Zircon crystals. Photograph by Rob Lavinsky, iRocks.com
A zircon crystal found on a sheep farm in Jack Hills, Western Australia was formed 4.4 billion years ago, making it the oldest piece of the Earth yet discovered.
The tiny crystal, measuring only 200 by 400 microns, was found in 2001, but scientists decided to wait for two separate dating techniques to verify the results due to their significance on scientific understanding of how the earth was formed. The scientists first dated the gem using the radioactive decay of uranium to lead, and then verified their results by using atom-probe tomography.
In a report published in the journal Nature Geoscience, researchers from the University of Wisconsin led by professor John Valley said that the age of the crystal shows that the Earth’s crust formed more rapidly than previously thought, making the planet cool enough to sustain large bodies of water and more hospitable to life for a longer period.
