Una fetta del meteorite di El Ali, ora nella collezione di meteoriti dell’Università di Alberta, contiene due minerali mai visti prima sulla Terra. Credito: Università di Alberta
Nuovi minerali scoperti in un enorme meteorite potrebbero rivelare indizi sulla formazione di asteroidi.
Un team di ricercatori ha scoperto almeno due nuovi minerali mai visti prima sulla Terra in un meteorite di 33.000 libbre (15.000 kg) trovato in Somalia nel 2020. Questo meteorite gigante è il nono più grande mai trovato.
“Quando trovi un nuovo minerale, significa che le effettive condizioni geologiche, la chimica delle rocce, erano diverse da quelle che erano state trovate prima”, afferma Chris Hurd, professore presso il Dipartimento di Scienze della Terra e dell’Atmosfera e curatore del meteorite dell’Alberta collezione. “Questo è ciò che lo rende eccitante: in questo particolare meteorite ci sono due minerali descritti ufficialmente che sono nuovi per la scienza”.
Una fetta di 70 grammi del meteorite è stata inviata all’Università di Alberta per la classificazione, dove sono stati scoperti i due minerali. Sembra che ci sia già un possibile terzo minerale allo studio. Hurd osserva che se i ricercatori ottengono più campioni dal massiccio meteorite, c’è la possibilità che trovino più minerali.
I due minerali appena scoperti sono stati chiamati elaliite ed elkinstantonite. Il primo nome, elaliite, deriva dal meteorite stesso, che ufficialmente si chiama “Il più altoUn meteorite perché è stato trovato vicino alla città di Al-Ali nella regione di Hiran in Somalia. Flock ha definito l’elkenstantonite il secondo minerale dopo Lindy Elkins-Tanton, vicepresidente della Planetary Initiative presso l’Arizona State University, professore al College of Earth and Space Exploration dell’ASU e ricercatore principale per[{” attribute=””>NASA’s upcoming Psyche mission.
A slice of the El Ali meteorite contains two minerals never before seen on Earth. Credit: University of Alberta
“Lindy has done a lot of work on how the cores of planets form, how these iron-nickel cores form, and the closest analogue we have are iron meteorites. So it made sense to name a mineral after her and recognize her contributions to science,” Herd explains.
In collaboration with researchers at the University of California, Los Angeles (UCLA) and the California Institute of Technology (Caltech), Herd classified the El Ali meteorite as an “Iron, IAB complex” meteorite, one of over 350 in that particular category.
As Herd was analyzing the meteorite to classify it, he saw something that caught his attention. He brought in the expertise of Andrew Locock, head of the University of Alberta’s Electron Microprobe Laboratory, who has been involved in other new mineral descriptions including Heamanite-(Ce).
“The very first day he did some analyses, he said, ‘You’ve got at least two new minerals in there,’” says Herd. “That was phenomenal. Most of the time it takes a lot more work than that to say there’s a new mineral.”
Locock’s rapid identification was possible because the two minerals had been synthetically created before, so he was able to match the composition of the newly discovered natural minerals with their human-made counterparts.
Scientists are still examining the minerals in detail to determine what they can tell us about the conditions in the meteorite when it formed.
“That’s my expertise — how you tease out the geologic processes and the geologic history of the asteroid this rock was once part of,” says Herd. “I never thought I’d be involved in describing brand new minerals just by virtue of working on a meteorite.”
Herd also notes that any new mineral discoveries could possibly yield exciting new uses down the line.
“Whenever there’s a new material that’s known, material scientists are interested too because of the potential uses in a wide range of things in society.”
While the future of the meteorite remains uncertain, Herd says the researchers have received news that it appears to have been moved to China in search of a potential buyer. It remains to be seen whether additional samples will be available for scientific purposes.
Herd described the findings at the Space Exploration Symposium on November 21 at the University of Alberta’s ETLC Solarium.
