Dirt Block

Dirt Blocks are one of the most common block types in Terraria, covering the majority of the world's surface.

Dirt Blocks may be covered by regular grass, Corrupt grass, Crimson grass, or Hallowed grass, which spreads from nearby grass-covered Dirt Blocks. It can also be turned into regular grass by using the Staff of Regrowth.

In all cases, the grass applies to the block as a whole, and will appear on all exposed surfaces. If a grass block is covered by blocks on its four sides, the grass will remain and show as markings on the block. However, if the block is completely surrounded with eight blocks, the grass is lost and the block will revert to regular dirt.

Dirt blocks emit little dusty particles when walked or landed on. Dirt occurs naturally almost everywhere throughout the world. All caves above the elevation of 0 ft are made of dirt. Below 0 ft, in the underground layer, the caves are made of roughly 50% dirt. Small patches of dirt can be found in the cavern layer, though it is mostly made of stone.

Notes

Dirt Blocks are one of the most fragile blocks in the game. A single hit from most pickaxes will successfully mine them, but Dirt Blocks with any kind of grass on them will take an additional hit. In Hardmode, the evil biomes are capable of converting nearby Mud Blocks to Dirt Blocks, and Chlorophyte Ore is capable of doing the reverse. Dirt Blocks can be moved around freely with a Dirt Rod.

Trivia

In some of his quotes, the Merchant claims to sell dirt, despite not actually selling it.