Wednesday November 30, 2022
By Hamdi Issawi
A sample of the El Ali meteorite found in Somalia. Scientists at the University of Alberta helped identify two new minerals while classifying the meteorite. PHOTO BY UNIVERSITY OF ALBERTA METEORITE COLLECTION /Courtesy
Scientists at the University of Alberta helped identify two new minerals in a meteorite found half a world away.
After the university received a sample of the 15-ton space rock found in Somalia, geologist Chris Herd was working to characterize and classify the meteorite, he told Postmedia in an interview. The effort is a collaboration involving the University of California in Los Angeles and the California Institute of Technology.
“At that point, I noticed some things that I couldn’t really explain,” said Herd, who’s also a professor in the university’s department of earth and atmospheric sciences.
That’s when he consulted colleague Andrew Locock, who runs the university’s electronic microprobe lab, for a more careful analysis of the meteorite’s chemistry, and quickly learned that the researchers had a discovery on their hands.
A meteorite known as ‘Nightfall’
The process of identifying a new mineral requires researchers to go through the hard work of describing the substance’s crystal structure and show that it’s distinct from anything else, but the minerals found in the meteorite had already been synthesized by a group of scientists in the 1980s, making them easier to recognize, Herd said.
“But a synthetic version is officially not a mineral,” Herd said. “A mineral has to be found in nature.”
In this case, it was a hunk of nature that fell from the stars, which warranted official names for the new minerals.
Elkinstantonite, named after Arizona State University professor Lindy Elkins-Tanton, has a blocky structure, while elaliite, named for the meteorite itself— or rather, where it was found — has a more needle-like appearance, Herd said.
Originally located in a limestone valley near El Ali, a town about 200 kilometres north of the Somali capital of Mogadishu, the meteorite (known by finders in the field as “Nightfall”) was identified in 2020, but locals in the area had knowledge of the rock dating back at least five to seven generations, The Meteoritical Society reported in a database listing for the meteorite.
“About 15 km northwest of El Ali, the camel herders knew of the rock that appeared to be metallic and used it as an anvil on which to sharpen their knives,” the listing says.
Artisanal opal miners recognized the “curious stone” in September 2019 and sent a sample to Kenya for analysis before moving it to Mogadishu about a year later, but the story of the “strange rock” spread and the government intervened as national security officers took custody of the meteorite only to release it back to the miners who warehoused it for sale, the listing says.
‘More to be done’
While the fate of the meteorite is unclear, the sample may yet have more to offer as researchers continue studying it.
“There’s more to be done here, and more indications that this meteorite is a source of other new minerals as well,” Herd said.
In the meantime, he’s asking what elkinstantonite and elaliite can reveal about the history of the meteorite.
“What we’re embarking on now is trying to figure out why these two new minerals are here in this rock, and not in other ones,” Herd said, adding that he hopes the discoveries will allow other geologists to identify these minerals in places they may have been overlooked.