Ancient Andesite Meteorite Covered With Crystals Provides New Insights About the Evolution of the Solar System

In May 2020, a meteorite crash-landed in the dune-filled Sahara Desert in southern Algeria. The fragments of space rocks were found in the Erg Chech sand sea and contain distinctive greenish crystals.

Crystal-Studded Space Rock

Scientists officially documented 43 fragments, and according to geochemist Jean-Alix Barrat from France's Brest University, the meteorite had remained undisturbed for at least 100 years. Upon close inspection, the unusual rocks turned out to be from outer space and were part of the lumps of billion-year-old debris left from the early Solar System.

The lumps of rubble were pieces of a meteorite known as Erg Chech 002, an ancient andesite meteorite considered the oldest volcanic rock ever found. It was believed that this space rock had melted long ago in the fires of an ancient protoplanet.

In new research conducted by experts, the lead and uranium isotopes in Erg Chech 002 were analyzed, which reveals that it is almost 4.56556 billion years old. This is one of the most precise calculations made for an object from outer space, and the results question the traditional beliefs about the early stage of the Solar System.

A More Precise Calculation of Erg Chech 002

It was estimated that around 4.567 years ago, the Solar System was created from a vast cloud of dust and gas. One of the elements present in this cloud was aluminum, which existed in two forms: the stable aluminum-27 and the radioactive aluminum-27. The latter is an isotope produced from the explosion of stars and decays over time into magnesium-26.

Aluminum-26 is a beneficial particle for scientists who try to understand the formation and development of the Solar System. Since it decays over time, it can be used in dating events, especially within the first four or five million years of the Solar System's life.

The decay of aluminum-26 is also significant because it was believed to be the main heat source in the early stage of our star system. This decay affected the melting of small, ancient rocks clustered together to form the planets.

In using aluminum-26, however, experts need to know whether it was evenly spread or clumped together more densely in some places. This requires a more precise calculation of the absolute ages of some primitive space rocks. It cannot be made possible by looking at aluminum-26 alone because it quickly decays relatively after around 705,000 years. It is only helpful in determining the relative ages of various objects but not their absolute age in years.

Fortunately, scientists can make some headway if aluminum-26 is combined with data about uranium and lead. Two important isotopes of uranium, uranium-235, and uranium-238, decay into lead-207 and lead-206, respectively. Since uranium isotopes have longer half-lives, they can be used to determine the timeline of historical events directly.

In the recent study of Erg Chech 002, scientists discovered that this meteorite contains a high amount of lead-206 and lead-207, in addition to a large abundance of undecayed uranium-238 and uranium-235. The measurement of the ratios of all the lead and uranium isotopes helped the researchers estimate the age of the space with unprecedented accuracy.

The result of the study shows that aluminum-26 was quite unevenly distributed throughout the cloud of gas and dust that formed the Solar System. This contributes to a better understanding of the earliest developmental stages of our star system and the geological history of developing planets.