Gravity has been an essential force in mineral and coal processing for centuries. While some newer separation technologies developed during the industrial age are widely used, gravity-based separators remain the prominent means of producing concentrates from coal, iron ore, rare earths, industrial minerals, tin, and tungsten ores. Recent advances in gravity-based separation technologies have reduced previous particle size limitations and improved their effectiveness in treating mixed-phase particles as compared to competing technologies. It is now possible to achieve efficient, high-capacity gravity separations for ultrafine particles using gravity-based units that provide centrifugal forces many times that of natural gravity. Sophisticated research equipment provides opportunities for in-situ studies of processes, resulting in new fundamental theories and control schemes.