DIAMONDS AND VOLCANOES | VOLCANO ACTIVE FOUNDATION

All that is known about the conditions under which diamonds were created comes from theories of scientific experiments in the production of synthetic diamonds. According to the most famous, diamonds were formed in liquid magma while cooling under pressure and at a temperature of over 1300 degrees. This pressure and temperature only exist at depths of 130 to 200 km below the Earth’s surface in active volcanoes.

The peculiarity of diamonds

The chemical composition of magma is not uniform, so there are two types of diamonds: Type 1 diamonds with nitrogen in their atomic structure and Type 2, without nitrogen. When the two forces of formation, temperature, and pressure, are not homogeneous, the diamonds thus created show irregularities and malformations such as strata or growth layers.

Diamonds are formed in the bowels of the Earth, at great depth and high temperature. They come to the surface during volcanic eruptions. They are found trapped in magmatic rocks called kimberlites.

The formation of diamonds

Formed at a depth of around 180 km, diamonds are transported to the Earth’s surface by magmas called kimberlites. These magmas are then ejected by volcanoes and cool to form magmatic rocks containing diamond enclaves. However, these magmas are very special. They form at great depth, at the lithosphere-asthenosphere boundary, more than 150 kilometers into the Earth’s mantle, and are characteristic of certain areas of the Earth’s surface. Indeed, kimberlites are observed preferentially in cratonic regions, characterized by a very old continental lithosphere.

Diamonds are carried by eruptive rocks

If during crystallisation, diamonds are not exposed to air to cool and reduce in pressure quickly, they will turn into graphite. It seems, therefore, that diamonds must emerge from the bowels of the earth with the eruption of volcanic rocks. Diamonds are carried by eruptive rocks, pipes and dykes that contain kimberlite or lamproitic rocks. Pipes, as miners call them, are 100 million to 1.2 billion years old; these violent eruptions of volcanic rocks could not happen today. As old continents drifted and then reassembled to form new ones, these pipes were distributed across the globe. Today, 80% of diamonds are mined in the 7 main producing countries: Australia, Congo, Botswana, South Africa, Russia, Namibia and Angola.

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Diamond deposits

There are 2 types of diamond deposits. Primary deposits consist of pipes and dykes that contain kimberlite rocks, the pathways that diamonds took to reach the earth’s surface. These deposits are mined using complicated, invasive and environmentally damaging industrial technology. As they weather, the diamonds break away from the primary rock and are carried away by runoff, streams and rivers. They are then dispersed along their path. The deposits formed in this way are called secondary or alluvial deposits. The distance travelled by alluvial diamonds varies greatly and can sometimes be considerable, as they can be washed down to beaches or the seabed. These diamonds can be extracted using manual artisanal techniques, while respecting nature.

THE BOND BETWEEN DIAMONDS AND VOLCANOES

Diamonds are one of nature’s oldest creations

The peculiarity of diamonds

The formation of diamonds

Diamonds are carried by eruptive rocks

Diamond deposits

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