2. MEANINGMEANING
Gold is a chemical element with the symbol AuGold is a chemical element with the symbol Au
and atomic number 79. It is a dense, soft,and atomic number 79. It is a dense, soft,
malleable, and ductile metal with a bright yellowmalleable, and ductile metal with a bright yellow
color and luster that is considered attractive,color and luster that is considered attractive,
which is maintained without tarnishing in air orwhich is maintained without tarnishing in air or
water. water.
4. Color of GoldColor of Gold
Whereas most other pure metals are gray or silveryWhereas most other pure metals are gray or silvery
white, gold is yellow. This color is determined by thewhite, gold is yellow. This color is determined by the
density of loosely bound (valence) electrons; thosedensity of loosely bound (valence) electrons; those
electrons oscillate as a collective "plasma" mediumelectrons oscillate as a collective "plasma" medium
described in terms of a described in terms of a quasiparticlequasiparticle called called plasmonplasmon..
The frequency of these oscillations lies in theThe frequency of these oscillations lies in the
ultraviolet range for most metals, but it falls into theultraviolet range for most metals, but it falls into the
visible range for gold due to subtle visible range for gold due to subtle relativistic effectsrelativistic effects
that affect the that affect the orbitalsorbitals around gold atoms. around gold atoms.[24][24][25][25]
Similar effects impart a golden hue to metallic Similar effects impart a golden hue to metallic
caesiumcaesium..
Common Common colored goldcolored gold alloys such as rose gold can alloys such as rose gold can
be created by the addition of various amounts ofbe created by the addition of various amounts of
copper and silver, as indicated in the triangularcopper and silver, as indicated in the triangular
diagram to the left. Alloys containing palladium ordiagram to the left. Alloys containing palladium or
nickel are also important in commercial jewelry asnickel are also important in commercial jewelry as
these produce white gold alloys. Less commonly,these produce white gold alloys. Less commonly,
addition of addition of manganesemanganese, , aluminiumaluminium, , ironiron, , indiumindium
and other elements can produce more unusual and other elements can produce more unusual
colors of gold for various applications.colors of gold for various applications.
5. Isotopes of goldIsotopes of gold
Gold has only one stable Gold has only one stable isotopeisotope, 197Au, which, 197Au, which
is also its only naturally occurring isotope.is also its only naturally occurring isotope.
Thirty-six Thirty-six radioisotopesradioisotopes have been synthesized have been synthesized
ranging in ranging in atomic massatomic mass from 169 to 205. The from 169 to 205. The
most stable of these is 195Au with a most stable of these is 195Au with a half-lifehalf-life of of
186.1 days.186.1 days.
6. Applications of GoldApplications of Gold
Monetary exchangeMonetary exchange
InvestmentInvestment
JewelryJewelry
MedicineMedicine
Food and drinkFood and drink
IndustryIndustry
ElectronicsElectronics
Commercial chemistryCommercial chemistry
7. Monetary exchangeMonetary exchange
Gold has been widely used throughout the world as a Gold has been widely used throughout the world as a
vehiclevehicle for for monetarymonetary exchange, either by issuance and exchange, either by issuance and
recognition of recognition of gold coinsgold coins or other bare metal quantities, or or other bare metal quantities, or
through gold-convertible paper instruments bythrough gold-convertible paper instruments by
establishing establishing gold standardsgold standards in which the total value of in which the total value of
issued money is represented in a store of gold reserves.issued money is represented in a store of gold reserves.
8. InvestmentInvestment
Many holders of gold store it in form of Many holders of gold store it in form of bullionbullion
coins or coins or barsbars as a hedge against as a hedge against inflationinflation or or
other economic disruptions. other economic disruptions.
The The ISO 4217ISO 4217 currency code of gold is XAU. currency code of gold is XAU.
Modern Modern bullion coinsbullion coins for investment or for investment or
collector purposes do not require goodcollector purposes do not require good
mechanical wear properties; they are typicallymechanical wear properties; they are typically
fine gold at 24k,fine gold at 24k,
South African South African KrugerandKrugerand, first released in 1967,, first released in 1967,
9. JewelryJewelry
Because of the softnessBecause of the softness
of pure (24k) gold, it isof pure (24k) gold, it is
usually usually alloyedalloyed with with
base metals for use inbase metals for use in
jewelry, altering itsjewelry, altering its
hardness and ductility,hardness and ductility,
melting point, color andmelting point, color and
other properties. Alloysother properties. Alloys
with lower caratage,with lower caratage,
typically 22k, 18k, 14ktypically 22k, 18k, 14k
or 10k, contain higheror 10k, contain higher
percentages of copperpercentages of copper
or other base metals oror other base metals or
silver or palladium insilver or palladium in
the alloy. the alloy. CopperCopper is the is the
most commonly usedmost commonly used
base metal, yielding abase metal, yielding a
redder color.redder color.[37][37]
10. MedicineMedicine
Conceived of as perhaps the most
anciently administered medicine
(apparently according to one
source by shamanic practitioners
Even some modernesotericists
and forms of
alternative medicine assign
metallic gold a healing power.
Some gold salts do have
anti-inflammatory properties and
are used as pharmaceuticals in
the treatment of arthritis and
other similar conditions.
11. Food and drinkFood and drink
Gold can be used in food and has the Gold can be used in food and has the E numberE number
175. 175.
Gold leafGold leaf, flake or dust is used on and in some, flake or dust is used on and in some
gourmet foods, notably sweets and drinks asgourmet foods, notably sweets and drinks as
decorative ingredient. Gold flake was used by thedecorative ingredient. Gold flake was used by the
nobility in nobility in medieval Europemedieval Europe as a decoration in food as a decoration in food
and drinks, in the form of leaf, flakes or dust, eitherand drinks, in the form of leaf, flakes or dust, either
to demonstrate the host's wealth or in the beliefto demonstrate the host's wealth or in the belief
that something that valuable and rare must bethat something that valuable and rare must be
beneficial for one's health.beneficial for one's health.
Most of the gold leaf used for sweet and facialMost of the gold leaf used for sweet and facial
products.products.
12. IndustryIndustry
Gold Gold soldersolder is used for joining the components of gold is used for joining the components of gold
jewelry by high-temperature hard soldering or jewelry by high-temperature hard soldering or brazingbrazing
Gold can be made into Gold can be made into threadthread and used in and used in embroideryembroidery..
Gold produces a deep, intense red color when used asGold produces a deep, intense red color when used as
a coloring agent in a coloring agent in cranberry glasscranberry glass..
Gold is a good reflector of Gold is a good reflector of electromagnetic radiationelectromagnetic radiation
such as such as infraredinfrared and and visible lightvisible light as well as as well as
radio wavesradio waves..
McLarenMcLaren uses gold foil in the engine compartment of uses gold foil in the engine compartment of
its its F1F1 model . model .
13. ElectronicsElectronics
Gold is highly Gold is highly conductiveconductive to electricity, and to electricity, and
has been used for has been used for electrical wiringelectrical wiring in some in some
high-energy applications high-energy applications
For example, gold electrical wires were usedFor example, gold electrical wires were used
during some of the during some of the Manhattan ProjectManhattan Project's's
atomic experimentsatomic experiments
14. Commercial chemistryCommercial chemistry
Gold is attacked by and dissolves in alkalineGold is attacked by and dissolves in alkaline
solutions of potassium or sodium solutions of potassium or sodium cyanidecyanide, to, to
form the salt gold cyanide—a technique thatform the salt gold cyanide—a technique that
has been used in extracting metallic goldhas been used in extracting metallic gold
from ores in the from ores in the cyanide processcyanide process. Gold. Gold
cyanide is the cyanide is the electrolyteelectrolyte used in used in
commercial commercial electroplatingelectroplating of gold onto base of gold onto base
metals and metals and electroformingelectroforming..
15. Cultural historyCultural history
Egyptian hieroglyphsEgyptian hieroglyphs from as early as 2600 BC from as early as 2600 BC
describe gold,describe gold,
Gold artifacts found at the Gold artifacts found at the Nahal KanaNahal Kana cave cave
cemetery dated during the 1980s, cemetery dated during the 1980s,
new methods for extracting gold on a large scalenew methods for extracting gold on a large scale
were developed by introducing were developed by introducing hydraulic mininghydraulic mining
methods, methods,
especially inespecially inHispaniaHispania from 25 BC onwards and in from 25 BC onwards and in
DaciaDacia from 106 AD onwards. One of their largest from 106 AD onwards. One of their largest
mines was at mines was at Las MedulasLas Medulas in in León (Spain)León (Spain),,
16. Gold miningGold mining in worldin world
The city of The city of JohannesburgJohannesburg
located in located in South AfricaSouth Africa was was
founded as a result of the founded as a result of the
Witwatersrand Gold RushWitwatersrand Gold Rush which which
resulted in the discovery of someresulted in the discovery of some
of the largest gold deposits theof the largest gold deposits the
world has ever seenworld has ever seen
Other major producers are theOther major producers are the
United States, Australia, Russia,United States, Australia, Russia,
and and PeruPeru, as well as, , as well as, GhanaGhana, ,
Burkina FasoBurkina Faso, , MaliMali, Indonesia, Indonesia
and Uzbekistan. Mines in and Uzbekistan. Mines in
South DakotaSouth Dakota and and NevadaNevada
supply two-thirds of gold used supply two-thirds of gold used
in the United States. In Southin the United States. In South
America,America,
18. ConsumptionConsumption
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, purchasing
approximately 800 tonnes
of gold every year, mostly
for jewelry. India is also
the largest importer of
gold; in 2008, India
imported around 400
tonnes of gold. Indian
households hold 18,000
tonnes of gold which
represents 11% of the
19. PricePrice
Like other precious metals, gold is measured by troy weight andLike other precious metals, gold is measured by troy weight and
by grams. When it is alloyed with other metals theby grams. When it is alloyed with other metals the
termtermcaratcarat or or karatkarat is used to indicate the purity of gold present, is used to indicate the purity of gold present,
The price of gold is determined through trading in the goldThe price of gold is determined through trading in the gold
and derivatives markets,and derivatives markets,
the price of gold was left to find its free-market level. Centralthe price of gold was left to find its free-market level. Central
banks still hold historical gold reserves as a store ofbanks still hold historical gold reserves as a store of
value although the level has generally been declining. value although the level has generally been declining.