elements
Copper
Cu
- Also known as
- cuprumnative copper
- Crystal system
- cubic
- Hardness
- 2.5–3 on the Mohs scale
- Lustre
- metallic
- Colour
- Metallic red-orange, weathering to green
- Where it forms
- In the oxidised zones of copper deposits and in basalt cavities. The Keweenaw Peninsula in Michigan produced native copper in masses weighing hundreds of tonnes.
- Chiefly from
- Michigan, United StatesKatanga, Democratic Republic of the CongoChileAustralia
Why it is that colour
Like gold, copper absorbs part of the blue end of the spectrum, giving the warm colour. The green patina is a mixture of copper carbonates and sulfates — essentially malachite growing on a roof.
Safety
Metallic copper is safe to handle and is used for cookware and plumbing. Copper salts are toxic, and copper bracelets sold for arthritis have been tested in controlled trials and found no better than placebo. Excess dietary copper causes liver damage, and Wilson’s disease is a genetic disorder of copper accumulation.
Where it comes from
Chile and Peru dominate world production. Congolese copper and cobalt come from the same belt, with the artisanal mining and child labour concerns documented there. Copper demand is rising sharply with electrification.
Historical use
The first metal worked by people, from around 9000 BC, because it occurs native and is soft enough to hammer cold. Alloyed with tin it becomes bronze, which named an age. The Statue of Liberty is copper, and its green is the patina described above.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Venus in the alchemical scheme, and associated with love and beauty — a link that runs through the metal’s ancient association with Cyprus, from which its name derives. Copper mirrors and cosmetic use reinforce the connection. The modern copper bracelet is a twentieth-century folk remedy rather than an ancient one.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Copper begins metallurgy, and it begins it because of an accident of chemistry: it is one of very few metals that occurs as metal. A person who picks up a lump of native copper has picked up something that can be hammered into a shape without any understanding of smelting at all.
The copper bracelet is worth a note because it is one of the few metaphysical-adjacent claims that has actually been tested properly. A randomised trial published in 2013 compared copper bracelets and magnetic wrist straps against placebo devices in rheumatoid arthritis, and found no difference on any outcome. An earlier trial in osteoarthritis found the same. The devices are harmless and they do not work.
Identity checked against IMA-CNMNC master list, June 2025.