Gold (Au) is a dense, malleable, and ductile metal with an atomic number of 79. It has a Mohs hardness of 2.5-3, making it relatively soft but highly resistant to corrosion and tarnish. Found in both nugget and mineral form, gold commonly occurs in quartz veins, alluvial deposits, and as a byproduct of copper and silver mining. Major sources include China, Australia, Russia, the United States, and South Africa. Due to its rarity, conductivity, and resistance to oxidation, gold is widely used in jewelry, electronics, and as a financial reserve. It is often alloyed with other metals to enhance durability in commercial applications.