Rare Object
‘It’s pretty rare to get a piece of magma that is 2.7 billion years old.’ explains Dr Andrew Berry from Imperial College London’s Department of Earth Science and Engineering. And Berry and his team have used it to uncover the Earth’s early history.

Collider technology
Dr Berry, who lead a research team on the project from the US and Australia, developed a technique for analysing the oxidation state of Fe, Iron, in minute samples of glass/magma, in this instance a piece of komatiite magmatic rock. ‘The technique we used,’ explains Dr Berry, ‘X-ray Absorption Spectroscopy (XAS), is essentially the only possible way to solve this problem.  XAS requires access to a synchrotron light source, km-size particle accelerators that produce high intensity X-rays. We conducted the experiment at the Advanced Photon Source at Argonne National Laboratory in the US, but it could now be done at the new UK Synchrotron Diamond.’ ‘These technologies’ says Berry ‘are really big instruments, a bit like the Hadron collidor in CERN. It’s a similar sort of thing in that you have particles going round in a big circle, almost at the speed of light.’

Jurassic Park
The team was working with a sample of rock that had been preserved in a crystal, as normally in the atmosphere it would rust, degrade and turn to soil. ‘It was a bit like Jurassic Park, where insects are trapped inside amber. We had an Olivine crystal and a little bit of magma was trapped inside it, that’s what allowed it to be preserved for 2.7 billion years. It’s only about 30 microns or 50 microns in size, sub-sub millimetre, and we were able to look at it using the synchrotron technique.’

The results revealed that the temperature of the earth’s mantle has cooled by 300 degrees Celsius over the 2.7 billion years. And Dr Berry is already applying the new method to different samples. ‘The project I was doing two weeks ago, at the Diamond Synchrotron, was to look at tiny fragments of meteorites that formed very early on in the solar system’s history, basically looking back in time at what the solar system was like at the very beginning, before the planets were formed and there was just a big mass of dust swirling around.’