Skip to Content

Geology - Diamonds & Zebra Stone

Many of the landforms around and under Lake Argyle were originally formed over a billion years ago. Then approximately 350 million years ago, a massive upheaval occurred creating the spectacular landscapes now seen around the lake. This upheaval resulted in the “Halls Creek Fault” which runs the length of Lake Argyle in a south west to north east direction.

On the eastern side of the lake amongst the black soil plains can be found interesting limestone formations, agates, semi precious crystals, geodes etc. As you travel west the open black soil plains begin to rise into a serious of small hills mostly composed of sedimentary shales interspersed with quartz outcrops. On the western side of the lake is the massive Carr Boyd range. Rising up to 300 metres above the lake, these ranges consist mainly of quartzite, sandstone and shale.

The area is rich in minerals with deposits of uranium, gold, copper and the richest deposit of diamonds in the world!


Diamonds were first discovered in 1979 when geologists tracked the source of diamonds up the Ord River to Smoke Creek at the south western end of Lake Argyle. When they did finally arrive at the source of the diamonds they realized that they had discovered an enormous deposit. Now known as the “Argyle Diamond Mine” it continues to be the largest producer of diamonds in the world by volume.

Pink Diamonds

A large proportion of the stones that are extracted are of industrial quality, but the gems that are produced are renowned for their quality and colours, especially the pink diamonds which can sell for over $1 million per carat.

Zebra Stone

The only known deposits of Zebra Stone 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 claystone or shale in the Ranford Formation. The age of Zebra Stone has been placed at 600 million years.

Zebra Stone is very attractive fine grained Siliceous Argillite ( indurated silt-stone or clay stone ) with rhythmic pattern of red bands or spots contrasting sharply with a white background. Most sites found to date are under Lake Argyle.

Since the discovery of Zebra Stone in 1924 it has to this day remained a geological mystery that continues to baffle scientists as to how the unique patterns formed in the stone.

Zebra Stone pieces and jewelry are available at the Lake Argyle Store/Information Centre.