Banded Iron FormationCollection Highlights | Updated 1 week ago Banded iron formation from the Archean Cleaverville Formation (3020 million years old), Ord Ranges, northern Pilbara. Specimen is 2.8 m long. WA Museum specimen number R1.2016 WA Museum Take a close look at this magnificent slab of rhythmically banded iron formation (BIF) and its intricately folded layers. Notice the golden-brown tiger eye that shimmers in the light. Vast deposits of BIFs like this accumulated on the sea floor billions of years ago. Now preserved in the ancient crust of the Pilbara region, the iron ores produced from BIFs are WA’s largest export commodity and have transformed the State. This slab of BIF, from the Cleaverville Formation in the Ord Ranges of the northern Pilbara, is Archean in age, ~3020 million years old. Over 2.5 billion years ago the deep-sea floor was barren. Submarine volcanoes pumped out iron and silicon dissolved in hot seawater. Oxygen produced by early life may have changed the chemical balance of seawater, causing iron- and silicon-rich minerals to be deposited as vast quantities of mud. In a sense, the early oceans ‘rusted’, eventually producing great thicknesses of banded iron formations. Rock Collection