Zircon grain found in Western Australia's Jack Hills is 4.4 billion years old, making it the oldest known terrestrial mineral grain - ECOticias.com

A zircon grain from Jack Hills in Western Australia has been dated to about 4.4 billion years old, making it the oldest known terrestrial mineral grain. The result aligns with a 2025 lunar study that pushed back the Moon’s final solidification phase to roughly the same period. The 4 mm-wide specimen was first dated in 2001 using uranium-lead methods and later confirmed in 2014 with atom-probe tomography. Oxygen isotope chemistry suggests it interacted with cold water before crystallization, providing early evidence for Earth’s ocean and the onset of continental crust formation. The study was published on PNAS.