It's been a long while, but I've saved up and recently added a few new meteorites to the collection. I'm very excited about these ones!
First is a piece of lunar meteorite NWA 11474.
Yes, this is a rock from the Moon
, with a fascinating history.
It is a breccia, or a mixture of broken fragments that have been compactified into a new rock, like the lunar form of a terrestrial conglomerate. On the Moon, the constant bombardment of meteorites breaks up and throws rocks around, so any particular location on the Moon has a regolith made up of rock fragments of all different sizes that came from all over. Finally some mildly larger impact, perhaps creating a crater a few kilometers across, launched some of these rocks away from the Moon entirely and into an orbit around Earth, perhaps remaining in orbit for a few tens of thousands to millions of years, before landing on Earth. Most lunar meteorites are discovered in Antarctica, or in this case in northwest Africa (hence the NWA designation).
There are also a few ways to tell (besides a geochemical analysis) that this is a Moon rock and not some terrestrial rock. The fragments within terrestrial conglomerates tend to be rounded, if they were formed in rivers. They also tend to be of similar size and compositions. The fragments in a lunar breccia on the other hand are never round, and have a fractal distribution of sizes. If you zoom in on a part of one, it will look much the same.
Some more neat info and images of lunar meteorites, with comparisons to rocks in the Apollo sample, here
Next is Martian meteorite
NWA 11288. (Label says 407 grams, which was the whole meteorite, while this piece is 140mg.)
Last, a slice of an iron meteorite, Muonionalusta
, displaying the octahedral Widmanstätten pattern.