Coal is a black or brownish-black, combustible sedimentary rock, with 30 % (lignite) to 98 % (anthracite) carbon by weight, mixed with various amounts of water and small amounts of sulfur and nitrogen compounds. It is formed from plant matter that decayed in swamps and bogs that has been compressed and altered by geological processes over millions of years. Coal is primarily used as a fuel.
Generalic, Eni. "Coal." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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Periodic Table