Porphyroblast

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Porphyroblast [Mechanics]:A grain larger than the surrounding matrix. Mineral grains that have recrystallized during or after the development of a structure (foliation, lineation). The porphyroblasts may have re-equilibrated to new conditions at that stage. If the mineral has grown during deformation can be dated with respect to a single phase deformation. However, the mineral grains could have only rotated to form a fabric, without recrystallization and re-equilibration.