Editing Hydrocarbon (section)

==Origin==
[[File:Korna natural oil seep 1.JPG|thumb|upright=1.2|Natural oil spring in [[Korňa]], [[Slovakia]]]]

The vast majority of hydrocarbons found on [[Earth]] occur in [[crude oil]], petroleum, [[coal]], and natural gas.  For thousands of years they have been exploited and used for a vast range of purposes.<ref name ='van Dijk_2022, n'>van Dijk, J.P. (2022); Unravelling the Maze of Scientific Writing Through the Ages: On the Origins of the Terms Hydrocarbon, Petroleum, Natural Gas, and Methane. Amazon Publishers, 166 pp. PaperBack Edition B0BKRZRKHW.  {{ISBN|979-8353989172}}</ref> Petroleum ({{lit|rock oil}}) and coal are generally thought to be products of decomposition of organic matter.  Coal, in contrast to petroleum, is richer in carbon and poorer in hydrogen. Natural gas is the product of [[methanogenesis]].<ref>Clayden, J., Greeves, N., et al. (2001) ''Organic Chemistry'' Oxford {{ISBN|0-19-850346-6}}, p.&nbsp;21.</ref><ref>McMurry, J. (2000). ''Organic Chemistry'' 5th ed. Brooks/Cole: Thomson Learning. {{ISBN|0-495-11837-0}}. pp.&nbsp;75–81.</ref>

A seemingly limitless variety of compounds comprise petroleum, hence the necessity of refineries. These hydrocarbons consist of saturated hydrocarbons, aromatic hydrocarbons, or combinations of the two.  Missing in petroleum are alkenes and alkynes.  Their production requires refineries. Petroleum-derived hydrocarbons are mainly consumed for fuel, but they are also the source of virtually all synthetic organic compounds, including plastics and pharmaceuticals.  Natural gas is consumed almost exclusively as fuel. Coal is used as a fuel and as a reducing agent in [[Steelmaking|metallurgy]].

A small fraction of hydrocarbon found on earth, and all currently known hydrocarbon found on other planets and moons, is thought to be [[Abiogenic petroleum origin|abiological]].<ref>{{cite journal |doi=10.2138/rmg.2013.75.14 |title=On the Origins of Deep Hydrocarbons |year=2013 |last1=Sephton |first1=M. A. |last2=Hazen |first2=R. M. |journal=Reviews in Mineralogy and Geochemistry |volume=75 |issue=1 |pages=449–465 |bibcode=2013RvMG...75..449S}}</ref>

Hydrocarbons such as ethylene, isoprene, and monoterpenes are emitted by living vegetation.<ref>{{cite web |last1=Dewulf |first1=Jo |title=Hydrocarbons in the Atmosphere |url=https://www.eolss.net/Sample-Chapters/C06/E6-13-02-07.pdf |access-date=26 October 2020}}</ref>

Some hydrocarbons also are widespread and abundant in the [[Solar System]]. Lakes of liquid methane and ethane have been found on [[Titan (moon)|Titan]], [[Saturn]]'s largest moon, as confirmed by the ''[[Cassini–Huygens]]'' space probe.<ref>[http://www.jpl.nasa.gov/news/news.php?release=2013-364 NASA's Cassini Spacecraft Reveals Clues About Saturn Moon]. {{webarchive|url=https://web.archive.org/web/20140902080814/http://www.jpl.nasa.gov/news/news.php?release=2013-364 |date=2 September 2014 }}. NASA (12 December 2013).</ref> Hydrocarbons are also abundant in nebulae forming [[polycyclic aromatic hydrocarbon]] compounds.<ref>{{cite journal |doi=10.1093/mnras/stu454 |arxiv=1403.1856 |title=PAH formation in O-rich planetary nebulae |journal=Monthly Notices of the Royal Astronomical Society |volume=441 |issue=1 |pages=364–377 |year=2014 |last1=Guzman-Ramirez |first1=L. |last2=Lagadec |first2=E. |last3=Jones |first3=D. |last4=Zijlstra |first4=A. A. |last5=Gesicki |first5=K. |doi-access=free |bibcode=2014MNRAS.441..364G |s2cid=118540862}}</ref>