Copper sulphate, also known as cupric sulphate, has the chemical formula CuSO4. It is a blue-green crystalline powder that is highly soluble in water. When dissolved in water, copper sulphate dissociates into copper ions (Cu2+) and sulphate ions (SO42-). These ions are then attracted to each other and form crystals.

The process of crystal formation is known as crystallisation. It is a process in which a solid forms from a liquid or gas. In the case of copper sulphate, the solid that forms is a crystal. Crystals are solids with a regular and repeating arrangement of atoms, molecules, or ions.

The shape of a crystal is determined by the arrangement of the atoms, molecules, or ions within the crystal. In the case of copper sulphate, the crystals are octahedral, which means that they have eight sides.

The colour of a crystal is determined by the presence of impurities. In the case of copper sulphate, the crystals are blue-green due to the presence of copper ions.

Copper sulphate crystals are used in a variety of applications, including:

* As a fungicide to prevent the growth of fungi

* As a mordant in dyeing to help dyes adhere to fabrics

* As a catalyst in chemical reactions

* As a source of copper in animal feed and fertiliser