Gold Ore

Gold Ore is an early game ore which spawns in the Underground and Cavern layers. Its primary use is to make Gold Bars, which can be used to make the Gold tier of equipment, as well as crowns, Thrones, and several other items. The equivalent of Gold Ore is Platinum Ore, which will sometimes replace Gold in a world. Gold Ore has a small chance to appear as a bonus drop from slimes.

Trivia

 * In real life, gold is one of the softest metals, but in Terraria (as lampshaded by the Goblin Tinkerer) it is harder than such heavy-duty metals as iron or steel.
 * Even though Gold and Platinum Ore (and Bars) are of nearly equal sell value, 1 Platinum Coin is worth 100 Gold Coins. This is likely because Platinum Ore and Bars were added after Platinum Coins, and also is a reflection to the real-world metals (in this case, platinum would be the higher rank).