13415B (Acapulcoite)

Classification led by Jen Mitchell

This meteorite belongs to Monash University, Melbourne, Australia

This meteorite will possibly receive an official name of 'Watson ***' - to be confirmed by the Nomenclature Committee of the Meteoritical Society.

The type specimen (34 g) will be on deposit at the University of Monash, Australia

Our First Acapulcoite

Around 85% of meteorites are chondrites, so finding an achondrite is even more exciting than usual. 13415B is a type of primitive achondrite called an acapulcoite, and is the first one that we've classified.

Primitive achondrites record the first stages of igneous activity in the Solar System, so they are very similar in composition to chondrites. More evolved achondrites like the HEDs and Martians have very different mineral compositions from these early rocks.

Acapulcoites are made from olivine, pyroxene, plagioclase feldspar, and a range of iron metals and sulphides. They are very similar to another group of primitive achondrites called lodranites, but acapulcoites have much smaller crystal sizes - often less than 0.5mm!

There isn't a known parent body for this type of meteorite, so there's a good chance that it was completely destroyed in the early Solar System. That means that researchers have to use the less than 100 classified acapulcoites to try and unravel their history and understand what they can tell us about planetary formation.

A backscattered electron (BSE) image of 13415B. Dark grey = olivine, pyroxene; light grey-white = metal and sulphides.