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Scientists have announced that some tiny zircon crystals, small enough that you need a magnifying glass, are 4.4 billion years old.
The crystals were found on a western Australian sheep farm, the Los Angeles Times reports. The location, which is known to be a fairly stable part of the Earth, helped keep the zircon crystals around.
Professor John Valley, of geoscience at the University of Wisconsin-Madison and who also discovered the crystal, said, "The Earth's tectonic processes are constantly destroying rocks." He added, "This may be one place where the oldest material has been preserved."
The scientists involved in dating the rock have published their study in the upcoming issue of Nature Geoscience. Valley and his team dated the crystals twice just to be sure they had the date right.
One process used to date the 4.4 billion-year-old crystal is called the uranium lead system and checks to see how many of the uranium atoms inside of the crystal have decayed into lead. They also used another dating method called atom-probe tomography to please some of their critics who felt the findings from their other method were possibly flawed.
According to NPR, geologist Sam Bowring, of the Massachusetts Institute of Technology, said, "I think people will be impressed with the technique and impressed with the conclusions [of the study] and agree with them."
The zircon crystals Valley discovered are the oldest ever discovered and come from a time when the Earth was still forming and had yet to support life. The crystals formed shortly after something hit the Earth and created the moon. The planet "would have glowed almost like a star. Nothing could exist on the surface. There would be no continental land masses. There'd be no liquid water," Valley said.