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Zebra Rock

Zebra Rock (also known as 'zebra stone') is an ancient siltstone found in the East Kimberley region of far northwest of Western Australia in the Ranford Formation a region that is now occupied by Lake Argyle. It is so named because it appears as alternating dark and light bands comprising a continuous fine siltstone. Siltstone is a sedimentary rock that is finer than sand but not as fine as clay;. It is that intermediate density rock formed at the base of river beds by sedimentation over a period of time. The dark bands are iron and the pale bands silica. The elemental composition of the zebra rock is well known and results have been published in the scientific literature.

Zebra Rock is estimated to be 600 million years old. It has not been found elsewhere in Australia or any where else in the world. The mystery of how zebra rock was formed has occupied the minds of many researchers for over 50 years. It is commonly held that the colour banding of zebra rock was probably formed "'by the rhythmic precipitation of iron oxide (hematite) rich bands during the alteration of the rock by percolating fluids (fluids migrating through the rock". However, in spite of much research effort there is presently no consensus.

Several workshops operate in the Kununurra area to fashion the rock into ornamental gifts and jewellery

In this article we will learn about the distribution, composition and proposed origins of the rock. Contributions from others are welcome.