Pallasites: Stony-Iron Meteorites

Pallasites are one of several types of meteorites that are made of roughly equal amounts of metal and rock. Pallasites consists of large olivine grains (green or brown) set in a matrix of iron-nickel metal. They are the rarests of all meteorites, constituting only about 1% of the total.


The photo above is a cut and polished slice of the Brahin pallasite. The photo below shows a cut and polished slice of the Esquel pallasite.

Iron meteorites represent the frozen and shattered cores of protoplanets. Many achondrites represent fragments of the mantles of these same protoplanets. How do pallasites fit in? Pallasites are thought to have formed at the boundary between the core and mantle in these long-gone protoplanets. The Earth's mantle, for example, is rich in the mineral olivine (the brownish/greenish minerals above) and tiny olivine crystals are one of the dominant minerals in many stony meteorites. So, it is reasonable to assume that these most attractive of meteorites happened to have formed at a very interesting boundary in some ancient doomed protoplanets.

Image credits: Meteorites.com

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