Granite and Marble
Granite is one of the most popular magma rocks in nature. It constitutes 95% of the volume of all intrusive rocks. It contains quartz, orthoclase, biotite and other minerals. Granite is one of the most dense and hard rocks, it also has low water absorption capacity and high resistance to cold. It is therefore suitable for indoor and outdoor furnishing, for construction and tiling of walls, floors, stairs, columns, etc.
Granite - the most widespread acid to ultra acid rock, built up of almost equal amounts of potassium feldspar (microcline and orthoclase), acid plagioclase (albite, oligoclase, oligoclase-andesite) and quartz. Its composition includes non-ferrous minerals (10-15%) as biotite, muscovite, amphibole, and more rarely pyroxene. Depending on the size of the mineral grains granite can be coarse-granular, medium-granular, or fine-granular. It has porphyritic texture; hypidiomorphic-granular texture. Varieties: two-mica, biotite-granite, amphibole granite, augite granite, alaskite and others. Granitic magma is formed under magmatic differentiation or by anatexis and granitization (in Precambrian granite). Granites usually form large batholiths, stocks and laccoliths. The density of granite is 2590-2670 kg/m3; humidity absorption 0.8%; impact strength of 120-242 MPa. Water- and thermal resistant. It can withstand heating of up to 570 C. It splits in all directions and can be polished. It is widely used in the field of industry (due to the rigidness and the thermal resistance) and in construction for coatings, decorative pavements and cobbles.
Marble is a metamorphic rock built up of calcium or dolomite (the last two are called dolomitic marbles). Colour ranges from pure white to all shades of colours. Marble rocks are formed when metamorphism of limestone and dolomite takes place.
- Major European deposits: Italy, Greece, France and Norway.
- In Bulgaria, marble is extracted in the Rila, Rhodopes, Strandzha, Pirin and Berkovska mountains.
- Application: in the household - for tiling, mosaics, production of cement and limestone. It is also used in sculpture, in refractory, glass and metallurgical industries.