A new iron compound hints ‘primordial’ helium hides in Earth’s core

Helium atoms filled gaps in iron crystals under high pressure and temperature

illustration showing the location of helium in the helium-iron compound

Under high temperature and pressure, helium atoms (red circles) move into the spaces between iron atoms (red circles with black centers) in a piece of iron metal, as show in this map called an electron localization function.

Han Hsu/ National Central University

Scientists have coaxed one of the universe’s most stubborn elements into a new compound.