The tiny fragment of zircon was found in 2001 on an outback sheep station in Western Australia by University of Wisconsin geoscience professor John Valley. At the time, he had been on a field trip to an area called Jack Hills, located north of Perth.
An international team of scientists, led by Valley, conducted a study on the gemstone, which revealed that the Earth’s crust first formed at least 4.4 billion years ago, 160 million years after the formation of the solar system.
According to Valley, the research – published in the journal Nature Geoscience – showed that the time when the planet was a fiery ball covered in magma ocean came earlier.
“This confirms our view of how the Earth cooled and became habitable,” Valley said. “This may also help us understand how other habitable planets would form.”
The study, which used a new technique called atom-probe tomography, builds on earlier research that relied on lead isotopes to date Australian zircons and identify them as the oldest bits of the Earth’s crust.
Valley said that the study “reinforces our conclusion that Earth had a hydrosphere before 4.3 billion years ago” and possibly life not long after.
The zircon in question measures only about 200 by 400 microns, approximately twice the diameter of a human hair.
The Jack Hills region is renowned for its ancient gemstones that help provide insight into the conditions on Earth.
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