Mineral · Native elements
Native copper
Cu
Native copper occurs as branching dendrites, sheets and rare cubic crystals in the Keweenaw Peninsula of Michigan, Ray (Arizona), Bisbee and Chile; Michigan 'float copper' and copper-with-silver 'halfbreeds' are American classics. It tarnishes brown and green and is often acid-cleaned to a bright salmon colour. Malleability and colour identify it.
| Formula | Cu |
|---|---|
| IMA status | grandfathered |
| Crystal system | Cubic |
| Mohs hardness | 2.5–3 |
| Group | Native elements |
| Type locality | None (known since antiquity) |
| Streak | Copper red |
| Specific gravity | 8.9 |
| Reference list | IMA List of Minerals (RRUFF) — verify formula and status against the current list |
Fakes and treatments
Some 'crystallised copper' specimens are electroformed or cast; genuine crystals have natural edge rounding and are often partly covered by cuprite.
Elsewhere
Cite this article
Stratum Strata. "Native copper" (Mineral). Stratum Strata pack 2026.09, as of 2026-09-21. https://stratum.black/strata/minerals/native-copper. Accessed 2026-09-21.
@misc{stratum-native-copper,
title = {Native copper},
author = {{Stratum Strata}},
howpublished = {\url{https://stratum.black/strata/minerals/native-copper}},
year = {2026},
note = {Mineral article, Stratum Strata pack 2026.09, as of 2026-09-21; sources: stratum, wikidata, commons. Accessed 2026-09-21.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.