Au is the chemical symbol for gold, the precious metal used in jewelry and currency.
The symbol Au comes from the Latin word aurum, meaning “gold” or “gilded.” Gold’s atomic number is 79, placing it among the chemical elements. Its distinctive yellow color, resistance to corrosion, malleability, and relative scarcity have made it valuable across many societies.
Pure gold is very soft, so jewelry is commonly made from alloys measured in karats. Twenty-four-karat gold is treated as essentially pure, while 18-karat gold contains 75 percent gold and 25 percent other metals. The remaining metals can change the hardness and color of the finished material.
Gold has uses beyond decoration and money. Its excellent conductivity and resistance to oxidation make it useful in electronics, aerospace equipment, dentistry, and some medical applications. Gold is not the same as silver, whose symbol is Ag from argentum. The letters Au therefore cannot be inferred from the modern English word alone.