Gold is a chemical element with symbol Au (from Latin: aurum) and
atomic number 79, making it one of the higher atomic number elements
that occur naturally. In its purest form, it is a bright, slightly
reddish yellow, dense, soft, malleable, and ductile metal. Chemically,
gold is a transition metal and a group 11 element. It is one of the
least reactive chemical elements and is solid under standard
Gold often occurs in free elemental (native) form, as
nuggets or grains, in rocks, in veins, and in alluvial deposits. It
occurs in a solid solution series with the native element silver (as
electrum) and also naturally alloyed with copper and palladium. Less
commonly, it occurs in minerals as gold compounds, often with
tellurium (gold tellurides).
Gold is resistant to most acids, though it does dissolve in aqua
regia, a mixture of nitric acid and hydrochloric acid, which forms a
soluble tetrachloroaurate anion.
Gold is insoluble in nitric acid,
which dissolves silver and base metals, a property that has long been
used to refine gold and to confirm the presence of gold in metallic
objects, giving rise to the term acid test.
Gold also dissolves in
alkaline solutions of cyanide, which are used in mining and
Gold dissolves in mercury, forming amalgam alloys, but
this is not a chemical reaction.
A relatively rare element, gold is a precious metal that has
been used for coinage, jewelry, and other arts throughout recorded
history. In the past, a gold standard was often implemented as a
monetary policy, but gold coins ceased to be minted as a circulating
currency in the 1930s, and the world gold standard was abandoned for a
fiat currency system after 1976.
A total of 186,700 tonnes of gold exists above ground, as of 2015.
The world consumption of new gold produced is about 50% in jewelry,
40% in investments, and 10% in industry. Gold's high malleability,
ductility, resistance to corrosion and most other chemical reactions,
and conductivity of electricity have led to its continued use in
corrosion resistant electrical connectors in all types of computerized
devices (its chief industrial use).
Gold is also used in infrared
shielding, colored-glass production, gold leafing, and tooth
restoration. Certain gold salts are still used as anti-inflammatories
in medicine. As of 2016, the world's largest gold producer by far was
China with 450 tonnes per year.
2.1 Rare oxidation states
2.2 Medicinal uses
3.1 Celestial origin theories
3.2 Earth's mantle origins
6.1 Mining and prospecting
6.2 Extraction and refining
8 Other applications
10 See also
12 External links
A gold nugget of 5 millimetres (0.20 in) in diameter (bottom) can
be expanded through hammering into a gold foil of about 0.5 square
metres (5.4 sq ft). Toi museum, Japan.
Gold is the most malleable of all metals; a single gram can be beaten
into a sheet of 1 square meter, and an avoirdupois ounce into 300
Gold leaf can be beaten thin enough to become
semi-transparent. The transmitted light appears greenish blue, because
gold strongly reflects yellow and red. Such semi-transparent
sheets also strongly reflect infrared light, making them useful as
infrared (radiant heat) shields in visors of heat-resistant suits, and
in sun-visors for spacesuits.
Gold is a good conductor of heat and
Gold has a density of 19.3 g/cm3, almost identical to that of
tungsten at 19.25 g/cm3; as such, tungsten has been used in
counterfeiting of gold bars, such as by plating a tungsten bar with
gold, or taking an existing gold bar, drilling holes,
and replacing the removed gold with tungsten rods. By comparison,
the density of lead is 11.34 g/cm3, and that of the densest
element, osmium, is 22.588 ± 0.015 g/cm3.
Main article: Colored gold
Different colors of Ag–Au–Cu alloys
Whereas most metals are gray or silvery white, gold is slightly
reddish-yellow. This color is determined by the frequency of
plasma oscillations among the metal's valence electrons, in the
ultraviolet range for most metals but in the visible range for gold
due to relativistic effects affecting the orbitals around gold
atoms. Similar effects impart a golden hue to metallic
Common colored gold alloys include the distinctive eighteen-karat rose
gold created by the addition of copper. Alloys containing palladium or
nickel are also important in commercial jewelry as these produce white
gold alloys. Fourteen-karat gold-copper alloy is nearly identical in
color to certain bronze alloys, and both may be used to produce police
and other badges. White gold alloys can be made with palladium or
nickel. Fourteen- and eighteen-karat gold alloys with silver alone
appear greenish-yellow and are referred to as green gold. Blue gold
can be made by alloying with iron, and purple gold can be made by
alloying with aluminium. Less commonly, addition of manganese,
aluminium, indium and other elements can produce more unusual colors
of gold for various applications.
Colloidal gold, used by electron-microscopists, is red if the
particles are small; larger particles of colloidal gold are blue.
Main article: Isotopes of gold
Gold has only one stable isotope, 197Au, which is also its only
naturally occurring isotope, so gold is both a mononuclidic and
monoisotopic element. Thirty-six radioisotopes have been synthesized
ranging in atomic mass from 169 to 205. The most stable of these is
195Au with a half-life of 186.1 days. The least stable is 171Au, which
decays by proton emission with a half-life of 30 µs. Most of gold's
radioisotopes with atomic masses below 197 decay by some combination
of proton emission, α decay, and β+ decay. The exceptions are 195Au,
which decays by electron capture, and 196Au, which decays most often
by electron capture (93%) with a minor β− decay path (7%). All
of gold's radioisotopes with atomic masses above 197 decay by β−
At least 32 nuclear isomers have also been characterized, ranging in
atomic mass from 170 to 200. Within that range, only 178Au, 180Au,
181Au, 182Au, and 188Au do not have isomers. Gold's most stable isomer
is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer
is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay
paths: β+ decay, isomeric transition, and alpha decay. No other
isomer or isotope of gold has three decay paths.
The production of gold from a more common element, such as lead, has
long been a subject of human inquiry, and the ancient and medieval
discipline of alchemy often focused on it; however, the transmutation
of the chemical elements did not become possible until the
understanding of nuclear physics in the 20th century. The first
synthesis of gold was conducted by Japanese physicist Hantaro Nagaoka,
who synthesized gold from mercury in 1924 by neutron bombardment.
An American team, working without knowledge of Nagaoka's prior study,
conducted the same experiment in 1941, achieving the same result and
showing that the isotopes of gold produced by it were all
Gold can currently be manufactured in a nuclear reactor by irradiation
either of platinum or mercury.
Only the mercury isotope 196Hg, which occurs with a frequency of 0.15%
in natural mercury, can be converted to gold by neutron capture, and
following electron capture-decay into 197Au with slow neutrons. Other
mercury isotopes are converted when irradiated with slow neutrons into
one another, or formed mercury isotopes which beta decay into
Using fast neutrons, the mercury isotope 198Hg, which composes 9.97%
of natural mercury, can be converted by splitting off a neutron and
becoming 197Hg, which then disintegrates to stable gold. This
reaction, however, possesses a smaller activation cross-section and is
feasible only with un-moderated reactors.
It is also possible to eject several neutrons with very high energy
into the other mercury isotopes in order to form 197Hg. However, such
high-energy neutrons can be produced only by particle
Gold(III) chloride solution in water
Although gold is the most noble of the noble metals, it still
forms many diverse compounds. The oxidation state of gold in its
compounds ranges from −1 to +5, but Au(I) and Au(III) dominate its
chemistry. Au(I), referred to as the aurous ion, is the most common
oxidation state with soft ligands such as thioethers, thiolates, and
tertiary phosphines. Au(I) compounds are typically linear. A good
example is Au(CN)2−, which is the soluble form of gold encountered
in mining. The binary gold halides, such as AuCl, form zigzag
polymeric chains, again featuring linear coordination at Au. Most
drugs based on gold are Au(I) derivatives.
Au(III) (auric) is a common oxidation state, and is illustrated by
gold(III) chloride, Au2Cl6. The gold atom centers in Au(III)
complexes, like other d8 compounds, are typically square planar, with
chemical bonds that have both covalent and ionic character.
Gold does not react with oxygen at any temperature and, up to
100 °C, is resistant to attack from ozone.
Some free halogens react with gold.
Gold is strongly attacked by
fluorine at dull-red heat to form gold(III) fluoride. Powdered
gold reacts with chlorine at 180 °C to form AuCl3. Gold
reacts with bromine at 140 °C to form gold(III) bromide, but
reacts only very slowly with iodine to form the monoiodide.
Gold does not react with sulfur directly, but gold(III) sulfide
can be made by passing hydrogen sulfide through a dilute solution of
gold(III) chloride or chlorauric acid.
Gold readily dissolves in mercury at room temperature to form an
amalgam, and forms alloys with many other metals at higher
temperatures. These alloys can be produced to modify the hardness and
other metallurgical properties, to control melting point or to create
Gold reacts with potassium, rubidium, caesium, or tetramethylammonium,
to form the respective auride salts, containing the Au− ion. Caesium
auride is perhaps the most famous.
Gold is unaffected by most acids. It does not react with hydrofluoric,
hydrochloric, hydrobromic, hydriodic, sulfuric, or nitric acid. It
does react with selenic acid, and is dissolved by aqua regia, a 1:3
mixture of nitric acid and hydrochloric acid.
Nitric acid oxidizes the
metal to +3 ions, but only in minute amounts, typically undetectable
in the pure acid because of the chemical equilibrium of the reaction.
However, the ions are removed from the equilibrium by hydrochloric
acid, forming AuCl4− ions, or chloroauric acid, thereby enabling
Gold is similarly unaffected by most bases. It does not react with
aqueous, solid, or molten sodium or potassium hydroxide. It does
however, react with sodium or potassium cyanide under alkaline
conditions when oxygen is present to form soluble complexes.
Common oxidation states of gold include +1 (gold(I) or aurous
compounds) and +3 (gold(III) or auric compounds).
Gold ions in
solution are readily reduced and precipitated as metal by adding any
other metal as the reducing agent. The added metal is oxidized and
dissolves, allowing the gold to be displaced from solution and be
recovered as a solid precipitate.
Rare oxidation states
Less common oxidation states of gold include −1, +2, and +5.
The −1 oxidation state occurs in compounds containing the Au−
anion, called aurides.
Caesium auride (CsAu), for example,
crystallizes in the caesium chloride motif. Other aurides include
those of Rb+, K+, and tetramethylammonium (CH3)4N+.
Gold has the
highest Pauling electronegativity of any metal, with a value of 2.54,
making the auride anion relatively stable.
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 H
4 produces red crystals of gold(II) sulfate, Au2(SO4)2. Originally
thought to be a mixed-valence compound, it has been shown to contain
2 cations, analogous to the better-known mercury(I) ion, Hg2+
2 . A gold(II) complex, the tetraxenonogold(II) cation, which
contains xenon as a ligand, occurs in [AuXe4](Sb2F11)2.
Gold pentafluoride, along with its derivative anion, AuF−
6, and its difluorine complex, gold heptafluoride, is the sole example
of gold(V), the highest verified oxidation state.
Some gold compounds exhibit aurophilic bonding, which describes the
tendency of gold ions to interact at distances that are too long to be
a conventional Au–Au bond but shorter than van der Waals bonding.
The interaction is estimated to be comparable in strength to that of a
Well-defined cluster compounds are numerous. 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).
Medicinal applications of gold and its complexes have a long history
dating back thousands of years. Several gold complexes have been
applied to treat rheumatoid arthritis, the most frequently used are:
aurothiomalate, aurothioglucose, and auranofin. Both gold(I) and
gold(III) compounds have been have been investigated as possible
anti-cancer drugs. For gold(III) complexes, reduction to gold(0/I)
under physiological conditions has to be considered. Stable complexes
can be generated using different types of bi-, tri-, and tetradentate
ligand systems and their high efficacy has been demonstrated in vitro
and in vivo.
Relative sizes of an 860 kg block of gold ore, and the 30 g
of gold that can be extracted from it. Toi gold mine, Japan.
Schematic of a NE (left) to SW (right) cross-section through the
2.020 billion year old Vredefort impact crater in South Africa
and how it distorted the contemporary geological structures. The
present erosion level is shown.
Johannesburg is located where the
Witwatersrand Basin (the yellow layer) is exposed at the "present
surface" line, just inside the crater rim, on the left. Not to scale.
Celestial origin theories
Gold is thought to have been produced in supernova nucleosynthesis,
from the collision of neutron stars, and to have been present in
the dust from which the
Solar System formed. Because the Earth was
molten when it was formed, almost all of the gold present in the early
Earth probably sank into the planetary core. Therefore, most of the
gold that is in the Earth's crust and mantle is thought to have been
delivered to Earth later, by asteroid impacts during the Late Heavy
Bombardment, about 4 billion years ago.
Traditionally, gold is thought to have formed by the r-process (rapid
neutron capture) in supernova nucleosynthesis, but more recently
it has been suggested that gold and other elements heavier than iron
may also be produced in quantity by the r-process in the collision of
neutron stars. In both cases, satellite spectrometers only
indirectly detected the resulting gold: "we have no spectroscopic
evidence that [such] elements have truly been produced," wrote author
Stephan Rosswog. However, in August 2017, the signatures of heavy
elements, including gold, were observed by gravitational wave
detectors and other electromagnetic observatories in the GW170817
neutron star merger event. Current astrophysical models suggest
that single neutron star merger event generated between 3 and 13 Earth
masses of gold.
The asteroid that formed
Vredefort crater 2.020 billion years ago
is often credited with seeding the
Witwatersrand basin in South Africa
with the richest gold deposits on earth. However, the
Witwatersrand rocks were laid down between 700 and
950 million years before the Vredefort impact. These
gold-bearing rocks had furthermore been covered by a thick layer of
Ventersdorp lavas and the Transvaal Supergroup of rocks before the
meteor struck. What the Vredefort impact achieved, however, was to
Witwatersrand basin in such a way that the gold-bearing
rocks were brought to the present erosion surface in Johannesburg, on
the Witwatersrand, just inside the rim of the original 300 km
diameter crater caused by the meteor strike. The discovery of the
deposit in 1886 launched the
Gold Rush. Some 22% of all
the gold that is ascertained to exist today on Earth has been
extracted from these
Earth's mantle origins
In 2017, an international group of scientists, including José María
González Jiménez and Ramón y Cajalan, in cooperation with the
University of Granada
University of Granada and other universities, while researching the
origins of gold, historically established that it "came to the Earth's
surface from the deepest regions of our planet," evidenced by their
Deseado Massif in the Argentinian Patagonia.
On Earth, gold is found in ores in rock formed from the Precambrian
time onward. It most often occurs as a native metal, typically in
a metal solid solution with silver (i.e. as a gold silver alloy). Such
alloys usually have a silver content of 8–10%.
Electrum is elemental
gold with more than 20% silver. Electrum's color runs from
golden-silvery to silvery, dependent upon the silver content. The more
silver, the lower the specific gravity.
Native gold occurs as very small to microscopic particles embedded in
rock, often together with quartz or sulfide minerals such as "Fool's
Gold", which is a pyrite. These are called lode deposits. The
metal in a native state is also found in the form of free flakes,
grains or larger nuggets that have been eroded from rocks and end
up in alluvial deposits called placer deposits. Such free gold is
always richer at the surface of gold-bearing veins[clarification
needed] owing to the oxidation of accompanying minerals followed by
weathering, 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 (see
telluride minerals), and as the rare bismuthide maldonite (Au2Bi) and
antimonide aurostibite (AuSb2).
Gold also occurs in rare alloys with
copper, lead, and mercury: the minerals auricupride (Cu3Au),
novodneprite (AuPb3) and weishanite ((Au, Ag)3Hg2).
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.
Another recent study has claimed water in faults vaporizes during an
earthquake, depositing gold. When an earthquake strikes, it moves
along a fault. Water often lubricates faults, filling in fractures and
jogs. About 6 miles (10 kilometers) below the surface, under
incredible temperatures and pressures, the water carries high
concentrations of carbon dioxide, silica, and gold. During an
earthquake, the fault jog suddenly opens wider. The water inside the
void instantly vaporizes, flashing to steam and forcing silica, which
forms the mineral quartz, and gold out of the fluids and onto nearby
The world's oceans contain gold. Measured concentrations of gold in
the Atlantic and Northeast Pacific are 50–150 femtomol/L or 10–30
parts per quadrillion (about 10–30 g/km3). In general, gold
concentrations for south Atlantic and central Pacific samples are the
same (~50 femtomol/L) but less certain. Mediterranean deep waters
contain slightly higher concentrations of gold (100–150 femtomol/L)
attributed to wind-blown dust and/or rivers. At 10 parts per
quadrillion the Earth's oceans would hold 15,000 tonnes of gold.
These figures are three orders of magnitude less than reported in the
literature prior to 1988, indicating contamination problems with the
A number of people have claimed to be able to economically recover
gold from sea water, but they were either mistaken or acted in an
intentional deception. Prescott Jernegan ran a gold-from-seawater
swindle in the
United States in the 1890s, as did an English fraudster
in the early 1900s.
Fritz Haber did research on the extraction of
gold from sea water in an effort to help pay Germany's reparations
following World War I. Based on the published values of 2 to 64
ppb of gold in seawater a commercially successful extraction seemed
possible. After analysis of 4,000 water samples yielding an average of
0.004 ppb it became clear that extraction would not be possible and he
stopped the project.
Ancient golden Kritonios Crown, funerary or marriage material,
370–360 BC. From a grave in Armento, Campania
Gold artifacts found at the Nahal Kana cave cemetery dated during the
1980s, showed these to be from within the Chalcolithic, and considered
the earliest find from the Levant.
Gold artifacts in the Balkans
also appear from the 4th millennium BC, such as those found in the
Varna Necropolis near Lake Varna in Bulgaria, thought by one source
(La Niece 2009) to be the earliest "well-dated" find of gold
Gold artifacts such as the golden hats and the Nebra
disk appeared in Central Europe from the 2nd millennium BC
The oldest known map of a gold mine was drawn in the 19th Dynasty of
Egypt (1320–1200 BC), whereas the first written reference to
gold was recorded in the 12th Dynasty around 1900 BC. Egyptian
hieroglyphs from as early as 2600 BC describe gold, which King
Tushratta of the
Mitanni claimed was "more plentiful than dirt" in
Egypt and especially
Nubia had the resources to make them
major gold-producing areas for much of history. One of the earliest
known maps, known as the Turin Papyrus Map, shows the plan of a gold
Nubia together with indications of the local geology. The
primitive working methods are described by both
Strabo and Diodorus
Siculus, and included fire-setting. Large mines were also present
Red Sea in what is now Saudi Arabia.
Gold is mentioned in the
Amarna letters numbered 19 and 26
from around the 14th century BC.
The legend of the golden fleece may refer to the use of fleeces to
trap gold dust from placer deposits in the ancient world.
mentioned frequently in the Old Testament, starting with Genesis 2:11
(at Havilah), the story of
The Golden Calf
The Golden Calf and many parts of the
temple including the Menorah and the golden altar. In the New
Testament, it is included with the gifts of the magi in the first
chapters of Matthew. The
Book of Revelation
Book of Revelation 21:21 describes the city
New Jerusalem as having streets "made of pure gold, clear as
crystal". Exploitation of gold in the south-east corner of the Black
Sea 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. 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. One of
their largest mines was at
Las Medulas in León, where seven long
aqueducts enabled them to sluice most of a large alluvial deposit. The
Roşia Montană in
Transylvania were also very large, and
until very recently, still mined by opencast methods. They also
exploited smaller deposits in Britain, such as placer and hard-rock
deposits at Dolaucothi. The various methods they used are well
Pliny the Elder
Pliny the Elder in his encyclopedia Naturalis Historia
written towards the end of the first century AD.
During Mansa Musa's (ruler of the
Mali Empire from 1312 to 1337) hajj
Mecca in 1324, he passed through
Cairo in July 1324, and was
reportedly accompanied by a camel train that included thousands of
people and nearly a hundred camels where he gave away so much gold
that it depressed the price in
Egypt for over a decade, causing high
inflation. A contemporary Arab historian remarked:
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
spent there [...].
— Chihab Al-Umari, Kingdom of Mali
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 Mesoamerica, Peru,
Colombia. The Aztecs regarded gold as the product of the gods, calling
it literally "god excrement" (teocuitlatl in Nahuatl), and after
Moctezuma II was killed, most of this gold was shipped to Spain.
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. Rumors of cities filled with gold fueled legends of El
Gold played a role in western culture, as a cause for desire and of
corruption, as told in children's fables such as
Rumpelstiltskin turns hay into gold for the
peasant's daughter in return for her child when she becomes a
princess—and the stealing of the hen that lays golden eggs in Jack
and the Beanstalk.
The top prize at the
Olympic Games and many other sports competitions
is the gold medal.
75% of the presently accounted for gold has been extracted since 1910.
It has been estimated that the currently known amount of gold
internationally would form a single cube 20 m (66 ft) on a
side (equivalent to 8,000 m3).
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 the philosopher's stone. Although they never
succeeded in this attempt, the alchemists did promote an interest in
systematically finding out what can be done with substances, and this
laid the 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 ancient
Chinese character for the Sun.
Golden treasures have been rumored to be found at various locations,
following tragedies such as the Jewish temple treasures in the
Vatican, following the temple's destruction in 70 AD, a gold stash on
the Titanic, the
Nazi gold train – following World War II.
Dome of the Rock
Dome of the Rock is covered with an ultra-thin golden glassier.
Sikh Golden temple, the Harmandir Sahib, is a building covered
with gold. Similarly the
Wat Phra Kaew
Wat Phra Kaew emerald Buddhist temple (wat)
Thailand has ornamental gold-leafed statues and roofs. Some
European king and queen's crowns were made of gold, and gold was used
for the bridal crown since antiquity. An ancient Talmudic text circa
100 AD describes Rachel, wife of Rabbi Akiva, receiving a "Jerusalem
of Gold" (diadem). A Greek burial crown made of gold was found in a
grave circa 370 BC.
"Gold" is cognate with similar words in many Germanic languages,
Proto-Germanic *gulþą from Proto-Indo-European
*ǵʰelh₃- ("to shine, to gleam; to be yellow or green").
The symbol Au is from the Latin: aurum, the Latin word for "gold".
Proto-Indo-European ancestor of aurum was *h₂é-h₂us-o-,
meaning "glow". This word is derived from the same root
Proto-Indo-European *h₂u̯es- "to dawn") as *h₂éu̯sōs, the
ancestor of the Latin word Aurora, "dawn". This etymological
relationship is presumably behind the frequent claim in scientific
publications that aurum meant "shining dawn".
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Great human achievements are frequently rewarded with gold, in the
form of gold medals, gold trophies and other decorations. Winners of
athletic events and other graded competitions are usually awarded a
gold medal. 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).
Aristotle in his ethics used gold symbolism when referring to what is
now known as the golden mean. Similarly, gold is associated with
perfect or divine principles, such as in the case of the golden ratio
and the golden rule.
Gold is further associated with the wisdom of aging and fruition. The
fiftieth wedding anniversary is golden. A person's most valued or most
successful latter years are sometimes considered "golden years". The
height of a civilization is referred to as a golden age.
In some forms of
Christianity and Judaism, gold has been associated
both with holiness and evil. In the Book of Exodus, the
Golden Calf is
a symbol of idolatry, while in the Book of Genesis,
Abraham was said
to be rich in gold and silver, and Moses was instructed to cover the
Mercy Seat of the
Ark of the Covenant
Ark of the Covenant with pure gold. In Byzantine
iconography the halos of Christ, Mary and the Christian saints are
According to Christopher Columbus, those who had something of gold
were in possession of something of great value on Earth and a
substance to even help souls to paradise.
Wedding rings have 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 the perfection the marriage signifies. In
Orthodox Christian wedding ceremonies, the wedded couple is adorned
with a golden crown (though some opt for wreaths, instead) during the
ceremony, an amalgamation of symbolic rites.
Main article: List of countries by gold production
Time trend of gold production
World Gold Council states that as of the end of 2017, "there were
187,200 tonnes of stocks in existence above ground". This can be
represented by a cube with an edge length of about 21 meters. At
$1,349 per troy ounce, 187,200 metric tonnes of gold would have a
value of $8.9 trillion.
As of 2017, the world's largest gold producer by far was
455 tonnes. The second-largest producer, Australia, mined 270 tonnes
in the same year, followed by
Russia with 250 tonnes.
Mining and prospecting
Gold mining and
A miner underground at
Pumsaint gold mine, Wales; c. 1938.
Since the 1880s,
South Africa has been the source of a large
proportion of the world's gold supply, and about 50% of the gold
presently accounted is from South Africa. Production in 1970 accounted
for 79% of the world supply, about 1,480 tonnes. In 2007
276 tonnes) overtook
South Africa as the world's largest gold
producer, the first time since 1905 that
South Africa has not been the
As of 2014,
China was the world's leading gold-mining country,
followed in order by Australia, Russia, the United States, Canada, and
Peru. South Africa, which had dominated world gold production for most
of the 20th century, had declined to sixth place. Other major
producers are the Ghana, Burkina Faso, Mali,
Indonesia and Uzbekistan.
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.
Today about one-quarter of the world gold output is estimated to
originate from artisanal or small scale mining.
The city of
Johannesburg located in
South Africa was founded as a
result of the
Gold Rush which resulted in the discovery
of some of the largest natural gold deposits in recorded history. The
gold fields are confined to the northern and north-western edges of
Witwatersrand basin, which is a 5–7 km thick layer of
archean rocks located, in most places, deep under the Free State,
Gauteng and surrounding provinces. These
Witwatersrand rocks are
exposed at the surface on the Witwatersrand, in and around
Johannesburg, but also in isolated patches to the south-east and
south-west of Johannesburg, as well as in an arc around the Vredefort
Dome which lies close to the center of the Witwatersrand
basin. From these surface exposures the basin dips
extensively, requiring some of the mining to occur at depths of nearly
4000 m, making them, especially the Savuka and
TauTona mines to
the south-west of Johannesburg, the deepest mines on earth. The gold
is found only in six areas where archean rivers from the north and
north-west formed extensive pebbly
Braided river deltas before
draining into the "
Witwatersrand sea" where the rest of the
Witwatersrand sediments were deposited.
Second Boer War
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.
During the 19th century, gold rushes occurred whenever large gold
deposits were discovered. The first documented discovery of gold in
United States was at the
Reed Gold Mine
Reed Gold Mine near Georgeville, North
Carolina in 1803. The first major gold strike in the United States
occurred in a small north Georgia town called Dahlonega. Further
gold rushes occurred in California, Colorado, the Black Hills, Otago
in New Zealand, Australia,
Witwatersrand in South Africa, and the
Klondike in Canada.
Extraction and refining
Gold jewelry consumption by country in tonnes
United Arab Emirates
Other Persian Gulf Countries
Gold extraction is most economical in large, easily mined deposits.
Ore grades as little as 0.5 parts per million (ppm) can be
economical. Typical ore grades in open-pit mines are 1–5 ppm;
ore grades in underground or hard rock mines are usually at least
3 ppm. Because ore grades of 30 ppm are usually needed
before gold is visible to the naked eye, in most gold mines the gold
The average gold mining and extraction costs were about $317 per troy
ounce in 2007, but these can vary widely depending on mining type and
ore quality; global mine production amounted to 2,471.1 tonnes.
After initial production, gold is often subsequently refined
industrially by the
Wohlwill process which is based on electrolysis or
by the Miller process, that is chlorination in the melt. The Wohlwill
process results in higher purity, but is more complex and is only
applied in small-scale installations. 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.
The consumption of gold produced in the world is about 50% in jewelry,
40% in investments, and 10% in industry.
According to World
China is the world's largest single
consumer of gold in 2013 and toppled
India for the first time with
Chinese consumption increasing by 32 percent in a year, while that of
India only rose by 13 percent and world consumption rose by 21
India where gold is mainly used for jewelry, China
uses gold for manufacturing and retail.
Mercury cycle and International Cyanide
Gold production is associated with contribution to hazardous
Low-grade gold ore may contain less than one ppm gold metal; such ore
is ground and mixed with sodium cyanide to dissolve the gold. Cyanide
is a highly poisonous chemical, which can kill living creatures when
exposed in minute quantities. Many cyanide spills from gold mines
have occurred in both developed and developing countries which killed
aquatic life in long stretches of affected rivers. Environmentalists
consider these events major environmental disasters. Thirty
tons of used ore is dumped as waste for producing one troy ounce of
Gold ore dumps are the source of many heavy elements such
as cadmium, lead, zinc, copper, arsenic, selenium and mercury. When
sulfide-bearing minerals in these ore dumps are exposed to air and
water, the sulfide transforms into sulfuric acid which in turn
dissolves these heavy metals facilitating their passage into surface
water and ground water. This process is called acid mine drainage.
These gold ore dumps are long term, highly hazardous wastes second
only to nuclear waste dumps.
It was once common to use mercury to recover gold from ore, but today
the use of mercury is largely limited to small-scale individual
miners. Minute quantities of mercury compounds can reach water
bodies, causing heavy metal contamination. Mercury can then enter into
the human food chain in the form of methylmercury. Mercury poisoning
in humans causes incurable brain function damage and severe
Gold extraction is also a highly energy intensive industry, extracting
ore from deep mines and grinding the large quantity of ore for further
chemical extraction requires nearly 25 kW·h of electricity per gram
of gold produced.
Two golden 20 kr coins from the Scandinavian
Monetary Union, which was
based on a gold standard. The coin to the left is Swedish and the
right one is Danish.
Gold has been widely used throughout the world as money, for
efficient indirect exchange (versus barter), and to store wealth in
hoards. For exchange purposes, mints produce standardized gold bullion
coins, bars and other units of fixed weight and purity.
The first known coins containing gold were struck in Lydia, Asia
Minor, around 600 BC. The talent coin of gold in use during the
periods of Grecian history both before and during the time of the life
of Homer weighed between 8.42 and 8.75 grams. From an
earlier preference in using silver, European economies re-established
the minting of gold as coinage during the thirteenth and fourteenth
Bills (that mature into gold coin) and gold certificates (convertible
into gold coin at the issuing bank) added to the circulating stock of
gold standard money in most 19th century industrial economies. In
World War I
World War I the warring nations moved to fractional
gold standards, inflating their currencies to finance the war effort.
Post-war, the victorious countries, most notably Britain, gradually
restored gold-convertibility, but international flows of gold via
bills of exchange remained embargoed; international shipments were
made exclusively for bilateral trades or to pay war reparations.
World War II
World War II gold was replaced by a system of nominally
convertible currencies related by fixed exchange rates following the
Bretton Woods system.
Gold standards and the direct convertibility of
currencies to gold have been abandoned by world governments, led in
1971 by the United States' refusal to redeem its dollars in gold. Fiat
currency now fills most monetary roles.
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
International Monetary Fund in 1999.
Central banks continue to keep a portion of their liquid reserves as
gold in some form, and metals exchanges such as the
Market Association still clear transactions denominated in gold,
including future delivery contracts. Today, gold mining output is
declining. 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 have been replaced by
floating prices for gold and gold future contract. Though the gold
stock grows by only 1 or 2% per year, very little metal is
irretrievably consumed. Inventory above ground would satisfy many
decades of industrial and even artisan uses at current prices.
The gold proportion (fineness) of alloys is measured by karat (k).
Pure gold (commercially termed fine gold) is designated as 24 karat,
abbreviated 24k. English gold coins intended for circulation from 1526
into the 1930s were typically a standard 22k alloy called crown
gold, for hardness (American gold coins for circulation after
1837 contain an alloy of 0.900 fine gold, or 21.6 kt).
Although the prices 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. Gold
has been used as a symbol for purity, value, royalty, and particularly
roles that combine these properties.
Gold as a sign of wealth and
prestige was ridiculed by
Thomas More in his treatise Utopia. On that
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.
ISO 4217 currency code of gold is XAU. Many holders of gold
store it in form of bullion coins or bars as a hedge against inflation
or other economic disruptions. 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
and the British gold sovereign continue to be minted in 22k (0.92)
metal in historical tradition, and the South African Krugerrand, first
released in 1967, is also 22k (0.92).
The special issue
Canadian Gold Maple Leaf
Canadian Gold Maple Leaf coin contains the highest
purity gold of any bullion coin, at 99.999% or 0.99999, while the
Canadian Gold Maple Leaf
Canadian Gold Maple Leaf coin has a purity of 99.99%. In
United States Mint began producing the American Buffalo gold
bullion coin with a purity of 99.99%. The Australian
were first coined in 1986 as the
Australian Gold Nugget
Australian Gold Nugget but changed
the reverse design in 1989. Other modern coins include the Austrian
Vienna Philharmonic bullion coin and the Chinese
Gold as an investment
Gold price history in 1960–2011
As of September 2017, gold is valued at around $42 per gram ($1,300
per troy ounce).
Like other precious metals, gold is measured by troy weight and by
grams. The proportion of gold in the alloy is measured by karat (k),
with 24 karat (24k) being pure gold, and lower karat numbers
proportionally less. 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 nearly pure.
The price of gold is determined through trading in the gold and
derivatives markets, but a procedure known as the
Gold Fixing in
London, originating in September 1919, provides a daily benchmark
price to the 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 receipt redeemable for gold
coin or bullion. 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 ($0.665 per gram),
but in 1934 the dollar was devalued to $35.00 per troy ounce
($0.889/g). By 1961, it was becoming hard to maintain this price, and
a pool of US and European banks agreed to manipulate the market to
prevent further currency devaluation against increased gold
On 17 March 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 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% of the gold known to exist and accounted for today, as
does the similarly laden U.S.
Bullion Depository at Fort Knox. In 2005
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
Sometime around 1970[vague] the price began in trend to greatly
increase, and between 1968 and 2000 the price of gold ranged
widely, from a high of $850 per troy ounce ($27.33/g) on 21 January
1980, to a low of $252.90 per troy ounce ($8.13/g) on 21 June 1999
Gold Fixing). Prices increased rapidly from 2001, but the
1980 high was not exceeded until 3 January 2008 when a new maximum of
$865.35 per troy ounce was set. Another record price was set on
17 March 2008 at $1023.50 per troy ounce ($32.91/g).
In late 2009, gold markets experienced renewed momentum upwards due to
increased demand and a weakening US dollar. On 2
December 2009, gold reached a new high closing at $1,217.23. Gold
further rallied hitting new highs in May 2010 after the European Union
debt crisis prompted further purchase of gold as a safe
asset. On 1 March 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.
From April 2001 to August 2011, spot gold prices more than quintupled
in value against the US dollar, hitting a new all-time high of
$1,913.50 on 23 August 2011, prompting speculation that the long
secular bear market had ended and a bull market had returned.
However, the price then began a slow decline towards $1200 per troy
ounce in late 2014 and 2015.
Moche gold necklace depicting feline heads.
Larco Museum Collection.
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 karat
rating, typically 22k, 18k, 14k or 10k, contain higher percentages of
copper or other base metals or silver or palladium in the alloy.
Nickel is toxic, and its release from nickel white gold is controlled
by legislation in Europe. Palladium-gold alloys are more expensive
than those using nickel. High-karat white gold alloys are 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
By 2014, the gold jewelry industry was escalating despite a dip in
gold prices. Demand in the first quarter of 2014 pushed turnover to
$23.7 billion according to a
World Gold Council report.
Gold solder is used for joining the components of gold jewelry by
high-temperature hard soldering or brazing. If the work is to be of
hallmarking quality, the gold solder alloy must match the fineness
(purity) of the work, and alloy formulas are manufactured 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.
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.
also be made into thread and used in embroidery.
Only 10% of the world consumption of new gold produced goes to
industry, but by far the most important industrial use for new gold
is in fabrication of corrosion-free electrical connectors in computers
and other electrical devices. For example, according to the World Gold
Council, a typical cell phone may contain 50 mg of gold, worth
about 50 cents. But since nearly one billion cell phones are produced
each year, a gold value of 50 cents in each phone adds to $500 million
in gold from just this application.
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
coating on electrical connectors, thereby ensuring good connection.
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 has been debated; gold connectors are often criticized by
audio-visual experts as unnecessary for most consumers and seen as
simply a marketing ploy. 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.
Besides sliding electrical contacts, gold is also used in electrical
contacts because of its resistance to corrosion, electrical
conductivity, ductility and lack of toxicity. 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.
The concentration of free electrons in gold metal is
Gold is highly conductive to electricity,
and has been used for electrical 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.
It is estimated that 16% of the world's gold and 22% of the world's
silver is contained in electronic technology in Japan.
Metallic and gold compounds have long been used for medicinal
purposes. Gold, usually as the metal, is perhaps the most anciently
administered medicine (apparently by shamanic practitioners) and
known to Dioscorides. 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
In the 19th century gold had a reputation as a "nervine", a therapy
for nervous disorders. Depression, epilepsy, migraine, and glandular
problems such as amenorrhea and impotence were treated, and most
notably alcoholism (Keeley, 1897).
The apparent paradox of the actual toxicology of the substance
suggests the possibility of serious gaps in the understanding of the
action of gold in physiology. Only salts and radioisotopes of
gold are of pharmacological value, since elemental (metallic) gold is
inert to all chemicals it encounters inside the body (i.e., ingested
gold cannot be attacked by stomach acid). Some gold salts do have
anti-inflammatory properties and at present two are still used as
pharmaceuticals in the treatment of arthritis and other similar
conditions in the US (sodium aurothiomalate and auranofin). These
drugs have been explored as a means to help to reduce the pain and
swelling of rheumatoid arthritis, and also (historically) against
tuberculosis and some parasites.
Gold alloys are used in restorative dentistry, especially in tooth
restorations, such as crowns and permanent bridges. 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.
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 and
materials science. The technique of immunogold labeling exploits the
ability of the gold particles to adsorb protein molecules onto their
Colloidal gold particles coated with specific antibodies can
be used as probes for the presence and position of antigens on the
surfaces of cells. In ultrathin sections of tissues viewed by
electron microscopy, the immunogold labels appear as extremely dense
round spots at the position of the antigen.
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. 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 the spatial
resolution of the image.
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.
The isotope gold-198 (half-life 2.7 days) is used, in nuclear
medicine, in some cancer treatments and for treating other
Gold can be used in food and has the
E number 175. In 2016, the
European Food Safety Authority
European Food Safety Authority published an opinion on the
re-evaluation of gold as a food additive. Concerns included the
possible presence of minute amounts of gold nanoparticles in the food
additive, and that gold nanoparticles have been shown to be genotoxic
in mammalian cells in vitro.
Gold leaf, flake or dust is used on and in some gourmet foods, notably
sweets and drinks as decorative ingredient.
Gold flake was used
by the nobility in medieval 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.[citation
Gold water of Danzig) or Goldwasser
(English: Goldwater) is a traditional German herbal liqueur
produced in what is today Gdańsk, Poland, and Schwabach, Germany, and
contains flakes of gold leaf. There are also some expensive (c. $1000)
cocktails which contain flakes of gold leaf. However, since
metallic gold is inert to all body chemistry, it has no taste, it
provides no nutrition, and it leaves the body unaltered.
Vark is a foil composed of a pure metal that is sometimes gold,
and is used for garnishing sweets in South Asian cuisine.
Mirror for the
James Webb Space Telescope
James Webb Space Telescope coated in gold to reflect
Gold produces a deep, intense red color when used as a coloring agent
in cranberry glass.
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.
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 such as the EA-6B Prowler.
Gold is used as the reflective layer on some high-end CDs.
Automobiles may use gold for heat shielding.
McLaren uses gold foil in
the engine compartment of its F1 model.
Gold can be manufactured so thin that it appears semi-transparent. It
is used in some aircraft cockpit windows for de-icing or anti-icing by
passing electricity through it. The heat produced by the resistance of
the gold is enough to prevent ice from forming.
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
Gold cyanide is the electrolyte used in commercial
electroplating 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.
Gold chloride and
gold oxide are used to make cranberry or red-colored glass, which,
like colloidal gold suspensions, contains evenly sized spherical gold
Pure metallic (elemental) gold is non-toxic and non-irritating when
ingested and is sometimes used as a food decoration in the form
of gold leaf. Metallic gold is also a component of the alcoholic
Gold Strike, and Goldwasser. Metallic gold is
approved as a food additive in the EU (E175 in the Codex
Alimentarius). Although the 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.
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.
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. Despite this, gold is a relatively non-potent contact
allergen, in comparison with metals like nickel.
A sample of the fungus
Aspergillus niger was found growing from gold
mining solution; and was found to contain cyano metal complexes; such
as gold, silver, copper iron and zinc. The fungus also plays a role in
the solubilization of heavy metal sulfides.
Bulk leach extractable gold
Chrysiasis (dermatological condition)
Commodity fetishism (Marxist economic theory)
Digital gold currency
Gold Anti-Trust Action Committee
Gold phosphine complex
Gold Prospectors Association of America
List of countries by gold production
Mining in Roman Britain
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