Crystal structure ( crystalline,polycrystalline and amorphous)

1.Solid material

a.Crystalline - crystalline is a solid material whose constituent atoms, molecules, or ions that  arranged in an orderly repeating pattern .Example,Quartz. The process of forming a crystalline structure from a fluid is a  crystallization / solidification process. 

 Figure 1

 Figure 2

    b.Polycrystalline - Polycrystalline materials are solids that are composed of many crystallites / grains of varying size and orientation

   c.Amorphous – Example of amorphous is glass,opal.It is considered as non-crystalline solid material.Atoms are not orderly repeating pattern.

  

Figure 3

 

Figure 4

Opal is an amorphous,refer figure 5

Opal (figure 5)

Observe the structure f this material,and compare to that of crytalline :

Figure 6

(Left is a crystall structure of quartz (crystalline),right the crystal structure of opal (amorphous)

Note : The difference between quartz ( crystalline solid) and glass (non crystalline solid) : the quartz have an orderly crystalline network,while the glass do not.