Oldest Dated Rocks: Includes rocks over 4 billion years old from the Hadean Eon

1. There are early rocks recovered from the Moon. This is relevant because the Moon was once part of the Earth: see giant impact hypothesis. During Apollo 16, Lunar sample 67215, dated at 4.46 billion years, was brought back. Lunar sample 67215 is the oldest known rock on Earth, even though it came from the Moon.

2. The oldest material of terrestrial origin that has been dated is a zircon mineral 4.404 ±0.008 billion years old. It was in the Jack Hills of Western Australia. The oldest consistently-dated zircon is closer to 4.35 billion years ago.

3. The oldest rock formation on Earth may be the Acasta Gneiss in the Canadian Shield in the Northwest Territories, Canada. It is composed of the Archaean igneous and gneissic cores of ancient mountain chains that have been exposed by glacial action. Again it was dated by analysis of zircons in the rocks.