We May Have Found Earth's Oldest Known Rock. It Was on The Moon

MICHELLE STARR 25 JAN 2019

Earth's oldest known rock may have been found, in the last place anyone would have thought to look for it: in samples of rock from the Moon, brought back home to Earth by Apollo 14 astronauts in 1971.

We're not talking about a "Moon was once part of Earth" rock (that's just one hypothesis for the Moon's origin, anyway).

Nope. According to an international team of scientists, there's evidence the rock was terrestrial in origin - it's a 2-gram piece of quartz, feldspar, and zircon embedded in a larger chunk of rock called Big Bertha - minerals that are rare on the Moon, but really common here on Earth.

And chemical analysis has revealed that it formed in an oxidised system like Earth's, in Earth-like temperatures, rather than the Moon's temperature conditions. If it had formed on the Moon, that would require conditions never before inferred from lunar samples.

More:
https://www.sciencealert.com/earth-s-oldest-rock-may-have-been-found-it-was-um-on-the-moon