A
granular material is a conglomeration of discrete
solid,
macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be
friction when grains collide). The constituents that compose granular material must be large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1
µm. On the upper size limit, the physics of granular materials may be applied to ice floes where the individual grains are
icebergs and to
asteroid belts of the
solar system with individual grains being
asteroids.