Kaolinite is a mineral from the group of aluminosilicates. He is not only beautiful, but also very useful. Today, this miracle mineral is widely used in the construction, pulp and paper, food industry, as well as in pharmaceuticals, cosmetology and dentistry. You will find detailed information on the application, varieties and properties of the kaolinite mineral in our article.
Stone from the High Hill
This soft mineral with earthy shine is ubiquitous on our planet. But for the first time it was discovered by the Chinese near a village located on a high gentle hill. The village was called Kao-Ling, which is translated from Chinese as “High Hill”. By the way, the term “clay” also comes from here. When exactly the kaolinite mineral was discovered by the Chinese is unknown. However, Europeans learned about its existence only in the century before last.
Mineral kaolinite belongs to the class of aqueous aluminum silicates. Its formula is as follows: Al 4 [Si 4 O 10 ] (OH) 8 . The chemical composition of kaolinite is as follows:
- Silicon dioxide - 47%.
- Alumina - 39%.
- Water - 14%.
It is necessary to distinguish between the concepts of "kaolinite" and "kaolin." The first is a mineral, and the second is rock. Kaolinite is the main component of most clays.
Physical and chemical properties of the mineral
Kaolinite, as we have already found out, is a clay mineral that in nature forms dense finely dispersed geological masses. We list its main mechanical, physical and chemical properties and features:
- Hardness: 1.5-2 points (on the Mohs scale).
- Density: 2.6-2.7 g / cm 3 .
- Refractive Index: 1.56.
- Shine: dull, earthy.
- Kink: conchoidal.
- Mineral color: grayish, greenish, white, brown, pale yellow (thin scales may have a pearly tint).
- Trait color: White.
- Mineral kaolinite crystallizes in triclinic syngony.
- The piece is opaque, but the individual plates are translucent.
- To the touch - bold.
- It absorbs moisture well.
- When heated to 500 degrees, it loses water, and at 1000-1200 degrees it decomposes with the release of heat.
- It is soluble in sulfuric acid.
Deposits and Production
Kaolinites occur both within the continental crust and in the zone of the ocean floor. The mineral is formed during the so-called kaolinization process, which is accompanied by chemical weathering and hydrothermal alteration of feldspars and other silicates.
Mineral kaolinite is part of various clays, marls and shales. Its largest deposits are located in the southeastern part of China. High-quality kaolins are also mined in Russia (Ural), Ukraine (Zhytomyr, Kiev and Ternopil regions), Great Britain (Cornwell), Germany (Meissen, Halle), Czech Republic (Siedlec), Uzbekistan, Kazakhstan and Bulgaria.
It is worth noting that the process of extracting kaolin from the earth's crust is not particularly costly. They are mined mainly by the open (career) method. So, for example, a clay quarry in Ukraine looks like (Terebovlya city, Ternopil region):
But this kind (photo below) has already mined and crushed kaolinite in Spain.
The history of the use of the mineral
As mentioned above, there is no information about how long ago the Chinese discovered kaolinite. But they were the first to do it. At least this is evidenced by the highest quality of ancient Chinese porcelain. As far back as the third century BC, Chinese craftsmen created their own unique "Terracotta Army", consisting of eight thousand clay statues of warriors and horses.
The technology for processing kaolinite into “white gold” has long been kept secret by the masters of the Middle Kingdom. In Western Europe and in Russia, porcelain learned to make only in the XVIII century. The first factories grew up in German Meissen and French Sevres. In 1744, the Imperial Porcelain Factory, which has been operating to this day, was founded in St. Petersburg.
Mineral kaolinite: application today
It is easy to guess that the main consumer of this mineral is the porcelain and ceramic industries. It is worth noting that the manufacture of high-quality porcelain is a rather complicated and troublesome process. Fortunately, the stone itself is not uncommon and easy to mine. Porcelain is made from refined kaolinite. Previously, it is eliminated from various impurities in centrifuges and hydrocyclones. After this, the raw materials are dehydrated in order to reduce weight and increase the strength of the final product.
In addition, the mineral kaolinite is also used in the production of coated paper, art glaze, toothpaste. Based on kaolin wool , industrial filters, electrical insulating gaskets, as well as heat-insulating materials are made. In addition, kaolins (white clay) are widely used in cosmetology and traditional medicine. Thus, the volumes of kaolinite consumption in the modern world are quite substantial.
The main types of mineral
In fact, by kaolinites, geologists mean a rather large group of various minerals. The most common among them are:
- Rodalite.
- Terratolite.
- Kaffekelit.
Rodalite is a pink-tinted mineral due to iron impurities. It is obtained in Northern Ireland. Terratolite is a mixture of quartz, mica, limonite and, in fact, kaolinite. The color of the mineral is blue-violet. Kefekelit contains impurities of halloysite and some other clay minerals and has a greenish-yellow hue. In China, there are also deposits where a mixture of kaolinite with dickite, quartz and cinnabar is mined. This mineral has a specific name - “chicken blood”.
It will be useful to note that some varieties of kaolinite are quite beautiful. Therefore, they are actively used in decorating furniture and inlaid jewelry.
The healing properties of kaolin
Clay is often called a "natural healer", as well as a "remedy for a hundred diseases." After all, it contains a large number of trace elements useful to the human body. This is magnesium, calcium, potassium, iron, nitrogen, etc. But the most important thing is that all these trace elements and substances in kaolins are present in combinations and ratios that are optimal for humans.
Some clays have radioactive elements, such as radium. But as a rule, their percentage in the breed does not exceed permissible norms. A high degree of radioactivity is characteristic only for those clays that occur in contaminated industrial areas.
Clay in cosmetology and traditional medicine
All cosmetologists are aware of the healing properties of the so-called white clay. The latter acts as an absorbent: cleanses the skin, removing toxins and toxins from it. After clay masks, the skin looks fresher and healthier, small wounds are tightened and scars heal. Kaolin has a beneficial effect on the hair, preventing their fragility.
In folk medicine, clay helps with sore throat and headache. For this, a thin layer is applied to sore spots. Some healers are convinced that kaolin can heal a person from such serious ailments as arthritis and pneumonia. Dental powder is also made from white clay. In case of gastrointestinal upsets, flatulence, alcohol poisoning, clay is taken orally (of course, in small quantities).
Finally…
Kaolinite, although a cheap, but at the same time incredibly useful mineral. After all, it is used in a wide variety of fields and industries. So, it is used in the manufacture of porcelain and ceramics, paper and filters, medicines and food additives. The healing properties of this mineral are widely used for cosmetic and medical purposes.