Rock sample from a banded iron formation (BIF). Moodies Group, Barberton Greenstone Belt, South Africa. The group is dated at 3.15 Ga (billion years old). Scalebar is in cm. Sample courtesy: K. Lehmann and prof. J.D. Kramers
<a href="//commons.wikimedia.org/wiki/User:Woudloper" title="User:Woudloper">Woudloper</a>
CC BY-SA 1.0
<span class="int-own-work" lang="en">Own work</span>