Gold: the legend lives on
Did you know?
The word Carat is taken from the carob seeds that people used in
ancient times to balance scales. Do not confuse the terms Carat and
CARAT: A measurement of weight. One metric carat is equivalent to 0.2
grams (or 200 milligrams).
KARAT: A measurement of gold purity.
Have you heard of Tutankhamen’s funerary mask? It became famous because
it was made of gold. Gold 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. Egypt and Nubia had the
resources to make them major gold-producing areas for much of history.
Gold is a chemical element with the symbol Au (from the Latin ‘aurum’)
and atomic number 79. It is a highly sought-after precious metal which,
for many centuries, has been used as money, a store of value and in
jewelry. Gold forms the basis for a monetary standard used by the
International Monetary Fund (IMF) and the Bank for International
Settlements (BIS). In various countries, gold is used as a standard for
monetary exchange, in coinage and in jewelry.
Pure gold is too soft for ordinary use and is typically hardened by
alloying with copper or other base metals. The gold content of gold
alloys is measured in carats (k), pure gold being designated as 24k.
Today, gold has fallen out of use in coins made for general circulation.
Modern industrial uses include dentistry and electronics, where gold has
traditionally found use because of its good resistance to oxidative
corrosion. Gold does not react with most chemicals, but is attacked by
chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury,
forming amalgam alloys, but does not react with it. Gold is insoluble in
nitric acid, which will dissolve silver and base metals. Thus nitric
acid has long been used to confirm the presence of gold in items, and
this is the origin of the colloquial term “acid test,” referring to a
gold standard test for genuine value. Gold is also a good conductor of
heat and electricity.
Many competitions, and honours, such as the Olympics and the Nobel
Prize, award a gold medal to the winner.
Gold occurs as nuggets or grains in rocks, underground “veins” and in
alluvial deposits. It is dense, soft, shiny and the most malleable and
ductile of the known metals. Pure gold has an attractive bright yellow
Is it toxic?
Generally, gold is non-toxic if consumed, and is used as food
decoration in the form of gold leaf. However, consumption and thereby
accumulation in the body of a large amount of gold (or gold compounds)
is still toxic and the symptoms are similar to those of heavy metal
Different colours of gold!
Because of the softness of pure (24k) gold, it is usually alloyed with
base metals for use in jewellery, altering its hardness and ductility,
melting point, colour and other properties. Alloys with lower “k”,
typically 22k, 18k, 14k or 10k, contain higher percentages of copper,
silver or other base metals in the alloy. Copper is the most commonly
used base metal, yielding a redder metal. Fourteen carat gold-copper
alloy is nearly identical in colour to certain bronze alloys, and both
may be used to produce police and other badges.
Blue gold can be made by alloying with iron, and purple gold can be made
by alloying with aluminum, although rarely done except in special
jewelry. Fourteen and eighteen carat gold alloys with silver alone
appear greenish-yellow and are referred to as green gold.
Alternative white gold alloys are available, based on palladium, silver
and other white metals.
Why is it so expensive?
The high price of gold is due to its rarity. Only three parts out of
every billion (0.000000003) in the Earth’s crust is gold. But 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 on a side. 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 karats 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 being
Gold is a rare yellow metal with the designated symbol
AU, which is short for the Latin word ‘Aurum’ and which means literally,
“Glowing Dawn”. The word gold, however, comes from the Indo-European
root word and means simply, yellow.