From Wikipedia:

DIRT is unclean matter, especially when in contact with a person’s clothes, skin or possessions when they are said to become dirty. Common types of dirt include:

• dust — a general powder of organic or mineral matter
• filth — foul matter such as excrement
• grime — a black, ingrained dust such as soot
• soil — the mix of clay, sand, and humus which lies on top of bedrock