Oxidation of Pyrite Grains: A Mössbauer Spectroscopy and Mineral Magnetism Study
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Abstract
Fe2+ in pyrite is found in a low-spin d6 configuration, a necessary condition for diamagnetic and semi-conducting properties of material. The semi-conducting property of pyrite has been studied since the time when pyrite was used as a rectifier in early radios. Pyrite posses the highest possible crystal field stabilisation energy and offers a better altemative as solar material compared to Si-based materials. Unfortunately, pyrite is difficult to study due to its inherent deviation from stoichiometry and its ease of oxidation. Since pyrite and its oxidation products are all Fe-bearing phases, combining Mössbauer spectroscopy with mineral magnetic methods provides enough information to monitor the oxidation of pyrite in air and identify the different phases produced and their relation to different experimental parameters. For mm-sized grain samples, heating FeS2 at temperatures between 450 °C and 650 °C five different mineral assemblages are identified. FeS2 is oxidized to α-Fe2O3 along two separate routes:
$${\text{FeS}}_{2} \to {\text{FeSO}}_{4} \to \varepsilon {\text{ - Fe}}_{2} {\text{O}}_{3} \to \alpha {\text{ - Fe}}_{2} {\text{O}}_{3} ;\;{\text{and}}$$
$${\text{FeS}}_{2} \to {\text{FeSO}}_{4} \to {\text{Fe}}_{2} {\left( {{\text{SO}}4} \right)}_{3} \to \beta {\text{ - Fe}}_{2} {\text{O}}_{3} \to \alpha {\text{ - Fe}}_{2} {\text{O}}_{3} $$
Key Words
hysteresis magnetization Mössbauer spectroscopy pyrite susceptibilityPreview
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References
- 1.Briggs D. E. G., Raiswell R., Botrell S. H., Hatfield D. and Bartels C., Am. J. Sci. 295 (1995), 282.CrossRefGoogle Scholar
- 2.Brotzen F., Sveriges Geologiska Undersökning Avhandlingar och Uppsatser Serie C 570 (1959), 81.Google Scholar
- 3.Cheetham A. H., Smithson. Contrib. Paleobiol. 6 (1971), 87.Google Scholar
- 4.Holland B. SGU Ser. C (1982), 95.Google Scholar
- 5.Ferrow E. A., Kalinowski B. E., Veblen D. R. and Schweda P., Eur. J. Mineral. 11 (1999), 999.Google Scholar
- 6.Orlický O., Geologica Carpathica 45 (1994), 113.Google Scholar
- 7.Zboril R., Mashlan M. and Petridis D., Chem. Mater. 14 (2002), 969.CrossRefGoogle Scholar
- 8.Dunn J. G., Thermochim. Acta 300 (1997), 127.CrossRefGoogle Scholar
- 9.O’Reilly W., Rock and Mineral Magnetism, Blackie, Glasgow and London, 1984, p. 220.Google Scholar
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© Springer Science+Business Media, Inc. 2006