Clays and Clay Minerals

, Volume 35, Issue 1, pp 29–37 | Cite as

Noncrystalline Fe-Si-Al-Oxyhydroxides

  • Richard A. Eggleton


High-resolution transmission electron microscopy of noncrystalline Fe-Si-Al-oxyhydroxide gels shows a common structure of hollow packed spheres having external diameters ranging from 50 to 1000 Å. Some sphere walls display a concentric structure, particularly if the gel composition is close to that of a crystalline clay mineral (e.g., smectite, kaolin). The spheres probably formed by expansion of void space (bubbles) as the surrounding gel contracted 5–10% because of partial ordering of the Fe-Si-Al-oxygen network. Much of the water contained in such noncrystalline minerals is incorporated within the bubbles.

Key Words

Gels High-resolution transmission electron microscopy Iron Morphology Noncrystalline oxyhydroxides 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Banfield, J. F. (1985) Mineralogy and chemistry of granite weathering: M.Sc. thesis, Australian National University, Australia, 229 pp.Google Scholar
  2. Chukhrov, F. W., Zvyagin, B. B., Ermilova, L. P., and Gorshkov, A. I. (1973) New data on iron oxides in the weathering zone: in Proc. Int. Clay Conf., Madrid, 1972, J. M. Serratosa, ed., Div. Ciencas C.S.I.C., Madrid, 333–341.Google Scholar
  3. Colman, S. M. (1982) Chemical weathering of basalts and andesites: Evidence from weathering rinds: U.S. Geol. Surv. Prof. Pap. 1246, 51 pp.Google Scholar
  4. Eggleton, R. A. and Buseck, D. R. (1980) High-resolution electron microscopy of feldspar weathering: Clays & Clay Minerals 28, 173–178.CrossRefGoogle Scholar
  5. Eggleton, R. A. and Keller, J. (1982) The palagonitisation of limburgite glass—a TEM study: N. Jb. Miner. Mh. Jg. 1982, 321–336.Google Scholar
  6. Eggleton, R. A., Pennington, T. H., Freeman, R. S., and Threadgold, I. M. (1983) Structural aspects of the hisingerite-neotocite series: Clay Miner. 18, 21–31.CrossRefGoogle Scholar
  7. Eitel, W. (1964) Silicate Science VI: Silicate Structures: Academic Press, New York, 666 pp.Google Scholar
  8. Henderson, P. (1982) Inorganic Geochemistry: Pergamon Press, New York, 353 pp.Google Scholar
  9. Henmi, T. and Wada, K. (1976) Morphology and composition of allophane: Amer. Mineral. 61, 379–390.Google Scholar
  10. Ildefonse, P. (1978) Mécanismes de l’altération d’une roche gabbroïque du Massif du Pallet (Loire Atlantique): Doctorat Thèse, Université de Poitiers, Poitiers, France, 142 pp.Google Scholar
  11. Kirkman, J. H. (1977) Possible structure of halloysite disks and cylinders observed in some New Zealand rhyolitic tephras: Clay Miner. 12, 199–216.CrossRefGoogle Scholar
  12. Kirkpatrick, R. J. (1983) Theory of nucleation in silicate melts: Amer. Mineral. 68, 66–67.Google Scholar
  13. Parfitt, R. L. (1980) Chemical properties of variably charged soils: in Soils with Variable Charge, B. K. G. Theng, ed., Soil Bureau D.S.I.R., Lower Hutt, New Zealand, 167–194.Google Scholar
  14. Parfitt, R. L. and Henmi, T. (1980) Structure of some al-lophanes from New Zealand: Clays & Clay Minerals 28, 285–294.CrossRefGoogle Scholar
  15. Phillips, J. C. (1982) Spectroscopic and morphological structure of tetrahedral oxide glasses: Solid State Physics 37, 93 pp.Google Scholar
  16. Shayan, A. (1984) Hisingerite material from a basalt quarry near Geelong, Victoria, Australia: Clays & Clay Minerals 32, 272–278.CrossRefGoogle Scholar
  17. Sudo, T., Shimoda, S., Yotsumoto, H., and Aita, S. (1981) Electron Micrographs of Clay Minerals: Elsevier, Amsterdam, 203 pp.Google Scholar
  18. Tazaki, K. (1982) Analytical electron microscopical studies of halloysite formation processes—morphology and composition of halloysite: in Proc. Int. Clay Conf, Bologna, Pavia, 1981, H. van Olphen and F. Veniale, eds., Elsevier, Amsterdam, 573–584.Google Scholar
  19. Wada, K. (1982) Amorphous/clay minerals—chemical composition, crystalline state, synthesis, and surface properties: in Proc. Int. Clay Conf, Bologna, Pavia, 1981, H. van Olphen and F. Veniale, eds., Elsevier, Amsterdam, 385–398.Google Scholar
  20. Wada, S.-I. and Wada, K. (1977) Density and structure of allophane: Clay Miner. 12, p. 289.CrossRefGoogle Scholar
  21. Webb, J. A. and Finlayson, B. L. (1984) Allophane and opal speleothems from granite caves in southeast Queensland: Aust. J. Earth Sci. 31, 341–349.CrossRefGoogle Scholar

Copyright information

© The Clay Minerals Society 1987

Authors and Affiliations

  • Richard A. Eggleton
    • 1
  1. 1.Department of GeologyAustralian National UniversityCanberraAustralia

Personalised recommendations