Cleavage is the tendency of a mineral to break along specific planes of weakness within its crystal structure. Copper sulfate crystals, while having a distinct crystal structure, do not possess the inherent structural weaknesses that lead to pronounced cleavage.

Here's why:

* Hydrated Structure: Copper sulfate crystals are hydrated, meaning they incorporate water molecules within their structure. This creates a more complex and less tightly bonded structure than many other minerals.

* Ionic Bonding: Copper sulfate crystals are held together primarily by ionic bonds, which are weaker than covalent bonds. This also contributes to a less defined cleavage pattern.

* Fracture: Instead of cleaving, copper sulfate crystals tend to fracture irregularly, showing conchoidal or uneven surfaces.

Therefore, while copper sulfate crystals have a distinct shape and crystal structure, they do not show well-defined cleavage planes.