Smithsonian National Museum of Natural History
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Banded iron formation

Catalog number 76079, a cut and polished banded iron formation, from the Mineral Sciences collections at the Smithsonian Institution National Museum of Natural History. ??From the Sant Ocean Hall exhibition label: On land, red beds (iron oxide deposits) form only if the atmosphere contains free oxygen. This rock, about 2.2 billion years old, tells us that the atmosphere had at least some oxygen. Many scientists think atmospheric oxygen levels then were about 1 percent today's levels.
Photo by Chip Clark. Click to zoom.
Catalog Number NMNH 76079
Locality Minnesota, United States

On land, red beds (iron oxide deposits) form only if the atmosphere contains free oxygen. This rock, about 2.2 billion years old, tells us that the atmosphere had at least some oxygen. Many scientists think atmospheric oxygen levels then were about 1 percent today’s levels.


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