Coal: Formation,Types of Coals & Production


  • Coal is a flammable black hard rock used as a solid fossil fuel and often Known as “Black Gold” or “Black diamond”.

  • It is mainly made up of 65 – 95% carbon and also contains hydrogen, sulphur, oxygen and nitrogen.

  • It is a sedimentary rock formed from peat, by the pressure of rocks laid down later on top.

  • The harder forms of coal, such as anthracite, are metamorphic rocks because they were changed by higher temperature and pressure.

Coal formationTypes of Coals:

Under suitable conditions, plant material is transformed step by step into

1. Peat

  • Contains less than 40 to 55 % carbon.

  • In its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water

  • It is also used as a conditioner for soil to make it more able to retain and slowly release water.

2. Lignite

  • Also known as brown coal and it is the lowest rank of coal.

  • It is used as fuel for electric power generation.

  • Jet is a compact form of lignite that is sometimes polished and has long been used as an ornamental stone.

3. Sub-bituminous coal

  • It is used as fuel for steam-electric power generation.

  • Also, it is a source of light aromatic hydrocarbons for the chemical synthesis industry.

4. Bituminous coal

  • It is a dense rock, black but sometimes dark brown.

  • It is a relatively soft coal that breaks and burns readily and quickly.

  • It used as fuel in steam-electric power generation, and for heat and power applications in manufacturing; also and to make coke

5. Steam coal

  • It was once widely used as a fuel for steam locomotives.

  • In this specialized use it is sometimes known as sea-coal in the U.S.

  • Small steam coal (dry small steam nuts or DSSN) was used as a fuel for domestic water heating

6. Anthracite

  • It is the highest quality: a harder, glossy, black coal.

  • It is longer burning, and used mainly for residential and commercial space heating.

Other facts about coal:

  • Graphite is difficult to ignite and is not so commonly used as fuel: it was mostly used in pencils and, when powdered, as a lubricant.

  • Diamond is commonly believed to be the highest grade, but this is not true. Diamond is carbon but is not formed from coal.

  • Coal contains impurities. The particular impurities determine the use. Coking coal has little ash or sulfur or phosphorus. Those would spoil the iron made by the blast furnace.

Formation of Coal:

  • At various times in the geologic past, the Earth had dense forests in low-lying wetland areas.

  • Due to natural processes such as flooding, these forests were buried underneath soil.

  • As more and more soil deposited over them, they were compressed. The temperature also rose as they sank deeper and deeper.

  • As the process continued the plant matter was protected from biodegradation and oxidation, usually by mud or acidic water.

  • This trapped the carbon in immense peat bogs that were eventually covered and deeply buried by sediments.

  • Under high pressure and high temperature, dead vegetation was slowly converted to coal. As coal contains mainly carbon, the conversion of dead vegetation into coal is called carbonization.

  • The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, although coal is known from most geological periods.

  • The exception is the coal gap in the Permian–Triassic extinction event, where coal is rare.

  • Coal is known from Precambrian strata, which predate land plants — this coal is presumed to have originated from residues of algae.

Coal mining around the WorldList of countries by coal production

This is a list of countries by coal production in 2014, based mostly on the Statistical Review of World Energy published in 2015 by British Petroleum, ranking countries with coal production larger than 10 millions tonnes. Shares are based on data expressed in tonnes oil equivalent.


Rank Country/Region Coal production
(million tonnes)
Share of
Total (%)


1 China


2 United States


3 Australia


4 India


European Union


5 Indonesia


6 Russia


7 South Africa


8 Germany


9 Poland


10 Kazakhstan




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