Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Site Tools

  • AAAS
  • Subscribe
  • Feedback

Site Search

Search Advanced

Science 5 October 1990:
Vol. 250. no. 4977, pp. 111 - 113
DOI: 10.1126/science.250.4977.111
Prev | Table of Contents | Next

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:
Metastable Si-Fe phases in hydrothermal sediments of Atlantis II Deep, Red Sea.
N. TAITEL-GOLDMAN and A. SINGER (2002)
Clay Minerals 37, 235-248
   Abstract »    Full Text »    PDF »
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
   Abstract »    Full Text »
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
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)