Deep Earth diamond with garnet inside.  These inclusions, which occur during the diamond formation process, provide not only a way to date the diamonds, but also a window into conditions in deep Earth when they wee formed.  (M. Gress, VU Amsterdam)

We all know that cut diamonds sparkle and shine, one of the great aesthetic creations from nature.

Less well known is that diamonds and the bits of minerals, gases and water encased in them offer a unique opportunity to probe the deepest regions of our planet.

Thought to be some of the oldest available materials found on Earth — some dated at up to 3.5 billion years old — they crystallize at great depth and under great pressure.

But from the point of view of those who study them, it’s the inclusions that loom large because allow them to know the age and depth of the diamond’s formation. And some think they can ultimately provide important clues to major scientific questions about the origin of water on Earth and even the origin of life.

The strange and remarkable subterranean world where the diamonds are formed has, of course, never been visited, but has been intensively studied using a variety of indirect measurements.  And this field has in recent weeks gotten some important discoveries based on those diamond inclusions.

First is the identification by Fabrizio Nestola of the Department of Geosciences at the University of Padua and colleagues of a mineral that has been theorized to be the fourth most  common on Earth, yet had never been found in nature or successfully synthesized in a laboratory.  As reported in the journal Nature, the mineral is a variant of calcium silicate (CaSiO3), created at a high pressure that gives it a uniquely deep-earth crystal structure called “perovskite,” which is the name of a mineral, too.

Mineral science does not allow a specimen to be named until it has actually been found in name, and now this very common form of mineral finally will get a name. But more important, it moves forward our understanding of what happens far below the Earth’s surface.

 

 

Where diamonds are formed and found on Earth. The super-deep are produced very far into the mantle and are pushed up by volcanoes and convection  The lithospheric diamonds are from the rigid upper mantle and crust and the alluvial diamonds are those which came to the surface and then were transported elsewhere by natural forces.

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