Crystalline Solids – the substances whose constituents are arranged in definite orderly arrangements. They possess characteristic geometric shapes and have sharp melting points. If cut or hammered gently they show a clean fracture among a smooth surface.
Amorphous Solids – the substances whose constituents are not arranged in an orderly manner. They do not have sharp melting points and do not occur in characteristic geometric shapes. When cut or hammered they break in an irregular manner.
Polycrystalline Solids – crystalline solids consisted of very fine crystals
