DIAMOND FORMATION IN THE EARTH’S MANTLE
?Most diamonds are found in commercial mines, but they were actually formed inside the Earth’s mantle, about 150 kilometers below the Earth’s crust. Diamonds are created in something called a “diamond stability zone” in the upper mantle, a high-pressure region that has a temperature of over 1,000 degrees Celsius.
?Diamonds are continually forming and growing there, just as they have been for billions of years. The gems are brought to the surface of the Earth during a seismic event like a volcanic eruption, embedded in large chunks of rocks called xenoliths.
⚒️ DIAMOND FORMATION IN SUBDUCTION ZONES
?Diamonds are also thought to form in “subduction zones,” a.k.a. places where the tectonic plates that are constantly, gradually moving beneath the earth’s surface come together, causing one plate to move underneath the other.
?Some studies suggest that subducted seawater is involved in the formation of diamonds in these zones; others have found these diamonds contain tiny bits of oceanic crust.
💎 Diamonds were formed over 3 billion years ago deep within the Earth’s crust under conditions of intense heat and pressure that cause carbon atoms to crystallise forming diamonds.
💎 Diamonds are found at a depth of approx. 150-200km below the surface of the Earth. Here, temperatures average 900 to 1,300 degrees Celsius and at a pressure of 45 to 60 kilobars (which is around 50,000 times that of atmospheric pressure at the Earth’s surface).
👉 Under these conditions, molten lamproite and kimberlite (commonly known as magma) are also formed within the Earth’s upper mantle and expand at a rapid rate. This expansion causes the magma to erupt, forcing it to the Earth’s surface and taking along with it diamond bearing rocks. Moving at an incredible speed, the magma takes the path with least resistance, forming a ‘pipe’ to the surface.
💎 As it cools the magma hardens to form Kimberlite and settles in vertical structures known as kimberlite pipes. These kimberlite pipes are the most significant source of diamonds, yet it is estimated that only 1 in every 200 kimberlite pipes contain gem-quality diamonds.
👉 The name ‘Kimberlite’ was derived from the South African town of Kimberley where the first diamonds were found in this type of rock.
💎 Coal has rarely – if ever – played a role in the formation of diamonds. In fact, most diamonds that have been dated are much older than Earth’s first land plants – the source material of coal! That alone should be enough evidence to shut down the idea that Earth’s diamond deposits were formed from coal.