Nickel

Nickel was isolated in 1751 by the Swedish mineralogist Axel Fredrik Cronstedt, who extracted it from an ore that resembled copper ore but contained no copper. It is a hard, silvery, corrosion-resistant magnetic metal, central to stainless steel, coinage, plating and rechargeable batteries, and a major constituent, with iron, of the Earth's core. Resistant to corrosion and strong at high temperature, nickel is essential to stainless steel and to the superalloys of jet engines and gas turbines, it plates and hardens other metals, and it is a major component of rechargeable batteries. Long before Cronstedt named the element, nickel-iron meteorites were prized across many ancient cultures as sky-iron, a rare workable metal that fell from the heavens; Tutankhamun's dagger blade, analysed in 2016, proved to be meteoritic, its nickel content matching known meteorite compositions and confirming ancient Egyptian accounts of iron from the sky.

The American five-cent coin took the popular name nickel after the metal was adopted for its composition in 1866, and Canada, the world's leading nickel producer through much of the twentieth century thanks to the vast Sudbury deposit, itself the remnant of an ancient meteorite impact, minted actual nickel coins for decades.

Like cobalt, nickel bears a name drawn from mining superstition. The ore Cronstedt studied was called Kupfernickel by German miners, meaning copper-nickel or, more pointedly, Old Nick's copper, Nick being a name for the Devil. The miners cursed the mineral because it had the reddish look of copper ore yet stubbornly refused to yield any copper, and they held a malicious spirit responsible. When Cronstedt proved that a genuine new metal, not the Devil, was the hidden ingredient, he kept the second half of the miners' epithet as its name. Nickel and cobalt together are the periodic table's memorial to the goblins and devils that pre-modern miners believed lurked in the deceptive ores of the deep workings.

Nickel has a mundane but widespread modern legacy: it is the most common cause of metal contact allergy in humans, provoking itchy rashes from cheap jewellery, watch backs, belt buckles and coins in a significant share of the population, especially women, who statistically show higher rates of nickel-related skin sensitisation. The European Union's Nickel Directive, in force since 1994, restricts the amount of nickel that can leach from items in prolonged skin contact, a regulatory response to a problem that traces back to the same reactive, faintly ore-mimicking metal the old miners once blamed on a devil in the rock.