Dust

Dust consists of particles in the atmosphere that come from various sources such as soil dust lifted by weather (an Aeolian process), volcanic eruptions, and pollution. Dust in homes, offices, and other human environments contains small amounts of plant pollen, human and animal hairs, textile fibers, paper fibers, minerals from outdoor soil, human skin cells, burnt meteorite particles and many other materials which may be found in the local environment.

The Justice League spectral analyzer detected dust on a piece of paper that Batman was analyzing. The type of dust was volcanic ash.