What kind of rock is granite

Granite is a magmatic or igneous rock. According to the geological origin, rocks can be divided into three types: igneous rocks, sedimentary rocks and metamorphic rocks. Granite is an igneous rock (magmatic rock), limestone is a sedimentary rock, and marble is a metamorphic rock.

Granite is an intrusive rock in acidic (SiO2>66%) magmatic rocks. Medium-coarse-grained, fine-grained structure, massive structure. There are also some variegated structures, spherical structures, and gneiss-like structures.

The main minerals are quartz, potassium feldspar and acid plagioclase, and the minor minerals are biotite, amphibole, and sometimes a small amount of pyroxene. There are many kinds of accessory minerals, common ones are magnetite, sphene, zircon, apatite, tourmaline, fluorite and so on. The content of quartz is the most among various magmatic rocks, and its content can range from 20-50%, and a few can reach 50-60%. The content of potassium feldspar is generally more than that of plagioclase, and the content ratio of the two is often that potassium feldspar accounts for two-thirds of the total feldspar, plagioclase accounts for one-third, and potassium feldspar is more abundant in granite. It is light red fleshy, and also has grayish white and gray. The off-white kaleidite and plagioclase are often indistinguishable on hand specimens. At this time, we should carefully observe the twin crystal characteristics of these two feldspars, because plagioclase has polycrystalline twin crystals. It is a card-type double crystal, showing two halves of different brightness.