Metamorphic rocks are product of transformation or solid-state recrystallization of existing (protolith) igneous, sedimentary, and metamorphic rocks, due to change in physical and chemical conditions, principally temperature, pressure and introduction of chemically active fluids and gases. Metamorphism alters the mineral composition including formation of new minerals (garnet, zoisite, kyanite, chlorite, biotite, sericite, staurolite, sillimanite, talc and andalusite). Sources of temperature are geothermic gradient, effect of magmatic body and friction in rock masses of tectonic movements following prograde or retrograde mechanism. Pressure is caused by weight of sediments or crust. Common textures are crystalline, granular, xenoblastic, idioblasts, granoblastic, and porphyroblastic. Structures include gneissic, schistose and slaty. Types of metamorphism are dynamic/kinetic, contact, regional and plutonic. Dynamic metamorphism due to mechanical deformations or dynamic stress during tectonic movements forms mylonites, flazer and augen gneisses. Contact metamorphism due to thermal effect of magma/lava generates skarn deposits. Regional metamorphism, caused by general increase/decrease in temperatures over large areas of continental crust, creates low-/high-grade metamorphic rocks like slate, phyllite, amphibolites, varieties of schists, para- and orthogneisses, quartzite, and marble. Plutonic metamorphism occurs at high temperatures and strong pressure in deeper parts of lithosphere producing granulites, eclogite and migmatites. Metamorphic rocks are exceptionally appreciated as decorative and building stone due to crystalline texture, layering, brilliant colors and excellent polishing capabilities.