Zebra rock is a strange patterned silt stone (siliceous argillite) unique
to the Ranford formation in the Kununurra district in the East Kimberley
region of Western Australia. The deposit is 600 million years old, placing it
in the Upper Proterozoic era or Pre-Cambrian period. It has a very fine
texture, like that of unglazed porcelain. The dark spots have the same
texture as the light areas, and are colored by Hematite (iron oxide). The
formation of the spots is mysterious, but is clearly the result of a three-dimensional
reaction-diffusion type instability. Other, more exotic explanations have been proposed.
The scale of the stripes/spots is about 1cm.
Special thanks to Sasha
Golovin for giving me this sample.
Some photos of Zebra Rock
Click on image for larger view
References and Links
- E. Mattievich, J. Chadwick, J.D. Cashion, J.F. Boas, M.J. Clark and R.D. Mackie, "Macroscopic ferronematic liquid crystals determine the structure of Kimberley Zebra Rock", proceedings of the 27th annual A&NZIP condensed matter and materials meeting, Feb 2003, Wagga Wagga NSW, [online paper].
- F.C. Loughnan and F.I. Roberts, Australian Journal of Earth Sciences, vol. 37, p. 201 (1990).
R. A. Hobson, Journal of the Royal Society of Western Australia,
vol. XVI, pp. 57-70 (1930).
David W. Trainer, Jr., "Zebra Rock", American Minerologist, Vol.
16, p. 221-225 (1931). [online
- Peter J. Ortoleva, "Geochemical self-organization", ( New York, Oxford University Press, 1994).
H. Bracewell, Gems around Australia. Part 5 [Zebra stone]. Australian
Gemmologist, Vol. 17, p. 454-456 (1991). [page image in pdf]
H.-J. Krug, H. Brandtstädter, K. H. Jacob, "Morphological instabilities
in pattern formation by precipitation and crystallization processes", Geologische
Rundschau, Vol. 85, p. 19-28 (1996).
- Article from the Earth Museum at the University of Western Australia [pdf]. Good photo.
- Shards of zebra rock: an image from Ben and Andrea's travel blog.
article about Zebra Rock by Jan and Max Hedger.
The Zebra Rock Gallery, P.O. Box 97, Kununurra, Western Australia, 6743.
The Experimental Nonlinear Physics Group, Dept. of Physics, University
60 St. George St. Toronto, Ontario, Canada, M5S 1A7. Phone
(416) 978 - 6810