The Origin of Diamonds
Diamonds were formed in the earth’s upper mantle layers approximately 2.5 billion years ago, 150-200km down from the crust at temperatures of about 1300°C and pressures between 45-60 kilobars. The diamond crystals are thus formed in the liquid rock mass of the upper mantle. Volcanic activity is required to bring the diamonds to the surface of the earth. It is, therefore, vital to know that kimberlites and lamproites are the only transport materials to move the diamonds to the earth’s surface.
The diamond-containing transport magma paves its way to the earth’s surface along existing deep crevices and cracks in the earth’s crust. At less than a depth of 2 km, pressure differences produce a huge explosion. This explosion leads to a large crate filled with chunks of kimberlite. However, this does not mean that diamonds are only found in kimberlite pipes; they can, for example, also be found in the dune sand along the Namibian coast.