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Science 5 October 1990:
Vol. 250. no. 4977, pp. 111 - 113
DOI: 10.1126/science.250.4977.111
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Articles

Hematite Nanospheres of Possible Colloidal Origin from a Precambrian Banded Iron Formation

Jung Ho Ahn 1 and Peter R. Buseck 2

1 Department of Geology, Arizona State University, Tempe, Arizona, 85287-1404
2 Departments of Geology and Chemistry, Arizona State University, Tempe, Arizona 85287-1404

Exceptionally small spheres (nanospheres) of hematite (diameters between 120 and 200 nanometers) occur in the Marra Mamba Iron Formation of the Hamersley Basin, Australia. The nanospheres are clustered into small aggregates and may have formed by structural ordering and dehydration of colloidal iron hydroxide particles. Individual spheres consist of numerous thin, curved hematite platelets surrounding a central void that is approximately half the diamter of the sphere; this texture suggests that they formed by a volume reduction of the original colloidal particles by sim12.5%. The occurrence of hematite nanospheres supports the hypothesis that some ofthe iron was deposited colloidally during the development ofbanded iron formations, approximately 2.5 billion years ago.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Chemical and biological evolution of early Earth: Constraints from banded iron formations.
H. Ohmoto, Y. Watanabe, K. E. Yamaguchi, H. Naraoka, M. Haruna, T. Kakegawa, K.-i. Hayashi, and Y. Kato (2006)
Geological Society of America Memoirs 198, 291-331
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Metastable Si-Fe phases in hydrothermal sediments of Atlantis II Deep, Red Sea.
N. TAITEL-GOLDMAN and A. SINGER (2002)
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Biogenic Magnetite Formation through Anaerobic Biooxidation of Fe(II).
S. K. Chaudhuri, J. G. Lack, and J. D. Coates (2001)
Appl. Envir. Microbiol. 67, 2844-2848
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Fractionation of manganese from iron in Archaean and Proterozoic sedimentary ores.
G.P. Glasby (1997)
Geological Society, London, Special Publications 119, 29-42
   Abstract »    PDF »
Mineralogy and geochemistry of Archaean greenstone belt-hosted Mn formations and deposits of the Dharwar Craton: Redox potential of proto-oceans.
C. Manikyamba and S.M. Naqvi (1997)
Geological Society, London, Special Publications 119, 91-103
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