Chalcocite

A dark gray copper sulfide and one of the richest copper ores.

Chalcocite specimen — Photo: Didier Descouens, CC BY-SA 3.0, via Wikimedia Commons

How to identify chalcocite

Dark lead-gray, dulling to black.
Soft and sectile — a knife shaves it.
Heavy.

Often confused with

Galena
Galena is brighter, heavier and breaks into cubes.
Compare side by side
Acanthite
Acanthite is heavier and also sectile; a lab test may be needed.
Compare side by side

Where it's found

Bristol, Connecticut
Cornwall, England
Butte, Montana
Arizona

Uses

Copper ore.

Rock tumbling

Not suitable for tumbling.

Did you know?

It's nearly 80% copper by weight.

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