The best replacement for silt is clay.

The best alternatives to silt are rated as following:
★★★★★  clay
★★★  sand
★★★  loam
★★  clay smaller
★  sand bigger
  shale

Your alternative for silt is not listed? Suggest!
Speaking about silt, one probably shouldn't forget about sand.

Other search terms related to silt and their ratings are:
★★★★★ sand
You have in mind a companion for silt and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of silt in all years. Click on graph for more.
silt
clay
sand