August 4, 2018
New Research Sheds Light On The Most Ancient Igneous Meteorite Ever Discovered

Scientists have been able to gradually piece together the formation of the solar system which they believe occurred around 4.6 billion years ago, and the latest discovery of the oldest igneous meteorite that has ever been recovered has added further details about the creation of the very early solar system.

Researchers from Arizona State University, the University of New Mexico, and NASA's Johnson Space Center have recently conducted a new study on a meteorite known as NWA 11119 that was found in Mauritania inside of a sand dune, as reports, and the color of this rock was found to be extremely light in comparison with other meteorites and had green crystals in its interior with quench melt that had formed around it.

Carl Agee, who is a professor and director at the UNM Institute of Meteoritics, observed that this igneous meteorite showed clearly that asteroids can vary in terms of their color and look, with some appearing very similar to the crust that is found on Earth.

"The age of this meteorite is the oldest, igneous meteorite ever recorded. Not only is this just an extremely unusual rock type, it's telling us that not all asteroids look the same. Some of them look almost like the crust of the Earth because they're so light colored and full of SiO2. These not only exist, but it occurred during one of the very first volcanic events to take place in the solar system."
By analyzing the igneous meteorite with CT (computed tomography) and an electron microprobe, scientists were able to learn more about the mineralogy of this rock along with its basic composition. For instance, the contents of this silica mineral-rich achondrite rock showed researchers that this particular meteorite had quite a lot in common with volcanic rocks that were created when the solar system would have been just 3.5 million-years-old.

As lead author Poorna Srinivasan has explained, scientists were shocked to find that 30 percent of the meteorite was comprised of tridymite, something which has never been seen in meteorites before, showing that the rock is more in keeping with other volcanic rocks that are found on our own planet.

"The mineralogy of this rock is a very, very different from anything that we've worked on before. I examined the mineralogy to understand all of the phases that comprise the meteorite. One of the main things we saw first were the large silica crystals of tridymite which is a similar to the mineral quartz. When we conducted further image analyses to quantify the tridymite, we found that the amount present was a staggering 30 percent of the total meteorite – this amount is unheard of in meteorites and is only found at these levels in certain volcanic rocks from the Earth."
Scientists were extremely keen to learn where this igneous meteorite had originally formed and conducted chemical and isotopic analyses on it which proved conclusively that the rock was indeed extraterrestrial. And while the source of the meteorite has still not been discovered, scientists have tentatively tied it to a couple of meteorites, according to Srinivasan.
"Based on oxygen isotopes, we know it's from an extraterrestrial source somewhere in the solar system, but we can't actually pinpoint it to a known body that has been viewed with a telescope. However, through the measured isotopic values, we were able to possibly link it to two other unusual meteorites (Northwest Africa 7235 and Almahata Sitta) suggesting that they all are from the same parent body – perhaps a large, geologically complex body that formed in the early solar system."
The new study on the oldest igneous meteorite that scientists have ever discovered has been published in the journal Nature Communications.