Limestone - natural stone, which is a soft sedimentary rock of organic or organic-chemical origin composed mainly of calcium carbonate (calcite).Often it includes impurities of quartz, phosphate, silica, clay and sand particles, as well as the remains of calcareous skeletons of microorganisms.In this article, we consider this a natural material, its types, properties and scope, as well as find out what is the chemical formula of the limestone, and much more.
Formation limestone
First, let's look at how these minerals were formed.Limestone is mainly formed in a shallow marine basin, although there are freshwater.It occurs in the form of deposits and formations.Sometimes it is deposited, like gypsum and salt from evaporating sea water lagoons and lakes.However, most of it is deposited in the seas that have not experienced an intensive drying.Most limestone formation began with the separation of living organisms from sea water to build calcium carbonate skeletons and shells.These remnants of dead organisms accumulate in large quantities on the seabed.The most striking example of extraction and accumulation of calcium carbonate are coral reefs.Thus, in some cases, to break limestone can be seen separate sinks.Under the influence of sea currents and by the impact of the waves and surf reef break.And on the seabed to the limestone fragments added calcium carbonate, which precipitates out of the water saturated with them.Also in the education of young limestone rocks involved calcium, which comes from the destroyed ancient rocks.
Varieties There are many kinds of limestone.Coquina is called accumulation of shells and their fragments, cemented in a honeycomb formation.In the case where the shells have a very small amount, it forms a soft, loosely, anointing, fine crumbling limestone - chalk.Oolitic rock consists of tiny, about the size of the fish eggs cemented balls.The core of each can be represented by the fragment of the shell, any grain of sand or other foreign material particle.In the case when the beads are larger, such as pea, they are called pizolitami and breed respectively pizolitovym limestone.Another kind is a travertine - it is formed on the surface during the precipitation of aragonite or calcite carbonate from water sources.If such deposits are highly porous base (spongy), it is called tuff.Unconsolidated mixture of clay and calcium carbonate be called marl.
In addition, limestone may vary and colors.Basic color - white.But it can also be yellow, light beige, light gray, at least - slightly pinkish.White-pink and white-yellow rock are considered the most valuable.
Formula limestone
As mentioned earlier, this natural material is composed mainly of calcite or calcite skeletons and remains of shells, rarely of aragonite.Hence, the formula of limestone will be as follows: CaCO3.However, pure breed is extremely rare, in some cases it includes various impurities of quartz, clay minerals, dolomite, gypsum, pyrite, and, of course, organic residues.Thus, dolomitic limestone (Formula this species includes MgO) comprises from four to seventeen percent magnesium oxide, marly - up to 21 percent of acid oxides (SiO2 + R2O3).The composition may include carbonate dolomite CaMg (CO3) 2, FeCO3 and MnCO3, in small quantities - oxides, sulphides and hydroxides of Fe, Ca3 (PO4) 2, CaSO4.
Limestone: properties and applications
physical and mechanical properties of the rocks are extremely heterogeneous, however, depends on its texture and structure.High school students consider the properties of limestone (4 class) from the position of its external characteristics.They study the following parameters: color, density, strength, a condition solubility.We'll go a little further and consider in greater depth the properties of minerals.Limestone has a density in the range 2700-2900 kg / m3.This variation is explained by the amount of impurities contained quartz, dolomite and other minerals.Volume weight changes on a much larger range.So, travertine and shell it is only 800 kg / m3, while the crystalline rocks reaches 2800 kg / m3.Considering the properties of limestone, it should be noted that the compressive strength of the rock depends on its bulk density.So Coquina it is only 0.4 MPa, while afanitov close to 300 MPa.The above characteristics of the breed and use of these defined materials.For example, in the construction of a more dense limestone used in masonry walls and porous good for lining and create decorative ensembles.
impact of climate
Depending on the humidity level, the properties of limestone are subject to change.This primarily affects its strength - it significantly reduced, if the stone is wet.Moreover, most fields has a mixed breed.At this point it is worth paying attention, because inhomogeneous material density will vary, which in turn can lead to destruction.Analyzing the properties of limestone, should not be neglected, and parameters such as frost: it significantly affects the strength of the minerals and the duration of its use.So, crystalline limestones frost is 300-400 cycles.However, this rate is significantly reduced in the presence of cracks and pores in the material.Thus, all the above-mentioned properties of limestone must be considered when using this natural material in order to prevent its destruction.
Limestone construction
The construction industry is a major consumer of minerals under consideration.Dolomite (rock) limestone used for the production of putty and plaster mixtures, sealants and other things.White limestone is used in large quantities in the finishing and decoration of buildings.Coquina is often found as building blocks, and so on. D. We will not focus on this industry, and it is so widely known to all.And therefore go further.
Limestone in modern industrial production
turns this natural material used in the manufacture of paints, rubbers and plastics.A purified of impurities harmful to human body, is used even in food industry.Production of glass is not possible without limestone, because it is the main source of calcium.This breed has become indispensable, and most importantly - affordable component for the production of paper.In everyday life we constantly use products such as pipes, linoleum, tile, tiles, etc.., And had no idea that all these objects is also present limestone.Even the production of plastic (PP, PVC, krempleny lavsan, etc.) is complete without this material.The paints calcium carbonate is used as a coloring pigment.As you can see, this material occupies a leading position in almost all industries.
Chemical Industry
Even things like shoe polish, toothpaste, scouring powder, etc. That we use every day are derived from limestone.This raw material is used in the manufacture of drugs used for the protection of the environment from various types of pollution.Based on the foregoing, we can safely say that the well-known and readily available material, which is limestone, is an essential element of modern civilization.
Interesting facts
great contribution to the development of stone carving made the peoples of South and Central America.The Olmecs, Aztecs, Mayans have made significant progress in the ability to produce chalcedony, obsidian and silicon steel, cutting tools and other household items.So, rolling pins, graters, mortars and other created them from the basalt, sandstone and limestone.Drums and chopping tools made of diorite, jadeite, jade and other materials.The main center for stone processing are considered to be the city of the Maya - The fineness and Nebaj.
