An experimental study of the form of metallic iron deposited from silicate melt at a drastic fO2 decrease was conducted at 1400°C and 1 atm total pressure. The oxygen fugacity was controlled by CO/CO2 gas mixture. It was demonstrated that the metallic iron initially forms a network of euhedral crystals near the melt surface. With an increase in experimental duration, the iron loses its crystalline morphology. At a high magnification, it looks like being melted before quenching, although the experimental temperature was fixed at ca. 140°C below the melting point of pure iron. Experimental studies with similar results are reviewed.
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The author thanks I.P. Solovova (of the Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences) for help with taking microphotos of the samples and A.V. Girnis (same institute) for constructive criticism that helped the author to improve the manuscript.
Translated by E. Kurdyukov
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Borisov, A.A. Habit of Metallic Iron in Experimental Glasses: Do You Believe Your Eyes?. Petrology 29, 89–93 (2021). https://doi.org/10.1134/S0869591121010021
- metallic iron
- silicate melt
- oxygen fugacity