The oxidation of Fe in riebeckite at 0.7&thinsp;GPa

Della Ventura, Giancarlo; Oberti, Roberta; Misiti, Valeria; Radica, Francesco; Redhammer, Gunther J.; Bernardini, Simone; Boiocchi, Massimo; Mihailova, Boriana

doi:https://doi.org/10.5194/ejm-37-535-2025

Articles | Volume 37, issue 4

https://doi.org/10.5194/ejm-37-535-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

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https://doi.org/10.5194/ejm-37-535-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 37, issue 4

Research article

|

01 Aug 2025

Research article |

| 01 Aug 2025

The oxidation of Fe in riebeckite at 0.7 GPa

Giancarlo Della Ventura, Roberta Oberti, Valeria Misiti, Francesco Radica, Gunther J. Redhammer, Simone Bernardini, Massimo Boiocchi, and Boriana Mihailova

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Latest update: 01 Aug 2025

Short summary

The thermal reaction Fe²⁺ + OH^- → Fe³⁺ + O^2- +e^- + H⁺ in hydrous silicates has tremendous implications in planetary-scale phenomena like electrical anomalies, water cycling, seismicity, volcanism, and ore generation. We annealed riebeckite crystals up to 750 °C and P = 0.7 GPa and show that the amphibole stability is extended without any Fe oxidation, implying that thermally activated electron hopping contributes to the electrical conductivity of lithospheric rocks during subduction.