Diamonds are typically created more than 800 kilometers (500 miles) below Earth’s surface when temperatures over 2200 degrees Celsius (4000 degrees Fahrenheit) and pressure 1.3 million times greater than the atmosphere combine and crystallize carbon into the clear white stone we all know. Synthetic diamonds can replicate the process in a few short days, creating diamonds that are less politically-charged for use in jewelry, electronics, manufacturing, and more.
Dan Frost of Germany's Bayerisches Geoinstitut has been creating diamonds out of a rather unlikely source of carbon: peanut butter. Frost explained his process to BBC Future’s David Robinson.
While it might sound a bit on the ridiculous side, Frost’s process is allowing him to explore the composition of Earth’s mantle, and even challenge some long-standing assumptions about where some of these elemental components originated. Meteorites and asteroids are assumed to have brought a large amount of material to early Earth, but the amount of silicon found in those bodies is much higher than what can be found in the planet’s crust. To test if the silicon migrated down into the mantle, Frost needs to replicate the environmental conditions of that region.
Heat and pressure similar to conditions within the mantle begin to rearrange the carbon atoms into a dense configuration. Adding more pressure spurs the formation of a diamond, which Frost then bombards with acoustics. The pathway of the sound waves through the gem is then compared to those recorded from seismic waves, allowing Frost to make deductions about the lower mantle’s composition.
Frost found that the lower mantle doesn’t appear to be rich in silicon, which raises more questions about where all of that silicon has gone. Did it migrate all the way to the core? Did it stay on the crust and get kicked out by meteorite impacts? Could scientists be wrong about the amount of silicon was expected to have come to the Earth?
It is unlikely that peanut butter diamonds will be featured in jewelry anytime soon. This method takes weeks to produce a diamond that is 3 millimeters in diameter, which is smaller than a round cut 0.25 carat stone. Additionally, the hydrogen bonded to the carbon atoms are released after the diamond forms, which can cause small explosions.
“It sounds horrific,” he tells BBC Future. “But it’s not dangerous – everything is protected.”
Instead, Frost will focus on the geological and industrial implications of creating diamonds. Though this particular experiment uses peanut butter as the carbon source, minor changes in the recipe could yield stones that have specialized properties. Lacing diamonds with boron could minimize the amount of heat generated when diamonds are used in semiconductors, which is currently a substantial amount. Using carbon nanotubes could add a level of structural support, creating a material stronger than anything on the planet.
[Hat tip: BBC Future]
NOTE: An earlier version of this article incorrectly described the lower mantle as 800 meters beneath the surfaces of the Earth. The correct unit is kilometers, and the article has been updated to reflect that correction.