Bornite

A copper iron sulfide that tarnishes to brilliant purple and blue — the true 'peacock ore'.

Bornite specimen — Photo: Robert M. Lavinsky, CC BY-SA 3.0, via Wikimedia Commons

How to identify bornite

Bronze on a fresh break, quickly tarnishing purple and blue.
Soft — a knife scratches it.
Usually massive, rarely crystals.

Often confused with

Chalcopyrite
Chalcopyrite is brass-yellow inside.
Compare side by side
Covellite
Covellite is indigo-blue throughout.
Compare side by side

Where it's found

Butte, Montana
Chile
Mexico
Katanga, DR Congo

Uses

Copper ore.

Rock tumbling

Not suitable for tumbling.

Did you know?

It's named after Austrian mineralogist Ignaz von Born.

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