Sparkling blue gem reveals origins of Earth's crust

(Image: John Valley)

This dazzling blue crystal looks sparkling and new, but it is actually about 4.4 billion years old, making it one of the oldest known pieces of Earth’s crust. The zircon crystal from the Jack Hills in Western Australia is less than a millimetre wide, but it gives us a huge insight into the history of our planet.

Zircons from the Jack Hills are already recognised as the oldest known material of any kind formed on Earth. But researchers analysing the atomic structure of this tiny shard have been able to pin down its history more accurately than ever before.

Previous efforts to date zircon had proved controversial, but a new measurement technique called atom-probe tomography has now laid the issue to rest.

Earth and the moon are thought to have formed just 100 million years earlier than the zircon sample, so determining its age helps refine models of how our new-born planet’s crust cooled.