Could a superheavy element – heavier than anything previously found in nature or made in the lab – exist naturally in the rocks of Earth? A team of physicists says they have detected a few exceptionally massive atoms – which they say could be element 122 – in a solution prepared from natural minerals. But other scientists are highly sceptical of the claim.

The heaviest element known to occur in nature is uranium, which contains only 92 protons, putting it 30 places below the putative new element in the periodic table. In the laboratory, physicists have managed to create elements up to 118, but they are all highly unstable.

Amnon Marinov of the Hebrew University of Jerusalem led a team that analysed a purified solution of thorium (element 90) by running it through a mass spectrometer, which can measure the mass of individual atoms. The thorium should have an atomic mass close to 232 (including neutrons), but the team saw a handful of counts with a much greater mass – just over 292.