Silt Block

Silt Blocks were added in 1.1, and fall under the soils category. Like Sand Blocks, Silt Blocks are subject to gravity and will deal damage to any player or mob they fall on. Silt Blocks look similar to Ash Blocks, but are a lighter color.

Location
Below cavern level, mostly around the point where lava pools are spotted.

Uses
Silt can be used in the same way as sand, and can be used to fill lava pits. It can also be used in creating traps, since it causes damage to whatever it falls onto.