Pegmatite is one of the important type of rocks. If we have to define Pegmatite in general, Pegmatite rock is a holocrystalline, intrusive igneous rock which is composed of interlocking phaneritic crystals. Pegmatite comes under Igneous Rocks. All Igneous Rocks have similar properties and formation process. Along with Pegmatite Definition, know more about the History of Pegmatite, Etymology of Pegmatite in next sections.