Discover the fascinating North West Africa (NWA) 12774, an Angrite meteorite found in the Sahara Desert of Mauritania. This rare fragment offers compelling evidence that large planetary bodies were formed and subsequently destroyed during the chaotic early years of our solar system.
Artist’s impression of the protoplanetary disk surrounding HD 107146. Image credit: A. Angelich / NRAO / AUI / NSF.
“It’s hard to believe that the world was once this vast,” remarked Dr. Aaron Bell, the lead author of the study.
“We know it exists because some of its fragments have landed on Earth.”
“These meteorites contain evidence of a distinct evolutionary path for early planet formation.”
In their research, Bell and colleagues studied a sample of the NWA 12774 Angrite meteorite.
“Angrites are among the oldest known volcanic rocks in the solar system, having formed within a few million years of the solar system’s inception around 4.56 billion years ago,” the researchers explained.
“They are also extremely rare; of the more than 80,000 meteorites discovered on Earth, only 68 are classified as angrite.”
“What makes angrites particularly intriguing is their unique chemistry. Unlike Earth, Mars, and other rocky planets, angrites contain very little silicon dioxide or silica, which are major components of virtually all known terrestrial planets.”
“Therefore, scientists previously believed that angrites originated from small asteroids, planets with a radius of less than 200 km (124 miles).”
However, researchers found that NWA 12774 includes clinopyroxene, a mineral typically encountered in Earth’s crust and mantle.
This clinopyroxene is notably rich in aluminum, suggesting that the rock formed under immense pressure deep within its parent body.
Scientists reconstructed the conditions necessary for NWA 12774 to form.
X-ray image of NWA 12774. Image credit: Aaron Bell / CU Boulder.
Surprisingly, the aluminum-rich clinopyroxene requires pressures of at least 17.5 kbar, which is significantly higher than the crushing pressure at the bottom of the Mariana Trench (around 1 kilobar).
This level of pressure wouldn’t be feasible within a small asteroid.
Calculations indicate that the progenitor of the Angrite must have had a radius of at least 1,000 km (621 miles).
Additional clues about the meteorite suggest even more astonishing possibilities.
The crystals in NWA 12774 retain sharp edges and distinct chemical patterns, which would have been erased if formed deep underground.
This implies that the crystals likely originated at a relatively shallow depth in a much larger parent body.
In this case, the original planet could have a radius greater than 1,800 km (1,118 miles), making it comparable in size to Earth’s moon or approaching a Mars-sized body with a radius of 3,300 km (2,050 miles).
“We have numerous understudied meteorites still in storage, indicating there may be more protoplanets yet to be discovered,” says Bell.
“It remains uncertain what led to the demise of the protoplanet. One possibility is a catastrophic event in the early solar system that shattered it, with its fragments providing materials for the formation of other terrestrial planets, including Earth.”
“The materials forming the matrix of angrites differ fundamentally from those of Earth and Mars.”
“This divergence indicates distinct evolutionary pathways in the formation of planets during the early solar system,” Dr. Bell concluded.
For more insights, check out the study published online on April 10 in the journal Earth and Planetary Science Letters.
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Aaron S. Bell et al. 2026. High-pressure clinopyroxene from Northwest Africa 12774 and new global pressure evidence for an angritic parent body the size of a planetary embryo. Earth and Planetary Science Letters 685: 120029; doi: 10.1016/j.epsl.2026.120029
Source: www.sci.news
