Gold

Gold is a chemical element in the periodic table that has the symbol Au (L. aurum) and atomic number 79. A soft, shiny, yellow, dense, malleable, ductile (trivalent and univalent) transition metal, gold does not react with most chemicals but is attacked by chlorine, fluorine and aqua regia. The metal occurs as nuggets of gold, or grains of gold in rocks and in alluvial deposits and is one of the coinage metals.

Gold

Gold is a chemical element in the periodic table that has the symbol Au (L. aurum) and atomic number 79. A soft, shiny, yellow, dense, malleable, ductile (trivalent and univalent) transition metal, gold does not react with most chemicals but is attacked by chlorine, fluorine and aqua regia. The metal occurs as nuggets of gold, or grains of gold in rocks and in alluvial deposits and is one of the coinage metals.

Gold is used as a monetary standard for the International Monetary Fund (IMF). For millenia, it has been used as money by many nations and gold is also used in jewelry, dentistry, and in electronics. Gold's ISO currency code is XAU.

Notable characteristics of Gold

Gold is a metallic element with a characteristic yellow color, but can also be black or ruby when finely divided, while colloidal solutions are intensely colored and often purple. These colors are the result of gold's plasmon frequency lying in the visible range, which causes red and yellow light to be reflected and blue light to be absorbed. Gold is one of only three metals which have an actual easily-identifiable color; the other two are copper, which is red, and caesium, which has a pale golden color.

Gold is the most malleable and ductile metal known; a single gram of gold can be beaten into a sheet of one square meter, or an ounce into 300 square feet. A soft metal, gold will readily form alloys with many other metals. This can be done to increase its strength, or create several exotic colors, sold for instance in the western United States to the tourist trade as "Black Hills" gold. Adding copper to gold yields a redder metal, iron green, aluminium purple, platinum metals white, and natural bismuth together with silver alloys produce black. Native gold contains usually eight to ten per cent silver, but often much more alloys of gold with a silver content over 20% are called electrum. As the amount of silver increases, the color becomes whiter and the specific gravity lower.

Gold is a good conductor of heat and electricity, and is not affected by air and most reagents. Heat, moisture, oxygen, and most corrosive agents have very little chemical effect on gold, making it well-suited for use in coins and jewelry; conversely, halogens will chemically alter gold, and aqua regia dissolves gold.

Common oxidation states of gold include +1 (gold(I) or aurous compounds) and +3 (gold(III) or auric compounds). Gold ions in solution are readily reduced and precipitated out as gold metal by the addition of virtually any other metal as the reducing agent. The added metal is oxidized and dissolves allowing the gold to be displaced from solution and be recovered as a solid precipitate.

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

Applications for Gold

Pure gold is too soft for ordinary use and is hardened by alloying with silver, copper, and other metals. Gold and its many alloys are most often used in jewelry, coinage and as a standard for monetary exchange in many countries. Because of golds' high electrical conductivity and resistance to corrosion and other desirable combinations of physical and chemical properties, gold also emerged in the late 20th century as an essential industrial metal.

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

Gold History

Gold (Sanskrit jval, Greek ???s?? [khrusos], Latin aurum for "shining dawn", Anglo-Saxon gold, Chinese ? [jin]) has been known and highly valued since prehistoric times. Gold may have been the first metal used by humans and was valued for ornamentation and rituals. Egyptian hieroglyphs from as early as 2600 BC describe gold, which king Tushratta of the Mitanni claimed was as "common as dust" in Egypt. Egypt and Nubia had the resources to make them major gold-producing areas for much of history. Gold is also mentioned several times in the Old Testament. The south-east corner of the Black Sea was famed for its gold. Exploitation of gold is said to date from the time of Midas, and this gold was important in the establishment of what is probably the world's earliest coinage in Lydia between 643 and 630 BC.

The European exploration of the Americas was fueled in no small part by reports of the gold ornaments displayed in great profusion by Native American peoples, especially in Central America, Peru, and Colombia.

Gold has long been considered one of the most precious metals, and its value has been used as the standard for many currencies (known as the gold standard) in history. Gold has been used as a symbol for purity, value, royalty, and particularly roles that combine these properties.

Gold in antiquity was relatively easy to obtain geologically; however, 75% of all gold ever produced has been extracted since 1910. It has been estimated that all the gold in the world that has ever been refined would form a single cube 20 m (66 ft) a side.

The primary goal of the alchemists was to produce gold from other substances, such as lead presumably by the interaction with a mythical substance called the philosopher's stone. Although they never succeeded in this attempt, the alchemists promoted an interest in what can be done with substances, and this laid a foundation for today's chemistry. Their symbol for gold was the circle with a point at its center (?), which was also the astrological symbol, the Egyptian hieroglyph and the ancient Chinese character for the Sun (now ?). For modern attempts to produce artificial gold, see gold synthesis.

During the 19th century gold rushes occurred whenever large gold deposits were discovered, including the California Gold Rush, Colorado, Otago, Australia, Witwatersrand, Black Hills, and Klondike gold rushes.

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

Gold Value

Like other precious metals, gold is measured by troy weight and by grams. When it is alloyed with other metals the term carat or karat is used to indicate the amount of gold present, with 24 carats being pure gold and lower ratings proportionally less. The purity of a gold bar can also be expressed as a decimal figure ranging from 0 to 1, known as the millesimal fineness, such as 0.995.

The price of gold is determined on the open market, but a procedure known as the Gold Fixing in London, originating in 1919, provides a twice-daily benchmark figure to the gold industry.

Historically gold was used to back currency in an economic system known as the gold standard in which one unit of currency was equivalent to a certain weight of gold. As part of this system, governments and central banks attempted to control the price of gold by setting values at which they would exchange it for currency. For a long period the United States government set the price of gold at $20.67 per troy ounce ($664.56/kg) but in 1934 the price of gold was set at $35.00 per troy ounce ($1125.27/kg). By 1961 it was becoming hard to maintain this price, and a pool of US and European banks began to act together to defend the price of gold against market forces.

On March 17, 1968, economic circumstances caused the collapse of the gold pool, and a two-tiered pricing scheme was established whereby gold was still used to settle international accounts at the old $35.00 per troy ounce ($1.13/g) but the price of gold on the private market was allowed to fluctuate; this two-tiered pricing system was abandoned in 1975 when the price of gold was left to find its free-market level. Central banks still hold historical gold reserves as a reserve asset although the level has generally been declining. The largest gold depository in the world is that of the U.S. Federal Reserve Bank, held at Fort Knox.

Since 1968 the price of gold on the open market has ranged widely, with a record high of $850/oz ($27,300/kg) on 21 January 1980, to a low of $252.90/oz ($8,131/kg) on 21 June 1999 (London Fixing). Prices have risen to the $468/oz mark in 2005, due to a depreciation of the US dollar and inflation due to rising energy costs. The price of gold has remained relatively constant in currencies not tied to the US dollar; for example, it has not varied by more than 10% from 330/oz (10,600/kg) or A$560/oz (A$18,000/kg) during this time.

Gold and the money supply

In January 1959 US M3 money supply was $288.8 billion, and the Official Gold Holdings of the United States was then 17'335.1 Tonnes, or about 557 million ounces (there are 32,150.7 Troy Ounces in a Tonne). That means that in 1959, there were $518 in circulation for every ounce of gold reserves held by the USA. Although the theoretical price should then have been $518 per ounce, the actual price, as fixed under the gold standard was only $35 an ounce.

By August 2005, the US M3 money supply had risen to $9'873.9 billion, whilst at the same time the Official Gold Holdings of the United States had fallen to just 8'133.5 Tonnes, or about 261 million Troy Ounces. This means that today, in 2005, there are $37'831 in circulation for every ounce of gold held by the United States.

The above numbers show the falling influence of gold in the monetary system of the world today. Goldbugs believe, or even hope, that one day gold's importance will return as the printing of paper money gets out of control and we end in a hyper-inflationary fiat money collapse.

Restrictions on gold ownership

Because of golds use as a reserve store of value, the possession of gold is sometimes restricted or banned. Within the United States, the private possession of gold except as jewelry and coin collecting was banned between 1933 and 1975. President Franklin D. Roosevelt confiscated gold by Executive Order 6102, and President Richard Nixon closed the gold window by which foreign countries could exchange American dollars for gold at a fixed rate.

Return of a Gold Standard?

In the first few years of the 21st century, reports started to circulate that Malaysia was planning a return to the gold standard -- to issue and use gold dinars as currency in international trade. The purported purpose of this move would be to reduce dependence on the United States dollar as a reserve currency, and to establish a non-debt-backed currency in accord with Islamic law against the charging of interest. Nonetheless, gold dinar currency has not yet emerged.

Gold in investment portfolios

As a tangible investment gold is sometimes held as part of a portfolio because over the long term gold has an extensive history of maintaining its value. It has in the last century gained ground in relation to fiat currencies owing to inflation. Gold becomes particularly desirable in times of extremely weak confidence and during hyperinflation because gold maintains its value even as fiat money becomes worthless. People who enjoy investing in gold are known as goldbugs.

Futures contracts based on gold currently trade on various exchanges around the world. In the US this occurs primarily on COMEX (Commodity Exchange) which is a subsidiary of the New York Mercantile Exchange. Speculation about the future price of gold and other commodities is carried on at COMEX. Recently, gold-based ETFs like GLD have emerged as a more convenient investment vehicle.

Occurrence of Gold

Due to its relative chemical inertness gold is usually found as the native metal or alloy. Occasionally large accumulations of native gold (also known as nuggets) occur but usually gold occurs as minute grains. These grains occur between mineral grain boundries or as inclusions within minerals. Common gold associations are quartz often as veins and sulfide minerals. The most common sulfide associations with gold are pyrite, chalcopyrite, galena, sphalerite, arsenopyrite, stibnite and pyrrhotite. Rarer mineral associations with gold are petzite, calaverite, sylvanite, muthmannite, nagyagite and krennerite.

Gold is widely distributed in the Earth's crust at a background level of 0.03 g/1000 kg (0.03 ppm by weight). Hydrothermal ore deposits of gold occur in metamorphic rocks and igneous rocks; alluvial deposits of gold and placer deposits of gold originate from these sources.

The primary source of gold is usually igneous rocks or surface concentrations. A gold deposit usually needs some form of secondary enrichment to form an economically viable ore deposit: either chemical or physical processes like erosion or solution or more generally metamorphism, which concentrates the gold in sulfide minerals or quartz. There are several primary deposit types, common ones are termed reef or vein. Primary deposits can be weathered and eroded, with most of the gold being transported into stream beds where it congregates with other heavy minerals to form placer deposits. In all these deposits the gold is in its native form. Another important ore type is in sedimentary black shale and limestone deposits containing finely disseminated gold and other platinum group metals.

Gold occurs in sea water at 0.1 to 2 mg/t (0.1 to 2 ppb by weight) depending on sample location.

Production of Gold

Economic gold extraction can be achieved from ore grades as little as 0.5 g/1000 kg (0.5 ppm) on average in large easily mined deposits, typical ore grades in open-pit mines are 15 g/1000 kg (1-5 ppm), ore grades in underground or hard rock mines are usually at least 3 g/1000 kg (3 ppm) on average. Ore grades of 30 g/1000 kg (30 ppm) are usually needed before gold is visible to the naked eye, therefore in most gold mines you will not see any gold. It is claimed, that all the gold that has been mined thorughout the history of mankind could be incorporated in a solid ball with a diameter of 27 metres.

Since the 1880s South Africa has been the source for about two-thirds of the world's gold supply. The city of Johannesburg was built atop the world's greatest gold finds. Gold fields in the Orange Free State and the Transvaal were deep and require the world's deepest mines. The Second Boer War of 18991901 between the British Empire and the white Boers was at least partly over the rights of miners and possession of the gold Wealth in South Africa. Other major producers of gold are Canada, United States and Western Australia. Mines in South Dakota and Nevada supply two-thirds of gold used in the United States. Siberian regions of the USSR also used to be significant in the global gold mining industry. Kolar Gold Fields in India is another example of a city being built on the greatest gold deposits in India. In South America, the controversial project Pascua Lama aims at exploitation of rich gold fields in the high mountains of Atacama, at the border between Chile and Argentina.

The idea of producing gold out of lesser metals or other cheap substances has fascinated people throughout the centuries. Scientists, kings and charlatans obsessed with the secret art of alchemy accidentally invented practically useful materials (e.g. porcelain), while searching in vain for the philosopher's stone, which was supposed to turn mercury into gold. Modern science has since proven the impossibility of making gold from other elements via chemical reactions.

However, it is possible to obtain infinitesimally small amounts of gold by artificial nuclear transformations in particle accelerators. The gold isotopes produced would likely be radioactive. No economically feasible method to manufacture gold artificially has been found or published yet. The possibility of cheap man-made gold would have unforeseen economic and political consequences.

Gold Compounds /Gold Isotopes

Although gold is a noble metal, it can form many compounds, auric chloride (AuCl3) and chlorauric acid (HAuCl4) being the most common. Gold compounds can be aurous (univalent, +1) or auric (trivalent, +3). Gold also can under extreme conditions form a +5 state with fluorine (gold pentafluoride, AuF5), as well as (unusually for a metal), a -1 state. Such compounds containing the Au- anion are called aurides and include caesium auride, CsAu, rubidium auride, RbAu, and tetramethylammonium auride, (CH3)4N+ Au-.

Gold also forms:

  • The AuCl4- ion after dissolving in aqua regia
  • Gold halides (F,Cl,Br,I)
  • Gold chalcogenides (O, S, Se,Te)
  • Gold cluster compounds
  • Gold hydrazide: an olive-green powder, AuN2H3, one of several explosive compounds known archaically as aurum fulminans

There is only one stable isotope of gold, and 18 radioisotopes with Au-195 being the most stable with a half-life of 186 days.

Precautions with Gold

The human body does not absorb gold very well, thus compounds of gold are not normally very toxic. Liver and kidney damage has, however, been reported for up to 50% of arthritis patients treated with gold-containing drugs. Gold used in dentistry is widely regarded as the safest form of restorative material, as well as the most successful.

Gold Symbolism

Gold has been associated with the extremities of utmost evil and great sanctity throughout history. The Golden Calf is a widely-recognised symbol of idolatry and revolt against God; concentration camp guards removed the golden teeth from the mouths of gassed Holocaust victims. In Communist propaganda, the golden pocket watch and its fastening golden chain were the characteristic accessories of the class enemy, the bourgeois and the industrial tycoons.

On the other hand, eminent orators such as John Chrysostom were said to have a mouth of gold with a silver tongue. Gold is associated with notable anniversaries, particularly in a 50 year cycle, such as a golden wedding anniversary, golden jubilee, etc.

Great human achievements are frequently rewarded with gold, in the form of medals and decorations. Winners of races and prizes are usually awarded the gold medal (such as the Olympic Games and the Nobel Prize), while many award statues are depicted in gold (such as the Academy Awards, the Emmy Awards and the British Academy Film Awards).

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 are traditionally made of gold; since it is long-lasting and unaffected by the passage of time, it is considered a suitable material for everyday wear as well as a metaphor for the relationship. In Orthodox Christianity, the wedded couple is adorned with a golden crown during the ceremony, an amalgamation of symbolic rites.

The symbolic value of gold varies wildly around the world, even within geographic regions. For example, gold is quite common in Turkey but considered a most valuable gift in Sicily.

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