources of carbon.

At Impact Sites

Large asteroids have impacted the earth throughout
history producing high pressures and temperatures. The energy burst of the
impact is what increases the temperature and the pressure. This creates the
ideal environment for diamonds to form.

Several diamonds have been discovered at sites like these thus confirming the validity of this
theory. Coal in this case might be the carbon source as well as limestone and common
carbon composed rocks.

In Space

Researchers at NASA have found nanodiamonds (very tiny
diamonds) in a few meteorites. Up to 3 percent of the carbon contained the
meteorites come from diamonds. They are way too small to be used as gems. They
form in space when meteorites collide with each other in space at high speeds.

Carbon dating of diamond shows that they were formed
millions of years ago well before the first plant was ever found on earth.
Since coals are formed from plant debris it goes to show that they cannot be
the source of carbon for diamonds as we know it.

By: Kole McRae for Wedding Bands

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