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95-520: The Western Pacific line was completed through the Feather River Canyon in 1909. The IV was incorporated on June 30, 1916 and grading commenced a month later. The laying of 56 and 65 pound rails commenced in November 1916. On September 1, 1917 the 21.6 mile line was completed at a cost of $ 746,483. The IV was constructed during a copper boom that ran from 1915-1930 in the area. At the north end of

190-573: A Gilman reagent . These can undergo substitution with alkyl halides to form 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 . Conjugate addition to enones and carbocupration of alkynes can also be achieved with organocopper compounds. Copper(I) forms

285-593: A Vinča culture site in Pločnik ( Serbia ), and believed to have been smelted from a natural tin-copper ore, stannite . Other early examples date to the late 4th millennium BC in Egypt , Susa (Iran) and some ancient sites in China, Luristan (Iran), Tepe Sialk (Iran), Mundigak (Afghanistan), and Mesopotamia (Iraq). Tin bronze was superior to arsenic bronze in that the alloying process could be more easily controlled, and

380-696: A covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper. At the macroscopic scale, introduction of extended defects to the crystal lattice , such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is usually supplied in a fine-grained polycrystalline form, which has greater strength than monocrystalline forms. The softness of copper partly explains its high electrical conductivity ( 59.6 × 10   S /m ) and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature. This

475-636: 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 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,

570-425: A spin of 3 ⁄ 2 . The other isotopes are radioactive , with the most stable being Cu with a half-life of 61.83 hours. Seven metastable isomers have been characterized; Cu is the longest-lived with a half-life of 3.8 minutes. Isotopes with a mass number above 64 decay by β , whereas those with a mass number below 64 decay by β . Cu , which has

665-399: A blast furnace. A potential source of copper is polymetallic nodules, which have an estimated concentration 1.3%. Like 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

760-459: A blue crystalline penta hydrate , the most familiar copper compound in the laboratory. It is used in a fungicide 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

855-518: A copper oxide (eventually becoming copper carbonate) layer is formed, the underlying metal is protected from further corrosion . This can be seen on statues from the Hellenistic period. If copper chlorides are formed, a corrosion-mode called " bronze disease " will eventually completely destroy it. Bronze, or bronze-like alloys and mixtures, were used for coins over a longer period. Bronze was especially suitable for use in boat and ship fittings prior to

950-457: A green patina of compounds called verdigris . Copper is sometimes used in decorative art , both in its elemental metal form and in compounds as pigments. Copper compounds are used as bacteriostatic agents , fungicides , and wood preservatives . Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase . In molluscs and crustaceans , copper

1045-495: A half-life of 12.7 hours, decays both ways. Cu and Cu have significant applications. Cu is used in Cu Cu-PTSM as a radioactive tracer for positron emission tomography . 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

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1140-683: A layer of brown-black copper oxide which, unlike the rust that forms on iron in moist air, protects the underlying metal from further corrosion ( passivation ). A green layer of verdigris (copper carbonate) can often be seen on old copper structures, such as the roofing of many older buildings and the Statue of Liberty . Copper tarnishes when exposed to some sulfur compounds, with which it reacts to form various copper sulfides . There are 29 isotopes of copper. Cu and Cu are stable, with Cu comprising approximately 69% of naturally occurring copper; both have

1235-655: A major influence on the development of cultures. In Europe, a major source of tin was the British deposits of ore in Cornwall , which were traded as far as Phoenicia in the eastern Mediterranean . In many parts of the world, large hoards of bronze artifacts are found, suggesting that bronze also represented a store of value and an indicator of social status. In Europe, large hoards of bronze tools, typically socketed axes (illustrated above), are found, which mostly show no signs of wear. With Chinese ritual bronzes , which are documented in

1330-532: A natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air. This is due to the low plasma frequency of the metal, which lies in the red part of the visible spectrum, causing it to absorb the higher-frequency green and blue colors. As with other metals, if copper is put in contact with another metal in the presence of an electrolyte , galvanic corrosion will occur. Copper does not react with water, but it does slowly react with atmospheric oxygen to form

1425-407: A red-brown precipitate with copper(II) salts. 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 many uses in chemistry . They are synthesized by treating copper(I) compounds with Grignard reagents , terminal alkynes or organolithium reagents ; in particular, the last reaction described produces

1520-451: A rich variety of compounds, usually with oxidation states +1 and +2, which are often called cuprous and cupric , respectively. Copper compounds promote or catalyse numerous chemical and biological processes. 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 halides . Both cuprous and cupric oxides are known. Among

1615-546: A sharper edge longer. Bronze was still used during the Iron Age, and has continued in use for many purposes to the modern day. There are many different bronze alloys, but typically modern bronze is 88% copper and 12% tin. Alpha bronze consists of the alpha solid solution of tin in copper. Alpha bronze alloys of 4–5% tin are used to make coins, springs, turbines and blades. Historical "bronzes" are highly variable in composition, as most metalworkers probably used whatever scrap

1710-424: A variety of minerals, including native copper , copper sulfides such as chalcopyrite , bornite , digenite , covellite , and chalcocite , copper sulfosalts such as tetrahedite-tennantite , and enargite , copper carbonates such as azurite and malachite , and as copper(I) or copper(II) oxides such as cuprite and tenorite , respectively. The largest mass of elemental copper discovered weighed 420 tonnes and

1805-436: A variety of weak complexes with alkenes and carbon monoxide , especially in the presence of amine ligands. Copper(III) is most often found in oxides. A simple example is potassium cuprate , KCuO 2 , a blue-black solid. The most extensively studied copper(III) compounds are the cuprate superconductors . Yttrium barium copper oxide (YBa 2 Cu 3 O 7 ) consists of both Cu(II) and Cu(III) centres. Like oxide, fluoride

1900-416: Is a better conductor of heat and electricity than most steels. The cost of copper-base alloys is generally higher than that of steels but lower than that of nickel -base alloys. Bronzes are typically ductile alloys, considerably less brittle than cast iron. Copper and its alloys have a huge variety of uses that reflect their versatile physical, mechanical, and chemical properties . Some common examples are

1995-579: Is a constituent of the blood pigment hemocyanin , replaced by the iron-complexed hemoglobin in fish and other vertebrates . 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. In the Roman era , copper was mined principally on Cyprus , the origin of the name of the metal, from aes cyprium (metal of Cyprus), later corrupted to cuprum (Latin). Coper ( Old English ) and copper were derived from this,

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2090-405: Is a highly basic anion and is known to stabilize metal ions in high oxidation states. Both copper(III) and even copper(IV) fluorides are known, K 3 CuF 6 and Cs 2 CuF 6 , respectively. Some copper proteins form oxo complexes , which, in extensively studied synthetic analog systems, feature copper(III). With tetrapeptides , purple-colored copper(III) complexes are stabilized by

2185-401: 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 possible current density of copper in open air is approximately 3.1 × 10  A/m , above which it begins to heat excessively. Copper is one of a few metallic elements with

2280-418: Is in modern times. Because historical artworks were often made of brasses (copper and zinc) and bronzes of different metallic compositions, modern museum and scholarly descriptions of older artworks increasingly use the generalized term "copper alloy" instead of the names of individual alloys. This is done (at least in part) to prevent database searches from failing merely because of errors or disagreements in

2375-513: Is likely that 'nehoshet' refers to copper and its alloys with tin, now called bronze. In the King James Version, there is no use of the word 'bronze' and 'nehoshet' was translated as 'brass'. Modern translations use 'bronze'. Bronze (nehoshet) was used widely in the Tabernacle for items such as the bronze altar (Exodus Ch.27), bronze laver (Exodus Ch.30), utensils, and mirror (Exodus Ch.38). It

2470-529: Is melted in a furnace and then reduced and cast into billets and ingots ; lower-purity scrap is refined by electroplating in a bath of sulfuric acid . The environmental cost of copper mining was estimated at 3.7 kg CO2eq per kg of copper in 2019. Codelco, a major producer in Chile, reported that in 2020 the company emitted 2.8t CO2eq per ton (2.8 kg CO2eq per kg) of fine copper. Greenhouse gas emissions primarily arise from electricity consumed by

2565-444: Is one of the most important constituents of silver and karat 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 , called cupronickel , is used in low-denomination coins, often for the outer cladding. The US five-cent coin (currently called

2660-437: Is recovered from mine tailings and heaps. A variety of methods are used including leaching with sulfuric acid, ammonia, ferric chloride. Biological methods are also used. A significant source of copper is from recycling. Recycling is facilitated because copper is usually deployed in its metallic state. In 2001, a typical automobile contained 20–30 kg of copper. Recycling usually begins with some melting process using

2755-536: Is used as a conductor of heat and electricity, as a building material , and as a constituent of various metal alloys , such as sterling silver used in jewelry , cupronickel used to make marine hardware and coins , and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable metallic form ( native metals ). This led to very early human use in several regions, from c.  8000 BC . Thousands of years later, it

2850-411: 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 is a Japanese decorative alloy of copper containing a low percentage of gold, typically 4–10%, that can be patinated to a dark blue or black color. Copper forms

2945-453: Is used to make hammers , mallets , wrenches and other durable tools to be used in explosive atmospheres or in the presence of flammable vapors. Bronze is used to make bronze wool for woodworking applications where steel wool would discolor oak . Phosphor bronze is used for ships' propellers, musical instruments, and electrical contacts. Bearings are often made of bronze for its friction properties. It can be impregnated with oil to make

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3040-541: Is used to make the tone rings of many professional model banjos . The tone ring is a heavy (usually 3 lb; 1.4 kg) folded or arched metal ring attached to a thick wood rim, over which a skin, or most often, a plastic membrane (or head) is stretched – it is the bell bronze that gives the banjo a crisp powerful lower register and clear bell-like treble register. Bronze has also been used in coins; most "copper" coins are actually bronze, with about 4 percent tin and 1 percent zinc. As with coins, bronze has been used in

3135-675: The British Geological Survey , in 2005, Chile was the top producer of copper with at least one-third of the world share followed by the United States, Indonesia and Peru. Copper can also be recovered through the in-situ leach process. Several sites in the state of Arizona are considered prime candidates for this method. 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 currently being researched are polymetallic nodules , which are located at

3230-606: The Denver and Rio Grande Railroad . The locomotives (D&RG #661 and #668) were sold to IV in December 1916. The locomotives served the IV until the railroad ceased operations and were scrapped in December 1939. The railroad also had a passenger car and two freight cars. While the IV was built primarily to serve the copper mine at Engels, it was also a common carrier. Alvin Fickewirth states that

3325-547: The Etruscans were making bronze mirrors in the sixth century BC, and Greek and Roman mirrors followed the same pattern. Although other materials such as speculum metal had come into use, and Western glass mirrors had largely taken over, bronze mirrors were still being made in Japan and elsewhere in the eighteenth century, and are still made on a small scale in Kerala , India. Bronze is

3420-555: The Golden Age , when men lived among the gods; the Silver age , where youth lasted a hundred years; and the Bronze Age , the era of heroes. It was first adopted for a sports event at the 1904 Summer Olympics . At the 1896 event, silver was awarded to winners and bronze to runners-up, while at 1900 other prizes were given rather than medals. Bronze is the normal material for the related form of

3515-588: The Great Lakes may have also been mining copper during this time, making it one of the oldest known examples of copper extraction in the world. There is evidence from prehistoric lead pollution from lakes in Michigan that people in the region began mining copper c.  6000 BC . Evidence suggests that utilitarian copper objects fell increasingly out of use in the Old Copper Complex of North America during

3610-536: The International Resource Panel '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

3705-743: The Kingdom of Benin ; in Europe, Grecian bronzes typically of figures from Greek mythology ; in east Asia , Chinese ritual bronzes of the Shang and Zhou dynasty —more often ceremonial vessels but including some figurine examples. Bronze continues into modern times as one of the materials of choice for monumental statuary. Tiffany Glass Studios, made famous by Louis C. Tiffany commonly referred to his product as favrile glass or " Tiffany glass ," and used bronze in their artisan work for his Tiffany lamps . The largest and most ornate bronze fountain known to be cast in

3800-699: 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

3895-521: The Vinča culture date to 4500 BC. Sumerian and Egyptian artifacts of copper and bronze alloys date to 3000 BC. Egyptian Blue , or cuprorivaite (calcium copper silicate) is a synthetic pigment that contains copper and started being used in ancient Egypt around 3250 BC. The manufacturing process of Egyptian blue was known to the Romans, but by the fourth century AD the pigment fell out of use and

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3990-539: The plaquette , normally a rectangular work of art with a scene in relief , for a collectors' market. Bronze is also associated with eighth wedding anniversaries. There are over 125 references to bronze ('nehoshet'), which appears to be the Hebrew word used for copper and any of its alloys. However, the Old Testament era Hebrews are not thought to have had the capability to manufacture zinc (needed to make brass) and so it

4085-623: The 12th-century Romanesque Baptismal font at St Bartholomew's Church, Liège is sometimes described as bronze and sometimes as brass . In the Bronze Age, two forms of bronze were commonly used: "classic bronze", about 10% tin, was used in casting; and "mild bronze", about 6% tin, was hammered from ingots to make sheets. Bladed weapons were mostly cast from classic bronze, while helmets and armor were hammered from mild bronze. Modern commercial bronze (90% copper and 10% zinc) and architectural bronze (57% copper, 3% lead , 40% zinc) are more properly regarded as brass alloys because they contain zinc as

4180-638: The 1920s when it reached a population of 1,200 people. In 1930 the Engels mine was closed due to the declining value of copper. However, the IV continued to operate to serve the town and residents until 1938, when the railroad and town were dismantled. The houses were moved to Greenville, Quincy and Portola and the last cabin was removed in the 1960s. The standard gauge railroad had two locomotives, #1 and #2. The 2-8-0 (consolidation type) locomotives were built in 1891 & 1892 by Baldwin Locomotive Works for

4275-539: The 9th or 10th century AD. Carbon dating has established mining at 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 likely led to

4370-512: The Bronze Age and a shift towards an increased production of ornamental copper objects occurred. 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. 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

4465-577: The IV was sold to the Western Pacific Railroad (WP) in 1921. A 1931 public timetable published by WP listed the Indian Valley Railroad with two daily round trip trains. However, Donald B. Robertson's book states that the owner of the IV in 1931 was "California-Engels Mining Company". The railroad ceased operations as a common carrier on December 5, 1938. The line was scrapped and removed within two years. The old railroad right of way

4560-482: The IV, copper ore was hauled over road to Keddie where the ore was loaded into Western Pacific Railroad freight cars and transported to a smelter at Garfield, Utah. When the IV opened in 1917, it began hauling passengers and copper ore daily from Lower Camp to the Western Pacific station at Paxton. A year later, the townsite of Engelmine, or Engel, was laid out and gridded near Lower Camp. The townsite peaked in

4655-535: 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 working of native copper, then annealing , smelting , and, finally, lost-wax casting . In southeastern Anatolia , all four of these techniques appear more or less simultaneously at

4750-603: The Plumas Copper Belt was the Engels mine. The Engels mine was named after Henry A. Engels, who settled the area in the 1880s and began to mine copper . In 1901 the Engels Copper Mining Company was founded. In 1911 the company built a smelter at China Gulch but was soon prohibited by the U.S. Forest Service which had stewardship over the land that was within the Plumas National Forest . Prior to

4845-597: The Roman Empire. Bronze Bronze is an alloy consisting primarily of copper , commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium , manganese , nickel , or zinc ) and sometimes non-metals, such as phosphorus , or metalloids , such as arsenic or silicon . These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as strength , ductility , or machinability . The archaeological period in which bronze

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4940-521: The affected areas is highly acidic, with a pH range of 2.1–4.9, and shows elevated electrical conductivity levels between 280 and 1561 mS/cm. These changes in water chemistry make the environment inhospitable for fish, essentially rendering the water uninhabitable for aquatic life. Numerous copper alloys have been formulated, many with important uses. Brass is an alloy of copper and zinc . Bronze usually refers to copper- tin alloys, but can refer to any alloy of copper such as aluminium bronze . Copper

5035-531: The atmosphere; 150 mg/kg in soil; 30 mg/kg in vegetation; 2 μg/L in freshwater and 0.5 μg/L in seawater. Most copper is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0% copper. Sites include Chuquicamata , in Chile, Bingham Canyon Mine , in Utah, United States, and El Chino Mine , in New Mexico, United States. According to

5130-452: The barrel. It is still widely used today for springs, bearings, bushings, automobile transmission pilot bearings, and similar fittings, and is particularly common in the bearings of small electric motors . Phosphor bronze is particularly suited to precision-grade bearings and springs. It is also used in guitar and piano strings. Unlike steel, bronze struck against a hard surface will not generate sparks, so it (along with beryllium copper )

5225-686: The beginning of the Neolithic c.  7500 BC . Copper smelting was independently invented in different places. The earliest evidence of lost-wax casting copper comes from an amulet found in Mehrgarh , Pakistan, and is dated to 4000 BC. Investment casting was invented in 4500–4000 BC in Southeast Asia Smelting was probably discovered in China before 2800 BC, in Central America around 600 AD, and in West Africa about

5320-527: The company, especially when sourced from fossil fuels, and from engines required for copper extraction and refinement. Companies that mine land often mismanage waste, rendering the area sterile for life. Additionally, nearby rivers and forests are also negatively impacted. The Philippines is an example of a region where land is overexploited by mining companies. Copper mining waste in Valea Şesei, Romania, has significantly altered nearby water properties. The water in

5415-522: 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 . A timeline of copper illustrates how this metal has advanced human civilization for the past 11,000 years. Copper occurs naturally as native metallic copper and was known to some of the oldest civilizations on record. The history of copper use dates to 9000 BC in

5510-454: The depths of the Pacific Ocean approximately 3000–6500 meters below sea level. These nodules contain other valuable metals such as cobalt and nickel . Copper has been in use for at least 10,000 years, but more than 95% of all copper ever mined and smelted has been extracted since 1900. As with many natural resources, the total amount of copper on Earth is vast, with around 10 tons in

5605-550: The discovery of iron smelting . Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6500 and 3000 BC. A copper spearpoint found in Wisconsin has been dated to 6500 BC. Copper usage by the indigenous peoples of the Old Copper Complex from the Great Lakes region of North America has been radiometrically dated to as far back as 7500 BC. Indigenous peoples of North America around

5700-545: 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: Aqueous ammonia results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, forming tetraamminecopper(II) : Many other oxyanions form complexes; these include copper(II) acetate , copper(II) nitrate , and copper(II) carbonate . Copper(II) sulfate forms

5795-545: The high electrical conductivity of pure copper, low-friction properties of bearing bronze (bronze that has a high lead content— 6–8%), resonant qualities of bell bronze (20% tin, 80% copper), and resistance to corrosion by seawater of several bronze alloys. The melting point of bronze varies depending on the ratio of the alloy components and is about 950 °C (1,742 °F). Bronze is usually nonmagnetic, but certain alloys containing iron or nickel may have magnetic properties. Typically bronze oxidizes only superficially; once

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5890-681: The highest form of sculpture in Ancient Greek art , though survivals are few, as bronze was a valuable material in short supply in the Late Antique and medieval periods. Many of the most famous Greek bronze sculptures are known through Roman copies in marble, which were more likely to survive. In India, bronze sculptures from the Kushana ( Chausa hoard ) and Gupta periods ( Brahma from Mirpur-Khas , Akota Hoard, Sultanganj Buddha ) and later periods ( Hansi Hoard) have been found. Indian Hindu artisans from

5985-479: The inscriptions they carry and from other sources, the case is clear. These were made in enormous quantities for elite burials, and also used by the living for ritual offerings. Though bronze is generally harder than wrought iron , with Vickers hardness of 60–258 vs. 30–80, the Bronze Age gave way to the Iron Age after a serious disruption of the tin trade: the population migrations of around 1200–1100 BC reduced

6080-511: The later spelling first used around 1530. Copper, silver , and 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 and are characterized by high ductility , and electrical and thermal conductivity. The filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through metallic bonds . Unlike metals with incomplete d-shells, metallic bonds in copper are lacking

6175-419: The level of <1% Cu. Concentration of the ore is required, which begins with comminution followed by froth flotation . The remaining concentrate is the smelted, which can be described with two simplified equations: Cuprous oxide reacts with cuprous sulfide to convert to blister copper upon heating This roasting gives matte copper, roughly 50% Cu by weight, which is purified by electrolysis. Depending on

6270-824: The main alloying ingredient. They are commonly used in architectural applications. Plastic bronze contains a significant quantity of lead, which makes for improved plasticity, and was possibly used by the ancient Greeks in ship construction. Silicon bronze has a composition of Si: 2.80–3.80%, Mn: 0.50–1.30%, Fe: 0.80% max., Zn: 1.50% max., Pb: 0.05% max., Cu: balance. Other bronze alloys include aluminium bronze , phosphor bronze , manganese bronze, bell metal , arsenical bronze , speculum metal , bismuth bronze , and cymbal alloys . Copper-based alloys have lower melting points than steel or iron and are more readily produced from their constituent metals. They are generally about 10 percent denser than steel, although alloys using aluminum or silicon may be slightly less dense. Bronze

6365-458: The manufacture of various types of medals for centuries, and " bronze medals " are known in contemporary times for being awarded for third place in sporting competitions and other events. The term is now often used for third place even when no actual bronze medal is awarded. The usage in part arose from the trio of gold , silver and bronze to represent the first three Ages of Man in Greek mythology:

6460-643: The massive bronze doors to the United States Supreme Court Building in Washington, DC. Before it became possible to produce glass with acceptably flat surfaces, bronze was a standard material for mirrors. Bronze was used for this purpose in many parts of the world, probably based on independent discoveries. Bronze mirrors survive from the Egyptian Middle Kingdom (2040–1750 BC), and China from at least c.  550 BC . In Europe,

6555-472: The modern world. The price of copper is volatile . After a peak in 2022 the price unexpectedly fell. The global market for copper is one of the most commodified and financialized of the commodity markets , and has been so for decades. The great majority of copper ores are sulfides. Common ores are the sulfides chalcopyrite (CuFeS 2 ), bornite (Cu 5 FeS 4 ) and, to a lesser extent, covellite (CuS) and chalcocite (Cu 2 S). These ores occur at

6650-643: The naming of historic copper alloys. The word bronze (1730–1740) is borrowed from Middle French bronze (1511), itself borrowed from Italian bronzo ' bell metal, brass ' (13th century, transcribed in Medieval Latin as bronzium ) from either: The discovery of bronze enabled people to create metal objects that were harder and more durable than previously possible. Bronze tools , weapons , armor , and building materials such as decorative tiles were harder and more durable than their stone and copper (" Chalcolithic ") predecessors. Initially, bronze

6745-516: The numerous copper sulfides , important examples include copper(I) sulfide ( Cu 2 S ) and copper monosulfide ( CuS ). Cuprous halides with fluorine , chlorine , bromine , and iodine are known, as are cupric halides with fluorine , chlorine , and bromine . Attempts to prepare copper(II) iodide yield only copper(I) iodide and iodine. Copper forms coordination complexes with ligands . In aqueous solution, copper(II) exists as [Cu(H 2 O) 6 ] . This complex exhibits

6840-428: The ore, sometimes other metals are obtained during the electrolysis including platinum and gold. Aside from sulfides, another family of ores are oxides. Approximately 15% of the world's copper supply derives from these oxides. The beneficiation process for oxides involves extraction with sulfuric acid solutions followed by electrolysis. In parallel with the above method for "concentrated" sulfide and oxide ores, copper

6935-567: The period of the Chola empire in Tamil Nadu used bronze to create intricate statues via the lost-wax casting method with ornate detailing depicting the deities of Hinduism . The art form survives to this day, with many silpis, craftsmen, working in the areas of Swamimalai and Chennai . In antiquity other cultures also produced works of high art using bronze. For example: in Africa, the bronze heads of

7030-424: The preferred metal for bells in the form of a high tin bronze alloy known as bell metal , which is typically about 23% tin. Nearly all professional cymbals are made from bronze, which gives a desirable balance of durability and timbre . Several types of bronze are used, commonly B20 bronze , which is roughly 20% tin, 80% copper, with traces of silver, or the tougher B8 bronze made from 8% tin and 92% copper. As

7125-452: The proprietary Oilite and similar material for bearings. Aluminum bronze is hard and wear-resistant, and is used for bearings and machine tool ways. The Doehler Die Casting Co. of Toledo, Ohio were known for the production of Brastil , a high tensile corrosion resistant bronze alloy. The Seagram Building on New York City 's Park Avenue is the "iconic glass box sheathed in bronze, designed by Mies van der Rohe ." The Seagram Building

7220-454: The ready availability of silicon bronze brazing rod, which allows color-matched repair of defects in castings. Aluminum is also used for the structural metal aluminum bronze. Bronze parts are tough and typically used for bearings , clips, electrical connectors and springs . Bronze also has low friction against dissimilar metals, making it important for cannons prior to modern tolerancing , where iron cannonballs would otherwise stick in

7315-674: The resulting alloy was stronger and easier to cast. Also, unlike those of arsenic , metallic tin and the fumes from tin refining are not toxic . Tin became the major non-copper ingredient of bronze in the late 3rd millennium BC. Ores of copper and the far rarer tin are not often found together (exceptions include Cornwall in the United Kingdom, one ancient site in Thailand and one in Iran), so serious bronze work has always involved trade with other regions. Tin sources and trade in ancient times had

7410-664: The secret to its manufacturing process became lost. The Romans said the blue pigment was made from copper, silica, lime and natron and was known to them as caeruleum . 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

7505-471: The shipping of tin around the Mediterranean and from Britain, limiting supplies and raising prices. As the art of working in iron improved, iron became cheaper and improved in quality. As later cultures advanced from hand- wrought iron to machine- forged iron (typically made with trip hammers powered by water), blacksmiths also learned how to make steel . Steel is stronger and harder than bronze and holds

7600-438: 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 such as cystine form very stable chelate complexes with copper(II) including in the form of metal-organic biohybrids (MOBs). Many wet-chemical tests for copper ions exist, one involving potassium ferricyanide , which gives

7695-469: The tin content in a bell or cymbal rises, the timbre drops. Bronze is also used for the windings of steel and nylon strings of various stringed instruments such as the double bass , piano, harpsichord , and guitar. Bronze strings are commonly reserved on pianoforte for the lower pitch tones, as they possess a superior sustain quality to that of high-tensile steel. Bronzes of various metallurgical properties are widely used in struck idiophones around

7790-399: 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

7885-439: The unusual and desirable property of expanding slightly just before they set, thus filling the finest details of a mould. Then, as the bronze cools, it shrinks a little, making it easier to separate from the mould. The Assyrian king Sennacherib (704–681 BC) claims to have been the first to cast monumental bronze statues (of up to 30 tonnes) using two-part moulds instead of the lost-wax method . Bronze statues were regarded as

7980-419: The wide employment of stainless steel owing to its combination of toughness and resistance to salt water corrosion. Bronze is still commonly used in ship propellers and submerged bearings. In the 20th century, silicon was introduced as the primary alloying element, creating an alloy with wide application in industry and the major form used in contemporary statuary . Sculptors may prefer silicon bronze because of

8075-637: The world was by the Roman Bronze Works and General Bronze Corporation in 1952. The material used for the fountain, known as statuary bronze, is a quaternary alloy made of copper, zinc, tin, and lead, and traditionally golden brown in color. This was made for the Andrew W. Mellon Memorial Fountain in Federal Triangle in Washington, DC. Another example of the massive, ornate design projects of bronze, and attributed to General Bronze/Roman Bronze Works were

8170-705: The world, notably bells, singing bowls, gongs , cymbals, and other idiophones from Asia. Examples include Tibetan singing bowls , temple bells of many sizes and shapes, Javanese gamelan , and other bronze musical instruments . The earliest bronze archeological finds in Indonesia date from 1–2 BC, including flat plates probably suspended and struck by a wooden or bone mallet. Ancient bronze drums from Thailand and Vietnam date back 2,000 years. Bronze bells from Thailand and Cambodia date back to 3600 BC. Some companies are now making saxophones from phosphor bronze (3.5 to 10% tin and up to 1% phosphorus content). Bell bronze/B20

8265-515: Was found in 1857 on the Keweenaw Peninsula in Michigan, US. Native copper is a polycrystal , with the largest single crystal ever described measuring 4.4 × 3.2 × 3.2 cm . Copper is the 26th most abundant element in Earth's crust , representing 50 ppm compared with 75 ppm for zinc , and 14 ppm for lead . Typical background concentrations of copper do not exceed 1 ng/m in

8360-520: Was made out of copper and arsenic or from naturally or artificially mixed ores of those metals, forming arsenic bronze . The earliest known arsenic-copper-alloy artifacts come from a Yahya Culture (Period V 3800-3400 BCE) site, at Tal-i-Iblis on the Iranian plateau , and were smelted from native arsenical copper and copper-arsenides, such as algodonite and domeykite . The earliest tin-copper-alloy artifact has been dated to c.  4650 BC , in

8455-468: Was mentioned in the account of Moses holding up a bronze snake on a pole in Numbers Ch.21. In First Kings, it is mentioned that Hiram was very skilled in working with bronze, and he made many furnishings for Solomon's Temple including pillars, capitals, stands, wheels, bowls, and plates, some of which were highly decorative (see I Kings 7:13-47). Bronze was also widely used as battle armor and helmet, as in

8550-424: Was not only the most expensive building of its time — $ 36 million — but it was the first building in the world with floor-to-ceiling glass walls. Mies van der Rohe achieved the crisp edges that were custom-made with specific detailing by General Bronze and "even the screws that hold in the fixed glass-plate windows were made of brass." Bronze is widely used for casting bronze sculptures . Common bronze alloys have

8645-476: Was on hand; the metal of the 12th-century English Gloucester Candlestick is bronze containing a mixture of copper, zinc, tin, lead, nickel, iron, antimony, arsenic and an unusually large amount of silver – between 22.5% in the base and 5.76% in the pan below the candle. The proportions of this mixture suggest that the candlestick was made from a hoard of old coins. The 13th-century Benin Bronzes are in fact brass, and

8740-405: Was paved over by a road, including portions of State Route 89 and Plumas County Road 213. Copper Copper is a chemical element ; it has symbol Cu (from Latin cuprum ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity . A freshly exposed surface of pure copper has a pinkish-orange color . Copper

8835-547: Was the first metal to be smelted 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 , to create bronze , c.  3500 BC . Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as azurite , malachite , and turquoise , and have been used widely and historically as pigments. Copper used in buildings, usually for roofing, oxidizes to form

8930-587: Was the first time that an entire building was sheathed in bronze. The General Bronze Corporation fabricated 3,200,000 pounds (1,600 tons) of bronze at its plant in Garden City, New York . The Seagram Building is a 38-story, 516-foot bronze-and- topaz -tinted glass building. The building looks like a "squarish 38-story tower clad in a restrained curtain wall of metal and glass." "Bronze was selected because of its color, both before and after aging, its corrosion resistance, and its extrusion properties. In 1958, it

9025-468: Was the hardest metal in widespread use is known as the Bronze Age . The beginning of the Bronze Age in western Eurasia and India is conventionally dated to the mid-4th millennium BC (~3500 BC), and to the early 2nd millennium BC in China; elsewhere it gradually spread across regions. The Bronze Age was followed by the Iron Age starting about 1300 BC and reaching most of Eurasia by about 500 BC, although bronze continued to be much more widely used than it

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