Granite (Italian granito, from Lat. Granum — grain) — acidic intrusive igneous rock. It consists of quartz, plagioclase, K-feldspar and mica — biotite and / or muscovite. Granites are very common in the continental crust. Extrusive equivalents of granite — rhyolite. The density of granite — 2600 kg / m ³, the compressive strength of 300 MPa.
According to the features of the mineral composition of the granites are the following varieties:
Plagiogranite — light gray granite with a strong predominance of plagioclase in the absence or low content of sodium- potassium- feldspar granites imparts a pinkish — red color.
Alaska — pink granite with a strong predominance of potassium sodium feldspar with a small amount (biotite ), or the lack of mafic minerals .
On the structural and textural features are the following varieties:
Porphyritic granite — contains phenocrysts of isometric or elongated , more or less significantly different in size from the bulk ( sometimes reach 10-15 cm) and is usually represented by orthoclase or microcline , rarely quartz. Porphyritic granites, in which grains of sodium- potassium feldspar pink grows in light gray plagioclase , buying a round shape , called rapakivi granite . This structure facilitates the rapid destruction of the breed , its crumbling . Hence the name . Translated from Finnish rapakivi means » rotten stone «.
Granite is one of the most dense , hard and tough rocks. It is used in construction as a cladding material . Moreover , granite has low water absorption and a high resistance to frost and dirt . That is why it is ideal for paving both indoors and outdoors. However, it is worth remembering that such placement will have a slightly higher background radiation , and therefore is not recommended stoning some types of granite accommodation . Moreover , some types of granite considered as promising materials for the production of natural uranium. The interior of the granite is also used for the walls , stairs, countertops and creating columns , ornaments stair balusters made of granite , creating vases , tiled fireplaces and fountains. The exterior granite is often used as cladding , construction ( rubble stone for foundations , fences and retaining walls ) or masonry material (stone blocks , breccia ) . Granite is also used in monuments and granite rubble . First mined in open pits block , the second — on the crushed stone .