Coal

Coal is a combustible black or brownish-black sedimentary rock, formed as layers called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. It is a fossil fuel, formed when plants decay into peat which is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits formed from wetlands called coal forests that covered much of the tropics during the late Carboniferous and early Permian.

thumb|A lump of peat thumb|Peat stacks in Südmoslesfehn (Oldenburg (district)|district of Oldenburg, Germany) in 2013 thumb|Peat gatherers at Westhay, [[Somerset Levels in 1905]] thumb|Peat extraction in East Frisia, Germany in 1987

Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.

Lignite (), often called brown coal, is a soft, brown, combustible sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35% and is considered the lowest rank of coal due to its relatively low heat content. When removed from the ground, it contains a very high amount of moisture, which partially explains its low carbon content. Lignite is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation.

a grey, hard, and porous fuel with high carbon content and few impurities

often greasy, shiny, combustible organic sedimentary rock that consists of more than 75 per cent carbon by weight

mineraloid and minor gemstone

Pneumoconiosis is the general term for a class of interstitial lung disease where inhalation of dust (for example, ash dust, lead particles, pollen grains etc) has caused interstitial fibrosis. The three most common types are asbestosis, silicosis, and black lung disease. Pneumoconiosis often causes restrictive impairment, although diagnosable pneumoconiosis can occur without measurable impairment of lung function. Depending on extent and severity, it may cause death within months or years, or it may never produce symptoms. It is usually an occupational lung disease, typically from years of du

chemical reactions that convert carbon monoxide and hydrogen into liquid hydrocarbons

fuel

chemical mixture

residue of coal combustion

method of production of liquid hydrocarbons for use as synthetic fuel

fine powdered form of coal, which is created by the crushing, grinding, or pulverizing of coal

thumb|Photomicrograph of torbanite, from Bathgate, Scotland Torbanite, also known historically as boghead coal or kerosene shale, is a variety of fine-grained black oil shale. It usually occurs as lenticular masses, often associated with deposits of Permian coals. Torbanite is classified as lacustrine type oil shale. A similar mineral, cannel coal, is classified as being a terrestrial form of oil shale, not a lacustrine type.

land type during the late Carboniferous and Permian times

thumb | right Gyttja (sometimes gytta, from Swedish ) is a mud formed from the partial decay of peat. It is black and has a gel-like consistency. Aerobic digestion of the peat by bacteria forms humic acid and reduces the peat in the first oxygenated metre (generally 0.5 metre) of the peat column. As the peat is buried under new peat or soil the oxygen is reduced, often by waterlogging, and further degradation by anaerobic microbes, anaerobic digestion can produce gyttja. The gyttja then slowly drains to the bottom of the column. It pools at the bottom of the peat column, about below the surfac

bucket for conveying coal to a stove or fireplace

thumb|right|Xylit with wooden structures

Vitrinite is one of the primary components of coals and most sedimentary kerogens. Vitrinite is a type of maceral, meaning organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass (vitreous). It is derived from the cell-wall material or woody tissue of the plants from which coal was formed. Chemically, it is composed of polymers, cellulose and lignin and forms diagenetically by the thermal alteration .

type of bituminous coal

thumb|John Blenkinsop's pioneering locomotive pulling several chaldrons (1813). thumb|Chaldron waggon at Beamish Museum|Beamish. The long brake lever is for control when running down to the [[staith by gravity. Note that the perspective of this photo makes the chaldron seem much larger than it is.]] A chaldron (also chauldron or chalder) was an English measure of dry volume, mostly used for coal; the word itself is an obsolete spelling of cauldron. It was used from the 13th century onwards, nominally until 1963, when it was abolished by the Weights and Measures Act 1963, but in practice until

right|thumb|Leonardite, naturally Redox|oxidized [[lignite, rich in humic acid]]

international agreement

A maceral is a component, organic in origin, of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite, and liptinite.

thumb|100px|Carbolineum thumb|upright|Telephone pole treated with carbolineum in Hawaii Carbolineum is an oily, water-insoluble, flammable, dark brown mixture from coal tar components, smelling of tar. It contains among other things anthracene and phenol.

Charring is a chemical process of incomplete combustion of certain solids when subjected to high heat. Heat distillation removes water vapour and volatile organic compounds (syngas) from the matrix. The residual black carbon material is char, as distinguished from the lighter colored ash. By the action of heat, charring removes hydrogen and oxygen from the solid, so that the remaining char is composed primarily of carbon. Most solid organic compounds, like wood or biological tissue, and thermoset polymers exhibit charring behaviour. In non-scientific terms, charring means partially burning so

series of systems and technologies

lower grade of coal that contains 35–45% carbon

type of coal-based fuel

thumb|The surface of a vitrain fragment isolated from low-carbon coal viewed under a microscope (x2000 magnification) Vitrain is a lithotype of coal formed from the bark of large plants. Known for its glossy appearance, vitrain typically occurs in thin bands, between 3 and 10 millimeters in width. It has a brittle texture and typically forms cubical pieces when broken. Chemically, vitrain stands out among coal lithotypes by hosting large concentrations of germanium. Combustion of vitrain proves a vital source of germanium production, where the element can be extracted from the leftover ash.