01Decisive
Cut it with a steel knife
Chalcopyrite at 3.5–4 takes a knife easily. Pyrite at 6–6.5 does not, and will instead scratch the blade. This is the whole separation between the two brassy sulphides.
Pyrite · Lovenhall Stone
How to Identify Chalcopyrite
The other brassy sulphide. Softer than pyrite, often iridescent, and mistaken for gold just as often.
Spain, Peru, Italy, and almost every sulphide deposit on earth
Chalcopyrite is copper iron sulphide, and it is the world's main copper ore. It shares pyrite's brassy metallic look but runs a deeper, more golden, often slightly greenish yellow, and it frequently tarnishes to a blue-purple-green iridescence sold as peacock ore.
It separates from pyrite on hardness. Chalcopyrite is 3.5–4, soft enough that a steel knife cuts it easily and a copper coin will just mark it; pyrite at 6–6.5 is untouched by both. Both give a greenish-black streak, so streak alone tells you neither is gold but does not tell them apart.
Worth knowing because chalcopyrite is the brassy mineral most often present when someone genuinely is looking at a metal deposit — it just happens to be a copper deposit rather than a gold one.
Model-specific checks
What decides a Chalcopyrite
These apply to this model and not to the rest of Pyrite. Work them alongside the maker's general checks, not instead of them.
02Strong
Look for the iridescent tarnish
Chalcopyrite readily develops a blue, purple and green surface film. Pyrite dulls and rusts instead. Bright iridescence on a brassy sulphide points to chalcopyrite — or to bornite, softer still.
The market
What a Chalcopyrite does on the secondary market
Inexpensive. Iridescent 'peacock ore' specimens sell for a few dollars to low tens.
An orientation for honest, unrestored condition — never an appraisal, and never a quotation.
All the Pyrite checks
Free tools of the room
Lovenhall StoneRead the stone itself
The tests tell you what it is. The instrument reads a photograph and offers a name to start from — then hands you back to the tile and the coin, which are what settle it.
Free on iPhone & iPad. An estimate, never an appraisal.
Or write to the house