Granite

Classification：Igneous Rock

A common intrusive rock consisting mainly of feldspar and quartz, the main component of the continental crust. Some high-grade metamorphic rocks similar in composition are sometimes referred to as granite.

Granite belongs to intrusive rocks in acidic (SiO2>66%) magmatic rocks. This is the most common rock in this category, mostly shallow flesh red, pale gray, gray white. Medium coarse grain, fine grain structure, massive structure. Some of them are spotted, spherical, and flax like structures. The main minerals are quartz, potash feldspar and acid plagioclase. The secondary minerals are biotite, hornblende, and sometimes a small amount of augite. Many species are common accessory minerals, magnetite, sphene, zircon, apatite, tourmaline, fluorite etc.. Quartz content is the largest in all kinds of magmatic rocks. Its content can range from 20 to 50%, and a few can reach 50 to 60%. The content of potassium feldspar is generally more than that of plagioclase. The proportion of the content of the two is usually 2/3 of the total feldspar, 1/3 of the plagioclase, and most of the potassium feldspar in Granite is pale red and gray and gray. Gray potassium feldspar and plagioclase are not easy to distinguish from hand specimens. At this time, we should carefully observe the bimorst characteristics of these two feldspar, because the plagioclase has a polycrystalline double crystal, and when the hand specimen is turned, we can see that there is a regular dark and dark interphase on the plagioclase crystal, and the potassium feldspar is a double crystal with a different brightness.

Granite can also be named for dark minerals, such as dark mica, which is called black mica Granite, which is a common kind of Granite. If the content of black mica and Muscovite is nearly equal, it can be called two mica Granite. If dark minerals are mainly hornblende, it is called hornblinde Granite. If dark minerals are mainly pyroxene, it is called pyroxene Granite, and almost no dark minerals can be called white granite.