Lignite - fossil coal containing up to 78% carbon. It seams among sedimentary rocks, formed from plant debris. In brown coal, clay substance is usually found as an impurity, which increases its ash content. It can ignite spontaneously. Its calorific value is lower than that of coal (6000 kcal/kg), but nevertheless it is used as fuel or as a raw material for the production of combustible fuel and other chemical products. A type of brown coal with a clearly visible structure of the remnants of wood is called lignite. It is most often found in deposits of young geological systems. Almost all lignite goes to thermal power plants. In Russia, brown coal is mined in the following basins: Moscow Region, Chelyabinsk, Kansk-Achinsk, Lensky. Mining abroad is conducted in Germany, the Czech Republic (Ostrava-Karvinsky basin).
Peat - is a dark brown mass consisting of semi-decomposed plant debris. It is formed in swamps and overgrown reservoirs. Its carbon content is up to 60%. Peat is used as cheap fuel; heat-insulating plates, acetic acid are produced from it. It is also widely used to fertilize fields. In Russia, peatlands occupy large areas, especially in the forest zone. Tuffs are rocks of various origins.
Tufa - is a porous rock formed as a result of precipitation of calcium carbonate from sources. Such tuff is used to produce cement and lime. Volcanic tuff - cemented volcanic ash. Tuffs are used as a building material. It has different colors.
Mica - rocks with the ability to split into the thinnest layers with a smooth surface; in the form of impurities found in sedimentary rocks. Various mica is used as a good electrical insulator, for the manufacture of windows in metallurgical furnaces, in the electrical and radio industries. In Russia, mica is mined in Eastern Siberia, in Karelia. Industrial development of mica deposits is carried out in Ukraine, the USA, Brazil.
Marble - is a crystalline rock formed as a result of limestone metamorphism. It comes in a variety of colors. Marble is used as a building material for wall cladding, in architecture and sculpture. In Russia, there are many of its deposits in the Urals and the Caucasus. Abroad, marble mined in Italy is most famous.
Asbestos (Greek: unquenchable)- is a group of fibrous fireproof rocks that are split into soft fibers of greenish-yellow or almost white color. It lies in the form of veins (a vein is a mineral body that fills a crack in the earth’s crust, usually has a plate-like shape, going vertically to great depths. The length of the veins reaches two or more kilometers), among igneous and sedimentary rocks. It is used for the manufacture of special fabrics (fire insulation), tarpaulins, fireproof roofing materials, as well as heat-insulating materials. In Russia, asbestos is mined in the Urals, in the Sayan Mountains, abroad - in China and other countries.
Asphalt (resin) - is a brittle resinous rock of brown or black color, which is a mixture of hydrocarbons. Asphalt melts easily, burns with a smoky flame, is a product of a change in some types of oil, of which some of the substances have evaporated. Asphalt often permeates sandstones, limestones, marl. It is used as a building material for paving roads, in electrical engineering and the rubber industry, for the preparation of varnishes and mixtures for waterproofing. The main asphalt deposits in Russia are in the Ukhta region, and abroad - in Venezuela, France, Jordan, and Israel.
Potash salts - sedimentary rocks consisting of minerals containing potassium - sylvine, Cainite and others. The most common potassium salts are carnalite, cainite. The largest field in Russia is Solikamskoe (Ural). Potash salts are used to produce potash fertilizers. The extraction of these salts is carried out in the west of Ukraine, in Kazakhstan, Belarus, Germany, Poland, France, the USA, Canada and in many other countries of the world.
Apatity - minerals rich in phosphoric salts of green, gray and other colors; found among various igneous rocks, sometimes forming large clusters. Apatites are mainly used for the production of phosphate fertilizers, they are also used in the ceramic industry. In Russia, the largest deposits of apatites are located in the Khibiny, on the Kola Peninsula. Abroad they are mined in Sweden, Spain, and the Republic of South Africa. Phosphorites are sedimentary rocks rich in phosphorus compounds that form grains in a rock or bind various minerals into a dense rock. The color of phosphorites is dark gray. They are used, like apatites, to obtain phosphate fertilizers. In Russia, phosphorite deposits are common in the Moscow and Kirov regions. Abroad they are mined in the United States (Peninsula Florida) and North Africa.