Oldest igneous rock found on Earth
Who
Erg Chech 002
Where
Algeria ()
When

The oldest igneous (aka magmatic) rock discovered on Earth is a c. 4.565-billion-year-old meteorite that was found in the desert of south-west Algeria in May 2020. Named Erg Chech 002 (abbreviated to EC 002), it is a stony meteorite known as an achondrite, formed from a type of volcanic rock known as andesite. The meteorite is marginally older than Earth, which formed c. 4.5 billion years ago. Scientists believe that it may have originated in the crust of a protoplanet – a celestial body born just a few million years after the Solar System itself coalesced. It is therefore hoped that study of EC 002 may reveal more about the conditions that existed in the young Solar System. A paper detailing the dating process of the meteorite was published in the journal Proceedings of the National Academy of Sciences on 16 March 2021.


Only a few thousand known meteorites are volcanic in nature, and of those EC 002 represents an even rarer type: it is composed of andesite rock, rather than basaltic rock. Andesite rock comprises mostly sodium-rich silicates; basaltic rock, by contrast, is rich in magnesium and iron. Here on Earth, andesite is generally found near subduction zones – regions where tectonic plates have collided and one has been pushed beneath the other.

The meteorite was discovered in a sand sea known as Erg Chech, hence its name.

It is rare to find such ancient rocks on Earth, as plate tectonics have continuously recycled the planet’s crust. To put the discovery in context, the oldest rock formed on Earth – samples of bedrock from the Nuvvuagittuq greenstone belt on the eastern shore of Hudson Bay in Canada – is c. 4.28 billion years old.

The oldest suspected Earth rock found on the Moon is a 4.011-billion-year old chunk of felsite that was collected during the Apollo 14 mission in 1971. Scientists believe that it was blasted off Earth’s surface and onto the Moon after a huge impact event.

The research on the meteorite was a collaborative study between the Université de Bretagne Occidentale, the Université de Paris, L'Institut de planétologie et d'astrophysique de Grenoble and Université de Lorraine (all France) and the National Institute of Polar Research (Japan), led by Professor Jean-Alix Barrat at the Université de Bretagne Occidentale (France).

Photo credit: Darryl Pitt / Christie’s