Chalcopyrite

Copper iron sulfide and the world's most important copper ore. Brassy yellow, often tarnished to rainbow purples and blues.

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

How to identify chalcopyrite

Deeper, greener yellow than pyrite.
Iridescent tarnish on older surfaces.
A knife scratches it (pyrite resists).
Greenish-black streak.

Often confused with

Pyrite
Pyrite is paler, harder and forms cubes.
Compare side by side
Gold
Gold is malleable and leaves a gold streak.
Compare side by side

Where it's found

Chile
Peru
Cornwall, England
Missouri

Uses

Copper production.

Rock tumbling

Not suitable for tumbling.

Did you know?

Much 'peacock ore' sold in shops is chalcopyrite treated with acid to make it iridescent.

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