49 Fun Facts About Copper

What is the chemical symbol for copper?

Cu abbreviates the metal's Latin name, not its English one; Co, the letters an English speaker might expect, belongs to cobalt instead, and Cr to chromium.

Which two metals sit beneath copper in group 11 of the periodic table?

Silver and gold complete the column; chemists nickname the trio the coinage metals, because all three were being struck into money long before anyone drew a periodic table.

Copper is the usual hardening metal in which precious alloy, hallmarked 925?

Sterling silver is 92.5% silver, hence the 925 stamp; pure silver is too soft for cutlery and jewellery, so the remaining 7.5% is usually copper, added to make it harder and stronger.

Which island gave copper its name?

Cyprus supplied much of Rome's copper, so the Romans called the metal aes Cyprium, 'metal of Cyprus', and over the centuries the phrase wore down into the word copper.

Which pure metal is the only one with higher electrical conductivity than copper?

Silver is the only metal that conducts better, and only slightly; as a precious metal it costs far too much for the job, so copper became the standard that other conductors are rated against.

What colour is a freshly exposed surface of pure copper?

Pinkish-orange shows only on a freshly cut surface: copper is one of the few metals that isn't grey or silver, and air soon dulls it to the reddish-brown most people picture.

What is the green patina on old copper roofs and statues called?

Verdigris was also made on purpose: from antiquity to the Baroque, artists let vinegar work on copper and used the green crust that formed as a pigment.

Which metal is alloyed with copper to make bronze?

Tin makes copper markedly harder, so bronze tools and weapons outlasted pure copper ones, and the alloy ended up giving a whole prehistoric era its name.

What is an alloy of copper and zinc called?

Brass is the metal of trumpets, trombones and tubas, which is why an orchestra simply calls that whole section 'the brass'.

The silvery outer layers of US dimes and quarters are 75% copper and 25% which other metal?

Nickel is only a quarter of that cladding; the five-cent coin actually called a 'nickel' is the same alloy right through, so it too is three-quarters copper.

Which country is the world's largest copper producer?

Chile's Andes hold giant porphyry deposits: low-grade ore, often less than 1% copper, mined on a vast scale, mostly from enormous open pits. Deposits of this kind yield well over half of the world's copper.

Under which president were Chuquicamata and other giant foreign-owned copper mines nationalized in 1971?

Salvador Allende's amendment passed congress by a unanimous vote in July 1971, taking over mines owned by the American firms Anaconda and Kennecott; two years later he was overthrown in a coup.

In which US state is Bingham Canyon, the deepest open-pit mine on Earth?

Utah's Bingham Canyon pit is more than 4 km across and can be seen from space; in 2013 one wall gave way in a massive landslide, which slowed mining there but did not stop it.

Which mining group owns the Bingham Canyon copper mine?

Rio Tinto began in 1873, when British investors bought an ancient mine complex on Spain's Río Tinto from the Spanish government; it runs Bingham Canyon today through its Kennecott arm.

Which brassy-yellow sulfide is the most abundant copper ore mineral?

Chalcopyrite's brassy shine gets it mistaken for gold; a scratch settles it, since gold is soft and leaves a yellow streak while chalcopyrite is brittle and leaves a dark greenish one.

Which prehistoric European was found with a complete copper-bladed axe some 5,300 years after his death?

Ötzi the Iceman's axe held a surprise: its copper came not from the Alps, where he died and where ore was already being worked, but from southern Tuscany, hundreds of kilometres away.

Which engineer designed the iron skeleton inside the Statue of Liberty's thin copper skin?

Gustave Eiffel hung the copper, only about as thick as two pennies, from flexible iron bars that act like springs, so the skin can move with heat and wind instead of cracking.

Which Montana mining city's copper output earned it the nickname 'the Richest Hill on Earth'?

Butte and its neighbour Anaconda produced nearly a third of the world's copper in the early 1900s, just as the spread of electricity sent demand for the metal soaring.

What did the green patina that slowly covered the Statue of Liberty turn out to do?

It protected the skin: the green coat is not creeping decay but a thin, stable layer over copper that had started out a dull brown, so the statue was left to stay green.

Which Great Lakes state's Keweenaw Peninsula drew a rush of copper miners in the 1840s?

Michigan took the Upper Peninsula reluctantly, as a consolation for giving up its claim to the land around Toledo; the copper found there then brought the state great wealth.

Which vodka cocktail is traditionally served in a copper mug?

A Moscow Mule was dreamed up to shift slow-selling vodka and ginger beer; its Hollywood vogue raised the profile of vodka, which went on to become America's most popular spirit.

Which gemstone, prized from ancient Egypt to the American Southwest, is a copper phosphate mineral?

Turquoise forms only in a few dry, barren places, where acidic, copper-rich groundwater seeps down and reacts with phosphorus-bearing minerals in the rock.

Which planet did alchemists pair with copper?

Venus was the alchemists' own name for copper: they matched each of the seven metals they knew to one of seven heavenly bodies, so a single sign, ♀, stood for both the planet and the metal.

Which copper-based colour is regarded as the world's first synthetic pigment?

Egyptian blue, a calcium copper silicate, dropped out of use after Roman times and the way to make it was forgotten, until modern chemists analysed old samples and worked the recipe out again.

Which copper-based protein gives horseshoe crabs and most molluscs blue blood?

Hemocyanin is blue only while it carries oxygen and turns colourless without it; our own blood does the same job in red, using iron-based hemoglobin.

Which genetic disorder causes copper to accumulate in body tissues?

Wilson's disease often leaves a visible clue: copper deposited in the cornea forms a green-to-brown ring, the Kayser-Fleischer ring, around the coloured part of the eye.

What is the single biggest use of copper, taking about 60% of it?

Electrical wire and cable take the lion's share because copper carries current superbly, pulls into thin strands without breaking, and resists corrosion.

Which silversmith and American Revolution patriot opened North America's first successful copper rolling mill in 1801?

Paul Revere disliked the young republic having to import its sheet copper, so he built a mill of his own; its copper went on to cover the dome of the Massachusetts State House.

Which cheaper metal replaced copper in the wiring of many US homes from the mid-1960s, with fiery results?

Aluminium went in when copper prices jumped; the weak point proved to be the connections at outlets and switches, which worked loose, overheated and started fires.

The Great Copper Mountain, a mine now preserved as a World Heritage Site, is in which Swedish town?

Falun's mine also coloured the country: Falu red, the paint on wooden houses and barns across Sweden, takes its pigment from a by-product of the copper workings.

A list of buried treasure engraved on sheets of copper was found among which collection of ancient manuscripts?

Dead Sea Scrolls are nearly all parchment or papyrus; the copper one, found in 1952, is no literary work at all but a bare list of 64 places where valuables were buried or hidden.

Flash smelting of copper was pioneered in the 1940s by Outokumpu, a company from which Nordic country?

Finland's Outokumpu first ran the process at Harjavalta in 1949: dried, powdered ore is mixed with oxygen and ignited as it leaves a nozzle, a method that also cuts the sulfur pollution of older smelters.

Which African country, long reliant on copper exports, has a province simply named Copperbelt?

Zambia helped found CIPEC in 1967: a club of copper exporters often likened to OPEC, it never managed to match the oil cartel's grip on prices.

Which country is the world's biggest buyer of copper, importing more than any other?

China buys the most because its vast industry dominates world demand for the metal, and its solar, wind and electric-car makers now add to the appetite.

Since 1982, the US cent has been a thin copper plating over a core of which metal?

Zinc makes up 97.5% of the modern cent and copper just the 2.5% on its surface; until 1982 the proportions were close to the reverse, at 95% copper.

What were US cents briefly made of in 1943 because copper was needed for the war?

Zinc-coated steel stood in for a single year; a few 1943 cents were struck by mistake on leftover copper blanks, and those errors are now among the best-known rarities in American coins.

Bordeaux mixture, the classic vineyard fungicide, is lime mixed with which blue copper compound?

Sulfate of copper was first sprayed on roadside vines in the Médoc simply to put off grape pilferers; in 1882 a Bordeaux botanist noticed that those vines escaped mildew.

Which country's navy pioneered copper sheathing of ships' hulls in the 18th century?

Britain's navy coppered the whole bottom of the frigate HMS Alarm in 1761, after she came home from the West Indies in terrible condition; the plates kept shipworm and weed off the hull.

In which US state does the abandoned copper-mining town of Kennecott stand beside a glacier inside a national park?

Alaska's Kennecott processed nearly $200 million worth of copper between 1911 and 1938, then closed as the rich ore ran low; its empty mill town is now a National Historic Landmark.

Which US state produces more copper than all the other states combined?

Arizona already ranked first early in the twentieth century, and it shows: state law puts a copper-coloured star at the centre of the Arizona flag.

At which ancient North American city did archaeologists find a workshop for making Mississippian copper plates?

Cahokia's metalworkers, based beside Mound 34, hammered and annealed copper that had usually travelled hundreds of miles south from the Great Lakes region.

Which archaeological term names the Copper Age, when metal tools first joined stone ones?

Chalcolithic is built from the Greek words for copper and stone, because people of the period made their first metal tools while still relying on stone ones.

Shakudō, a Japanese copper alloy with a little gold in it, traditionally decorated the fittings of which weapon?

Swords carried guards and other fittings made of shakudō, which looks like plain bronze until a chemical bath turns its surface a deep black resembling lacquer.

A copper bowl is the chef's traditional tool for whipping what?

Egg whites beaten in copper make a foam that is harder to ruin; a 1984 study in the journal Nature traced the effect to copper binding with conalbumin, one of the proteins in the white.

Which of these foods is among the richest natural sources of copper in the diet?

Oysters and other shellfish head the list, with liver, nuts and whole grains; the body needs the copper to work with iron in forming red blood cells.

Alderley Edge, England's oldest known metal-mining site, was first dug for copper in which age?

The Bronze Age miners left their stone hammers behind, and an oak shovel found in the old workings in the 1870s was later carbon-dated to around 1750 BC.

Copper is the third most recycled metal by volume, after which two?

Iron and aluminium are recycled in greater tonnage, but copper loses none of its properties when remelted, and scrap already supplies about a third of the copper the United States uses.

Alloying gold with a generous share of copper produces which coloured gold?

Rose gold gets its blush from copper, and the more copper in the mix the redder it turns; white gold, by contrast, is paled with white metals such as palladium.

Which president's portrait has been on the copper-coloured US cent since 1909?

Abraham Lincoln arrived on the cent for the centenary of his birth; until then putting a president on a circulating coin had seemed too monarchical, an objection George Washington himself had raised.