The oldest piece of Earth
A crystal barely wider than a hair survives 4.4 billion years — the oldest terrestrial material known.
- When
- Known to
- ± 8 million years
- Era
- Hadean
A zircon grain from the Jack Hills of Western Australia dates to 4,404 ± 8 million years, formed only about 160 million years after the planet itself. Zircon is almost indestructible and traps uranium while excluding lead, making it an exceptional clock. Its oxygen isotopes indicate it crystallised from magma that had interacted with liquid water — the earliest evidence that Earth had a surface cool enough for oceans.