This is one of the oldest things I have ever seen – and that’s saying something. I’m used to thinking in terms of deep time – I’m a geologist with a deep interest in the life recorded in the rocks I’m looking at.
This, though, takes the cake in terms of its age; it's roughly two billion, six hundred million(!) years old.
As the title of this post suggests, it's rock from a banded iron formation, laid down as new-fangled oxygen released by early photosynthetic bacteria combined with iron in seawater to form iron oxides - which promptly sank, and were trapped between layers of sediments that were rick in silica. The times they were a-changing; this was part of a hugely import thing, The Great Oxygenation Event. Not only were new (and interesting!) minerals formed, but new life forms were appearing. If you want to see this gorgeous rock for yourself, it's in the Hintze Hall at London's Natural History Museum. I really do like the specimens they've got in the big alcoves these days; I think that this and the Mantellisaurus are the standout ones for me.
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