An iron-poor type known as aubrite is a better fit (see the box on page 31).
But a piece of Mercury should be much darker than an aubrite. It might also smell faintly of sulfur, appear heavily shocked, exhibit signifi cant exposure to cosmic rays, and even be slightly magnetic.
All previous candidates for pieces of Mercury (called angrites and aubrites; S&T: April 2012, page 31) are close but imperfect matches to the surface composition found by NASA's Messenger spacecraft.
"NWA 7325 is tantalizing, and certainly more consistent with the Messenger results than either angrites or aubrites," he explains, "but we need a [spacecraftreturned sample] for 'ground truth'."
We have not yet identified any other parent asteroids with as much certainty, but we know from their composition that the
Aubrites and the Ureilite meteorites are rocks from the mantles of two different asteroids that had violently explosive eruptions, which ejected what should have become their crustal rocks into space at escape velocity.