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Amethyst

Chalcopyrite

Goethite

Mineral Identification

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Bornite (Cu₂FeS₄)

The Peacock copper.

Bornite is another copper ore like Chalcopyrite,  it is often known as 'peacock copper' because its surface is often coated with a dark greeny, blue, purple iridescent tarnish.  It occurs as a primary deposit of many copper lodes. In Cornish mines it was known as 'horse-flesh' ore, because it has is pink copper colour. 

Data Panel: Iron Sulphide: Copper ore: Bornite Cu2FeS4  Copper iron sulphide
colour	Reddish bronze, tarnishes to blue, green and purple
hardness	3
Crystal system	Isometric
Crystal habit	Crystals rare but rough
Lustre	Metallic
Streak	Grey-black
Fracture	Conchoidal
Other characteristics	Tarnishes in hours.

 

 Photograph reproduced with the kind permission of the Geevor Archive