Zebra rock is one of those amazing creations of Mother Earth for which no one has an explanation. Yes its a sedimentary rock but to date no satisfactory explanation has been given for its unique patterning and layers. Various estimates of its age place it at at least 500 million years old with some estimates into the billions of years. This zebra rock comes from the Kununurra district in the East Kimberley region of Western Australia and is unique to this area, it is not found anywhere else in the world (that I am aware of). This land is ancient.
It is a distinctly reddish-brown and creamy-white sedimentary silted rock with various shades in between. It is primarily comprised of fine grains of quartz and 'sericite' (fine-grained white mica). The reddish-brown colouration is due to iron-oxide.
This material is renown for its 'zebra' like patterning (hence its name) and the variety is really quite astounding. There is the classic zebra rock that has the roundish 'blob' like markings (#z2), and a more layered material known as 'Okapi' (#z3). And of course there are combinations of the two (#z1).
The grain of zebra rock ranges from an extremely fine grain, almost porcelain, through to a fairly course grain. This is all probably to do with how the sediment as settled. Take a handful of dirt and drop it into a clear jar of water and the heavier course material sinks first and gradually the finer material settles on top. The hardness can vary as well and it seems that the finer the grain the harder it is, but not always.
Zebra rock, particularly the fine grain material, reminds me alot of 'pipestone' (catlinite) from Minnesota. It is very similar in nature and can be carved and worked in the same way. It can be worked with hand tools such as a hacksaw, files and sandpaper (though it might require some elbow grease). Like pipestone it also comes in a variety of hardnesses.
Zebra rock is perfect for carving!