Meteorite Mundrabilla (pair) – Nullarbor plain, Australia

This iron meteorite was discovered in 1911 in the Nullarbor region of Australia. It is one of the largest meteorites found, weighing a total of 22 tonnes, with the largest fragment weighing 12.4 tonnes. The first piece found in 1911 weighed 112 grams, and over the next 50 years several more fragments were discovered weighing between 39 and 116 grams. It wasn't until 1966 that the two largest fragments were discovered, weighing 12.4 and 5.4 tonnes, which were about 180 metres apart.

The Mundrabilla meteorite contains 65-75% iron and nickel as well as inclusions of graphite and silicates, mainly olivine, pyroxene and plagioclase. It is classified as an IAB grade octahedrite. It is characterized by distinctive Widmanstätten patterns, which are formed during the very slow cooling of the iron-nickel metal in the core of the meteorite's parent body. These patterns appear when the surface is etched with acid and then polished to reveal a structure composed of kamacite and taenite alloys.