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, river, United States
Copper, river, c.300 mi (480 km) long, rising in the Wrangell Mts., SE Alaska, and flowing S through the Chugach Mts. to the Gulf of Alaska. Copper deposits near the upper river, long mined by natives, attracted the attention of Russians and later Americans, but exploration was difficult because of the river's currents and the glaciers near its mouth. The great Kennecott mine (discovered 1898; abandoned 1938) was made reachable by the building of the Copper River and Northwestern RR from Cordova, which followed the river along part of its lower valley. Today the Copper is noted for its salmon.


, chemical element
copper, metallic chemical element; symbol Cu [Lat. cuprum=copper]; at. no. 29; at. wt. 63.546; m.p. 1,083.4℃; b.p. 2,567℃; sp. gr. 8.96 at 20℃; valence +1 or +2. Copper and some of its alloys have been used by humanity since the Bronze Age. One of the first metals known to humans, copper was smelted as long ago as c. 5000 B.C. Cyprus, from which the metal's name originally comes, was a major source of copper in the ancient world.


Copper is a reddish metal with a face-centered cubic crystalline structure. It is malleable, ductile, and an extremely good conductor of both heat and electricity. It is softer than iron but harder than zinc and can be polished to a bright finish. It is found in Group 11 of the periodic table, together with silver and gold. Copper has low chemical reactivity. In moist air it slowly forms a greenish surface film (usually a mixture of carbonate, sulfate, hydroxide, and oxide) called patina; this coating protects the metal from further attack. Copper dissolves in hot concentrated hydrochloric or sulfuric acid but is little affected by cold solutions of these acids; it also dissolves in nitric acid. Salt water corrodes copper, forming a chloride.


The most important chemical compound of copper is copper sulfate pentahydrate, also called bluestone or blue vitriol. Other compounds include Paris green, Bordeaux mixture, a cyanide, a chloride, oxides, and a basic carbonate. Verdigris is basic copper acetate.

Sources and Ores

Small amounts of copper are found uncombined, particularly near Lake Superior in Michigan. Copper ores are found in various parts of the world. In the United States (the chief producer of copper) ores are mined in Arizona, Utah, Montana, New Mexico, Nevada, and Michigan. Copper ores are also found in Canada, South America (in Chile and Peru), S central Africa, Russia (in the Ural Mts.), and to a limited extent in Europe and the British Isles.

The principal ore of copper is chalcopyrite, a sulfide of copper and iron, also called copper pyrite. Other important ores are chalcocite, or copper glance, a shiny lead-gray copper sulfide; bornite, a lustrous reddish-brown sulfide of copper and iron; cuprite, a red cuprous oxide ore; and malachite, a bright green carbonate ore. Azurite is a blue crystalline basic carbonate of copper found with other copper ores. Chrysocolla is a bluish-green copper silicate ore. Another important source of copper is secondary (scrap) copper, which is produced from discarded copper and copper alloys.

Commercial Preparation

Copper metal is prepared commercially in various ways. Copper sulfide ores, usually containing only 1% to 2% copper, are concentrated to 20% to 40% copper by the flotation process. They are then usually roasted to remove some of the sulfur and other impurities, and then smelted with iron oxide in either a blast furnace or a reverberatory furnace to produce copper matte, a molten solution of copper sulfide mixed with small amounts of iron sulfide. The matte is transferred to a converter, where it is treated by blowing air through it to remove the sulfur (as sulfur dioxide, a gas) and the iron (as a slag of ferrous oxide). The resulting copper is 98% to 99% pure; it is called blister copper because its surface is blistered by escaping gases when it solidifies during casting.

Most copper is further purified by electrolysis. The blister copper is refined in a furnace and cast into anodes. Thin sheets of pure copper are used as cathodes. A solution of copper sulfate and sulfuric acid is used as the electrolyte. When the anode and cathode are immersed in the electrolyte and an electric current is passed, the anode is dissolved in the electrolyte and pure copper metal is deposited on the cathode. Soluble impurities, usually nickel and arsenic, remain dissolved in the electrolyte. Insoluble impurities, often including silver, gold, and other valuable metals, settle out of the electrolyte; they may be collected and purified.

Copper oxide ores are usually treated by a different process, called leaching, in which the copper in the ore is dissolved in a leaching solution (usually dilute sulfuric acid); pure copper is recovered by electrolysis. Alternatively, the solution is treated with iron to precipitate the so-called cement copper, which is impure.

Importance and Uses

Copper is present in minute amounts in the animal body and is essential to normal metabolism. It is a component of hemocyanin, the blue, oxygen-carrying blood pigment of lobsters and other large crustaceans. It is needed in the synthesis of hemoglobin, the red, oxygen-carrying pigment found in the blood of humans, although it is not a component of hemoglobin.

The chief commercial use of copper is based on its electrical conductivity (second only to that of silver); about half the total annual output of copper is employed in the manufacture of electrical apparatus and wire. Copper is also used extensively as roofing, in making copper utensils, and for coins and metalwork. Copper tubing is used in plumbing, and, because of its high heat conductivity, in heat-exchanging devices such as refrigerator and air-conditioner coils. Powdered copper is sometimes used as a pigment in paints. An important use of copper is in alloys such as brass, bronze, gunmetal, Monel metal, and German silver. Compounds of copper are widely used as insecticides and fungicides; as pigments in paints; as mordants (fixatives) in dyeing; and in electroplating.

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A metal with good electrical conductivity, used for roofing, flashing, hardware and plumbing applications; when exposed to air, copper oxidizes and develops a greenish “patina” that halts corrosion. See also: Metal
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a river in Alaska. Length, 500 km; basin area, more than 60,000 sq km.

The Copper rises in the northern slopes of the Wrangell Mountains and falls into the Gulf of Alaska of the Pacific Ocean. In the lower course the Copper River cuts through the Chugach Mountains. It is fed primarily by snow and glaciers, with high water extending from June through August. The average discharge of water at Chitina is approximately 1,000 cu m per sec. For half of the year the river is covered with ice. Located on the Copper River is the settlement of Copper Center, the center of an ore-mining region that is linked by railroad with the port of Cordova on the Gulf of Alaska.



(Cu), a chemical element of group I of Mendeleev’s periodic system. Atomic number, 29; atomic weight, 63.546. A soft, malleable metal of red color. Natural copper consists of a mixture of two stable isotopes: 63Cu (69.1 percent) and 65Cu (30.9 percent).

History. Copper is one of the metals that has been known since antiquity. Man’s early familiarity with copper was due to the occurrence of the metal in nature as native copper, often found in single masses of great size. Copper and its alloys played an important role in the development of material culture. Owing to the ease of the reductibility of its oxides and carbonates, copper was apparently the first metal that man learned to obtain by reduction from the oxygen compounds contained in the ores. The Latin name of copper, cuprum, is derived from the name of the island of Cyprus, where the ancient Greeks mined the copper ores.

In antiquity, the copper-bearing rock was heated over a campfire and then rapidly cooled, which resulted in the rock cracking apart. Reduction processes are possible even under such conditions. Subsequently, the reduction was carried out in bonfires containing large quantities of charcoal with the air being blown by means of pipes and bellows. The bonfires were surrounded by walls, which were gradually made higher, thus leading to the development of the shaft furnace. The reduction processes were later replaced by the oxidative fusion of sulfide copper ores, which resulted in the production of the intermediate products, including copper matte (a sulfide alloy), in which the copper is concentrated, and slag (an oxide alloy).

Occurrence in nature. The mean content in the earth’s crust (clarke) of copper is 4.7 X 10-3 percent by weight. The lower part of the earth’s crust, which consists of basic rocks, contains more copper (1 X 10-2 percent) than the upper part (2 X 10-3 percent), in which granites and other acidic igneous rocks predominate. Copper migrates rapidly both in the hot waters deep within the earth and in the cold solutions of the biosphere. Hydrogen sulfide precipitates various industrially important sulfides of copper out of natural waters. The sulfides, phosphates, sulfates, and chlorides predominate among the numerous copper minerals. Native copper, carbonates, and oxides are also known.

Copper is an important element of living processes, participating in many physiological processes. The mean copper content in living matter is 2 X 10-4 percent; however, organisms that concentrate copper are also known. In taiga areas and in humid climates copper is relatively easily leached out from acidic soils. This leads to a deficiency of copper and results in diseased plants and animals, especially in sands and peat bogs. In steppes and deserts, with their characteristic weakly alkaline solutions, copper has low mobility; in localities with copper deposits, there is an excess of copper in the soil and plants, leading to various sicknesses in domestic animals.

River water contains very little copper (1 X 10-7 percent). Copper carried into the oceans by streams is relatively rapidly deposited in marine silts. For this reason, clays and shales are somewhat enriched in copper (5.7 X 10-3 percent), whereas seawater is sharply deficient in copper (3 X 10-7 percent).

Significant accumulation of copper occurred in the silts of the seas of the preceding geologic epochs, which led to the formation of deposits (for example, at Mansfeld in the German Democratic Republic). Copper also migrates vigorously in the subterranean waters of the biosphere, and the accumulation of copper ores in sandstones is related to these processes.

Physical and chemical properties. The color of copper is red; in fractures it is pink, and on transmission through thin layers, greenish blue. The metal has a face-centered cubic lattice with the parameter a = 3.6074 angstroms (Å). The density is 8.96 g/cm3 (20°C). The atomic radius is 1.28 Å, and the ionic radii are Cu+ 0.98 Å and Cu+ + 0.80 Å. The melting point is 1083°C, and the boiling point is 2600°C. The specific heat is (at 20°C) 385.48 joules/(kg.°K), that is, 0.092 calorie/(g.°C). The most important and widely used properties of copper are the metal’s high heat conductivity, which at 20°C is 394.279 watts/m·°K, or 0.941 calorie/(cm · sec · °C), and low electrical resistance, which at 20°C is 1.68 X 10-8 ohm-m. The thermal coefficient of linear expansion is 17.0 X 10-6. The vapor pressure of copper is negligible; the pressure of 133.322 newtons/ m2 (that is, 1 mm Hg) is attained only at 1628°C. Copper is diamagnetic; its atomic magnetic susceptibility is 5.27 X 10-6. The Brinell hardness is 350 meganewtons/ m2 (MN/m2), or 35 kilograms-force/mm2 (kgf/mm2); the tensile strength is 220 MN/m2, or 22 kgf/mm2; the relative elongation is 60 percent; and the modulus of elasticity is 132 X 103 MN/m2, or 13.2 X 103 kgf/mm2. Cold working increases the tensile strength to 400-450 MN/m2 but decreases the elongation to 2 percent and the electrical conductivity by 1-3 percent. Cold-worked copper should be annealed at 600°-700°C. Small admixtures of Bi (a few thousandths of a percent) and of Pb (a few hundredths of a percent) endow copper with red-shortness, whereas an admixture of S causes brittleness in the cold.

With respect to chemical properties, copper occupies an intermediate position between the elements of the first triad of group VIII and the alkali metals of group I of Mendeleev’s system. Copper, like Fe, Co, and Ni, tends to form complexes and gives colored compounds and insoluble sulfides. Its resemblance to the alkali metals is insignificant. Thus, copper forms a series of univalent (cuprous) compounds, but the bivalent (cupric) state is more characteristic. The cuprous salts are practically insoluble in water and are readily oxidized to bivalent copper compounds; the cupric salts, on the other hand, are readily soluble in water and completely dissociate in dilute solutions. Hydrated Cu2+ ions are blue. Compounds of trivalent copper are also known. Thus, the action of sodium peroxide on a solution of sodium cuprite, Na2CuO2, yields the oxide Cu2O4;a red powder that begins giving up oxygen at temperatures as low as 100°C. Cu2O3 is a strong oxidizing agent (for example, it displaces chlorine from hydrochloric acid).

The chemical activity of copper is not high. The compact metal does not react with dry air or oxygen at temperatures below 185°C. A green film of basic carbonate forms on the surface of copper in the presence of moisture and CO2. Heating copper in air leads to surface oxidation; CuO is formed below 375°C, and at temperatures between 375°C and 1100°C in incomplete oxidation a two-layer film is formed consisting of CuO at the top and Cu2O at the bottom. Moist chlorine reacts with copper already at ambient temperature to give CuCl2, which is readily soluble in water. Copper also combines readily with other halogens. It has a particular affinity for sulfur and selenium, and thus burns in sulfur vapors. Copper does not react with hydrogen, nitrogen, and carbon, even at high temperatures. The solubility of hydrogen in solid copper is insignificant, and at 400°C it constitutes 0.06 mg per 100 g of copper. Hydrogen and other combustible gases (CO, CH4) react at high temperatures with copper ingots containing Cu2O and reduce the copper to the metal with the formation of CO2 and water vapor. These products, being insoluble in copper, are evolved from the copper, forming cracks; this greatly decreases the mechanical properties of copper.

Passing NH3 over red-hot copper leads to the formation of Cu3N. Copper reacts with nitrogen oxides at temperatures of incandescence, in particular, with NO and N2O to give Cu2O and with NO2 to give CuO. The carbides of copper, Cu2C2 and CuC2, can be obtained by the action of acetylene on the ammonia solutions of copper salts. The normal electrode potential of copper for the reaction Cu2+ + 2e → Cu is equal to +0.337 V, and for the reaction Cu+ + e → Cu, to +0.52 V. For this reason copper is displaced from its compounds by the more electronegative elements (iron is used in industry) and does not dissolve in nonoxidizing acids. Copper dissolves in nitric acid with the formation of Cu(NO3)2 and nitrogen oxides, in hot concentrated H2SO4 with the formation of CuSO4 and SO2, and in hot dilute H2SO4 upon passing air through the solution. All copper salts are toxic.

Univalent copper and bivalent copper form numerous rather stable complex compounds. Examples of complex compounds of univalent copper are (NH4)2CuBr3; K3Cu(CN)4, which is a double-salt type complex; and [Cu{SC(NH2)}2]Cl. Examples of complex compounds of bivalent copper are CsCuCl3 and K2CuCl4, a double-salt type. The ammonia complex compounds of copper [Cu(NH3)4]SO4 and [Cu(NH3)2]SO4 are important in industry.

Production. Copper ores are characterized by a low copper content. For this reason, the finely ground ore undergoes concentration prior to smelting. This process involves the separation of the valuable minerals from the bulk of the gangue (worthless rock) to give a number of commercial concentrates (for example, copper, zinc, pyrites) and tailings.

In worldwide practice, 80 percent of the copper produced is extracted from the concentrates by pyrometallurgical methods, which are based on the smelting of the entire mass of the material. Because of the high affinity of copper for sulfur and of the components of the gangue and of iron for oxygen, copper is concentrated in molten sulfides (matte), while the oxides form the slag. On standing, the matte separates from the slag.

In most modern plants the smelting operation is carried out in reverberatory or electric furnaces. The processing space in reverberatory furnaces is horizontal. The hearth measures 300 m2 (30 m X 10 m), sometimes more. The heat required for smelting is produced by burning carbonaceous fuel (natural gas, fuel oil, or pulverized coal) in the gas space above the bath. In electric furnaces the heat is produced by passing an electric current through the molten slag; the current is supplied to the slag by immersed graphite electrodes.

However, both the reverberatory and the electric smelting methods, which are based on external sources of heat, are imperfect processes. The sulfides, which constitute the bulk of the copper concentrates, have a high heat-producing capacity. Therefore, smelting methods in which the heat of combustion of the sulfides is utilized (the oxidizing agents in these processes being preheated air, air enriched in oxygen, or industrial oxygen) are gaining increased acceptance. The predried particles of sulfide concentrate are blown by a jet of either oxygen or air into a furnace heated to a high temperature. The particles burn in the suspended state (oxygen-fluidized smelting). It is also possible to oxidize the sulfides in the liquid state. These processes are being intensively studied in the USSR and in Japan, Australia, and Canada and are becoming the main trend in the development of the pyrometallurgy of copper sulfide ores.

Sulfide ores rich in copper (2-3 percent Cu) and with a high sulfur content (35-42 percent sulfur) are sometimes sent directly for smelting in blast furnaces (furnaces with vertical processing space). In one kind of blast-furnace smelting (copper-sulfur smelting), small particles of coke are added to the charge thus reducing the SO 2 to elemental sulfur in the upper part of the furnace. In this process, the copper also accumulates in the matte.

The liquid matte resulting from smelting (mainly Cu2S and FeS) is poured into a converter, a revolving cylindrical drum made of sheets of steel and lined within by magnesite brick and equipped with lateral tuyeres for blowing air. Compressed air is blown through the matte. The mattes are converted in two stages. First, iron sulfide is oxidized and quartz is added to the converter in order to bind the iron oxides; converter slag is formed. The copper sulfide is then oxidized to give metallic copper and SO2. This blister copper is cast into molds. The ingots, and sometimes directly the molten crude copper, are subjected to fire refining to recover the valuable associated elements (Au, Ag, Se, Fe, Bi) and to remove the harmful impurities. This process is based on the greater affinity (than that of copper) of the impurity metals for oxygen: Fe, Zn, Co, some of the Ni, and other metals go into the slag as oxides, whereas sulfur as SO2 is removed with the gases. After removal of the slag, the copper is “poled” to reduce the dissolved Cu2O, a process in which the ends of green birch or pine logs are immersed into the liquid metal. The copper is then poured into flat molds.

For purposes of electrolytic refining, the resulting ingots are suspended in a bath containing a CuSO4 solution, which is acidified with H2SO4. The ingots serve as the anodes. On passing an electric current, the anodes dissolve and pure copper is deposited on the cathodes, which are thin copper sheets also produced by electrolysis in special matrix baths. Surface-active additives (joiner’s glue, thiourea) are added to the electrolyte in order to obtain thick and fine-grained deposits. The resulting cathode copper is rinsed with water and remelted. The noble metals, Se, Te, and other valuable materials associated with copper are concentrated in the anode slime, from which they are extracted by special processing. Nickel is concentrated in the electrolyte; removal of some of the solution for evaporation and crystallization makes it possible to obtain nickel in the form of nickel sulfate.

Hydrometallurgical methods are also used to obtain copper, predominantly from poorly oxidized and native ores. These methods are based on the selective solution of copper-containing minerals, usually in weak H2SO4 or ammonia solutions. Copper is either precipitated out of solution with iron or separated by electrolysis on insoluble anodes. Extremely promising methods applicable to mixed ores are combined hydroflotation methods, in which the oxygen compounds of copper are dissolved in sulfuric acid solutions and the sulfides are separated by flotation. Autoclave hydrometallurgical processes, at high temperatures and pressures, are being increasingly used.

Uses. The great importance of copper in technology is due to copper’s various valuable properties, including high electrical conductivity, ductility, and heat conductivity. Owing to these properties, copper is the principal material from which electrical conducting wires and cables are made. More than 50 percent of copper production is used by electrical industries. All impurities lower the electrical conductivity of copper and therefore the highest purity metal (not less than 99.9 percent pure) is used in electrical technology. High heat conductivity and corrosion resistance make it possible to manufacture important parts for heat exchangers, refrigerators, vacuum devices, and other equipment from copper. About 30 to 40 percent of the copper is used to form various alloys, of which the brasses (from 0 to 50 percent Zn) and the bronzes (tin-, aluminum-, lead-, beryllium-) are the most important. In addition to use by heavy industry and the communications and transportation industries, copper, mainly in the form of salts, is used in the production of mineral pigments and of substances for the control of plant pests and diseases and as a microingredient of fertilizers and a catalyst for oxidation processes. It is also used in the leather and fur industries and in the production of rayon.


Copper in art. Copper has been used since the Bronze Age (ornaments, sculpture, and household utensils and vessels). Forged and cast articles from copper and its alloys are decorated by embossing, engraving, and stamping. The ease of working with copper, owing to the metal’s softness, makes it possible for artists to achieve a variety of textures, careful shaping of details, and fine modeling. Articles made from copper are distinguished by the beauty of the golden or reddish tones, as well as by the shine acquired by polishing. Copper is frequently gold-plated, covered with patina, toned, and decorated with enamel. Since the 15th century, it has also been used for the production of engraving plates.

Copper in the organism. Copper is a trace element necessary to plants and animals. The principal biochemical function of copper is its participation in enzymatic reactions as activator or as a component of copper-containing enzymes. The quantity of copper in plants varies from 0.0001 to 0.05 percent (dry weight) and depends on the plant species and on the copper content of the soil. Copper is a constituent of the enzymes oxidases and of the protein plastocyanin in plants. In optimum concentrations, copper increases the resistance of plants to cold and promotes growth and development. Among animals, some invertebrates contain large amounts of copper (mollusks and crustaceans contain 0.15-0.26 percent copper in the hemocyanin). Ingested with food, copper is absorbed in the intestines, combines with the protein in the blood serum—albumin—and is then absorbed by the liver, from which it returns to the blood as a component of the protein ceruloplasmin and is then transported to the organs and tissues.

The copper content in man varies (per 100 g of dry weight) from 5 mg in the liver to 0.7 mg in bones. In body fluids, the copper content varies from 100 μg (per 100 ml) in the blood to 10 μg in the cerebraspinal fluid. The adult organism contains a total of 100 mg of copper. Copper is a component of a number of enzymes (for example, tyrosinase and cytochrome oxidase) and stimulates the blood-forming function of the bone marrow. Small doses of copper, for example, affect carbohydrate metabolism by lowering the blood sugar level and the metabolism of mineral substances by lowering the phosphorus content in the blood. Increased content of copper in the blood leads to the transformation of the mineral compounds of iron into organic compounds and stimulates the utilization of the iron stored in the liver in the synthesis of hemoglobin.

In the case of copper deficiency, the cereals develop the processing disease, and the fruit plants develop exanthematous diseases. Copper deficiency in animals leads to decreased absorption and utilization of iron, which in turn leads to anemia accompanied by diarrhea and cachexia. Copper-containing microfertilizers are used, and copper feed supplements in the form of copper salts are used for animals. Copper poisoning leads to anemia, diseases of the liver, and Wilson’s disease. In humans, copper poisoning occurs rarely owing to the refined mechanisms of copper absorption and elimination. However, large doses of copper lead to vomiting; absorption of copper may lead to general poisoning (diarrhea, weakening of the respiration and heart activity, asphyxia, comatose state).


Medicine. In medicine, copper sulfate is used as an antiseptic and binder in the form of eye drops for the treatment of conjunctivitis and trachoma. Copper sulfate solutions are also used for the treatment of skin burns caused by phosphorus. Sometimes copper sulfate is used as an emetic. Copper nitrate is used in the form of an eye ointment for trachoma and conjunctivitis.


Smirnov, V. I. Metallurgiia medi i nikelia. Sverdlovsk-Moscow, 1950.
Avetisian, Kh. K. Metallurgiia chernovoi medi. Moscow, 1954.
Gazarian, L. M. Pirometallurgiia medi. Moscow, 1960.
Spravochnik metallurgapo tsvetnym metallam, 2nd ed. Vol. 1, Moscow, 1953; vol. 2, Moscow, 1947. Edited by N. N. Murach.
Levinson, N. R. [“Izdeliia iz tsvetnogo i chernogo metalla.”] In Russkoe dekorativnoe iskusstvo, vols. 1-3. Moscow, 1962-65.
Hadaway, W. S. Illustrations of Metal Work in Brass and Copper Mostly South Indian. Madras, 1913.
Wainwright, G. A. “The Occurrence of Tin and Copper Near Byblos.” Journal of Egyptian Archaeology, 1934, vol. 20, part 1, pp. 29-32.
Bergsøe, P. The Gilding Process and the Metallurgy of Copper and Lead Among the Pre-Columbian Indians. Copenhagen, 1938
Frieden, E. “Rol’ soedinenii medi v prirode.” In Gorizonty biokhimii. Moscow, 1964. (Translated from English.)
Frieden, E. “Biokhimiia medi.” In Molekuly i kletki, fasc. 4. Moscow, 1969. (Translated from English.)
Frieden, E. Biologicheskaia rol’ medi. Moscow, 1970. (Translated from English.)
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A chemical element, symbol Cu, atomic number 29, atomic weight 63.546.
One of the most important nonferrous metals; a ductile and malleable metal found in various ores and used in industry, engineering, and the arts in both pure and alloyed form.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


A lustrous reddish metal, highly ductile and malleable; has high tensile strength, is an excellent electrical and thermal conductor, is available in a wide variety of shapes; widely used for downspouts, electrical conductors, flashing, gutters, roofing, etc.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


Indian talisman to prevent cholera. [Ind. Myth.: Jobes, 369]
See: Healing
Allusions—Cultural, Literary, Biblical, and Historical: A Thematic Dictionary. Copyright 2008 The Gale Group, Inc. All rights reserved.


a. a malleable ductile reddish metallic element 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. Symbol: Cu; atomic no.: 29; atomic wt.: 63.546; valency: 1 or 2; relative density: 8.96; melting pt.: 1084.87±+0.2°C; boiling pt.: 2563°C
b. (as modifier): a copper coin
a. the reddish-brown colour of copper
b. (as adjective): copper hair
3. Informal any copper or bronze coin
4. any of various small widely distributed butterflies of the genera Lycaena, Heodes, etc., typically having reddish-brown wings: family Lycaenidae
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005


Conventional electrical network cable with a core conductor of copper (or aluminium!)

Opposed to light pipe or, say, a short-range microwave link.
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(Cu) A reddish-brown metal that is highly conductive and widely used for electrical wire. When a signal "runs over copper," it means that a metal wire is used rather than a glass wire (optical fiber). See copper chip.
Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
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