How a diamond is like a champagne cork

Why don't diamonds burn up in the Earth's crust?

Wired Science reports on new research revealing the secret behind the rapid ascent of diamonds as they are pushed up from deep below Earth's surface.

It’s difficult to explain how relatively heavy, crystal-rich magma becomes buoyant enough to rapidly rise through Earth’s crust, so researchers have long suspected that volatile substances dissolved in the rock, such as water and carbon dioxide, play a major role in kimberlite eruptions, says Kelly Russell, a volcanologist at the University of British Columbia in Vancouver, Canada.

Russell and his colleagues conducted tests into how the "fizz" gets started:

In the team’s early tests, the researchers used a salt shaker to sprinkle a silica-rich mineral called orthopyroxene onto a puddle of molten, carbonate-rich rock. As the mineral dissolved into the puddle over the course of 20 minutes or so, the carbon dioxide vigorously bubbled out: “It foamed right in front of our eyes,” Russell says. “It blew me away.”

The lab tests mimic what happens in an actual kimberlite eruption:

As the magma surges upward from the upper mantle at speeds up to 14 kilometers per hour, it pummels its way into overlying rocks that contain even more silica, which accelerates the fizzing even further. At such rates, the frothy kimberlite lava could reach Earth’s surface from a depth of up to 120 kilometers in between 3 and 8 hours, Russell estimates.