Thematic Articles

Natural rocks harbor diverse assemblages of magnetic mineral grains that record information about past dynamo activity and plate motions, among other processes. For much of its history, however, the field of paleomagnetism has counted on a thorough theoretical understanding of only very fine (≤100 nm) grains magnetized during heating. Here we review experimental and computational advances to move beyond this limitation. Magnetic field microscopy allows us to physically identify mineral grains carrying specific paleomagnetic signals, while nanotomography coupled with micromagnetic simulations offers, for the first time, a quantitative picture of how most naturally occurring magnetic grains behave across geologic time. Together, these techniques open the door to retrieving records from less-than-ideal rocks with complex geological histories.

Among the different methods used to probe the interior of planets and moons in the Solar System, the ones providing access to the electrical properties of rocks are particularly powerful. From field induction measurements to laboratory impedance spectroscopy experiments, several techniques explore the electrical response of geomaterials at different scales of observation, from planetary to atomic. Detailed snapshots of the Earth’s crust and mantle are obtained from the combination of magnetotelluric surveys with laboratory measurements. In space, induction observations complemented by electrical laboratory experiments have been key to defining the layered structure and thermal state of several terrestrial bodies. Future electrical investigations will continue to reveal the present structure of planetary deep interiors, which is necessary to decipher their evolution.

Far from being passive building blocks, minerals govern how Earth evolves and deforms, from seismic wave propagation to rock deformation and plate motion. This article explores how pressure builds within Earth and how minerals’ elastic response to compression and seismic waves reveals its internal structure. At higher stresses, beyond their elastic limit, deformation in minerals becomes permanent through crystal plasticity created by crystal defects and strongly enhanced by temperature. Over geological time scales, aggregates of crystals behave effectively as highly viscous fluids, enabling mantle convection and plate dynamics. Understanding Earth’s large-scale behavior therefore requires linking rock rheology to the mechanics of minerals down to crystal defects. By integrating observations, experiments, and models, we uncover the hidden rules connecting atomic interactions to planetary dynamics.

Heat is a fundamental driver of planetary evolution, shaping its interior, surface, and atmosphere. On Earth, the flow of heat powers dynamic systems that are essential to life. Thermochemical variations across the core–mantle boundary play an important role in regulating heat flow, which influences the dynamics of both the mantle and the core, including generation of the geodynamo. In this article, we focus on thermal transport and melting, including highlights of new technological developments in laboratory optics and synchrotron facilities. Here, we offer a perspective that highlights the spatial and temporal characteristics of these processes, where new developments expand our understanding of Earth’s thermochemical evolution, and hold promise for applications to other planetary bodies.

The study of minerals under light, spanning the ultraviolet, visible, infrared (UV-Vis-IR) spectrum, has played an important role in advancing our understanding of terrestrial and extraterrestrial materials. Here, we review light-based spectroscopic techniques across spatial scales in mineralogy and planetary science. Polarized light microscopy helps characterize optical properties, while vibrational and UV-Vis spectroscopies provide insights into mineral structures and compositions. In mineral physics, spectroscopy probes bonding environments, electronic structure, phase transitions, and elastic properties at high pressures and temperatures. In planetary science, UV-Vis-IR techniques from spacecraft and telescopes reveal planetary mineralogy. These methods support the search for habitable environments, planetary evolution studies, and resource identification. Furthermore, technological advances in portability, imaging, and data analysis have improved the precision and scope of mineralogical research.

Mineral science emerged from humanity’s earliest curiosity about the colors, hardness, and magnetic properties of stones and metals. Across centuries, observations by philosophers, naturalists, and early microscopists gradually revealed that these macroscopic traits arise from the hidden architecture of matter. The scientific revolutions of the 17th–20th centuries—from crystallography and optics to quantum mechanics and high-pressure experimentation—established the atomic foundations of minerals and transformed mineralogy into a modern physical science. Today, mineral physics links nuclei, electrons, defects, and crystal structures to the behavior of Earth and planetary interiors. This sets the stage for this Elements issue, showing how insights across disciplines continue to shape our understanding of minerals from atoms to planets.