Oxidised zone copper minerals

This stunning polished slice of blue chrysocolla (copper silicate with water), green malachite (copper hydroxy-carbonate) and brown ironoxide- stained jasper (silicon dioxide) is from the DeGrussa Copper-Gold Mine in the Pilbara Block of Western Australia.

This amazing pattern of swirling colours has been likened to an aerial view of a tropical rainforest canopy. These large slabs from the oxidised zone of the orebody are now becoming very scarce and will soon be unobtainable.

The original deposit of primary copper sulphides formed in volcanic rocks on the seafloor about two billion years ago and was then overlain by sediments. Over millions of years the orebody was exposed at the Earth’s surface, where water, oxygen and carbon dioxide transformed the primary sulphides into colourful secondary copper minerals.