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Item:364623101717Native Natural Dendritic Copper Crystal Mineral Specimen ITAUZ MINE KAZAKHSTAN. Click HERE to see hundreds of other amazing items for sale in my store! This specimen weighs 6.60 grams. It measures 24 mm x 20 mm x 9 mm. I offer a shipping discount for customers who combine their payments for multiple purchases into one payment! The discount is regular shipping price for the first item and just 50 cents for each additional item! To be sure you get your shipping discount just make sure all the items you want to purchase are in your cart. Auctions you win are added to your cart automatically. For any "buy it now" items or second chance offers, be sure to click the "add to cart" button, NOT the "buy it now" button. Once all of your items are in your cart just pay for them from your cart and the combined shipping discount should be applied automatically. I offer a money back guarantee on every item I sell. If you are not 100% happy with your purchase just send me a message to let me know and I will buy back the item for your full purchase price. Hi there. I am selling this beautiful dendritic copper mineral specimen. This specimen is from Itauz Mine, Dzhezkazgan, Kazakhstan. If you have any questions, please do not hesitate to ask me. Thanks so much for shopping at my eBay store and have a great day!
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Copper
From Wikipedia, the free encyclopedia
Copper, 29Cu
Native copper (~4 cm in size)
General properties
Pronunciation /ˈkɒpər/
KOP-ər
Appearance red-orange metallic luster
Standard atomic weight (Ar, std) 63.546(3)[1]
nickel ← copper → zinc
Atomic number (Z) 29
Group, period group 11, period 4
Block d-block
Element category transition metal
Electron configuration [Ar] 3d10 4s1
Electrons per shell
2, 8, 18, 1
Physical properties
Phase (at STP) solid
Melting point 1357.77 K (1084.62 °C, 1984.32 °F)
Copper is a chemical element with 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 reddish-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 is one of the few metals that occur in nature in directly usable metallic form (native metals) as opposed to needing extraction from an ore. This led to very early human use, from c. 8000 BC. It was the first metal to be smelted from its ore, c. 5000 BC, the first metal to be cast into a shape in a mold, c. 4000 BC and the first metal to be purposefully alloyed with another metal, tin, to create bronze, c. 3500 BC.[4]
In the Roman era, copper was principally mined on Cyprus, the origin of the name of the metal, from aes сyprium (metal of Cyprus), later corrupted to сuprum, from which the words copper (English), cuivre (French), Koper (Dutch) and Kupfer (German) are all derived.[5] The 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 a green verdigris (or patina). 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 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.[6] The adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight.[7]
A copper disc (99.95% pure) made by continuous casting; etched to reveal crystallites.
Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color.
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 a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper.[8] 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.[9]
The softness of copper partly explains its high electrical conductivity (59.6×106 S/m) and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature.[10] This 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.[8] The maximum permissible current density of copper in open air is approximately 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively.[11]
Copper is one of a few metallic elements with a natural color other than gray or silver.[12] Pure copper is orange-red and acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light.
As with other metals, if copper is put in contact with another metal, galvanic corrosion will occur.[13]
Chemical
Unoxidized copper wire (left) and oxidized copper wire (right).
The East Tower of the Royal Observatory, Edinburgh. The contrast between the refurbished copper installed in 2010 and the green color of the original 1894 copper is clearly seen.
Copper does not react with water, but it does slowly react with atmospheric oxygen to form 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[14] and the Statue of Liberty.[15] Copper tarnishes when exposed to some sulfur compounds, with which it reacts to form various copper sulfides.[16]
Isotopes
Main article: Isotopes of copper
There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper; both have a spin of 3⁄2.[17] The other isotopes are radioactive, with the most stable being 67Cu with a half-life of 61.83 hours.[17] Seven metastable isotopes have been characterized; 68mCu 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+. 64Cu, which has a half-life of 12.7 hours, decays both ways.[18]
62Cu and 64Cu have significant applications. 62Cu is used in 62Cu-PTSM as a radioactive tracer for positron emission tomography.[19]
Occurrence
Native copper from the Keweenaw Peninsula Michigan about 2.5 inches (6.4 cm) long
Copper is produced in massive stars[20] and is present in the Earth's crust in a proportion of about 50 parts per million (ppm).[21] It occurs as native copper, in the copper sulfides chalcopyrite and chalcocite, in the copper carbonates azurite and malachite, and in the copper(I) oxide mineral cuprite.[10] The largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US.[21] Native copper is a polycrystal, with the largest single crystal ever described measuring 4.4×3.2×3.2 cm.[22]
Production
Chuquicamata in Chile is one of the world's largest open pit copper mines.
World production trend
Copper prices 2003–2011 in USD per tonne
See also: List of countries by copper production
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 the British Geological Survey in 2005, Chile was the top producer of copper with at least one-third world share followed by the United States, Indonesia and Peru.[10] 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.[23] 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.[24]
Reserves
See also: Peak copper § Reserves
Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined and smelted has been extracted since 1900,[25] and more than half was extracted the last 24 years. As with many natural resources, the total amount of copper on Earth is vast, with around 1014 tons in 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 years to 60 years, depending on core assumptions such as the growth rate.[26] Recycling is a major source of copper in the modern world.[25] Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of peak copper, analogous to peak oil.
The price of copper has historically been unstable,[27] and it sextupled from the 60-year low of US$0.60/lb (US$1.32/kg) in June 1999 to US$3.75 per pound (US$8.27/kg) in May 2006. It dropped to US$2.40/lb (US$5.29/kg) in February 2007, then rebounded to US$3.50/lb (US$7.71/kg) in April 2007.[28][better source needed] In February 2009, weakening global demand and a steep fall in commodity prices since the previous year's highs left copper prices at US$1.51/lb (US$3.32/kg).[29]
Methods
Main article: Copper extraction techniques
Scheme of flash smelting process
The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2) and to a lesser extent chalcocite (Cu2S).[30] These minerals are concentrated from crushed ores to the level of 10–15% copper by froth flotation or bioleaching.[31] Heating this material with silica in flash smelting removes much of the iron as slag. The process exploits the greater ease of converting iron sulfides into oxides, which in turn react with the silica to form the silicate slag that floats on top of the heated mass. The resulting copper matte, consisting of Cu2S, is roasted to convert all sulfides into oxides:[30]
2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2
The cuprous oxide is converted to blister copper upon heating:
2 Cu2O → 4 Cu + O2
The Sudbury matte process converted only half the sulfide to oxide and then used this oxide to remove the rest of the sulfur as oxide. It was then electrolytically refined and the anode mud exploited for the platinum and gold it contained. This step exploits the relatively easy reduction of copper oxides to copper metal. Natural gas is blown across the blister to remove most of the remaining oxygen and electrorefining is performed on the resulting material to produce pure copper:[32]
Cu2+ + 2 e− → Cu
Flowchart of copper refining (Anode casting plant of Uralelektromed)
Blister copper
Smelting
Reverberatory furnace
Slag removal
Copper casting of anodes
Casting wheel
Anodes removal machine
Anodes take-off
Rail cars
Transportation to the tank house
Flowchart of copper refining (Anode casting plant of Uralelektromed) # Blister copper # Smelting # Reverberatory furnace # Slag removal # Copper casting of anodes # Casting wheel # Anodes removal machine # Anodes take-off # Rail cars # Transportation to the tank house
Recycling
Like aluminium,[33] copper is recyclable without any loss of quality, both from raw state and from manufactured products.[34] In volume, copper is the third most recycled metal after iron and aluminium.[35] An estimated 80% of all copper ever mined is still in use today.[36] According to 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 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.[37]
Alloys
See also: List of copper alloys
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 is one of the most important constituents of silver and carat gold and carat solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys.[38] Some lead-free solders consist of tin alloyed with a small proportion of copper and other metals.[39]
The alloy of copper and nickel, called cupronickel, is used in low-denomination coins, often for the outer cladding. The US 5-cent coin (currently called a nickel) consists of 75% copper and 25% nickel in homogeneous composition. The alloy of 90% copper and 10% nickel, remarkable for its resistance to corrosion, is used for various objects exposed to seawater, though it is vulnerable to the sulfides sometimes found in polluted harbors and estuaries.[40] Alloys of copper with aluminium (about 7%) have a golden color and are used in decorations.[21] 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.[41]
Compounds
A sample of copper(I) oxide.
See also: Category:Copper compounds
Copper forms a rich variety of compounds, usually with oxidation states +1 and +2, which are often called cuprous and cupric, respectively.[42]
Binary compounds
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 the numerous copper sulfides, important examples include copper(I) sulfide and copper(II) sulfide.
Cuprous halides (with chlorine, bromine, and iodine) are known, as are cupric halides with fluorine, chlorine, and bromine. Attempts to prepare copper(II) iodide yield only cuprous iodide and iodine.[42]
2 Cu2+ + 4 I− → 2 CuI + I2
Coordination chemistry
Copper(II) gives a deep blue coloration in the presence of ammonia ligands. The one used here is tetramminecopper(II) sulfate.
Copper forms coordination complexes with ligands. In aqueous solution, copper(II) exists as [Cu(H2O)6]2+. This complex exhibits 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:
Pourbaix diagram for copper in uncomplexed media (anions not other than OH- considered). Ion concentration 0.001 m (mol/kg water). Temperature 25 °C.
Cu2+ + 2 OH− → Cu(OH)2
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 a blue crystalline pentahydrate, the most familiar copper compound in the laboratory. It is used in a fungicide called the Bordeaux mixture.[43]
Ball-and-stick model of the complex [Cu(NH3)4(H2O)2]2+, illustrating the octahedral coordination geometry common for copper(II).
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 the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide.[44] Schweizer's reagent and related complexes with ethylenediamine and other amines dissolve cellulose.[45] Amino acids form very stable chelate complexes with copper(II). Many wet-chemical tests for copper ions exist, one involving potassium ferrocyanide, which gives a brown precipitate with copper(II) salts.
Organocopper chemistry
Main article: Organocopper compound
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;[46] in particular, the last reaction described produces 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[47] and the Sonogashira coupling.[48] Conjugate addition to enones[49] and carbocupration of alkynes[50] can also be achieved with organocopper compounds. Copper(I) forms a variety of weak complexes with alkenes and carbon monoxide, especially in the presence of amine ligands.[51]
Copper(III) and copper(IV)
Copper(III) is most often found in oxides. A simple example is potassium cuprate, KCuO2, a blue-black solid.[52] The most extensively studied copper(III) compounds are the cuprate superconductors. Yttrium barium copper oxide (YBa2Cu3O7) consists of both Cu(II) and Cu(III) centres. Like oxide, fluoride is a highly basic anion[53] and is known to stabilize metal ions in high oxidation states. Both copper(III) and even copper(IV) fluorides are known, K3CuF6 and Cs2CuF6, respectively.[42]
Some copper proteins form oxo complexes, which also feature copper(III).[54] With tetrapeptides, purple-colored copper(III) complexes are stabilized by the deprotonated amide ligands.[55]
Complexes of copper(III) are also found as intermediates in reactions of organocopper compounds.[56] For example, in the Kharasch–Sosnovsky reaction.
History
Copper Age
Main article: Copper Age
A corroded copper ingot from Zakros, Crete, shaped in the form of an animal skin typical in that era.
Many tools during the Chalcolithic Era included copper, such as the blade of this replica of Ötzi's axe
Copper ore (chrysocolla) in Cambrian sandstone from Chalcolithic mines in the Timna Valley, southern Israel.
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 the Middle East;[57] a copper pendant was found in northern Iraq that dates to 8700 BC.[58] Evidence suggests that gold and meteoric iron (but not iron smelting) were the only metals used by humans before copper.[59] 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 the beginning of the Neolithic c. 7500 BC.[60]
Copper smelting was independently invented in different places. It was probably discovered in China before 2800 BC, in Central America around 600 AD, and in West Africa about the 9th or 10th century AD.[61] Investment casting was invented in 4500–4000 BC in Southeast Asia[57] and carbon dating has established mining at Alderley Edge in Cheshire, UK, at 2280 to 1890 BC.[62] Ötzi the Iceman, a male dated from 3300–3200 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.[63] Experience with copper has assisted the development of other metals; in particular, copper smelting led to the discovery of iron smelting.[63] Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC.[64][65] 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.[citation needed]
Bronze Age
Main article: Bronze Age
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.[citation needed] Bronze artifacts from the Vinča culture date to 4500 BC.[66] Sumerian and Egyptian artifacts of copper and bronze alloys date to 3000 BC.[67] 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 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 the Roman Empire.[67]
Antiquity and Middle Ages
In alchemy the symbol for copper was also the symbol for the goddess and planet Venus.
Chalcolithic copper mine in Timna Valley, Negev Desert, Israel.
In Greece, copper was known by the name chalkos (χαλκός). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as aes Cyprium, aes being the generic Latin term for copper alloys and Cyprium from Cyprus, where much copper was mined. The phrase was simplified to cuprum, hence the English copper. Aphrodite (Venus in Rome) represented copper in mythology and alchemy because of its lustrous beauty and its ancient use in producing mirrors; Cyprus was sacred to the goddess. The seven heavenly bodies known to the ancients were associated with the seven metals known in antiquity, and Venus was assigned to copper.[68]
Copper was first used in ancient Britain in about the 3rd or 2nd Century BC. In North America, copper mining began with marginal workings by Native Americans. Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600.[69] Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD. Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century.
The cultural role of copper has been important, particularly in currency. Romans in the 6th through 3rd centuries BC used copper lumps as money. At first, the copper itself was valued, but gradually the shape and look of the copper became more important. Julius Caesar had his own coins made from brass, while Octavianus Augustus Caesar's coins were made from Cu-Pb-Sn alloys. With an estimated annual output of around 15,000 t, Roman copper mining and smelting activities reached a scale unsurpassed until the time of the Industrial Revolution; the provinces most intensely mined were those of Hispania, Cyprus and in Central Europe.[70][71]
The gates of the Temple of Jerusalem used Corinthian bronze treated with depletion gilding.[clarification needed][citation needed] The process was most prevalent in Alexandria, where alchemy is thought to have begun.[72] In ancient India, copper was used in the holistic medical science Ayurveda for surgical instruments and other medical equipment. Ancient Egyptians (~2400 BC) used copper for sterilizing wounds and drinking water, and later to treat headaches, burns, and itching.
Modern period
Acid mine drainage affecting the stream running from the disused Parys Mountain copper mines
The Great Copper Mountain was a mine in Falun, Sweden, that operated from the 10th century to 1992. It satisfied two thirds of Europe's copper consumption in the 17th century and helped fund many of Sweden's wars during that time.[73] It was referred to as the nation's treasury; Sweden had a copper backed currency.[74]
Copper is used in roofing,[14] currency, and for photographic technology known as the daguerreotype. Copper was used in Renaissance sculpture, and was used to construct the Statue of Liberty; copper continues to be used in construction of various types. Copper plating and copper sheathing were widely used to protect the under-water hulls of ships, a technique pioneered by the British Admiralty in the 18th century.[75] The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant, starting its production in 1876.[76] The German scientist Gottfried Osann invented powder metallurgy in 1830 while determining the metal's atomic mass; around then it was discovered that the amount and type of alloying element (e.g., tin) to copper would affect bell tones. Flash smelting was developed by Outokumpu in Finland and first applied at Harjavalta in 1949; the energy-efficient process accounts for 50% of the world's primary copper production.[77]
The Intergovernmental Council of Copper Exporting Countries, formed in 1967 by Chile, Peru, Zaire and Zambia, operated in the copper market as OPEC does in oil, though it never achieved the same influence, particularly because the second-largest producer, the United States, was never a member; it was dissolved in 1988.[78]
Applications
See also: Copper in renewable energy
Assorted copper fittings
The major applications of copper are electrical wire (60%), roofing and plumbing (20%), and industrial machinery (15%). Copper is used mostly as a pure metal, but when greater hardness is required, it is put into such alloys as brass and bronze (5% of total use).[21] For more than two centuries, copper paint has been used on boat hulls to control the growth of plants and shellfish.[79] A small part of the copper supply is used for nutritional supplements and fungicides in agriculture.[43][80] Machining of copper is possible, although alloys are preferred for good machinability in creating intricate parts.
Wire and cable
Main article: Copper wire and cable
Despite competition from other materials, copper remains the preferred electrical conductor in nearly all categories of electrical wiring except overhead electric power transmission where aluminium is often preferred.[81][82] Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronics circuitry, and countless types of electrical equipment.[83] Electrical wiring is the most important market for the copper industry.[84] This includes structural power wiring, power distribution cable, appliance wire, communications cable, automotive wire and cable, and magnet wire. Roughly half of all copper mined is used for electrical wire and cable conductors.[85] Many electrical devices rely on copper wiring because of its multitude of inherent beneficial properties, such as its high electrical conductivity, tensile strength, ductility, creep (deformation) resistance, corrosion resistance, low thermal expansion, high thermal conductivity, ease of soldering, malleability, and ease of installation.