Where are the “missing” olivine meteorites?
Why have no meteorites been found from an asteroid's olivine mantle? Here are a few theories:
No pieces of an asteroid mantle happened to land on Earth. But considering that thousands of meteorites provide numerous samples of crusts and cores, it is hard to explain why not one single piece of mantle would have reached us.
After pieces of the crust were knocked off, the olivine mantles eroded away, pounded into dust by numerous collisions over billions of years. But other meteorites made of material just as fragile as olivine have managed to reach Earth.
A thick layer of olivine simply does not exist inside asteroids. Perhaps the olivine in differentiated asteroids did not fully separate from the crust. Or perhaps metal from the core remained mixed with olivine, and the bulk of the mantle is composed of the mixture found in pallasites.
This mystery is likely to remain unsolved until a spacecraft lands on an asteroid and analyzes its interior.
Topic: Earth Science
Keywords: Meteorites, Astrophysics, Olivine, Astrogeology, Asteroids