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Gold
Item # BUG
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Gold is a chemical
element in the periodic table that has the symbol
Au (from the Latin aurum) and atomic
number79. 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 or grains in rocks and in alluvial deposits
and is one of the coinage metals.
For millennia, gold has served as money and is also
used in jewelry,
dentistry, and in electronics. Gold forms the basis
for a monetary standard used by the International
Monetary Fund (IMF) and the Bank for International
Settlements (BIS). Its ISO currency code is XAU.]
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 |
General |
| Name, Symbol, Number |
gold, Au, 79 |
| Chemical series |
transition metals |
| Group, Period, Block |
11, 6, d |
| Appearance |
Metallic yellow |
| Atomic mass |
196.966569(4) g/mol |
| Electron configuration |
[Xe] 4f14 5d10 6s1 |
| Electrons per shell |
2, 8, 18, 32, 18, 1 |
Physical
properties |
| Phase |
Solid |
| Density (near r.t.) |
19.3 g/cm³ |
| Liquid density t m.p. |
17.31 g/cm³ |
| Melting point |
1337.33 K
(1064.18 °C, 1947.52 °F) |
| Boiling point |
3129 K
(2856 °C, 5173 °F) |
| Heat of fusion |
12.55 kJ/mol |
| Heat of vaporization |
324 kJ/mol |
| Heat capacity |
(25 °C) 25.418 J/(mol•K) |
P/Pa |
1 |
10 |
100 |
1
k |
10
k |
100
k |
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Notable
characteristics
Item # 5513 |
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.
Only silver colloids
exhibit the same interactions with light, albeit at a
shorter frequency, making silver colloids yellow in color.
It is the most malleable and ductile metal known; a single
gram can be beaten into a sheet of one square metre, 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 Statesto
the tourist trade as “ Black Hills” gold.
Adding copper yields a redder metal, iron blue, Silver
produces green, aluminium purple, platinum
metals white, and natural bismuth together with silver
alloys produce black. Native gold contains usually eight
to ten per cent silver,
but often much more — alloys
with a silver content over 20% are called electrum. As
the amount of silver increases, the color becomes whiter
and the specific gravity reduces.
Gold is a good conductor of heat and electricity, and
is not affected by air and most reagents. Heat, moisture,
oxugen, and most corrosive agents have very little chemical
effect on gold, making it well-suited for use in coins
and jewelry; conversely, halogens will chemically alter
gold, and aqua regia dissolves it.
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 presipiated
out as gold metal by the addition of virtually any other
metal as the reducing agent. The added metal is oxidazed
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
Item # 6333 |
Pure gold
is too soft for ordinary use and is hardened by alloying
with silver, copper, and other metals. Gold and its many
alloys are most often used in jewelry,
coinage and as a standard for monetary exchange in many
countries. Because of its high electrical conductivity
and resistance to corrosion and other desirable combinations
of physical and chemical properties, gold also emerged
in the late 20 th century as an essential industrial metal.
• Gold can be made into thread and used in embroidery.
• Gold performs critical functions in components,
communications equipment, spacecraft, jet aircraft engines,
and a host of other products.
• The resistance to oxidation of gold has led to
its widespread use as thin layers electroplated on the
surface of electrical connectors to ensure a good connection.
• Gold is used in restorative dentistry especially
in tooth restorations such as crowns and bridges.
• Colloidal gold (a gold nanopracticale) is an intensely
colored solution that is currently studied in many labs
for medical, biological and other applications. It is
also the form used as gold paint on ceramics prior to
firing.
• Chlorauric acid is used in photography for toning
the silver image.
• Gold (III) chlorideis used as a catalist in orgaic
chemistry. It is also the usual starting point for making
other gold compounds.
• Gold is used as a coating enabling biological
material to be viewed under a scanning electron microscope.
• Many competitions and honors, such as the Olimpics
and the Nobel Prize, award a gold medal to the winner
(with silver to the second-place
finisher, and bronze to the third.)
• Since it is a good reflector of both infrared
and visible light, it is used for the protective coatings
on many artificial satellites and on the helmet of astronauts
helmets to prevent blindness from the sun.
• Disodium aurothiomalate is a treatment for rheumatoid
artritis (administered intramuscularly). It inhibits limphocyte
proliferation,lysosomal enzyme release, the release of
reactive oxyden 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 flake is used on and in some gourmet sweets
and drinks. Called varak or (varaq) in India. Having no
reactivity it adds no taste but is taken as a delicacy.
Some use it as an excuse to create super-expensive delicacies
($1,000 cocktails). For similar reasons, it also used
as the basis for some superstitious, over the top, health
claims. Only the salts and radioisotopes (mentioned above)
have any evidence of medicinal value.
• White gold
(an alloy of gold with platimum,
palladium,nickel, and/or zinc) serves as a substitute
for platinum.
Because 18k white gold is 75% gold, and 14k white gold
is 58.3% gold, jewelry made from these metals has a slight
yellow color. To enhance the whiteness, almost all white
gold is plated with rhodium, a shiny, white metal which
is extremely hard. Depending on the amount of wear to
a piece of jewelry, over time this rhodium plating may
wear off, revealing the original metal color. Re-plating
is a simple process that can be done to restore your jewelry's
whiteness if needed
• 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).
Rose gold gets its color from a larger proportion
of copper in the metal alloy. This gives the gold a beautiful
pink color.
The color of gold is determined by two factors:
• The type of metal alloys included in it
• The percentage of each metal alloy
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History
Item # 7175
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| Discovered by:
Known since ancient times. |
| Discovered at : not known |
| Discovered when: no data |
Gold (Sanskrit jval,Greek
χρυσóς [khrisós],Latin
aurum for "shining dawn", Anglo-Saxon
gold, Chinese 金 [jīn], Japanese
金 [kin] ) has been
known and highly valued since prehistoric times. It
may have been the first metal used by humans and was valued for ornamentation and
rituals. Egyptian hieroglyphs from as early as2600 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
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.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,
Pery, and Colombia.
Gold has long been considered
one of the most precious
matals, and its value has been used as the standard
for manycurrencies (known as the gold standart) 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 1920. 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 alchemistc 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 thecircle with a point at its center (?), which
was also theastrological symbol, the Egyptian hieroglyph
and the ancient Chinese character for the Sun (now ?).During
the 19th century, gold rushes occurred whenever large
gold deposits were discovered, including the California,
Colorado, Otago, Australia, Witwatersrand Black Hills,
and Klondake gold rushes.
Because of its historically high value, much of the
gold mined throughout history is still in circulation
in one form or another. |
Occurrence
Item
# 6886
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Due to
its relative chemical inertness gold is usually found
as the native metal or alloy. Occasionally large accumulations
of native gold (also known asnuggest) occur but usually
gold occurs as minute grains. These grains occur between
mineral grain boundaries or as inclusions within minerals.
Common gold associations are quartz often asveins and
sulfide minerals. The most common sulfide associations
are purity,chalcopyrity, galena,sphalerite,arsenopyrity,
stibnite and pyrrhotite. Rarer mineral associations
are petzite,calaverite, sylvanite, muthmannite,nagyagite
andkrennerite.
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 igneouse rocks; alluvial deposits and placer
deposits originate from these sources.
The primary source of gold is usually igneous rocks
or surface concentrations. A deposit usually needs some
form of secondary enrichment to form an economically
viable ore deposit: either chemical or physical processes
like erosion or solution or more generallymetamorphizm,
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.
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Production
Item # 704 |
Economic
gold extraction can be achieved from ore grades as little
as 0.5 g/1000 kg (0.5 ppm) on average in large easily
mined deposits, typical ore grades in open-pit mines are
1–5 g/1000 kg (1-5 ppm), ore grades in underground
or hard rock mines are usually at least 3 g/1000 kg (3
ppm) on average. Ore grades of 30 g/1000 kg (30 ppm) are
usually needed before gold 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 throughout
the history of mankind could be incorporated in a solid
ball with a diameter of 27metres.
Since the 1880s South Africa has been the source for a
large proportion of the world's gold supply. Production
in 1970 accounted for 79% of the world supply, producing
about 1,000 tonnes, however production in 2004 was 342
tonnes. This decline was due to the increasing difficulty
of extraction and changing economic factors affecting
the industry in South Africa.
The city of Johannesburg was built atop the world's greatest
gold finds. Gold fields in the Orange Free State and the
Transvaal are deep and require the world's deepest mines.
The Second Boer War of 1899-1901 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 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 b Rascua
Lama aims at exploitation of rich fields in the high mountains
of Atacama, at the border between Chile and Argentina.
After initial production, gold is often subsequently refined
industrially by the Wohlwill process or the Miller process.
Other methods of assaying and purifying smaller amounts
of gold includeparting and inquartation as well as cuppelation,
or refining methods based on the dissolution of gold in
aqua regia.
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 thephilosopher’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 transformation in
partical accelerators The gold isotopes produced would
likely be radioctive. No economically feasible method
to manufacture gold artificially has been found and published
yet. The possibility of cheap man-made gold would have
unforeseen economic and political consequences.
The world's oceans hold a vast amount of gold, but in
very low concentrations (perhaps 1-2 parts per billion).
Fritz Haber (the German inventor of the Haber process)
attempted commercial extraction of gold from sea water
in an effort to help pay Germany's reparations following
the First World War. Unfortunately, his assessment of
the concentration of gold in sea water was unduly high,
probably due to sample contamination. The effort produced
little gold and cost the German government far more than
the commercial value of the gold recovered. No commercially
viable mechanism for performing gold extraction from sea
water has yet been identified.
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Price
Item # 7030
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Like
other precious
metals, gold is measured bytroy weight and bygrams.
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 themillesimal 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
industry.
Historically gold was used to back currency in an economic
system known as the gold standart 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 in1934 the price
of gold was set at $35.00 per troy ounce ($1125.27/kg).
By 1961 it was becoming hard to maintain this price, and
a pool of US and European banks began to act together
to defend the price against market forces.
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 historicalgold 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.
Since 1968 the price of gold on the open market has ranged
widely, with a record high of $850/oz ($27,300/kg) on21
january 1980, to a low of $252.90/oz ($8,131/kg) on 21
June1999 (London Fixing). Prices have risen to the $570/oz
($18,300/kg) mark in early 2006. |
For more information
Item # 6257L
|
The
gold standard defines the world's currency system, whereby
money represents a value in gold.
24 karat = 100% gold
Too soft for jewelry
22 karat = 91.7% gold
Very soft ˜ not recommended for jewelry
18 karat = 75.0% gold
Recommended for fine jewelry
14 karat
= 58.3% gold
Recommended for jewelry
12 karat = 50.0% gold
Not acceptable for jewelry
10 karat = 41.7% gold
The legal karat limit considered
as real gold in the United States .
Karatage, noted by a number followed
by "k" indicates purity, or how much of the
metal in a piece of jewelry is gold.
Much of Cubic Zirconia CZ Platinum Jewelry is made of the most beautiful and durable
14k gold.
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14
Karat Gold Facts |
GOLD
KARAT AND ALLOY COMPOSITION |
KARAT
GOLD ** |
**
FINE GOLD ** |
**
ALLOY METALS |
0K |
.0000 |
1.0000 |
1K |
.0417 |
9.583 |
6K |
.2500 |
.7500 |
8K |
.3333 |
.6667 |
9K |
.3750 |
.6250 |
10K |
.4167 |
.5833 |
12K |
.5000 |
.5000 |
14K |
.5833 |
.4167 |
18K |
.7500 |
.2500 |
22K |
.9167 |
.0833 |
24K |
1.0000 |
.0000 |
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Restrictions
on gold ownership |
Item # 2565 |
| Because
of its use as a reserve store of value, the possession
of gold is sometimes restricted or banned. Within the
United States, the private possession of gold except as
jewelry
and coin collecting was banned between 1933 and 1975.
President Franklin D. Roosevelt expropriated 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. |
Precautions
|
Item # Pd9 |
| 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.
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Symbolism |
Item # 5833 |
Gold
has been associated with the extremities of utmost evil
and great sanctity throughout history. The Golden Calf
is a widely-recognised symbol of idolary and revolt against
God. 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 Olimpic 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 Christ Cristian 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.
CARE
Keep your gold jewelry away from
harsh chemicals such as chlorine and cleaning fluids.
This will reduce daily abrasions and prolong gold's
luster. To clean gold jewelry, use a solution of warm
water and detergent-free soap and wash gold gently with
a soft-bristled brush (a dull tooth brush works well).
Store gold pieces separately in soft cloth bags or original
boxes to protect them from the exposure to harsh daily
elements.
View our beautiful Cubic
Zirconia CZ Platinum gold jewelry
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