Granite granite is a plutonic acid igneous rock formed by the condensation of magma in the deep underground, and some granites are gneiss or migmatized rocks formed by the metamorphism of magma and sedimentary rocks. Granite is mainly composed of feldspar, quartz, black and white mica, with quartz content of 10%~50%. The content of feldspar is about 2/3 of the total amount, which is divided into orthoclase, plagioclase (alkali lime) and microcline (potash). The mineral compositions of different varieties are different, and there may also be pyroxene and hornblende. Granite is hard and hard to be eroded by acid, alkali or weathering. It is often used as building material. Granite is derived from the Latin word granite, while the Chinese word granite was translated from Japanese. The dictionaries and geological books in the early Meiji period translated Granite into granite or granite. Flower describes that this kind of rock has beautiful stripes. Gang or Gang means that this kind of rock is very hard, which means a hard rock with flower like stripes. Chinese scholars continue to use this translation.
Granite is hard and dense, with high strength, weathering resistance, corrosion resistance, abrasion resistance and low water absorption. Its beautiful color can be preserved for more than 100 years. It is a good building material, but it is not heat-resistant. Granite stones are classified into different grades according to color, pattern, luster, structure, material and other factors. The mineral bureau of Taiwan's Ministry of Economy classifies granites into six types: black, brown, green, gray white, light red and dark red. Granite is a good building material, but some areas of granite will overflow radon, a natural radioactive gas. Radon can make people suffer from lung cancer, and 13% of lung cancer deaths in Hong Kong are caused by excessive radon. Coarse or medium grained intrusive rocks rich in quartz and feldspar are the most common plutonic rocks in the crust, which are formed by the cooling of magma in the deep crust. Because it can be used as paving stone and building stone, granite mining was once an important industry. Granite can occur as dyke or bedrock, and more representative is irregular rock mass with great scale change. The main component is feldspar, plagioclase and alkali feldspar are generally rich, and the relative abundance of the two forms the basis for the classification of granites. In most granites, the ratio of two types of feldspar here is less than 1/2. This category includes most granites in the eastern, central, and southwestern United States, southwestern England, Baltic Haiti Shield, western and central France, Spain, and many other regions. Plagioclase is a kind of granite that greatly exceeds alkaline feldspar and is common in some areas of western United States. The granite with alkali feldspar content much more than plagioclase occurs in many places in New England, England and Oslo, Norway, but it is a small rock body, which is widely developed in northern Nigeria. The rock containing less than 20% quartz is not called granite, and the maximum content of dark minerals (ferromagnesian minerals) is about 20% (by volume). The less main minerals in granite are muscovite, biotite, hornblende, pyroxene or rare forsterite. Biotite can occur in any type of granite and is usually present, although sometimes in small amounts. Sodium bearing hornblende and pyroxene (riebeckite, riebeckite, aegirine) are unique to alkaline granite. If neither of the two types of feldspar has much more content than the other, then hornblende and pyroxene are unlikely to be the main minerals; Dark minerals are usually biotite or muscovite, or both.