After a start in theoretical solid-state physics, Ekhard Salje has become one of the world leaders in applying the theoretical and experimental advances of physics to problems in mineralogy and solid-state-physics. His work on feldspars has shown how the internal state of order and strain in a mineral can be understood and related to its geological history via a few parameters in the Landau free energy. This approach has been successfully extended to kinetics and resulting textures. He was first to use the line shape of ‘hard’ phonons to measure degree of order, a technique particularly useful in complex mineral structures. He studied metal–insulator transition in terms of the behaviour of polaron gas. The stability of minerals and functional materials was elucidated by resonance methods and the avalanche properties of collapsing porous materials was shown to reproduce the acoustic fingerprints of earthquakes and the stability of mine shafts. He demonstrated atomic mechanisms of acoustic emission during mechanical and electric perturbations. His work on multiferroic materials in physics and material sciences is internationally leading.