Peacock copper crystals.
“Peacock Ore”, which is sold to amateur mineral collectors and tourists, is often labeled as a variety of Bornite. However, most Peacock Ore in reality is Chalcopyrite treated with acid, which produces a strongly colored iridescent tarnish.
The colours on these pretty rocks grows naturally in a very thin layer on the top of the rock. Peacock Ore is also known as Bornite – it’s a copper iron sulfide mineral commonly found in hydrothermal veins and contact metamorphic rocks which tarnishes to iridescent shades of blue, purple, green and gold.
The ore is very soft, with a hardness of three on the Moh’s hardness scale. This opaque rock has a beautiful metallic luster that is a result of the metallic elements within the ore.Peacock ore is very brittle and streaks a gray black color.
What is the difference between chalcopyrite and bornite?
Bornite commonly occurs with other copper sulphide minerals such as chalcocite and weathers, or “oxidizes”, to malachite. Chalcopyrite is the most common ore mineral for copper. Chalco comes from the Greek word chalko, meaning copper. Chalcopyrite is commonly found in sulphide deposits in most ore-forming environments.
Peacock Ore (Bornite) is a crystaline variety of Chalcopyrite and they have very similar properties. Bornite is the name of the natural, untreated stone, while Peacock Ore usually describes its heat-enhanced state. Bornite has naturally occuring rainbow colours, but they are rare in nature.
What does bornite look like?
Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places. Its striking iridescence gives it the nickname peacock copper or peacock ore.