When I was a graduate student, interstellar dust was thought to be largely icy; what one now thinks of as cometary material.
But in fact, we found out in the meantime that dust is not that at all.
It is more like rocks, silicates and small pieces of carbon, which you might characterize as soot.
The other things that we discovered are that there is a wide range of particles sizes: they are not all one tenth of a micron in size.
Some are as small as molecules; in fact, there is a borderline area in which you can think of them as very tiny dust grains or as very large molecules.
Some of those large molecules are like small sheets of graphite with hydrogen attached to them: we call these polycyclic aromatic hydrocarbons and they can be found in terrestrial counterparts like mothballs, for example.
Automobile soot is another good representation of a mix of these compounds.