Weighing just a bit more than 100 g, this is the largest fragment of the meteorite NWA 7325. Note the amazing light-green color of its fusion crust — one of many characteristics hinting that it might be from the planet Mercury. The cube at right is 1 cm square. Click here for a larger view.
Stefan Ralew / sr-meteorites.de
Recently studied and classified as NWA 7325 this meteorite is unlike any other in the world's
inventory. I have never seen such a strange looking specimen and it is clear why - it is the first
meteorite to be studied that has a near perfect match to the composition of the planet Mercury as
observed by NASA's MESSENGER spacecraft in orbit around Mercury.
One of MESSENGER's primary mission objectives was to determine the composition of the surface of
Mercury. NWA 7325 is the closest match we have so far but there are still differences. Those may be
explained if NWA 7325 was formed deep below the surface of Mercury and then blasted off the
planet due to a large impact - certainly plausible.
More studies need to be done but 100% confirmation may be elusive until if and when we ever get a
return sample from Mercury. We had samples of the Moon and Mars in our meteorite inventory but we
couldn't confirm their origin conclusively until we landed on the Moon and Mars, and got lunar
samples as well.
NWA 7325 may remain in origin-limbo for awhile but scientists are hopeful that further studies
with MESSENGER data applied to the space rock will provide an answer.