Meteorites are rarer than diamonds of mysterious origin

Compared to asteroids, meteorites are much smaller in size. They can burn up in Earth’s atmosphere, leaving a bright streak of light in the sky, or survive their journey and fall to the ground. There are many different types of meteorites but the most common are stony meteorites (94%). Called chondrites, they are more than 4.5 billion years old, making them the most ancient and primitive rocks in the solar system, according to the Natural History Museum. Chondrite is a material that has existed since the formation of the solar system. They are virtually unchanged compared to rocks from larger planets, which can reveal a lot of information about how the solar system came into being.

Another type of meteorite is an iron meteorite that contains a lot of iron or iron-nickel compounds, sometimes with small amounts of sulfide and carbide minerals. They originate from asteroids so large that their interiors melt under extreme pressure. Inside the asteroid, because it is denser than rock, iron often sinks to the center. In other words, these are asteroids that are on the verge of becoming planets with rocky shells and molten iron cores, similar to today’s Earth. Many of these giant asteroids later collided with other objects, ejecting chunks of rock and iron that sometimes crossed their orbits and fell to Earth.

The intersection between the above two types is stone-iron meteorites. They form with equal amounts of iron – nickel and rock minerals, creating beautiful results. Of all meteorites, pallasite is perhaps the most beautiful. They contain large olive-green crystals (a form of magnesium-iron silicate called olivine mixed in with the metal. Sometimes, olivine does not appear as single crystals but as clusters. In other specimens, they can create lattice patterns through solid metals.

Pallasite is very rare, there are only about 300 pallasite specimens out of more than 60,000 recorded meteorites. They are even rarer than diamonds, according to the UK National Space Center. Pallasite is also the most mysterious type of meteorite because today, no one knows for sure how they formed.

The process of pallasite formation is a controversial topic among scientists. Pallasite comes from many different asteroids. Those asteroids melted, separating into a layered structure of core, mantle and shell. A long-standing hypothesis is that pallasite originated at the boundary between the core and mantle, where iron from the core infiltrated the olivine in the mantle.

If so, pallasite could provide interesting information about how rocky planets like Earth formed. “We still can’t drill down to the Earth’s core, but geologists, seismologists and many other scientists can use pallasite as a model of the composition and structure of the Earth itself to understand its structure. created within it,” said Caroline Smith, director of the Earth Sciences Collection at the Natural History Museum.

However, not all experts believe in the above hypothesis. They suggest that collisions between large and small asteroids created pallasite. In the chaotic early solar system, collisions could completely disrupt planetesimals, mixing core and mantle material together.