Zebra stone or zebra rock is a very unique reddish-brown and white-banded sedimentary rock from the east Kimberley of Western Australia. Composed essentially of small particles of quartz and ‘sericite’ (fine-grained white mica), zebra rock also contains the minerals kaolinite, dickite and alunite. It was formed during the late Precambrian, around 670 million years ago. Several explanations for it's formation have been proposed. One explanation being the patterns were formed by formed by the rhythmic precipitation of iron oxide rich bands during the alteration of the rock by percolating fluids. Another explanation is that the patters are caused by cyanobacterial mats infilling ripple marks in low energy shallow marine environments which would make it a Microbialite trace fossil.