New research suggests diamonds are not as rare as we thought they were, and are actually abundant deep within the Earth.
These findings "constitute a new quantitative theory of diamond formation," but do not mean gem-quality diamonds will be easier to find or drop in value, Johns Hopkins University reported. In order to reach Earth's surface and be easily mined, diamonds must be carried by rare eruptions of magma. The diamonds looked at in this study were also generally microscopic, or nowhere near the size required to make a piece of jewelry.
The researchers found diamonds could be formed through natural chemical reactions simpler than the processes previously believed to be the only way the gems could be born. This new research suggests diamonds are formed in the movement of fluid by the oxidation of methane or the chemical reduction of carbon dioxide. Oxidation leads to a gain in electrons, while reduction means a lower oxidative state; these are known as "redox reactions."
"It was always hard to explain why the redox reactions took place," said Johns Hopkins geochemist Dimitri A. Sverjensky.
These reactions require different types of fluids to be moved through rocks that are exposed to different oxidative states. The team found water can produce diamonds if the pH falls as it moves throught the rocks.
"The more people look, the more they're finding diamonds in different rock types now," Sverjensky said. "I think everybody would agree there's more and more environments of diamond formation being discovered."
The deepest drilling expedition has reached only eight or nine miles below the surface, but these lab experiments could provide a glimpse into what the Earth looks like much deeper below. The findings also shed light on fluid movement deep within the planet, which could give us insight into the carbon cycle on the surface.
"Fluids are the key link between the shallow and the deep Earth," Sverjensky said. "That's why it's important."
The findings were published in a recent edition of the journal Nature Communications.
