Zebra Stone

The unique Zebra Stone has been placed at 600 million years in the Upper Proterozoic era or Pre-Cambrian period. The only known deposits in the world have been discovered in the East Kimberley, Western Australia.

The stone consists of a fine grained siliceous argillite (indurated siltstone or clay stone) with rhythmic patterns of red bands or spots contrasting sharply with a lighter background. It is not known how the regular patterns were formed, but the red stripes are colored by ferric (iron) oxide. Geologists have investigated Zebra Stone without producing any valid explanation of its origin. The stone’s unsurpassed natural beauty typifies the color and spirit of Australia and some have said the stone has a special quality bringing luck.

This unique rock type occurs in the Ord River district of Western Australia in the area of Lake Argyle. Unfortunately, due to the construction and filling of the Ord River dam, the main outcrops of the rock formation are now hidden from view.

The name zebra stone was originally coined to describe the stripe-like colour banding. At first glance zebra stone appears to be made up of regular layering of red-brown and greyish-white layers. Closer examination shows that such distinctive bands are not always continuous but often grade into most unusual rhythmic patterns such as a series of spot-like markings. The rock is fairly soft, with a hardness of only 3 on Moh’s scale.

Occurring in seemingly randomly scattered lenses, zebra stone is believed to be 500-600 million years old. The texture and mineralogy of this rock leave no doubt that it was deposited as a sediment under calm or deep water. The remarkable patterns observed in zebra stone appear to contradict the principles of layering and stratification which are characteristic features of all sedimentary rocks. From this viewpoint it would seem that forces other than gravity operated on this rock to create the patterns.