segregation

In geology, "segregations" refer to specific types of inclusions within igneous rocks that are closely linked to their host rock and are often enriched in certain minerals found in the host rock. These segregations can vary in size from small pods to extensive layers. They can form from early-stage crystal accumulations that settle by gravity within magma, or from late-stage concentrations of coarse-grained material that develop in place.1

A particular type of magmatic segregation involves liquid immiscibility, where a cooling magma separates into droplets of a second magma with a different composition. These immiscible liquids, like oil and water, do not mix. This process can lead to the concentration of elements and the formation of rich ore deposits, such as those containing copper, nickel, and platinum-group metals.2