Zeolites are microporous crystalline solids that possess a primary structure composed of MOn polyhedra, where M is usually silicon or aluminum. The most frequently encountered polyhedra in zeolites are tetrahedra (n=4) and they are arranged such that each oxygen atom on one tetrahedron is attached to the central atom of another. The tetrahedra combine in an ordered fashion to form polygonal or polyhedral units, which in turn combine to form the framework structure of zeolites. The progression from a single tetrahedron all the way to the framework structure of the faujasite class of zeolites is shown below...