Banded Iron Formation

Banded iron formations are among the oldest and most important geological specimens on Earth, formed during the Precambrian era nearly three billion years ago. These intricately layered stones preserve evidence of one of the most significant events in the history of the planet: the emergence of early life and the gradual oxygenation of Earth's oceans and atmosphere.

These formations originated in Earth's ancient oceans, where simple single-celled organisms began producing oxygen through photosynthesis. This oxygen reacted with dissolved iron in seawater, causing iron oxides to precipitate and settle on the ocean floor in successive layers over an immense span of time. Over hundreds of millions of years, geological processes transformed these deposits into the richly colored material seen here.

This example was recovered near Port Hedland in Western Australia, a region where many of the finest and most visually striking banded iron formations are found, and is composed of swirling bands of crimson jasper, metallic hematite, and shimmering tiger's eye.

REFERENCES:

“Banded Iron Formation.” The Australian Museum