Process that occurs during crystallization of certain igneous rocks , in which liquid is separated from the crystals by pressure.
As the crystals grow and accumulate in magma , a crystal mesh may be formed. Pressure applied by the weight of crystals above or by outside forces may force the more mobile liquid out of the mesh and also may fracture or crush the remaining crystals. Filter-pressing has been used to explain the formation of rocks consisting of only one kind of mineral.