Fossil Meteorite with Cephalopod at the Field Museum
Most of the meteorites we have to study fell out of the sky in the not too distant past. Meteorites that feel a lot time ago, geologically speaking, are really rare. That doesn't mean that rocks from space haven't fallen to Earth throughout its history, of course; in fact old meteorite impact sites are well known in the rock record. Big meteorites often vaporize on impact, and small ones weather away quite easily at Earth's surface. There are a few, however, that have been preserved in the ancient rock record as "fossil" meteorites. This one on display at the Field Museum is preserved in a Devonian limestone. The weathering rind is pretty thick, even with the alien rock encased in another stone. Some minerals in meteorites, like the spinels, are much less susceptible to weathering and last longer than the olivine, iron, and pyroxenes that dominate chondrites. This one is also special in that it also preserves a beautiful, large cephalopod, which happened to also get fossilized very near the meteorite.
#Geology #Paleontology #Meteorites #FieldMuseum #Science #Nature #PostMoreRocks