Chemical Stability of FeOOH at High Pressure and Temperature, and Oxygen Recycling in Early Earth History**
Egor Koemets, Timofey Fedotenko, Saiana Khandarkhaeva, Maxim Bykov, Elena Bykova, Marcel Thielmann, Stella Chariton, Georgios Aprilis, Iuliia Koemets, Konstantin Glazyrin, Hanns‐Peter Liermann, Michael Hanfland, Eiji Ohtani, Natalia Dubrovinskaia, Catherine McCammon, Leonid Dubrovinsky
Abstract
Abstract Goethite, α‐FeOOH, is a major phase among oxidized iron species, commonly called rust. We studied the behavior of iron (III) oxyhydroxide up to 81 GPa and 2100 K using in situ synchrotron single‐crystal X‐ray diffraction. At high pressure‐temperature conditions FeOOH decomposes forming oxygen‐rich fluid and different mixed valence iron oxides (previously known phases of Fe 2 O 3 , Fe 3 O 4 , Fe 5 O 7 , and novel Fe 7 O 10 and Fe 6.32 O 9 ). Rust is known to form as a byproduct of anoxygenic prokaryote metabolism that took place massively from about 3.8 billion years (Ga) ago until the Great Oxidation Event (GOE) ∼2.2 Ga ago. Rust was buried on the ocean floor and was transported into the mantle as a consequence of plate tectonics (started ∼2.8 Ga ago). Our results suggest that recycling of rust in Earth's mantle contributes to redox conditions of the early Earth and formation of oxygen‐rich atmosphere.