At 2.5 billion years old and weighing in at 2.5 tonnes, the banded iron formation is so heavy that Museum engineers had to reinforce the floor underneath it in Hintze Hall. 'The rock tells a ...

Figure A shows a banded iron formation. These structures were formed from 2.5 billion years to 1.8 billion years ago. Figure B shows a stromatolite. Stromatolites were first formed 3.5 billion years ...