Information taken from: webelements.com
Name: gold
Symbol: Au
Atomic number: 79
Atomic weight: 196.96655 (2)
CAS Registry ID: 7440-57-5
Group number: 11
Group name: Coinage metal
Period number: 6
Block: d-block
Standard state: solid at 298K
Color: gold
Classification: Metallic
Gold is usually alloyed in jewelry to give it more strength, and the term carat describes the amount of gold present (24 carats is pure gold). It is estimated that all the gold in the world, so far refined, could be placed in a single cube 60 ft. on a side. It is metallic, with a yellow color when in a mass, but when finely divided it may be black, ruby, or purple.
It is the most malleable and ductile metal; 1 ounce (28 g) of gold can be beaten out to 300 square feet. It is a soft metal and is usually alloyed to give it more strength. It is a good conductor of heat and electricity, and is unaffected by air and most reagents.
The most common gold compounds are auric chloride (AuCl3) and chlorauric acid (HAuCl4). A mixture of one part nitric acid with three of hydrochloric acid is called aqua regia (because it dissolved gold, the King of Metals). It is unaffected by air and most reagents. It is found free in nature and associated with quartz, pyrite and other minerals. Two thirds of the world's supply comes from South Africa, and 2/3 of USA production is from South Dakota and Nevada. Gold is found in sea water, but no effective economic process has been designed (yet) to extract it from this source.