A dirty, $10 diamond with a prize inside has helped reveal that there are vast quantities of water stored deep inside the Earth.

The diamond formed in the "transition zone" around 410 to 660 kilometres below our planet's surface. Analysis of a mineral grain trapped inside it suggests that it came from surroundings that were about one per cent water, report researchers led by University of Alberta geochemist Graham Pearson. They published their findings online in the journal Nature today.

If the sample is representative of that part of the deep Earth, the amount of water there could be "about the same as the mass of all the world’s oceans combined," wrote Hans Keppler, a geophysicist at the University of Bayreuth in Germany, in an analysis article.

That, in turn, changes our understanding of the way water cycles through our planet, and has implications for the way tectonic plates and volcanoes behave, Pearson notes.

Source: CBC News - see full article