au

Au is the chemical element with the symbol Au and atomic number 79. It is a soft, dense, yellow metal classified as a transition metal in group 11. Gold is highly ductile and malleable, has excellent electrical and thermal conductivity, and resists corrosion and most acids, which helps explain its long-standing use in jewelry and investment.

Physically, gold is bright yellow with a distinctive luster. It is extremely ductile and malleable, can be hammered into thin sheets or drawn into fine wires. Its density is about 19.3 g/cm³, and it melts at 1,064 °C and boils at 2,856 °C. Gold alloys with silver or copper to form karat gold of varying hardness and color. The metal’s chemical inertness makes it suitable for use in electronics and protective coatings.

Gold occurs mainly as native metal in alluvial deposits and in quartz veins, often together with tellurides and sulfides. It is mined in many countries, with major producers including China, Australia, Russia, the United States, Peru, and South Africa. Production typically involves ore processing followed by cyanidation to extract gold, after which refining methods such as the Miller process or Wohlwill electrorefining yield higher-purity metal.

In commerce and technology, gold has served as a store of value and a monetary standard, and remains a key material in jewelry. It is essential in electronics due to its conductivity and resistance to corrosion, and it is used in dentistry, certain medical treatments, and in aerospace coatings. The only stable isotope is 197Au; numerous radioisotopes have been produced for research. While gold metal is relatively non-toxic, some gold compounds can be hazardous if misused. Its Latin name aurum underlies its chemical symbol.