Silt is a term used to describe fine particles that, when rubbed between the fingers, have a slippery feel. Silt grains are between sand and clay in size. Silt grains are easily carried (and when they dry out are small enough to be carried by the wind).

Silt is common only in some parts of the world. It is often found in rivers that flow over dry landscapes. This picture of the Rio Grande in Texas shows a silty bed exposed because the river is low.

Silt is hard to distinguish from mud except by feel. Whereas mud is sticky and clings together, silt is slippery and feels like soap.

Silt is also a word used commonly instead of alluvium. However this is not an accurate use of the word. Silt makes up nearly two thirds of the sediment carried by the Mississippi.