Banded Iron Formations ·
Earth's First Oxygen
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.com · Fe²⁺ oxidation · cyanobacteria O₂ · rhythmic banding
Reaction
4Fe²⁺ + O₂ + 10H₂O → 4Fe(OH)₃ + 8H⁺
Peak
~2.5 Ga
phase
—
Fe²⁺ (dissolved)
O₂ from cyanobacteria
Fe³⁺ oxide (hematite)
Magnetite / chert bands
Cyanobacteria
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.com · Banded Iron Formations