Scientists may have just found the oldest intact Earth rock—on the moon. A study published Thursday in Earth and Planetary Science Lettersmakes the case that one of the rocks collected by Apollo 14 astronauts in 1971 contains a fragment of Earth’s ancient crust, dating back more than 4.011 billion years.
It’s possible that the fragment formed in a weirdly water-rich pocket of magma deep within the ancient moon. But the study authors think it’s likelier that the rock formed within our planet’s crust and got jettisoned to the moon by one of the many meteor impacts that bombarded early Earth.
Apollo 14 astronaut Alan Shepard took this photograph of the rock known as 14321 minutes before he collected it from the lunar surface.
If so, the fragment is one of the oldest Earth rocks ever found. The oldest minerals found on Earth come from Australia’s Jack Hills and are up to 4.4 billion years old. But those dates have been disputed, and even if the minerals really are that old, they’re debris left over from rocks that disintegrated long ago. By contrast, the Apollo 14 fragment is much more fully preserved.
An arrow marks the light-colored portion, or felsite clast, of 14321 that researchers think formed on Earth.
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