On Sunday, scientists claimed that they figured out how world’s largest diamonds are formed. A news agency reported that large gem quality diamonds might have formed in the metallic liquid inside the Earth’s mantle. A study about this discovery was published in the US journal Science.
Evan Smith, the research team lead of Gemological Institute of America came to this conclusion after examining off-cut of massive diamonds. These are left over gem facets that are cut for maximum sparkle. The team found metallic grains trapped inside 30 large stones. These metallic mixtures were made of iron, nickel, sulfur, methane and traces of Hydrogen.
This mixture led the scientists to conclude that these diamonds formed under earth’s mantle. But unlike other diamonds, these formed under pressure of metallic liquids. Diamonds generally are found at 150 km to 200 km under the Earth and come to the surface through volcanic emissions.
In a statement the team explained, “Pure carbon crystallized in this mix of molten metallic liquid in Earth’s deep mantle to form diamonds.” They also said , “Small droplets of this metallic liquid were occasionally trapped within the diamonds as they grew.” This analysis offers useful clues that help in the advance understanding of Earth’s deep mantle, hidden beneath tectonic plates, these large diamonds are inaccessible for scientific observation. The findings may also explain to the scientists the availability of oxygen in the mantle.
Closer to the surface, the chemistry of the mantle is more oxidized, scientists can explain this from the presence of carbon in the form of carbon dioxide in the lava emitted by the volcanoes. Often times Lamproite and Kimberlite stones, under pressure also helps in the formation of diamonds closer to the surface of the earth. But those formed closer to surface are not very large diamonds.
