# Gold Canonical: https://web4.xpay.bi/en/wiki/wp-en-12240/ Language: en Published: 2026-10-30T17:57:31.143Z Updated: 2026-10-30T17:57:31.143Z Gold is a chemical element; its chemical symbol is Au (from Latin aurum) and atomic number 79. In its pure form, it is a bright-metallic-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactive chemical elements, being the second lowest in the reactivity series, with only pl ## Key facts ## Overview Gold is a chemical element; its chemical symbol is Au (from Latin aurum) and atomic number 79. In its pure form, it is a bright-metallic-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactive chemical elements, being the second lowest in the reactivity series, with only platinum ranked as less reactive. Gold is solid under standard conditions. Gold often occurs as the free element (native state), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as in electrum), naturally alloyed with other metals such as copper, platinum, and palladium, as well as mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), forming a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid alone, which dissolves silver and 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 dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. Gold also dissolves in mercury, forming amalgam alloys, and as the gold acts simply as a solute, this is not a chemical reaction. A relatively rare element when compared to silver (though thirty times more common than platinum), gold is a precious metal that has been used for coinage, jewelry, and other works of art throughout recorded history. In the past, a gold standard was often implemented as a monetary policy. Most gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after the Nixon shock measures of 1971. In 2023, the world's largest gold producer was China, followed by Russia and Australia. As of 2020, a total of around 201,296 tonnes of gold exist above ground. If all of this gold were put together into a cube shape, each of its sides would measure 21.7 meters (71 ft). The world's consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, as well as conductivity of electricity have led to its continued use in corrosion-resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, the production of colored glass, gold leafing, and tooth restoration. Auranofin is a gold-containing drug used to treat rheumatoid arthritis. ## Etymology Gold is cognate 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'. The symbol Au is from the Latin aurum 'gold'. The Proto-Indo-European ancestor of aurum was \*h₂é-h₂us-o-, meaning 'glow'. This word is derived from the same root (Proto-Indo-European \*h₂u̯es- 'to dawn') as \*h₂éu̯sōs, the ancestor of the Latin word aurora 'dawn'. This etymological relationship is presumably behind the frequent claim in scientific publications that aurum meant 'shining dawn'. ## Characteristics Gold is the most malleable metal. It can be drawn into a wire of single-atom width, and then stretched considerably before it breaks. Such nanowires distort via the formation, reorientation, and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter (11 sq ft), and an avoirdupois ounce into 28 square meters (300 sq ft). Gold leaf can be beaten thin enough to become semi-transparent. Light transmitted through gold appears greenish-blue, because gold strongly reflects yellow and red. Such semi-transparent sheets also strongly reflect infrared light, making them useful as infrared (radiant heat) shields in the visors of heat-resistant suits and in sun visors for spacesuits. Gold is a good conductor of heat and electricity. Gold has a density of 19.3 g/cm3, almost identical to that of tungsten at 19.25 g/cm3; as such, tungsten has been used in the counterfeiting of gold bars, such as by plating a tungsten bar with gold. By comparison, the density of lead is 11.34 g/cm3, and that of the densest element, osmium, is 22.588±0.015 g/cm3. ## Color Whereas most metals are gray or silvery white, gold is slightly reddish-yellow. This color is a well-known example of relativistic quantum chemistry. The 5d-6s band gap is greatly reduced when relativity is included in theoretical calculations, and this is thought to account for the yellow color, although a full comparison of the absorption spectrum between the relativistic and non-relativistic cases has not been performed as of 2004. Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are also important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, and both may be used to produce police and other badges. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, and purple gold can be made by alloying with aluminium. Less commonly, addition of manganese, indium, and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red if the particles are small; larger particles of colloidal gold are blue. ## Isotopes Gold has only one stable isotope, 197Au, which is also its only naturally occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205. The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au, which decays by proton emission with a half-life of 30 μs. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, and β+ decay. The exceptions are 195Au, which decays by electron capture, and 196Au, which decays most often by electron capture (93%) with a minor β− decay path (7%). All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have also been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, and 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric transition, and alpha decay. No other isomer or isotope of gold has three decay paths. ## Synthesis The possible production of gold from a more common element, such as lead, has long been a subject of human inquiry, and the ancient and medieval discipline of alchemy often focused on it; however, the transmutation of the chemical elements did not become possible until the understanding of nuclear physics in the 20th century. The first synthesis of gold was conducted by Japanese physicist Hantaro Nagaoka, who synthesized gold from mercury in 1924 by neutron bombardment. An American team, working without knowledge of Nagaoka's prior study, conducted the same experiment in 1941, achieving the same result and showing that the isotopes of gold produced by it were all radioactive. In 1980, Glenn Seaborg transmuted several thousand atoms of bismuth into gold at the Lawrence Berkeley Laboratory. Gold can be manufactured in a nuclear reactor, but doing so is highly impractical and would cost far more than the value of the gold that is produced. ## Chemistry Although gold is the most noble of the noble metals, it still forms many diverse compounds. The oxidation state of gold 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 with soft ligands such as thioethers, thiolates, and organophosphines. Au(I) compounds are typically linear. A good example is Au(CN)2−, which is the soluble form of gold encountered in mining. The binary gold halides, such as AuCl, form zigzag polymeric chains, again featuring linear coordination at Au. Most drugs based on gold are Au(I) derivatives. Au(III) (referred to as auric) is a common oxidation state, and is illustrated by gold(III) chloride, Au2Cl6. The gold atom centers in Au(III) complexes, like other d8 compounds, are typically square planar, with chemical bonds that have both covalent and ionic character. Gold(I,III) chloride is also known, an example of a mixed-valence complex. Gold does not react with oxygen at any temperature and, up to 100 °C, is resistant to attack from ozone: Au + O2 → (no reaction) Au + O3 \<100 °C→ (no reaction) Some free halogens react to form the corresponding gold halides. Gold is strongly attacked by fluorine at dull-red heat to form gold(III) fluoride AuF3. Powdered gold reacts with chlorine at 180 °C to form gold(III) chloride AuCl3. Gold reacts with bromine at 140 °C to form a combination of gold(III) bromide AuBr3 and gold(I) bromide AuBr, but reacts very slowly with iodine to form gold(I) iodide AuI: 2 Au + 3 F2 Δ→ 2 AuF3 2 Au + 3 Cl2 180 °C→ 2 AuCl3 2 Au + 2 Br2 140 °C→ AuBr3 + AuBr 2 Au + I2 Δ→ 2 AuI Gold does not react with sulfur directly, but gold(III) sulfide can be made by passing hydrogen sulfide through a dilute solution of gold(III) chloride or chlorauric acid. Unlike sulfur, phosphorus reacts directly with gold at elevated temperatures to produce gold phosphide (Au2P3). Gold readily dissolves in mercury at room temperature to form an amalgam, and forms alloys with many other metals at higher temperatures. These alloys can be produced to modify the hardness and other metallurgical properties, to control melting point or to create exotic colors. Gold is unaffected by most acids. It does not react with hydrofluoric, hydrochloric, hydrobromic, hydriodic, sulfuric, or nitric acid. It does react with selenic acid: 2 Au + 6 H2SeO4 200 °C→ Au2(SeO4)3 + 3 H2SeO3 + 3 H2O Gold is dissolved by aqua regia, a 1:3 mixture of nitric acid and hydrochloric acid. Nitric acid oxidizes the metal to +3 ions, but only in minute amounts, typically undetectable in the pure acid because of the chemical equilibrium of the reaction. However, the ions are removed from the equilibrium by hydrochloric acid, forming AuCl4− ions, or chloroauric acid, thereby enabling further oxidation: Au + 4 HCl + HNO3 → HAuCl4 + NO↑ + 2 H2O Gold is similarly unaffected by most bases. It does not react with aqueous, solid, or molten sodium or potassium hydroxide. It does, however, react with sodium or potassium cyanide under alkaline conditions when oxygen is present to form soluble complexes. Common oxidation states of gold include +1 (gold(I) or aurous compounds) and +3 (gold(III) or auric compounds). Gold ions in solution are readily reduced and precipitated as metal by adding any other metal as the reducing agent. The added metal is oxidized and dissolves, allowing the gold to be displaced from solution and be recovered as a solid precipitate. ## Rare oxidation states Less common oxidation states of gold include −1, +2, and +5. The −1 oxidation state occurs in aurides, compounds containing the Au− anion. Caesium auride (CsAu), for example, crystallizes in the caesium chloride motif; rubidium, potassium, and tetramethylammonium aurides are also known. Gold has the highest electron affinity of any metal, at 222.8 kJ/mol, making Au− a stable species, analogous to the halides. Gold also has a –1 oxidation state in covalent complexes with the group 4 transition metals, such as in titanium tetraauride and the analogous zirconium and hafnium compounds. These chemicals are expected to form gold-bridged dimers in a manner similar to titanium(IV) hydride. Gold(II) compounds are usually diamagnetic with Au–Au bonds such as \[Au(CH2)2P(C6H5)2\]2Cl2. The evaporation of a solution of Au(OH)3 in concentrated H2SO4 produces red crystals of gold(II) sulfate, Au2(SO4)2. Originally thought to be a mixed-valence compound, it has been shown to contain Au24+ cations, analogous to the better-known mercury(I) ion, Hg22+. A gold(II) complex, the tetraxenonogold(II) cation, which contains xenon as a ligand, occurs in \[AuXe4\](Sb2F11)2. In September 2023, a novel type of metal-halide perovskite material consisting of Au3+ and Au2+ cations in its crystal structure has been found. It has been shown to be unexpectedly stable at normal conditions. Gold pentafluoride, along with its derivative anion, AuF6−, and its difluorine complex, gold heptafluoride, is the sole example of gold(V), the highest verified oxidation state. Some gold compounds exhibit aurophilic bonding, which describes the tendency of gold ions to interact at distances that are too long to be a conventional Au–Au bond but shorter than van der Waals bonding. The interaction is estimated to be comparable in strength to that of a hydrogen bond. Well-defined cluster compounds are numerous. In some cases, gold has a fractional oxidation state. A representative example is the octahedral species \{Au(P(C6H5)3)\}62+. ## Gold production in the universe Gold in the universe is produced through several cosmic processes and was present in the dust from which the Solar System formed. Scientists have identified three main cosmic sources for gold formation: supernova nucleosynthesis, neutron star collisions, and magnetar flares. All three sources involve a process called the r-process (rapid neutron capture), which forms elements heavier than iron. For decades, scientists believed supernova nucleosynthesis was the primary mechanism for gold formation. More recently, research has shown that neutron star collisions produce significant quantities of gold through the r-process. In August 2017, the spectroscopic signatures of heavy elements, including gold, were directly observed by electromagnetic observatories during the GW170817 neutron star merger event. This confirmed neutron star mergers as a source of gold, after years of only indirect detection. This single event generated between 3 and 13 Earth masses of gold, suggesting that neutron star mergers might produce enough gold to account for most of this element in the universe. However, neutron star mergers alone cannot explain all cosmic gold, particularly in older stars, because these mergers occur relatively late in galactic history and are infrequent (approximately once every 100,000 years). This created a timing paradox in explaining the presence of gold in stars formed early in the universe. In 2025, researchers resolved this paradox by confirming that giant flares from magnetars (highly magnetic neutron stars) are also a significant source of gold formation. Analysis of a 2004 magnetar flare showed these events produce heavy elements through the same r-process as neutron star mergers. The amount of heavy elements created in a single magnetar flare can exceed the mass of Mars. Since magnetars existed earlier in cosmic history and flare more frequently than neutron star mergers occur, they help explain gold's presence in older stars. Scientists estimate magnetar flares may contribute approximately 1–10% of all elements heavier than iron in our galaxy, including gold. ## Asteroid origin theories Because the Earth was molten when it was formed, almost all of the gold present in the early Earth probably sank into the planetary core. Therefore, as hypothesized in one model, most of the gold in the Earth's crust and mantle is thought to have been delivered to Earth by asteroid impacts during the Late Heavy Bombardment, about 4 billion years ago. Gold which is reachable by humans has, in one case, been associated with a particular asteroid impact. The asteroid that formed Vredefort impact structure 2.020 billion years ago is often credited with seeding the Witwatersrand basin in South Africa with the richest gold deposits on earth. However, this scenario is now questioned. The gold-bearing Witwatersrand rocks were laid down between 700 and 950 million years before the Vredefort impact. These gold-bearing rocks had furthermore been covered by a thick layer of Ventersdorp lavas and the Transvaal Supergroup of rocks before the meteor struck, and thus the gold did not actually arrive in the asteroid/meteorite. What the Vredefort impact achieved, however, was to distort the Witwatersrand basin in such a way that the gold-bearing rocks were brought to the present erosion surface in Johannesburg, on the Witwatersrand, just inside the rim of the original 300 km (190 mi) diameter crater caused by the meteor strike. The discovery of the deposit in 1886 launched the Witwatersrand Gold Rush. Some 22% of all the gold that is ascertained to exist today on Earth has been extracted from these Witwatersrand rocks. ## Mantle return theories Much of the rest of the gold on Earth is thought to have been incorporated into the planet since its very beginning, as planetesimals formed the mantle. In 2017, an international group of scientists established that gold "came to the Earth's surface from the deepest regions of our planet", the mantle, as evidenced by their findings at Deseado Massif in the Argentinian Patagonia. ## Occurrence On Earth, gold is found in ores in rock formed from the Precambrian time onward. It most often occurs as a native metal, typically in a metal solid solution with silver (i.e. as a gold/silver alloy). Such alloys usually have a silver content of 8–10%. Electrum is elemental gold with more than 20% silver, and is commonly known as white gold. Electrum's color runs from golden-silvery to silvery, dependent upon the silver content. The more silver, the lower the specific gravity. Native gold occurs as very small to microscopic particles embedded in rock, often together with quartz or sulfide minerals such as "fool's gold", which is a pyrite. These are called lode deposits. The metal in a native state is also found in the form of free flakes, grains or larger nuggets that have been eroded from rocks and end up in alluvial deposits called placer deposits. Such free gold is always richer at the exposed surface of gold-bearing veins, owing to the oxidation of accompanying minerals followed by weathering; and by washing of the dust into streams and rivers, where it collects and can be welded by water action to form nuggets. Gold sometimes occurs combined with tellurium as the minerals calaverite, krennerite, nagyagite, petzite and sylvanite (see telluride minerals), and as the rare bismuthide maldonite (Au2Bi) and antimonide aurostibite (AuSb2). Gold also occurs in rare alloys with copper, lead, and mercury: the minerals auricupride (Cu3Au), novodneprite (AuPb3) and weishanite ((Au,Ag)3Hg2). A 2004 research paper suggests that microbes can sometimes play an important role in forming gold deposits, transporting and precipitating gold to form grains and nuggets that collect in alluvial deposits. A 2013 study has claimed water in faults vaporizes during an earthquake, depositing gold. When an earthquake strikes, it moves along a fault. Water often lubricates faults, filling in fractures and jogs. About 10 kilometers (6.2 mi) below the surface, under very high temperatures and pressures, the water carries high concentrations of carbon dioxide, silica, and gold. During an earthquake, the fault jog suddenly opens wider. The water inside the void instantly vaporizes, flashing to steam and forcing silica, which forms the mineral quartz, and gold out of the fluids and onto nearby surfaces. Gold can be found in M-type asteroids. ## Sources - Gold · Wikipedia: https://en.wikipedia.org/?curid=12240 Source: Wikipedia contributors — https://en.wikipedia.org/?curid=12240&oldid=1382173964 Licence: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation notice: Reformatted for XPay; the source may be abridged, restructured or translated. Consult the cited revision for the original.