Gold

Gold is a chemical element with the symbol Au (from Latin: aurum) and atomic number 79. In its pure form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions.

Formation & Geology

Gold is found in ores in rocks often formed from Precambrian time onward. It most often occurs as a native metal, typically in a metal solid solution with silver (as electrum). It is found as nuggets or grains in rocks, in veins, and in alluvial deposits. Ore deposits of gold are formed via a very wide variety of geological processes. Deposits are classified as primary, alluvial or placer deposits, or residual or laterite deposits.

Physical Characteristics

Gold is the most malleable of all metals; a single gram can be beaten into a sheet of 1 square meter, and an ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent. It is a good conductor of heat and electricity. Gold has a specific gravity of 19.3, meaning it is much heavier than lead.

Historical Significance

Gold has been a highly sought-after precious metal for coinage, jewelry, and other arts since the beginning of recorded history. In the past, a gold standard was often implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was finally abandoned for a fiat currency system after 1971. A total of 197,576 tonnes of gold exists above ground, as of 2019.

Purity & Karat System

Gold purity is measured in karats (k). 24k gold is 99.9% pure but is too soft for most jewelry. 18k gold (75% gold) and 14k gold (58.3% gold) are alloyed with metals like copper, silver, or zinc to increase durability and alter color (creating rose or white gold). Bullion coins are typically 22k or 24k.