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73-659: The Bronze Horseman (Russian: Медный всадник , literally " copper horseman") is an equestrian statue of Peter the Great in the Senate Square in Saint Petersburg , Russia . It was opened to the public on 7 (18) August 1782 . Commissioned by Catherine the Great , it was created by the French sculptor Étienne Maurice Falconet . The statue influenced a 1833 poem of the same name by Alexander Pushkin , which

146-579: 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

219-696: 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

292-643: 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,

365-561: A rapakivi granite monolith boulder known as the Thunder Stone (Russian: Гром-камень , romanized:  Grom-kamen ) was found at Lakhta , 6 km (3.7 mi) inland from the Gulf of Finland in 1768. The Thunder Stone gained its name from a local legend that thunder split a piece off the stone. Falconet wanted to work on shaping the stone in its original location, but Catherine ordered it be moved before being cut. As it

438-425: 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

511-534: A base, so the finished pedestal weighs considerably less. A 19th-century legend states that while the Bronze Horseman stands in the middle of Saint Petersburg, enemy forces will not be able to conquer the city. During the 900-day Siege of Leningrad by the invading Germans during the Second World War (Leningrad being the city's name from 1924 to 1991), the statue was covered with sandbags and

584-399: 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

657-464: 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

730-459: A friend of his, for the commission. The empress followed his advice and Falconet arrived in Russia in 1766. In 1775 the casting of the statue began, supervised by caster Emelyan Khailov. At one point during the casting, the mould broke, releasing molten bronze that started several fires. All the workers ran except Khailov, who risked his life to salvage the casting. After being remelted and recast,

803-457: 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

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876-505: 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

949-687: 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

1022-532: 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

1095-407: 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

1168-451: 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

1241-511: A short voyage, the stone reached its destination in 1770, after nearly two years of work. A medal was issued to commemorate its arrival, with the legend "Close to Daring". According to the fall 1882 edition of La Nature , the stone's dimensions before being cut were 7 by 14 by 9 metres (23 ft × 46 ft × 30 ft). Based on the density of granite , its weight was determined to be around 1,500 metric tons (1,700 short tons ). Falconet had some of this cut away shaping it into

1314-424: 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

1387-436: 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

1460-411: A wooden shelter. Thus protected, it survived 900 days of bombing and artillery fire, virtually untouched. The Bronze Horseman is the title of a poem written by Aleksandr Pushkin in 1833 , widely considered to be one of the most significant works of Russian literature . Due to the popularity of his work, the statue came to be called the "Bronze Horseman". A major theme of the poem is conflict between

1533-603: 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 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

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1606-583: 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,

1679-405: 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

1752-401: 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

1825-624: Is high in fluoride (1–2 mg/L), making the water naturally fluoridated. Some water companies actually have to remove fluoride from the water. The uranium content of rapakivi is fairly high, up to 24 ppm. Thus, in rapakivi zones, the hazard from radon , a decay product of uranium, is elevated. Some indoor spaces surpass the 400 Bq/m safety limit. Vorma (1976) states that rapakivi granites can be defined as: A more recent definition by Haapala & Rämö states: Rapakivi granites are type-A granites, where at least in larger associated batholites have granites with rapakivi structures. Rapakivi

1898-533: 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

1971-762: 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 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

2044-444: 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

2117-437: 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

2190-518: Is the material used in Åland 's mediaeval stone churches. In 1770, a rapakivi granite monolith boulder, the " Thunder Stone ", was used as the pedestal for the Bronze Horseman statue in Saint Petersburg , Russia. Weighing 1,250 tonnes , this boulder is claimed to be the largest stone ever moved by humans. Modern building uses of rapakivi granites are in polished slabs used for covering buildings, floors, counter tops or pavements. As

2263-411: 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

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2336-403: Is widely considered one of the most significant works of Russian literature . The statue is now one of the symbols of Saint Petersburg. The statue's pedestal is the Thunder Stone , the largest stone ever moved by humans . The stone originally weighed about 1500 tonnes , but was carved down during transportation to its current size and weight of 1,250 tons. The equestrian statue of Peter

2409-702: The Baltic Shield , southern Greenland , southern Africa , India and China . Most of these examples are found within Proterozoic metamorphic belts, although both Archaean and Phanerozoic examples are known. Rapakivi granites have formation ages from Archean to recent and are usually attributed to anorogenic tectonic settings . They have formed in shallow (a few km deep) sills of up to 10 km thickness. Rapakivi granites are often found associated with intrusions of anorthosite , norite , charnockite and mangerite . It has been suggested that

2482-686: 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

2555-607: 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

2628-553: 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

2701-726: 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

2774-525: 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

2847-548: 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

2920-517: 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

2993-760: The Great is situated in the Senate Square (formerly the Decembrists Square), in Saint Petersburg . Catherine the Great , a German princess who married into the Romanov line, was anxious to connect herself to Peter the Great to gain legitimacy in the eyes of the people. She ordered its construction, and had it inscribed with the phrases Petro Primo Catharina Secunda MDCCLXXXII in Latin and Петру перьвому Екатерина вторая, лѣта 1782 ( Petru pervomu Ekaterina vtoraya, lěta 1782 ) in Russian, each meaning 'Catherine

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3066-616: The Great's face on his death mask and numerous portraits she found in Saint Petersburg. The right hand of the statue was modelled from a Roman bronze hand, found in 1771 in Voorburg in the Netherlands at the site of the ancient Roman town Forum Hadriani . On 7 August 1782, fourteen years after excavation of the pedestal began, the finished statue was unveiled in a ceremony with thousands in attendance. Conspicuously absent

3139-541: 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

3212-571: The Roman Empire. Rapakivi granite#Use as a building material Rapakivi was first described by Finnish petrologist Jakob Sederholm in 1891. Since then, southern Finland 's rapakivi granite intrusions have been the type locality of this variety of granite. Rapakivi is a fairly uncommon type of granite, but has been described from localities in North and South America ( Illescas Batholith , Uruguay, Rondônia , Brazil ) parts of

3285-530: The Second to Peter the First, 1782', an expression of her admiration for her predecessor and her view of her own place in the line of great Russian rulers. Having gained her position through a palace coup , Catherine had no legal claim to the throne and wanted to represent herself as Peter's rightful heir. In correspondence with Catherine the Great, Denis Diderot suggested French sculptor Étienne Maurice Falconet ,

3358-521: 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

3431-541: 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

3504-766: 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

3577-531: 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

3650-522: 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

3723-461: 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

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3796-563: 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

3869-400: The discovery of the young man's corpse in a ruined hut floating at the edge of the river. In 1903 the artist Alexandre Benois published an edition of the poem with his illustrations, creating what was considered a masterwork of Art Nouveau . The poem has inspired works in other genres: Reinhold Glière choreographed a ballet based on it, and Nikolai Myaskovsky 's 10th Symphony (1926–7)

3942-552: The effort to oversee their progress. The larger capstan was turned by 32 men, this just barely moving the rock. A further complication was the availability of only 100 m of track, which had to be constantly disassembled and relaid. Nevertheless, the workers made over 150 m of progress a day while on level ground. Upon arrival at the sea an enormous barge was constructed exclusively for the Thunder Stone. The vessel had to be supported on either side by two full-size warships. After

4015-529: The entire suite results from the fractional crystallization of a single parental magma. Rapakivi is enriched in K, Rb, Pb, Nb, Ta, Zr, Hf, Zn, Ga, Sn, Th, U, F and rare earth elements , and poor in Ca, Mg, Al, P and Sr. Fe/Mg, K/Na and Rb/Sr ratios are high. SiO 2 content is 70.5%, which makes rapakivi an acidic granite. Rapakivi is high in fluoride , ranging 0.04–1.53%, compared to other similar rocks at around 0.35%. Consequently, groundwater in rapakivi zones

4088-400: The exact moment of his horse rearing at the edge of a dramatic cliff. His horse can be seen trampling a serpent , variously interpreted to represent treachery, evil, or the enemies of Peter and his reforms. The statue itself is about six metres (20 ft) tall, while the pedestal is another seven metres (23 ft) tall, for a total of approximately 13 metres (43 ft). For the pedestal,

4161-545: 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

4234-404: The first Greek to hold a diploma in engineering. Carburis directed workmen to wait for winter, when the ground was frozen, and then had them drag the large stone over the frozen ground to the sea for shipment and transport to the city. He developed a metallic sled that slid over bronze spheres about 13.5 cm (6 inches) in diameter, over a track. The process worked in a way similar to

4307-494: The later invention of ball bearings . Making the feat even more impressive was that the labour was done entirely by humans; no animals or machines were used in bringing the stone from the original site to the Senate Square. After Carburis devised the method, it took 400 men nine months to move the stone, during which time master stonecutters continuously shaped the enormous granite monolith. Catherine periodically visited

4380-511: 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

4453-419: 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

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4526-472: 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

4599-477: The needs of the state and the needs of ordinary citizens. In the poem, Pushkin describes the fates of the poor man Evgenii and his beloved Parasha during a severe flood of the Neva . Evgenii curses the statue, furious at Peter the Great for founding a city in such an unsuitable location and indirectly causing the death of his beloved. Coming to life, the horseman chases Evgenii through the city. The poem closes with

4672-516: 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

4745-428: 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

4818-750: 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

4891-508: The statue was later finished. It took 12 years, from 1770 to 1782, to create the Bronze Horseman, including pedestal , horse and rider. The tsar 's face is the work of the young Marie-Anne Collot , then only 18 years old. She had accompanied Falconet as an apprentice on his trip to Russia in 1766. A student of Falconet and Jean-Baptiste Lemoyne , Collot was called Mademoiselle Victoire (Miss Victory) by Diderot. She modelled Peter

4964-438: 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

5037-399: 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

5110-504: Was Falconet, as a misunderstanding between him and the empress turned into a serious conflict. As a result, he was forced to leave Russia four years before the project was completed. Catherine largely forgot about him afterwards, and came to see the Bronze Horseman as her own oeuvre. The statue portrays Peter the Great sitting heroically on his horse, his outstretched arm pointing towards the River Neva . The sculptor wished to capture

5183-640: Was embedded to half its depth in the ground and the area was marshy terrain, the Russians had to develop new methods to dig up and transport the colossal stone. Marinos Carburis (Μαρίνος Χαρμπούρης), a Greek from the Island of Kefallonia and serving as lieutenant-colonel in the Imperial Russian Army , offered to undertake the project. Carburis had studied engineering in Vienna and is considered

5256-527: 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

5329-737: Was inspired by the poem. The statue itself has been seen as the inspiration or model for a similar statue which appears in Joseph Conrad 's 1904 political novel Nostromo , thus implicitly linking the political events in Nostromo with Conrad's 1905 essay "Autocracy and War" on the subject of Russia and his eventual 1912 novel Under Western Eyes (and also with the Pushkin poem and with the political issue of Poland). 59°56′11″N 30°18′08″E  /  59.9364°N 30.3022°E  / 59.9364; 30.3022 Copper Copper

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