GOLD readily forms alloys with the precious metals silver and palladium, but it normally blends with cheap iron about as well as oil mixes with water. That has now changed, with the creation of a gold-iron alloy that is held together by magnetism.

The arrangement of atoms in an alloy changes the chemical properties of its constituent metals and makes it potentially useful to catalyse reactions. This prompted Sylvie Rousset and colleagues at the Denis Diderot University, Paris, and the French National Centre for Scientific Research to explore creating one from gold and iron. But creating a gold-iron alloy …