One of the most unreactive metals in the periodic table of elements. Alchemists used to call gold one of the "noble" metals because of its resistance to oxidation under most normal circumstances. Its chemical symbol is Au, short for Aurum, which is Latin for gold.
Gold has many varied uses which range from ornaments to jewellery to electronics to spacecraft to medicine.
Physical characteristics
Gold is relatively soft -- pure gold is indentable by the pressure of human teeth.
It is also the most malleable and ductile of all metals -- one ounce of pure gold can be pounded into a thin sheet of metal measuring 300 square feet and can be drawn into a thin wire 5 miles long.
Gold is the most reflective and least absorptive material of infrared (heat) energy -- high purity gold reflects up to 99% of infrared rays. Gold is also an excellent conductor of thermal energy or heat -- a 35% gold alloy is used in the main engine nozzle of the Space Shuttle, where temperatures can reach 3300° centigrade.
The specific gravity or density of pure gold is 19.3 compared to 14.0 for mercury and 11.4 for lead.
Gold mining
Gold is scarce and occurs naturally as impure gold, with a density of between 16 to 18. The rock that gold is commonly found in has a density of about 2 to 3. The difference in density enables gold to be separated from clay, silt, sand, and gravel by agitating with devices such as the gold pan (panning for gold), rocker, and sluicebox.
Gold is often recovered from ore by reacting with mercury which forms an amalgam with gold. Gold is extracted from the amalgam by heating the amalgam to remove the mercury. Cyanide is sometimes used for extracting gold from low grade ores.
Karats and purity
Not to be confused with carats (a measure of the weight of precious stones), a Karat (K) is a measure of the fineness or purity of gold expressed as a fraction of 24. Pure gold is thus 24K. Gold used in jewellery ranges from 9K to 22K. Pure gold tends not to be used very much in jewellery because it is too soft. Asians tend to prefer the higher Karat golds because they seem to value the intrinsic value of it more whereas 9K gold, which is relatively unpopular in Asian countries, is commonly found in jewellery in Western countries.
Gold medals are used to denote the winner in sports events such as the Olympics. A gold credit card shows a certain level of spending.
It has been estimated that ALL the gold ever mined throughout human history up to today only amounts to about 150,000 tons. Did you know all this would, if melted together, only make one solid cube about 30m on each side? Yes, it is that rare.
Once regarded as money, gold has been relegated to the level of a "barbarous relic" and the price of gold has been in a downward bear market for about 20 years since the spike to US$800/ounce in 1980 until the action got interesting recently...
Goldbugs can catch in on the commentary everyday at the Gold Discussion Forum at kitco.com at http://www.kitcomm.com/cgi-bin/comments/gold/display_short.cgi
Some figures:
Symbol - Au
Atomic Number - 79
Atomic Weight - 196.96655
Melting Point - 1064.43°C (1337.5801 K, 1947.9741°F)
Boiling Point - 2807.0°C (3080.15 K, 5084.6°F)
Specific Gravity - 19.32