Fluid Inclusions

Fluid inclusions are small droplets of fluid that have been trapped within crystals, either during primary growth from solution or at some later stage, usually as a result of recrystallization along healed micro-fractures. They are ubiquitous in both naturally occurring minerals and in laboratory-grown crystals. Fluid inclusions provide a unique fossil record of the various fluids responsible for the formation and evolution of rocks and minerals throughout the history of the Earth. Despite their small size (usually less than 20 μm), their chemical composition and physical properties can be readily determined, and the data may be used to estimate the temperatures, pressures, and physicochemical nature of the fluid at the time of trapping. This information has made an immense contribution to the development of modern theories of ore genesis, igneous petrogenesis, diagenesis, and petroleum migration and accumulation, and to our understanding of the importance of the fluid phase in a wide range of geological processes.