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{{Infobox copper}}

'''Copper''' is a [[chemical element]]; it has [[Chemical symbol|symbol]] '''Cu''' (from [[Latin]] {{lang|la|cuprum}}) and [[atomic number]] 29. It is a soft, malleable, and [[ductility|ductile]] metal with very high [[thermal conductivity|thermal]] and [[electrical conductivity]]. A freshly exposed surface of pure copper has a [[Copper (color)|pinkish-orange color]]. Copper is used as a conductor of heat and electricity, as a [[building material#Metal|building material]], and as a constituent of various metal [[alloy]]s, such as [[sterling silver]] used in [[jewelry]], [[cupronickel]] used to make marine hardware and [[coin]]s, and [[constantan]] used in [[strain gauge]]s and [[thermocouple]]s for temperature measurement.

Copper is one of the few [[native metal]]s, meaning metals that occur naturally in a directly usable, unalloyed metallic form. This led to very early human use in several regions, from {{Circa|8000 BC}}. Thousands of years later, it was the first metal to be [[Smelting|smelted]] from sulfide ores, {{Circa|5000 BC}}; the first metal to be cast into a shape in a mold, {{Circa|4000 BC}}; and the first metal to be purposely alloyed with another metal, [[tin]], to create [[bronze]], {{Circa|3500 BC}}.<ref name="EncBrit">{{cite EB15|1992|3|Bronze|page=612|Copper|isbn=978-0-85229-553-3|oclc=25228234}}</ref>

Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as [[azurite]], [[malachite]], and [[turquoise]], and have been used widely and historically as pigments.

Copper used in buildings, usually for roofing, oxidizes to form a green [[patina]] of compounds called [[verdigris]]. Copper is sometimes used in [[decorative art]], both in its elemental metal form and in compounds as pigments. Copper compounds are used as [[bacteriostatic agent]]s, [[fungicide]]s, and [[wood preservative]]s.

Copper is essential to all [[aerobic organism]]s.  It is particularly associated with oxygen metabolism. For example, it is found in the respiratory enzyme complex [[cytochrome c oxidase]], in the oxygen carrying [[hemocyanin]], and in several [[hydroxylase]]s.<ref>{{cite web |editor-last = Johnson, MD PhD |editor-first = Larry E. |title = Copper |work = Merck Manual Home Health Handbook |publisher = Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc. |date = 2008 |url = http://www.merckmanuals.com/home/disorders_of_nutrition/minerals/copper.html |access-date = 7 April 2013 |archive-date = 7 March 2016 |archive-url = https://web.archive.org/web/20160307024751/http://www.merckmanuals.com/home/disorders_of_nutrition/minerals/copper.html }}</ref> Adult humans contain between 1.4 and 2.1&nbsp;mg of copper per kilogram of body weight.<ref>{{cite web|url=http://www.copper.org/consumers/health/cu_health_uk.html|title=Copper in human health}}</ref>

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==Etymology==
The name of the metal derives from ''aes cyprium'' meaning "metal of [[Cyprus]]" in Latin. In [[Late Latin]] this became {{Lang|la|cuprum}}.  [[Old English]] adopted this as ''{{Lang|ang|Coper}}'' and ''copper'', first used in the 12th century, derives from that word.<ref>{{cite web|url=https://www.merriam-webster.com/dictionary/copper|publisher=Merriam-Webster Dictionary|title=Copper|date=2018|access-date=22 August 2018}}</ref>

==Characteristics==
[[File:Cu-Scheibe.JPG|thumb|left|upright=0.7|A copper disc (99.95% pure) made by [[continuous casting]]; [[industrial etching|etched]] to reveal [[crystallite]]s]]
[[File:Molten copper in bright sunlight.gif|upright=0.7|thumb|left|Copper just above its melting point keeps its pink luster color when enough light outshines the orange [[incandescence]] color.]]
===Physical===
Copper, [[silver]], and [[gold]] are in [[group 11 element|group 11]] of the periodic table; these three metals have one s-orbital electron on top of a filled d-[[electron shell]] and are characterized by high [[ductility]] and electrical and thermal conductivity. The filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through [[metallic bond]]s. Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a [[covalent bond|covalent]] character and are relatively weak. This observation explains the low [[hardness]] and high ductility of [[monocrystalline|single crystals]] of copper.<ref name="b1">{{cite book|first1=George L. |last1=Trigg|first2=Edmund H. |last2=Immergut|title=Encyclopedia of Applied Physics|url=https://books.google.com/books?id=sVQ5RAAACAAJ|access-date=2 May 2011|year=1992|publisher=VCH |isbn=978-3-527-28126-8|pages=267–272|volume=4: Combustion to Diamagnetism}}</ref> At the macroscopic scale, introduction of extended defects to the [[crystal lattice]], such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is usually supplied in a fine-grained [[polycrystalline]] form, which has greater strength than monocrystalline forms.<ref>{{cite book|last1 = Smith |first1=William F.|last2 = Hashemi |first2=Javad|name-list-style = amp |title = Foundations of Materials Science and Engineering|page = 223|publisher = McGraw-Hill Professional|date= 2003|isbn = 978-0-07-292194-6}}</ref>

The softness of copper partly explains its high electrical conductivity ({{val|59.6|e=6|u=[[Siemens (unit)|S]]/m}}) and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature.<ref name="CRC">{{cite book|last = Hammond |first=C. R.|title = The Elements, in Handbook of Chemistry and Physics|edition = 81st|publisher = CRC Press|isbn = 978-0-8493-0485-9|date = 2004|url = https://archive.org/details/crchandbookofche81lide}}</ref> This is because the resistivity to electron transport in metals at room temperature originates primarily from scattering of electrons on thermal vibrations of the lattice, which are relatively weak in a soft metal.<ref name="b1" /> The maximum possible current density of copper in open air is approximately {{val|3.1|e=6|u=A/m<sup>2</sup>}}, above which it begins to heat excessively.<ref>{{cite book|author=Resistance Welding Manufacturing Alliance |title=Resistance Welding Manual|date=2003|publisher=Resistance Welding Manufacturing Alliance|isbn=978-0-9624382-0-2|edition=4th|pages=18–12}}</ref>

Copper is one of a few metallic elements with a natural color other than gray or silver.<ref>{{Cite book|last1 = Chambers|first1 = William|last2 = Chambers|first2 = Robert|title = Chambers's Information for the People|publisher = W. & R. Chambers|date = 1884|volume = L|page = 312|edition = 5th|url = https://books.google.com/books?id=eGIMAAAAYAAJ|isbn = 978-0-665-46912-1}}</ref> Pure copper is orange-red and acquires a reddish [[tarnish]] when exposed to air. This is due to the low [[plasma frequency]] of the metal, which lies in the red part of the visible spectrum, causing it to absorb the higher-frequency green and blue colors.<ref>{{cite web |last1=Ramachandran |first1=Harishankar |title=Why is Copper Red? |url=http://ee.iitm.ac.in/~hsr/ec301/copper.pdf |website=[[IIT Madras]] |access-date=27 December 2022 |date=14 March 2007}}</ref>

As with other metals, if copper is put in contact with another metal in the presence of an [[electrolyte]], [[galvanic corrosion]] will occur.<ref>{{cite web|title=Galvanic Corrosion|url=http://www.corrosion-doctors.org/Forms-galvanic/galvanic-corrosion.htm|work=Corrosion Doctors|access-date=29 April 2011}}</ref>

===Chemical===
Copper does not react with water, but it does slowly react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the [[rust]] that forms on iron in moist air, protects the underlying metal from further corrosion ([[passivation (chemistry)|passivation]]). A green layer of [[verdigris]] (copper carbonate) can often be seen on old copper structures, such as the roofing of many older buildings<ref name="Grieken-2005">{{Cite book|url=https://books.google.com/books?id=3qL3vfUZHMYC|title=Cultural Heritage Conservation and Environmental Impact Assessment by Non-Destructive Testing and Micro-Analysis|last1=Grieken|first1=Rene van|last2=Janssens|first2=Koen|date=2005|publisher=CRC Press|isbn=978-0-203-97078-2|page=197|language=en}}</ref> and the [[Statue of Liberty]].<ref>{{cite web|title=Copper.org: Education: Statue of Liberty: Reclothing the First Lady of Metals – Repair Concerns|url=http://www.copper.org/education/liberty/liberty_reclothed1.html|work=Copper.org|access-date=11 April 2011}}</ref> Copper [[tarnish]]es when exposed to some [[sulfur]] compounds, with which it reacts to form various [[copper sulfide]]s.<ref>{{cite journal|last1=Rickett|first1=B. I.|last2=Payer|first2=J. H.|title=Composition of Copper Tarnish Products Formed in Moist Air with Trace Levels of Pollutant Gas: Hydrogen Sulfide and Sulfur Dioxide/Hydrogen Sulfide|journal=Journal of the Electrochemical Society|date=1995|volume=142|issue=11|pages=3723–3728|doi=10.1149/1.2048404|bibcode=1995JElS..142.3723R}}</ref>

<gallery>

Copper wire comparison.JPG | Unoxidized copper wire (left) and oxidized copper wire (right) 

Royal Observatory Edinburgh East Tower 2010 cropped.jpg |The East Tower of the [[Royal Observatory, Edinburgh]]; the original copper was install in 1894 and the refurbished copper in 1994
</gallery>

===Isotopes===
{{Main|Isotopes of copper}}
There are 29 [[isotope]]s of copper. {{SimpleNuclide|Copper|63}} and {{SimpleNuclide|Copper|65}} are stable, with {{SimpleNuclide|Copper|63}} comprising approximately 69% of naturally occurring copper; both have a [[Spin (physics)|spin]] of {{frac|3|2}}.<ref name="nubase">{{NUBASE 2003}}</ref> The other isotopes are [[radioactivity|radioactive]], with the most stable being {{SimpleNuclide|Copper|67}} with a [[half-life]] of 61.83&nbsp;hours.<ref name="nubase" /> Ten [[nuclear isomer|metastable isomers]] have been characterized; {{SimpleNuclide|Copper|68m}} is the longest-lived with a half-life of 3.8 minutes. Isotopes with a [[mass number]] above 64 decay by [[beta decay|β<sup>−</sup>]], whereas those with a mass number below 64 decay by [[positron emission|β<sup>+</sup>]]. [[Copper-64|{{SimpleNuclide|Copper|64}}]], which has a half-life of 12.7 hours, decays both ways.<ref>{{Cite web |title=Nubase 2020 |url=https://www-nds.iaea.org/relnsd/nubase/nubase_min.html |access-date=2025-10-20 |website=www-nds.iaea.org |language=en}}</ref><ref>{{cite web |url=http://www.nndc.bnl.gov/chart/reCenter.jsp?z=29&n=35 |title=Interactive Chart of Nuclides |work=National Nuclear Data Center |access-date=8 April 2011 |archive-date=25 August 2013 |archive-url=https://web.archive.org/web/20130825141152/http://www.nndc.bnl.gov/chart/reCenter.jsp?z=29&n=35 }}</ref>

{{SimpleNuclide|Copper|62}} and {{SimpleNuclide|Copper|64}} have significant applications. {{SimpleNuclide|Copper|62}} is used in {{SimpleNuclide|Copper|62}}-PTSM as a [[radioactive tracer]] for [[positron emission tomography]].<ref>{{Cite journal | last1 = Okazawad | first1 = Hidehiko | last2 = Yonekura | first2 = Yoshiharu | last3 = Fujibayashi | first3 = Yasuhisa | last4 = Nishizawa | first4 = Sadahiko | last5 = Magata | first5 = Yasuhiro | last6 = Ishizu | first6 = Koichi | last7 = Tanaka | first7 = Fumiko | last8 = Tsuchida |first8 = Tatsuro |last9 = Tamaki |first9 = Nagara |last10 = Konishi | first10 = Junji |date=1994 |title=Clinical Application and Quantitative Evaluation of Generator-Produced Copper-62-PTSM as a Brain Perfusion Tracer for PET |journal=Journal of Nuclear Medicine |volume=35 |issue=12 |pages=1910–1915 |url=http://jnm.snmjournals.org/cgi/reprint/35/12/1910.pdf|pmid=7989968 }}</ref>

===Occurrence===
{{See also|List of copper ores}}
Copper is produced in massive stars<ref>{{cite journal|last1=Romano|first1=Donatella|last2=Matteucci|first2=Fransesca|title=Contrasting copper evolution in ω Centauri and the Milky Way|journal=Monthly Notices of the Royal Astronomical Society: Letters|date=2007|volume=378|issue=1|pages=L59–L63|doi=10.1111/j.1745-3933.2007.00320.x|doi-access=free |bibcode=2007MNRAS.378L..59R|arxiv = astro-ph/0703760|s2cid=14595800}}</ref> and is present in the Earth's crust in a proportion of about 50 [[parts per million]] (ppm).<ref name="emsley">{{cite book|author=Emsley, John|title=Nature's building blocks: an A–Z guide to the elements|url=https://archive.org/details/naturesbuildingb0000emsl|url-access=registration|access-date=2 May 2011|year=2003|publisher=Oxford University Press|isbn=978-0-19-850340-8|pages=[https://archive.org/details/naturesbuildingb0000emsl/page/121 121]–125}}</ref> In nature, copper occurs in a variety of minerals, including [[native copper]], copper sulfides such as [[chalcopyrite]], [[bornite]], [[digenite]], [[covellite]], and [[chalcocite]], copper [[sulfosalt minerals|sulfosalts]] such as [[tetrahedrite|tetrahedite-tennantite]], and [[enargite]], copper carbonates such as [[azurite]] and [[malachite]], and as copper(I) or copper(II) oxides such as [[cuprite]] and [[tenorite]], respectively.<ref name="CRC" /> The largest mass of elemental copper yet discovered weighed 420 tonnes and was found in 1857 on the [[Keweenaw Peninsula]] in Michigan, US.<ref name="emsley" /> Native copper is a [[polycrystal]], with the largest single crystal ever described measuring {{nowrap|4.4 × 3.2 × 3.2 cm}}.<ref>{{cite journal|url = http://www.minsocam.org/ammin/AM66/AM66_885.pdf|journal = American Mineralogist|volume = 66|page=885|date= 1981|title= The largest crystals|last = Rickwood |first=P. C.}}</ref> Copper is the 26th most abundant element in [[Earth's crust]], representing 50&nbsp;ppm compared with 75&nbsp;ppm for [[zinc]], and 14&nbsp;ppm for [[lead]].<ref>{{cite book|author=Emsley, John|title=Nature's building blocks: an A–Z guide to the elements|url=https://archive.org/details/naturesbuildingb0000emsl|url-access=registration|access-date=2 May 2011|year=2003|publisher=Oxford University Press|isbn=978-0-19-850340-8|pages=124, 231, 449, 503}}</ref>

Typical background concentrations of copper do not exceed {{val|1|u=ng/m3}} in the atmosphere; {{val|150|u=mg/kg}} in soil; {{val|30|u=mg/kg}} in vegetation; 2&nbsp;μg/L in freshwater and {{val|0.5|u=μg/L}} in seawater.<ref>{{Cite book|last=Rieuwerts|first=John|title=The Elements of Environmental Pollution|publisher=Earthscan Routledge|year=2015|isbn=978-0-415-85919-6|location=London and New York|page=207|oclc=886492996}}</ref>

==Production==
{{see also|List of countries by copper production}}
[[File:Chuquicamata-002.jpg|thumb|left|[[Chuquicamata]], in Chile, is one of the world's largest [[open-pit mining|open pit]] copper [[mining|mines]].]]

Most copper is mined or [[copper extraction techniques|extracted]] as copper sulfides from large [[open pit mine]]s in [[porphyry copper]] deposits that contain 0.4 to 1.0% copper. Sites include [[Chuquicamata]], in Chile, [[Bingham Canyon Mine]], in Utah, United States, and [[El Chino Mine]], in New Mexico, United States. According to the [[British Geological Survey]], in 2005, Chile was the top producer of copper with at least one-third of the world share followed by the United States, Indonesia and Peru.<ref name="CRC" /> Chile, the world's largest copper producer, supplies the US with 70% of refined copper and alloy imports through 2024. Together with Canada (17%) and Peru (7%), they account for 94% of U.S. copper imports.<ref>{{Cite web |last=Schmitz |first=Sophia |date=2025-04-18 |title=Top Copper Suppliers Urge U.S. to Avoid Tariffs, Warn of Global Repercussions |url=https://metals-wire.net/commodities/top-copper-suppliers-urge-u-s-to-avoid-tariffs-warn-of-global-repercussions/ |access-date=2025-04-25 |website=METALS WIRE |language=en}}</ref><ref>{{Cite web |last=Solomon |first=Daina Beth |date=April 15, 2025 |title=Chile, Canada and Peru push back against Trump's copper tariff probe |url=https://www.reuters.com/markets/commodities/chile-pushes-back-against-trump-copper-tariff-probe-2025-04-15/ |website=Reuters}}</ref> Copper can also be recovered through the [[in-situ leach]] process. Several sites in the state of Arizona are considered prime candidates for this method.<ref>{{cite web |last=Randazzo |first=Ryan |url=https://www.azcentral.com/arizonarepublic/business/articles/2011/06/19/20110619copper-new-method-fight.html |title=A new method to harvest copper |publisher=Azcentral.com |date=19 June 2011 |access-date=25 April 2014 |archive-date=22 June 2011 |archive-url=https://web.archive.org/web/20110622234817/https://www.azcentral.com/arizonarepublic/business/articles/2011/06/19/20110619copper-new-method-fight.html }}</ref> The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.<ref>{{cite journal|title=Metal stocks and sustainability|journal=Proceedings of the National Academy of Sciences |date=2006|volume=103|issue=5|pages=1209–1214|first1=R.B.|last1=Gordon|first2=M.|last2=Bertram|first3=T.E.|last3=Graedel|doi=10.1073/pnas.0509498103|pmc=1360560|pmid=16432205|bibcode = 2006PNAS..103.1209G|doi-access=free }}</ref> An alternative source of copper for [[Deep sea mining|collection]] currently being researched are [[polymetallic nodules]], which are located at the depths of the [[Pacific Ocean]] approximately 3000–6500 meters below sea level. These nodules contain other valuable metals such as [[cobalt]] and [[nickel]].<ref>{{cite book |last1=Beaudoin |first1=Yannick C. |last2=Baker |first2=Elaine |title=Deep Sea Minerals: Manganese Nodules, a physical, biological, environmental and technical review |date=December 2013 |publisher=Secretariat of the Pacific Community |isbn=978-82-7701-119-6 |pages=7–18 |url=https://www.researchgate.net/publication/264763450 |access-date=8 February 2021 |archive-url=https://web.archive.org/web/20241204095547/https://www.researchgate.net/publication/264763450_The_Geology_of_Manganese_Nodules |archive-date=4 December 2024 |url-status=live }}</ref>

===Reserves and prices===
[[File:Copper - world production trend.svg|left|thumb|World production trend]]
Copper has been in use for at least 10,000 years, but more than 95% of all copper ever mined and [[smelting|smelted]] has been extracted since 1900.<ref name="Leonard2006" /> As with many natural resources, the total amount of copper on Earth is vast, with around 10<sup>14</sup> tons in the top kilometer of Earth's crust, which is about 5&nbsp;million years' worth at the current rate of extraction. However, only a tiny fraction of these reserves is economically viable with present-day prices and technologies. Estimates of copper reserves available for mining vary from 25 to 60 years, depending on core assumptions such as the growth rate.<ref>{{cite book|author=Brown, Lester|title=Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble|publisher=New York: W.W. Norton|date=2006|page=[https://archive.org/details/planb20rescuingp00brow_0/page/109 109]|isbn=978-0-393-32831-8|url=https://archive.org/details/planb20rescuingp00brow_0|url-access=registration}}</ref> Recycling is a major source of copper in the modern world.<ref name="Leonard2006">{{cite news |last1=Leonard |first1=Andrew |title=Peak copper? |url=https://www.salon.com/2006/03/02/peak_copper/ |access-date=8 March 2022 |work=Salon |date=3 March 2006 |language=en}}</ref>

[[File:Price of Copper.webp|thumb|325px|right|Price of Copper 1959–2022]]
The price of copper is [[Volatility (finance)|volatile]].<ref>{{cite journal|last=Schmitz|first=Christopher|title=The Rise of Big Business in the World, Copper Industry 1870–1930|journal=Economic History Review|date=1986|volume=39|series=2|issue=3|pages=392–410|jstor=2596347|doi=10.1111/j.1468-0289.1986.tb00411.x}}</ref> After a peak in 2022 the price unexpectedly fell.<ref>{{Cite news |title=Copper is unexpectedly getting cheaper |newspaper=The Economist |url=https://www.economist.com/finance-and-economics/2023/07/06/copper-is-unexpectedly-getting-cheaper |access-date=2023-12-19 |issn=0013-0613}}</ref> And by May 2024, the price on the [[London Metal Exchange]] has reached an all-time high above $11,000 per ton.<ref>{{Cite web |date=2024-05-20 |title=Copper price hits record above $11,000 on bets that shortage looms |url=https://www.mining.com/web/copper-price-hits-record-above-11000-on-bets-that-shortage-looms/ |access-date=2025-04-25 |website=MINING.COM |language=en-US}}</ref>

The global market for copper is one of the most [[Commodification|commodified]] and [[Financialization|financialized]] of the [[commodity market]]s, and has been so for decades.<ref name="Massot-2024">{{Cite book |last=Massot |first=Pascale |title=China's Vulnerability Paradox: How the World's Largest Consumer Transformed Global Commodity Markets |date=2024 |publisher=[[Oxford University Press]] |isbn=978-0-19-777140-2 |location=New York, NY, United States of America |pages=}}</ref>{{Rp|page=213}} The top exporters of raw copper were Zambia ($6.95B) and Chile ($2.16B),  followed by Democratic Republic of the Congo ($1.41B). Raw copper's top importers were China ($6.13B), Switzerland ($3.15B), and India ($2.05B).<ref>{{Cite web |title=The Observatory of Economic Complexity |url=https://oec.world/en/profile/[...bespoke] |access-date=2025-11-04 |website=The Observatory of Economic Complexity |language=en}}</ref>

===Copper demand===
In 2024, global copper production was estimated at roughly 22.8–22.9 million metric tons.<ref>{{Cite web |last=Davis |first=John |date=2025-05-18 |title=Top Copper Mining Companies in 2025: Leaders Shaping the Future of Copper Production |url=https://metals-wire.net/news-of-the-week/top-copper-mining-companies-in-2025-leaders-shaping-the-future-of-copper-production/ |access-date=2025-07-23 |website=METALS WIRE |language=en}}</ref><ref>{{Cite web |last= |date=2024-10-01 |title=Global copper production to grow by 3.2% in 2024, supported by key expansions |url=https://www.mining-technology.com/analyst-comment/global-copper-production-grow-2024-key-expansions/ |access-date=2025-07-23 |website=Mining Technology |language=en-US}}</ref> Copper demand is increasing due to the ongoing [[Electrification|energy transition to electricity]].<ref>{{Cite web |last=Woods |first=Bob |date=2023-09-27 |title=Copper is critical to energy transition. The world is falling way behind on producing enough |url=https://www.cnbc.com/2023/09/27/copper-is-critical-to-climate-the-world-is-way-behind-on-production.html |access-date=2023-12-22 |website=CNBC |language=en}}</ref> China accounts for over half the demand.<ref>{{Cite web |title=China drives copper to 4-month low, raising global economic alarms |url=https://asia.nikkei.com/Business/Markets/Commodities/China-drives-copper-to-4-month-low-raising-global-economic-alarms2 |access-date=2023-12-22 |website=Nikkei Asia |language=en-GB}}</ref>

===Extraction<span class="anchor" id="Methods"></span>===
{{main|Copper extraction}}
[[File:Copper Flash Smelting Process (EN).svg|right|thumb|Scheme of flash smelting process]]
The great majority of copper ores are [[Sulfide|sulfides]]. Common ores are the sulfides [[chalcopyrite]] (CuFeS<sub>2</sub>), [[bornite]] (Cu<sub>5</sub>FeS<sub>4</sub>) and, to a lesser extent, [[covellite]] (CuS) and [[chalcocite]] (Cu<sub>2</sub>S).<ref>{{Greenwood&Earnshaw2nd|pages=1174–1175}}</ref>  These ores occur at the level of <1% Cu. Concentration of the ore is required, which begins with [[comminution]] followed by [[froth flotation]]. The remaining concentrate is smelted, which can be described with two simplified equations:<ref name=Ullmann>{{cite book |doi=10.1002/14356007.a07_471 |chapter=Copper |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2001 |last1=Lossin |first1=Adalbert |isbn=978-3-527-30385-4 }}</ref>

* Cuprous sulfide is oxidized to cuprous oxide:
:2 Cu<sub>2</sub>S + 3 O<sub>2</sub> → 2 Cu<sub>2</sub>O + 2 SO<sub>2</sub>

* Cuprous oxide reacts with cuprous sulfide to convert to ''blister copper'' upon heating:
:2 Cu<sub>2</sub>O + Cu<sub>2</sub>S → 6 Cu + 2 SO<sub>2</sub>

This give crude copper, about 98% Cu by weight, which is purified by electrolysis giving Cu at up to 99.99% purity. During the electrolysis small amounts of  [[silver]] and gold may be precipitated into a sludge that can be reprocessed to recover the precious metals.<ref name=Sicius-2024>{{Cite book |last=Sicius |first=Hermann |url=https://link.springer.com/referencework/10.1007/978-3-662-68921-9 |title=Handbook of the Chemical Elements |date=2024 |publisher=Springer Berlin Heidelberg |isbn=978-3-662-68920-2 |location=Berlin, Heidelberg |language=en |doi=10.1007/978-3-662-68921-9}}</ref>{{rp|798}}

Aside from sulfides, another family of ores are oxides.  Approximately 15% of the world's copper supply derives from these oxides.  The beneficiation process for oxides involves extraction with sulfuric acid solutions followed by electrolysis.  In parallel with the above method for "concentrated" sulfide and oxide ores, copper is recovered from [[mine tailing]]s and heaps.  A variety of methods are used including leaching with sulfuric acid, ammonia, ferric chloride.  Biological methods are also used.<ref name=Ullmann/><ref>{{cite journal|last=Watling |first=H.R. |title=The bioleaching of sulphide minerals with emphasis on copper sulphides – A review |journal=Hydrometallurgy |date=2006 |volume=84 |issue=1 |pages=81–108 |url=http://infolib.hua.edu.vn/Fulltext/ChuyenDe/ChuyenDe07/CDe53/59.pdf |doi=10.1016/j.hydromet.2006.05.001 |bibcode=2006HydMe..84...81W |archive-url=https://web.archive.org/web/20110818131019/http://infolib.hua.edu.vn/Fulltext/ChuyenDe/ChuyenDe07/CDe53/59.pdf |archive-date=18 August 2011}}</ref>

A potential source of copper is polymetallic nodules, which have an estimated concentration 1.3%.<ref>{{cite journal |last1=Su |first1=Kun |last2=Ma |first2=Xiaodong |last3=Parianos |first3=John |last4=Zhao |first4=Baojun |title=Thermodynamic and Experimental Study on Efficient Extraction of Valuable Metals from Polymetallic Nodules |journal=Minerals |date=2020 |volume=10 |issue=4 |page=360 |doi=10.3390/min10040360 |bibcode=2020Mine...10..360S |doi-access=free }}</ref><ref>{{cite web |last1=International Seabed Authority |title=Polymetallic Nodules |url=https://isa.org.jm/files/files/documents/eng7.pdf |publisher=International Seabed Authority |access-date=8 February 2021 |archive-date=23 October 2021 |archive-url=https://web.archive.org/web/20211023145629/https://isa.org.jm/files/files/documents/eng7.pdf }}</ref>

{{Plain image with caption|Ural Mining and Metallurgical Company Copper Map.svg|<big>'''Flowchart of copper refining''' (Ingot casting plant of Uralelektromed)</big>
{{Div col|colwidth=20em}}
# [[Copper extraction techniques#Converting|Blister copper]]
# [[Smelting]]
# [[Reverberatory furnace]]
# [[Slag]] remova
# Copper casting of [[ingot]]s
# Casting wheel
# Ingot removal machine
# Ingots take-off
# [[Minecart|Rail cars]]
# Transportation to the tank house{{Div col end}}|650|center|top|triangle|#ccc}}

===Recycling===
According to the [[International Resource Panel]]'s [[Metal Stocks in Society report]], the global per capita stock of copper in use in society is 35–55&nbsp;kg. Much of this is in more-developed countries (140–300&nbsp;kg per capita) rather than less-developed countries (30–40&nbsp;kg per capita). In 2001, a typical automobile contained 20–30&nbsp;kg of copper.<ref name=Ullmann/> By 2014, the copper and copper alloy content of [[internal combustion engine]] vehicles decreased to 16.8&nbsp;kg, but increased again to 24.5&nbsp;kg by 2023.<ref>{{Cite web |date=May 2024 |title=Chemistry and Automobiles Driving the Future |url=https://www.americanchemistry.com/content/download/16352/file/Chemistry-and-Automobiles-2024.pdf |website=American Chemistry Counsil}}</ref> At the same time, a battery [[electric vehicle]] already contains around 91&nbsp;kg of copper and copper alloys.<ref>{{Cite web |date=2024-05-15 |title=Copper can't be mined fast enough to electrify the US |url=https://news.umich.edu/copper-cant-be-mined-fast-enough-to-electrify-the-us/ |access-date=2025-04-25 |website=University of Michigan News |language=en-US}}</ref>

Like [[aluminium]], copper is recyclable without any loss of quality, both from raw state and from manufactured products.<ref>{{Cite book|url=https://books.google.com/books?id=5_QLBwAAQBAJ&q=copper+recyclable+without+any+loss+of+quality&pg=PA249|title=The Role of Ecological Chemistry in Pollution Research and Sustainable Development|last1=Bahadir|first1=Ali Mufit|last2=Duca|first2=Gheorghe|date=2009|publisher=Springer|isbn=978-90-481-2903-4|language=en}}</ref> An estimated 80% of all copper ever mined is still in use today.<ref>{{cite web|url=http://www.copperinfo.com/environment/recycling.html|title=International Copper Association|access-date=22 July 2009|archive-date=5 March 2012|archive-url=https://web.archive.org/web/20120305203937/http://www.copperinfo.com/environment/recycling.html}}</ref> In volume, copper is the third most recycled metal after iron and aluminium.<ref>{{Cite book|url=https://books.google.com/books?id=BnN3DAAAQBAJ&q=%C2%A0copper+third+most+recycled+metal+after+iron+and+aluminium&pg=PT281|title=The Periodic Table in Minutes|last=Green|first=Dan|date=2016|publisher=Quercus|isbn=978-1-68144-329-4|language=en}}</ref> {{As of|2023}}, recycled copper supplies about one-third<!--35%--> of global demand.<ref>{{Citation|title=The World Copper Factbook 2024|author=((International Copper Study Group))|author-link=International Copper Study Group|url=https://icsg.org/download/2024-09-23-the-world-copper-factbook-2024/?wpdmdl=8185&refresh=67470bf6457501732709366&ind=66f165bba8103&filename=Factbook2024.pdf|access-date=19 December 2024|page=53|archive-date=19 December 2024|archive-url=https://web.archive.org/web/20241219053900/https://icsg.org/download/2024-09-23-the-world-copper-factbook-2024/?wpdmdl=8185&refresh=67470bf6457501732709366&ind=66f165bba8103&filename=Factbook2024.pdf|url-status=live}}</ref>

The process of recycling copper is roughly the same as is used to extract copper but requires fewer steps. High-purity scrap copper is melted in a [[Metallurgical furnace|furnace]] and then [[redox|reduced]] and cast into [[Billet (semi-finished product)|billets]] and [[ingot]]s.<ref>[http://www.copper.org/publications/newsletters/innovations/1998/06/recycle_overview.html "Overview of Recycled Copper" ''Copper.org'']. (25 August 2010). Retrieved on 8 November 2011.</ref> Lower-purity scrap is melted to form ''black copper'' (70–90% pure, containing impurities such as iron, zinc, tin, and nickel), followed by oxidation of impurities in a [[Converting (metallurgy)|converter]] to form blister copper (96–98% pure), which is then [[Copper extraction#Refining|refined]] as before.<ref name=Ullmann7ed-Figure28>{{cite book |doi=10.1002/14356007.a07_471 |chapter=Copper |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2012 |last1=Lossin |first1=Adalbert |isbn=978-3-527-30385-4 |edition=7th |volume=10 |page=202}}</ref>{{rp|p=202}}

=== Historic recycling in the United States ===
By the late twentieth century, secondary copper smelting in the United States was carried out by a small number of dedicated facilities, including [[Chemetco]] (Hartford, Illinois), Carondelet Copper (St. Louis, Missouri), Southwire (Carrollton, Georgia), Federated Metals (Houston, Texas), and AMAX Metals Recovery (Braithwaite, Louisiana). These plants processed copper-bearing scrap and residues from wire, bronzes, brass and industrial waste streams. They had all ceased operation by the early 2000s after the felony conviction of Chemetco under the Clean Water Act meant a tightening of environmental standards, and at the same time, foreign refining capacity expanded.<ref name="USITC2003">{{cite report |url=https://www.usitc.gov/publications/332/pub3639.pdf |title=Industry and Trade Summary: Copper |date=2003 |publisher=United States International Trade Commission |page=13 |access-date=6 October 2025}}</ref><ref name="EPA2001">{{cite web |title=Chemetco Site Overview |url=https://www.epa.gov/superfund/chemetco |access-date=6 October 2025 |publisher=U.S. Environmental Protection Agency}}</ref><ref name="AMM1999">{{cite news |date=15 June 1999 |title=U.S. Secondary Smelters Face Rising Costs, Tougher Rules |work=American Metal Market |publisher=Fastmarkets |page=4}}</ref>

===Environmental impacts===
[[File:AngleseyCopperStream.jpg|right|upright=.5|thumb|[[Acid mine drainage]] from the disused [[Parys Mountain]] copper mines]]
Copper mining creates direct environmental impacts from [[Tailings|tailing]], overburden rocks, and abandoned mines. Tailing includes liquid waste typically sulfide rich, generating [[acid mine drainage]]. The acid in turn may leach heavy metals from surrounding soil. Overburden rocks may also leach heavy metals in areas of high rainfall. These heavy metals can accumulate in downstream farming areas and enter the food chain. Some of these metals are known carcinogens.<ref>{{Cite journal |last=Punia |first=Anita |date=January 2021 |title=Role of temperature, wind, and precipitation in heavy metal contamination at copper mines: a review |url=http://link.springer.com/10.1007/s11356-020-11580-8 |journal=Environmental Science and Pollution Research |language=en |volume=28 |issue=4 |pages=4056–4072 |doi=10.1007/s11356-020-11580-8 |pmid=33188519 |bibcode=2021ESPR...28.4056P |issn=0944-1344|url-access=subscription }}</ref>
Advocacy groups have reported that mining companies exploit local populations by corrupting local officials in parts of the [[Philippines]].<ref>{{cite web |url=https://www.amnesty.fr/responsabilite-des-entreprises/actualites/philippines-attention-terrain-mine |publisher=Amnesty International |title=Philippines: attention, terrain miné |language=fr |trans-title=Philippines: attention, mined land |date=2016-11-09}}</ref>

Indirect impacts include
[[greenhouse gas emissions]] primarily from electricity consumed by the company, especially when sourced from fossil fuels, and from engines required for copper extraction and refinement.
The environmental cost of copper mining was estimated at 3.7&nbsp;kg [[CO2eq|{{CO2}}-eq]] per kg of copper in 2019.<ref>{{cite web |url=https://www.mineralinfo.fr/sites/default/files/documents/2021-10/presentation_comes_20210517_com.pdf |publisher=WeeeCycling |date=2021-05-17 |language=fr |title=Les opportunités du recyclage du cuivre de haute pureté |trans-title=Opportunities for recycling high purity copper}}</ref> [[Codelco]], a major producer in Chile, reported that in 2020 the company emitted 2.8&nbsp;t {{CO2}}-eq per ton (2.8&nbsp;kg {{CO2}}-eq per kg) of fine copper.<ref>{{cite web |url=https://www.codelco.com/sites/site/docs/20221206/20221206220556/annual_memory_2020.pdf |page=109 |publisher=Codelco |title=Annual Memory 2020}}</ref>
{{clear}}

==Alloys==
[[File:1953 Canadian Dime in a box of US Dimes.jpg|thumb|right|Copper alloys are widely used in the production of coinage; seen here are two examples – post-1964 American [[Dime (United States coin)|dime]]s, which are composed of the alloy [[cupronickel]]<ref>{{cite web |title=Dime |url=http://catalog.usmint.gov/coins/proof-sets/ |archive-url=https://web.archive.org/web/20141004031452/http://catalog.usmint.gov/coins/proof-sets/ |archive-date=4 October 2014 |website=[[US Mint]] |access-date=9 July 2019 }}</ref> and a pre-1968 [[Dime (Canadian coin)|Canadian dime]], which is composed of an alloy of 80 percent silver and 20 percent copper.<ref>{{cite web |title=Pride and skill – the 10-cent coin |url=https://www.mint.ca/store/mint/about-the-mint/10-cents-5300008#.XSUUVuhKiUk |website=[[Royal Canadian Mint]] |access-date=9 July 2019}}</ref>]]
{{See also|List of copper alloys}}
Numerous copper [[alloy]]s have been formulated, many with important uses. [[Brass]] is an alloy of copper and [[zinc]]. [[Bronze]] usually refers to copper–[[tin]] alloys, but can refer to any alloy of copper such as [[aluminium bronze]]. Copper-tin bronzes with various additional metals have been used to create [[bell]]s for centuries; the composition of the alloy directly affects the tone and mechanical characteristics of the instrument.<ref>{{Cite journal |last1=Audy |first1=K. |last2=Audy |first2=J. |date=2006-06-01 |title=Analysis of the Bell-Making Process from the Middle Ages to Recent Times |url=https://www.degruyterbrill.com:443/document/doi/10.1515/pm-2006-0071/html |journal=Practical Metallography |language=en |volume=43 |issue=6 |pages=271–292 |doi=10.1515/pm-2006-0071 |issn=2195-8599|url-access=subscription }}</ref> Copper is one of the most important constituents of silver and [[Fineness|karat]] gold solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys.<ref name="goldalloys">{{cite web|url=http://www.utilisegold.com/jewellery_technology/colours/colour_alloys/ |access-date=6 June 2009 |title=Gold Jewellery Alloys |publisher=World Gold Council |archive-url=https://web.archive.org/web/20090414151414/http://www.utilisegold.com/jewellery_technology/colours/colour_alloys |archive-date=14 April 2009}}</ref> Some lead-free [[solder#Solder alloys|solders]] consist of tin alloyed with a small proportion of copper and other metals.<ref>[http://www.balverzinn.com/downloads/Solder_Sn97Cu3.pdf Balver Zinn Solder Sn97Cu3] {{webarchive |url=https://web.archive.org/web/20110707210148/http://www.balverzinn.com/downloads/Solder_Sn97Cu3.pdf |date=7 July 2011 }}. (PDF) . balverzinn.com. Retrieved on 8 November 2011.</ref>

The alloy of copper and [[nickel]], called [[cupronickel]], is used in low-denomination coins, often for the outer cladding. The US five-cent coin (currently called a ''nickel'') consists of 75% copper and 25% nickel in homogeneous composition. Prior to the introduction of cupronickel, which was widely adopted by countries in the latter half of the 20th century,<ref>{{cite web |last1=Deane |first1=D. V. |title=Modern Coinage Systems |url=https://www.britnumsoc.org/publications/Digital%20BNJ/pdfs/1968_BNJ_37_20.pdf |website=British Numismatic Society |access-date=1 July 2019}}</ref> alloys of copper and [[silver]] were also used, with the United States using an alloy of 90% silver and 10% copper until 1965, when circulating silver was removed from all coins with the exception of the half dollar—these were debased to an alloy of 40% silver and 60% copper between 1965 and 1970.<ref>{{cite web |title=What is 90% Silver? |url=https://www.apmex.com/education/bullion/what-is-90-percent-silver-junk-silver |website=[[APMEX|American Precious Metals Exchange]] (APMEX) |access-date=1 July 2019 |archive-date=28 July 2020 |archive-url=https://web.archive.org/web/20200728210159/https://www.apmex.com/education/bullion/what-is-90-percent-silver-junk-silver }}</ref> The alloy of 90% copper and 10% nickel, remarkable for its resistance to corrosion, is used for various objects exposed to seawater, though it is vulnerable to the sulfides sometimes found in polluted harbors and estuaries.<ref>{{Cite book|url=https://books.google.com/books?id=8C7pXhnqje4C|title=Corrosion Tests and Standards|publisher=ASTM International|page=368|language=en|year=2005}}</ref> Alloys of copper with aluminium (about 7%) have a golden color and are used in decorations.<ref name="emsley" /> ''[[Shakudō]]'' is a Japanese decorative alloy of copper containing a low percentage of gold, typically 4–10%, that can be [[patina]]ted to a dark blue or black color.<ref name="Shakudō">{{cite journal|last=Oguchi|first=Hachiro|date=1983|title=Japanese Shakudō: its history, properties and production from gold-containing alloys|journal=Gold Bulletin|volume=16|issue=4|pages=125–132|doi=10.1007/BF03214636|doi-access=free}}<!--|access-date=4 June 2016 --></ref>
{{Clear}}

==Compounds==
[[File:CopperIoxide.jpg|thumb|A sample of [[copper(I) oxide]]]]
{{Main|Copper compounds}}

Copper forms a rich variety of compounds, usually with [[oxidation state]]s +1 and +2, which are often called ''cuprous'' and ''cupric'', respectively.<ref name="Holleman" /> Copper compounds promote or catalyse numerous chemical and biological processes.<ref>{{cite journal |last1=Trammell |first1=Rachel |last2=Rajabimoghadam |first2=Khashayar |last3=Garcia-Bosch |first3=Isaac |title=Copper-Promoted Functionalization of Organic Molecules: from Biologically Relevant Cu/O2 Model Systems to Organometallic Transformations|journal=Chemical Reviews |volume=119 |issue=4 |pages=2954–3031 |date=30 January 2019 |doi=10.1021/acs.chemrev.8b00368|pmid=30698952 |pmc=6571019 }}</ref>

===Binary compounds===
As with other elements, the simplest compounds of copper are binary compounds, i.e. those containing only two elements, the principal examples being oxides, sulfides, and [[halide]]s. Both [[copper(I) oxide|cuprous]] and [[copper(II) oxide|cupric oxides]] are known. Numerous [[copper sulfide]]s are known,<ref name="Wells">{{ cite book | first1 = A. F. | last1 = Wells | title = Structural Inorganic Chemistry | edition = 5th | year = 1984 | publisher = Oxford University Press | isbn = 978-0-19-965763-6 | pages = 1142–1145 }}</ref> being mainly of interest as ores. The stoichiometrically simplest examples [[copper(I) sulfide]] ({{chem2|Cu2S}}) and [[copper monosulfide]] ({{chem2|CuS}}).<ref>{{Greenwood&Earnshaw2nd|pages=1181}}</ref>

Cuprous [[copper(I) chloride|chloride]], [[copper(I) bromide|bromide]], and [[copper(I) iodide|iodide]] are known, but [[copper(I) fluoride]] remains elusive. Cupric [[copper(II) fluoride|fluoride]], [[copper(II) chloride|chloride]], and [[copper(II) bromide|bromide]] are also well characterized. Attempts to prepare copper(II) iodide yield only copper(I) iodide and iodine.<ref name="Holleman">{{cite book |last1=Holleman |first1=A.F. |last2=Wiberg |first2=N. |title=Inorganic Chemistry |date=2001 |publisher=Academic Press |location=San Diego |isbn=978-0-12-352651-9}}</ref>
:2 Cu<sup>2+</sup> + 4 I<sup>−</sup> → 2 CuI + I<sub>2</sub>

===Coordination chemistry===
[[File:Tetramminkupfer(II)-sulfat-Monohydrat Kristalle.png|thumb|left|Copper(II) gives a deep blue coloration in the presence of ammonia ligands. The one used here is [[tetraamminecopper(II) sulfate]].]]
Copper forms [[coordination complex]]es with [[ligand]]s. In aqueous solution, copper(II) exists as {{chem|[Cu|(H|2|O)|6|]|2+}}. This complex exhibits the fastest water exchange rate (speed of water ligands attaching and detaching) for any transition [[metal aquo complex]]. Adding aqueous [[sodium hydroxide]] causes the precipitation of light blue solid [[copper(II) hydroxide]].<ref>{{cite book | title = Inorganic Chemistry | last1 = Housecroft | first1 = C. E. | last2 = Sharpe | first2 = A. G. | year = 2018 | publisher = Prentice Hall | edition = 5th | isbn = 978-1-292-13414-7}}</ref> A simplified equation is: [[File:Cu-pourbaix-diagram.svg|thumbnail|Pourbaix diagram for copper in uncomplexed media (anions other than OH- not considered). Ion concentration 0.001&nbsp;m (mol/kg water). Temperature 25&nbsp;°C.]]
:Cu<sup>2+</sup> + 2 OH<sup>−</sup> → Cu(OH)<sub>2</sub>
[[Ammonia solution|Aqueous ammonia]] results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, forming [[Schweizer's reagent|tetraamminecopper(II)]]:
:{{chem|Cu|(H|2|O)|4|(OH)|2}} + 4 NH<sub>3</sub> → {{chem|[Cu|(H|2|O)|2|(N|H|3|)|4|]|2+}} + 2 H<sub>2</sub>O + 2 OH<sup>−</sup>
Many other [[oxyanion]]s form complexes; these include [[copper(II) acetate]], [[copper(II) nitrate]], and [[copper(II) carbonate]]. [[Copper(II) sulfate]] forms a blue crystalline penta[[hydrate]], the most familiar copper compound in the laboratory. It is used in a [[fungicide]] called the [[Bordeaux mixture]].<ref name="Boux">{{cite book|chapter-url = https://books.google.com/books?id=cItuoO9zSjkC&pg=PA623|page = 623|chapter = Nonsystematic (Contact) Fungicides|title = Ullmann's Agrochemicals|isbn = 978-3-527-31604-5|author1 = Wiley-Vch|date = 2 April 2007| publisher=Wiley }}</ref>
[[File:Tetraamminediaquacopper(II)-3D-balls.png|thumb|right|upright=0.9|[[Ball-and-stick model]] of the complex [Cu(NH<sub>3</sub>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>]<sup>2+</sup>, illustrating the [[octahedral coordination geometry]] common for copper(II)]]

[[Polyol]]s, compounds containing more than one alcohol [[functional group]], generally interact with cupric salts. For example, copper salts are used to test for [[reducing sugars]]. Specifically, using [[Benedict's reagent]] and [[Fehling's solution]] the presence of the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide.<ref>Ralph L. Shriner, Christine K.F. Hermann, Terence C. Morrill, David Y. Curtin, Reynold C. Fuson "The Systematic Identification of Organic Compounds" 8th edition, J. Wiley, Hoboken. {{ISBN|0-471-21503-1}}</ref> Schweizer's reagent and related complexes with [[ethylenediamine]] and other [[amine]]s dissolve [[cellulose]].<ref>{{cite journal | last1 = Saalwächter | first1 = Kay | last2 = Burchard | first2 = Walther | last3 = Klüfers | first3 = Peter | last4 = Kettenbach | first4 = G. | last5 = Mayer | first5 = Peter | last6 = Klemm | first6 = Dieter | last7 = Dugarmaa | first7 = Saran | year = 2000 | title = Cellulose Solutions in Water Containing Metal Complexes | journal = Macromolecules | volume = 33 | issue = 11| pages = 4094–4107 | doi = 10.1021/ma991893m | bibcode = 2000MaMol..33.4094S | citeseerx = 10.1.1.951.5219 }}</ref> [[Amino acid]]s form very stable [[chelate complex]]es with copper(II).<ref name="Berg">{{cite book|editor-last1=Lippard|editor-first1=Stephen J.|editor-last2=Berg|editor-first2=Jeremy M.|title=Principles of bioinorganic chemistry|date=1994|publisher=University Science Books|location=Mill Valley, Calif.|isbn=978-0-935702-72-9}}</ref>

===Organocopper chemistry===
{{Main|Organocopper compound}}
Compounds that contain a carbon-copper bond are known as organocopper compounds. They are very reactive towards oxygen to form copper(I) oxide and have [[Reactions of organocopper reagents|many uses in chemistry]]. They are synthesized by treating copper(I) compounds with [[Grignard reaction|Grignard reagents]], [[terminal alkyne]]s or [[organolithium compound|organolithium reagents]];<ref>"Modern Organocopper Chemistry" Norbert Krause, Ed., Wiley-VCH, Weinheim, 2002. {{ISBN|978-3-527-29773-3}}.</ref> in particular, the last reaction described produces a [[Gilman reagent]]. These can undergo [[substitution reaction|substitution]] with [[alkyl halides]] to form [[coupling reaction|coupling products]]; as such, they are important in the field of [[organic synthesis]]. [[Copper(I) acetylide]] is highly shock-sensitive but is an intermediate in reactions such as the [[Cadiot–Chodkiewicz coupling]]<ref>{{cite journal|last1=Berná|first1=José|last2=Goldup|first2=Stephen|last3=Lee|first3=Ai-Lan|last4=Leigh|first4=David|last5=Symes|first5=Mark|last6=Teobaldi|first6=Gilberto|last7=Zerbetto|first7=Fransesco|title=Cadiot–Chodkiewicz Active Template Synthesis of Rotaxanes and Switchable Molecular Shuttles with Weak Intercomponent Interactions|journal=Angewandte Chemie|date=26 May 2008|volume=120|issue=23|pages=4464–4468|doi=10.1002/ange.200800891|bibcode=2008AngCh.120.4464B}}</ref> and the [[Sonogashira coupling]].<ref>{{cite journal|title = The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry|author = Rafael Chinchilla|author2 = Carmen Nájera|name-list-style = amp|journal = [[Chemical Reviews]]|date = 2007|volume = 107|issue = 3|pages = 874–922|doi = 10.1021/cr050992x|pmid = 17305399 | bibcode=2007ChRv..107..874C }}</ref> [[Nucleophilic conjugate addition|Conjugate addition]] to [[Alpha-beta Unsaturated carbonyl compounds|enone]]s<ref>{{cite journal|date=1986 |title=An Addition of an Ethylcopper Complex to 1-Octyne: (''E'')-5-Ethyl-1,4-Undecadiene |journal=[[Organic Syntheses]] |volume=64 |page=1 |doi=10.15227/orgsyn.064.0001 }}</ref> and [[carbometalation|carbocupration]] of alkynes<ref>{{cite journal |last1=Kharasch |first1=M.S. |last2=Tawney |first2=P.O. |date=1941|title=Factors Determining the Course and Mechanisms of Grignard Reactions. II. The Effect of Metallic Compounds on the Reaction between Isophorone and Methylmagnesium Bromide |journal=Journal of the American Chemical Society |volume=63 |issue=9 |pages=2308–2316 |doi=10.1021/ja01854a005|bibcode=1941JAChS..63.2308K }}</ref> can also be achieved with organocopper compounds. Copper(I) forms a variety of weak complexes with [[alkene]]s and [[carbon monoxide]], especially in the presence of amine ligands.<ref>{{cite journal|last1= Imai |first1= Sadako |last2= Fujisawa |first2= Kiyoshi |last3= Kobayashi |first3= Takako |last4= Shirasawa |first4= Nobuhiko |last5= Fujii |first5= Hiroshi |last6= Yoshimura |first6= Tetsuhiko |last7= Kitajima |first7= Nobumasa |last8= Moro-oka |first8= Yoshihiko |title= <sup>63</sup>Cu NMR Study of Copper(I) Carbonyl Complexes with Various Hydrotris(pyrazolyl)borates: Correlation between 63Cu Chemical Shifts and CO Stretching Vibrations|journal= Inorganic Chemistry |date= 1998| volume =37|pages=3066–3070|doi=10.1021/ic970138r|issue=12}}</ref>

===Copper(III) and copper(IV)===
Copper(III) is most often found in oxides. A simple example is potassium [[cuprate]], KCuO<sub>2</sub>, a blue-black solid.<ref>{{cite book|chapter=Potassium Cuprate (III)|title=Handbook of Preparative Inorganic Chemistry|edition=2nd|editor=G. Brauer|publisher=Academic Press|year=1963|location=NY|volume=1|page=1015}}</ref> The most extensively studied copper(III) compounds are the [[cuprate superconductor]]s. [[Yttrium barium copper oxide]] (YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>) consists of both Cu(II) and Cu(III) centres. Like oxide, [[fluoride]] is a highly [[base (chemistry)|basic]] [[anion]]<ref>{{cite journal|author1=Schwesinger, Reinhard |author2=Link, Reinhard |author3=Wenzl, Peter |author4=Kossek, Sebastian |title=Anhydrous phosphazenium fluorides as sources for extremely reactive fluoride ions in solution|doi=10.1002/chem.200500838|year=2006|journal=Chemistry: A European Journal|volume=12|issue=2|pages=438–45 |pmid=16196062 |bibcode=2006ChEuJ..12..438S }}</ref> and is known to stabilize metal ions in high oxidation states. Both copper(III) and even copper(IV) fluorides are known, [[Potassium hexafluorocuprate(III)|K<sub>3</sub>CuF<sub>6</sub>]] and [[Caesium hexafluorocuprate(IV)|Cs<sub>2</sub>CuF<sub>6</sub>]], respectively.<ref name="Holleman" />

Some copper proteins form [[oxo complex]]es, which, in extensively studied synthetic analog systems, feature copper(III).<ref>{{Cite journal |last1=Mirica |first1=Liviu M. |last2=Ottenwaelder |first2=Xavier |last3=Stack |first3=T. Daniel P. |date=2004-02-01 |title=Structure and Spectroscopy of Copper−Dioxygen Complexes |url=https://pubs.acs.org/doi/10.1021/cr020632z |journal=Chemical Reviews |language=en |volume=104 |issue=2 |pages=1013–1046 |doi=10.1021/cr020632z |pmid=14871148 |bibcode=2004ChRv..104.1013M |issn=0009-2665|url-access=subscription }}</ref><ref>{{cite journal |last1=Lewis |first1=E.A. |last2=Tolman |first2=W.B. |date=2004 |title=Reactivity of Dioxygen-Copper Systems |journal=Chemical Reviews |volume=104 |pages=1047–1076 |doi=10.1021/cr020633r |issue=2 |pmid=14871149}}</ref> With [[tetrapeptide]]s, purple-colored copper(III) complexes are stabilized by the deprotonated [[amide]] ligands.<ref>{{cite journal |last1=McDonald |first1=M.R. |last2=Fredericks |first2=F.C. |last3=Margerum |first3=D.W. |date=1997 |title=Characterization of Copper(III)–Tetrapeptide Complexes with Histidine as the Third Residue |journal=Inorganic Chemistry |volume=36 |pages=3119–3124|doi=10.1021/ic9608713|pmid=11669966 |issue=14}}</ref>

Complexes of copper(III) are also found as intermediates in reactions of organocopper compounds, for example in the [[Kharasch–Sosnovsky reaction]].<ref>{{Greenwood&Earnshaw2nd|page=1187}}</ref><ref>{{ cite journal | first1 = A. | last1 = Hickman | first2 = M. | last2 = Sanford | title = High-valent organometallic copper and palladium in catalysis | journal = Nature | volume = 484 | pages = 177–185 | year = 2012 | issue = 7393 | doi = 10.1038/nature11008 | pmid = 22498623 | pmc = 4384170 | bibcode = 2012Natur.484..177H }}</ref><ref>{{ cite journal | title = Well-defined organometallic Copper(III) complexes: Preparation, characterization and reactivity | first1 = He | last1 = Liu | first2 = Qilong | last2 = Shen | journal = [[Coordination Chemistry Reviews|Coord. Chem. Rev.]] | volume = 442 | year = 2021 | article-number = 213923 | doi = 10.1016/j.ccr.2021.213923}}</ref>

==Biological role==
{{Main|Copper in biology}}

=== Biochemistry ===
[[File:Thylakoid membrane.png|thumb|upright=2|Photosynthesis functions by an elaborate electron transport chain within the [[thylakoid membrane]]. A central link in this chain is [[plastocyanin]], a blue copper protein.]]
The biological role for copper commenced with the appearance of oxygen in Earth's atmosphere.<ref>{{cite journal|pmid=10821735|author=Decker, H.|author2=Terwilliger, N.|name-list-style=amp |title=COPs and Robbers: Putative evolution of copper oxygen-binding proteins|journal= Journal of Experimental Biology |volume=203|pages=1777–1782 |date=2000|issue=Pt 12|doi=10.1242/jeb.203.12.1777|doi-access=free|bibcode=2000JExpB.203.1777D }}</ref>
[[Copper proteins]] have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II).<ref>{{cite book
|first1=Katherine E. |last1=Vest|first2=Hayaa F.|last2=Hashemi|first3=Paul A.|last3=Cobine
|chapter=The Copper Metallome in Eukaryotic Cells |editor1-first=Lucia |editor1-last=Banci |series=Metal Ions in Life Sciences |volume=12
|title=Metallomics and the Cell |date=2013 |pages=451–78|publisher=Springer |isbn=978-94-007-5560-4|doi=10.1007/978-94-007-5561-1_13|pmid=23595680}} electronic-book {{ISBN|978-94-007-5561-1}} {{ISSN|1559-0836}} electronic-{{ISSN|1868-0402}}
</ref> Copper is essential in the aerobic [[Cellular respiration|respiration]] of all [[eukaryotes]]. In [[mitochondria]], it is found in [[cytochrome c oxidase]], which is the last protein in [[oxidative phosphorylation]] which stores energy in [[Adenosine triphosphate|ATP]]. The copper atoms are alternatively reduced and oxidized during the electron transfer to oxygen.<ref>{{Cite book |title=Cell structure & function: an integrated approach |date=1991 |publisher=Saunders College Pub |isbn=978-0-03-047439-2 |editor-last=Loewy |editor-first=Ariel G. |edition=3 |location=Philadelphia |editor-last2=Siekevitz |editor-first2=Philip}}</ref>{{rp|383}} Copper is also found in many [[superoxide dismutase]]s, proteins that catalyze the decomposition of [[superoxide]]s by converting it (by [[disproportionation]]) to oxygen and [[hydrogen peroxide]]:
* Cu<sup>2+</sup>-SOD + O<sub>2</sub><sup>−</sup> → Cu<sup>+</sup>-SOD + O<sub>2</sub> (reduction of copper; oxidation of superoxide)
* Cu<sup>+</sup>-SOD + O<sub>2</sub><sup>−</sup> + 2H<sup>+</sup> → Cu<sup>2+</sup>-SOD + H<sub>2</sub>O<sub>2</sub> (oxidation of copper; reduction of superoxide)

The protein [[hemocyanin]] is the oxygen carrier in most [[mollusk]]s and some [[arthropod]]s such as the [[horseshoe crab]] (''Limulus polyphemus'').<ref name="NOAA">{{cite web|title = Fun facts|work = Horseshoe crab|publisher = University of Delaware|url = http://www.ocean.udel.edu/horseshoecrab/funFacts.html|access-date = 13 July 2008|archive-url = https://web.archive.org/web/20081022053340/http://www.ocean.udel.edu/horseshoecrab/funFacts.html|archive-date = 22 October 2008}}</ref> Because hemocyanin is blue, these organisms have blue blood rather than the red blood of iron-based [[hemoglobin]]. Structurally related to hemocyanin are the [[laccase]]s and [[tyrosinase]]s. Instead of reversibly binding oxygen, these proteins hydroxylate substrates, illustrated by their role in the formation of [[lacquer]]s.<ref name="Lippard">S.J. Lippard, J.M. Berg "Principles of bioinorganic chemistry" University Science Books: Mill Valley, CA; 1994. {{ISBN|0-935702-73-3}}.</ref>

Several copper proteins, such as the "blue copper proteins", do not interact directly with substrates; hence they are not enzymes. These proteins relay electrons by the process called [[electron transfer]].<ref name="Lippard" />
A unique tetranuclear copper center has been found in [[nitrous-oxide reductase]].<ref>
{{cite book
|first1=Lisa K.
|last1= Schneider
|first2=Anja
|last2= Wüst
|first3=Anja
|last3= Pomowski
|first4=Lin
|last4= Zhang
|first5=Oliver
|last5= Einsle
|chapter= No Laughing Matter: The Unmaking of the Greenhouse Gas Dinitrogen Monoxide by Nitrous Oxide Reductase
|editor=Peter M.H. Kroneck
|editor2=Martha E. Sosa Torres
|title=The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment
|series=Metal Ions in Life Sciences
|volume=14
|date=2014
|publisher=Springer
|pages=177–210
|doi=10.1007/978-94-017-9269-1_8
|pmid= 25416395
|isbn= 978-94-017-9268-4
}}
</ref>

Copper levels are closely regulated in both [[prokaryotic]] and [[eukaryotic]] cells to balance critical physiological need but avoid toxicity. 

=== Nutrition ===
[[File:ARS copper rich foods.jpg|thumb|Rich sources of copper include oysters, beef and lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper. Good sources include lobster, nuts and sunflower seeds, green olives, avocados, and wheat bran.]]
Copper is an essential [[trace element]] in plants and animals, but not all microorganisms. The human body contains copper at a level of about 1.4 to 2.1&nbsp;mg per kg of body mass.<ref name="copper.org">{{cite web|url = http://www.copper.org/consumers/health/papers/cu_health_uk/cu_health_uk.html|title = Amount of copper in the normal human body, and other nutritional copper facts|access-date = 3 April 2009|archive-date = 10 April 2009|archive-url = https://web.archive.org/web/20090410055140/http://www.copper.org/consumers/health/papers/cu_health_uk/cu_health_uk.html}}</ref>

====Absorption and regulation====
Copper is absorbed in the gut, then transported to the liver bound to [[serum albumin|albumin]].<ref>{{cite journal|last1=Adelstein|first1=S. J.|last2=Vallee|first2=B. L.|title=Copper metabolism in man|journal=New England Journal of Medicine|date=1961|volume=265|pages=892–897|doi=10.1056/NEJM196111022651806|pmid=13859394|issue=18}}</ref> After processing in the liver, copper is distributed to other tissues in a second phase, which involves the protein [[ceruloplasmin]], carrying the majority of copper in blood. Ceruloplasmin also carries the copper that is excreted in milk, and is particularly well-absorbed as a copper source.<ref>{{cite journal | url = http://www.ajcn.org/content/67/5/965S.abstract | title = Copper transport | pmid = 9587137 | date = 1 May 1998 | author1 = M.C. Linder | journal = The American Journal of Clinical Nutrition | volume = 67 | issue = 5 | pages = 965S–971S | last2 = Wooten | first2 = L. | last3 = Cerveza | first3 = P. | last4 = Cotton | first4 = S. | last5 = Shulze | first5 = R. | last6 = Lomeli | first6 = N.| doi = 10.1093/ajcn/67.5.965S | doi-access = free }}</ref> Copper in the body normally undergoes [[enterohepatic circulation]] (about 5&nbsp;mg a day, vs. about 1&nbsp;mg per day absorbed in the diet and excreted from the body), and the body is able to excrete some excess copper, if needed, via [[bile]], which carries some copper out of the liver that is not then reabsorbed by the intestine.<ref>{{cite book | jstor =20170553 | pmid = 775938 | date =1976 | last1 =Frieden | first1 =E. | last2 =Hsieh | first2 =H.S. | title =Ceruloplasmin: The copper transport protein with essential oxidase activity | journal = <!-- --> | volume =44 | pages =187–236 | doi=10.1002/9780470122891.ch6| series = Advances in Enzymology – and Related Areas of Molecular Biology | isbn = 978-0-470-12289-1}}</ref><ref>{{cite journal | pmid =2301561 | title =Copper transport from ceruloplasmin: Characterization of the cellular uptake mechanism | date =1 January 1990 | author1 =S.S. Percival | journal = American Journal of Physiology. Cell Physiology | volume =258 | issue =1 | pages =C140–C146 | last2 =Harris | first2 =E.D. | doi = 10.1152/ajpcell.1990.258.1.c140 }}</ref>

Copper levels and transport are tightly regulated processes.  At least two copper-specific [[Chaperone (protein)|chaperone]]s have been isolated.<ref>{{cite journal |last1=Burkhead |first1=Jason L. |last2=Gogolin Reynolds |first2=Kathryn A. |last3=Abdel-Ghany |first3=Salah E. |last4=Cohu |first4=Christopher M. |last5=Pilon |first5=Marinus |title=Copper homeostasis |journal=New Phytologist |date=2009 |volume=182 |issue=4 |pages=799–816 |doi=10.1111/j.1469-8137.2009.02846.x |pmid=19402880 |bibcode=2009NewPh.182..799B }}</ref>

====Dietary recommendations====
The [[U.S. Institute of Medicine]] updated the estimated average requirements (EARs) and recommended dietary allowances (RDAs) for copper in 2001. If there is not sufficient information to establish EARs and RDAs, an estimate designated [[Adequate Intake]] (AI) is used instead. The AIs for copper are: 200&nbsp;μg of copper for 0–6-month-old males and females, and 220&nbsp;μg of copper for 7–12-month-old males and females. For both sexes, the RDAs for copper are: 340&nbsp;μg of copper for 1–3 years old, 440&nbsp;μg of copper for 4–8 years old, 700&nbsp;μg of copper for 9–13 years old, 890&nbsp;μg of copper for 14–18 years old and 900&nbsp;μg of copper for ages 19 years and older. For pregnancy, 1,000&nbsp;μg. For lactation, 1,300&nbsp;μg.<ref>[http://www.nationalacademies.org/hmd/~/media/Files/Activity%20Files/Nutrition/DRI-Tables/2_%20RDA%20and%20AI%20Values_Vitamin%20and%20Elements.pdf?la=en Dietary Reference Intakes: RDA and AI for Vitamins and Elements] {{Webarchive|url=https://web.archive.org/web/20181113060244/http://www.nationalacademies.org/hmd/~/media/Files/Activity%20Files/Nutrition/DRI-Tables/2_%20RDA%20and%20AI%20Values_Vitamin%20and%20Elements.pdf?la=en |date=13 November 2018 }} Food and Nutrition Board, Institute of Medicine, National Academies Press, 2011. Retrieved 18 April 2018.</ref> As for safety, the Institute of Medicine also sets [[tolerable upper intake level]]s (ULs) for vitamins and minerals when evidence is sufficient. In the case of copper, the UL is set at 10&nbsp;mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as [[Dietary Reference Intake]]s.<ref>Copper. IN: [https://www.nap.edu/read/10026/chapter/9 Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Copper]. National Academy Press. 2001, PP. 224–257.</ref>

The [[European Food Safety Authority]] (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in the United States. For women and men ages 18 and older, the AIs are set at 1.3 and 1.6&nbsp;mg/day, respectively. AIs for pregnancy and lactation is 1.5&nbsp;mg/day. For children ages 1–17 years, the AIs increase with age from 0.7 to 1.3&nbsp;mg/day. These AIs are higher than the U.S. RDAs.<ref>{{cite web |title=Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies |year=2017 |url=https://www.efsa.europa.eu/sites/default/files/assets/DRV_Summary_tables_jan_17.pdf}}</ref> The European Food Safety Authority reviewed the same safety question and set its UL at 5&nbsp;mg/day, which is half the U.S. value.<ref>{{citation |title=Tolerable Upper Intake Levels For Vitamins And Minerals |publisher=European Food Safety Authority |year=2006 |url=http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf}}</ref>

For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). In 2019, 100% of the Daily Value was revised to 0.9&nbsp;mg to bring it into agreement with the RDA.<ref name="FedReg">{{cite web|url=https://www.gpo.gov/fdsys/pkg/FR-2016-05-27/pdf/2016-11867.pdf |title=Federal Register May 27, 2016 Food Labeling: Revision of the Nutrition and Supplement Facts Labels. FR p. 33982.}}</ref><ref>{{cite web | title=Daily Value Reference of the Dietary Supplement Label Database (DSLD) | website=Dietary Supplement Label Database (DSLD) | url=https://www.dsld.nlm.nih.gov/dsld/dailyvalue.jsp | access-date=16 May 2020 | archive-url=https://web.archive.org/web/20200407073956/https://dsld.nlm.nih.gov/dsld/dailyvalue.jsp | archive-date=7 April 2020 }}</ref>

====Deficiency====
{{main|Copper deficiency}}
Because of its role in facilitating iron uptake, [[copper deficiency]] can produce [[anemia]]-like symptoms, [[neutropenia]], bone abnormalities, hypopigmentation, impaired growth, increased incidence of infections, osteoporosis, hyperthyroidism, and abnormalities in glucose and cholesterol metabolism.<ref>{{Cite book |last1=Scheiber |first1=Ivo |chapter-url=https://link.springer.com/10.1007/978-94-007-7500-8_11 |title=Interrelations between Essential Metal Ions and Human Diseases |last2=Dringen |first2=Ralf |last3=Mercer |first3=Julian F. B. |date=2013 |publisher=Springer Netherlands |isbn=978-94-007-7499-5 |editor-last=Sigel |editor-first=Astrid |volume=13 |location=Dordrecht |pages=359–387 |language=en |chapter=Copper: Effects of Deficiency and Overload |journal=Metal Ions in Life Sciences |doi=10.1007/978-94-007-7500-8_11 |pmid=24470097 |editor-last2=Sigel |editor-first2=Helmut |editor-last3=Sigel |editor-first3=Roland K.O.}}</ref> Conversely, [[Wilson's disease]] is genetic disease that causes an accumulation of copper in body tissues.<ref>{{Cite journal |last1=Ala |first1=Aftab |last2=Walker |first2=Ann P. |last3=Ashkan |first3=Keyoumars |last4=Dooley |first4=James S. |last5=Schilsky |first5=Michael L. |date=2007-02-03 |title=Wilson's disease |url=https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(07)60196-2/abstract |journal=The Lancet |language=English |volume=369 |issue=9559 |pages=397–408 |doi=10.1016/S0140-6736(07)60196-2 |issn=0140-6736 |pmid=17276780|bibcode=2007Lanc..369..397A |url-access=subscription }}</ref>

A minimum dietary value for healthy growth in [[European rabbit]]s has been reported to be at least 3&nbsp;[[Parts per million|ppm]] in the diet.<ref>{{cite journal|author=Hunt, Charles E.|author2=William W. Carlton|name-list-style=amp |pmid=5841854 |date=1965|title=Cardiovascular Lesions Associated with Experimental Copper Deficiency in the Rabbit|journal=Journal of Nutrition |volume=87|pages=385–394|issue=4|doi=10.1093/jn/87.4.385}}</ref> However, higher concentrations of copper (100&nbsp;ppm, 200&nbsp;ppm, or 500&nbsp;ppm) in the diet of rabbits may favorably influence [[Feed conversion ratio|feed conversion efficiency]], growth rates, and carcass dressing percentages.<ref>{{cite journal|url=http://riunet.upv.es/handle/10251/10503?locale-attribute=en|author=Ayyat M.S.|author2=Marai I.F.M.|author3=Alazab A.M. |date=1995|title=Copper-Protein Nutrition of New Zealand White Rabbits under Egyptian Conditions|journal= World Rabbit Science |volume=3|issue=3 |pages=113–118|doi=10.4995/wrs.1995.249|doi-access=free|hdl=10251/10503|hdl-access=free}}</ref>

Severe deficiency can be found by testing for low plasma or serum copper levels, low ceruloplasmin, and low red blood cell superoxide dismutase levels; these are not sensitive to marginal copper status. The "cytochrome c oxidase activity of leucocytes and platelets" has been stated as another factor in deficiency, but the results have not been confirmed by replication.<ref name="Bonhametal2002">{{cite journal|last1=Bonham |first1= Maxine |last2= O'Connor |first2= Jacqueline M. |last3= Hannigan |first3= Bernadette M. |last4= Strain |first4= J.J.|date=2002|title=The immune system as a physiological indicator of marginal copper status? |journal=British Journal of Nutrition|doi=10.1079/BJN2002558|pmid=12010579|volume=87|issue=5|pages=393–403|doi-access=free}}</ref>

===Toxicity===
{{Main|Copper toxicity}}
Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. No retention of copper is expected to occur at the 5&nbsp;mg/day level.<ref>{{Cite journal |last1=EFSA Scientific Committee |last2=More |first2=Simon John |last3=Bampidis |first3=Vasileios |last4=Benford |first4=Diane |last5=Bragard |first5=Claude |last6=Halldorsson |first6=Thorhallur Ingi |last7=Hernández-Jerez |first7=Antonio F |last8=Bennekou |first8=Susanne Hougaard |last9=Koutsoumanis |first9=Kostas |last10=Lambré |first10=Claude |last11=Machera |first11=Kyriaki |last12=Mullins |first12=Ewen |last13=Nielsen |first13=Søren Saxmose |last14=Schlatter |first14=Josef R |last15=Schrenk |first15=Dieter |date=January 2023 |title=Re-evaluation of the existing health-based guidance values for copper and exposure assessment from all sources |journal=EFSA Journal |volume=21 |issue=1 |pages=e07728 |doi=10.2903/j.efsa.2023.7728 |pmc=9843535 |pmid=36694841}}</ref>

Research has shown a link between copper level regulation in the body and several neurological diseases, especially [[Alzheimer's disease]]. The studies suggest the issue is an age-related breakdown of internal regulation mechanism rather than an exposure toxicity.<ref>{{Cite journal |last1=Sensi |first1=Stefano L. |last2=Granzotto |first2=Alberto |last3=Siotto |first3=Mariacristina |last4=Squitti |first4=Rosanna |date=December 2018 |title=Copper and Zinc Dysregulation in Alzheimer's Disease |url=https://linkinghub.elsevier.com/retrieve/pii/S0165614718301792 |journal=Trends in Pharmacological Sciences |language=en |volume=39 |issue=12 |pages=1049–1063 |doi=10.1016/j.tips.2018.10.001|pmid=30352697 |url-access=subscription }}</ref>

Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, resulting in irreversible liver failure.<ref name=Sailer-2024>{{Cite journal |last1=Sailer |first1=Judith |last2=Nagel |first2=Judith |last3=Akdogan |first3=Banu |last4=Jauch |first4=Adrian T. |last5=Engler |first5=Jonas |last6=Knolle |first6=Percy A. |last7=Zischka |first7=Hans |date=2024-09-01 |title=Deadly excess copper |journal=Redox Biology |volume=75 |article-number=103256 |doi=10.1016/j.redox.2024.103256 |issn=2213-2317 |pmc=11269798 |pmid=38959622}}</ref>
Autosomal recessive mutations in copper transport proteins also cause regulation failure, leading to [[Wilson's disease]] with copper accumulation, [[cirrhosis]] of the liver, and psychiatric symptoms.<ref name=Sailer-2024/>

===Bioleaching===
Bacteria have been used to extract copper in industrial scale [[bioleaching]] systems. Microbe solutions percolate through crushed ore converting insoluble copper sulfides to soluble copper sulfates; [[electrowinning]] extracts high purity copper from the resulting solution.<ref name="Geoffrey Michael Gadd 609–643">{{cite journal|title=Metals, minerals and microbes: geomicrobiology and bioremediation|journal=Microbiology|author1-link=Geoffrey Michael Gadd|author=Geoffrey Michael Gadd|volume=156|issue=3|date=March 2010|pages=609–643|doi=10.1099/mic.0.037143-0|pmid=20019082|doi-access=free}}</ref>{{rp|628}}

=== Human exposure ===
In the US, the [[Occupational Safety and Health Administration]] (OSHA) has designated a [[permissible exposure limit]] (PEL) for copper dust and fumes in the workplace as a time-weighted average (TWA) of 1&nbsp;mg/m<sup>3</sup>.<ref>{{PGCH|0151}}</ref> The [[National Institute for Occupational Safety and Health]] (NIOSH) has set a [[recommended exposure limit]] (REL) of 1&nbsp;mg/m<sup>3</sup>, time-weighted average. The [[IDLH]] (immediately dangerous to life and health) value is 100&nbsp;mg/m<sup>3</sup>.<ref>{{PGCH|0150}}</ref> Copper is a constituent of [[tobacco smoke]].<ref>[[OEHHA]] ''[https://oehha.ca.gov/chemicals/copper Copper]''</ref><ref name="TalhoutSchulz2011">{{cite journal|last1=Talhout|first1=Reinskje|last2=Schulz|first2=Thomas|last3=Florek|first3=Ewa|last4=Van Benthem|first4=Jan|last5=Wester|first5=Piet|last6=Opperhuizen|first6=Antoon|title=Hazardous Compounds in Tobacco Smoke|journal=International Journal of Environmental Research and Public Health|volume=8|issue=12|year=2011|pages=613–628|issn=1660-4601|doi=10.3390/ijerph8020613|pmid=21556207|pmc=3084482|doi-access=free}}</ref>

==History==
===Prehistoric===
====Copper Age====
{{Main|Copper Age}} 
{{multiple image
 | align = center
 | image1 = Minoan copper ingot from Zakros, Crete.jpg 
 | alt1 = Ancient copper ingot 
 | caption1 = A corroded copper [[ingot]] from [[Zakros]], [[Crete]], shaped in the form of an animal skin ([[Oxhide ingot|oxhide]]) typical in that era
 | image2 = Chrysocolla Timna 070613.jpg
 | alt2 = Copper ore
 | caption2 = Copper ore ([[chrysocolla]]) in [[Cambrian]] sandstone from [[Chalcolithic]] mines in the [[Timna Valley]], southern [[Israel]]
 | image3=Copper_knife,_spearpoints,_awls,_and_spud,_Late_Archaic_period,_Wisconsin,_3000_BC-1000_BC_-_Wisconsin_Historical_Museum_-_DSC03436.JPG|
 | caption3 = Copper artifacts from the [[Old Copper Complex]] of North America, ~9500–5400 years before present
}}
Copper occurs naturally as [[native copper|native metallic copper]] and was known to some of the oldest civilizations on record. The history of copper use dates to 9000&nbsp;BC in the Middle East;<ref name="discovery">{{cite web|url=http://www.csa.com/discoveryguides/copper/overview.php|title=CSA – Discovery Guides, A Brief History of Copper|publisher=Csa.com|access-date=12 September 2008|archive-date=3 February 2015|archive-url=https://web.archive.org/web/20150203154021/http://www.csa.com/discoveryguides/copper/overview.php}}</ref> a copper pendant was found in northern Iraq that dates to 8700&nbsp;BC.<ref>{{cite book|page = 56|title = Jewelrymaking through History: an Encyclopedia|publisher= Greenwood Publishing Group|date = 2007|isbn = 978-0-313-33507-5|author = Rayner W. Hesse}}No primary source is given in that book.</ref> Evidence suggests that gold and [[meteoric iron]] (but not smelted iron) were the only metals used by humans before copper.<ref name="vander">{{cite web|url=http://elements.vanderkrogt.net/element.php?sym=Cu|title=Copper|publisher=Elements.vanderkrogt.net|access-date=12 September 2008}}</ref> The history of copper metallurgy is thought to follow this sequence: first, [[cold forming|cold working]] of native copper, then [[Annealing (metallurgy)|annealing]], [[smelting]], and, finally, [[lost-wax casting]]. In southeastern [[Anatolia]], all four of these techniques appear more or less simultaneously at the beginning of the [[Neolithic]] {{Circa|7500 BC}}.<ref name="Renfrew1990">{{cite book|last=Renfrew|first=Colin|author-link=Colin Renfrew, Baron Renfrew of Kaimsthorn|title=Before civilization: the radiocarbon revolution and prehistoric Europe|url=https://books.google.com/books?id=jJhHPgAACAAJ|access-date=21 December 2011|date=1990|publisher=Penguin|isbn=978-0-14-013642-5}}</ref>

The earliest evidence of [[lost-wax casting]] copper comes from an amulet found in [[Mehrgarh]], Pakistan, and is dated to 4000&nbsp;BC.<ref>{{Cite journal |last1=Thoury |first1=M. |last2=Mille |first2=B. |last3=Séverin-Fabiani |first3=T. |last4=Robbiola |first4=L. |last5=Réfrégiers |first5=M. |last6=Jarrige |first6=J.-F. |last7=Bertrand |first7=L. |date=2016-11-15 |title=High spatial dynamics-photoluminescence imaging reveals the metallurgy of the earliest lost-wax cast object |journal=Nature Communications |volume=7 |article-number=13356 |doi=10.1038/ncomms13356 |issn=2041-1723 |pmc=5116070 |pmid=27843139|bibcode=2016NatCo...713356T }}</ref> [[Investment casting]] was invented in 4500–4000&nbsp;BC in Southeast Asia<ref name="discovery" /> Smelting was probably discovered in China before 2800&nbsp;BC, in Central America around 600&nbsp;AD, and in West Africa about the 9th or 10th century AD.<ref>{{cite news|author = Cowen, R.|url = http://www.geology.ucdavis.edu/~cowen/~GEL115/115CH3.html|title = Essays on Geology, History, and People: Chapter 3: Fire and Metals|access-date = 7 July 2009|archive-date = 10 May 2008|archive-url = https://web.archive.org/web/20080510150436/http://www.geology.ucdavis.edu/~cowen/~GEL115/115CH3.html}}</ref> [[Carbon dating]] has established mining at [[Alderley Edge Mines|Alderley Edge]] in [[Cheshire]], UK, at 2280 to 1890&nbsp;BC.<ref>{{cite book|author=Timberlake, S.|title=The Archaeology of Alderley Edge: Survey, excavation and experiment in an ancient mining landscape|author2=Prag A.J.N.W.|date=2005|publisher=John and Erica Hedges Ltd.|location=Oxford|page=396|doi=10.30861/9781841717159|isbn=978-1-84171-715-9|name-list-style=amp}}</ref>

[[File:ReconstructedOetziAxe.jpg|thumb|upright=.5|Replica of [[Ötzi]]'s copper axe from the [[Chalcolithic]] Era]]
[[Ötzi the Iceman]], a male dated from 3300 to 3200&nbsp;BC, was found with an axe with a copper head 99.7% pure; high levels of [[arsenic]] in his hair suggest an involvement in copper smelting.<ref name="CSA">{{cite web|title=CSA – Discovery Guides, A Brief History of Copper|url=http://www.csa.com/discoveryguides/copper/overview.php|work=CSA Discovery Guides|access-date=29 April 2011|archive-date=3 February 2015|archive-url=https://web.archive.org/web/20150203154021/http://www.csa.com/discoveryguides/copper/overview.php}}</ref> Experience with copper has assisted the development of other metals; in particular, copper smelting likely led to the discovery of [[bloomery|iron smelting]].<ref name="CSA" />

Production in the [[Old Copper Complex]] in Michigan and Wisconsin is dated between 6500 and 3000&nbsp;BC.<ref name="Pompeani-2021">{{Cite journal |last1=Pompeani |first1=David P |last2=Steinman |first2=Byron A |last3=Abbott |first3=Mark B |last4=Pompeani |first4=Katherine M |last5=Reardon |first5=William |last6=DePasqual |first6=Seth |last7=Mueller |first7=Robin H |title=On the Timing of the Old Copper Complex in North America: A Comparison of Radiocarbon Dates from Different Archaeological Contexts |date=April 2021 |url=https://www.cambridge.org/core/product/identifier/S0033822221000072/type/journal_article |journal=Radiocarbon |language=en |volume=63 |issue=2 |pages=513–531 |doi=10.1017/RDC.2021.7 |bibcode=2021Radcb..63..513P |s2cid=233029733 |issn=0033-8222|url-access=subscription }}</ref><ref name="occ">Pleger, Thomas C. "A Brief Introduction to the Old Copper Complex of the Western Great Lakes: 4000–1000 BC", ''[https://books.google.com/books?id=6NUQNQAACAAJ Proceedings of the Twenty-Seventh Annual Meeting of the Forest History Association of Wisconsin]'', Oconto, Wisconsin, 5 October 2002, pp. 10–18.</ref><ref>Emerson, Thomas E. and McElrath, Dale L. ''[https://books.google.com/books?id=awsA08oYoskC&pg=PA709 Archaic Societies: Diversity and Complexity Across the Midcontinent]'', SUNY Press, 2009 {{ISBN|1-4384-2701-8}}.</ref> A copper spearpoint found in Wisconsin has been dated to 6500&nbsp;BC.<ref name="Pompeani-2021" /> Copper usage by the indigenous peoples of the Old Copper Complex from the [[Great Lakes region]] of North America has been radiometrically dated to as far back as 7500&nbsp;BC.<ref name="Pompeani-2021" /><ref name="Bebber-2022">{{Cite journal |last1=Bebber |first1=Michelle R. |last2=Buchanan |first2=Briggs |last3=Holland-Lulewicz |first3=Jacob |date=2022-04-26 |title=Refining the chronology of North America's copper using traditions: A macroscalar approach via Bayesian modeling |journal=PLOS ONE |language=en |volume=17 |issue=4 |article-number=e0266908 |doi=10.1371/journal.pone.0266908 |issn=1932-6203 |pmc=9041870 |pmid=35472064 |bibcode=2022PLoSO..1766908B |doi-access=free }}</ref><ref>{{Cite journal |last=Malakoff |first=David |date=2021-03-19 |title=Ancient Native Americans were among the world's first coppersmiths |journal=Science |doi=10.1126/science.abi6135 |s2cid=233663403 |issn=0036-8075}}</ref> Indigenous peoples of North America around the [[Great Lakes]] may have also been mining copper during this time, making it one of the oldest known examples of [[copper extraction]] in the world.<ref name="Pompeani-2013">{{Cite journal |last1=Pompeani |first1=David P. |last2=Abbott |first2=Mark B. |last3=Steinman |first3=Byron A. |last4=Bain |first4=Daniel J. |date=2013-05-14 |title=Lake Sediments Record Prehistoric Lead Pollution Related to Early Copper Production in North America |journal=Environmental Science & Technology |volume=47 |issue=11 |pages=5545–5552 |doi=10.1021/es304499c |pmid=23621800 |bibcode=2013EnST...47.5545P |issn=0013-936X}}</ref> There is evidence from prehistoric lead pollution from lakes in Michigan that people in the region began mining copper {{Circa|6000 BC}}.<ref name="Pompeani-2013" /><ref name="Pompeani-2021" /> Evidence suggests that utilitarian copper objects fell increasingly out of use in the Old Copper Complex of North America during the Bronze Age and a shift towards an increased production of ornamental copper objects occurred.<ref>{{Cite journal |last1=Bebber |first1=Michelle R. |last2=Eren |first2=Metin I. |date=2018-10-01 |title=Toward a functional understanding of the North American Old Copper Culture "technomic devolution" |journal=Journal of Archaeological Science |language=en |volume=98 |pages=34–44 |doi=10.1016/j.jas.2018.08.001 |bibcode=2018JArSc..98...34B |s2cid=134060339 |issn=0305-4403|doi-access=free }}</ref>

====Bronze Age====
{{Main|Bronze Age}}
[[File:Egyptian - Blue Faience Saucer and Stand - Walters 481608 - Top.jpg|thumb|Copper was used in blue pigments like this "[[Egyptian blue]]" [[Egyptian faience|faience]] saucer and stand from the Bronze Age, [[New Kingdom of Egypt]] (1400–1325&nbsp;BC).]]
Natural bronze, a type of copper made from ores rich in silicon, arsenic, and (rarely) tin, came into general use in the Balkans around 5500&nbsp;BC.<ref>{{Cite book|title=Chinese Studies in the History and Philosophy of Science and Technology|last=Dainian|first=Fan|page=228}}</ref> Alloying copper with tin to make bronze was first practiced about 4000 years after the discovery of copper smelting, and about 2000 years after "natural bronze" had come into general use.<ref>{{Cite book|title=Epigenetics: The Death of the Genetic Theory of Disease Transmission|last=Wallach|first=Joel}}</ref> Bronze artifacts from the [[Vinča culture]] date to 4500&nbsp;BC.<ref name="antiquity1312">{{cite web | url = http://antiquity.ac.uk/ant/087/ant0871030.htm | title = Tainted ores and the rise of tin bronzes in Eurasia, c. 6500 years ago | first1 = Miljana | last1 = Radivojević | first2 = Thilo | last2 = Rehren | publisher = Antiquity Publications Ltd | date = December 2013 | access-date = 5 February 2014 | archive-date = 5 February 2014 | archive-url = https://archive.today/20140205001504/http://antiquity.ac.uk/ant/087/ant0871030.htm }}</ref> [[Sumer]]ian and [[Ancient Egypt|Egyptian]] artifacts of copper and bronze alloys date to 3000&nbsp;BC.<ref name="hist">{{cite book|pages = 13, 48–66|title = Encyclopaedia of the History of Technology|author = McNeil, Ian |publisher = Routledge|date = 2002|location = London; New York|isbn = 978-0-203-19211-5}}</ref> [[Egyptian blue]], or cuprorivaite (calcium copper silicate), is a synthetic pigment that contains copper and started being used in [[ancient Egypt]] around 3250&nbsp;BC.<ref>{{Cite book |last1=Eastaugh |first1=Nicholas |last2=Walsh |first2=Valentine |last3=Chaplin |first3=Tracey |last4=Siddall |first4=Ruth |date=2013-06-17 |title=Pigment Compendium: Optical Microscopy of Historical Pigments |doi=10.4324/9780080454573|isbn=978-1-136-37379-4 }}</ref> The manufacturing process of Egyptian blue was known to the Romans, but by the fourth century AD the pigment fell out of use and the secret to its manufacturing process became lost. The Roman [[Vitruvius]] said in the first century BC that the blue pigment was made from copper minerals or bronze, lime, and a [[Flux (metallurgy)|flux]] like [[natron]], and this basic recipe has been confirmed in modern times.<ref>{{Cite journal |last1=Mazzocchin |first1=Gian Antonio |last2=Rudello |first2=Danilo |last3=Bragato |first3=Carlo |last4=Agnoli |first4=Francesca |date=January 2004 |title=A short note on Egyptian blue |url=https://linkinghub.elsevier.com/retrieve/pii/S1296207403001109 |journal=Journal of Cultural Heritage |language=en |volume=5 |issue=1 |pages=129–133 |doi=10.1016/j.culher.2003.06.004|url-access=subscription }}</ref>

The [[Bronze Age]] began in Southeastern Europe around 3700–3300&nbsp;BC, in Northwestern Europe about 2500&nbsp;BC. It ended with the beginning of the Iron Age, 2000–1000&nbsp;BC in the Near East, and 600&nbsp;BC in Northern Europe. The transition between the [[Neolithic]] period and the Bronze Age was formerly termed the [[Chalcolithic]] period (copper-stone), when copper tools were used with stone tools. The term has gradually fallen out of favor because in some parts of the world, the Chalcolithic and Neolithic are coterminous at both ends. Brass, an alloy of copper and zinc, is of much more recent origin. It was known to the Greeks, but became a significant supplement to bronze during the Roman Empire.<ref name="hist" />

===Ancient and post-classical===
[[File:Venus symbol (fixed width).svg|thumb|left|upright=0.45|In [[alchemy]] the symbol for copper was also the symbol for the [[Venus (mythology)|goddess]] and planet [[Venus]].]]
[[File:TimnaChalcolithicMine.JPG|thumb|Chalcolithic copper mine in [[Timna Valley]], [[Negev Desert]], Israel]]

In Greece, copper was known by the name {{transliteration|grc|chalkos}} (χαλκός). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as ''aes Cyprium'', {{Lang|la|aes}} being the generic Latin term for copper alloys and ''Cyprium'' from [[Cyprus]], where much copper was mined. The phrase was simplified to ''cuprum'', hence the English ''copper''. [[Aphrodite]] ([[Venus (goddess)|Venus]] in Rome) represented copper in mythology and alchemy because of its lustrous beauty and its ancient use in producing mirrors; Cyprus, the source of copper, was sacred to the goddess. The seven heavenly bodies known to the ancients were associated with the seven metals known in antiquity, and Venus was assigned to copper, both because of the connection to the goddess and because Venus was the brightest heavenly body after the Sun and Moon and so corresponded to the most lustrous and desirable metal after gold and silver.<ref>{{cite journal|title = The Nomenclature of Copper and its Alloys|author = Rickard, T.A. |journal = Journal of the Royal Anthropological Institute|volume = 62|pages = 281–290 |date = 1932|jstor = 2843960|doi = 10.2307/2843960}}</ref>

Copper was the most extensively used metal among natives of North America, with evidence for use going back 7000 years.<ref>{{Cite journal |last=Ehrhardt |first=Kathleen L. |date=September 2009 |title=Copper Working Technologies, Contexts of Use, and Social Complexity in the Eastern Woodlands of Native North America |url=http://link.springer.com/10.1007/s10963-009-9020-8 |journal=Journal of World Prehistory |language=en |volume=22 |issue=3 |pages=213–235 |doi=10.1007/s10963-009-9020-8 |bibcode=2009JWPre..22..213E |issn=0892-7537|url-access=subscription }}</ref> 
Native copper is known to have been extracted from sites on [[Isle Royale]] with primitive stone tools between 800 and 1600&nbsp;AD.<ref>{{cite journal|title = The State of Our Knowledge About Ancient Copper Mining in Michigan|journal = The Michigan Archaeologist|volume = 41|page = 119|author = Martin, Susan R.|date = 1995|url = http://www.ramtops.co.uk/copper.html|issue = 2–3|archive-url = https://web.archive.org/web/20160207073036/http://www.ramtops.co.uk/copper.html|archive-date = 7 February 2016}}</ref> Copper, probably from pure nuggets found in the [[Great Lakes]] area, was worked by repeated hammering and annealing in the North American city of [[Cahokia]] (near modern-day Missouri) around 1000–1300&nbsp;AD.<ref name="Chastain-2011">{{Cite journal |last1=Chastain |first1=Matthew L. |last2=Deymier-Black |first2=Alix C. |last3=Kelly |first3=John E. |last4=Brown |first4=James A. |last5=Dunand |first5=David C. |date=2011-07-01 |title=Metallurgical analysis of copper artifacts from Cahokia |url=https://www.sciencedirect.com/science/article/pii/S0305440311000793 |journal=Journal of Archaeological Science |language=en |volume=38 |issue=7 |pages=1727–1736 |doi=10.1016/j.jas.2011.03.004 |bibcode=2011JArSc..38.1727C |issn=0305-4403|url-access=subscription }}</ref> There are several exquisite copper plates, known as the [[Mississippian copper plates]], that have been found in North America in the area around Cahokia, dating from this time period (1000–1300&nbsp;AD).<ref name="Chastain-2011" />

[[File:Spiro Wulfing and Etowah repousse plates HRoe 2012.jpg|thumb|224x224px|[[Mississippian copper plates]] from North America were produced in this style from around 800 to 1600&nbsp;AD.]]

In South America, a copper mask dated to 1000&nbsp;BC found in the Argentinian Andes is the oldest known copper artifact discovered in the Andes.<ref name="Cortés-2017">{{Cite journal |last1=Cortés |first1=Leticia Inés |last2=Scattolin |first2=María Cristina |date=June 2017 |title=Ancient metalworking in South America: a 3000-year-old copper mask from the Argentinian Andes |journal=Antiquity |language=en |volume=91 |issue=357 |pages=688–700 |doi=10.15184/aqy.2017.28 |s2cid=53068689 |issn=0003-598X|doi-access=free |hdl=11336/39789 |hdl-access=free }}</ref> Peru has been considered the origin for early copper [[metallurgy in pre-Columbian America]], but the copper mask from Argentina suggests that the [[Cajón del Maipo]] of the southern Andes was another important center for early copper workings in South America.<ref name="Cortés-2017" /> Copper metallurgy in Peru dates to around 500&nbsp;BC, with larger scale production beginning around 900&nbsp;AD as part of the rise of the [[Sican culture]] in northern Peru. The production continued through a series of conquests by the [[Chimor]] and [[Inca]] cultures, ending with the Spanish conquest in 1532.<ref>{{Cite journal |last1=Shimada |first1=Izumi |last2=Merkel |first2=John F. |date=1991 |title=Copper-Alloy Metallurgy in Ancient Peru |journal=Scientific American |volume=265 |issue=1 |pages=80–87 |doi=10.1038/scientificamerican0791-80 |jstor=24936982 |bibcode=1991SciAm.265a..80S |issn=0036-8733}}</ref>

In Sub-Saharan Africa, throughout the period from the first mines around 2000 BC in [[Agades]] until the early 1800s, copper was viewed as more precious and prestigious than either gold or silver. Copper was widely traded in Africa and fulfilled a number of religious, political, and social functions. By contrast, local deposit of gold were ignored until contact with Portuguese and Arab traders.<ref>{{Cite book |last=Herbert |first=Eugenia W. |chapter-url=https://books.google.com/books?id=CU4lAnmnUhUC&dq=africa+copper+%22red+gold%22&pg=PR11 |title=Red Gold of Africa: Copper in Precolonial History and Culture |date=1984 |publisher=University of Wisconsin Press |isbn=978-0-299-09604-5 |language=en |chapter=Introduction}}</ref><ref>{{cite encyclopedia |encyclopedia=Oxford Research Encyclopedia of African History |publisher=Oxford University Press |url=https://oxfordre.com/anthropology/display/10.1093/acrefore/9780190854584.001.0001/acrefore-9780190854584-e-485 |title=Central African Copper |year=2023 |last=Nikis |first=Nicolas}}</ref><ref>{{cite encyclopedia |encyclopedia=Oxford Research Encyclopedia of African History |publisher=Oxford University Press |title=Preindustrial Mining and Metallurgy in Africa |year=2020 |last=Bandama |first=Foreman |url=https://oxfordre.com/anthropology/display/10.1093/acrefore/9780190854584.001.0001/acrefore-9780190854584-e-64}}</ref>

The cultural role of copper has been important, particularly in currency. Romans in the 6th through 3rd centuries BC used copper lumps as money. At first, the copper itself was valued, but gradually the shape and look of the copper became more important. [[Julius Caesar]] had his own coins made from brass, while [[Augustus|Octavianus Augustus Caesar]]'s coins were made from Cu-Pb-Sn alloys. With an estimated annual output of around 15,000&nbsp;t, [[Roman metallurgy|Roman copper mining and smelting activities]] reached a scale unsurpassed until the time of the [[Industrial Revolution]]; the [[Roman province|provinces]] most intensely mined were those of [[Hispania]], Cyprus and in Central Europe.<ref>{{cite journal|doi = 10.1126/science.272.5259.246|title = History of Ancient Copper Smelting Pollution During Roman and Medieval Times Recorded in Greenland Ice|pages = 246–249 (247f.)|date = 1996|last1 = Hong|first1 = S.|last2 = Candelone|first2 = J.-P.|issue = 5259|last3 = Patterson|first3 = C.C.|last4 = Boutron|first4 = C.F.|journal = Science|volume = 272|bibcode = 1996Sci...272..246H|s2cid = 176767223}}</ref><ref>{{cite journal|last = de Callataÿ|first = François|date = 2005|title = The Graeco-Roman Economy in the Super Long-Run: Lead, Copper, and Shipwrecks|journal = Journal of Roman Archaeology|volume = 18|pages = 361–372 (366–369)|doi = 10.1017/S104775940000742X|s2cid = 232346123}}</ref>

The gates of the [[Temple of Jerusalem]] used [[Corinthian bronze]], a copper, silver, and gold alloy treated with [[depletion gilding]], which successively removes oxidized copper to create a gold surface coat. The process was most prevalent in [[Alexandria]], where alchemy, inspired by the chemical treatment resulting in gold appearance, is thought to have begun.<ref>{{Cite journal |last=Jacobson |first=David M |date=June 2000 |title=Corinthian bronze and the gold of the alchemists |url=https://link.springer.com/10.1007/BF03216582 |journal=Gold Bulletin |language=en |volume=33 |issue=2 |pages=60–66 |doi=10.1007/BF03216582 |issn=0017-1557}}</ref>

===Modern===
[[File:Copper Pot.jpg|thumb| 18th-century copper [[kettle]] from Norway made from Swedish copper]]
The [[Great Copper Mountain]] was a mine in [[Falun]], Sweden, that operated from the 10th century to 1992. It satisfied two-thirds of Europe's copper consumption in the 17th century and helped fund many of Sweden's wars during that time.<ref>{{cite book|url = https://books.google.com/books?id=4yp-x3TzDnEC&pg=PA60|page = 60|title = Mining in World History|isbn = 978-1-86189-173-0|author1 = Lynch, Martin|year=2004| publisher=Reaktion Books }}</ref> It was referred to as the nation's treasury; Sweden had a [[History of copper currency in Sweden|copper backed currency]].<ref>{{cite web|title=Gold: prices, facts, figures and research: A brief history of money|url=http://www.galmarley.com/FAQs_pages/monetary_history_faqs.htm#Scandinavian%20copper%20money|access-date=22 April 2011}}</ref>

[[File:Viipuri - Viborg.jpg|thumb|[[Chalcography]] of the city of [[Vyborg]] at the turn of the 17th and 18th centuries. The year 1709 carved on the printing plate.]]
Copper is used in roofing,<ref name="Grieken-2005" /> currency, and for photographic technology known as the [[daguerreotype]]. Copper was used in [[Renaissance]] sculpture, and was used to construct the [[Statue of Liberty]]; copper continues to be used in construction of various types. [[Copper electroplating|Copper plating]] and [[copper sheathing]] were widely used to protect the under-water hulls of ships, a technique pioneered by the British Admiralty in the 18th century.<ref>{{cite web|title = Copper and Brass in Ships|url = https://www.copper.org/education/history/60centuries/industrial_age/copperand.html|access-date = 6 September 2016}}</ref> The [[Norddeutsche Affinerie]] in Hamburg was the first modern [[electroplating]] plant, starting its production in 1876.<ref>{{cite journal|doi = 10.1002/adem.200400403|title = Process Optimization in Copper Electrorefining|date = 2004|author = Stelter, M.|journal = Advanced Engineering Materials|volume = 6|issue = 7|pages=558–562|last2 = Bombach|first2 = H.| s2cid=138550311 }}</ref>

During the rise in demand for copper for the Age of Electricity, from the 1880s until the Great Depression of the 1930s, the United States produced one third to half the world's newly mined copper.<ref>{{cite book |last1=Gardner |first1=E. D. |display-authors=et al |title=Copper Mining in North America |date=1938 |publisher=U. S. Bureau of Mines |location=Washington, D. C. |url=https://digital.library.unt.edu/ark:/67531/metadc12571/ |access-date=19 March 2019}}</ref> Major districts included the Keweenaw district of northern Michigan, primarily native copper deposits, which was eclipsed by the vast sulphide deposits of [[Butte, Montana]], in the late 1880s, which itself was eclipsed by porphyry deposits of the Southwest United States, especially at [[Bingham Canyon, Utah]], and [[Morenci, Arizona]]. Introduction of open pit steam shovel mining and innovations in smelting, refining, flotation concentration and other processing steps led to mass production. Early in the twentieth century, [[Arizona]] ranked first, followed by [[Montana]], then [[Utah]] and [[Michigan]].<ref>{{cite book |last1=Hyde |first1=Charles |title=Copper for America, the United States Copper Industry from Colonial Times to the 1990s |date=1998 |publisher=University of Arizona Press |location=Tucson, Arizona |isbn=0-8165-1817-3 |page=passim}}</ref>

[[Flash smelting]] was developed by [[Outokumpu]] in Finland and first applied at [[Harjavalta]] in 1949; the energy-efficient process accounts for 50% of the world's primary copper production.<ref>{{cite web|url = http://www.outokumpu.com/files/Technology/Documents/Newlogobrochures/FlashSmelting.pdf|archive-url = https://web.archive.org/web/20110724043222/http://www.outokumpu.com/files/Technology/Documents/Newlogobrochures/FlashSmelting.pdf|archive-date = 24 July 2011|title = Outokumpu Flash Smelting|publisher = [[Outokumpu]]|page = 2}}</ref>

The [[Intergovernmental Council of Copper Exporting Countries]], formed in 1967 by Chile, Peru, Zaire, and Zambia, operated in the copper market as [[OPEC]] does in oil, though it never achieved the same influence, particularly because the second-largest producer, the United States, was never a member; it was dissolved in 1988.<ref>{{cite journal |author=Karen A. Mingst |date=1976 |title=Cooperation or illusion: an examination of the intergovernmental council of copper exporting countries |journal=International Organization |volume=30 |issue=2 |pages=263–287 |doi=10.1017/S0020818300018270|s2cid=154183817 }}</ref> 
In 2008, China became the world's largest importer of copper.<ref name="Massot-2024" />{{Rp|page=187}}

==Applications==
{{See also|Copper in renewable energy}}
[[File:Kupferfittings 4062.jpg|thumb|Copper fittings for soldered plumbing joints]]
The major applications of copper are electrical wire (60%), roofing and plumbing (20%), and industrial machinery (15%). Copper is used mostly as a pure metal, but when greater hardness is required, it is put into such alloys as [[brass]] and [[bronze]] (5% of total use).<ref name="emsley" /> For more than two centuries, copper paint has been used on boat hulls to control the growth of plants and shellfish.<ref>{{Cite web|url=http://www.boatus.com/magazine/2012/february/copper.asp|title=Is Copper Bottom Paint Sinking?|website=BoatUS Magazine|author=Ryck Lydecker|access-date=2016-06-03|archive-date=1 August 2020|archive-url=https://web.archive.org/web/20200801090801/https://www.boatus.com/magazine/2012/february/copper.asp}}</ref> A small part of the copper supply is used for nutritional supplements and fungicides in agriculture.<ref name="Boux" /><ref name="Applications for Copper">{{cite web|title = Copper|publisher = [[American Elements]]|date = 2008|url = http://www.americanelements.com/cu.html|access-date = 12 July 2008|archive-date = 8 June 2008|archive-url = https://web.archive.org/web/20080608225006/http://www.americanelements.com/cu.html}}</ref> Pure copper's ductility, weakness and high friction between copper chips and cutting tools makes [[machining]] of copper difficult; alloys are preferred for good [[machinability]].<ref>{{Cite book |last1=Zheng |first1=Hongyu |chapter-url=http://link.springer.com/10.1007/978-1-4471-4670-4_2 |title=Handbook of Manufacturing Engineering and Technology |last2=Liu |first2=Kui |date=2015 |publisher=Springer London |isbn=978-1-4471-4669-8 |editor-last=Nee |editor-first=Andrew Y. C. |location=London |pages=899–939 |language=en |chapter=Machinability of Engineering Materials |doi=10.1007/978-1-4471-4670-4_2}}</ref> Copper [[Cookware and bakeware|cookware]] can react with acidic or alkaline foods, leaving a metallic taste, but is useful for whipping egg-whites.<ref>{{Cite news |title=What's the Difference Between Nonreactive and Reactive Pans? |url=https://www.thekitchn.com/whats-the-deal-with-reactive-a-108699 |archive-url=http://web.archive.org/web/20250925042405/https://www.thekitchn.com/whats-the-deal-with-reactive-a-108699 |archive-date=2025-09-25 |access-date=2025-11-07 |work=Kitchn |language=en}}</ref>

===Wire and cable===
{{Main|Copper wire and cable}}

Despite competition from other materials, copper remains the preferred [[electrical conductor]] in nearly all categories of electrical wiring except overhead [[electric power transmission]] where [[aluminium]] is often preferred.<ref>Pops, Horace, 2008, "Processing of wire from antiquity to the future", ''Wire Journal International'', June, pp. 58–66</ref><ref>The Metallurgy of Copper Wire, http://www.litz-wire.com/pdf%20files/Metallurgy_Copper_Wire.pdf {{Webarchive|url=https://web.archive.org/web/20130901142501/http://www.litz-wire.com/pdf%20files/Metallurgy_Copper_Wire.pdf |date=1 September 2013 }}</ref> Copper wire is used in [[power generation]], [[power transmission]], [[electric power distribution]], [[telecommunications]], [[electronics]] circuitry, and countless types of [[electrical equipment]].<ref>Joseph, Günter, 1999, Copper: Its Trade, Manufacture, Use, and Environmental Status, edited by Kundig, Konrad J.A., ASM International, pp. 141–192 and pp. 331–375.</ref> [[Electrical wiring]] is the most important market for the copper industry.<ref>{{cite web|url=http://www.chemistryexplained.com/elements/C-K/Copper.html |title=Copper, Chemical Element – Overview, Discovery and naming, Physical properties, Chemical properties, Occurrence in nature, Isotopes |publisher=Chemistryexplained.com |access-date=16 October 2012}}</ref> This includes structural power wiring, power distribution cable, appliance wire, communications cable, automotive wire and cable, and magnet wire. Roughly half of all copper mined is used for electrical wire and cable conductors.<ref>Joseph, Günter, 1999, Copper: Its Trade, Manufacture, Use, and Environmental Status, edited by Kundig, Konrad J.A., ASM International, p.348</ref> Many electrical devices rely on copper wiring because of its multitude of beneficial properties, such as its high [[electrical conductivity]], [[tensile strength]], [[ductility]], [[creep (deformation)]] resistance, [[corrosion]] resistance, low [[thermal expansion]], high [[thermal conductivity]], ease of [[solder]]ing, and ease of installation.<ref>{{Cite book |title=Electrical engineer's reference book |date=1985 |publisher=Butterworths |isbn=978-1-4831-0263-4 |editor-last=Laughton |editor-first=Michael A. |edition=14 |location=Guildford |editor-last2=Say |editor-first2=Maurice G.}}</ref>{{rp|5.3}}

For a short period from the late 1960s to the late 1970s, copper wiring was replaced by [[aluminium wiring]] in many housing construction projects in America but improper design resulted in fire hazards.<ref>{{Cite web|url=https://www.heimer.com/Inspection-Information/Aluminum-Wiring.html|title=Aluminum Wiring Hazards and Pre-Purchase Inspections.|website=www.heimer.com|access-date=2016-06-03|archive-date=28 May 2016|archive-url=https://web.archive.org/web/20160528104324/http://www.heimer.com/Inspection-Information/Aluminum-Wiring.html}}</ref><ref>{{cite web |title=Repairing aluminum wiring |url=https://www.cpsc.gov/pagefiles/118856/516.pdf |website=U.S. Consumer Product Safety Commission |access-date=23 December 2023 |archive-url=https://web.archive.org/web/20161225171612/https://www.cpsc.gov/pagefiles/118856/516.pdf |archive-date=25 December 2016 |page=1 |quote=A national survey conducted by Franklin Research Institute for CPSC showed that homes built before 1972, and wired with aluminum, are 55 times more likely to have one or more wire connections at outlets reach "Fire Hazard Conditions" than homes wired with copper.}}</ref> The safety issues have since been solved by use of larger sizes of aluminium wire (#8AWG and up), and properly designed aluminium wiring is still being installed in place of copper. For example, the [[Airbus A380]] uses aluminum wire in place of copper wire for electrical power transmission.<ref>{{cite news |url=https://spectrum.ieee.org/manufacturing-mayday |title=Manufacturing Mayday: Production glitches send Airbus into a tailspin |work=[[IEEE Spectrum]] |author=Hellemans, Alexander |date=1 January 2007 |access-date=19 June 2014}}</ref>

===Electronics and related devices===
[[File:Busbars.jpg|thumb|upright=.5|left|Copper electrical [[busbar]]s distributing power to a large building]]
[[Integrated circuit]]s and [[printed circuit board]]s increasingly feature copper in place of aluminium because of its superior electrical conductivity; [[heat sink]]s and [[heat exchanger]]s use copper because of its superior heat dissipation properties. [[Electromagnet]]s, [[vacuum tube]]s, [[cathode-ray tube]]s, and [[magnetron]]s in microwave ovens use copper, as do [[waveguide]]s for microwave radiation.<ref>{{cite web|title=Accelerator: Waveguides (SLAC VVC)|url=http://www2.slac.stanford.edu/vvc/accelerators/waveguide.html|work=SLAC Virtual Visitor Center|access-date=29 April 2011|archive-date=7 February 2006|archive-url=https://web.archive.org/web/20060207181019/http://www2.slac.stanford.edu/vvc/accelerators/waveguide.html}}</ref>

===Electric motors===

Copper's superior [[Copper wire and cable#Electrical conductivity|conductivity]] enhances the efficiency of electrical [[motor (device)|motors]].<ref>IE3 energy-saving motors, Engineer Live, http://www.engineerlive.com/Design-Engineer/Motors_and_Drives/IE3_energy-saving_motors/22687/</ref> This is important because motors and motor-driven systems account for 43–46% of all global electricity consumption and 69% of all electricity used by industry.<ref>Energy‐efficiency policy opportunities for electric motor‐driven systems, International Energy Agency, 2011 Working Paper in the Energy Efficiency Series, by Paul Waide and Conrad U. Brunner, OECD/IEA 2011</ref> Increasing the mass and cross section of copper in a [[Inductor|coil]] increases the efficiency of the motor. [[Induction motor|Copper motor rotors]], a new technology designed for motor applications where energy savings are prime design objectives,<ref>Fuchsloch, J. and E.F. Brush, (2007), "Systematic Design Approach for a New Series of Ultra‐NEMA Premium Copper Rotor Motors", in EEMODS 2007 Conference Proceedings, 10–15 June, Beijing.</ref><ref>Copper motor rotor project; Copper Development Association; {{cite web|url=http://www.copper.org/applications/electrical/motor-rotor |title=Copper.org: Copper Motor Rotor Project |access-date=2012-11-07 |archive-url=https://web.archive.org/web/20120313102458/http://www.copper.org/applications/electrical/motor-rotor |archive-date=13 March 2012 }}</ref> are enabling general-purpose [[induction motor]]s to meet and exceed [[National Electrical Manufacturers Association]] (NEMA) [[premium efficiency]] standards.<ref>NEMA Premium Motors, The Association of Electrical Equipment and Medical Imaging Manufacturers; {{cite web|url=http://www.nema.org/gov/energy/efficiency/premium/ |title=NEMA – NEMA Premium Motors |access-date=2009-10-12 |archive-url=https://web.archive.org/web/20100402081307/http://www.nema.org/gov/energy/efficiency/premium/ |archive-date=2 April 2010}}</ref>

===Architecture===
{{Main|Copper in architecture}}

[[File:Minneapolis City Hall.jpg|thumb|Copper roof on the [[Minneapolis City Hall]], coated with [[patina]]]]
Copper has been used since ancient times as a durable, [[corrosion resistance|corrosion resistant]], and weatherproof architectural material. [[Roofing material|Roofs]], [[flashing (weatherproofing)|flashings]], [[rain gutter]]s, [[downspout]]s, [[dome]]s, [[spire]]s, vaults, and [[door]]s have been made from copper for hundreds or thousands of years. Copper's architectural use has been expanded in modern times to include interior and exterior [[Copper in architecture#Wall cladding|wall cladding]], building [[expansion joint]]s, [[RF shielding|radio frequency shielding]], and [[Antimicrobial copper-alloy touch surfaces|antimicrobial]] and decorative indoor products such as attractive handrails, bathroom fixtures, and counter tops. Some of copper's other important benefits as an architectural material include low [[thermal expansion|thermal movement]], light weight, [[lightning rod|lightning protection]], and recyclability.<ref>Seale, Wayne (2007). The role of copper, brass, and bronze in architecture and design; ''Metal Architecture'', May 2007</ref><ref>Copper roofing in detail; Copper in Architecture; Copper Development Association, U.K., www.cda.org.uk/arch</ref><ref>Architecture, European Copper Institute; http://eurocopper.org/copper/copper-architecture.html {{Webarchive|url=https://web.archive.org/web/20121009005711/http://eurocopper.org/copper/copper-architecture.html |date=9 October 2012 }}</ref><ref>Kronborg completed; Agency for Palaces and Cultural Properties, København, {{cite web|url=http://www.slke.dk/en/slotteoghaver/slotte/kronborg/kronborgshistorie/kronborgfaerdigbygget.aspx?highlight%3Dcopper |title=Kronborg completed – Agency for Palaces and Cultural Properties |access-date=2012-09-12 |archive-url=https://web.archive.org/web/20121024101854/http://www.slke.dk/en/slotteoghaver/slotte/kronborg/kronborgshistorie/kronborgfaerdigbygget.aspx?highlight=copper |archive-date=24 October 2012}}</ref>

The metal's distinctive natural green [[patina]] has long been coveted by architects and designers. The final patina is a particularly durable layer that is highly resistant to atmospheric corrosion, thereby protecting the underlying metal against further weathering.<ref>{{cite web|last = Berg|first = Jan|title = Why did we paint the library's roof?|url = http://www.deforest.lib.wi.us/FAQS.htm|access-date = 20 September 2007 |archive-url = https://web.archive.org/web/20070625065039/http://www.deforest.lib.wi.us/FAQS.htm |archive-date = 25 June 2007}}</ref><ref>Architectural considerations; Copper in Architecture Design Handbook, http://www.copper.org/applications/architecture/arch_dhb/fundamentals/arch_considerations.htm{{Dead link|date=October 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>Peters, Larry E. (2004). Preventing corrosion on copper roofing systems; Professional Roofing, October 2004, http://www.professionalroofing.net</ref> It can be a mixture of carbonate and sulfate compounds in various amounts, depending upon environmental conditions such as sulfur-containing acid rain.<ref>{{cite web|url=http://www.wepanknowledgecenter.org/c/document_library/get_file?folderId%3D517%26name%3DDLFE-2454.pdf |title=Oxidation reaction: Why is the Statue of Liberty blue-green? How does rust work?|first=Chun|last=Wu|publisher=Engage Engineering|website=wepanknowledgecenter.org |access-date=2013-10-25 |archive-url=https://web.archive.org/web/20131025094519/http://www.wepanknowledgecenter.org/c/document_library/get_file?folderId=517&name=DLFE-2454.pdf |archive-date=25 October 2013}}</ref><ref>{{cite journal |doi=10.1016/S0010-938X(98)00093-6 |title=The chemistry of copper patination |date=1998 |last1=Fitzgerald |first1=K.P. |last2=Nairn |first2=J. |last3=Atrens |first3=A. |journal=Corrosion Science |volume=40 |issue=12 |pages=2029–50|bibcode=1998Corro..40.2029F }}</ref><ref>Application Areas: Architecture – Finishes – patina; http://www.copper.org/applications/architecture/finishes.html</ref><ref>Glossary of copper terms, Copper Development Association (UK): {{cite web|url=http://www.copperinfo.co.uk/resources/glossary.shtml |title=Glossary of copper terms |access-date=2012-09-14 |archive-url=https://web.archive.org/web/20120820053020/http://www.copperinfo.co.uk/resources/glossary.shtml |archive-date=20 August 2012 }}</ref> Architectural copper and its alloys can also be [[Copper in architecture#Finishes|'finished']] to take on a particular look, feel, or color. Finishes include mechanical surface treatments, chemical coloring, and coatings.<ref>Finishes – natural weathering; Copper in Architecture Design Handbook, Copper Development Association Inc., {{cite web|url=http://www.copper.org/applications/architecture/arch_dhb/finishes/finishes.html |title=Copper.org: Architecture Design Handbook: Finishes |access-date=2012-09-12 |archive-url=https://web.archive.org/web/20121016080539/http://www.copper.org/applications/architecture/arch_dhb/finishes/finishes.html |archive-date=16 October 2012 }}</ref>

Copper has excellent [[brazing]] and [[soldering]] properties and can be [[welded]]; the best results are obtained with [[gas metal arc welding]].<ref>{{cite book|author = Davis, Joseph R. |title = Copper and Copper Alloys|pages = 3–6, 266|publisher = ASM International|date = 2001|isbn = 978-0-87170-726-0}}</ref>

===Antibiofouling===
{{Main|Copper alloys in aquaculture|Copper sheathing}}

Copper is [[biostatic]], meaning bacteria and many other forms of life will not grow on it. For this reason it has long been used to line parts of ships to protect against [[barnacle]]s and [[mussel]]s. It was originally used pure, but has since been superseded by [[Muntz metal]] and copper-based paint. Similarly, as discussed in [[copper alloys in aquaculture]], copper alloys have become important netting materials in the [[aquaculture]] industry because they are [[antimicrobial]] and prevent [[biofouling]], even in extreme conditions,<ref>Edding, Mario E., Flores, Hector, and Miranda, Claudio, (1995), Experimental Usage of Copper-Nickel Alloy Mesh in Mariculture. Part 1: Feasibility of usage in a temperate zone; Part 2: Demonstration of usage in a cold zone; Final report to the International Copper Association Ltd.</ref> and have strong structural and [[corrosion-resistant]] properties in marine environments.<ref>[http://www.copper.org/applications/cuni/pdf/marine_aquaculture.pdf Corrosion Behaviour of Copper Alloys used in Marine Aquaculture] {{Webarchive|url=https://web.archive.org/web/20130924070759/http://www.copper.org/applications/cuni/pdf/marine_aquaculture.pdf |date=24 September 2013 }}. (PDF) . copper.org. Retrieved on 8 November 2011.</ref>

===Antimicrobial===
{{Main|Antimicrobial properties of copper|Antimicrobial copper-alloy touch surfaces}}

[[Antimicrobial copper-alloy touch surfaces|Copper-alloy touch surfaces]] have natural properties that destroy a wide range of [[microorganisms]] (e.g., ''[[Escherichia coli|E. coli]]'' O157:H7, [[methicillin]]-resistant ''[[Staphylococcus aureus]]'' ([[Methicillin-resistant Staphylococcus aureus|MRSA]]), ''[[Staphylococcus]]'', ''[[Clostridium difficile (bacteria)|Clostridium difficile]]'', [[influenza A virus]], [[Adenoviridae|adenovirus]], [[SARS-CoV-2]], and [[Fungus|fungi]]).<ref name="Copper Touch Surfaces">[http://coppertouchsurfaces.org/antimicrobial/bacteria/index.html Copper Touch Surfaces] {{webarchive|url=https://web.archive.org/web/20120723235812/http://www.coppertouchsurfaces.org/antimicrobial/bacteria/index.html |date=23 July 2012 }}. Copper Touch Surfaces. Retrieved on 8 November 2011.</ref><ref>{{Cite web|date=10 February 2021|title=EPA Registers Copper Surfaces for Residual Use Against Coronavirus|url=https://www.epa.gov/newsreleases/epa-registers-copper-surfaces-residual-use-against-coronavirus|access-date=11 October 2021|website=[[United States Environmental Protection Agency]]}}</ref> Some copper alloys were proven to kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly.<ref name="US EPA-2008">{{Cite web|date=May 2008|title=EPA registers copper-containing alloy products|url=http://www.epa.gov/pesticides/factsheets/copper-alloy-products.htm|archive-url=https://web.archive.org/web/20150929135757/http://www.epa.gov/pesticides/factsheets/copper-alloy-products.htm|archive-date=29 September 2015|website=[[United States Environmental Protection Agency]]}}</ref> The [[United States Environmental Protection Agency]] (EPA) has approved the registrations of these copper alloys as "[[antimicrobial]] materials with public health benefits";<ref name="US EPA-2008" /> that approval allows manufacturers to make legal claims to the public health benefits of products made of registered alloys. In addition, the EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails, [[handrails]], over-bed tables, [[sinks]], [[faucets]], [[door knobs]], [[toilet]] hardware, [[computer keyboards]], [[health club]] equipment, and [[shopping cart]] handles. Copper doorknobs are used by hospitals to minimize the transfer of disease, and [[Legionnaires' disease]] is suppressed by copper tubing in plumbing systems.<ref>{{cite journal|last1=Biurrun|first1=Amaya|last2=Caballero|first2=Luis|last3=Pelaz|first3=Carmen|last4=León|first4=Elena|last5=Gago|first5=Alberto|s2cid=32388649|title=Treatment of a Legionella pneumophila-Colonized Water Distribution System Using Copper-Silver Ionization and Continuous Chlorination|journal=Infection Control and Hospital Epidemiology|date=1999|volume=20|issue=6|pages=426–428|doi=10.1086/501645|jstor=30141645|pmid=10395146|url=http://pdfs.semanticscholar.org/0709/96484f04d87e7c7858448f3d913a94b720c0.pdf|archive-url=https://web.archive.org/web/20190217195047/http://pdfs.semanticscholar.org/0709/96484f04d87e7c7858448f3d913a94b720c0.pdf|archive-date=2019-02-17}}</ref> Antimicrobial copper alloy products are now being installed in healthcare facilities in the UK, Ireland, Japan, Korea, France, Denmark, and Brazil, and in the subway transit system in Santiago, Chile, where copper–zinc alloy handrails were installed in some 30 stations between 2011 and 2014.<ref>[http://www.rail.co/2011/07/22/chilean-subway-protected-with-antimicrobial-copper Chilean subway protected with Antimicrobial Copper – Rail News from] {{webarchive|url=https://web.archive.org/web/20120724105812/http://www.rail.co/2011/07/22/chilean-subway-protected-with-antimicrobial-copper/ |date=24 July 2012 }}. rail.co. Retrieved on 8 November 2011.</ref><ref>[http://construpages.com.ve/nl/noticia_nl.php?id_noticia=3032&language=en Codelco to provide antimicrobial copper for new metro lines (Chile)] {{dead link|date=September 2016|bot=medic}}{{cbignore|bot=medic}}. Construpages.com.ve. Retrieved on 8 November 2011.</ref><ref>[http://www.antimicrobialcopper.com/media/149689/pr811-chilean-subway-installs-antimicrobial-copper.pdf PR 811 Chilean Subway Installs Antimicrobial Copper] {{webarchive|url=https://web.archive.org/web/20111123100624/http://www.antimicrobialcopper.com/media/149689/pr811-chilean-subway-installs-antimicrobial-copper.pdf |date=23 November 2011 }}. (PDF). antimicrobialcopper.com. Retrieved on 8 November 2011.</ref> Copper surfaces in healthcare have been advocated for in the US, as well.<ref>{{Cite web |last=Zaleski |first=Andrew |date=September 24, 2020 |title=As hospitals look to prevent infections, a chorus of researchers make a case for copper surfaces |url=https://www.statnews.com/2020/09/24/as-hospitals-look-to-prevent-infections-a-chorus-of-researchers-make-a-case-for-copper-surfaces/ |access-date=2025-12-24 |website=STAT |language=en-US}}</ref>
Textile fibers can be blended with copper to create antimicrobial protective fabrics.<ref>{{Cite journal |last1=Ali |first1=Azam |last2=Petrů |first2=Michal |last3=Azeem |first3=Musaddaq |last4=Noman |first4=Tayyab |last5=Masin |first5=Ivan |last6=Amor |first6=Nesrine |last7=Militky |first7=Jiri |last8=Tomková |first8=Blanka |date=2023-09-01 |title=A comparative performance of antibacterial effectiveness of copper and silver coated textiles |journal=Journal of Industrial Textiles |language=EN |volume=53 |article-number=15280837221134990 |doi=10.1177/15280837221134990 |issn=1528-0837|doi-access=free }}</ref>

=== Fungicide ===
Copper is widely used as a wood preservative primarily because it is an effective [[fungicide]] against [[Wood-decay_fungus#Soft_rot|soft rot fungi]] while avoiding the significant environmental impact of [[Chromated copper arsenate|chromium and arsenic based preservatives]].<ref>Freeman, M. H., & McIntyre, C. R. (2008). Copper-based wood preservatives. Forest products journal, 58(11), 6-27.</ref> 

===Folk medicine===
Copper is commonly used in jewelry, and according to some folklore, copper bracelets relieve [[arthritis]] symptoms.<ref>{{cite journal |pmid=961545 |date=1976 |last1=Walker |first1=W.R. |last2=Keats |first2=D.M. |title=An investigation of the therapeutic value of the 'copper bracelet'-dermal assimilation of copper in arthritic/rheumatoid conditions |volume=6 |issue=4 |pages=454–459 |journal=Agents and Actions}}</ref> In one trial for osteoarthritis and one trial for rheumatoid arthritis, no differences were found between copper bracelet and control (non-copper) bracelet.<ref>{{cite journal |vauthors=Richmond SJ, Gunadasa S, Bland M, Macpherson H |title=Copper bracelets and magnetic wrist straps for rheumatoid arthritis – analgesic and anti-inflammatory effects: a randomised double-blind placebo controlled crossover trial |journal=PLOS ONE |volume=8 |issue=9 |article-number=e71529 |year=2013 |pmid=24066023 |pmc=3774818 |doi=10.1371/journal.pone.0071529 |bibcode=2013PLoSO...871529R |doi-access=free }}</ref><ref name="RichmondBrown2009">{{cite journal|last1=Richmond|first1=Stewart J.|last2=Brown|first2=Sally R.|last3=Campion|first3=Peter D.|last4=Porter|first4=Amanda J.L.|last5=Moffett|first5=Jennifer A. Klaber|last6=Jackson|first6=David A.|last7=Featherstone|first7=Valerie A.|last8=Taylor|first8=Andrew J.|title=Therapeutic effects of magnetic and copper bracelets in osteoarthritis: A randomised placebo-controlled crossover trial|journal=Complementary Therapies in Medicine|volume=17|issue=5–6|year=2009|pages=249–256|issn=0965-2299|doi=10.1016/j.ctim.2009.07.002|pmid=19942103|url=http://researchrepository.napier.ac.uk/id/eprint/9912}}</ref> No evidence shows that copper can be absorbed through the skin.<ref>{{cite web |url=http://www.uams.edu/update/absolutenm/templates/medical.asp?articleid=3454|title=Find the Truth Behind Medical Myths|publisher=University of Arkansas for Medical Sciences|date=6 January 2014|archive-date=6 January 2014|
archiveurl=https://web.archive.org/web/20140106233901/http://www.uams.edu/update/absolutenm/templates/medical.asp?articleid=3454|quote=While it's never been proven that copper can be absorbed through the skin by wearing a bracelet, research has shown that excessive copper can result in poisoning, causing vomiting and, in severe cases, liver damage.}}</ref>

==See also==
* [[Copper in renewable energy]]
* [[Copper nanoparticle]]
* [[Erosion corrosion of copper water tubes]]
** [[Cold water pitting of copper tube]]
* [[List of countries by copper production]]
* [[Metal theft]]
** [[Operation Tremor]]
* [[Anaconda Copper]]
* [[Antofagasta PLC]]
* [[Codelco]]
* [[El Boleo|El Boleo mine]]
* [[Grasberg mine]]
* [[Copper foil]]

==References==
{{Reflist}}

==Notes==
{| Class = "wikitable" style = "text-align: center"
|+[[Pourbaix diagram]]s for copper
| style="width:25px;"|[[File:Copper in water pourbiax diagram.png|center|200px]]
| style="width:25px;"|[[File:Copper in sulphide media pourbiax diagram.png|center|200px]]
| style="width:25px;"|[[File:Copper in 10M ammonia pourbiax diagram.png|center|200px]]
| style="width:25px;"|[[File:Copper in chloride media more copper pourbiax.png|center|200px]]
|-
|in pure water, or acidic or alkali conditions. Copper in neutral water is more noble than hydrogen.
|in water containing sulfide
|in 10 M ammonia solution
|in a chloride solution
|}

==Further reading==
* {{cite book|title=Handbook of Copper Pharmacology and Toxicology|editor=Massaro, Edward J.|publisher=Humana Press|date=2002|isbn=978-0-89603-943-8}}
* {{cite web|title=''Copper: Technology & Competitiveness (Summary)'' Chapter 6: Copper Production Technology|publisher=Office of Technology Assessment|date=2005|url=http://www.princeton.edu/~ota/disk2/1988/8808/880808.PDF}}
* Current Medicinal Chemistry, Volume 12, Number 10, May 2005, pp.&nbsp;1161–1208(48) Metals, Toxicity and Oxidative Stress
* {{cite book|title=Materials Science and Engineering: an Introduction|url=https://archive.org/details/materialsscience00call_0|url-access=registration|edition=6th|author=William D. Callister|publisher=Wiley, New York|date=2003|isbn=978-0-471-73696-7|at=Table 6.1, p. 137}}
* [http://www.memsnet.org/material/coppercubulk/ Material: Copper (Cu), bulk], MEMS and Nanotechnology Clearinghouse.
* {{cite journal|author=Kim BE|author2= Nevitt T|author3=Thiele DJ|title=Mechanisms for copper acquisition, distribution and regulation|journal=Nat. Chem. Biol.|volume=4|date=2008|pmid=18277979|doi=10.1038/nchembio.72|issue=3|pages=176–85}}

==External links==
{{Wikiquote}}
{{Commons}}
{{Wiktionary|copper}}
{{Wikisource}}
* [https://www.copper.org/education/history/timeline/ Copper Timeline], an interactive history.
* [http://www.periodicvideos.com/videos/029.htm Copper] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [https://www.dcceew.gov.au/environment/protection/npi/substances/fact-sheets/copper-and-compounds Copper and compounds fact sheet] from the [[National Pollutant Inventory]] of Australia
* [https://copperalliance.org/ International Copper Association and the Copper Alliance], a business interest group
* [https://www.copper.org/ Copper.org] – official website of the Copper Development Association, a North American industry association with an extensive site of properties and uses of copper
* [https://www.indexmundi.com/commodities/?commodity=copper&months=300 Price history] of [[LME Copper]], according to the IMF
* [[usgs.gov]] (Mineral Commodity Summaries 2025): [https://pubs.usgs.gov/periodicals/mcs2025/mcs2025.pdf#page=64 Copper]

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{{Copper compounds}}
{{Jewellery}}
{{Authority control}}

{{good article}}

[[Category:Copper| ]]
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Dietary minerals]]
[[Category:Electrical conductors]]
[[Category:Cubic minerals]]
[[Category:Crystals in space group 225]]
[[Category:Native element minerals]]
[[Category:Symbols of Arizona]]
[[Category:Chemical elements with face-centered cubic structure]]
[[Category:Coinage metals and alloys]]