How Are Porphyry Rocks Formed
Porphyry is a kind of igneous rock with porphyritic structure.Porphyrites are generally composed of alkaline feldspar or quartz with a fine grain or cryptocrystalline matrix (vitreous).
It is a general term for extruded rocks, epi-diagenetic rocks and ultra-epi-diagenetic intrusive rocks with potassium feldspar, accessory feldspar or quartz as porphyrites.
Porphyry, purplish red, originally referred to any igneous rock with porphyry crystals.First used of a purplish red rock with alkaline feldspathic crystals from Egypt.Some people thought it was synonymous with porphyrite.Usually refers to the alkali feldspar as porphyry matrix for fine grain or cryptocrystalline extrusive rocks and epidiagenetic rocks.
Generally refers to the alkali feldspar or quartz as porphyry ejected rocks and epidiagenetic rocks, the matrix for fine grain or cryptocrystalline - vitreous.Extrusive rocks can be divided into rhyolitic porphyry, trachyporphyry, leucite porphyry, etc.Epidiagenesis can be divided into quartz porphyry, granite porphyry, syenite porphyry and so on.The term porphyry originally refers to igneous rocks with porphyry crystals or porphyritic structures;The matrix composition can be described as granite porphyry and diorite porphyry.
Porphyritic structure refers to the two parts of porphyritic minerals and fine or cryptocrystalline matrix which can be obviously separated into coarse grains.Intermediate and acidic rocks, such as quartz porphyry and granite porphyry, with quartz and alkaline feldspar as porphyrites;The basic or ultrabasic vein rocks with dark minerals such as biotite and amphibole as porphyrites are called lamprophyres.Porphyrite plagioclase to the porphyry in the middle, the basic porphyrite known as porphyrite.Porphyry and porphyrite are the crystallization products of magma in two stages.Porphyry is the crystallization of magma in the deeper part of the ground in the early stage, and the matrix is the product of the crystallization in the shallow part of the crust in the late stage.Porphyry and porphyrite are related to minerals such as copper, molybdenum, tungsten and iron deposits.Porphyry and porphyrite are distinguished only in China, but not in foreign countries.