But because the van der Waals bonding is weak, graphene layers can be easily pulled back apart.

This occurs when tape is peeled off a piece of graphite (which was how graphene was first discovered!).

Graphite layers also separate easily when force is applied, making graphite a good lubricant.

Finally, because each graphene layer within a graphite stack retains its flickering "resonant" and "conjugated" bonding, graphite is an electrical conductor