The world's oldest crystal:
To determine the age of the zircon fragment, the scientists first used a widely accepted dating technique based on determining the radioactive decay of uranium to lead in a mineral sample.Now there really is something older than dirt...
But because some scientists hypothesized that this technique might give a false date due to possible movement of lead atoms within the crystal over time, the researchers turned to a second sophisticated method to verify the finding.
They used a technique known as atom-probe tomography that was able to identify individual atoms of lead in the crystal and determine their mass, and confirmed that the zircon was indeed 4.4 billion years old.
To put that age in perspective, the Earth itself formed 4.5 billion years ago as a ball of molten rock, meaning that its crust formed relatively soon thereafter, 100 million years later. The age of the crystal also means that the crust appeared just 160 million years after the very formation of the solar system.