Four copper objects that outlived the centuries

Why copper is the thing that stays

Wood rots, iron rusts away, textile falls apart. Copper does something else: it forms a thin oxide layer on the outside that seals off the metal underneath, and then it stops. That is why many of the oldest human-made objects we can still pick up are made of copper. Here are four of them, and all four are still around.

In short

• The temple of pharaoh Sahure at Abusir holds 405 metres of copper drainage pipe from around 2500 BC.
• Ötzi, the five-thousand-year-old ice mummy, carried an axe of copper whose ore came from southern Tuscany.
• Of all the Dead Sea Scrolls, one is made of copper; it survived two thousand years while the parchment beside it decayed.
• From 1761 the British navy coppered its hulls, and within twenty years half a fleet was sailing with copper below the waterline.
• The same property that preserved those objects is in a bottle or mug you buy today.

1. The oldest plumbing in the world, 2500 BC

At Abusir, south of Cairo, stands the mortuary temple of pharaoh Sahure. The excavation there uncovered a drainage system of 405 metres of copper pipe. The builders took sheet a good millimetre and a half thick, bent it around a wooden core and soldered the seam shut, producing a round pipe that carried water out of the temple.

That is not merely old, that is the oldest known water pipe we have. Four and a half thousand years later it is still lying there. And the material is exactly what a modern plumber makes pipework from, for exactly the same reason: copper bends without breaking and lasts longer than the building around it.

2. The ice mummy's axe, 3300 BC

In 1991 two hikers in the Ötztal Alps found a body in the ice. It turned out to be a man of about forty-five, dead for some 5,300 years, and he was carrying kit: a bow, arrows, a knife, and an axe with a copper blade.

That axe later produced the finest discovery of all. In 2017 researchers determined the lead isotopes in the metal and published the result in PLOS ONE. The ore had not come from the Alps around the corner, but from southern Tuscany, hundreds of kilometres to the south. So Ötzi walked around with copper that had come over the Alps through a trade network, in a period we long assumed people lived mostly locally.

3. The scroll that was made of copper, first century

The Dead Sea Scrolls are famous for their parchment, but there is one exception among them. The scroll numbered 3Q15, found in cave 3 near Qumran, is neither parchment nor papyrus. It is copper with about one percent tin, and the text was hammered into it letter by letter.

The contents are just as remarkable: a list of sixty-four places where gold and silver were said to be hidden, with distances and directions. Whether that treasure ever existed, nobody knows. What we do know: of everything that lay in those caves, this is the piece that came through the fight with time best. Parchment turns brittle and falls apart; the copper held its shape for twenty centuries.

4. The fleet with copper below the waterline, 1761

For a wooden sailing ship the shipworm was the great enemy: a mollusc that ate its way through the hull. On top of that came fouling by barnacles and weed, which made a ship slower and slower.

In 1761 the British navy tried something new on the frigate HMS Alarm: the entire hull below the waterline was sheathed in copper plate. It worked. In seawater copper forms a thin film of copper oxychloride that slowly releases, and fouling has no appetite for it. The Alarm stayed clean and fast.

Twenty years later it was policy. By 1781, 82 ships of the line, 115 frigates and 182 smaller vessels were sailing with a copper skin. English kept an expression from it: something guaranteed sound has been called copper-bottomed ever since.

What that means for the copper in your kitchen cupboard

Four objects, a good four thousand years apart, and the same property underneath every time: copper seals itself and then carries on. You see the same thing on the Statue of Liberty, standing in sea air since 1886 with a green layer under a tenth of a millimetre on it. How that works is in why copper turns green or black.

It is also why copper fits a circular loop so well: the metal loses none of its properties when melted down, and most of everything ever mined is still in use somewhere. Those figures are in why more and more people are choosing copper again.

A copper jug or water bottle you buy today is made of the same stuff as Sahure's pipe. With normal use it will last a lifetime, and then once more. Browse the whole collection.