a crystal is made due to hexagonal arrangement of molecules
They are made up of a lattice structure of positive and negative ions.
It depends on what the crystals are being made from. Ice is a crystal made up of water (hydrogen and oxygen) Quartz is a crystal made up of silica and oxygen Pyrite (fools gold) is a crystal made...
Crystals are made when positive and negative ions come together to form a lattice structure.