Plutonic Rocks: rocks formed by the solidification of magma that has intruded within the Earth’s crust. Since the magma is enclosed within the crust by other rocks that provide thermal insulation, the cooling process occurs over a very long period, allowing the entire molten mass to crystallize. The resulting intrusive igneous rock is fully composed of large crystals visible to the naked eye (holocrystalline texture). However, some minerals (such as Quartz) may not develop their characteristic crystal shape due to the limited residual space among already crystallized minerals. Based on their morphology, size, and relationships with surrounding rocks, plutonic rocks can be classified as: batholiths, stocks, lopoliths, laccoliths, pegmatoids, sills, and dikes.
