Iron-oxidizing bacteria feed on dissolved ferrous solutions in groundwater at the point where it emerges back into the atmosphere. There it may form deposits of ferrous oxide which can be collected and converted into yellow or red ochre pigments. This is also a historical source of what is known as bog iron.
These pigments are an important resource for many indigenous cultures, including the Wabanakiak. Ochre is a strong, persistent pigment that can last for thousands of years and has many practical and ceremonial uses. At times, the trickling iron-rich water will create intricate, organic cell-like patterns on rock or soil as the molecules aggregate. Sometimes it’s just a rainbow shimmer on the water surface.