Crystalline vs. Amorphous

Crystalline solids exhibit translational symmetry (periodicity of atomic positions, unit cell), while in
amorphous (glassy, or non-crystalline solids) lack the long-range order, but a short-range order still exists.

Types of disordered solid materials

Amorphous solids

Certain thin films: semiconductors, metals...

Glasses (supercooled liquids): Vitrious silica, oxide glasses, chalcogenide glasses

Composites: random alloys, metal-insulator mixtures, porous materials

Amorphous solids at intermediate length scales often exhibit fractal structure                                                         source: G. A. Niklasson