The particle size of silt soil is

Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. It is a common material, making up to 45% of average modern mud, found in many river deltas and as wind-deposited accumulations.
Silt is made up of rock and mineral particles that are larger than clay but smaller than sand. It ranges from 0.002 to 0.05 mm in diameter.