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News, Articles and Information
GOLD
Gold, as an element, is a dense, shiny, deep yellow precious metal. It has
several qualities that have made it valuable throughout history, both as a
medium of exchange and for decorative use as jewelry. It is attractive in color
and brightness; it is so durable it's practically indestructible. Gold is also
rare and usually found in nature in a relatively pure form. Gold is the most
malleable and ductile of metals. It may be beaten into gold leaf as thin as 4
millionths of an inch - an ounce can be beaten out to 187 square feet. An ounce
of gold can also be drawn into a wire more than 40 miles long. Gold is a good
conductor of electricity, though not as good as silver or copper. Gold is the
noblest of the "noble metals" – (gold, platinum, palladium and rhodium) so
called because of their inertness, or reluctance to enter into chemical
reactions. Gold will not combine directly with oxygen nor will it react with
common acids. It is, however, attacked by a 3-to-1 mixture of hydrochloric and
nitric acids. This reagent is called aqua regia (Latin for royal water) because
it reacts with the so-called royal metal. Gold is commonly alloyed with other
metals, as in jewelry, in proportions that yield desired harnesses and colors.
An alloy of gold, silver, and copper, in which the amounts of silver
predominates, is called "green gold." An alloy of the same three elements in
which copper predominates is called "red gold." An alloy of gold and nickel is
called "white gold." The purity of gold is expressed in karats (kt), on a scale
of 24, or in fineness, on a scale of 1,000. Pure gold is 24 karat, or 1,000
fine. An alloy containing 75 percent gold would be described as 18-karat gold
or 750 fine. Because gold is visually pleasing, workable and does not tarnish
or corrode, it was one of the first metals to attract human attention. Examples
of elaborate gold workmanship, many in nearly perfect condition, survive from
ancient Egyptian, Minoan, Assyrian, and Etruscan artisans, and gold has
continued to be a highly favored material out of which to craft jewelry and
other decorative objects. The search for gold has been a major force in
history. Men have fought wars and conquered empires to obtain it. Desire for
gold motivated the conquests of Alexander the Great and the campaigns of Julius
Caesar. The hope of finding gold also inspired the voyages of Christopher
Columbus, Vasco da Gama, Ferdinand Magellan, and other explorers. In the Middle
Ages, alchemists sought to make gold from the base metals lead and copper. The
alchemists failed, but the modern science of chemistry gradually evolved from
their work. Because of it’s to its unique qualities, gold has been universally
accepted in exchange for goods and services. Gold began to serve as backing for
paper-currency systems when they became widespread in the 19th century, and
although gold's official role in the international monetary system had come to
an end by the 1970s, gold remains a highly regarded reserve asset. In the last
500 years, about 80,000 tons of gold have been taken from the earth. World
reserves of gold economically recoverable by present methods may total only
about 32,000 tons. Since gold is both durable and carefully guarded, most of
the gold that has been taken from the earth still exists. Much of it has been
buried again -- in underground vaults, where it is held in government monetary
reserves. Approximately 45% of the entire world's gold is held by governments
and central banks for this purpose. Gold is still accepted by all nations as a
medium of international payment. Gold is widely distributed throughout the
world. Tiny quantities occur in most rocks and soils. Its abundance in the
Earth's crust is estimated at about 0.005 parts per million. Usually, however,
the amount of gold is so minute that the cost of extracting it would exceed its
value. Gold is despersed in low concentrations in all igneous rocks. It occurs
mostly in the native state, remaining chemically uncombined. It often occurs in
association with copper and lead deposits, and, though the quantity present is
often extremely small, it is readily recovered as a by-product in the refining
of those base metals. One-third of all gold is produced as a by-product of
copper, lead, and zinc production. Where gold occurs in higher concentrations,
the deposits are of two basic types: hydrothermal veins, associated with quartz
and pyrite (fool's gold); and placer deposits that are derived from the erosion
of gold-bearing rocks and appear in alluvium and stream beds.
News, Articles and Information The origin of
enriched veins is not known but theories contend that gold was carried to the
surface from great depths in the earth's mantle, in partial solid solution, and
later solidified. In addition to its historic use as currency and jewelry, gold
has also been applied in dentistry and medicine. Today, because of its
non-corrosive properties it is playing an increasing role in industrial
processes. In the late 20th century four countries, South Africa, Russia, the
United States, and Australia accounted for two-thirds of the gold produced
annually throughout the world. South Africa alone, with its vast Witwatersrand
mines, produces about one-third of the world's gold. Physical Properties of
Gold.
Melting point: 1063 degrees K
Symbol: Au
Crystal System: Face-centered cubic
crystal Hardness: 2.5 – 3.0 Mohs'
Cleavage: None
Fracture: None
Specific Gravity: 19.3
Color: deep yellow
Luster: bright, shiny, metallic
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