Gold

Gold is a chemical element with the symbol Au and atomic number 79. It is a dense, soft, yellow metal that is highly malleable and ductile, and it is corrosion resistant. Gold is one of the few elements that occurs in native form in the Earth's crust, often as nuggets or grains. A natural alloy with silver known as electrum also occurs. The most abundant native form is relatively pure but small amounts of other metals are commonly present.

Gold occurs in a variety of geological settings, including placer deposits formed by weathering and erosion, and hydrothermal veins. It is mined through placer mining, hard rock mining, and, increasingly, more specialized extraction methods. Refining removes impurities to produce high-purity gold, typically by smelting and chemical treatments, such as leaching with cyanide solutions followed by precipitation. Environmental and safety concerns accompany some refining processes, leading to ongoing development of alternative methods.

Uses for gold include jewelry, ornamentation, and investment in bullion and coins. It is valued for its aesthetic appeal, density, and resistance to corrosion. In electronics and dentistry, gold advantages include high electrical conductivity and biocompatibility, though its use is limited by cost. Gold also plays a role as a monetary asset; central banks hold gold reserves, and the global price is influenced by supply, demand, and macroeconomic factors.

The only stable isotope of gold is 197Au. Golden properties and cultural significance have made it a symbol of wealth and status across civilizations.