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The only known deposits of Zebra Rock in the world have been found near Kununurra in the East Kimberley of Western Australia.
The deposits are found in small reef outcrops of Stratified Clay-stone or Shale in the Ranford Formation.
The age of Zebra Rock has been placed at 600 million years old, in the Upper Proterozoic Era or Pre-Cambrian period.
Zebra Rock is very attractive, fine rhythmic pattern of brown bands or spots contrasting sharply with the white background.
Zebra rock is a siltstone, laid down at the base of the river bed (in this case the river Ord) as sedimentary rock, 600 million years ago. Recall that silt is finer than sand but not as fine as clay. So zebra rock is of intermediate density but still porous. It will readily take up water.
The best sites found to date are adjacent to and/or in Lake Argyle. Zebra Rock is the most widely known of the decorative siltstones in the Ranford Formation, an ancient geological structure that stretches for 100s of km following the alignment of the Halls Creek Fault.
|Ranford Formation.pdf (PDF — 33 KB)|