To understand what good behavior is, it is useful to look at the reason for producing particles. Particles are usually produced by milling but may also be produced by other processes such as crystallization, precipitation, homogenization or fuming onto collector plates. Powdered materials fill a void better than boulders of material Powdered materials dissolve better or react faster owing to greater exposure of the surface to a reagent or solvent. Powdered materials are more economical in use than other forms. Powdering materials allows them to be mixed without reacting until water is added or they are ignited.
Powdered materials give the right bio-availability.
However, size reduction alone is not the only important parameter determining the effective performance of a particulate material. The first problem when someone wants to measure the size of a particle is one of interpretation. If, for a moment you consider yourself as a particle . It could be your waist, your inside leg measurement or a number of other things. The problem is that we are seeking a single descriptive value not the sum of a lot of individual dimensions.