Chemical component, symbol Au and atomic number 79
Gold is a chemical element with the symbol Au ( from latin : aurum ) and atomic number 79, making it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, ductile, and ductile metallic element in a arrant form. Chemically, aureate is a transition metallic element and a group 11 chemical element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in unblock elemental ( native ) form, as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native component flatware ( as electrum ), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less normally, it occurs in minerals as gold compounds, often with tellurium ( gold tellurides ). gold is immune to most acids, though it does dissolve in greenish blue regia ( a concoction of azotic acid and hydrochloric acidic ), forming a soluble tetrachloroaurate anion. Gold is insoluble in azotic acid, which dissolves flatware and free-base metals, a property long used to refine gold and confirm the presence of gold in metallic substances, giving rise to the term acid test. Gold besides dissolves in alkaline solutions of nitrile, which are used in mining and electroplate. Gold dissolves in mercury, forming amalgam alloys, and as the amber acts just as a solute, this is not a chemical reaction. A relatively rare element, [ 6 ] [ 7 ] aureate is a precious metallic that has been used for neologism, jewelry, and early arts throughout recorded history. In the past, a gold standard was frequently implemented as a monetary policy. silent, gold coins ceased to be minted as a circulate currency in the 1930s, and the earth aureate criterion was abandoned for a decree currency system after 1971. In 2020, the world ‘s largest gold producer was China, followed by Russia and Australia. [ 8 ] A sum of around 201,296 tonnes of aureate exists above background, as of 2020. [ 9 ] This is adequate to a block with each side measuring roughly 21.7 meters ( 71 foot ). The worldly concern consumption of newly gold produced is about 50 % in jewelry, 40 % in investments and 10 % in industry. [ 10 ] Gold ‘s high malleability, ductility, resistance to corrosion and most other chemical reactions, and conduction of electricity have led to its continued consumption in corrosion-resistant electrical connectors in all types of computerize devices ( its chief industrial use ). amber is besides used in infrared shielding, colored-glass production, aureate foliation, and tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine .

Characteristics

[11] aureate can be drawn into a monatomic wire, and then stretched more before it breaks . 2 (5.4 sq ft) in area. A gold nugget of 5 millimeter ( 0.20 in ) in size can be hammered into a gold hydrofoil of about 0.5 m ( 5.4 sq foot ) in area. gold is the most ductile of all metals. It can be drawn into a wire of single-atom width, and then stretched well before it breaks. [ 11 ] such nanowires distort via constitution, reorientation and migration of dislocations and crystal twins without noticeable harden. [ 12 ] A individual gram of gold can be beaten into a sheet of 1 square meter ( 11 sq foot ), and an avoirdupois snow leopard into 300 feather feet ( 28 m2 ). Gold leaf can be beaten thin enough to become semi-transparent. The convey light appears green blue sky, because gold powerfully reflects yellow and crimson. [ 13 ] such semi-transparent sheets besides powerfully reflect infrared lightly, making them utilitarian as infrared ( beaming heat ) shields in visors of heat-resistant suits, and in sun-visors for spacesuits. [ 14 ] Gold is a good conductor of heat and electricity. Gold has a density of 19.3 g/cm3, about identical to that of tungsten at 19.25 g/cm3 ; as such, tungsten has been used in forge of aureate bars, such as by plating a tungsten barroom with gold, [ 15 ] [ 16 ] [ 17 ] [ 18 ] or taking an existing gold bar, drilling holes, and replacing the removed gold with tungsten rods. [ 19 ] By comparison, the density of conduct is 11.34 g/cm3, and that of the densest component, osmium, is 22.588±0.015 g/cm3. [ 20 ]

color

Whereas most metals are grey or argent flannel, gold is slightly reddish-yellow. [ 21 ] This semblance is determined by the frequency of plasma oscillations among the metal ‘s valence electrons, in the ultraviolet range for most metals but in the visible range for amber due to relativistic effects affecting the orbitals around gold atoms. [ 22 ] [ 23 ] Similar effects impart a golden imbue to metallic cesium. park colored gold alloys include the classifiable eighteen-karat rose gold created by the summation of copper. Alloys containing palladium or nickel are besides important in commercial jewelry as these produce white aureate alloy. Fourteen-karat gold-copper alloy is closely identical in color to certain bronze alloys, and both may be used to produce police and early badges. Fourteen- and eighteen-karat amber alloys with silver alone look greenish-yellow and are referred to as fleeceable gold. Blue gold can be made by alloying with iron, and purple gold can be made by alloying with aluminum. Less normally, addition of manganese, indium, and other elements can produce more unusual colors of gold for respective applications. [ 24 ] Colloidal gold, used by electron-microscopists, is loss if the particles are small ; larger particles of colloidal gold are blue. [ 25 ]

Isotopes

gold has entirely one stable isotope, 197
Au, which is besides its entirely naturally occurring isotope, so gold is both a mononuclidic and monoisotopic element. thirty-six radioisotopes have been synthesized, ranging in nuclear bulk from 169 to 205. The most stable of these is 195
Au with a half life of 186.1 days. The least static is 171
Au, which decays by proton emission with a half life of 30 µs. Most of gold ‘s radioisotopes with nuclear masses below 197 decay by some combination of proton emission, α decay, and β+ decay. The exceptions are 195
Au, which decays by electron capture, and 196
Au, which decays most often by electron get ( 93 % ) with a minor β− decay path ( 7 % ). [ 26 ] All of gold ‘s radioisotopes with atomic masses above 197 decay by β− decay. [ 27 ] At least 32 nuclear isomers have besides been characterized, ranging in atomic mass from 170 to 200. Within that scope, only 178
Au, 180
Au, 181
Au, 182
Au, and 188
Au do not have isomers. Gold ‘s most stable isomer is 198m2
Au with a half life of 2.27 days. Gold ‘s least stable isomer is 177m2
Au with a half life of only 7 ns. 184m1
Au has three decay paths : β+ decay, isomeric transition, and alpha decay. No early isomer or isotope of gold has three decay paths. [ 27 ]

deduction

The possible product of gold from a more common element, such as leash, has long been a subject of homo inquiry, and the ancient and medieval discipline of chemistry much focused on it ; however, the transmutation of the chemical elements did not become possible until the agreement of nuclear physics in the twentieth century. The beginning synthesis of gold was conducted by japanese physicist Hantaro Nagaoka, who synthesized gold from mercury in 1924 by neutron bombing. [ 28 ] An american team, working without cognition of Nagaoka ‘s prior study, conducted the same experiment in 1941, achieving the lapp resultant role and show that the isotopes of gold produced by it were all radioactive. [ 29 ] In 1980, Glenn Seaborg transmuted several thousand atoms of bismuth into gold at the Lawrence Berkeley Laboratory. [ 30 ] [ 31 ] Gold can be manufactured in a nuclear reactor, but doing so is highly airy and would cost far more than the value of the gold that is produced. [ 32 ]

chemistry

Gold ( III ) chloride solution in water Although gold is the most noble of the lord metals, [ 33 ] [ 34 ] it still forms many divers compounds. The oxidation state of aureate in its compounds ranges from −1 to +5, but Au ( I ) and Au ( III ) dominate its chemistry. Au ( I ), referred to as the aurous ion, is the most common oxidation state of matter with soft ligands such as thioethers, thiolates, and organophosphines. Au ( I ) compounds are typically linear. A beneficial exercise is Au ( CN ) −2, which is the soluble form of amber encountered in mining. The binary star aureate halides, such as AuCl, kind zigzag polymeric chains, again featuring linear coordination at Au. Most drugs based on gold are Au ( I ) derivatives. [ 35 ] Au ( III ) ( referred to as the aurous ) is a coarse oxidation state, and is illustrated by aureate ( III ) chloride, Au2Cl6. The amber atom centers in Au ( III ) complexes, like other d8 compounds, are typically square planar, with chemical bonds that have both covalent and ionic character. amber does not react with oxygen at any temperature [ 36 ] and, up to 100 °C, is insubordinate to attack from ozone. [ 37 ]

A u + O 2 ≠ { \displaystyle Au+O_ { 2 } \neq }

A uranium + O 3 ≠ thyroxine < 100 o C { \displaystyle Au+O_ { 3 } { \overset { \underset { \mathrm { t < 100^ { o } C } } { } } { \neq } } }

Some release halogens react with gold. [ 38 ] Gold is strongly attacked by fluorine at dull-red heating system [ 39 ] to form gold ( III ) fluoride AuF3. Powdered amber reacts with chlorine at 180 °C to form gold ( III ) chloride AuCl3. [ 40 ] Gold reacts with bromine at 140 °C to form gold ( III ) platitude AuBr3, but reacts only very lento with tincture of iodine to form gold ( I ) iodide AuI .

2 Au + 3 F 2 → t 2 AuF 3 { \displaystyle { \ce { 2 Au + 3 F2 – > [ metric ton ] 2 AuF3 } } } 2 Au + 3 Cl 2 → t 2 AuCl 3 { \displaystyle { \ce { 2 Au + 3 Cl2 – > [ deoxythymidine monophosphate ] 2 AuCl3 } } } 2 Au + 2 Br 2 → thyroxine AuBr 3 + AuBr { \displaystyle { \ce { 2 Au + 2 Br2 – > [ metric ton ] AuBr3 + AuBr } } } 2 Au + I 2 → metric ton 2 AuI { \displaystyle { \ce { 2 Au + I2 – > [ thymine ] 2 AuI } } } 2 Au + 6 H 2 SeO 4 → 200 oxygen C Au 2 ( SeO 4 ) 3 + 3 H 2 SeO 3 + 3 H 2 O { \displaystyle { \ce { 2 Au + 6 H2SeO4 – > [ 200^oC ] Au2 ( SeO4 ) 3 + 3 H2SeO3 + 3 H2O } } } Au 4 + HCl + HNO 3 ⟶ H [ AuCl 4 ] + NO ↑ + 2 H 2 O { \displaystyle { \ce { Au+4HCl+HNO3- > H [ AuCl4 ] { } +NO\uparrow +2H2O } } } Oldest fortunate artifacts in the world ( 4600 BC – 4200 BC ) from Varna cemetery, Bulgaria – grave offerings on exposition in Varna Museum Hindush, carrying gold on a yoke, circa 500 BC.[76] An indian tribute-bearer at Apadana, from the Achaemenid satrapy of, carrying gold on a yoke, circa 500 BC . zipa used to cover his body in gold dust, and from his Guatavita goddess in the middle of the sacred lake. This old Muisca tradition became the origin of the legend of El Dorado.
This Muisca raft figure is on display in the Gold Museum, Bogotá, Colombia. The Muisca raft, between circa 600-1600 AD. The trope refers to the ceremony of the caption of El Dorado. Theused to cover his body in gold dust, and from his raft, he offered treasures to thegoddess in the middle of the consecrated lake. This erstwhile Muisca custom became the lineage of the legend of El Dorado. The earliest record metallic element employed by humans appears to be gold, which can be found release or “ native “. humble amounts of natural aureate have been found in spanish caves used during the late Paleolithic period, c. 40,000 BC. [ 77 ] The oldest gold artifacts in the populace are from Bulgaria and are dating spinal column to the fifth millennium BC ( 4,600 BC to 4,200 BC ), such as those found in the Varna Necropolis near Lake Varna and the Black Sea seashore, thought to be the earliest “ well-dated ” discover of gold artifacts in history. [ 78 ] [ 68 ] [ 79 ] [ 80 ] Several prehistoric Bulgarian finds are considered no less old – the fortunate treasures of Hotnitsa, Durankulak, artifacts from the Kurgan liquidation of Yunatsite near Pazardzhik, the gold treasure Sakar, american samoa well as beads and aureate jewelry found in the Kurgan settlement of Provadia – Solnitsata ( “ salt pit ” ). however, Varna aureate is most often called the oldest since this treasure is the largest and most diverse. [ 81 ] Gold artifacts probably made their first appearance in Ancient Egypt at the very begin of the pre-dynastic menstruation, at the end of the fifth millennium BC and the beginning of the fourth, and smelt was developed during the course of the fourth millennium ; gold artifacts appear in the archeology of Lower Mesopotamia during the early 4th millennium. [ 82 ] As of 1990, aureate artifacts found at the Wadi Qana cave cemetery of the 4th millennium BC in West Bank were the earliest from the Levant. [ 83 ] Gold artifacts such as the golden hats and the Nebra phonograph record appeared in Central Europe from the 2nd millennium BC Bronze Age. The oldest know map of a gold mine was drawn in the 19th Dynasty of Ancient Egypt ( 1320–1200 BC ), whereas the first written address to amber was recorded in the 12th Dynasty around 1900 BC. [ 84 ] Egyptian hieroglyph from equally early as 2600 BC report gold, which King Tushratta of the Mitanni claimed was “ more ample than dirt ” in Egypt. [ 85 ] Egypt and specially Nubia had the resources to make them major gold-producing areas for much of history. One of the earliest sleep together maps, known as the Turin Papyrus Map, shows the plan of a amber mine in Nubia together with indications of the local geology. The primitive working methods are described by both Strabo and Diodorus Siculus, and included fire-setting. big mines were besides present across the Red Sea in what is now Saudi Arabia .
gold is mentioned in the Amarna letters numbered 19 [ 86 ] and 26 [ 87 ] from around the fourteenth century BC. [ 88 ] [ 89 ] gold is mentioned frequently in the Old Testament, starting with Genesis 2:11 ( at Havilah ), the fib of the golden calf, and many parts of the temple including the Menorah and the golden altar. In the New Testament, it is included with the gifts of the magus in the first chapters of Matthew. The Book of Revelation 21:21 describes the city of New Jerusalem as having streets “ made of arrant gold, pass as crystal ”. exploitation of gold in the southeast corner of the Black Sea is said to date from the time of Midas, and this gold was authoritative in the establishment of what is probably the worldly concern ‘s earliest coinage in Lydia around 610 BC. [ 90 ] The legend of the golden wool dating from eighth hundred BCE may refer to the use of fleeces to trap gold scatter from placer deposits in the ancient worldly concern. From the 6th or fifth century BC, the Chu ( state ) circulated the Ying Yuan, one kind of squarely gold mint. In Roman metallurgy, modern methods for extracting gold on a large scale were developed by introducing hydraulic mining methods, particularly in Hispania from 25 BC onwards and in Dacia from 106 AD onwards. One of their largest mines was at Las Medulas in León, where seven long aqueducts enabled them to sluice most of a large alluvial deposit. The mines at Roşia Montană in Transylvania were besides very large, and until very recently, still mined by opencast methods. They besides exploited smaller deposits in Britain, such as placer and hard-rock deposits at Dolaucothi. The diverse methods they used are well described by Pliny the Elder in his encyclopedia Naturalis Historia written towards the end of the inaugural hundred AD. During Mansa Musa ‘s ( rule of the Mali Empire from 1312 to 1337 ) hajj to Mecca in 1324, he passed through Cairo in July 1324, and was reportedly accompanied by a camel prepare that included thousands of people and about a hundred camels where he gave away so much amber that it depressed the price in Egypt for over a decade, causing high ostentation. [ 91 ] A contemporary Arab historian remarked :

amber was at a high price in Egypt until they came in that year. The mithqal did not go below 25 dirhams and was generally above, but from that time its prize fell and it cheapened in monetary value and has remained cheap public treasury nowadays. The mithqal does not exceed 22 dirhams or less. This has been the state of affairs for about twelve years until this day by reason of the large sum of gold which they brought into Egypt and spent there [ … ] .Chihab Al-Umari, Kingdom of Mali[92]

[93] Gold coin of Eucratides I ( 171–145 BC ), one of the Hellenistic rulers of ancient Ai-Khanoum. This is the largest known gold coin minted in ancientness ( 169.2 gigabyte ( 5.97 oz ) ; 58 millimeter ( 2.3 in ) ). The european exploration of the Americas was fueled in no little depart by reports of the gold ornaments displayed in capital profusion by native american peoples, specially in Mesoamerica, Peru, Ecuador and Colombia. The Aztecs regarded aureate as the product of the gods, calling it literally “ god body waste ” ( teocuitlatl in Nahuatl ), and after Moctezuma II was killed, most of this gold was shipped to Spain. [ 94 ] however, for the autochthonal peoples of North America aureate was considered useless and they saw much greater value in early minerals which were directly related to their utility, such as obsidian, flinty, and slate. [ 95 ] El Dorado is applied to a fabled history in which cherished stones were found in fabulous abundance along with gold coins. The concept of El Dorado undergo several transformations, and finally accounts of the previous myth were besides combined with those of a fabled lost city. El Dorado, was the terminus used by the spanish Empire to describe a fabulous tribal chief ( zipa ) of the Muisca native people in Colombia, who, as an initiation rite, covered himself with gold dust and submerged in Lake Guatavita. The legends surrounding El Dorado changed over time, as it went from being a man, to a city, to a kingdom, and then ultimately to an empire. Beginning in the early advanced period, european exploration and colonization of West Africa was driven in big part by reports of gold deposits in the region, which was finally referred to by Europeans as the “ Gold Coast “. [ 96 ] From the belated 15th to early 19th centuries, european deal in the region was chiefly focused in amber, along with bone and slaves. [ 97 ] The amber deal in West Africa was dominated by the Ashanti Empire, who initially traded with the portuguese before branching out and trading with British, French, Spanish and danish merchants. [ 98 ] british desires to secure control of West African gold deposits played a character in the Anglo-Ashanti wars of the late nineteenth century, which saw the Ashanti Empire annexed by Britain. [ 99 ] Gold played a character in western culture, as a causal agent for hope and of corruption, as told in children ‘s fables such as Rumpelstiltskin —where Rumpelstiltskin turns hay into aureate for the peasant ‘s daughter in render for her child when she becomes a princess—and the steal of the hen that lays gold eggs in Jack and the Beanstalk. The acme loot at the Olympic Games and many other sports competitions is the gold decoration. 75 % of the soon accounted for aureate has been extracted since 1910, two-thirds since 1950. One main goal of the alchemists was to produce gold from other substances, such as contribute — presumably by the interaction with a fabulous message called the philosopher ‘s stone. Trying to produce aureate led the alchemists to systematically find out what can be done with substances, and this laid the initiation for today ‘s chemistry, which can produce amber ( albeit uneconomically ) by using nuclear transformation. [ 100 ] Their symbol for gold was the traffic circle with a point at its center ( ☉ ), which was besides the astrological symbol and the ancient taiwanese character for the Sun. The Dome of the Rock is covered with an ultra-thin gold glassy. The Sikh Golden temple, the Harmandir Sahib, is a build covered with gold. similarly the Wat Phra Kaew emerald Buddhist temple ( wat ) in Thailand has cosmetic gold-leafed statues and roof. Some european king and fagot ‘s crowns were made of gold, and gold was used for the bridal crown since antiquity. An ancient Talmudic textbook circa 100 AD identify Rachel, wife of Rabbi Akiva, receiving a “ Jerusalem of Gold ” ( crown ). A greek burial crown made of gold was found in a grave circa 370 BC .

etymology

Beowulf An early on citation of amber in the “ gold ” is connate with similar words in many Germanic languages, deriving via Proto-Germanic * gulþą from Proto-Indo-European * ǵʰelh₃- ( “ to shine, to gleam ; to be yellow or green ” ). [ 101 ] [ 102 ] The symbol Au is from the latin : aurum, the Latin word for “ gold ”. [ 103 ] The Proto-Indo-European ancestor of aurum was *h₂é-h₂us-o-, meaning “ burn ”. This give voice is derived from the lapp settle ( Proto-Indo-European *h₂u̯es- “ to dawn ” ) as *h₂éu̯sōs, the ancestor of the Latin parole Aurora, “ dawn ”. [ 104 ] This etymological relationship is presumably behind the frequent claim in scientific publications that aurum meant “ shining dawn ”. [ 105 ]

acculturation

outside chemistry, gold is mentioned in a variety show of expressions, most often associated with intrinsic worth. [ 44 ] Great homo achievements are frequently rewarded with gold, in the form of gold medals, gold trophies and other decorations. Winners of athletic events and early grade competitions are normally awarded a gold decoration. many awards such as the Nobel Prize are made from gold adenine well. early prize statues and prizes are depicted in gold or are gold plat ( such as the Academy Awards, the Golden Globe Awards, the Emmy Awards, the Palme d’Or, and the british Academy Film Awards ). Aristotle in his ethics used gold symbolism when referring to what is now known as the aureate bastardly. similarly, gold is associated with perfect or divine principles, such as in the case of the golden proportion and the aureate rule.

Read more: The First Coins and the Birth of Coinage

gold is farther associated with the wisdom of aging and fruition. The fiftieth marry anniversary is golden. A person ‘s most valued or most successful latter years are sometimes considered “ aureate years ”. The height of a culture is referred to as a gold long time .

religion

In some forms of Christianity and Judaism, gold has been associated both with holiness and evil. In the Book of Exodus, the Golden Calf is a symbol of idolatry, while in the Book of Genesis, Abraham was said to be rich people in amber and flatware, and Moses was instructed to cover the Mercy Seat of the Ark of the Covenant with pure gold. In Byzantine iconography the aura of Christ, Mary and the christian saints are frequently golden. In Islam, [ 106 ] amber ( along with silk ) [ 107 ] [ 108 ] is often cited as being forbid for men to wear. [ 109 ] Abu Bakr al-Jazaeri, quoting a sunnah, said that “ [ metric ton ] he wearing of silk and gold are forbidden on the males of my nation, and they are lawful to their women ”. [ 110 ] This, however, has not been enforced systematically throughout history, e.g. in the Ottoman Empire. [ 111 ] Further, little aureate accents on clothing, such as in embellishment, may be permitted. [ 112 ] According to Christopher Columbus, those who had something of gold were in monomania of something of great value on Earth and a meaning to even help souls to paradise. [ 113 ] marry rings are typically made of gold. It is retentive durable and unaffected by the passage of time and may aid in the hoop symbolism of endless vows before God and the perfection the marriage signifies. In Orthodox Christian marriage ceremonies, the wed couple is adorned with a golden pennant ( though some choose for wreaths, alternatively ) during the ceremony, an amalgamation of emblematic rites. On 24 August 2020, israeli archaeologists discovered a treasure trove of early Islamic gold coins near the central city of Yavne. psychoanalysis of the highly rare collection of 425 gold coins indicated that they were from the late ninth century. Dating to around 1,100 years back, the aureate coins were from the Abbasid Caliphate. [ 114 ]

product

Time vogue of gold output According to the United States Geological Survey in 2016, about 5,726,000,000 troy ounces ( 178,100 t ) of gold has been accounted for, of which 85 % remains in active practice. [ 115 ]

mine and prospect

A miner underground at Pumsaint amber mine, Wales ; c. 1938. Since the 1880s, South Africa has been the informant of a big proportion of the world ‘s gold supply, and about 22 % of the gold presently accounted is from South Africa. product in 1970 accounted for 79 % of the populace add, about 1,480 tonnes. In 2007 China ( with 276 tonnes ) overtook South Africa as the global ‘s largest aureate producer, the first time since 1905 that South Africa had not been the largest. [ 116 ] In 2020, China was the global ‘s run gold-mining state, followed in order by Russia, Australia, the United States, Canada, and Ghana. [ 8 ]
Japan. proportional size of an 860 kilogram ( 1,900 pound ) block of gold ore and the 30 guanine ( 0.96 ozt ) of gold that can be extracted from it, Toi gold mine In South America, the controversial visualize Pascua Lama aims at exploitation of rich fields in the high mountains of Atacama Desert, at the molding between Chile and Argentina. It has been estimated that up to one-fourth of the annual global gold production originates from artisanal or minor scale mine. [ 117 ] [ 118 ] [ 119 ] The city of Johannesburg located in South Africa was founded as a result of the Witwatersrand Gold Rush which resulted in the discovery of some of the largest natural aureate deposits in recorded history. The gold fields are confined to the northern and north-western edges of the Witwatersrand washbasin, which is a 5–7 kilometer ( 3.1–4.3 nautical mile ) compact layer of archean rocks located, in most places, deep under the Free State, Gauteng and surrounding provinces. [ 120 ] These Witwatersrand rocks are exposed at the surface on the Witwatersrand, in and around Johannesburg, but besides in isolate patches to the southeast and southwest of Johannesburg, american samoa well as in an arc around the Vredefort Dome which lies close to the center of the Witwatersrand basin. [ 64 ] [ 120 ] From these coat exposures the washbasin dips extensively, requiring some of the mine to occur at depths of about 4,000 megabyte ( 13,000 foot ), making them, particularly the Savuka and TauTona mines to the southwest of Johannesburg, the deepest mines on land. The gold is found only in six areas where archean rivers from the north and northwest formed extensive gravelly Braided river delta before draining into the “ Witwatersrand ocean ” where the rest of the Witwatersrand sediments were deposited. [ 120 ] The Second Boer War of 1899–1901 between the british Empire and the Afrikaner Boers was at least partially over the rights of miners and possession of the amber wealth in South Africa .
During the nineteenth hundred, gold rushes occurred whenever large gold deposits were discovered. The first documented discovery of gold in the United States was at the Reed Gold Mine near Georgeville, North Carolina in 1803. [ 121 ] The first major aureate strickle in the United States occurred in a little north Georgia town called Dahlonega. [ 122 ] Further gold rushes occurred in California, Colorado, the Black Hills, Otago in New Zealand, a number of locations across Australia, Witwatersrand in South Africa, and the Klondike in Canada. Grasberg mine located in Papua, Indonesia is the largest gold mine in the world. [ 123 ]

extraction and refine

Gold Nuggets found in Arizona Gold extraction is most economical in big, easily mined deposits. Ore grades equally little as 0.5 parts per million ( ppm ) can be economic. typical ore grades in open-pit mines are 1–5 ppm ; ore grades in metro or unvoiced rock mines are normally at least 3 ppm. Because ore grades of 30 ppm are normally needed before gold is visible to the bare center, in most amber mines the gold is inconspicuous. The average gold mining and extraction costs were about $ 317 per troy snow leopard in 2007, but these can vary widely depending on mine character and ore quality ; global mine production amounted to 2,471.1 tonnes. [ 124 ] After initial production, gold is much subsequently refined industrially by the Wohlwill action which is based on electrolysis or by the Miller process, that is chlorination in the thaw. The Wohlwill march results in higher honor, but is more complex and is only applied in minor installations. [ 125 ] [ 126 ] other methods of assaying and purifying smaller amounts of gold include parting and inquartation angstrom good as cupellation, or refining methods based on the adjournment of amber in greenish blue regia. [ 127 ] As of 2020, the come of carbon dioxide CO2 produced in mining a kilogram of gold is 16 tonnes, while recycling a kilogram of amber produces 53 kilogram of CO2 equivalent. approximately 30 percentage of the global aureate provision is recycled and not mined as of 2020. [ 128 ] Corporations are starting to adopt aureate recycling including jewelry companies such as Generation Collection and computer companies including Dell. [ 129 ]

pulmonary tuberculosis

The consumption of gold produced in the world is about 50 % in jewelry, 40 % in investments, and 10 % in diligence. [ 10 ] [ 133 ] According to the World Gold Council, China was the populace ‘s largest single consumer of aureate in 2013, overtaking India. [ 134 ]

befoulment

Gold production is associated with contribution to hazardous pollution. [ 135 ] [ 136 ] low-grade amber ore may contain less than one ppm gold alloy ; such ore is land and desegregate with sodium cyanide to dissolve the gold. Cyanide is a highly poisonous chemical, which can kill living creatures when exposed in moment quantities. many nitrile spills [ 137 ] from gold mines have occurred in both train and developing countries which killed aquatic life in long stretches of affect rivers. Environmentalists consider these events major environmental disasters. [ 138 ] [ 139 ] Thirty tons of used ore is dumped as consume for producing one troy snow leopard of amber. [ 140 ] Gold ore dumps are the beginning of many grave elements such as cadmium, tip, zinc, copper, arsenic, selenium and mercury. When sulfide-bearing minerals in these ore dumps are exposed to atmosphere and water system, the sulfide transforms into sulphuric acid which in turn dissolves these heavy metals facilitating their passage into open water and reason water. This process is called acid mine drain. These gold ore dumps are long term, highly hazardous wastes second only to nuclear barren dumps. [ 140 ] It was once common to use mercury to recover gold from ore, but today the use of mercury is largely limited to small-scale individual miners. [ 141 ] Minute quantities of mercury compounds can reach water system bodies, causing heavy metal contamination. Mercury can then enter into the homo food chain in the form of methylmercury. Mercury poisoning in humans causes incurable brain function wrong and austere retardation. [ 142 ] Gold extraction is besides a highly energy intensive industry, extracting ore from deep mines and grinding the large quantity of ore for further chemical extraction requires closely 25 kWh of electricity per gram of gold produced. [ 143 ]

Monetary use

amber has been widely used throughout the earth as money, [ 144 ] for efficient indirect exchange ( versus barter ), and to store wealth in hoards. For switch over purposes, mints produce standardized gold bullion coins, bars and other units of situate burden and honor. The first know coins containing gold were struck in Lydia, Asia Minor, around 600 BC. [ 90 ] The talent coin of gold in consumption during the periods of grecian history both before and during the time of the life sentence of Homer weighed between 8.42 and 8.75 grams. [ 145 ] From an earlier preference in using silver medal, european economies re-established the mint of gold as coinage during the thirteenth and fourteenth centuries. [ 146 ] Bills ( that mature into gold coin ) and gold certificates ( convertible into gold mint at the issuing bank ) added to the circulating stock of gold standard money in most nineteenth century industrial economies. In training for World War I the warring nations moved to fractional gold standards, inflating their currencies to finance the war effort. Post-war, the triumphant countries, most notably Britain, gradually restored gold-convertibility, but international flows of gold via bills of switch over remained embargo ; international shipments were made entirely for bilateral trades or to pay war reparations. After World War II amber was replaced by a system of nominally convertible currencies related by repair exchange rates following the Bretton Woods system. aureate standards and the direct convertibility of currencies to gold have been abandoned by world governments, led in 1971 by the United States ‘ refusal to redeem its dollars in gold. Fiat currency immediately fills most monetary roles. Switzerland was the survive country to tie its currentness to amber ; it backed 40 % of its rate until the swiss joined the International Monetary Fund in 1999. [ 147 ] cardinal banks continue to keep a share of their liquid reserves as amber in some form, and metals exchanges such as the London Bullion Market Association still clear transactions denominated in gold, including future delivery contracts. today, gold mine end product is declining. [ 148 ] With the astute increase of economies in the twentieth hundred, and increasing foreign exchange, the world ‘s aureate reserves and their deal market have become a small fraction of all markets and fix exchange rates of currencies to gold have been replaced by floating prices for gold and gold future sign. Though the amber malcolm stock grows by only 1 or 2 % per year, very little metallic is irretrievably consumed. Inventory above crunch would satisfy many decades of industrial and even craftsman uses at stream prices. The gold proportion ( fineness ) of debase is measured by karat ( potassium ). Pure gold ( commercially termed fine gold ) is designated as 24 karat, abbreviated 24k. english gold coins intended for circulation from 1526 into the 1930s were typically a criterion 22k alloy called pennant gold, [ 149 ] for hardness ( american gold coins for circulation after 1837 hold an debase of 0.900 ticket gold, or 21.6 karat ). [ 150 ] Although the prices of some platinum group metals can be much higher, aureate has long been considered the most desirable of cherished metals, and its value has been used as the standard for many currencies. gold has been used as a symbol for purity, value, royalty, and particularly roles that combine these properties. Gold as a sign of wealth and prestige was ridiculed by Thomas More in his treatise Utopia. On that fanciful island, amber is so abundant that it is used to make chains for slaves, tableware, and flush toilet seats. When ambassadors from other countries arrive, dressed in ostentatious gold jewels and badges, the Utopians mistake them for humble servants, paying court alternatively to the most modestly dressed of their party. The ISO 4217 currency code of aureate is XAU. [ 151 ] Many holders of amber memory it in kind of bullion coins or bars as a hedge against inflation or other economic disruptions, though its efficacy as such has been questioned ; historically, it has not proven itself dependable as a hedging musical instrument. [ 152 ] Modern bullion coins for investment or collector purposes do not require good mechanical wear properties ; they are typically fine gold at 24k, although the American Gold Eagle and the british gold sovereign continue to be minted in 22k ( 0.92 ) alloy in historical custom, and the south african Krugerrand, first released in 1967, is besides 22k ( 0.92 ). [ 153 ] The special issue Canadian Gold Maple Leaf coin contains the highest purity gold of any bullion coin, at 99.999 % or 0.99999, while the popular issue Canadian Gold Maple Leaf coin has a honor of 99.99 %. In 2006, the United States Mint began producing the american english Buffalo amber bullion coin with a purity of 99.99 %. The australian Gold Kangaroos were first coined in 1986 as the Australian Gold Nugget but changed the reverse design in 1989. other modern coins include the austrian Vienna Philharmonic bullion coin and the Chinese Gold Panda. [ 154 ]

price

gold price history in 1960–2020. As of September 2017, gold is valued at around $ 42 per gram ( $ 1,300 per troy snow leopard ). Like early cherished metals, gold is measured by troy weight and by grams. The proportion of gold in the alloy is measured by karat ( kilobyte ), with 24 karat ( 24k ) being arrant gold ( 100 % ), and lower karat numbers proportionately less ( 18k = 75 % ). The purity of a gold bar or coin can besides be expressed as a decimal fraction number ranging from 0 to 1, known as the millesimal fineness, such as 0.995 being about arrant. The price of gold is determined through trade in the gold and derivatives markets, but a procedure known as the Gold Fixing in London, originating in September 1919, provides a daily benchmark price to the diligence. The good afternoon fix was introduced in 1968 to provide a price when US markets are open. [ 155 ]

history

historically gold neologism was wide used as currentness ; when paper money was introduced, it typically was a receipt redeemable for gold coin or bullion. In a monetary system known as the gold standard, a certain weight of amber was given the name of a whole of currentness. For a long period, the United States government set the value of the US dollar therefore that one troy snow leopard was equal to $ 20.67 ( $ 0.665 per gram ), but in 1934 the dollar was devalued to $ 35.00 per troy ounce ( $ 0.889/g ). By 1961, it was becoming hard to maintain this price, and a pool of US and european banks agreed to manipulate the market to prevent foster currency devaluation against increased aureate demand. [ 156 ] On 17 March 1968, economic circumstances [ clarification needed ] caused the collapse of the amber consortium, and a two-tiered pricing scheme was established whereby aureate was hush used to settle international accounts at the old $ 35.00 per troy snow leopard ( $ 1.13/g ) but the price of gold on the private market was allowed to fluctuate ; this two-tiered price system was abandoned in 1975 when the monetary value of gold was left to find its free-market level. [ citation needed ] Central banks hush hold historic gold reserves as a store of value although the level has broadly been declining. [ citation needed ] The largest gold depository in the universe is that of the U.S. Federal Reserve Bank in New York, which holds about 3 % [ 157 ] of the gold known to exist and accounted for today, as does the similarly ladle U.S. Bullion Depository at Fort Knox. In 2005 the World Gold Council estimated sum ball-shaped aureate provision to be 3,859 tonnes and necessitate to be 3,754 tonnes, giving a excess of 105 tonnes. [ 158 ] After 15 August 1971 Nixon shock, the price began to greatly increase, [ 159 ] and between 1968 and 2000 the price of aureate ranged widely, from a high of $ 850 per troy ounce ( $ 27.33/g ) on 21 January 1980, to a low of $ 252.90 per troy ounce ( $ 8.13/g ) on 21 June 1999 ( London Gold Fixing ). [ 160 ] Prices increased quickly from 2001, but the 1980 high was not exceeded until 3 January 2008, when a new maximal of $ 865.35 per troy ounce was set. [ 161 ] Another record price was set on 17 March 2008, at $ 1023.50 per troy ounce ( $ 32.91/g ). [ 161 ] In deep 2009, gold markets experienced renewed momentum upwards due to increased need and a weakening US dollar. [ citation needed ] On 2 December 2009, gold reached a new high closure at $ 1,217.23. [ 162 ] Gold far rallied hitting raw highs in May 2010 after the European Union debt crisis prompted far purchase of gold as a safe asset. [ 163 ] [ 164 ] On 1 March 2011, gold hit a new all-time high of $ 1432.57, based on investor concerns regarding ongoing unrest in North Africa deoxyadenosine monophosphate well as in the Middle East. [ 165 ] From April 2001 to August 2011, spot gold prices more than quintupled in prize against the US dollar, hitting a new all-time high gear of $ 1,913.50 on 23 August 2011, [ 166 ] prompting speculation that the long layman bear market had ended and a talk through one’s hat market had returned. [ 167 ] however, the price then began a behind worsen towards $ 1200 per troy ounce in recently 2014 and 2015. In August 2020, the aureate monetary value picked up to US $ 2060 per snow leopard after a complexive growth of 59 % from August 2018 to October 2020, a period during which it outplaced the Nasdaq entire return of 54 %. [ 168 ] gold futures are traded on the COMEX commute. [ 169 ] These contacts are priced in USD per troy ounce ( 1 troy ounce = 31.1034768 grams ). [ 170 ] Below are the CQG contract specifications outlining the futures contracts :

Contract Specifications[169]

Gold (GCA)
Exchange:	COMEX
Sector:	Metal
Tick Size:	0.1
Tick Value:	10 USD
BPV:	100
Denomination:	USD
Decimal Place:	1

other applications

jewelry

Because of the effeminacy of pure ( 24k ) aureate, it is normally alloyed with base metals for use in jewelry, altering its unfeelingness and ductility, melting point, color and early properties. Alloys with lower karat rate, typically 22k, 18k, 14k or 10k, incorporate higher percentages of copper or other base metals or silver or palladium in the admixture. [ 24 ] Nickel is toxic, and its release from nickel white gold is controlled by legislation in Europe. [ 24 ] Palladium-gold alloys are more expensive than those using nickel. [ 171 ] High-karat white amber alloys are more insubordinate to corrosion than are either pure silver medal or greatest ash grey. The japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce cosmetic wood-grain effects. By 2014, the gold jewelry industry was escalating despite a dip in amber prices. demand in the first quarter of 2014 pushed employee turnover to $ 23.7 billion according to a World Gold Council composition. Gold solder is used for joining the components of gold jewelry by high-temperature heavily solder or braze. If the oeuvre is to be of hallmarking quality, the amber solder alloy must match the daintiness ( purity ) of the work, and admixture formulas are manufactured to color-match yellow and white aureate. Gold solder is normally made in at least three melting-point ranges referred to as Easy, Medium and Hard. By using the intemperate, high-melting orient solder first, followed by solders with increasingly lower melting points, goldsmiths can assemble complex items with respective separate soldered joints. gold can besides be made into weave and used in embellishment .

Electronics

merely 10 % of the universe consumption of new gold produced goes to diligence, [ 10 ] but by far the most significant industrial use for new gold is in fabrication of corrosion-free electrical connectors in computers and other electric devices. For exemplar, according to the World Gold Council, a typical cellular telephone phone may contain 50 milligram of gold, worth about 50 cents. But since about one billion cell phones are produced each class, a gold value of 50 cents in each phone adds to $ 500 million in gold from just this lotion. [ 172 ] Though amber is attacked by exempt chlorine, its good conduction and general resistance to oxidation and corrosion in early environments ( including resistance to non-chlorinated acids ) has led to its widespread industrial use in the electronic era as a thin-layer coating on electric connectors, thereby ensuring good association. For exemplar, gold is used in the connectors of the more expensive electronics cables, such as audio, video recording and USB cables. The benefit of using gold over other connection metals such as tin in these applications has been debated ; gold connectors are frequently criticized by audio-visual experts as unnecessary for most consumers and seen as merely a market ploy. however, the consumption of gold in other applications in electronic skid contacts in highly humid or corrosive atmospheres, and in use for contacts with a very high failure monetary value ( certain computers, communications equipment, spacecraft, jet aircraft engines ) remains very common. [ 173 ] Besides sliding electric contacts, gold is besides used in electrical contacts because of its resistor to corrosion, electric conduction, ductility and lack of toxicity. [ 174 ] Switch contacts are broadly subjected to more acute corrosion stress than are sliding contacts. Fine gold wires are used to connect semiconductor device devices to their packages through a process known as telegram bond. The concentration of free electrons in gold alloy is 5.91×1022 cm−3. [ 175 ] Gold is highly conductive to electricity, and has been used for electrical wiring in some high-octane applications ( only silver and copper are more conductive per volume, but gold has the advantage of corrosion immunity ). For model, aureate electrical wires were used during some of the Manhattan Project ‘s atomic experiments, but big high-current silver wires were used in the calutron isotope centrifuge magnets in the stick out. It is estimated that 16 % of the populace ‘s presently-accounted-for gold and 22 % of the earth ‘s silver is contained in electronic technology in Japan. [ 176 ]

medicine

Metallic and gold compounds have long been used for medicative purposes. Gold, normally as the metal, is possibly the most anciently administered music ( apparently by shamanic practitioners ) [ 177 ] and known to Dioscorides. [ 178 ] [ 179 ] In chivalric times, amber was much seen as beneficial for the health, in the impression that something then rare and beautiful could not be anything but goodly. even some modern esotericists and forms of option music delegate metallic gold a healing power. In the nineteenth century aureate had a reputation as an minor tranquilizer, a therapy for anxious disorders. Depression, epilepsy, migraine, and glandular problems such as amenorrhea and powerlessness were treated, and most notably dipsomania ( Keeley, 1897 ). [ 180 ] The apparent paradox of the actual toxicology of the means suggests the possibility of dangerous gaps in the reason of the action of gold in physiology. [ 181 ] entirely salts and radioisotopes of aureate are of pharmacological rate, since elemental ( metallic ) gold is inert to all chemicals it encounters inside the soundbox ( for example, absorb gold can not be attacked by stomach acid ). Some gold salts do have anti-inflammatory properties and at present two are still used as pharmaceuticals in the treatment of arthritis and other exchangeable conditions in the US ( sodium aurothiomalate and auranofin ). These drugs have been explored as a mean to help to reduce the pain and intumescence of arthritic arthritis, and besides ( historically ) against tuberculosis and some parasites. [ 182 ] Gold alloys are used in corrective dentistry, specially in tooth restorations, such as crowns and permanent bridges. The gold alloy ‘ flimsy malleability facilitates the initiation of a superscript molar mating surface with early teeth and produces results that are broadly more satisfactory than those produced by the creation of porcelain crowns. The use of aureate crowns in more big teeth such as incisors is favored in some cultures and discouraged in others. Colloidal gold preparations ( suspensions of gold nanoparticles ) in water are intensely red- colored, and can be made with tightly controlled particle sizes up to a few tens of nanometers across by decrease of gold chloride with citrate or ascorbate ions. Colloidal gold is used in research applications in medicine, biology and materials science. The technique of immunogold labeling exploits the ability of the gold particles to adsorb protein molecules onto their surfaces. Colloidal gold particles coated with specific antibodies can be used as probes for the bearing and position of antigens on the surfaces of cells. [ 183 ] In ultrathin sections of tissues viewed by electron microscopy, the immunogold labels appear as highly dense round spots at the side of the antigen. [ 184 ] gold, or alloys of aureate and palladium, are applied as conductive coat to biological specimens and other nonconductive materials such as plastics and glass to be viewed in a scanning electron microscope. The coating, which is normally applied by sputtering with an argon plasma, has a triple function in this application. Gold ‘s very high electric conduction drains electrical charge to earth, and its very high concentration provides stopping world power for electrons in the electron beam, helping to limit the astuteness to which the electron beam penetrates the specimen. This improves definition of the position and topography of the specimen surface and increases the spatial resolution of the image. Gold besides produces a high end product of secondary coil electrons when irradiated by an electron beam, and these low-energy electrons are the most normally used bespeak source used in the scan electron microscope. [ 185 ] The isotope gold-198 ( half life 2.7 days ) is used in nuclear medicine, in some cancer treatments and for treating other diseases. [ 186 ] [ 187 ]

cuisine

assortment

Kamakshi Amman Temple with golden roof, Kanchipuram

perniciousness

Pure metallic ( elemental ) gold is non-toxic and non-irritating when ingested [ 199 ] and is sometimes used as a food decoration in the form of amber leaf. [ 200 ] Metallic gold is besides a part of the alcoholic drinks Goldschläger, Gold Strike, and Goldwasser. Metallic gold is approved as a food additive in the EU ( E175 in the Codex Alimentarius ). Although the aureate ion is toxic, the acceptance of metallic gold as a food linear is due to its relative chemical inertness, and resistor to being corroded or transformed into soluble salts ( gold compounds ) by any know chemical process which would be encountered in the human soundbox. soluble compounds ( gold salts ) such as amber chloride are toxic to the liver and kidneys. Common nitrile salts of gold such as potassium gold nitrile, used in amber electroplate, are toxic by virtue of both their cyanide and gold content. There are rare cases of deadly gold poison from potassium gold cyanide. [ 201 ] [ 202 ] Gold perniciousness can be ameliorated with chelation therapy with an agent such as dimercaprol. Gold metal was voted Allergen of the year in 2001 by the American Contact Dermatitis Society ; gold contact allergies affect by and large women. [ 203 ] Despite this, gold is a relatively non-potent contact allergen, in comparison with metals like nickel. [ 204 ] A sample of the fungus Aspergillus niger was found growing from amber mine solution ; and was found to contain cyano metallic element complexes, such as aureate, silver, copper, iron and zinc. The fungus besides plays a role in the solubilization of heavy metallic sulfides. [ 205 ]

See besides

Iron pyrite or “ horse around ‘s gold ”

References

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