Iron Ore

Iron Ore is an early game ore, which spawns on the surface as well as in the Underground and Cavern biomes. Its primary use is to make Iron Bars, which can be used to make the Iron tier of equipment, as well as Buckets, Chains, and many other items. The equivalent of Iron Ore is Lead Ore, which will sometimes replace Iron in a world.

As Iron bars are needed to create an Iron Anvil, Iron Ore must usually be obtained before any weapons or armor can be created out of metal bars. This can be avoided by purchasing an Iron Anvil from the Merchant, but this is generally inefficient, as it is not difficult to find 15 Iron Ore early on in the game.

Trivia

 * Iron ore and lead ore are the only ores that don't have bricks.
 * Pure metallic iron is actually a lustrous silvery-gray color. However, iron is more often found in the form of iron–nickel alloys and iron oxide minerals (such as hematite, limonite and magnetite), which have a darker color. (see also Iron ore and Banded iron formations)
 * Real iron is also very malleable and generally not good for making tools with; the way iron is used in Terraria references real-world steel.

History
Minerai de Fer 철 광석 Iron Ore Железная руда