79 platinum ← gold → mercury Ag ↑ Au ↓ Rg periodic table
General
Name, Symbol, Number	gold, Au, 79
Chemical series	transition metals
Group, Period, Block	11, 6, d
Appearance	metallic yellow
Atomic mass	196.96655(2) g/mol
Electron configuration	[Xe] 4f14 5d10 6s1
Electrons per shell	2, 8, 18, 32, 18, 1
Physical properties
Phase	solid
Density (near r.t.)	19.3 g/cm³
Liquid density at m.p.	17.31 g/cm³
Melting point	1337.33 K (1064.18 °C, 1947.52 °F)
Boiling point	3129 K (2856 °C, 5173 °F)
Heat of fusion	12.55 kJ/mol
Heat of vaporization	324 kJ/mol
Heat capacity	(25 °C) 25.418 J/(mol·K)
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 1646 1814 2021 2281 2620 3078
Atomic properties
Crystal structure	cubic face centered
Oxidation states	3, 1 (amphoteric oxide)
Electronegativity	2.54 (Pauling scale)
Ionization energies	1st: 890.1 kJ/mol
	2nd: 1980 kJ/mol
Atomic radius	135 pm
Atomic radius (calc.)	174 pm
Covalent radius	144 pm
Van der Waals radius	166 pm
Miscellaneous
Magnetic ordering	no data
Electrical resistivity	(20 °C) 22.14 nΩ·m
Thermal conductivity	(300 K) 318 W/(m·K)
Thermal expansion	(25 °C) 14.2 µm/(m·K)
Speed of sound (thin rod)	(r.t.) (hard-drawn) 2030 m/s
Young's modulus	78 GPa
Shear modulus	27 GPa
Bulk modulus	220 GPa
Poisson ratio	0.44
Mohs hardness	2.5
Vickers hardness	216 MPa
Brinell hardness	2450 MPa
CAS registry number	7440-57-5
Notable isotopes
Main article: Isotopes of gold iso NA half-life DM DE (MeV) DP 195Au syn 186.10 d ε 0.227 195Pt 196Au syn 6.183 d ε 1.506 196Pt β- 0.686 196Hg 197Au 100% Au is stable with 118 neutrons 198Au syn 2.69517 d β- 1.372 198Hg 199Au syn 3.169 d β- 0.453 199Hg
References

Gold is a chemical element in the periodic table that has the symbol Au (L. aurum) and atomic number 79. A soft, shiny, yellow, heavy, malleable, ductile (trivalent and univalent) transition metal, gold does not react with most chemicals but is attacked by chlorine, fluorine and aqua regia. The metal occurs as nuggets or grains in rocks and in alluvial deposits and is one of the coinage metals. General Name, Symbol, Number Platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10 , 6, d Density, Hardness 21450 kg/m³, 3. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... General Name, Symbol, Number silver, Ag, 47 Chemical series transition metals Group, Period, Block 11, 5, d Appearance lustrous white metal Atomic mass 107. ... General Name, Symbol, Number roentgenium, Rg, 111 Chemical series transition metals Group, Period, Block 11, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (272) g/mol Electron configuration probably [Rn] 5f14 6d10 7s1 Electrons per shell 2, 8, 18, 32, 32, 18, 1 Phase presumably a... big image: Image:Au-TableImage-BIG.png File links The following pages link to this file: Gold User:Femto/elements e9 Categories: GFDL images ... State at standard temperature and pressure those numbered in red are gases those numbered in green are liquids those numbered in black are solid Natural occurrence those without borders have not been discovered/synthesized yet those with dotted borders do not occur naturally (Synthetic elements) those with dashed borders naturally... This is a list of the chemical elements, sorted by name. ... Categories: Chemical elements ... A chemical series is a group of chemical elements whose physical and chemical characteristics vary progressively from one end of the series to another. ... This article is in need of attention. ... A periodic table group is a vertical column in the periodic table of the chemical elements. ... In the periodic table of the elements, a period is a row of the table. ... A block of the periodic table of elements is a set of adjacent groups. ... The Group 11 Elements (IB) of the periodic table consist of the traditional coinage metals of copper, silver, and gold. ... A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the Lanthanides. ... D Block is a rap group based in Yonkers, New York. ... Color is an important part of the visual arts. ... Gold sample. ... ... To help compare different orders of magnitude we list here masses between 60. ... Electron atomic and molecular orbitals In atomic physics, the electron configuration is the arrangement of electrons in an atom, molecule or other body. ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Atomic mass 131. ... Properties The electron is a subatomic particle. ... In physics and quantum chemistry, an energy level is a quantized energy of a bound quantum mechanical state. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... A solid is a state of matter, characterized by a definite volume and a definite shape (i. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... Room temperature, in laboratory reports, is taken to be roughly 21–23 degrees Celsius (70–73 degrees Fahrenheit), or 294–296 kelvins. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ... Fahrenheit is a temperature scale named after the German physicist Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... The boiling point of a substance is the temperature at which it can change state from a liquid to a gas throughout the bulk of the liquid. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... The degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701–1744), who first proposed a similar system in 1742. ... Fahrenheit is a temperature scale named after the German physicist Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... This article is in need of attention. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... The heat of vaporization is a physical property of substances. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... Heat capacity (abbreviated Cth or just C, also called thermal capacity) is the ability of matter to store heat. ... The vapor pressure is the pressure (if the vapor is mixed with other gases, the partial pressure) of a vapor. ... Rose des Sables (Sand Rose), a formation of gypse crystal In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The oxidation state or oxidation number is defined as the sum of negative and positive charges in an atom, which indirectly indicates the number of electrons it has accepted or donated. ... In chemistry, an amphoteric substance is one that can react with either an acid or base (more generally, the word describes something made of, or acting like, two components). ... Electronegativity is the measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... Electronegativity is a measure of the attraction that an atom has for the bonding pair of electrons in a covalent bond. ... ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... The poopie is the distance from the atomic nucleus to the outmost stable electron orbital in a atom that is at equilibrium. ... To help compare different orders of magnitude this page lists lengths between 100 pm and 1 nm (10-10 m and 10-9 m). ... Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... The poopie is the distance from the atomic nucleus to the outmost stable electron orbital in a atom that is at equilibrium. ... To help compare different orders of magnitude this page lists lengths between 100 pm and 1 nm (10-10 m and 10-9 m). ... Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... Covalent radius in chemistry corresponds to half of the distance between two identical atomic nuclei, bound by a covalent bond. ... To help compare different orders of magnitude this page lists lengths between 100 pm and 1 nm (10-10 m and 10-9 m). ... Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... The title given to this article is incorrect due to technical limitations. ... To help compare different orders of magnitude this page lists lengths between 100 pm and 1 nm (10-10 m and 10-9 m). ... Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. ... // Headline text POOP!! Danny Hornsby (also known as Gnome) is a measure indicating how strongly a Gnome can opposes the flow of electric current. ... It is the quantity of heat, Q, transmitted through a unit thickness, L, in a direction normal to a surface of unit area, A, due to a unit temperature gradient, ΔT, under steady state conditions and when the heat transfer is dependent only on the temperature gradient. ... In physics, thermal conductivity, λ, is the quantity of heat transmitted, due to unit temperature gradient, in unit time under steady conditions in a direction normal to a surface of unit area, when the heat transfer is dependent only on the temperature gradient thermal conductivity = heat flow rate / (distance × temperature... The coefficient of thermal expansion is used in two ways: as a volumetric thermal expansion coefficient as a linear thermal expansion coefficient These characteristics are closely related. ... The speed of sound c (from Latin celeritas, velocity) varies depending on the medium through which the sound waves pass. ... Room temperature, in laboratory reports, is taken to be roughly 21–23 degrees Celsius (70–73 degrees Fahrenheit), or 294–296 kelvins. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... In solid mechanics, Youngs modulus (also known as the modulus of elasticity or elastic modulus) is a measure of the stiffness of a given material. ... In materials science, shear modulus S, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain: S = shear stress/shear strain = (F/A)/Φ. Another commonly accepted symbol is G. Shear modulus is usually measured in ksi (kips per square... The bulk modulus K of a fluid or solid is the inverse of the compressibility: where p is pressure and V is volume. ... When a sample of material is stretched in one direction, it tends to get thinner in the other two directions. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... The Vickers hardness test was developed in the early 1920s and uses a pyramid-shaped indenter made of diamond. ... The Brinell scale characterises the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Isotopes are forms of a chemical element whose nuclei have the same atomic number, Z, but different atomic masses, A. The word isotope, meaning at the same place, comes from the fact that all isotopes of an element are located at the same place on the periodic table. ... Natural abundance refers to the prevalence of different isotopes of an element as found in nature. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... In physics, the decay mode describes a particular way a particle decays. ... The decay energy is the energy released by a nuclear decay. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... A Synthetic radioisotope is a radioisotope that is not found in nature no matter by what mechanism it is formed. ... Electron capture is a decay mode for chemical elements that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron. ... General Name, Symbol, Number Platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10 , 6, d Density, Hardness 21450 kg/m³, 3. ... A Synthetic radioisotope is a radioisotope that is not found in nature no matter by what mechanism it is formed. ... Electron capture is a decay mode for chemical elements that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron. ... General Name, Symbol, Number Platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10 , 6, d Density, Hardness 21450 kg/m³, 3. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... Different isotopes of one chemical element may have different radioactive properties. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... A Synthetic radioisotope is a radioisotope that is not found in nature no matter by what mechanism it is formed. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... A Synthetic radioisotope is a radioisotope that is not found in nature no matter by what mechanism it is formed. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery white Atomic mass 200. ... Recommended values for many properties of the elements, together with various references, are collected on these data pages. ... A chemical element, often called simply element, is a substance that cannot be divided or changed into different substances by ordinary chemical methods. ... The periodic table of the chemical elements, also called the Mendeleev periodic table, is a tabular display of the known chemical elements. ... Latin is the language originally spoken in the region around Rome called Latium. ... The atomic number (Z) is a term used in chemistry and physics to represent the number of protons found in the nucleus of an atom. ... This article is in need of attention. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Atomic mass 35. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ... Aqua regia (Latin for royal water) is a highly corrosive, fuming yellow liquid, formed by a fresh mixture of concentrated nitric acid (otherwise known as aqua fortis) and concentrated hydrochloric acid, usually in the ratio of one to three. ... Categories: Substubs ... An alluvial deposit is an accumulation of alluvium (sediment), sometimes containing valuable ore and gemstones, or simply consisting of gravel, sand, or clay, in the bed or former bed of a river. ... The Group 11 Elements (IB) of the periodic table consist of the traditional coinage metals of copper, silver, and gold. ...

Gold is used as a monetary standard for many nations and is also used in jewelry, dentistry, and in electronics. Its ISO currency code is XAU. 1922 U.S. gold certificate The gold standard is a monetary system in which the standard economic unit of account is a fixed weight of gold. ... Jewelry (spelled jewellery in British English) consists of ornamental devices worn by persons, typically made with gems and precious metals. ... X-rays can reveal if a person has cavities Dentistry is the practical application of knowledge of dental science (the science of placement, arrangement, function of teeth and their supporting bones and soft tissues) to human beings. ... Two digital voltmeters The field of electronics is the study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. ... ISO 4217 is an international standard describing three letter codes to define the names of currencies established by the International Organization for Standardization (ISO). ...

Notable characteristics

Gold is a metallic element with a characteristic yellow color, but can also be black or ruby when finely divided, while colloidal solutions are intensely colored and often purple. These colors are the result of gold's plasmon frequency lying in the visible range, which causes red and yellow light to be reflected and blue light to be absorbed. It is one of only three metals which have an actual easily-identifiable color; the other two are copper, which is red, and caesium, which has a gold color. Yellow is the color of light whose wavelength is between 565 nm and 590 nm. ... Black is a color with several subtle differences in meaning. ... Ruby is a red gemstone, a variety of the mineral corundum in which the color is caused mainly by chromium. ... In general, a colloid or colloidal dispersion, is a two-phase system of matter; a type of mixture intermediate between homogeneous mixtures and heterogeneous mixtures. ... Chromaticity diagram - lower right straight border is the line of purple Purple is any of a group of colors intermediate between blue and red. ... In physics, the plasmon is the particle resulting from the quantization of plasma oscillations, which are density waves of the charge carriers in a conducting medium such as a metal, semiconductor, or plasma. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance copper, metallic Atomic mass 63. ... General Name, Symbol, Number caesium, Cs, 55 Chemical series alkali metals Group, Period, Block 1, 6, s Appearance silvery gold Atomic mass 132. ...

It is the most malleable and ductile metal known; a single gram can be beaten into a sheet of one square meter, or an ounce into 300 square feet. A soft metal, gold will readily form alloys with many other metals. This can be done to increase its strength, or create several exotic colors, sold for instance in the western United States to the tourist trade as "Black Hills" gold. Adding copper yields a redder metal, iron green, aluminium purple, platinum metals white, and natural bismuth together with silver alloys produce black. Native gold contains usually eight to ten per cent silver, but often much more — alloys with a silver content over 20% are called electrum. As the amount of silver increases, the color becomes whiter and the specific gravity lower. Malleability is a physical property of matter, signifying its capability of deformation, especially by hammering or rolling. ... Ductility is the physical property of being capable of sustaining large plastic deformations without fracture (in metals, such as being drawn into a wire). ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms ions (cations) and has metallic bonds, and metals are sometimes described as a lattice of positive ions (cations) in a cloud of electrons. ... The gram or gramme, symbol g, is a unit of mass, and is defined in the SI system of units as one one-thousandth of a kilogram (i. ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ... The ounce is the name for a number of different units of mass (oz), and also of two units of fluid volume (fl oz) and of one unit of force, the ounce-force (ozf). ... A square foot is by definition the area enclosed by a square with sides each 1 foot long. ... The Black Hills are a small, isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance copper, metallic Atomic mass 63. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number Platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10 , 6, d Density, Hardness 21450 kg/m³, 3. ... General Name, Symbol, Number Bismuth, Bi, 83 Chemical series Poor metals Group, Period, Block 15 (VA), 6, p Density, Hardness 9. ... General Name, Symbol, Number silver, Ag, 47 Chemical series transition metals Group, Period, Block 11, 5, d Appearance lustrous white metal Atomic mass 107. ... Electrum coin of the Byzantine Emperor Alexius I Comnenus. ... Relative density (also known as specific gravity) is a measure of the density of a material. ...

Gold is a good conductor of heat and electricity, and is not affected by air and most reagents. Heat, moisture, oxygen, and most corrosive agents have very little chemical effect on gold, making it well-suited for use in coins and jewelry; conversely, halogens will chemically alter gold, and aqua regia dissolves it. A red-hot iron rod cooling after being worked by a blacksmith. ... Lightning strikes during a night-time thunderstorm. ... Air is a name for the mixture of gases present in the Earths atmosphere. ... A reagent is any substance used in a chemical reaction. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Corrosion Corrosion is deterioration of useful properties in a material due to reactions with its environment. ... 1¢ euro coin A coin is usually a piece of hard material, generally metal and usually in the shape of a disc, which is used as a form of money. ... Jewelry (spelled jewellery in British English) consists of ornamental devices worn by persons, typically made with gems and precious metals. ... The halogens are a chemical series. ... Aqua regia (Latin for royal water) is a highly corrosive, fuming yellow liquid, formed by a fresh mixture of concentrated nitric acid (otherwise known as aqua fortis) and concentrated hydrochloric acid, usually in the ratio of one to three. ...

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 out as gold metal by the addition of virtually 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. The oxidation state or oxidation number is defined as the sum of negative and positive charges in an atom, which indirectly indicates the number of electrons it has accepted or donated. ... The most fundamental reactions in chemistry are the redox processes. ... The most fundamental reactions in chemistry are the redox processes. ...

Recent research undertaken by Frank Reith of the Australian National University shows that microbes play an important role in the formation of gold deposits, transporting and precipitating gold to form grains and nuggets that collect in alluvial deposits. [1]

Applications

Pure gold is too soft for ordinary use and is hardened by alloying with silver, copper, and other metals. Gold and its many alloys are most often used in jewelry, coinage and as a standard for monetary exchange in many countries. Because of its high electrical conductivity and resistance to corrosion and other desirable combinations of physical and chemical properties, gold also emerged in the late 20th century as an essential industrial metal. An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resultant material has metallic properties. ... Jewelry (spelled jewellery in British English) consists of ornamental devices worn by persons, typically made with gems and precious metals. ... 1¢ euro coin A coin is usually a piece of hard material, generally metal and usually in the shape of a disc, which is used as a form of money. ... Money is any marketable good or token used by a society as a store of value, a medium of exchange, or a unit of account. ... (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the...

Other uses:

• Gold can be made into thread and used in embroidery.
• Gold performs critical functions in computers, communications equipment, spacecraft, jet aircraft engines, and a host of other products.
• The resistance to oxidation of gold has led to its widespread use as thin layers electroplated on the surface of electrical connectors to ensure a good connection.
• Gold is used in restorative dentistry especially in tooth restorations such as crowns and bridges.
• Colloidal gold (a gold nanoparticle) is an intensely colored solution that is currently studied in many labs for medical, biological and other applications. It is also the form used as gold paint on ceramics prior to firing.
• Chlorauric acid is used in photography for toning the silver image.
• Gold(III) chloride is used as a catalyst in organic chemistry. It is also the usual starting point for making other gold compounds.
• Disodium aurothiomalate is a treatment for rheumatoid arthritis (administered intramuscularly). It inhibits lymphocyte proliferation, lysosomal enzyme release, the release of reactive oxygen species from macrophages, and IL-1 production. However, it can also cause photosensitive rashes, gastrointestinal disturbance, and kidney damage.
• The gold isotope Au-198, (half-life: 2.7 days) is used in some cancer treatments and for treating other diseases.
• Gold is used as a coating enabling biological material to be viewed under a scanning electron microscope.
• Many competitions and honors, such as the Olympics and the Nobel Prize, award a gold medal to the winner (with silver to the second-place finisher, and bronze to the third.)
• Since it is a good reflector of both infrared and visible light, it is used for the protective coatings on many artificial satellites.
• Gold flake is used on and in some gourmet sweets and drinks. Having no reactivity it adds no taste but is taken as a delicacy.
• White gold (an alloy of gold with platinum, palladium, nickel, and/or zinc) serves as a substitute for platinum.
• Green gold (a gold/silver alloy) is used in specialized jewelry while gold alloys with copper (reddish color) are more widely used for that purpose.

Gold Embroidery Embroidery is an ancient variety of decorative needlework in which designs and pictures are created by stitching strands of some material on to a layer of another material. ... A computer is a device or machine for making calculations or controlling operations that are expressible in numerical or logical terms. ... Ariane 5 lifts off with the Rosetta probe on 2nd of March, 2004. ... Jet aircraft are aircraft with jet engines. ... Electroplating is the coating of an electrically conductive item with a layer of metal using electrical current. ... A crown (sometimes incorrectly called a cap) is a tooth form produced by a dental technician. ... This article is about the edifice. ... Colloidal gold, or more precisely gold nanoparticles are sub-micrometre sized particles of gold, usually found in the form of a suspension in water (hence colloid), in which case the liquid usually appears to be either an intense red colour (for particles less than 100 nm), or a dirty yellowish... Very Basic Description A nanoparticle is a microscopic particle whose size is measured in nanometers. ... Color is an important part of the visual arts. ... The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. ... Gold(III) chloride, traditionally called auric chloride, is one of the most common compounds of gold. ... Lens and mounting of a large format camera Photography is the process of making pictures by means of the action of light. ... Gold(III) chloride, traditionally called auric chloride, is one of the most common compounds of gold. ... A catalyst (Greek: καταλύτης, catalytis) is a substance that accelerates the rate of a chemical reaction, at some temperature, but without itself being transformed or consumed by the reaction (see also catalysis). ... Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds. ... An inorganic compound is a chemical compound not containing carbon and hydrogen atoms bonded to each other. ... Arthritis (from Greek arthro-, joint + -itis, inflammation) is a group of conditions that affect the health of the bone joints in the body. ... A lymphocyte is a type of white blood cell involved in the human bodys immune system. ... Lysosomes are organelles in animal cells that contain digestive enzymes (acid hydrolases) to digest macromolecules. ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ... Macrophages (Greek: big eaters) are cells found in tissues that are responsible for phagocytosis of pathogens, dead cells and cellular debris. ... Interleukin-1 (IL-1) is secreted by the macrophages, monocytes and dendritic cells. ... For the manga by Tsukasa Hôjô, see Rash. ... Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Low temperature SEM magnification series for a snow crystal. ... For months before the Olympic Games, runners relay the Olympic Flame from Olympia to the opening ceremony. ... Photographs of Nobel Prize Medals. ... A Medal can mean three things: a wearable medal awarded by a government for services to a country (such as Armed force service); strictly speaking this only refers to a medal of coin-like appearance, but informally the word also refers to an Order (decoration); a table medal awarded by... General Name, Symbol, Number silver, Ag, 47 Chemical series transition metals Group, Period, Block 11, 5, d Appearance lustrous white metal Atomic mass 107. ... Bronze figurine, found at Öland Bronze is the traditional name for a broad range of alloys of copper. ... A satellite is an object that orbits another object (known as its primary). ... White gold refers to an alloy of gold and other white metals such as silver, palladium, or nickel. ... General Name, Symbol, Number Platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10 , 6, d Density, Hardness 21450 kg/m³, 3. ... This article describes the chemical element palladium. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic Atomic mass 58. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Atomic mass 65. ... General Name, Symbol, Number silver, Ag, 47 Chemical series transition metals Group, Period, Block 11, 5, d Appearance lustrous white metal Atomic mass 107. ...

History

A gold nugget

Gold (Sanskrit jval, Greek χρυσος [khrusos], Latin aurum for "shining dawn", Anglo-Saxon gold, Chinese 金 [jīn]) has been known and highly valued since prehistoric times. It may have been the first metal used by humans and was valued for ornamentation and rituals. Egyptian hieroglyphs from as early as 2600 BC describe gold, whose king Tushratta of the Mitanni claimed was as "common as dust" in Egypt. Egypt and Nubia had the resources to make them major gold-producing areas for much of history. Gold is also mentioned several times in the Old Testament. The south-east corner of the Black Sea was famed for its gold. Exploitation is said to date from the time of Midas, and this gold was important in the establishment of what is probably the world's earliest coinage in Lydia between 643 and 630 BC. Commons:Image:GoldNuggetUSGOV.jpg File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Commons:Image:GoldNuggetUSGOV.jpg File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The Sanskrit language ( संस्कृता वाक्) is one of the earliest attested members of the Indo-European language family and is not only a classical language, but also an official language of India. ... Latin is the language originally spoken in the region around Rome called Latium. ... Note: This page contains phonetic information presented in the International Phonetic Alphabet (IPA) using Unicode. ... Binomial name Homo sapiens Linnaeus, 1758 Subspecies Homo sapiens idaltu (extinct) Homo sapiens sapiens Human beings define themselves in biological, social, and spiritual terms. ... Hieroglyphs are a system of writing used by the Ancient Egyptians, using a combination of logographic, syllabic, and alphabetic elements. ... (Redirected from 2600 BC) (27th century BC - 26th century BC - 25th century BC - other centuries) (4th millennium BC - 3rd millennium BC - 2nd millennium BC) Events 2900 - 2334 BC – Mesopotamian wars of the Early Dynastic period. ... Tushratta was a king of the Mitanni at the end of the reign of Amenhotep III and throughout the reign of Akhenaten -- approximately the late 14th century BC. He was the son of Shuttarna II, and his daughter Tadukhipa was married to Akhenaten. ... Mitanni or Mittani (in Assyrian sources Hanilgalbat, Khanigalbat) was a kingdom in northern Syria. ... Today Nubia is the region in the south of Egypt, along the Nile and in northern Sudan, but in ancient times it was an independent kingdom. ... The Old Testament or the Hebrew Scriptures (also called the Hebrew Bible) constitutes the first major part of the Bible according to Christianity. ... Satellite view of the Black Sea, taken by NASA MODIS Cities of the Black Sea The Black Sea (known as the Euxine Sea in antiquity) is an inland sea between southeastern Europe and Asia Minor. ... Midas was a character in Greek mythology, who is most recognized for his ability to turn anything he touched into gold. ... Lydia was an ancient kingdom of Asia Minor, known to Homer as Mæonia. ... Centuries: 8th century BC - 7th century BC - 6th century BC Decades: 680s BC 670s BC 660s BC 650s BC 640s BC - 630s BC - 620s BC 610s BC 600s BC 590s BC 580s BC Events and Trends 637 BC - Josiah becomes king of Judah. ...

The European exploration of the Americas was fueled in no small part by reports of the gold ornaments displayed in great profusion by Native American peoples, especially in Central America, Peru, and Colombia. Native Americans (also Indians, Aboriginal Peoples, American Indians, First Nations, Alaskan Natives, Amerindians, or Indigenous Peoples of America) are the indigenous inhabitants of The Americas prior to the European colonization, and their modern descendants. ... Central America is the region of North America located between the southern border of Mexico and the northwest border of Colombia, in South America. ...

Gold has long been considered one of the most precious metals, and its value has been used as the standard for many currencies (known as the gold standard) in history. Gold has been used as a symbol for purity, value, royalty, and particularly roles that combine these properties (see gold album). A precious metal is a rare metallic element of high, durable economic value. ... 1922 U.S. gold certificate The gold standard is a monetary system in which the standard economic unit of account is a fixed weight of gold. ... The description Gold Album is applied to recorded music albums that have sold a minimum number of copies (in the US, currently 500,000 sales). ...

Gold in antiquity was relatively easy to obtain geologically; however, 75% of all gold ever produced has been extracted since 1910.[2] It has been estimated that all the gold in the world that has ever been refined would form a single cube 20 m (66 ft) a side. 1910 was a common year starting on Saturday (see link for calendar). ... To help compare different orders of magnitude this page lists lengths between 100 m and 1 km. ...

The primary goal of the alchemists was to produce gold from other substances, such as lead — presumably by the interaction with a mythical substance called the philosopher's stone. Although they never succeeded in this attempt, the alchemists promoted an interest in what can be done with substances, and this laid a foundation for today's chemistry. Their symbol for gold was the circle with a point at its center (☉), which was also the astrological symbol, the Egyptian hieroglyph and the ancient Chinese character for the Sun (now 日). For modern attempts to produce artificial gold, see gold synthesis. Circumpunct. ... Alchemy is an early protoscientific practice combining elements of chemistry, physics, astrology, art, semiotics, metallurgy, medicine, mysticism, and religion. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... The philosophers stone, a longtime Holy Grail of Western alchemy, is a mythical substance that supposedly could turn inexpensive metals into gold and/or create an elixir that would make humans immortal. ... Chemistry (in Greek: χημεία) is the science of matter and its interactions with energy and itself (see physics, biology). ... The circle with a point at the centre (☉) is a symbol featuring a circle with the middle marked with a dot. ... An astrological chart (or horoscope) - Y2K Chart — This particular chart is calculated for January 1, 2000 at 12:01:00 A.M. Eastern Standard Time in New York City, New York, USA. (Longitude: 074W0023 - Latitude: 40N4251), using the tropical zodiac Astrology (from Greek: αστρολογία = άστρον, astron, star + λόγος, logos, word) is... Hieroglyphs are a system of writing used by the Ancient Egyptians, using a combination of logographic, syllabic, and alphabetic elements. ... 漢字 hànzì, kanji… in Traditional Chinese and other languages. ... A sun is the star at the center of a planetary system. ... As Gold synthesis one understands the age-old dream of the Alchemists, the production of gold. ...

During the 19th century gold rushes occurred whenever large gold deposits were discovered, including the California, Colorado, Otago, Australia, Witwatersrand, Black Hills, and Klondike gold rushes. Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... Gold rush ad A gold rush is a period of feverish migration of workers into the area of a dramatic discovery of commercial quantities of gold. ... Gold rush handbill The California Gold Rush was a period in American history marked by mass hysteria concerning a gold discovery in Northern California. ... The Colorado Gold Rush was the boom in the prospecting and mining of gold in present-day Colorado in the United States that began in 1859 and lasted throughout the early 1860s. ... The Central Otago Goldrush (often simply called the Otago goldrush) occurred during the 1860s in Otago, New Zealand. ... Witwatersrand is a low mountain range which runs through Gauteng in South Africa. ... The Black Hills are a small, isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming. ... The Klondike is a region of the Yukon Territory in northwest Canada, just east of the Alaska border. ...

Because of its historically high value, much of the gold mined throughout history is still in circulation in one form or another.

Value

Gold ingots, like these from the Bank of Sweden, form the base of many monetary systems.

Like other precious metals, gold is measured by troy weight and by grams. When it is alloyed with other metals the term carat or karat is used to indicate the amount of gold present, with 24 carats being pure gold and lower ratings proportionally less. The purity of a gold bar can also be expressed as a decimal figure ranging from 0 to 1, known as the millesimal fineness, such as 0.995. Commons:Image:Gold ingots. ... Commons:Image:Gold ingots. ... Sveriges Riksbank is the central bank of Sweden, sometimes called just the Bank of Sweden. ... Troy weight is a system of units of mass customarily used for precious metals and gemstones. ... The gram or gramme, symbol g, is a unit of mass, and is defined in the SI system of units as one one-thousandth of a kilogram (i. ... For other meanings, see Carat. ... Millesimal fineness is a system of denoting the purity of platinum, gold and silver alloys by parts per thousand of pure metal in the alloy. ...

The price of gold is determined on the open market, but a procedure known as the Gold Fixing in London, originating in 1919, provides a twice-daily benchmark figure to the industry. The Gold Fixing or Gold Fix is the procedure by which the price of gold is set on the London market by the five members of the London gold pool. ... St. ...

Historically gold was used to back currency in an economic system known as the gold standard in which one unit of currency was equivalent to a certain weight of gold. As part of this system, governments and central banks attempted to control the price of gold by setting values at which they would exchange it for currency. For a long period the United States government set the price of gold at $20.67 per troy ounce ($664.56/kg) but in 1934 the price of gold was set at $35.00 per troy ounce ($1125.27/kg). By 1961 it was becoming hard to maintain this price, and a pool of US and European banks began to act together to defend the price against market forces. 1922 U.S. gold certificate The gold standard is a monetary system in which the standard economic unit of account is a fixed weight of gold. ... Weight is the force exerted upon an object by virtue of its position in a gravitational field. ... Troy weight is a system of units of mass customarily used for precious metals and gemstones. ... 1934 was a common year starting on Monday (link will take you to calendar). ...

On March 17, 1968, economic circumstances caused the collapse of the gold pool, and a two-tiered pricing scheme was established whereby gold was still used to settle international accounts at the old $35.00 per troy ounce ($1.13/g) but the price of gold on the private market was allowed to fluctuate; this two-tiered pricing system was abandoned in 1975 when the price of gold was left to find its free-market level. Central banks still hold historical gold reserves as a reserve asset although the level has generally been declining. The largest gold depository in the world is the U.S. Federal Reserve Bank of New York. March 17 is the 76th day of the year in the Gregorian Calendar (77th in Leap years). ... 1968 was a leap year starting on Monday (the link is to a full 1968 calendar). ... Official gold reserves Gold reserves or gold holdings are held by central banks as a store of value generally to be used as a last resort. ... Reserves are banks holding of deposits in accounts with their national bank (for instance, the Federal Reserve), plus currency that is physically held by banks (vault cash). ... The Federal Reserve System is headquartered in the Eccles Building on Constitution Avenue in Washington, DC. The Federal Reserve System (also the Federal Reserve; informally The Fed) is the central bank of the United States. ...

Since 1968 the price of gold on the open market has ranged widely, with a record high of $850/oz ($27,300/kg) on 21 January 1980, to a low of $252.90/oz ($8,131/kg) on 21 June 1999 (London Fixing). Prices have risen to the $420/oz ($13,500/kg) mark in 2004, due to a depreciation of the US dollar (an inverse relation between the prices exists to a certain extent). The price of gold has remained relatively constant in currencies not tied to the US dollar; for example, it has not varied by more than 10% from €330/oz (€10,600/kg) or A$560/oz (A$18,000/kg) during this time. January 21 is the 21st day of the year in the Gregorian Calendar. ... 1980 is a leap year starting on Tuesday. ... June 21 is the 172nd day of the year (173rd in leap years) in the Gregorian calendar, with 193 days remaining. ... 1999 is a common year starting on Friday of the Common Era, and was designated the International Year of Older Persons by the United Nations. ... The euro (€; ISO 4217 code EUR) is the currency of twelve European Union member states: Austria, Belgium, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal, and Spain. ... Australian one-hundred dollar note The Australian dollar, AUD or A$, is the official currency of the Commonwealth of Australia, including the Australian Antarctic Territory, Christmas Island, Cocos (Keeling) Islands, Heard Island and McDonald Islands and Norfolk Island, as well as the independent Pacific island states of Kiribati, Nauru and...

Because of its use as a reserve store of value, the possession of gold is sometimes restricted or banned. Within the United States, the private possession of gold except as jewelry and coin collecting was banned between 1933 and 1975. President Franklin D. Roosevelt confiscated gold by Executive Order 6102, and President Richard Nixon closed the gold window by which foreign countries could exchange American dollars for gold at a fixed rate. Order: 32nd President Vice President: John N. Garner Henry A. Wallace Harry S. Truman Term of office: March 4, 1933 – April 12, 1945 Preceded by: Herbert Hoover Succeeded by: Harry S. Truman Date of birth: January 30, 1882 Place of birth: Hyde Park, New York Date of death: April 12... Order: 37th President Vice President: Spiro Agnew (1969–1973), Gerald R. Ford (1973–1974) Term of office: January 20, 1969 – August 9, 1974 Preceded by: Lyndon B. Johnson Succeeded by: Gerald R. Ford Date of birth: January 9, 1913 Place of birth: Yorba Linda, California Date of death: April 22...

In the first few years of the 21st century, reports started to circulate that Malaysia was planning a return to the gold standard -- to issue and use gold dinars as currency in international trade. The purported purpose of this move would be to reduce dependence on the United States dollar as a reserve currency, and to establish a non-debt-backed currency in accord with Islamic law against the charging of interest. [3] Nonetheless, gold dinar currency has not yet emerged. [4] [5] (20th century - 21st century - 22nd century - other centuries) Decades: 2000s 2010s 2020s 2030s 2040s 2050s 2060s 2070s 2080s 2090s In calendars based on the Christian Era or Common Era, such as the Gregorian calendar, the 21st century is the current century, as of this writing. ... 1922 U.S. gold certificate The gold standard is a monetary system in which the standard economic unit of account is a fixed weight of gold. ... A five-dinar note featuring Saddam Hussein The word Dinar (in Arabic and Persian: دينار) traces its origin back to the Roman currency, the denarius (pl. ... The United States dollar, or American dollar, is the official currency of the United States. ... Sharia (Arabic شريعة also Sharia, Shariah or Syariah) is traditional Islamic law. ...

As a tangible investment gold is sometimes held as part of a portfolio because over the long term gold has an extensive history of maintaining its value. It has in the last century gained ground in relation to fiat currencies owing to inflation. Speculating in gold, attempting to buy low and sell high, carries large transaction costs. However, gold does become particularly desirable in times of extremely weak confidence and during hyperinflation because gold maintains its value even as fiat money becomes worthless. People who, despite the risks, enjoy investing in gold are known as goldbugs. In contrast to stocks, bonds, and real estate (see equity investment , real estate investment), tangible investments are objects; there is a wide variety, including: Art Precious metals and Gems Collectibles, such as: Postage stamps (see stamp collecting, philatelic investment) Coins (see coin collecting) Autographs and historic documents Memorabilia, such as... A 1,000,000,000 (1 billion) Mark banknote, issued in Bavaria/Germany during the hyperinflation of 1923 (http://www. ... Fiat money or fiat currency, usually paper money, is a type of currency whose only value is that a government made a fiat (i. ... The term goldbug is used to describe investors who are very bullish on buying the commodity gold. ...

Futures contracts based on gold currently trade on various exchanges around the world. In the US this occurs primarily on COMEX (Commodity Exchange) which is a subsidiary of the New York Mercantile Exchange. Speculation about the future price of gold and other commodities is carried on at COMEX. A futures contract is a form of forward contract, a contract to buy or sell an asset of any kind at a pre-agreed future point in time, that has been standardised for a wide range of uses. ... The New York Mercantile Exchange (NYMEX) is the worlds largest physical commodity futures exchange located in New York City. ...

Occurrence

Native gold from California (top) and Australia (bottom), showing octahedral formations

Due to its relative chemical inertness gold is usually found as the native metal or alloy. Occasionally large accumulations of native gold (also known as nuggets) occur but usually gold occurs as minute grains. These grains occur between mineral grain boundries or as inclusions within minerals. Common gold associations are quartz often as veins and sulfide minerals. The most common sulfide associations are pyrite, chalcopyrite, galena, sphalerite, arsenopyrite, stibnite and pyrrhotite. Rarer mineral associations are petzite, calaverite, sylvanite, muthmannite, nagyagite and krennerite. File links The following pages link to this file: Gold User:Aramgutang/Gallery Categories: User-created public domain images ... File links The following pages link to this file: Gold User:Aramgutang/Gallery Categories: User-created public domain images ... An octahedron (plural: octahedra) is a polyhedron with eight faces. ... Categories: Substubs ... Quartz is the second most abundant mineral in the Earths crust. ... In biology, a vein is a blood vessel which returns blood from the microvasculature to the heart. ... The mineral pyrite, or iron pyrite, is iron disulfide, FeS2. ... Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. ... Galena is a lead ore. ... Sphalerite sample Another sphalerite sample Sphalerite (ZnS) is a mineral that is the chief ore of zinc. ... Arsenopyrite is an iron arsenic sulfide (FeAsS). ... Stibnite, sometimes also called antimonite, is a sulfide mineral. ... Pyrrhotite is an unusual iron sulfide mineral with a variable iron content: Fe(1-x)S (x = 0 to 0. ... The mineral petzite, Ag3AuTe2, is a soft, steel-gray mineral generally deposited by hydrothermal activity. ... Calaverite or Gold telluride is an uncommon telluride of gold; it is a metallic mineral. ... Sylvanite or Silver gold telluride, (Ag,Au)Te2, is the most common telluride of gold. ... Krennerite is an orthorhombic gold telluride mineral which can contain a relatively small amount of silver in the structure. ...

Gold is widely distributed in the earth's crust at a background level of 0.03 g/1000 kg (0.03 ppm). Hydrothermal ore deposits of gold occur in metamorphic rocks and igneous rocks; alluvial deposits and placer deposits originate from these sources. In geology, a crust is the outer layer of a planet, part of its lithosphere. ... The gram or gramme, symbol g, is a unit of mass, and is defined in the SI system of units as one one-thousandth of a kilogram (i. ... KG, Kg or kg may indicate: A Kampfgeschwader, a bomber squadron of the former German Luftwaffe Basketball Player Kevin Garnett An abbreviation for kilogram (always kg) Knight of the Garter, a British decoration Kongo language (ISO 639 alpha-2) An abbreviation for konig or king Kwansei Gakuin University (Japan) [1... Parts per million (ppm) is a measure of concentration that is used where low levels of concentration are significant. ... Hydrothermal circulation in the oceans is the passage of the water through mid-ocean Ridge (MOR) systems. ... An ore is a mineral deposit containing a metal or other valuable resource in economically viable concentrations. ... Metamorphic rock is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means change in form (from the Greek words meta, change, and morphe, form). The protolith is subjected to extreme heat (greater than 150 degrees Celsius) and pressure causing... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... An alluvial deposit is an accumulation of alluvium (sediment), sometimes containing valuable ore and gemstones, or simply consisting of gravel, sand, or clay, in the bed or former bed of a river. ... In geology, a placer deposit is a deposit of earth, sand, or gravel, containing valuable minerals in particles, especially by the side of a river, or in the bed of a mountain stream. ...

The primary source of gold is usually igneous rocks or surface concentrations. A deposit usually needs some form of secondary enrichment to form an economically viable ore deposit: either chemical or physical processes like erosion or solution or more generally metamorphism, which concentrates the gold in sulfide minerals or quartz. There are several primary deposit types, common ones are termed reef or vein. Primary deposits can be weathered and eroded, with most of the gold being transported into stream beds where it congregates with other heavy minerals to form placer deposits. In all these deposits the gold is in its native form. Another important ore type is in sedimentary black shale and limestone deposits containing finely disseminated gold and other platinum group metals. Look up Erosion in Wiktionary, the free dictionary Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case... Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Limey shale overlaid by limestone. ... General Name, Symbol, Number Platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10 , 6, d Density, Hardness 21450 kg/m³, 3. ...

Gold occurs in sea water at 0.1 to 2 mg/1000 kg (0.1 - 2 ppb) depending on sample location. The milligram (symbol mg) is an SI unit of mass. ... This page refers to concentration in the chemical sense. ...

As of 2001 it is estimated that there are 145,000 tonnes (approx 5 billion oz) of gold.

Production

The entrance to an underground gold mine in Victoria, Australia

Economic gold extraction can be achieved from ore grades as little as 0.5 g/1000 kg (0.5 ppm) on average in large easily mined deposits, typical ore grades in open-pit mines are 1 - 5 g/1000 kg (1-5 ppm), ore grades in underground or hard rock mines are usually at least 3 g/1000 kg (3 ppm) on average. Ore grades of 30 g/1000 kg (30 ppm) are usually needed before gold will be visible to the naked eye, therefore even in gold mines you will often not see any gold. Download high resolution version (1600x1067, 770 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1600x1067, 770 KB) Wikipedia does not have an article with this exact name. ... Gold extraction or recovery from its ores may require a combination of comminution, mineral processing, hydrometallurgical, and pyrometallurgical processes to be performed on the ore. ... The El Chino mine located near Silver City, New Mexico is an open-pit copper mine Open-pit mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow. ... Hard rock mining refers to various techniques used to mine ore bodies by creating underground rooms or stopes supported by surrounding pillars of standing rock. ...

Gold ore

Gold is extracted from alluvium ores by techniques of placer mining and from hard rock ores using extractive metallurgy. Refining of the metal is frequently accomplished by chlorination or electrolysis. Gold occurs in sea water at 0.1 to 2 mg/1000 kg (0.1 - 2 ppb) depending on sample location. However, as of 2004 there is no profitable method for recovering gold from sea water. Commons:Image:GoldOreUSGOV.jpg File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Commons:Image:GoldOreUSGOV.jpg File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Gold extraction or recovery from its ores may require a combination of comminution, mineral processing, hydrometallurgical, and pyrometallurgical processes to be performed on the ore. ... A sluice box used in placer mining Placer mining (pronounced plass-er) is a open-pit or open-cast form of mining by which certain valuable minerals are extracted from the earth without tunneling. ... Extractive metallurgy is the practice of extracting metal from ore, purifying it, and recycling it. ... Chlorination is the process of adding the element chlorine to water to make it fit for human consumption (potable) or to water intended for swimming or bathing in order to keep it from spreading disease. ... In chemistry and manufacturing, electrolysis is a method of separating bonded elements and compounds by passing an electric current through them. ... The milligram (symbol mg) is an SI unit of mass. ... This page refers to concentration in the chemical sense. ... 2004 is a leap year starting on Thursday of the Gregorian calendar. ...

Since the 1880s South Africa has been the source for about two-thirds of the world's gold supply. The city of Johannesburg was built atop the world's greatest gold finds. Gold fields in the Orange Free State and the Transvaal were deep and require the world's deepest mines. The Boer War of 1899–1901 between the British and the white Boers was at least partly over the rights of miners and possession of the gold wealth in South Africa. Other major producers are Canada, United States and Western Australia. Mines in South Dakota and Nevada supply two-thirds of gold used in the United States. City motto: Unity in Development Province Gauteng Mayor Amos Masondo Area  - % water 1,644 km² 0. ... Flag of the Orange Free State The Orange Free State (Afrikaans: Oranje Vrystaat) was the historical precursor to the present day Free State province of the Republic of South Africa. ... Flag of Transvaal The Transvaal was one of the provinces of South Africa from 1910 until 1994. ... Boer guerrillas during the Second Boer War There were two Boer wars, one from December 16, 1880-March 23, 1881 and the second from October 11, 1899-May 31, 1902 both between the British and the settlers of Dutch, French and German origin (called Boers, Afrikaners or Voortrekkers) in South... 1899 was a common year starting on Sunday (see link for calendar). ... 1901 was a common year starting on Tuesday (see link for calendar). ... Afrikaners are white South Africans of predominantly Calvinist Dutch, German, French Huguenot, Friesian and Walloon descent who speak Afrikaans. ... Motto: Cygnis Insignis (Distinguished by its swans) Nickname: Wildflower State Other Australian states and territories Capital Perth Government Governor Premier Const. ... State nickname: The Mount Rushmore State Other U.S. States Capital Pierre Largest city Sioux Falls Governor Mike Rounds (R) Official languages English Area 199,905 km² (17th)  - Land 196,735 km²  - Water 3,173 km² (1. ... State nickname: Silver State, Battle Born State (official) Other U.S. States Capital Carson City Largest city Las Vegas Governor Kenny Guinn (R) Official languages None Area 286,367 km² (7th)  - Land 284,396 km²  - Water 1,971 km² (0. ...

Compounds/isotopes

Auric chloride (AuCl₃) and chlorauric acid (HAuCl₄) are the most common compounds of gold. Gold compounds can be aurous (univalent, +1) or auric (trivalent, +3). Gold also can under extreme conditions form a +5 state with fluorine (gold pentafluoride, AuF₅), as well as (unusually for a metal), a -1 state. Such compounds containing the Au^- anion are called aurides and include caesium auride, CsAu, RbAu, and tetramethylammonium auride, (CH₃)₄N⁺ Au^-. General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Atomic mass 35. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... An anion is an ion with negative charge. ... General Name, Symbol, Number caesium, Cs, 55 Chemical series alkali metals Group, Period, Block 1, 6, s Appearance silvery gold Atomic mass 132. ... General Name, Symbol, Number rubidium, Rb, 37 Chemical series alkali metals Group, Period, Block 1, 5, s Appearance silvery white Atomic mass 85. ...

Although gold is a noble metal it can form many compounds (auric chloride and chloroauric acid are the most common). It also forms: Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. ... Gold(III) chloride, traditionally called auric chloride, is one of the most common compounds of gold. ...

• It dissolves in Aqua regia to form the AuCl₄^- ion
• Gold halides (F,Cl,Br,I)
• Gold chalcogenides (O, S, Se,Te)
• Gold cluster compounds
• Aurous hydrazide: an explosive olive-green powder, AuN₂H₄, known archaically as aurum fulminans

There is only one stable isotope of gold, and 18 radioisotopes with Au-195 being the most stable with a half-life of 186 days. Aqua regia (Latin for royal water) is a highly corrosive, fuming yellow liquid, formed by a fresh mixture of concentrated nitric acid (otherwise known as aqua fortis) and concentrated hydrochloric acid, usually in the ratio of one to three. ... Gold halides are compounds of gold with the halogens. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ... General Name, Symbol, Number chlorine, Cl, 17 Chemical series halogens Group, Period, Block 17, 3, p Appearance yellowish green Atomic mass 35. ... General Name, Symbol, Number bromine, Br, 35 Chemical series halogens Group, Period, Block 17, 4, p Appearance gas/liquid: red-brown solid: metallic luster Atomic mass 79. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... Gold chalcogenides are gold compounds with anions from periodic table group 16, known as the chalcogens. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ... General Name, Symbol, Number selenium, Se, 34 Chemical series nonmetals Group, Period, Block 16, 4, p Appearance gray, metallic luster Atomic mass 78. ... General Name, Symbol, Number tellurium, Te, 52 Series metalloids Group, Period, Block 16 (VIA), 5, p Density, Hardness 6240 kg/m3, 2. ... Hydrazine is a chemical compound with formula N2H4 used as a rocket fuel. ... Isotopes are forms of a chemical element whose nuclei have the same atomic number, Z, but different atomic masses, A. The word isotope, meaning at the same place, comes from the fact that all isotopes of an element are located at the same place on the periodic table. ... A radionuclide is an atom with an unstable nucleus. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ...

Precautions

The human body does not absorb gold very well, thus compounds of gold are not normally very toxic. Liver and kidney damage has, however, been reported for up to 50% of arthritis patients treated with gold-containing drugs. Gold used in dentistry is widely regarded as the safest form of restorative material, as well as the most successful. The liver is an organ in vertebrates, including humans. ... Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ...

References

• Los Alamos National Laboratory – Gold
• The Columbia Electronic Encyclopedia, 6th ed

External links

• WebElements.com – Gold (also used as a reference)
• EnvironmentalChemistry.com – Gold (also used as a reference)
• Mineral Galleries - Native Gold
• Gold prices and economy
• Facts, figures and arguments for gold bugs!
• Retail gold exchange
• Gold, Greed & Genocide
• Getting Gold 1898 book