Found on a sheep ranch in the Jack Hills region of Australia, this piece of zircon is 400 micrometers long, which is about twice the width of a human hair, and is now confirmed to be the oldest bit of the Earth’s crust ever discovered, according to CBC News. Zircon is ubiquitous in the crust of Earth. It occurs in igneous rocks.
Lead study author and professor in the Department of Geoscience at the University of Wisconsin-Madison, John Valley, reported “This is the oldest and the best dated of all the crystals that have been reported,” according to CNN News. For a rock of such importance, it is rather small. Large zircon crystals are very rare.
Two scientists at Western University in London, Desmond Moser and Ivan Barker, checked the crystal for signs of meteorite impact and crystal damage. This allowed for them to identify the best-preserved parts of the crystal to probe. Because of their uranium and thorium content, some zircons undergo metamictization, which is a disruption of the crystals structure.
The crystal, according to scientists, suggests that the temperatures on Earth 4.4 billion years ago would have supported liquid water, and therefore perhaps life. Atom-probe tomography confirmed that the zircon was 4.4 billion years old. The age of the crystal means that the crust appeared just 160 million years after the very formation of the solar system as well.
“This may also help us understand how other habitable planets would form,” shared University of Wisconsin-Madison geoscience Professor John Valley. This study reinforces the conclusions that Earth had a hydrosphere before 4.3 billion years ago. And the 4.4 billion-year-old zircon crystal is providing new insights into how the Earth cooled from a ball of hot magma.
Australia leads the world in zircon mining, producing 37% of the world’s total and also accounting for 40% of world economic demonstrated resources for the mineral zircon.
Image Credit: www.jsonline.com