Gold,Mercury

Gold is a chemical element with the symbol Au (from Latin: aurum "gold") and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Sony VAIO VGN-G21XP/B Battery

Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive solid chemical elements. The metal therefore occurs often in free elemental (native) form, as nuggets or grains in rocks, in veins and in alluvial deposits. Less commonly, it occurs in minerals as gold compounds, usually with tellurium. Sony VAIO VGN-G2AANS Battery

Gold resists attacks by individual acids, but it can be dissolved by the aqua regia (nitro-hydrochloric acid), so named because it dissolves gold. Gold also dissolves in alkaline solutions of cyanide, which have been used in mining. Gold dissolves in mercury, forming amalgam alloys. Sony VAIO VGN-G2AAPS Battery

Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to confirm the presence of gold in items, giving rise to the term the acid test.

Gold has been a valuable and highly sought-after precious metal for coinage, jewelry, and other arts since long before the beginning of recorded history. Sony VAIO VGN-G2AAPSA Battery

Gold standards have been the most common basis for monetary policies throughout human history, being widely supplanted by fiat currency only in the late 20th century. Gold has also been frequently linked to a wide variety of symbolisms and ideologies. A total of 165,000 tonnes of gold have been mined in human history, as of 2009. Sony VAIO VGN-G2AAPSB Battery

This is roughly equivalent to 5.3 billion troy ounces or, in terms of volume, about 8500 m³, or a cube 20.4 m on a side. The world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry.^[3] Sony VAIO VGN-G2AAPSC Battery

Besides its widespread monetary and symbolic functions, gold has many practical uses in dentistry, electronics, and other fields. Its high malleability, ductility, resistance to corrosion and most other chemical reactions, and conductivity of electricity led to many uses of gold, including electric wiring, colored-glass production and even gold leaf eating. Sony VAIO VGN-G2KAN Battery

Characteristics

Gold is the most malleable and ductile of all metals; a single gram can be beaten into a sheet of 1 square meter, or an ounceinto 300 square feet. Gold leaf can be beaten thin enough to become translucent. Sony VAIO VGN-G2KANA Battery

The transmitted light appears greenish blue, because gold strongly reflects yellow and red.^[4] Such semi-transparent sheets also strongly reflect infrared light, making them useful as infrared (radiant heat) shields in visors of heat-resistant suits, and in sun-visors for spacesuits.^[5] Sony VAIO VGN-G2KBNA Battery

Gold readily creates alloys with many other metals. These alloys can be produced to modify the hardness and other metallurgical properties, to control melting point or to create exotic colors (see below).^[6] Gold is a good conductor of heatand electricity and reflects infrared radiation strongly. Sony VAIO VGN-NR160E/S Battery

Chemically, it is unaffected by air, moisture and most corrosivereagents, and is therefore well suited for use in coins and jewelry and as a protective coating on other, more reactive, metals. However, it is not chemically inert.

Common oxidation states of gold include +1 (gold(I) or aurous compounds) and +3 (gold(III) or auric compounds). Sony VAIO VGN-NR160E/T Battery

Gold ions in solution are readily reduced and precipitated out as gold 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.

High quality pure metallic gold is tasteless and scentless, in keeping with its resistance to corrosion (it is metal ions which confer taste to metals).^[7] Sony VAIO VGN-NR160E/W Battery

In addition, gold is very dense, a cubic meter weighing 19,300 kg. By comparison, the density of lead is 11,340 kg/m³, and that of the densest element, osmium, is 22,610 kg/m³.

Color

Whereas most other pure metals are gray or silvery white, gold is yellow. Sony VAIO VGN-NR180E/S Battery

This color is determined by the density of loosely bound (valence) electrons; those electrons oscillate as a collective "plasma" medium described in terms of a quasiparticle called plasmon. The frequency of these oscillations lies in the ultraviolet range for most metals, but it falls into the visible range for gold due to subtle relativistic effects that affect theorbitals around gold atoms.^[8][9] Sony VAIO VGN-NR180E/T Battery

Similar effects impart a golden hue to metallic caesium(see relativistic quantum chemistry).

Common colored gold alloys such as rose gold can be created by the addition of various amounts of copper and silver, as indicated in the triangular diagram to the left. Alloys containing palladium or nickel are also important in commercial jewelry as these produce white gold alloys. Sony VAIO VGN-NR290E/S Battery

Less commonly, addition of manganese, aluminium, iron, indium and other elements can produce more unusual colors of gold for various applications.^[6]

Isotopes

Gold has only one stable isotope, ¹⁹⁷Au, which is also its only naturally occurring isotope. Thirty-six radioisotopes have been synthesized ranging in atomic mass from 169 to 205. Sony VAIO VGN-NR290E/T Battery

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, ? decay, and ?+ decay. The exceptions are ¹⁹⁵Au, which decays by electron capture, and ¹⁹⁶Au, which decays most often by electron capture (93%) with a minor ?- decay path (7%).^[10] Sony VAIO VGN-NR298E/S Battery

All of gold's radioisotopes with atomic masses above 197 decay by ?- decay.^[11]

At least 32 nuclear isomers have also been characterized, ranging in atomic mass from 170 to 200. Within that range, only¹⁷⁸Au, ¹⁸⁰Au, ¹⁸¹Au, ¹⁸²Au, and ¹⁸⁸Au do not have isomers. Gold's most stable isomer is ^198m2Au with a half-life of 2.27 days. Sony VAIO VGN-NR460E/L Battery

Gold's least stable isomer is ^{177 m2}Au with a half-life of only 7 ns. ^{184 m1}Au has three decay paths: ?+ decay, isomeric transition, and alpha decay. No other isomer or isotope of gold has three decay paths.^[11]

Monetary exchange

Gold has been widely used throughout the world as a vehicle for monetary exchange, Sony VAIO VGN-NR460E/P Battery

either by issuance and recognition of gold coins or other bare metal quantities, or through gold-convertible paper instruments by establishing gold standards in which the total value of issued money is represented in a store of gold reserves.

However, production has not grown in relation to the world's economies. Sony VAIO VGN-NR498E/L Battery

Today, gold mining output is declining.^[12] With the sharp growth of economies in the 20th century, and increasing foreign exchange, the world's gold reserves and their trading market have become a small fraction of all markets and fixed exchange rates of currencies to gold were no longer sustained. Sony VAIO VGN-NR498E/S Battery

At the beginning of World War I the warring nations moved to a fractional gold standard, inflating their currencies to finance the war effort. After World War IIgold was replaced by a system of convertible currency following the Bretton Woods system. Sony VAIO VGN-NR498E/T Battery

Gold standards and the direct convertibility of currencies to gold have been abandoned by world governments, being replaced by fiat currency in their stead. Switzerland was the last country to tie its currency to gold; it backed 40% of its value until the Swiss joined the International Monetary Fund in 1999.^[13] Sony VAIO VGN-NR498E/W Battery

Pure gold is too soft for day-to-day monetary use and is typically hardened by alloying with copper, silver or other base metals. The gold content of alloys is measured in carats (k). Pure gold is designated as 24k. English gold coins intended for circulation from 1526 into the 1930s were typically a standard 22k alloy called crown gold, Sony VAIO VGN-NR50 Battery

for hardness (American gold coins for circulation after 1837 contained the slightly lower amount of 0.900 fine gold, or 21.6 kt).

Investment

Many holders of gold store it in form of bullion coins or bars as a hedge against inflation or other economic disruptions. However, some economists do not believe gold serves as a hedge against inflation or currency depreciation.^[14] Sony VAIO VGN-NR50B Battery

The ISO 4217 currency code of gold is XAU.

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, the British gold sovereign, and the South African Krugerrand continue to be minted in 22k metal in historical tradition. Sony VAIO VGN-NR51 Battery

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 purity of 99.99%.

Several other 99.99% pure gold coins are available. Sony VAIO VGN-NR51B Battery

In 2006, the United States Mint began production of the American Buffalo gold 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 popular modern coins include the Austrian Vienna Philharmonic bullion coin and the Chinese Gold Panda. Sony VAIO VGN-NR52 Battery

Jewelry

Because of the softness of pure (24k) gold, it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Alloys with lower caratage, typically 22k, 18k, 14k or 10k, contain higher percentages of copper, or other base metals or silver or palladium in the alloy. Sony VAIO VGN-NR52B Battery

Copper is the most commonly used base metal, yielding a redder color.^[15]

Eighteen-carat gold containing 25% copper is found in antique and Russian jewelry and has a distinct, though not dominant, copper cast, creating rose gold. Fourteen-carat gold-copper alloy is nearly identical in color to certain bronze alloys, and both may be used to produce police and other badges. Sony VAIO VGN-NR71B Battery

Blue gold can be made by alloying with iron and purple gold can be made by alloying withaluminium, although rarely done except in specialized jewelry. Blue gold is more brittle and therefore more difficult to work with when making jewelry.^[15]

Fourteen and eighteen carat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Sony VAIO VGN-NR71B2 Battery

White gold alloys can be made with palladium or nickel. White 18-carat gold containing 17.3% nickel, 5.5% zinc and 2.2% copper is silvery in appearance. Nickel is toxic, however, and its release from nickel white gold is controlled by legislation in Europe.^[15]

Alternative white gold alloys are available based on palladium, silver and other white metals,^[15] but the palladium alloys are more expensive than those using nickel. Sony VAIO VGN-NR72B Battery

High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver. The Japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects. Sony VAIO VGN-NS10E/S Battery

Medicine

In medieval times, gold was often seen as beneficial for the health, in the belief that something so rare and beautiful could not be anything but healthy. Even some modern esotericists and forms of alternative medicine assign metallic gold a healing power.^[16] Sony VAIO VGN-NS10J/S Battery

Some gold salts do have anti-inflammatory properties and are used as pharmaceuticals in the treatment of arthritis and other similar conditions.^[17] However, only salts and radioisotopes of gold are of pharmacological value, as elemental (metallic) gold is inert to all chemicals it encounters inside the body. Sony VAIO VGN-NS10L/S Battery

In modern times, injectable gold has been proven to help to reduce the pain and swelling of rheumatoid arthritis and tuberculosis.^[17][18]

Gold alloys are used in restorative dentistry, especially in tooth restorations, such as crowns and permanent bridges. Sony VAIO VGN-NS110E/L Battery

The gold alloys' slight malleability facilitates the creation of a superior molar mating surface with other teeth and produces results that are generally more satisfactory than those produced by the creation of porcelain crowns. The use of gold crowns in more prominent teeth such as incisors is favored in some cultures and discouraged in others. Sony VAIO VGN-NS110E/S Battery

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 reduction of gold chloride with citrate or ascorbate ions. Colloidal gold is used in research applications in medicine, biology andmaterials science. Sony VAIO VGN-NS110E/W Battery

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 presence and position of antigens on the surfaces of cells.^[19] Sony VAIO VGN-NS115N/S Battery

In ultrathin sections of tissues viewed by electron microscopy, the immunogold labels appear as extremely dense round spots at the position of the antigen.^[20] Colloidal gold is also the form of gold used as gold paint on ceramics prior to firing. Sony VAIO VGN-NS11ER/S Battery

Gold, or alloys of gold and palladium, are applied as conductive coating to biological specimens and other non-conducting materials such as plastics and glass to be viewed in a scanning electron microscope. The coating, which is usually applied by sputtering with an argon plasma, has a triple role in this application. Sony VAIO VGN-NS11E/S Battery

Gold's very high electrical conductivity drains electrical charge to earth, and its very high density provides stopping power for electrons in the electron beam, helping to limit the depth to which the electron beam penetrates the specimen. This improves definition of the position and topography of the specimen surface and increases thespatial resolution of the image. Sony VAIO VGN-NS11J/S Battery

Gold also produces a high output of secondary electrons when irradiated by an electron beam, and these low-energy electrons are the most commonly used signal source used in the scanning electron microscope.^[21]

The isotope gold-198, (half-life 2.7 days) is used in some cancer treatments and for treating other diseases.^[22] Sony VAIO VGN-NS11L/S Battery

Food and drink

• Gold can be used in food and has the E number 175.^[23]

Gold leaf, flake or dust is used on and in some gourmet foods, notably sweets and drinks as decorative ingredient.^[24] Sony VAIO VGN-NS11MR/S Battery

Gold flake was used by the nobility inMedieval Europe as a decoration in food and drinks, in the form of leaf, flakes or dust, either to demonstrate the host's wealth or in the belief that something that valuable and rare must be beneficial for one's health. Sony VAIO VGN-NS11M/S Battery

Danziger Goldwasser (German: Gold water of Danzig) or Goldwasser (English: Goldwater) is a traditional German herbal liqueur^[25] produced in what is today Gda?sk,Poland, and Schwabach, Germany, and contains flakes of gold leaf. Sony VAIO VGN-NS11SR/S Battery

• There are also some expensive (~$1000) cocktails which contain flakes of gold leaf.^[26] However, since metallic gold is inert to all body chemistry, it has no taste, it provides no nutrition, and it leaves the body unaltered.^[27]

Gold solder is used for joining the components of gold jewelry by high-temperature hard soldering or brazing. Sony VAIO VGN-NS11S/S Battery

If the work is to be of hallmarking quality, gold solder must match the carat weight of the work, and alloy formulas are manufactured in most industry-standard carat weights to color match yellow and white gold. Gold solder is usually made in at least three melting-point ranges referred to as Easy, Medium and Hard. Sony VAIO VGN-NS11ZR/S Battery

• By using the hard, high-melting point solder first, followed by solders with progressively lower melting points, goldsmiths can assemble complex items with several separate soldered joints.


• Gold can be made into thread and used in embroidery.

Gold produces a deep, intense red color when used as a coloring agent in cranberry glass. Sony VAIO VGN-NS11Z/S Battery

In photography, gold toners are used to shift the color of silver bromide black-and-white prints towards brown or blue tones, or to increase their stability. Used on sepia-toned prints, gold toners produce red tones. Kodak published formulas for several types of gold toners, which use gold as the chloride.^[28] Sony VAIO VGN-NS12M/S Battery

As gold is a good reflector of electromagnetic radiation such as infrared and visible light as well as radio waves, it is used for the protective coatings on many artificial satellites, in infrared protective faceplates in thermal protection suits and astronauts' helmets and in electronic warfare planes like the EA-6B Prowler. Sony VAIO VGN-NS12M/W Battery

• Gold is used as the reflective layer on some high-end CDs.


• Automobiles may use gold for heat dissipation. McLaren uses gold foil in the engine compartment of its F1 model.^[29]

Gold can be manufactured so thin that it appears transparent. It is used in some aircraft cockpit windows for de-icing or anti-icing by passing electricity through it. Sony VAIO VGN-NS12S/S Battery

• The heat produced by the resistance of the gold is enough to deter ice from forming.^[30]

Electronics

The concentration of free electrons in gold metal is 5.90×10²² cm^?3. Gold is highly conductive to electricity, Sony VAIO VGN-NS21M/P Battery

and has been used forelectrical wiring in some high-energy applications (only silver and copper are more conductive per volume, but gold has the advantage of corrosion resistance). For example, gold electrical wires were used during some of the Manhattan Project's atomic experiments, but large high current silver wires were used in the calutron isotope separator magnets in the project. Sony VAIO VGN-NS21M/W Battery

Though gold is attacked by free chlorine, its good conductivity and general resistance to oxidation and corrosion in other environments (including resistance to non-chlorinated acids) has led to its widespread industrial use in the electronic era as a thin layer coatingelectrical connectors of all kinds, thereby ensuring good connection. Sony VAIO VGN-NS21S/S Battery

For example, gold is used in the connectors of the more expensive electronics cables, such as audio, video and USB cables. The benefit of using gold over other connector metals such as tin in these applications is highly debated. Gold connectors are often criticized by audio-visual experts as unnecessary for most consumers and seen as simply a marketing ploy. Sony VAIO VGN-NS21S/W Battery

However, the use of gold in other applications in electronic sliding contacts in highly humid or corrosive atmospheres, and in use for contacts with a very high failure cost (certain computers, communications equipment, spacecraft, jet aircraft engines) remains very common.^[31] Sony VAIO VGN-NS21Z/S Battery

Besides sliding electrical contacts, gold is also used in electrical contacts because of its resistance to corrosion, electrical conductivity, ductility and lack of toxicity.^[32] Switch contacts are generally subjected to more intense corrosion stress than are sliding contacts. Fine gold wires are used to connect semiconductor devices to their packages through a process known as wire bonding. Sony VAIO VGN-NS31M/P Battery

Commercial chemistry

Gold is attacked by and dissolves in alkaline solutions of potassium or sodium cyanide, to form the salt gold cyanide—a technique that has been used in extracting metallic gold from ores in the cyanide process. Sony VAIO VGN-NS31M/W Battery

Gold cyanide is the electrolyte used in commercialelectroplating of gold onto base metals and electroforming.

Gold chloride (chloroauric acid) solutions are used to make colloidal gold by reduction with citrate or ascorbate ions. Sony VAIO VGN-NS31S/S Battery

Gold chloride and gold oxide are used to make highly valued cranberry or red-colored glass, which, like colloidal gold suspensions, contains evenly sized spherical gold nanoparticles.^[33]

Gold has been known and used by artisans since the Chalcolithic. Gold artifacts in the Balkans appear from the 4th millennium BC, such as those found in the Varna Necropolis, Bulgaria. Sony VAIO VGN-NS31Z/P Battery

Gold artifacts such as the golden hats and the Nebra disk appeared in Central Europe from the 2nd millennium BC Bronze Age.

Egyptian hieroglyphs from as early as 2600 BC describe gold, which king Tushratta of the Mitanni claimed was "more plentiful than dirt" in Egypt.^[34] Sony VAIO VGN-NS31Z/S Battery

Egypt and especially Nubia had the resources to make them major gold-producing areas for much of history. The earliest known map is known as the Turin Papyrus Map and shows the plan of a gold 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. Sony VAIO VGN-NS31Z/W Battery

Large mines were also present across the Red Sea in what is now Saudi Arabia.

The legend of the golden fleece may refer to the use of fleeces to trap gold dust from placer deposits in the ancient world. Gold is mentioned frequently in the Old Testament, starting with Genesis 2:11 (at Havilah) and is included with the gifts of the magi in the first chapters of Matthew New Testament. Sony VAIO VGN-NS38M/P Battery

The Book of Revelation 21:21 describes the city of New Jerusalem as having streets "made of pure gold, clear as crystal". 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 around 610 BC.^[35] Sony VAIO VGN-NS38M/W Battery

From the 6th or 5th century BC, the Chu (state) circulated the Ying Yuan, one kind of square gold coin.

In Roman metallurgy, new methods for extracting gold on a large scale were developed by introducing hydraulic mining methods, especially in Hispania from 25 BC onwards and in Dacia from 106 AD onwards. Sony VAIO VGN-NS130E/L Battery

One of their largest mines was at Las Medulas in León (Spain), where seven long aqueducts enabled them to sluice most of a large alluvial deposit. The mines at Ro?ia Montan?in Transylvania were also very large, and until very recently, still mined by opencast methods. Sony VAIO VGN-NS130E/S Battery

They also exploited smaller deposits in Britain, such as placer and hard-rock deposits at Dolaucothi. The various methods they used are well described by Pliny the Elderin his encyclopedia Naturalis Historia written towards the end of the first century AD. Sony VAIO VGN-NS130E/W Battery

The Mali Empire in Africa was famed throughout the old world for its large amounts of gold. Mansa Musa, ruler of the empire (1312–1337) became famous throughout the old world for his great hajj to Mecca in 1324. Sony VAIO VGN-NS140E/L Battery

When he passed through Cairo in July 1324, he was reportedly accompanied by a camel train that included thousands of people and nearly a hundred camels. He gave away so much gold that it depressed the price in Egypt for over a decade.^[36] A contemporary Arab historian remarked: Sony VAIO VGN-NS140E/S Battery

Gold 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 value fell and it cheapened in price and has remained cheap till now. 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 amount of gold which they brought into Egypt and spent there Sony VAIO VGN-NS140E/W Battery

—Chihab Al-Umari^[37]

The European exploration of the Americas was fueled in no small part by reports of the gold ornaments displayed in great profusion byNative American peoples, especially in Central America, Peru, Ecuador and Colombia. Sony VAIO VGN-NS190J/L Battery

The Aztecs regarded gold as literally the product of the gods, calling it "god excrement" (teocuitlatl in Nahuatl).^[38] However, for the indigenous peoples of North America, gold was considered useless, and they saw much greater value in other minerals, which were directly related to their utility, such as obsidian,flint, and slate.^[39] Sony VAIO VGN-NS190J/S Battery

Although the price of some platinum group metals can be much higher, gold has long been considered the most desirable of 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. Sony VAIO VGN-NS190J/W Battery

Gold as a sign of wealth and prestige was ridiculed by Thomas More in his treatise Utopia. On that imaginary island, gold is so abundant that it is used to make chains for slaves, tableware and lavatory-seats. When ambassadors from other countries arrive, dressed in ostentatious gold jewels and badges, the Utopians mistake them for menial servants, paying homage instead to the most modestly dressed of their party. Sony VAIO VGN-NS235J/L Battery

There is an age-old tradition of biting gold to test its authenticity. Although this is certainly not a professional way of examining gold, the bite test should score the gold because gold is a soft metal, as indicated by its score on the Mohs' scale of mineral hardness. The purer the gold the easier it should be to mark it. Sony VAIO VGN-NS235J/P Battery

Painted lead can cheat this test because lead is softer than gold (and may invite a small risk oflead poisoning if sufficient lead is absorbed by the biting).

Gold in antiquity was relatively easy to obtain geologically; however, 75% of all gold ever produced has been extracted since 1910.^[40] Sony VAIO VGN-NS235J/S Battery

Sony VAIO VGN-NS235J/W Battery

It has been estimated that all gold ever refined would form a single cube 20 m (66 ft) on a side (equivalent to 8,000 m³).^[40]

One main goal of the alchemists was to produce gold from other substances, such as lead — presumably by the interaction with a mythical substance called thephilosopher's stone. Sony VAIO VGN-NS240E/L Battery

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 and the ancientChinese character for the Sun. Sony VAIO VGN-NS290J/L Battery

For modern creation of artificial gold by neutron capture, see gold synthesis.

During the 19th century, gold rushes occurred whenever large gold deposits were discovered. The first documented discovery of gold in the United States was at theReed Gold Mine near Georgeville, North Carolina in 1803.^[41] Sony VAIO VGN-NS290J/S Battery

The first major gold strike in the United States occurred in a small north Georgia town calledDahlonega.^[42] Further gold rushes occurred in California, Colorado, the Black Hills, Otago in New Zealand, Australia, Witwatersrand in South Africa, and theKlondike in Canada. Sony VAIO VGN-NS50B/L Battery

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

Occurrence

Gold's atomic number of 79 makes it one of the higher atomic number elements which occur naturally. Sony VAIO VGN-NS50B/W Battery

Like all elements with atomic numbers larger than iron, gold is thought to have been formed from a supernova nucleosynthesis process. Their explosions scattered metal-containing dusts (including heavy elements like gold) into the region of space in which they later condensed into our solar system and the Earth.^[43] Sony VAIO VGN-NS51B/L Battery

Because the Earth was molten when it was just formed, almost all of the gold present on Earth sank into the core. Most of the gold that is present today in the Earth's crust and mantle was delivered to Earth by asteroid impacts during the late heavy bombardment.^[44] Sony VAIO VGN-NS51B/P Battery

On Earth, whenever elemental gold occurs, it appears most often as a metal solid solution of gold with silver, i.e. a gold silver alloy. Such alloys usually have a silver content of 8–10%. Electrum is elemental gold with more than 20% silver. Electrum's color runs from golden-silvery to silvery, dependent upon the silver content. Sony VAIO VGN-NS51B/W Battery

The more silver, the lower the specific gravity.

Gold is found in ores made up of rock with very small or microscopic particles of gold. This gold ore is often found together with quartz or sulfide minerals such as Fool's Gold, which is a pyrite.^[45] These are called lode deposits. Sony VAIO VGN-NS52JB/L Battery

Native gold 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 surface of gold-bearing veins owing to the oxidation of accompanying minerals followed by weathering, Sony VAIO VGN-NS52JB/P Battery

and 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, and as the rare bismuthide maldonite (Au₂Bi) and antimonide aurostibite (AuSb₂). Sony VAIO VGN-NS52JB/W Battery

Gold also occurs in rare alloys with copper, lead, andmercury: the minerals auricupride (Cu₃Au), novodneprite (AuPb₃) and weishanite ((Au, Ag)₃Hg₂).

Recent research 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.^[46] Sony VAIO VGN-NS70B/W Battery

The world's oceans contain gold. Measured concentrations of gold in the Atlantic and Northeast Pacific are 50–150 fmol/L or 10–30 parts per quadrillion (about 10–30 g/km³). In general, Au concentrations for Atlantic and Pacific samples are the same (~50 fmol/L) but less certain. Sony VAIO VGN-NS71B/W Battery

Mediterranean deep waters contain higher concentrations of Au (100–150 fmol/L) attributed to wind-blown dust and/or rivers. At 10 parts per quadrillion the Earth's oceans would hold 15,000 tons of gold.^[47] These figures are three orders of magnitude less than reported in the literature prior to 1988, indicating contamination problems with the earlier data. Sony VAIO VGN-NS72JB/W Battery

A number of people have claimed to be able to economically recover gold from sea water, but so far they have all been either mistaken or acted in an intentional deception. A so-called reverend, Prescott Jernegan ran a gold-from-seawater swindle in theUnited States in the 1890s. A British fraudster ran the same scam in England in the early 1900s.^[48] Sony VAIO VGN-NS90HS Battery

Fritz Haber (the German inventor of the Haber process) did research on the extraction of gold from sea water in an effort to help pay Germany's reparations following World War I.^[49] Based on the published values of 2 to 64 ppb of gold in seawater a commercially successful extraction seemed possible. Sony VAIO VGN-NS92JS Battery

After analysis of 4,000 water samples yielding an average of 0.004 ppb it became clear that the extraction would not be possible and he stopped the project.^[50] No commercially viable mechanism for performing gold extraction from sea water has yet been identified. Gold synthesis is not economically viable and is unlikely to become so in the foreseeable future. Sony VAIO VGN-NS92XS Battery

Production

Gold extraction is most economical in large, easily mined deposits. Ore grades as little as 0.5 mg/kg (0.5 parts per million, ppm) can be economical. Typical ore grades in open-pit mines are 1–5 mg/kg (1–5 ppm); ore grades in underground or hard rock mines are usually at least 3 mg/kg (3 ppm). Sony VAIO VGN-NW11S/S Battery

Because ore grades of 30 mg/kg (30 ppm) are usually needed before gold is visible to the naked eye, in most gold mines the gold is invisible.

Since the 1880s, South Africa has been the source for a large proportion of the world's gold supply, with about 50% of all gold ever produced having come from South Africa. Sony VAIO VGN-NW11S/T Battery

Production in 1970 accounted for 79% of the world supply, producing about 1,480 tonnes. 2008 production was 2,260 tonnes. In 2007 China (with 276 tonnes) overtook South Africa as the world's largest gold producer, the first time since 1905 that South Africa has not been the largest.^[51] Sony VAIO VGN-NW11Z/S Battery

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 gold deposits the world has ever seen. Sony VAIO VGN-NW11Z/T Battery

Gold fields located within the basin in the Free Stateand Gauteng provinces are extensive in strike and dip requiring some of the world's deepest mines, with the Savuka and TauTonamines being currently the world's deepest gold mine at 3,777 m. The Second Boer War of 1899–1901 between the British Empire and the Afrikaner Boers was at least partly over the rights of miners and possession of the gold wealth in South Africa. Sony VAIO VGN-NW21EF/S Battery

Other major producers are the United States, Australia, Russia and Peru. Mines in South Dakota and Nevada supply two-thirds of gold used in the United States. In South America, the controversial project Pascua Lama aims at exploitation of rich fields in the high mountains of Atacama Desert, at the border between Chile and Argentina. Sony VAIO VGN-NW21JF Battery

Today about one-quarter of the world gold output is estimated to originate from artisanal or small scale mining.^[52]

After initial production, gold is often subsequently refined industrially by the Wohlwill process which is based onelectrolysis or by the Miller process, that is chlorination in the melt. Sony VAIO VGN-NW21MF Battery

The Wohlwill process results in higher purity, but is more complex and is only applied in small-scale installations.^[53][54] Other methods of assaying and purifying smaller amounts of gold include parting and inquartation as well as cupellation, or refining methods based on the dissolution of gold in aqua regia.^[55] Sony VAIO VGN-NW21MF/W Battery

At the end of 2009, it was estimated that all the gold ever mined totaled 165,000 tonnes.^[2] This can be represented by a cube with an edge length of about 20.28 meters. At $1,600 per ounce, 165,000 tons of gold would have a value of $8.8 trillion. Sony VAIO VGN-NW21ZF Battery

The average gold mining and extraction costs were about US$317/oz in 2007, but these can vary widely depending on mining type and ore quality; global mine production amounted to 2,471.1 tonnes.^[56]

Most of the gold used in manufactured goods, jewelry, and works of art is eventually recovered and recycled. Sony VAIO VGN-NW31EF/W Battery

Some gold used in spacecraft and electronic equipment cannot be profitably recovered, but it is generally used in these applications in the form of extremely thin layers or extremely fine wires so that the total quantity used (and lost) is small compared to the total amount of gold produced and stockpiled. Sony VAIO VGN-NW31JF Battery

Thus there is little true consumption of new gold in the economic sense; the stock of gold remains essentially constant (at least in the modern world) while ownership shifts from one party to another.^[57] One estimate is that 85% of all the gold ever mined is still available in the world's easily recoverable stocks, with 15% having been lost, or used in non-recyclable industrial uses.^[58] Sony VAIO VGN-NW320F/B Battery

Consumption

The consumption of gold produced in the world is about 50% in jewelry, 40% in investments, and 10% in industry.

India is the world's largest single consumer of gold, as Indians buy about 25% of the world's gold,^[59] purchasing approximately 800 tonnes of gold every year, mostly for jewelry. Sony VAIO VGN-NW320F/TC Battery

India is also the largest importer of gold; in 2008, India imported around 400 tonnes of gold.^[60] Indian households hold 18,000 tonnes of gold which represents 11 per cent of the global stock and worth more than $950 billion.^[61]

Chemistry

Although gold is a noble metal, it forms many and diverse compounds. Sony VAIO VGN-NW35E Battery

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 tertiary phosphines. Au(I) compounds are typically linear. Sony VAIO VGN-NW380F/S Battery

A good example isAu(CN)₂^?, which is the soluble form of gold encountered in mining. Curiously, aurous complexes of water are rare. 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.^[63] Sony VAIO VGN-NW380F/T Battery

Au(III) (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.

Aqua regia, a 1:3 mixture of nitric acid and hydrochloric acid, dissolves gold. Sony VAIO VGN-NW50JB Battery

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. Sony VAIO VGN-NW51FB/N Battery

Some free halogens react with gold.^[64] Gold also reacts in alkaline solutions of potassium cyanide. With mercury, it forms anamalgam.

Less common oxidation states

Less common oxidation states of gold include ?1, +2, and +5. Sony VAIO VGN-NW51FB/W Battery

The ?1 oxidation state occurs in compounds containing the Au^? anion, called aurides. Caesium auride (CsAu), for example, crystallizes in the caesium chloridemotif.^[65] Other aurides include those of Rb⁺, K⁺, and tetramethylammonium (CH₃)₄N⁺.^[66]Gold has the highest Pauling electronegativity of any metal, with a value of 2.54, making the auride anion relatively stable. Sony VAIO VGN-NW70JB Battery

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 Au4+
2 cations.^[67][68] Sony VAIO VGN-NW71FB/N Battery

A noteworthy, legitimate gold(II) complex is the tetraxenonogold(II) cation, which contains xenon as a ligand, found in [AuXe₄](Sb₂F₁₁)₂.^[69]

Gold pentafluoride and its derivative anion, AuF?
6, is the sole example of gold(V), the highest verified oxidation state.^[70] Sony VAIO VGN-NW71FB/W Battery

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 that van der Waals bonding. The interaction is estimated to be comparable in strength to that of a hydrogen bond. Sony VAIO VGN-NW91FS Battery

Mixed valence compounds

Well-defined cluster compounds are numerous.^[66] In such cases, gold has a fractional oxidation state. A representative example is the octahedral species {Au(P(C₆H₅)₃)}₆²⁺. Gold chalcogenides, such as gold sulfide, feature equal amounts of Au(I) and Au(III). Sony VAIO VGN-NW91GS Battery

Toxicity

Pure metallic (elemental) gold is non-toxic and non-irritating when ingested^[71] and is sometimes used as a food decoration in the form of gold leaf. Metallic gold is also a component of the alcoholic drinks Goldschläger, Gold Strike, and Goldwasser. Sony VAIO VGN-NW91VS Battery

Metallic gold is approved as a food additive in the EU (E175 in the Codex Alimentarius). Although gold ion is toxic, the acceptance of metallic gold as a food additive is due to its relative chemical inertness, and resistance to being corroded or transformed into soluble salts (gold compounds) by any known chemical process which would be encountered in the human body. Sony VAIO VGN-SR11M Battery

Soluble compounds (gold salts) such as gold chloride are toxic to the liver and kidneys. Common cyanide salts of gold such as potassium gold cyanide, used in gold electroplating, are toxic by virtue of both their cyanide and gold content. There are rare cases of lethal gold poisoning from potassium gold cyanide.^[72][73] Sony VAIO VGN-SR11MR Battery

Gold toxicity 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 mostly women.^[74] Despite this, gold is a relatively non-potent contact allergen, in comparison with metals like nickel.^[75] Sony VAIO VGN-SR140D Battery

Price

Like other precious metals, gold is measured by troy weight and by grams. When it is alloyed with other metals the term carator karat is used to indicate the purity of gold present, with 24 carats being pure gold and lower ratings proportionally less. Sony VAIO VGN-SR140D/B Battery

The purity of a gold bar or coin can also be expressed as a decimal figure ranging from 0 to 1, known as the millesimal fineness, such as 0.995 being very pure.

The price of gold is determined through trading in the gold and derivatives markets, but a procedure known as the Gold Fixingin London, originating in September 1919, Sony VAIO VGN-SR140D/P Battery

provides a daily benchmark price to the industry. The afternoon fixing was introduced in 1968 to provide a price when US markets are open.

Historically gold coinage was widely used as currency; when paper money was introduced, it typically was a receiptredeemable for gold coin or bullion. Sony VAIO VGN-SR140D/S Battery

In a monetary system known as the gold standard, a certain weight of gold was given the name of a unit of currency. For a long period, the United States government set the value of the US dollar so that one troy ounce was equal to $20.67 ($664.56/kg), but in 1934 the dollar was devalued to $35.00 per troy ounce ($1125.27/kg). Sony VAIO VGN-SR140E Battery

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 further currency devaluationagainst increased gold demand.

On March 17, 1968, economic circumstances caused the collapse of the gold pool, Sony VAIO VGN-SR140E/B Battery

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. Sony VAIO VGN-SR140E/P Battery

Central banks still hold historical gold reserves as a store of value although the level has generally been declining. The largest gold depository in the world is that of the U.S. Federal Reserve Bank in New York, which holds about 3%^[76] of the gold ever mined, as does the similarly laden U.S. Bullion Depository at Fort Knox. Sony VAIO VGN-SR140E/S Battery

In 2005 the World Gold Council estimated total global gold supply to be 3,859 tonnes and demand to be 3,754 tonnes, giving a surplus of 105 tonnes.^[77]

Since 1968 the price of gold has ranged widely, from a high of $850/oz ($27,300/kg) on January 21, 1980, to a low of $252.90/oz ($8,131/kg) on June 21, 1999 (London Gold Fixing).^[78] Sony VAIO VGN-SR140N/S Battery

The period from 1999 to 2001 marked the "Brown Bottom" after a 20-year bear market.^[79] Prices increased rapidly from 1991, but the 1980 high was not exceeded until January 3, 2008 when a new maximum of $865.35 per troy ounce was set.^[80] Another record price was set on March 17, 2008 at $1023.50/oz ($32,900/kg).^[80] Sony VAIO VGN-SR165E/B Battery

In late 2009, gold markets experienced renewed momentum upwards due to increased demand and a weakening US dollar. On December 2, 2009, Gold passed the important barrier of US$1200 per ounce to close at $1215.^[81] Gold further rallied hitting new highs in May 2010 after the European Union debt crisis prompted further purchase of gold as a safe asset.^[82][83] Sony VAIO VGN-SR165E/P Battery

On March 1, 2011, gold hit a new all-time high of $1432.57, based on investor concerns regarding ongoing unrest in North Africa as well as in the Middle East.^[84]

Since April 2001 the gold price has more than quintupled in value against the US dollar, hitting a new all-time high of $1,913.50 on August 23, 2011,^[85] Sony VAIO VGN-SR165E/S Battery

prompting speculation that this long secular bear market has ended and a bull market has returned.^[86]

Symbolism

Gold has been highly valued in many societies throughout the ages. In keeping with this it has often had a strongly positive symbolic meaning closely connected to the values held in the highest esteem in the society in question. Sony VAIO VGN-SR190EBJ Battery

Gold may symbolize power, strength, wealth, warmth, happiness, love, hope, optimism, intelligence, justice, balance, perfection, summer, harvest and the sun.

Great human achievements are frequently rewarded with gold, in the form of gold medals, golden trophies and other decorations. Sony VAIO VGN-SR190EBQ Battery

Winners of athletic events and other graded competitions are usually awarded a gold medal (e.g., the Olympic Games). Many awards such as the Nobel Prize are made from gold as well. Other award statues and prizes are depicted in gold or are gold plated (such as the Academy Awards, the Golden Globe Awards, the Emmy Awards, the Palme d'Or, and the British Academy Film Awards). Sony VAIO VGN-SR190EEJ/C Battery

Aristotle in his ethics used gold symbolism when referring to what is now commonly known as the "golden mean". Similarly, gold is associated with perfect or divine principles, such as in the case of the "golden ratio".

Gold represents great value. Respected people are treated with the most valued rule, the "golden rule". Sony VAIO VGN-SR190NAB Battery

A company may give its most valued customers "gold cards" or make them "gold members". We value moments of peace and therefore we say: "silence is golden". In Greek mythology there was the "golden fleece".

Gold is further associated with the wisdom of aging and fruition. Sony VAIO VGN-SR190NBB Battery

The fiftieth wedding anniversary is golden. Our precious latter years are sometimes considered "golden years". The height of a civilization is referred to as a "golden age".

In Christianity gold has sometimes been associated with the extremities of utmost evil and the greatest sanctity. Sony VAIO VGN-SR190NDB Battery

In the Book of Exodus, the Golden Calf is a symbol of idolatry. In the Book of Genesis, Abraham was said to be rich in gold and silver, and Moses was instructed to cover the Mercy Seat of the Ark of the Covenant with pure gold. In Christian art the halos of Christ, Mary and the Christian saints are golden. Sony VAIO VGN-SR190NEB Battery

Medieval kings were inaugurated under the signs of sacred oil and a golden crown, the latter symbolizing the eternal shining light of heaven and thus a Christian king's divinely inspired authority. Wedding rings have long been made of gold. It is long lasting and unaffected by the passage of time and may aid in the ring symbolism of eternal vows before God and/or the sun and moon and the perfection the marriage signifies. Sony VAIO VGN-SR190NGB Battery

In Orthodox Christianity, the wedded couple is adorned with a golden crown during the ceremony, an amalgamation of symbolic rites.

In popular culture gold holds many connotations but is most generally connected to terms such as good or great, such as in the phrases: "has a heart of gold", "that's golden!", "golden moment", "then you're golden!" and "golden boy". Sony VAIO VGN-SR190PAB Battery

Gold also still holds its place as a symbol of wealth and through that, in many societies, success.

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver orhydrargyrum(from "hydr-" water and "argyros" silver). Sony VAIO VGN-SR190PCB Battery

A heavy, silvery d-block element, mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, and metals such as caesium, francium, gallium, and rubidium melt just above room temperature. Sony VAIO VGN-SR190PFB Battery

With a freezing point of ?38.83 °C and boiling pointof 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.^[1][2][3]

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Sony VAIO VGN-SR19VN Battery

Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water-soluble forms of mercury (such as mercuric chloride ormethylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury. Sony VAIO VGN-SR19VN Battery

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, some electrical switches, and other scientific apparatus, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. Sony VAIO VGN-SR19VRN Battery

It remains in use in scientific research applications and in amalgammaterial for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light. Sony VAIO VGN-SR19XN Battery

Physical properties

Mercury is a heavy, silvery-white metal. As compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity.^[4] Mercury has an exceptionally low melting temperature for a d-block metal. Sony VAIO VGN-SR19XN Battery

A complete explanation of this fact requires a deep excursion into quantum physics, but it can be summarized as follows: mercury has a unique electronic configuration where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d and 6s subshells. Sony VAIO VGN-SR210J/S Battery

As such configuration strongly resists removal of an electron, mercury behaves similarly to noble gas elements, which form weak bonds and thus easily melting solids. The stability of the 6s shell is due to the presence of a filled 4f shell. An f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus (seelanthanide contraction). Sony VAIO VGN-SR21M/S Battery

The absence of a filled inner f shell is the reason for the somewhat higher melting temperature of cadmium and zinc, although both these metals still melt easily and, in addition, have unusually low boiling points. Metals such as gold have atoms with one less 6s electron than mercury. Sony VAIO VGN-SR21RM/H Battery

Those electrons are more easily removed and are shared between the gold atoms forming relatively strong metallic bonds.^[2][5] At its freezing point (?38.86 °C), the density of mercury is^[6] 13.534 g/cm³. Sony VAIO VGN-SR21RM/S Battery

Chemical properties

Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentratedsulfuric acidand nitric acid or aqua regia dissolve it to give sulfate,nitrate , and chloride salts. Sony VAIO VGN-SR220J/B Battery

Like silver, mercury reacts with atmospherichydrogen sulfide. Mercury even reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury vapors (spill kits also use activated carbon and powdered zinc).^[7]

Amalgams

Mercury dissolves to form amalgams with gold, zinc and many other metals. Sony VAIO VGN-SR220J/H Battery

Because iron is an exception, iron flasks have been traditionally used to trade mercury. Other metals that do not form amalgams with mercury include tantalum, tungsten and platinum. Sodium amalgam is a common reducing agent in organic synthesis.

Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Sony VAIO VGN-SR240J/B Battery

Since the amalgam reacts with air to give aluminium oxide, small amounts of mercury corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.^[8] Sony VAIO VGN-SR240N/B Battery

Isotopes

There are seven stable isotopes of mercury with ²⁰²Hg being the most abundant (29.86%). The longest-livedradioisotopesare ¹⁹⁴Hg with a half-life of 444 years, and ²⁰³Hg with a half-life of 46.612 days. Sony VAIO VGN-SR290JTH Battery

Most of the remaining radioisotopes have half-lives that are less than a day. ¹⁹⁹Hg and ²⁰¹Hg are the most often studied NMR-active nuclei, having spins of ¹?₂ and ³?₂ respectively.^[4]

In China and Tibet, mercury use was thought to prolong life, heal fractures, and maintain generally good health, Sony VAIO VGN-SR290JTJ Battery

although it is now known that exposure to mercury leads to serious adverse health effects.^[10] One of China's emperors, Qín Sh? Huáng Dì — allegedly buried in a tomb that contained rivers of flowing mercury on a model of the land he ruled, representative of the rivers of China —Sony VAIO VGN-SR290JTQ Battery

was killed by drinking a mercury and powdered jade mixture formulated byQin alchemists (causing liver failure, mercury poisoning, and brain death) who intended to give him eternal life.^[11][12]

The ancient Greeks used mercury in ointments; the ancient Egyptians and the Romans used it incosmetics which sometimes deformed the face. Sony VAIO VGN-SR290JVB/C Battery

In Lamanai, once a major city of the Maya civilization, a pool of mercury was found under a marker in a Mesoamerican ballcourt.^[13][14] By 500 BC mercury was used to make amalgams (Medieval Latin amalgama, "alloy of mercury") with other metals.^[15]

Alchemists thought of mercury as the First Matter from which all metals were formed. Sony VAIO VGN-SR290JVH/C Battery

They believed that different metals could be produced by varying the quality and quantity of sulfur contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists.^[16] Sony VAIO VGN-SR290NTB Battery

Hg is the modern chemical symbol for mercury. It comes from hydrargyrum, a Latinized form of the Greek word ?????????? (hydrargyros), which is a compound word meaning "water-silver" (hydr- = water, argyros = silver) — since it is liquid like water and shiny like silver. Sony VAIO VGN-SR29VN/S Battery

The element was named after the Roman godMercury, known for speed and mobility. It is associated with the planet Mercury; the astrological symbol for the planet is also one of the alchemical symbols for the metal; the Indian word for alchemy is Rasav?tam which means "the way of mercury".^[17] Sony VAIO VGN-SR29XN/S Battery

Mercury is the only metal for which the alchemical planetary name became the common name.^[16]

The mines in Almadén (Spain), Monte Amiata (Italy), and Idrija (now Slovenia) dominated the mercury production from the opening of the mine in Almadén 2500 years ago until new deposits were found at the end of the 19th century.^[18] Sony VAIO VGN-SR2RVN/S Battery

Occurrence

Mercury is an extremely rare element in the Earth's crust, having an average crustal abundance by mass of only 0.08 parts per million (ppm).^[19] However, because it does not blend geochemically with those elements that constitute the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element's abundance in ordinary rock. Sony VAIO VGN-SR390NAB Battery

The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a native metal (rare) or incinnabar, corderoite, livingstonite and other minerals, with cinnabar (HgS) being the most common ore.^[20] Sony VAIO VGN-SR390NAH Battery

Mercury ores usually occur in very young orogenic belts where rock of high density are forced to the crust of the Earth, often in hot springs or other volcanic regions.^[21]

Beginning in 1558, with the invention of the patio process to extract silver from ore using mercury, mercury became an essential resource in the economy of Spain and its American colonies. Sony VAIO VGN-SR41M/P Battery

Mercury was used to extract silver from the lucrative mines in New Spain and Peru. Initially, the Spanish Crown's mines in Almaden in Southern Spain supplied all the mercury for the colonies.^[22]Mercury deposits were discovered in the New World, and more than 100,000 tons of mercury were mined from the region of Huancavelica, Peru, over the course of three centuries following the discovery of deposits there in 1563. Sony VAIO VGN-SR41M/S Battery

The patio process and later pan amalgamation process continued to create great demand for mercury to treat silver ores until the late 19th century.^[23]

Former mines in Italy, the United States and Mexico which once produced a large proportion of the world supply have now been completely mined out or, in the case of Slovenia (Idrija) and Spain (Almadén), shut down due to the fall of the price of mercury. Sony VAIO VGN-SR49VN/H Battery

Nevada's McDermitt Mine, the last mercury mine in the United States, closed in 1992. The price of mercury has been highly volatile over the years and in 2006 was $650 per 76-pound (34.46 kg) flask.^[24]

Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction isSony VAIO VGN-SR51B/P Battery

HgS + O₂ ? Hg + SO₂

In 2005, China was the top producer of mercury with almost two-thirds global share followed by Kyrgyzstan.^[25] Several other countries are believed to have unrecorded production of mercury from copper electrowinning processes and by recovery from effluents. Sony VAIO VGN-SR51B/S Battery

Because of the high toxicity of mercury, both the mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning.^[26] In China, prison labor was used by a private mining company as recently as the 1950s to create new cinnabar mercury mines. Sony VAIO VGN-SR51MF Battery

Thousands of prisoners were used by the Luo Xi mining company to establish new tunnels.^[27] In addition, worker health in functioning mines is at high risk.

The European Union directive calling for compact fluorescent bulbs to be made mandatory by 2012 has encouraged China to re-open deadly cinnabar mines to obtain the mercury required for CFL bulb manufacture. Sony VAIO VGN-SR51MF/P Battery

As a result, environmental dangers have been a concern, particularly in the southern cities of Foshan and Guangzhou, and in the Guizhou province in the south west.^[27]

Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines. Sony VAIO VGN-SR51MF/S Battery

Water run-off from such sites is a recognized source of ecological damage. Former mercury mines may be suited for constructive re-use. For example, in 1976 Santa Clara County, California purchased the historic Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.^[28] Sony VAIO VGN-SR51MF/W Battery

Chemistry

Mercury exists in two main oxidation states, I and II. Higher oxidation states are unimportant, but have been detected, e.g., mercury(IV) fluoride (HgF₄) but only under extraordinary conditions.^[29] Sony VAIO VGN-SR51MR Battery

Compounds of mercury(I)

Different from its lighter neighbors, cadmium and zinc, mercury forms simple stable compounds with metal-metal bonds. The mercury(I) compounds are diamagnetic and feature the dimeric cation, Hg2+
2. Stable derivatives include the chloride and nitrate. Sony VAIO VGN-SR59VG Battery

Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to Hg²⁺ and elemental mercury.^[30] Mercury(I) chloride, a colorless solid also known as calomel, is really the compound with the formula Hg₂Cl₂, with the connectivity Cl-Hg-Hg-Cl. Sony VAIO VGN-SR59VG/H Battery

It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation.

Indicative of its tendency to bond to itself, mercury forms mercury polycations, which consist of linear chains of mercury centers, capped with a positive charge. One example is Hg₃²⁺(AsF₆^–)₂.^[31] Sony VAIO VGN-SR70B/S Battery

Compounds of mercury(II)

Mercury(II) is the most common oxidation state and is the main one in nature as well. All four mercuric halides are known. The form tetrahedral complexes with other ligands but the halides adopt linear coordination geometry, somewhat like Ag⁺ does. Sony VAIO VGN-SR72B/P Battery

Best known is mercury(II) chloride, an easily sublimating white solid. HgCl₂forms coordination complexes that are typically tetrahedral, e.g. HgCl₄^2–.

Mercury(II) oxide, the main oxide of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. Sony VAIO VGN-SR72B/S Battery

It reverts to the elements upon heating near 400 °C, as was demonstrated by Priestly in an early synthesis of pure oxygen.^[7]Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver.

Being a soft metal, mercury forms very stable derivatives with the heavier chalcogens. Sony VAIO VGN-SR73JB/S Battery

Preeminent is mercury(II) sulfide, HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermillion. Like ZnS, HgS crystallizes in two forms, the reddish cubic form and the black zinc blende form.^[4] Mercury(II) selenide (HgSe) and mercury(II) telluride (HgTe) are also known, Sony VAIO VGN-SR74FB/S Battery

these as well as various derivatives, e.g. mercury cadmium telluride and mercury zinc telluridebeing semiconductors useful as infrared detectormaterials.^[32]

Mercury(II) salts form a variety of complex derivatives with ammonia. These include Millon's base (Hg₂N⁺), the one-dimensional polymer (salts of HgNH₂⁺)_n), and "fusible white precipitate" or [Hg(NH₃)₂]Cl₂. Sony VAIO VGN-SR90FS Battery

Known as Nessler's reagent, potassium tetraiodomercurate(II) (HgI₄^2–) is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon's base.

Mercury fulminate, (a detonator widely used in explosives);^[4] Sony VAIO VGN-SR90NS Battery

Compounds of mercury(IV)

Mercury(IV) is the rarest oxidation state of mercury which is known to exist. The only known mercury(IV) compound is mercury(IV) fluoride.

Organomercury compounds

Organic mercury compounds are historically important but are of little industrial value in the western world. Sony VAIO VGN-SR90S Battery

Mercury(II) salts are a rare examples of simple metal complexes that react directly with aromatic rings. Organomercury compounds are always divalent and usually two-coordinate and linear geometry. Unlike organocadmium and organozinc compounds, organomercury compounds do not react with water. Sony VAIO VGN-SR90US Battery

They usually have the formula HgR₂, which are often volatile, or HgRX, which are often solids, where R is aryl or alkyl and X is usually halide or acetate. Methylmercury, a generic term for compounds with the formula CH₃HgX is a dangerous family of compounds that is found in some a polluted water.^[33] They arise by a process known as biomethylation. Sony VAIO VGN-SR91NS Battery

Applications

Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some thermometers, especially ones which are used to measure high temperatures. Sony VAIO VGN-SR91PS Battery

A still increasing amount is used as gaseous mercury in fluorescent lamps, while most of the other applications are slowly phased out due to health and safety regulations and is in some applications replaced with less toxic but considerably more expensive Galinstan alloy. Sony VAIO VGN-SR91S Battery

Medicine

Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood. The element mercury is an ingredient in dental amalgams. Sony VAIO VGN-SR91US Battery

Thiomersal (called Thimerosal in the United States) is an organic compound used as a preservative in vaccines, though this use is in decline.^[34] Another mercury compound Merbromin (Mercurochrome) is a topical antiseptic used for minor cuts and scrapes is still in use in some countries. Sony VAIO VGN-SR92NS Battery

Since the 1930s some vaccines have contained the preservative thiomersal, which is metabolized or degraded to ethyl mercury. Although it was widely speculated that this mercury-based preservative can cause or trigger autism in children, scientific studies showed no evidence supporting any such link.^[35] Sony VAIO VGN-SR92PS Battery

Nevertheless thiomersal has been removed from or reduced to trace amounts in all U.S. vaccines recommended for children 6 years of age and under, with the exception of inactivated influenza vaccine.^[36]

Mercury in the form of one of its common ores, cinnabar, is used in various traditional medicines, especially in traditional Chinese medicine. Sony VAIO VGN-SR92S Battery

Review of its safety has found cinnabar can lead to significant mercury intoxication when heated, consumed in overdoseor taken long term, and can have adverse effects at therapeutic doses, though this is typically reversible at therapeutic doses. Although this form of mercury appears less toxic than others, its use in traditional Chinese medicine has not yet been justified as the therapeutic basis for the use of cinnabar is not clear.^[37] Sony VAIO VGN-SR92US Battery

Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Thermometersandsphygmomanometers containing mercury were invented in the early 18th and late 19th centuries, respectively. In the early 21st century, their use is declining and has been banned in some countries, states and medical institutions. Sony VAIO VGN-SR93DS Battery

In 2002, the U.S. Senatepassed legislation to phase out the sale of non-prescription mercury thermometers. In 2003, Washington and Maine became the first states to ban mercury blood pressure devices.^[38] Mercury compounds are found in some over-the-counter drugs, including topicalantiseptics, stimulant laxatives, diaper-rash ointment, eye drops, and nasal sprays. Sony VAIO VGN-SR93JS Batery

The FDA has "inadequate data to establish general recognition of the safety and effectiveness", of the mercury ingredients in these products.^[39] Mercury is still used in some diuretics, although substitutes now exist for most therapeutic uses. Sony VAIO VGN-SR93PS Batttery

Production of chlorine and caustic soda

Chlorine is produced from sodium chloride (common salt, NaCl) using electrolysis to separate the metallic sodium from the chlorine gas. Usually the salt is dissolved in water to produce a brine. Sony VAIO VGN-SR93YS Battery

By-products of any such chloralkali process are hydrogen (H₂) andsodium hydroxide (NaOH), which is commonly called caustic soda or lye. By far the largest use of mercury^[40][41] in the late 20th century was in the mercury cell process (also called the Castner-Kellner process) where metallic sodium is formed as an amalgam at acathode made from mercury; Sony VAIO VGN-SR94FS Battery

this sodium is then reacted with water to produce sodium hydroxide.^[42] Many of the industrial mercury releases of the 20th century came from this process, although modern plants claimed to be safe in this regard.^[41] After about 1985, all new chloralkali production facilities that were built in the United States used either membrane cell or diaphragm cell technologies to produce chlorine. Sony VAIO VGN-SR94GS Battery

Laboratory uses

Some medical thermometers, especially those for high temperatures, are filled with mercury; however, they are gradually disappearing. In the United States, non-prescription sale of mercury fever thermometers has been banned since 2003.^[43] Sony VAIO VGN-SR94HS Battery

Mercury is also found in liquid mirror telescopes. The mirror is formed by rotating liquid mercury on a disk, the parabolic form of the liquid thus formed reflecting and focusing incident light. Such telescopes are cheaper than conventional large mirror telescopes by up to a factor of 100, but the mirror cannot be tilted and always points straight up. Sony VAIO VGN-SR94VS Battery

Liquid mercury is a part of popular secondary reference electrode (called the calomel electrode) in electrochemistry as an alternative to the standard hydrogen electrode. The calomel electrode is used to work out the electrode potential of half cells.^[47]Last, but not least, the triple point of mercury, ?38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90).^[4] Sony VAIO VGN-SZ35B/B Battery

Niche uses

Gaseous mercury is used in mercury-vapor lamps and some "neon sign" type advertising signs and fluorescent lamps. Those low-pressure lamps emit very spectrally narrow lines, which are traditionally used in optical spectroscopy for calibration of spectral position. Sony VAIO VGN-SZ54B/B Battery

Commercial calibration lamps are sold for this purpose; however simply reflecting some of the fluorescent-lamp ceiling light into a spectrometer is a common calibration practice.^[48] Gaseous mercury is also found in some electron tubes, including ignitrons, thyratrons, and mercury arc rectifiers.^[49] Sony VAIO VGN-SZ55B/B Battery

It is also used in specialist medical care lamps for skin tanning and disinfection (see pictures).^[50] Gaseous mercury is added to cold cathode argon-filled lamps to increase the ionization andelectrical conductivity. An argon filled lamp without mercury will have dull spots and will fail to light correctly. Sony VAIO VGN-SZ55GN/B Battery

Lighting containing mercury can be bombarded/oven pumped only once. When added to neon filled tubes the light produced will be inconsistent red/blue spots until the initial burning-in process is completed; eventually it will light a consistent dull off-blue color.^[51] Sony VAIO VGN-SZ56 Battery

Cosmetics

Mercury, as thiomersal, is widely used in the manufacture of mascara. In 2008, Minnesota became the first state in the US to ban intentionally added mercury in cosmetics, giving it a tougher standard than the federal government.^[52] Sony VAIO VGN-SZ561N Battery

A study in geometric mean urine mercury concentration identified a previously unrecognized source of exposure (skin care products) to inorganic mercury among New York City residents. Population-based biomonitoring also showed that mercury concentration levels are higher in consumers of seafood and fish meals.^[53] Sony VAIO VGN-SZ562N Battery

Historic uses

Many historic applications made use of the peculiar physical properties of mercury, especially as a dense liquid and a liquid metal:

In Islamic Spain, it was used for filling decorative pools. Later, the American artist Alexander Calder built a mercury fountainfor the Spanish Pavilion at the 1937 World Exhibition in Paris. Sony VAIO VGN-SZ57N Battery

• The fountain is now on display at the Fundació Joan Miróin Barcelona.^[54]

Mercury was used inside wobbler lures. Its heavy, liquid form made it useful since the lures made an attractive irregular movement when the mercury moved inside the plug. Sony VAIO VGN-SZ58GN Battery

• Such use was stopped due to environmental concerns, but illegal preparation of modern fishing plugs has occurred.


• The Fresnel lenses of old lighthouses used to float and rotate in a bath of mercury which acted like a bearing.^[55]

Mercury sphygmomanometers (blood pressure meter), barometers, diffusion pumps, coulometers, and many other laboratory instruments. Sony VAIO VGN-SZ58GN/C Battery

• As an opaque liquid with a high density and a nearly linear thermal expansion, it is ideal for this role.^[56]

As an electrically conductive liquid, it was used in mercury switches (including home mercury light switches installed prior to 1970), tilt switches used in old fire detectors, and tilt switches in many modern home thermostats,^[57] Sony VAIO VGN-SZ58N Battery

• Owing to its acoustic properties, mercury was used as the propagation medium in delay line memory devices used in early digital computers of the mid-20th century.

Experimental mercury vapor turbines were installed to increase the efficiency of fossil-fuel electrical power plants.^[58] Sony VAIO VGN-SZ61MN/B Battery

The South Meadow power plant in Hartford, CT employed mercury as its working fluid, in a binary configuration with a secondary water circuit, or a number of years starting in the late 1920s in a drive to improve plant efficiency. Several other plants were built, including the Schiller Station in Portsmouth, NH, which went online in 1950. Sony VAIO VGN-SZ61VN/X Battery

• The idea did not catch on industry-wide due to the weight and toxicity of mercury, as well as the advent of supercritical steam plants in later years.^[59][60]

Similarly, liquid mercury was used as a coolant for some nuclear reactors; however, sodium is proposed for reactors cooled with liquid metal, because the high density of mercury requires much more energy to circulate as coolant.^[61] Sony VAIO VGN-SZ61WN/C Battery

Mercury was a propellant for early ion engines in electric space propulsion systems. Advantages were mercury's high molecular weight, low ionization energy, low dual-ionization energy, high liquid density and liquid storability at room temperature. Sony VAIO VGN-SZ640N/B Battery

Disadvantages were concerns regarding environmental impact associated with ground testing and concerns about eventual cooling and condensation of some of the propellant on the spacecraft in long-duration operations. The first spaceflight to use electric propulsion was a mercury-fueled ion thruster developed by NASA Lewis and flown on the Space Electric Rocket Test "SERT-1" spacecraft launched by NASA at its Wallops Flight Facility in 1964. Sony VAIO VGN-SZ645P3 Battery

The SERT-1 flight was followed up by the SERT-2 flight in 1970. Mercury and caesium were preferred propellants for ion engines until Hughes Research Laboratory performed studies finding xenon gas to be a suitable replacement. Xenon is now the preferred propellant for ion engines as it has a high molecular weightSony VAIO VGN-SZ650N/C Battery

• , little or no reactivity due to its noble gas nature, and has a high liquid density under mild cryogenic storage.^[62][63]


• Mercury has been used to produce liquid mirror telescopes.^[64]

Others applications made use of the chemical properties of mercury: Sony VAIO VGN-SZ660N/C Battery

Mercury was used for preserving wood, developing daguerreotypes, silvering mirrors, anti-fouling paints (discontinued in 1990), herbicides (discontinued in 1995), handheld maze games, cleaning, and road leveling devices in cars. Mercury compounds have been used in antiseptics, laxatives, antidepressants, and in antisyphilitics. Sony VAIO VGN-SZ670N/C Battery

• It was allegedly used by allied spies to sabotage Luftwaffe planes: a mercury paste was applied to bare aluminium, causing the metal to rapidly corrode; this would cause structural failures.^[65]

Chloralkali process: The largest industrial use of mercury during the 20th century was in electrolysis for separating chlorine and sodium from brine; Sony VAIO VGN-SZ680ND Battery

mercury being the anode of the Castner-Kellner process. The chlorine was used for bleaching paper (hence the location of many of these plants near paper mills) while the sodium was used to make sodium hydroxide for soaps and other cleaning products. This usage has largely been discontinued, replaced with other technologies that utilize membrane cells.^[66] Sony VAIO VGN-SZ691N/X Battery

• As electrodes in some types of electrolysis, batteries (mercury cells), sodium hydroxide and chlorine production, handheld games, catalysts, insecticides.


• Mercury was once used as a gun barrel bore cleaner.^[67][68]

From the mid-18th to the mid-19th centuries, a process called "carroting" was used in the making of felt hats. Sony VAIO VGN-SZ71E/B Battery

Animal skins were rinsed in an orange solution (the term "carroting" arose from this color) of the mercury compound mercuric nitrate, Hg(NO₃)₂·2H₂O.^[69] This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. Sony VAIO VGN-SZ71VN/X Battery

The United States Public Health Service banned the use of mercury in the felt industry in December 1941. The psychological symptoms associated with mercury poisoning are said by some to have inspired the phrase "mad as a hatter". Sony VAIO VGN-SZ71WN/C Battery

• Lewis Carroll's "Mad Hatter" in his book Alice's Adventures in Wonderland was a play on words based on the older phrase, but the character himself does not exhibit symptoms of mercury poisoning.^[70]

Gold and silver mining. Historically, mercury was used extensively in hydraulic gold mining in order to help the gold to sink through the flowing water-gravel mixture. Sony VAIO VGN-SZ74B/B Battery

Thin mercury particles may form mercury-gold amalgam and therefore increase the gold recovery rates.^[4] Large-scale use of mercury stopped in the 1960s. However, mercury is still used in small scale, often clandestine, gold prospecting. It is estimated that 45,000 metric tons of mercury used in California forplacer mininghave not been recovered.^[71] Mercury was also used in silver mining.^[72] Sony VAIO VGN-SZ750N/C Battery

Historic medicinal uses

Mercury(I) chloride (also known as calomel or mercurous chloride) has been used in traditional medicine as a diuretic, topical disinfectant, and laxative.Mercury(II) chloride (also known as mercuric chloride or corrosive sublimate) Sony VAIO VGN-SZ75B/B Battery

was once used to treat syphilis (along with other mercury compounds), although it is so toxic that sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat.^[73] It is also used as a disinfectant. Blue mass, a pill or syrup in which mercury is the main ingredient, Sony VAIO VGN-SZ76 Battery

was prescribed throughout the 19th century for numerous conditions including constipation, depression, child-bearing and toothaches.^[74] In the early 20th century, mercury was administered to children yearly as a laxative and dewormer, and it was used in teething powders for infants. Sony VAIO VGN-SZ770N/C Battery

The mercury-containing organohalide merbromin (sometimes sold as Mercurochrome) is still widely used but has been banned in some countries such as the U.S.^[75]

Toxicity and safety

Mercury and most of its compounds are extremely toxic and must be handled with care; Sony VAIO VGN-SZ77N Battery

in cases of spills involving mercury (such as from certainthermometers or fluorescent light bulbs), specific cleaning procedures are used to avoid exposure and contain the spill.^[76] Protocols call for physically merging smaller droplets on hard surfaces, combining them into a single larger pool for easier removal with an eyedropper, or for gently pushing the spill into a disposable container. Sony VAIO VGN-SZ780 Battery

Vacuum cleaners and brooms cause greater dispersal of the mercury and should not be used. Afterwards, fine sulfur, zinc, or some other powder that readily forms an amalgam (alloy) with mercury at ordinary temperatures is sprinkled over the area before itself being collected and properly disposed of. Sony VAIO VGN-SZ78N Battery

Cleaning porous surfaces and clothing is not effective at removing all traces of mercury and it is therefore advised to discard these kinds of items should they be exposed to a mercury spill.

Mercury can be inhaled and absorbed through the skin and mucous membranes, so containers of mercury are securely sealed to avoid spills and evaporation. Sony VAIO VGN-SZ791N/X Battery

Heating of mercury, or of compounds of mercury that may decompose when heated, is always carried out with adequate ventilation in order to avoid exposure to mercury vapor. The most toxic forms of mercury are its organic compounds, such as dimethylmercury and methylmercury. Sony VAIO VGN-SZ84NS Battery

However, inorganic compounds, such as cinnabar are also highly toxic by ingestion or inhalation.^[77] Mercury can cause both chronic and acute poisoning.

Releases in the environment

Preindustrial deposition rates of mercury from the atmosphere may be about 4 ng /(1 L of ice deposit). Sony VAIO VGN-SZ84PS Battery

Although that can be considered a natural level of exposure, regional or global sources have significant effects. Volcanic eruptions can increase the atmospheric source by 4–6 times.^[78]

Natural sources, such as volcanoes, are responsible for approximately half of atmospheric mercury emissions. Sony VAIO VGN-SZ84S Battery

The human-generated half can be divided into the following estimated percentages:^[79][80][81]

65% from stationary combustion, of which coal-fired power plants are the largest aggregate source (40% of U.S. mercury emissions in 1999). This includes power plants fueled with gas where the mercury has not been removed. Sony VAIO VGN-SZ84US Battery

• Emissions from coal combustion are between one and two orders of magnitude higher than emissions from oil combustion, depending on the country.^[79]

11% from gold production. The three largest point sources for mercury emissions in the U.S. are the three largest gold mines. Sony VAIO VGN-SZ85NS Battery

• Hydrogeochemical release of mercury from gold-mine tailings has been accounted as a significant source of atmospheric mercury in eastern Canada.^[82]


• 6.8% from non-ferrous metal production, typically smelters.

6.4% from cement production. Sony VAIO VGN-SZ85S Battery

• 3.0% from waste disposal, including municipal and hazardous waste, crematoria, and sewage sludge incineration. This is a significant underestimate due to limited information, and is likely to be off by a factor of two to five.

3.0% from caustic soda production. Sony VAIO VGN-SZ85US Battery

• 1.4% from pig iron and steel production.


• 1.1% from mercury production, mainly for batteries.


• 2.0% from other sources.

The above percentages are estimates of the global human-caused mercury emissions in 2000, excluding biomass burning, an important source in some regions.^[79] Sony VAIO VGN-SZ94NS Battery

Current atmospheric mercury contamination in outdoor urban air is (0.01–0.02 µg/m³) indoor concentrations are significantly elevated over outdoor concentrations, in the range 0.0065–0.523 µg/m³ (average 0.069 µg/m³).^[83]

Mercury also enters into the environment through the improper disposal (e.g., land filling, incineration) of certain products. Sony VAIO VGN-SZ94PS Battery

Products containing mercury include: auto parts, batteries, fluorescent bulbs, medical products, thermometers, and thermostats.^[84] Due to health concerns (see below), toxics use reduction efforts are cutting back or eliminating mercury in such products. For example, most thermometers now use pigmented alcohol instead of mercury, and galinstan alloy thermometers are also an option. Sony VAIO VGN-SZ94S Battery

Mercury thermometers are still occasionally used in the medical field because they are more accurate than alcohol thermometers, though both are commonly being replaced by electronic thermometers and less commonly by galinstan thermometers. Mercury thermometers are still widely used for certain scientific applications because of their greater accuracy and working range. Sony VAIO VGN-SZ94US Battery

The United States Clean Air Act, passed in 1990, put mercury on a list of toxic pollutants that need to be controlled to the greatest possible extent. Thus, industries that release high concentrations of mercury into the environment agreed to install maximum achievable control technologies (MACT). Sony VAIO VGN-SZ95NS Battery

In March 2005 EPA rule^[85] added power plants to the list of sources that should be controlled and a national cap and trade rule was issued. States were given until November 2006 to impose stricter controls, and several States are doing so. The rule was being subjected to legal challenges from several States in 2005 and decision was made in 2008. Sony VAIO VGN-SZ95S Battery

The Clean Air Mercury Rule was struck down by a Federal Appeals Court on February 8, 2008. The rule was deemed not sufficient to protect the health of persons living near coal-fired power plants. The court opinion cited the negative impact on human health from coal-fired power plants' mercury emissions documented in the EPA Study Report to Congress of 1998.^[86] Sony VAIO VGN-SZ95US Battery

Historically, one of the largest releases was from the Colex plant, a lithium-isotope separation plant at Oak Ridge. The plant operated in the 1950s and 1960s. Records are incomplete and unclear, but government commissions have estimated that some two million pounds of mercury are unaccounted for.^[87] Sony VAIO VGN-TZ121 Battery

A serious industrial disasters was the dumping of mercury compounds into Minamata Bay, Japan. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease.^[88] Sony VAIO VGN-TZ13 Battery

Occupational exposure

Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization, OSHA, and NIOSH all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Sony VAIO VGN-TZ130N/B Battery

Environmental releases and disposal of mercury are regulated in the U.S. primarily by the United States Environmental Protection Agency.

Case control studies have shown effects such as tremors, impaired cognitive skills, and sleep disturbance in workers with chronic exposure to mercury vapor even at low concentrations in the range 0.7–42 ?g/m³.^[89][90Sony VAIO VGN-TZ131 Battery

^] A study has shown that acute exposure (4 – 8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m³resulted in chest pain, dyspnea, cough, hemoptysis, impairment of pulmonary function, and evidence of interstitial pneumonitis.^[91] Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency. Sony VAIO VGN-TZ132/N Battery

Occupational exposure has resulted in broad-ranging functional disturbance, including erethism, irritability, excitability, excessive shyness, and insomnia. With continuing exposure, a fine tremor develops and may escalate to violent muscular spasms. Tremor initially involves the hands and later spreads to the eyelids, lips, and tongue. Sony VAIO VGN-TZ132N Battery

Long-term, low-level exposure has been associated with more subtle symptoms of erethism, including fatigue, irritability, loss of memory, vivid dreams and depression.^[92][93]

Treatment

Research on the treatment of mercury poisoning is limited. Currently available drugs for acute mercurial poisoning include chelators N-acetyl-D, L-penicillamine(NAP), Sony VAIO VGN-TZ150N/B Battery

British Anti-Lewisite (BAL), 2,3-dimercapto-1-propanesulfonic acid (DMPS), and dimercaptosuccinic acid (DMSA). In one small study including 11 construction workers exposed to elemental mercury, patients were treated with DMSA and NAP.^[94] Chelation therapy with both drugs resulted in the mobilization of a small fraction of the total estimated body mercury. Sony VAIO VGN-TZ150N/N Battery

DMSA was able to increase the excretion of mercury to a greater extent than NAP.^[95]

Fish

Fish and shellfish have a natural tendency to concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. Species of fish that are high on the food chain, such as shark, swordfish, king mackerel, albacore tuna, and tilefish contain higher concentrations of mercury than others. Sony VAIO VGN-TZ160CB Battery

As mercury and methylmercury are fat soluble, they primarily accumulate in the viscera, although they are also found throughout the muscle tissue.^[96] When this fish is consumed by a predator, the mercury level is accumulated. Since fish are less efficient at depurating than accumulating methylmercury, fish-tissue concentrations increase over time. Sony VAIO VGN-TZ160N/B Battery

Thus species that are high on the food chain amass body burdens of mercury that can be ten times higher than the species they consume. This process is called biomagnification. Mercury poisoning happened this way in Minamata, Japan, now called Minamata disease.

Regulations

In the United States, the Environmental Protection Agency is charged with regulating and managing mercury contamination. Sony VAIO VGN-TZ16GN/B Battery

Several laws give the EPA this authority, including the Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act, and the Safe Drinking Water Act. Additionally, the Mercury-Containing and Rechargeable Battery Management Act, passed in 1996, phases out the use of mercury in batteries, and provides for the efficient and cost-effective disposal of many types of used batteries.^[97] Sony VAIO VGN-TZ16N Battery

North America contributed approximately 11% of the total global anthropogenic mercury emissions in 1995.^[98]

In the European Union, the directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (see RoHS) bans mercury from certain electrical and electronic products, Sony VAIO VGN-TZ16N/B Battery

and limits the amount of mercury in other products to less than 1000 ppm.^[99] There are restrictions for mercury concentration in packaging (the limit is 100 ppm for sum of mercury, lead, hexavalent chromium and cadmium) and batteries (the limit is 5 ppm).^[100] In July 2007, the European Union also banned mercury in non-electrical measuring devices, such as thermometers and barometers. Sony VAIO VGN-TZ17/N Battery

The ban applies to new devices only, and contains exemptions for the health care sector and a two-year grace period for manufacturers of barometers. ^[101]

Norway enacted a total ban on the use of mercury in the manufacturing and import/export of mercury products, effective January 1, 2008.^[102] Sony VAIO VGN-TZ170N/B Battery

In 2002, several lakes in Norway were found to have a poor state of mercury pollution, with an excess of 1 mg/g of mercury in their sediment. Sony VAIO VGN-TZ170N/N Battery,Sony VAIO VGN-TZ17GN/B Battery,Sony VAIO VGN-TZ17N Battery,Sony VAIO VGN-TZ18/N Battery,Sony VAIO VGN-TZ180N/RC Battery,Sony VAIO VGN-TZ185N/WC Battery