In this article we will discuss how are crystals formed. The process of crystals formation and crystal growth is called "nucleation". In simple words, this is the proces in which the molecules of the particular element start combining with each other and create crystal or grow the size of crystal. There are two different types of nucleation process. To understand the process of crystal formation and growth, let us study these two types of crystal formation processess, in detail. The two types are "unassisted nucleation" and "assisted nucleation".

The size of crystal keeps on growing but it stops the further growth, when an equilibrium is created between the solute molecules in the solution and in the crystal inside. Now the maximum size of crystal is formed and will not grow any more in the solution.

This was the process of crystal formation and growth with the unassisted nucleation process. As the name indicates, this is the process of crystals formation which is initiated by the molecules themselves without the assistance of some other solid material in the solution. In every solution there are two basic things solvent and solute. For example when sugar is mixed in the water, the water is called solvent(major part) and sugar is called solute (minor part).  Usually the solute molecules attract each other, but this attraction force is very weak and cannot result in the crystals formation. But in case, if the solute molecules are in the pure form, there may be some stronger forces of attraction among them. In this case the solute molecules start aggregating and grow in size.

The Assisted nucleation process of crystals formation and growth is very similar to unassisted method. The only difference is that another solid substance is added in the solution to start the process of molecules aggregation. When the solute molecules have not enough strong attraction between them then this process is used to make the crystals. Let me explain in a little detail the crystal formation with the process of assisted nucleation.

In this process, a solid thing like a brick or stone or some other thing is added in the solution. When this solid thing is added in the solution, the solute molecules are adsorbed in its surface for a longer time. During this time more and more solute molecules are adsorbed on the surface and gives the solute molecules a chance and place to combine with each other. The reason is that the solid stone resists the forces that try to separate the solute molecules in the solution. When a sufficient number of solute molecules are adsorbed on the surface, a protocrystal is formed. Now the rest of the process is same as was in the unassisted nucleation.