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Copper is a
chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements cannot be broken down into simp ...
with the
symbol A symbol is a mark, sign, or word In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with semantic, objective or pragmatics, practical meaning (linguistics), m ...
Cu (from la, cuprum) and
atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of the electromagnetic radiation emitted (shown) when an electron jumps from one ...
29. It is a soft, malleable, and
ductile Ductility is a mechanical property commonly described as a material's amenability to drawing Drawing is a form of visual art in which an artist uses instruments to mark paper Paper is a thin sheet material produced by mechanically a ...

ductile
metal with very high
thermal Example of a thermal column between the ground and a cumulus A thermal column (or thermal) is a column of rising air File:Atmosphere gas proportions.svg, Composition of Earth's atmosphere by volume, excluding water vapor. Lower pie represe ...

thermal
and
electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current An electric current is a stream of charged particle In p ...
. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a
building material Building material is material used for construction Construction is a general term meaning the and to form , , or ,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford Universit ...

building material
, and as a constituent of various metal
alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts Elec ...
s, such as
sterling silver Sterling silver is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous a ...
used in
jewelry Jewellery or jewelry consists of decorative items worn for personal adornment 150px, The principal adornment of these girls from the Bundu tribe in Sierra Leone is the adornment of bodies and faces with markings produced by the smearing on by ...

jewelry
,
cupronickel Cupronickel or copper-nickel (CuNi) is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fracture ...
used to make marine hardware and
coins A coin is a small, flat, (usually, depending on the country or value) round piece of metal A metal (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hell ...

coins
, and
constantan Constantan is a proprietary name A brand is a name, term, design, symbol or any other feature that identifies one seller's good or service as distinct from those of other sellers. Brands are used in business, marketing, and advertising for re ...
used in
strain gauge A strain gauge (also spelled strain gage) is a device used to measure Deformation (mechanics)#Strain, strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an Electrical insu ...

strain gauge
s and
thermocouples A thermocouple is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage Voltage, electric potential difference, electromotive force e ...

thermocouples
for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable metallic form (
native metal A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native element mineral, native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indiu ...
s). This led to very early human use in several regions, from c. 8000 BC. Thousands of years later, it was the first metal to be
smelted Smelting is a process of applying heat to ore ore – psilomelane Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese Manganese is a chem ...
from sulfide ores, c. 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal,
tin Tin is a with the Sn (from la, ) and  50. Tin is a silvery-colored metal that characteristically has a faint yellow hue. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent ...

tin
, to create
bronze Bronze is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appear ...

bronze
, c. 3500 BC. In the
Roman era In , ancient Rome is civilization from the founding of the Italian city of in the 8th century BC to the collapse of the in the 5th century AD, encompassing the (753 BC–509 BC), (509 BC–27 BC) and (27 BC–476 AD) until the fall of ...
, copper was mined principally on
Cyprus Cyprus ; tr, Kıbrıs (), officially called the Republic of Cyprus,, , lit: Republic of Cyprus is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or politi ...

Cyprus
, the origin of the name of the metal, from ''aes сyprium'' (metal of Cyprus), later corrupted to ''сuprum'' (Latin). ''Coper'' (
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language English is a West Germanic language of the Indo-European language family The Indo-European languages are a language family A language ...
) and ''copper'' were derived from this, the later spelling first used around 1530. Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as
azurite Azurite is a soft, deep-blue produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the at near , . The mineral, a basic with the chemical formula Cu3(CO3)2(OH)2, has been known ...

azurite
,
malachite Malachite is a copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and elec ...

malachite
, and
turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, duct ...

turquoise
, and have been used widely and historically as pigments. Copper used in buildings, usually for roofing, oxidizes to form a green
verdigris Verdigris is the common name for a green Green is the between and on the . It is evoked by light which has a of roughly 495570 . In systems, used in painting and color printing, it is created by a combination of yellow and ; in th ...
(or
patina Patina (or ) is a thin layer that variously forms on the surface of , , and similar ( produced by oxidation or other chemical processes), or certain s, and wooden (sheen produced by age, wear, and polishing), or any similar acquired change ...

patina
). Copper is sometimes used in
decorative art ] The decorative arts are arts or crafts whose object is the design A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process, or the result of that plan or specification ...
, both in its elemental metal form and in compounds as pigments. Copper compounds are used as
bacteriostatic agent A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell The cell (from Latin ''cella'', mea ...
s,
fungicide Fungicides are biocidal chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by hav ...
s, and wood preservatives. Copper is essential to all living organisms as a trace
dietary mineral In the context of nutrition, a mineral is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemica ...
because it is a key constituent of the respiratory enzyme complex
cytochrome c oxidase The enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the su ...
. In
molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda. The members are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil species is es ...

molluscs
and
crustacea Crustaceans (Crustacea ) form a large, diverse arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Eua ...

crustacea
ns, copper is a constituent of the blood pigment
hemocyanin Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). ...
, replaced by the iron-complexed
hemoglobin Hemoglobin or haemoglobin (spelling differences Despite the various English dialects Dialect The term dialect (from Latin , , from the Ancient Greek word , , "discourse", from , , "through" and , , "I speak") is used in two distinct way ...

hemoglobin
in fish and other
vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic ma ...
s. In humans, copper is found mainly in the liver, muscle, and bone. The adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight.


Characteristics


Physical

Copper,
silver Silver is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical ele ...

silver
, and
gold Gold is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same numb ...

gold
are in group 11 of the periodic table; these three metals have one s-orbital electron on top of a filled d-
electron shell In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they un ...
and are characterized by high
ductility Ductility is a mechanical property commonly described as a material's amenability to drawing Drawing is a form of visual art The visual arts are art forms such as painting Painting is the practice of applying paint, pigment, c ...

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 Metallic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of att ...
s. Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a
covalent A covalent bond is a chemical bond A chemical bond is a lasting attraction between atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and take ...
character and are relatively weak. This observation explains the low
hardness Hardness (antonym: softness) is a measure of the resistance to localized induced by either mechanical or . In general, different materials differ in their hardness; for example hard metals such as and are harder than soft metals such as and ...
and high ductility of single crystals of copper. At the macroscopic scale, introduction of extended defects to the
crystal lattice In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of Translation operator (quantum mechanics)#Discrete Translational Symmetry, discrete translation operations described in th ...
, 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 A crystallite is a small or even microscopic crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice ...
form, which has greater strength than monocrystalline forms. The softness of copper partly explains its high electrical conductivity (59.6×106  S/m) and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature. 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. The maximum permissible current density of copper in open air is approximately 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively. Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish
tarnish Tarnish is a thin layer of corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable form such as oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds ...
when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light. As with other metals, if copper is put in contact with another metal,
galvanic corrosion Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential, as a measurable and quant ...
will occur.


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 Rust is an iron oxide Iron oxides are chemical compounds composed of iron and oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), ...

rust
that forms on iron in moist air, protects the underlying metal from further corrosion ( passivation). A green layer of
verdigris Verdigris is the common name for a green Green is the between and on the . It is evoked by light which has a of roughly 495570 . In systems, used in painting and color printing, it is created by a combination of yellow and ; in th ...
(copper carbonate) can often be seen on old copper structures, such as the roofing of many older buildings and the
Statue of Liberty The Statue of Liberty (''Liberty Enlightening the World''; French: ''La Liberté éclairant le monde'') is a List of colossal sculpture in situ, colossal neoclassical sculpture on Liberty Island in New York Harbor in New York City, in the Un ...

Statue of Liberty
. Copper
tarnish Tarnish is a thin layer of corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable form such as oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds ...
es when exposed to some
sulfur Sulfur (in nontechnical British English: sulphur) is a with the  S and  16. It is , and lic. Under , sulfur atoms form cyclic octatomic molecules with a chemical formula . Elemental sulfur is a bright yellow, line solid at . Sul ...

sulfur
compounds, with which it reacts to form various
copper sulfideCopper sulfides describe a family of chemical compounds and minerals with the formula CuxSy. Both mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Eart ...
s.


Isotopes

There are 29
isotope Isotopes are two or more types of atoms that have the same atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of ...
s of copper. 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper; both have a
spin Spin or spinning may refer to: Businesses * or South Pacific Island Network * , an American scooter-sharing system * , a chain of table tennis lounges Computing * , 's tool for formal verification of distributed software systems * , a Mach-like ...
of . The other isotopes are
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration or nuclear disintegration) is the process by which an unstable atomic nucleus The atomic nucleus is the small, dense region consisting of s and s ...

radioactive
, with the most stable being 67Cu with a
half-life Half-life (symbol ''t''1⁄2) is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents an ...
of 61.83 hours. Seven metastable isotopes have been characterized; 68mCu is the longest-lived with a half-life of 3.8 minutes. Isotopes with a
mass number The mass number (symbol ''A'', from the German word ''Atomgewicht'' tomic weight, also called atomic mass number or nucleon number, is the total number of s and s (together known as s) in an . It is approximately equal to the of the expre ...
above 64 decay by , whereas those with a mass number below 64 decay by β+. , which has a half-life of 12.7 hours, decays both ways. 62Cu and 64Cu have significant applications. 62Cu is used in 62Cu-PTSM as a
radioactive tracerA radioactive tracer, radiotracer, or radioactive label, is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tra ...
for
positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in Metabolism, metabolic processes, and in other physiological activities including blo ...
.


Occurrence

Copper is produced in massive stars and is present in the Earth's crust in a proportion of about 50 parts per million (ppm). In nature, copper occurs in a variety of minerals, including
native copper Native copper is an uncombined form of copper Copper is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance c ...

native copper
, copper sulfides such as
chalcopyrite Chalcopyrite ( ) is a copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and e ...

chalcopyrite
,
bornite Bornite, also known as peacock ore, is a with chemical composition 5S4 that crystallizes in the (pseudo-cubic). Appearance Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various shades of blue to purple in places. ...

bornite
,
digenite Digenite is a copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and electrica ...

digenite
,
covellite Covellite (gray) replacing and embaying chalcopyrite (light), polished section from Horn Silver Mine, San Francisco Mining District, alt= Covellite (also known as covelline) is a rare copper sulfide mineral In geology Geology (from the ...

covellite
, and
chalcocite Chalcocite (), copper(I) sulfide (Cu2S), is an important copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high ...

chalcocite
, copper sulfosalts such as , and , copper carbonates such as
azurite Azurite is a soft, deep-blue produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the at near , . The mineral, a basic with the chemical formula Cu3(CO3)2(OH)2, has been known ...

azurite
and
malachite Malachite is a copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and elec ...

malachite
, and as copper(I) or copper(II) oxides such as
cuprite Cuprite is an oxide mineral composed of copper(I) oxide Cu2O, and is a minor ore of copper. Its dark crystals with red internal reflections are in the Cubic (crystal system), isometric system hexoctahedral class, appearing as cubic, octahedral, or ...

cuprite
and
tenorite Tenorite is a copper oxide mineral with the chemical formula CuO. Occurrence Tenorite occurs in the weathered or oxidized zone associated with deeper primary copper sulfide orebodies. Tenorite commonly occurs with chrysocolla and the copper car ...
, respectively. The largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the
Keweenaw Peninsula 250px, Keweenaw Peninsula The Keweenaw Peninsula ( , sometimes locallyIn mathematics, a mathematical object is said to satisfy a property locally, if the property is satisfied on some limited, immediate portions of the object (e.g., on some ''suf ...
in Michigan, US. Native copper is a
polycrystal A crystallite is a small or even microscopic crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice ...
, with the largest single crystal ever described measuring 4.4×3.2×3.2 cm. Copper is the 25th most abundant element in
Earth's crust 350px, Plates in the crust of Earth Earth's crust is a thin shell on the outside of Earth, accounting for less than 1% of Earth's volume. It is the top component of the lithosphere, a division of Earth's layers that includes the Crust (geology), ...
, representing 50 ppm compared with 75 ppm for
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
, and 14 ppm for
lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate h ...

lead
. Typical background concentrations of copper do not exceed 1 ng/m3 in the atmosphere; 150 mg/kg in soil; 30 mg/kg in vegetation; 2 μg/L in freshwater and 0.5 μg/L in seawater.


Production

Most copper is mined or extracted as copper sulfides from large
open pit mine File:Ende Gelände 2017 CHB 23 (cropped).jpg, The giant bucket-wheel excavators in the German Rhineland coal mines are among the world's biggest land vehicles. Open-pit mining, also known as open-cast or open cut mining, is a surface mining techni ...

open pit mine
s in
porphyry copper Bingham Canyon mine in 2005. The gray rocks visible in the pit are almost all in the primary-sulfide ore zone. Porphyry copper deposits are copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and at ...
deposits that contain 0.4 to 1.0% copper. Sites include
Chuquicamata Chuquicamata ( ; referred to as Chuqui for short) is the largest open-pit mining, open pit copper Mining, mine by excavated volume in the world. It is located in the north of Chile, just outside Calama, Chile, Calama at above sea level, northeas ...

Chuquicamata
, in Chile,
Bingham Canyon Mine The Bingham Canyon Mine, more commonly known as Kennecott Copper Mine among locals, is an open-pit mining operation extracting a large porphyry copper deposit southwest of Salt Lake City, Utah, in the Oquirrh Mountains. The mine is the largest ma ...
, in Utah, United States, and El Chino Mine, in New Mexico, United States. According to the
British Geological Survey The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. The BGS hea ...

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. Copper can also be recovered through the
in-situ leach In-situ leaching (ISL), also called in-situ recovery (ISR) or solution mining, is a mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or p ...
process. Several sites in the state of Arizona are considered prime candidates for this method. 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. An alternative source of copper for
collection Collection or Collections may refer to: * Cash collection, the function of an accounts receivable department * Collection agency, agency to collect cash * Collections management (museum) ** Collection (artwork), objects in a particular field fo ...
currently being researched are
polymetallic nodulesPolymetallic nodules, also called manganese nodules, are rock concretion Marlstone aggregate concretion, Sault Ste. Marie, Michigan. A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces ...
, which are located at the depths of the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. ...

Pacific Ocean
approximately 3000–6500 meters below sea level. These nodules contain other valuable metals such as
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

cobalt
and
nickel Nickel is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

nickel
.


Reserves and prices

Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined and
smelted Smelting is a process of applying heat to ore ore – psilomelane Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese Manganese is a chem ...
has been extracted since 1900, and more than half was extracted during the last 24 years. As with many natural resources, the total amount of copper on Earth is vast, with around 1014 tons in the top kilometer of Earth's crust, which is about 5 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. Recycling is a major source of copper in the modern world. Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of
peak copper Peak copper is the point in time at which the maximum global copper Copper is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons i ...
, analogous to
peak oil''For Peak brand motor oil, see Peak (automotive products).'' Hubbert's upper-bound prediction for US crude oil production (1956) in red, and actual lower-48 states production through to 2014 in green Peak oil is the year when the maximum r ...
. The price of copper has historically been unstable, and its price increased from the 60-year low of US$0.60/lb (US$1.32/kg) in June 1999 to $3.75 per pound ($8.27/kg) in May 2006. It dropped to $2.40/lb ($5.29/kg) in February 2007, then rebounded to $3.50/lb ($7.71/kg) in April 2007. In February 2009, weakening global demand and a steep fall in commodity prices since the previous year's highs left copper prices at $1.51/lb ($3.32/kg). Between September 2010 and February 2011, the price of copper rose from £5,000 a metric ton to £6,250 a metric ton.


Methods

The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2), bornite (Cu5FeS4) and, to a lesser extent, covellite (CuS) and chalcocite (Cu2S). Conversely, the average concentration of copper in polymetallic nodules is estimated at 1.3%. The methods of extracting copper as well as other metals found in these nodules include sulphuric leaching,
smelting Smelting is a process of applying heat to ore in order to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, silver, iron-making, iron, copper ...
and an application of the Cuprion process. For minerals found in land ores, they are concentrated from
crushed Crushed may refer to: * Crushed (Roland Lee Gift song), ''Crushed'' (Roland Lee Gift song) a 2009 single by Roland Lee Gift * Crushed (The Suite Life of Zack & Cody episode), ''Crushed'' (''The Suite Life of Zack & Cody'' episode), an episode of th ...

crushed
ores to the level of 10–15% copper by
froth flotation Froth flotation is a process for selectively separating of hydrophobic materials from hydrophilic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry, w ...
or
bioleaching Bioleaching is the extraction of metals from their ores through the use of living organisms. This is much cleaner than the traditional heap leaching using cyanide. Bioleaching is one of several applications within biohydrometallurgy and several meth ...
. Heating this material with
silica Silicon dioxide, also known as silica, is an oxide An oxide () is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any su ...

silica
in
flash smelting lang=en, upright=1.3, Development of flash smelting in the copper industry, related to the number of smelters using this technology. Flash smelting ( fi, Liekkisulatus, literally "flame-smelting") is a smelting process for sulfur-containing ores ...
removes much of the iron as
slag Slag is a by-product of smelting Smelting is a process of applying heat to ore in order to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, ...

slag
. The process exploits the greater ease of converting iron sulfides into oxides, which in turn react with the silica to form the
silicate In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atoms, ...
slag that floats on top of the heated mass. The resulting ''copper matte,'' consisting of Cu2S, is
roasted Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven upA double oven A ceramic oven An oven is a tool A tool is an object t ...
to convert all sulfides into oxides: :2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2 The cuprous oxide is converted to ''blister'' copper upon heating: :2 Cu2O → 4 Cu + O2 The Sudbury matte process converted only half the sulfide to oxide and then used this oxide to remove the rest of the sulfur as oxide. It was then electrolytically refined and the anode mud exploited for the
platinum Platinum is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical el ...

platinum
and gold it contained. This step exploits the relatively easy reduction of copper oxides to copper metal.
Natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting of methane and commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxid ...

Natural gas
is blown across the blister to remove most of the remaining oxygen and
electrorefining Electrowinning, also called electroextraction, is the electrodeposition of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, s ...
is performed on the resulting material to produce pure copper: :Cu2+ + 2 e → Cu


Recycling

Like
aluminium Aluminium (aluminum in and ) is a with the  Al and  13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity towards , and of on the surface when exposed to air ...

aluminium
, copper is recyclable without any loss of quality, both from raw state and from manufactured products. In volume, copper is the third most recycled metal after iron and aluminium. An estimated 80% of all copper ever mined is still in use today. According to the
International Resource Panel The International Resource Panel is a scientific panel of experts that aims to help nations use natural resources , Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States ...
's Metal Stocks in Society report, the global per capita stock of copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita). 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
furnace A furnace is a structure in which heat is produced with the help of combustion. Furnace may also refer to: Appliances Buildings * Furnace (house heating): a furnace , or a heater or boiler , used to generate heat for buildings * Boiler Poland ...
and then and cast into
billets A billet is a living quarters to which a soldier A soldier is a person who is a member of a professional army. A soldier can be a Conscription, conscript, volunteer, Enlisted rank, enlisted, non-commissioned officer, or an Officer (armed ...
and
ingot An ingot is a piece of relatively pure material, usually metal, that is Casting, cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products. Ingots usually require a second procedure ...
s; lower-purity scrap is refined by
electroplating Electroplating is a general name for processes that produce a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric current. The part to be coated acts as the cathode ...
in a bath of
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
.


Alloys

Numerous copper
alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts Elec ...
s have been formulated, many with important uses.
Brass Brass is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appea ...

Brass
is an alloy of copper and
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
.
Bronze Bronze is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appear ...

Bronze
usually refers to copper-
tin Tin is a with the Sn (from la, ) and  50. Tin is a silvery-colored metal that characteristically has a faint yellow hue. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent ...

tin
alloys, but can refer to any alloy of copper such as
aluminium bronze Aluminium bronze is a type of bronze Bronze is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polish ...
. Copper is one of the most important constituents of silver and
karat The fineness of a precious metal Precious metals are rare, naturally occurring metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or f ...
gold solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys. Some lead-free solders consist of tin alloyed with a small proportion of copper and other metals. The alloy of copper and
nickel Nickel is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

nickel
, called
cupronickel Cupronickel or copper-nickel (CuNi) is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fracture ...
, 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, alloys of copper and
silver Silver is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical ele ...

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. 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. Alloys of copper with aluminium (about 7%) have a golden color and are used in decorations. ''
Shakudō ''Shakudō'' (赤銅) is a Japanese Japanese may refer to: * Something from or related to Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a country A country is a ...
'' is a Japanese decorative alloy of copper containing a low percentage of gold, typically 4–10%, that can be
patina Patina (or ) is a thin layer that variously forms on the surface of , , and similar ( produced by oxidation or other chemical processes), or certain s, and wooden (sheen produced by age, wear, and polishing), or any similar acquired change ...

patina
ted to a dark blue or black color.


Compounds

Copper forms a rich variety of compounds, usually with
oxidation state The oxidation state, or oxidation number, is the hypothetical charge Charge or charged may refer to: Arts, entertainment, and media Films * ''Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * Charge (David Ford album), ''Charge ...
s +1 and +2, which are often called ''cuprous'' and ''cupric'', respectively. Copper compounds, whether organic complexes or
organometallic Organometallic chemistry is the study of organometallic compounds, chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any subst ...
s, promote or catalyse numerous chemical and biological processes.


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 A halide is a binary phase, of which one part is a halogen atom and the other part is an chemical element, element or radical (chemistry), radical that is less electronegative (or more electropositive) than the halogen, to make a, e.g., fluoride, ...
s. Both
cuprous Copper is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same nu ...
and cupric oxides are known. Among the numerous
copper sulfideCopper sulfides describe a family of chemical compounds and minerals with the formula CuxSy. Both mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Eart ...
s, important examples include copper(I) sulfide and copper(II) sulfide. Cuprous halides with copper(I) fluoride, fluorine, copper(I) chloride, chlorine, copper(I) bromide, bromine, and copper(I) iodide, iodine are known, as are cupric halides with copper(II) fluoride, fluorine, copper(II) chloride, chlorine, and copper(II) bromide, bromine. Attempts to prepare copper(II) iodide yield only copper(I) iodide and iodine. :2 Cu2+ + 4 I → 2 CuI + I2


Coordination chemistry

Copper forms coordination complexes with ligands. In aqueous solution, copper(II) exists as . 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. A simplified equation is: :Cu2+ + 2 OH → Cu(OH)2 Ammonia solution, Aqueous ammonia results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, forming Schweizer's reagent, tetraamminecopper(II): : + 4 NH3 → + 2 H2O + 2 OH Many other oxyanions form complexes; these include copper(II) acetate, copper(II) nitrate, and copper(II) carbonate. Copper(II) sulfate forms a blue crystalline pentahydrate, the most familiar copper compound in the laboratory. It is used in a
fungicide Fungicides are biocidal chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by hav ...
called the Bordeaux mixture. Polyols, 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. Schweizer's reagent and related complexes with ethylenediamine and other amines dissolve cellulose. Amino acids form very stable chelate complexes with copper(II). Many wet-chemical tests for copper ions exist, one involving potassium ferrocyanide, which gives a brown precipitate with copper(II) salts.


Organocopper chemistry

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 alkynes or organolithium compound, organolithium reagents; 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 and the Sonogashira coupling. Nucleophilic conjugate addition, Conjugate addition to Alpha-beta Unsaturated carbonyl compounds, enones and carbometalation, carbocupration of alkynes can also be achieved with organocopper compounds. Copper(I) forms a variety of weak complexes with alkenes and carbon monoxide, especially in the presence of amine ligands.


Copper(III) and copper(IV)

Copper(III) is most often found in oxides. A simple example is potassium cuprate, KCuO2, a blue-black solid. The most extensively studied copper(III) compounds are the cuprate superconductors. Yttrium barium copper oxide (YBa2Cu3O7) consists of both Cu(II) and Cu(III) centres. Like oxide, fluoride is a highly base (chemistry), basic anion and is known to stabilize metal ions in high oxidation states. Both copper(III) and even copper(IV) fluorides are known, Potassium hexafluorocuprate(III), K3CuF6 and Caesium hexafluorocuprate(IV), Cs2CuF6, respectively. Some copper proteins form oxo complexes, which also feature copper(III). With tetrapeptides, purple-colored copper(III) complexes are stabilized by the deprotonated amide ligands. Complexes of copper(III) are also found as intermediates in reactions of organocopper compounds. For example, in the Kharasch–Sosnovsky reaction.


History

A timeline of copper illustrates how this metal has advanced human civilization for the past 11,000 years.


Prehistoric


Copper Age

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 BC in the Middle East; a copper pendant was found in northern Iraq that dates to 8700 BC. Evidence suggests that gold and meteoric iron (but not smelted iron) were the only metals used by humans before copper. The history of copper metallurgy is thought to follow this sequence: First, cold forming, cold working of native copper, then Annealing (metallurgy), annealing,
smelting Smelting is a process of applying heat to ore in order to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, silver, iron-making, iron, copper ...
, and, finally, lost-wax casting. In southeastern Anatolia, all four of these techniques appear more or less simultaneously at the beginning of the Neolithic c. 7500 BC. Copper smelting was independently invented in different places. It was probably discovered in China before 2800 BC, in Central America around 600 AD, and in West Africa about the 9th or 10th century AD. Investment casting was invented in 4500–4000 BC in Southeast Asia and carbon dating has established mining at Alderley Edge Mines, Alderley Edge in Cheshire, UK, at 2280 to 1890 BC. Ötzi the Iceman, a male dated from 3300 to 3200 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. Experience with copper has assisted the development of other metals; in particular, copper smelting led to the discovery of bloomery, iron smelting. Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC.Pleger, Thomas C. "A Brief Introduction to the Old Copper Complex of the Western Great Lakes: 4000–1000 BC",
Proceedings of the Twenty-seventh Annual Meeting of the Forest History Association of Wisconsin
', Oconto, Wisconsin, 5 October 2002, pp. 10–18.
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 BC.


Bronze Age

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. Bronze artifacts from the Vinča culture date to 4500 BC. Sumerian and Ancient Egypt, Egyptian artifacts of copper and bronze alloys date to 3000 BC. The Bronze Age began in Southeastern Europe around 3700–3300 BC, in Northwestern Europe about 2500 BC. It ended with the beginning of the Iron Age, 2000–1000 BC in the Near East, and 600 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.


Ancient and post-classical

In Greece, copper was known by the name (χαλκός). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as ''aes Cyprium'', ''aes'' being the generic Latin term for copper alloys and ''Cyprium'' from
Cyprus Cyprus ; tr, Kıbrıs (), officially called the Republic of Cyprus,, , lit: Republic of Cyprus is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or politi ...

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. Copper was first mined in ancient Britain as early as 2100 BC. Mining at the largest of these mines, the Great Orme, continued into the late Bronze Age. Mining seems to have been largely restricted to supergene (geology), supergene ores, which were easier to smelt. The rich copper deposits of Cornwall seem to have been largely untouched, in spite of extensive
tin Tin is a with the Sn (from la, ) and  50. Tin is a silvery-colored metal that characteristically has a faint yellow hue. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent ...

tin
mining in the region, for reasons likely social and political rather than technological. In North America, copper mining began with marginal workings by Native Americans. Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600. Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD. Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century. 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 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 Cyprus ; tr, Kıbrıs (), officially called the Republic of Cyprus,, , lit: Republic of Cyprus is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or politi ...

Cyprus
and in Central Europe. The gates of the Temple of Jerusalem used Corinthian bronze treated with depletion gilding. The process was most prevalent in Alexandria, where alchemy is thought to have begun. In ancient India, copper was used in the holistic medical science Ayurveda for surgical instruments and other medical equipment. Ancient Egyptians (Old Kingdom, ~2400 BC) used copper for sterilizing wounds and drinking water, and later to treat headaches, burns, and itching.


Modern

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. It was referred to as the nation's treasury; Sweden had a History of copper currency in Sweden, copper backed currency. Copper is used in roofing, currency, and for photographic technology known as the daguerreotype. Copper was used in Renaissance sculpture, and was used to construct the
Statue of Liberty The Statue of Liberty (''Liberty Enlightening the World''; French: ''La Liberté éclairant le monde'') is a List of colossal sculpture in situ, colossal neoclassical sculpture on Liberty Island in New York Harbor in New York City, in the Un ...

Statue of Liberty
; copper continues to be used in construction of various types. 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. The Norddeutsche Affinerie in Hamburg was the first modern
electroplating Electroplating is a general name for processes that produce a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric current. The part to be coated acts as the cathode ...
plant, starting its production in 1876. The German scientist Gottfried Osann invented powder metallurgy in 1830 while determining the metal's atomic mass; around then it was discovered that the amount and type of alloying element (e.g., tin) to copper would affect bell tones. 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. 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 Souhwest 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. 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. 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.


Applications

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 Bronze is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appear ...

bronze
(5% of total use). For more than two centuries, copper paint has been used on boat hulls to control the growth of plants and shellfish. A small part of the copper supply is used for nutritional supplements and fungicides in agriculture. Machining of copper is possible, although alloys are preferred for good machinability in creating intricate parts.


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 Aluminium (aluminum in and ) is a with the  Al and  13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity towards , and of on the surface when exposed to air ...

aluminium
is often preferred. Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronics circuitry, and countless types of electrical equipment. Electrical wiring is the most important market for the copper industry. 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. Many electrical devices rely on copper wiring because of its multitude of inherent beneficial properties, such as its high
electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current An electric current is a stream of charged particle In p ...
, tensile strength,
ductility Ductility is a mechanical property commonly described as a material's amenability to drawing Drawing is a form of visual art The visual arts are art forms such as painting Painting is the practice of applying paint, pigment, c ...

ductility
, creep (deformation) resistance, corrosion resistance, low thermal expansion, high thermal conductivity, ease of soldering, malleability, and ease of installation. 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. The new wiring was implicated in a number of house fires and the industry returned to copper.


Electronics and related devices

Integrated circuits and printed circuit boards increasingly feature copper in place of aluminium because of its superior electrical conductivity; heat sinks and heat exchangers use copper because of its superior heat dissipation properties. Electromagnets, vacuum tubes, cathode ray tubes, and magnetrons in microwave ovens use copper, as do waveguides for microwave radiation.


Electric motors

Copper's superior Copper wire and cable#Electrical conductivity, conductivity enhances the efficiency of electrical motor (device), motors. 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. 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, are enabling general-purpose induction motors to meet and exceed National Electrical Manufacturers Association (NEMA) premium efficiency standards.


Renewable energy production


Architecture

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 gutters, downspouts, domes, spires, vaults, and doors 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 joints, 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 The metal's distinctive natural green
patina Patina (or ) is a thin layer that variously forms on the surface of , , and similar ( produced by oxidation or other chemical processes), or certain s, and wooden (sheen produced by age, wear, and polishing), or any similar acquired change ...

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. It can be a mixture of carbonate and sulfate compounds in various amounts, depending upon environmental conditions such as sulfur-containing acid rain. 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. Copper has excellent brazing and soldering properties and can be welded; the best results are obtained with gas metal arc welding.


Antibiofouling

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 barnacles and mussels. 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 conditionsEdding, 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. and have strong structural and corrosion-resistant properties in marine environments.


Antimicrobial

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, Severe acute respiratory syndrome coronavirus 2, SARS-Cov-2, and Fungus, fungi).Copper Touch Surfaces
. Copper Touch Surfaces. Retrieved on 8 November 2011.
Indians have been using copper vessels since ancient times for storing water, even before modern science realized its antimicrobial properties. Some copper alloys were proven to kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly. The United States Environmental Protection Agency (EPA) has approved the registrations of these copper alloys as "antimicrobial materials with public health benefits"; 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 (for a comprehensive list, see: Antimicrobial copper-alloy touch surfaces#Approved products). Copper doorknobs are used by hospitals to reduce the transfer of disease, and Legionnaires' disease is suppressed by copper tubing in plumbing systems. Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil, as well as being called for in the US, and in the subway transit system in Santiago, Chile, where copper-zinc alloy handrails were installed in some 30 stations between 2011 and 2014. Textile fibers can be blended with copper to create antimicrobial protective fabrics.


Speculative investing

Copper may be used as a speculative investment due to the predicted increase in use from worldwide infrastructure growth, and the important role it has in producing wind turbines, solar panels, and other renewable energy sources. Another reason predicted demand increases is the fact that electric cars contain an average of 3.6 times as much copper as conventional cars, although the effect of electric cars on copper demand is debated. Some people invest in copper through copper mining stocks, Exchange-traded fund, ETFs, and Futures contract, futures. Others store physical copper in the form of copper bars or rounds although these tend to carry a higher premium in comparison to precious metals. Those who want to avoid the premiums of copper bullion alternatively store old copper wire, copper tubing or American Penny (United States coin), pennies made before 1982.


Folk medicine

Copper is commonly used in jewelry, and according to some folklore, copper bracelets relieve arthritis symptoms. In one trial for osteoarthritis and one trial for rheumatoid arthritis, no differences is found between copper bracelet and control (non-copper) bracelet. No evidence shows that copper can be absorbed through the skin. If it were, it might lead to Copper toxicity, copper poisoning.


Compression clothing

Recently, some compression bandage, compression clothing with inter-woven copper has been marketed with health claims similar to the folk medicine claims. Because compression clothing is a valid treatment for some ailments, the clothing may have that benefit, but the added copper may have no benefit beyond a placebo effect.


Degradation

''Chromobacterium violaceum'' and ''Pseudomonas fluorescens'' can both mobilize solid copper as a cyanide compound. The ericoid mycorrhizal fungi associated with ''Calluna'', ''Erica'' and ''Vaccinium'' can grow in metalliferous soils containing copper. The ectomycorrhizal fungus ''Suillus luteus'' protects young pine trees from copper toxicity. A sample of the fungus ''Aspergillus niger'' was found growing from gold mining solution and was found to contain cyano complexes of such metals as gold, silver, copper, iron, and zinc. The fungus also plays a role in the solubilization of heavy metal sulfides.


Biological role


Biochemistry

Copper proteins have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II). Copper is essential in the aerobic Cellular respiration, respiration of all eukaryotes. In mitochondria, it is found in
cytochrome c oxidase The enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the su ...
, which is the last protein in oxidative phosphorylation. Cytochrome c oxidase is the protein that binds the O2 between a copper and an iron; the protein transfers 8 electrons to the O2 molecule to reduce it to two molecules of water. Copper is also found in many superoxide dismutases, proteins that catalyze the decomposition of superoxides by converting it (by disproportionation) to oxygen and hydrogen peroxide: * Cu2+-SOD + O2 → Cu+-SOD + O2 (reduction of copper; oxidation of superoxide) * Cu+-SOD + O2 + 2H+ → Cu2+-SOD + H2O2 (oxidation of copper; reduction of superoxide) The protein
hemocyanin Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). ...
is the oxygen carrier in most mollusks and some arthropods such as the horseshoe crab (''Limulus polyphemus''). Because hemocyanin is blue, these organisms have blue blood rather than the red blood of iron-based
hemoglobin Hemoglobin or haemoglobin (spelling differences Despite the various English dialects Dialect The term dialect (from Latin , , from the Ancient Greek word , , "discourse", from , , "through" and , , "I speak") is used in two distinct way ...

hemoglobin
. Structurally related to hemocyanin are the laccases and tyrosinases. Instead of reversibly binding oxygen, these proteins hydroxylate substrates, illustrated by their role in the formation of lacquers.S.J. Lippard, J.M. Berg "Principles of bioinorganic chemistry" University Science Books: Mill Valley, CA; 1994. . The biological role for copper commenced with the appearance of oxygen in earth's atmosphere. 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. A unique tetranuclear copper center has been found in nitrous-oxide reductase. Chemical compounds which were developed for treatment of Wilson's disease have been investigated for use in cancer therapy.


Nutrition

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 mg per kg of body mass.


Absorption

Copper is absorbed in the gut, then transported to the liver bound to serum albumin, albumin. 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. Copper in the body normally undergoes enterohepatic circulation (about 5 mg a day, vs. about 1 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.


Dietary recommendations

The U.S. Institute of Medicine (IOM) 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 μg of copper for 0–6-month-old males and females, and 220 μg of copper for 7–12-month-old males and females. For both sexes, the RDAs for copper are: 340 μg of copper for 1–3 years old, 440 μg of copper for 4–8 years old, 700 μg of copper for 9–13 years old, 890 μg of copper for 14–18 years old and 900 μg of copper for ages 19 years and older. For pregnancy, 1,000 μg. For lactation, 1,300 μg. As for safety, the IOM also sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of copper the UL is set at 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes. 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 defined the same as in United States. For women and men ages 18 and older the AIs are set at 1.3 and 1.6 mg/day, respectively. AIs for pregnancy and lactation is 1.5 mg/day. For children ages 1–17 years the AIs increase with age from 0.7 to 1.3 mg/day. These AIs are higher than the U.S. RDAs. The European Food Safety Authority reviewed the same safety question and set its UL at 5 mg/day, which is half the U.S. value. For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For copper labeling purposes 100% of the Daily Value was 2.0 mg, but it was revised to 0.9 mg to bring it into agreement with the RDA. A table of the old and new adult daily values is provided at Reference Daily Intake.


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. Conversely, Wilson's disease causes an accumulation of copper in body tissues. 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.


Toxicity

Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, possibly due to redox cycling and the generation of reactive oxygen species that damage DNA. Corresponding amounts of copper salts (30 mg/kg) are toxic in animals. A minimum dietary value for healthy growth in rabbits has been reported to be at least 3 Parts per million, ppm in the diet. However, higher concentrations of copper (100 ppm, 200 ppm, or 500 ppm) in the diet of rabbits may favorably influence Feed conversion ratio, feed conversion efficiency, growth rates, and carcass dressing percentages. Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. Autosomal recessive mutations in copper transport proteins can disable these systems, leading to Wilson's disease with copper accumulation and cirrhosis of the liver in persons who have inherited two defective genes. Elevated copper levels have also been linked to worsening symptoms of Alzheimer's disease.


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 mg/m3. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1 mg/m3, time-weighted average. The IDLH (immediately dangerous to life and health) value is 100 mg/m3. Copper is a constituent of tobacco smoke. The tobacco plant readily absorbs and accumulates heavy metals, such as copper from the surrounding soil into its leaves. These are readily absorbed into the user's body following smoke inhalation. The health implications are not clear.


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


Peak copper

* Anaconda Copper * Antofagasta PLC * Codelco * El Boleo, El Boleo mine * Grasberg mine


References


Notes


Further reading

* * * Current Medicinal Chemistry, Volume 12, Number 10, May 2005, pp. 1161–1208(48) Metals, Toxicity and Oxidative Stress *
Material: Copper (Cu), bulk
MEMS and Nanotechnology Clearinghouse. *


External links



at ''The Periodic Table of Videos'' (University of Nottingham)
Copper and compounds fact sheet
from the National Pollutant Inventory of Australia
Copper.org
– official website of the Copper Development Association with an extensive site of properties and uses of copper
Price history of copper, according to the IMF
{{good article Copper, Chemical elements Transition metals Biology and pharmacology of chemical elements Dietary minerals Electrical conductors Cubic minerals Crystals in space group 225 Native element minerals Symbols of Arizona Chemical elements with face-centered cubic structure