Copper vs Zinc

Copper was the first metal people learned to hammer, shape and eventually melt, many thousands of years ago. It gave its name to the Copper Age and, mixed with tin, to the Bronze Age. Today it matters more than ever, because copper carries electricity better than any metal except silver, and the modern world runs on wires.

• The Statue of Liberty is clad in copper sheet, and its green colour is a protective layer of copper carbonates and sulfates that formed within a few decades of its unveiling.
• Octopus and crab blood is blue because it carries oxygen with a copper protein, haemocyanin, rather than iron-based haemoglobin.

Zinc has a habit of doing its work unseen. It coats steel lampposts, crash barriers and roofing so they do not rust. It sits alongside copper in brass door handles, in the cases of alkaline batteries and in the cores of modern pennies. Inside your body, around three hundred enzymes need zinc to function, including ones involved in growth, immunity, wound healing and the senses of taste and smell.

• Zinc boils at a lower temperature than is needed to smelt its ore, so early European furnaces turned it straight into vapour that burned away in the flue.
• The Zawar mines in Rajasthan were producing zinc metal in sealed retorts centuries before Europe worked out how.