Gold

 

Gold is a chemical element with the symbol Au and atomic number 79. It is a dense, soft, malleable, and ductile metal with a bright yellow color and luster that is considered attractive, which is maintained without tarnishing in air or water. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements, solid under standard conditions. The metal therefore occurs often in free elemental (native) form, as nuggets or grains in rocks, inveins and in alluvial deposits. Less commonly, it occurs in minerals as gold compounds, usually with tellurium.

 

Gold resists attacks by individual acids, but it can be dissolved by the aqua regia (nitro-hydrochloric acid), so named because it dissolves gold. Gold also dissolves in alkaline solutions of cyanide, which have been used in mining. It dissolves in mercury, forming amalgam alloys; is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to confirm the presence of gold in items, giving rise to the term acid test.

 

This metal has been a valuable and highly sought-after precious metal for coinage, jewelry, and other arts since long before the beginning of recorded historyGold standards have sometimes been monetary policies, but were widely supplanted by fiat currency starting in the 1930s. The last gold certificate and gold coincurrencies were issued in the U.S. in 1932. In Europe, most countries left the gold standard with the start of World War I in 1914 and, with huge war debts, did not return to gold as a medium of exchange.

 

A total of 171,300 tonnes of gold have been mined in human history, according to GFMS as of 2011. This is roughly equivalent to 5.5 billion troy ounces or, in terms of volume, about 8876 m3, or a cube 20.7 m on a side. The world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry.

 

 

For further information, please click on the link below:

http://en.wikipedia.org/wiki/Gold

 

 

 



Source :

 

Wikipedia, The Free Encyclopedia

 


 

 

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