Copper

Copper (pronounced kop-er)

(1) A malleable, ductile, metallic element having a characteristic reddish-brown color, occurring as the free metal, copper glance, and copper pyrites: used as an electrical and thermal conductor and in such alloys as brass and bronze.

(2) As a color, a metallic, reddish brown.

(3) A slang term for a coin (usually of a smaller denomination) composed of copper, bronze etc.

(4) A slang term for a hedge (archaic).

(5) A slang term for a police or other law-enforcement officer, now usually as the shortened “cop”.

(6) In lepidopterology, any of several butterflies of the family Lycaenidae, as Lycaena hypophleas (American copper), having copper-colored wings spotted and edged with black.

(7) In slang and informal use, a tool or any of the various specialized items made from copper, where the use of copper is either traditional or vital to the function of the item.

(8) In historic UK & Commonwealth use, a large kettle (now usually made of cast iron), used for cooking or to boil the laundry (archaic and functionally extinct); a once popular term for any container made of copper.

(9) To cover, coat, or sheathe with copper.

Pre 1000: From the Middle English coper & copper, from the Old English coper & copor, from the Late Latin cuprum (copper), from the Latin aes Cyprium (literally “Cyprian brass” (ie metal from the island of Cyprus)), from the Ancient Greek Κύπρος (Kúpros) (Cyprus).  It was cognate with the Dutch koper (copper), the Old Norse koparr (copper), the German Kupfer (copper) and the Icelandic kopar (copper).  The alternative spelling coper (a hangover from the Middle English) is obsolete.  Copper & are nouns, verbs & adjectives, copperas is a noun, coppered & coppering are verbs & adjectives and coppery, cupric, cupreous & cuprous are adjectives; the noun plural is coppers.

In the Ancient Greek there was khalkos (ore, copper, bronze), a direct borrowing of the primitive Indo-European word meaning "ore, copper, bronze" and familiar in the Sanskrit ayah and the Latin aes.  In Classical Latin aes originally was used of copper but as technology evolved, this was extended to bronze (its alloy with tin) and because bronze was used much more than pure copper, the word's primary sense shifted to the alloy and a new word evolved for "copper," from the Latin form of the name of the island of Cyprus, where the copper mines were located.  Cyprus being the birthplace of Aphrodite (Venus), this led (in the way mythology adapted to the times) to the association of by alchemists of Aphrodite with copper.  Aes passed into the proto-Germanic where originally no linguistic distinction existed between copper from its alloys while in English it became “ore”.  In Latin vernacular, aes was used also to mean “cash, coin, debt, wages” in many figurative expressions. The chemical symbol Cu is from cuprum, from the Ancient Greek Κύπρος (Kúpros) (Cyprus).

The use to describe coins made of (or appearing to be made of) copper dates from the 1580s while to refer to vessels (jars, tubs, pots etc) made from the metal it came into use in the 1660s, the adjective cupreous (consisting of or containing copper (from the Late Latin cupreus (of copper), from cuprum (an, alternative form of cyprum (copper)) emerging in parallel.   The adjectival use in the sense of “made from or resembling copper” emerged in the 1570, a development from the verb, in use since the 1520s.  The alloy copper-nickel was first used to mint coins in 1728.  The trade of coppersmithing, practiced by the coppersmith (artisan who works in copper), was a creation of the early fourteenth century and was, as was practice at the time, soon used as a surname.  The noun copperplate (also copper-plate) described a "plate of polished copper, engraved and etched" dates from the 1660s and was later used figuratively to describe designs (wallpaper, woodcuts, carvings, carpet etc) with some resemblance to the styled metal.  Perhaps surprisingly, the adjectival sense in the sense of an allusion to the reddish-brown color isn’t documented until the turn of the nineteenth century (“cupric” used thus in 1799 and "copper-colored" after 1804) although it may earlier have been part of one or more oral traditions.

Symbol: Cu.
Atomic number: 29.
Atomic weight: 63.546.
Valency: 1 or 2.
Relative density: 8.96.
Specific gravity: 8.92 at 20°C.
Melting point: 1084.87±+0.2°C.
Boiling point: 2563°C

In an example of the way English must seem strange to speakers of more apparently logically languages, the use of “cop” as a slang term for “police or other law-enforcement officer” is a shortening of “copper” but that is etymologically unrelated to the metal, the use of “copper” to describe policemen (at a time all were men” derived from the English “cop”.  The construct was cop (to take, capture, seize) +‎ -er (the agent suffix).  Cop is of uncertain origin but the most likely link is with the Middle English coppen & copen, from the Old English copian (to plunder; pillage; steal) although some etymologists have also suggested the Middle French caper (to capture), from the Latin capiō (to seize, grasp) or the Dutch kapen (to seize, hijack), from the Old Frisian kāpia (to buy), source of the Saterland Frisian koopje and the North Frisian koope.  A perhaps related form was the Middle English copen (to buy), from the Middle Dutch copen.

New York's Statute of Liberty with the copper skin colored as it would have appeared in France, prior to being shipped to the US for erection in  in 1886 (left) and as it appeared decades later, the metal showing the effects of oxidization (right).  

The expression “to cop” was thus used in the sense of “to steal” but also (as a transitive verb) “to (be forced to) take; to receive; to shoulder; to bear, especially blame or punishment for a particular instance of wrongdoing”, hence the expressed notions of “cop the blame”, “cop an injury” etc.  It was the association with crime and violence which in the nineteenth century saw "copper" (one who cops (apprehends) the criminal) adopted in the UK (first documented in 1846) to describe what were then the still relatively novel (in the sense of a structured, publicly-funded force) policemen and as “cop”, the world spread world-wide.  Cop also had a mono-syllabic appeal to many sub-cultures who took up the sense of “to obtain; acquire; purchase”; it was used (1) by drug users to express acquisition of narcotics, (2) among anoraks (train-spotters, plane-spotters, bird-watchers etc) to mark the observation and recording of something unique or at least rare and (3) by those living off immoral earnings (pimps), to speak of the recruitment of a prostitute to the lineup.  There was also the alleged slang form “fair cop”, said to be used by criminals (to cops) when admitting guilt although whether this was as common in real life as it was in the imaginations of crime writers isn’t known although “bent copper” (a corrupt police officer) still enjoys some currency.

JTC Roofing in the UK provided a chart using the Statute of Liberty to illustrate the natural process by which copper gradually changes in color from the original reddish-brown to green, a chemical reaction between the metal and the oxygen in the atmosphere, something known as oxidation.  In an aesthetic sense, the transition to green is part of copper’s charming patina but it’s also functional, providing a protective coating which protects surface deterioration and in this it differs from a ferrous metal like iron which, under oxidation, becomes rusted, the rust eating into the material.  The result can be seen in the light bluish-green copper facades which adorn many copper rooftops and structures and the pallette evolves over years before the familiar green tint achieves a final hue, something influenced also by atmospheric and climatic conditions.

The patination of copper induced by oxidation can be emulated in hair colors: Lindsay Lohan demonstrates. 

Helpfully, World of Chemicals has explained the chemistry.  When in 1886 the Statute of Liberty was assembled and erected after being shipped from France, it was a quite dull brown, reflecting the process of oxidation which had already taken from the metal the shininess which the coppersmiths and engineers would have seen when first working on the pates in Paris and it would take another 30-odd years of weathering before the now familiar color settled.  This patination is fine if a structure for decades remains untouched but in some uses in architecture (especially roofs which are vulnerable to damage), it’s sometimes necessary to replace copper panels which can result in an unsightly patchwork of colors.  For this reason, the industry has developed processes of pre-patination which can render copper panels with specific degrees of patination to match a sample of the damaged item, thus providing a close color-match.

Because of its location and the era in which it has stood, the particular path to verdigris (from the French vert-de-gris (literally “green of Greece”)) assumed by the Statute of Liberty was influenced by the unique environmental conditions.  Although the process is linguistically encapsulated as “oxidation”, it's not a simple single reaction between copper and oxygen because the generated green oxide continues to react to make copper carbonates, copper sulphide, and copper sulphate.  Initially, the copper reacts with oxygen from the air in a redox reaction, the metal donating electrons to oxygen, which oxidises the copper and reduces the oxygen, the copper oxide continuing to react with oxygen to form copper oxide.  However, for many of the decades in which the statute stood, the atmosphere contained much sulphur from the burning of coal and this induced another reaction which produced copper sulphide (black) which reacts with atmospheric carbon dioxide and hydroxide ions from water vapour, forming three compounds all of which exist in shades of blue or green.  The speed at which the patina develops and evolution of the colour depends on factors like temperature, humidity and air pollution, not just the presence of oxygen and carbon dioxide and, in another time, in another place, things would have unfolded differently.

Statue of Liberty (1962), silkscreen print by Andy Warhol. 

Andy Warhol (1928-1987) produced a few depictions of the Statute of Liberty, mostly variations of the familiar theme made famous by his prints of Marilyn Monroe (1926–1962) but one with a touch of something original was a silkscreen rendering in 1962 of multiple tiled images in 3D.  At auction by Christies (New York) in 2012, it sold for US$43.8 million, part of a collection of contemporary art that realized an encouraging US$412.3 million, regarded at the time as a sign the market was recovering from the shock of the global financial crisis (GFC); the US Federal Reserve (The Fed) must have been pleased to see all that quantitative easing being spent wisely.  Even so, it didn’t set a record for a Warhol, Eight Elvises sold in a private sale 2008 for a reputed US$100 million although the auction house did throw in a pair of 3D glasses with the catalogue so there was that.  In 2013, another Warhol from 1963 set a pop-art record which stands today, Silver Car Crash (Double Disaster) selling at auction for US$105.4 million.