It’s called Erg Chech 002 (or EC 002 for short) and it was discovered in 2020 in the Sahara desert . It is a very special rock because it is even older than Earth itself. Analysis of the many fragments of this space rock suggests that they solidified millions of years before our planet was formed, which gives us clues as to what the beginning of planetary formation must have been like.
The meteorite in question weighs about 32 kilos and the team, which publishes its findings in the journal PNAS, has estimated the age of the space fragments to be 4.565 million years, some 20 million years older than our own planet and more. older than the previous record holder dated to 1 million years. When this rock formed, the solar system was barely 2 million years old, and according to the survey, it took at least 100,000 years to cool and solidify after it had melted. It is the oldest evidence we now have to help us understand the basic components of the planets.
It is a type of andesite rock that, on Earth, is mainly found in subduction zones (areas where tectonic plates have collided and one has been pushed under the other) and we can rarely see it in meteorites. Most of the meteorites discovered on Earth are made of another type of volcanic rock called basalt.
The experts’ conclusion is that this EC 002 was probably part of the crust of an ancient protoplanet that broke apart early in the solar system. Of the 10,000 objects in the Sloan Digital Sky Survey database, no known asteroid looks like EC 002.
“As you get closer to the beginning of the solar system, it is increasingly difficult to obtain samples,” says Jean-Alix Barrat, leader of the work. “We probably won’t find another sample older than this one.”
Composed of mostly volcanic rock, scientists determined that the rock was sometime liquid lava that cooled, solidified, and finally formed this 30-kilogram piece that reached our planet.
Considering that the EC 002 meteorite is made mainly of volcanic rock, it makes it rich in sodium, iron and magnesium, hence we can say that it is also the oldest magnetic rock ever observed.
How do scientists determine the age of a meteorite?
In this case, by studying the rock’s magnesium and aluminum isotopes, which showed that it was formed about 4.566 million years ago, while the Earth is 4.543 million years old. The rock, described as relatively coarse-grained, tan and beige, is stained with yellow and green chunks. It also has 58% silicon dioxide, which makes it even rarer than other meteorites previously found on Earth, since this mineral is commonly found in the volcanic regions of our planet.
“Protoplanets covered by andesitic crusts were probably frequent,” the experts clarify. “However, no asteroids share the spectral characteristics of EC 002, indicating that almost all of these bodies have disappeared, either because they became the building blocks of larger bodies or planets or were simply destroyed.”
Researchers will take a closer look at this magmatic rock, and while it opens the door to new mysteries, it will also offer new answers to the history of our solar system.
Referencia: Jean-Alix Barrat et al. A 4,565-My-old andesite from an extinct chondritic protoplanet, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2026129118
