Porphyry, formerly known as porphyry, is an igneous rock with a porphyritic structure, which is relatively strong and can be used as building materials. The phenocrysts are generally composed of alkaline feldspar or quartz, and the matrix is fine grains or cryptocrystals. Part of porphyry belongs to extruded rocks in igneous rocks, but generally belongs to diagenetic rocks in igneous rocks. Eruption rock is formed by condensation of volcanic magma after it is ejected. As it cools quickly after ejection, many fine particles are formed; diagenetic rock is formed by condensation of volcanic magma intruding into the shallow layer of the crust, and there are many crystal spots.