White Marble عرض1 month ago - ملابس وموضة - الجوف - 30 الآراء
Marble is a rock widely used in buildings, monuments, and sculptures. It consists chiefly of calcite or dolomite, or a combination of these carbonate minerals. Marble is a type of metamorphic rock formed from limestone. Marble is found in many countries, including Belgium, France, Great Britain, Greece, India, Italy, and Spain.
Marble is formed from limestone by heat and pressure in the earth’s crust. These forces cause the limestone to change in texture and makeup. This process is called recrystallisation. Fossilised materials in the limestone, along with its original carbonate minerals, recrystallise and form large, coarse grains of calcite. Impurities present in the limestone during recrystallisation affect the mineral composition of the marble that forms. The minerals that result from impurities give marble a wide variety of colours. The purest calcite marble is white. Marble containing hematite has a reddish colour. A marble that has limonite is yellow, and marble with serpentine is green.
Marble does not split easily into sheets of equal size and must be mined carefully. The rock may shatter if explosives are used. Blocks of marble are mined with channelling machines, which cut grooves and holes in the rock.
Extremely pure calcite marble is used for most statues. Large blocks of coloured marble are, used for columns, floors, and other parts of buildings. Smaller pieces of such marble are crushed or finely ground and used as abrasives in soaps and other products. Crushed or ground marble is also used in paving roads and in manufacturing roofing materials and soil treatment products.
How is marble formed
Its characteristic purity, devoid of any impurity and residue, spontaneously raises a series of questions such as what kind of rock is marble and how is marble formed? Well, marble is the result of a recrystallization of carbonate minerals present within sedimentary rocks. Generally, these rocks are formed by processes of regional metamorphism which, thanks to high temperature and pressure, tends to increase the grain of the crystals, giving the marble its typical saccharoid appearance. Consequently, this gives rise to a mosaic of calcite or dolomite crystals which is progressively deprived of any fossil, stratification or sedimentary structure present at the beginning: this is how natural marble rock is formed and from what derives its classic clarity.
Where is marble found
Marble is generally discovered in massive seams in many parts of the world. Yet, where is marble found to a greater extent? Well, although marble can be found in many countries, four main countries hold almost half of the marble in the world: Italy, China, India and Spain. Apart from these four, also Greece, Turkey and United states have their marble quarries. In Tuscany there are probably the most famous and precious types of marble, such as Carrara and Calacatta. These Italian marble stones are unanimously considered among the finest and more luxurious varieties, emblem of marble par excellence.
Types of marble
Based on the composition, it is possible to draw up a first categorization of the different types of marble:
Crystalline limestone marbles: these are pure marbles (i.e. without fossils) and generally composed of larger crystals. You can find them both white and colored.
Cryptocrystalline limestone marbles: their crystalline structure is less marked than the previous type of marble and they are generally quite colorful.
Clastic marbles: fragments of rocks, cemented fossils as well as siliceous or calcareous materials are visible in the texture.
Serpentine marbles: green colored marbles whose name derives from a particular group of minerals called the serpentine group which is mixed with limestone. Sometimes, it is possible to find them in darker shades close to blue or yellow based on which mineral of serpentine group is present in the majority within the marble.