Chalcopyrite

Copper iron sulphide (CuFeS₂), commonly called copper pyrites — the commonest and most widely worked ore of copper in Britain and worldwide.

Historical usage

Chalcopyrite has been the world's leading source of copper for at least five thousand years, and was the principal copper ore raised across Cornwall and Devon, where large, well-formed crystals were noted at localities including Carn Brea. It typically occurs alongside cassiterite in the south-west's tin-copper lodes, as well as with iron pyrites, chalybite and blende elsewhere in the same veins.

How it worked

Brass-yellow with a metallic lustre and greenish-black streak, chalcopyrite is distinguished from the similarly coloured iron pyrites chiefly by being noticeably softer — it can be scratched with a knife or nail, where iron pyrites resists — and by its deeper colour; treated with nitric acid it releases sulphur and forms a green solution that turns deep blue with added ammonia, a simple field test miners and assayers used to confirm it.

Why it was used

As the commonest copper ore mineral by far, chalcopyrite was the everyday target of Cornish and Welsh copper mining, though it yields comparatively modest copper content compared with rarer, richer ore minerals — meaning large tonnages had to be raised and dressed to make a profitable return.

Risks & limitations

Ore grade varied considerably by locality and depth, and because chalcopyrite is so much less copper-rich than some rarer secondary copper minerals, mines relying on it needed high throughput and efficient dressing to stay profitable as easily worked, near-surface ore ran out.

Regional variation

The dominant copper ore across Cornwall and Devon's tin-copper lodes, and worked wherever copper mining took place in Britain, from Anglesey's Parys Mountain to the orefields of mid-Wales.

Images

Mines associated with this term

Included only where MineArchive's own research gives a reasonable evidential basis — not every mine where this might plausibly apply.

• Talnotry Mine — Dumfries and Galloway (well documented example)
  Named in this record’s history: “…include nickeline, gersdorffite, pyrrhotine, pentlandite and chalcopyrite — has since made it a Geological Conservation Review site and Site…”

Sources

1. (secondary) 1911 Encyclopædia Britannica/Copper-pyrites — Wikisource
2. (secondary) Chalcopyrite: Mineral Uses and Properties — Geology.com

Record created: 27 August 2026 · Last researched: 27 August 2026