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The discovery of copper (Cu) dates back to prehistoric times and is believed to have been mined for over 5000 years. It is found native and in the minerals cuprite (Cu2O), malachite (Cu2CO3(OH)2), azurite (Cu3(CO3)2(OH)2), chalcopyrite (CuFeS2), and bornite (Cu5FeS4) and often is part of widely used metal alloys such as sterling silver. Of the ores that copper can be smelted from, sulfides, oxides, and carbonates are the most important.
Copper has a face-centered cubic crystal structure. It is yellowish red in physical appearance and has a bright metallic luster when polished. It is tough, ductile, and malleable. Copper is the best conductor of electricity after silver, having a conductivity 97% that of silver.
Copper is generally corrosion-resistant to rural, marine, and industrial atmospheres. It is also resistant to various waters, saline solutions, soils, non-oxidizing mineral and organic acids, and caustic solutions. However, copper is attacked by oxidizing acids like Nitric acid, moist ammonia, and halogens, sulfides, and solutions containing ammonia ions.
There are numerous copper series in production, including standard wrought grades represented by the designations C10XXX to C15XXX and standard casts designations C80XXX to C81100. The highest purity grade is oxygen-free-electronic copper which is at least 99.99% pure copper.
Copper has a great number of applications. A summary of these includes bus bars, commutators, terminals, waveguides, electric wire, power transmission lines, motor windings, printed circuits, springs, water pipes, and tubing, heat exchangers, building products, gaskets, and fasteners of many kinds.
Due to its high conductivity and relatively low price (compared to silver), copper was instrumental in the development of information science. Copper connections still exist across much of the internet, although faster fiber-optic connections are now commonplace.
This article was updated on 12th February, 2020.